BBA - Molecular Basis of Disease (v.1862, #4)
Editorial Board (i).
Lipoic acid improves neuronal insulin signalling and rescues cognitive function regulating VGlut1 expression in high-fat-fed rats: Implications for Alzheimer's disease by Manuel Rodriguez-Perdigon; Maite Solas; Maria Jesús Moreno-Aliaga; Maria Javier Ramirez (511-517).
The concept of central insulin resistance and dysfunctional insulin signalling in sporadic Alzheimer's disease (AD) is now widely accepted and diabetes is recognized as one of the main risk factors for developing AD. Moreover, some lines of evidence indicated that VGlut1 is impaired in frontal regions of AD patients and this impairment is correlated with the progression of cognitive decline in AD. The present work hypothesizes that ketosis associated to insulin resistance could interfere with the normal activity of VGlut1 and its role in the release of glutamate in the hippocampus, which might ultimately lead to cognitive deficits. High fat diet (HFD) rats showed memory impairments and both peripheral (as shown by increased fasting plasma insulin levels and HOMA index) and hippocampal (as shown by decreased activation of insulin receptor, IRS-1 and pAkt) insulin pathway alterations, accompanied by increased ketone bodies production. All these effects were counteracted by α-lipoic acid (LA) administration. VGlut1 levels were significantly decreased in the hippocampus of HFD rats, and this decrease was reversed by LA. Altogether, the present results suggest that HFD induced alterations in central insulin signalling could switch metabolism to produce ketone bodies, which in turn, in the hippocampus, might lead to a decreased expression of VGlut1, and therefore to a decreased release of glutamate and hence, to the glutamatergic deficit described in AD. The ability of LA treatment to prevent the alterations in insulin signalling in this model of HFD might represent a possible new therapeutic target for the treatment of AD.
Keywords: High-fat-diet; Insulin; Ketone bodies; Cognitive deficits; VGlut1;
Differential interaction between iron and mutant alpha-synuclein causes distinctive Parkinsonian phenotypes in Drosophila by Zhou-Jing Zhu; Ka-Chun Wu; Wing-Ho Yung; Zhong-Ming Qian; Ya Ke (518-525).
Alpha-synuclein aggregation is the central hallmark of both sporadic and familial Parkinson's disease (PD). Patients with different PD-causing genetic defects of alpha-synuclein usually show distinctive clinical features that are atypical to sporadic PD. Iron accumulation is invariably found in PD. Recent studies showed that mutant and wild-type alpha-synuclein may have differential interaction with iron and mutant alpha-synuclein toxicity could be preferentially exacerbated by iron. We hence hypothesized that iron overload could selectively influence mutant alpha-synuclein toxicity and disease phenotypes. To test the hypothesis, we investigated if Drosophila melanogaster over-expressing A53T, A30P, and wild-type (WT) alpha-synuclein have different responses to iron treatment. We showed that iron treatment induced similar reduction of survival rate in all flies but induced a more severe motor decline in A53T and A30P mutant alpha-synuclein expressing flies, suggesting interaction between mutant alpha-synuclein and iron. Although no significant difference in total head iron content was found among these flies, we demonstrated that iron treatment induced selective DA neuron loss in motor-related PPM3 cluster only in the flies that express A53T and A30P mutant alpha-synuclein.We provided the first in vivo evidence that iron overload could induce distinctive neuropathology and disease phenotypes in mutant but not WT alpha-synuclein expressing flies, providing insights to the cause of clinical features selectively exhibited by mutant alpha-synuclein carriers.
Keywords: Parkinson's disease; Drosophila melanogaster; Iron; Alpha-synuclein; A53T and A30P; Dopaminergic neuron;
Oral intake of genetically engineered high-carotenoid corn ameliorates hepatomegaly and hepatic steatosis in PTEN haploinsufficient mice by Nuria Eritja; Gemma Arjó; Maria Santacana; Sònia Gatius; Omar Ramírez-Núñez; Laura Arcal; José C.E. Serrano; Reinald Pamplona; Xavi Dolcet; Carme Piñol; Paul Christou; Xavier Matias-Guiu; Manuel Portero-Otin (526-535).
Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease. Here we show that a mouse model of haploinsufficiency in the lipid and protein phosphatase and tensin homolog protein (PTEN+/−) exhibits hepatomegaly, increased liver lipogenic gene expression (SREBP-1C and PPARγ) and hepatic lesions analogous to human NAFLD. The livers of PTEN+/− mice also contained lower levels of retinoic acid (RA) than normal, similarly to human NAFLD patients. The RA signaling pathway thus offers a novel therapeutic target for the treatment of NAFLD although the impact of nutrition in this context is unclear. We therefore fed PTEN+/− mice for 36 weeks a diet containing genetically engineered high-carotenoid corn (HCAR) to investigate its potential beneficial effects on the hepatic symptoms of NAFLD. The HCAR diet reduced hepatomegaly and promoted the repartitioning of fatty acids in the liver, away from triacylglycerol storage. At the molecular level, the HCAR diet clearly reduced lipogenic gene expression, boosted catabolism, and increased hepatic RA levels. These results set the stage for human trials to evaluate the use of high-carotenoid foods for the reduction or prevention of steatosis in NAFLD.
Keywords: Non-alcoholic fatty liver disease (NAFLD); Genetically engineered high-carotenoid corn; PTEN; Retinoic acid;
Tetrahydrobiopterin Role in human umbilical vein endothelial dysfunction in maternal supraphysiological hypercholesterolemia by Andrea Leiva; Bárbara Fuenzalida; Rocío Salsoso; Eric Barros; Fernando Toledo; Jaime Gutiérrez; Fabián Pardo; Luis Sobrevia (536-544).
Maternal physiological hypercholesterolemia (MPH) allows a proper foetal development; however, maternal supraphysiological hypercholesterolemia (MSPH) associates with foetal endothelial dysfunction and early development of atherosclerosis. MSPH courses with reduced endothelium-dependent dilation of the human umbilical vein due to reduced endothelial nitric oxide synthase activity compared with MPH. Whether MSPH modifies the availability of the nitric oxide synthase cofactor tetrahydrobiopterin is unknown. We investigated whether MSPH-associated lower umbilical vein vascular reactivity results from reduced bioavailability of tetrahydrobiopterin. Total cholesterol < 7.2 mmol/L was considered as maternal physiological hypercholesterolemia (n = 72 women) and ≥ 7.2 mmol/L as MSPH (n = 35 women). Umbilical veins rings were used for vascular reactivity assays (wire myography), and primary cultures of human umbilical vein endothelial cells (HUVECs) to measure nitric oxide synthase, GTP cyclohydrolase 1, and dihydrofolate reductase expression and activity, as well as tetrahydrobiopterin content. MSPH reduced the umbilical vein rings relaxation caused by calcitonine gene-related peptide, a phenomenon partially improved by incubation with sepiapterin. HUVECs from MSPH showed lower nitric oxide synthase activity (l-citrulline synthesis from l-arginine) without changes in its protein abundance, as well as reduced tetrahydrobiopterin level compared with MPH, a phenomenon reversed by incubation with sepiapterin. Expression and activity of GTP cyclohydrolase 1 was lower in MSPH, without changes in dihydrofolate reductase expression. MSPH is a pathophysiological condition reducing human umbilical vein reactivity due to lower bioavailability of tetrahydrobiopterin leading to lower NOS activity in the human umbilical vein endothelium.
Keywords: Tetrahydrobiopterin; Foetal; Endothelium; Cholesterol; Pregnancy;
Interplay between exercise and dietary fat modulates myelinogenesis in the central nervous system by Hyesook Yoon; Andrew Kleven; Alex Paulsen; Laurel Kleppe; Jianmin Wu; Zhe Ying; Fernando Gomez-Pinilla; Isobel A. Scarisbrick (545-555).
Here we show that the interplay between exercise training and dietary fat regulates myelinogenesis in the adult central nervous system. Mice consuming high fat with coordinate voluntary running wheel exercise for 7 weeks showed increases in the abundance of the major myelin membrane proteins, proteolipid (PLP) and myelin basic protein (MBP), in the lumbosacral spinal cord. Expression of MBP and PLP RNA, as well that for Myrf1, a transcription factor driving oligodendrocyte differentiation were also differentially increased under each condition. Furthermore, expression of IGF-1 and its receptor IGF-1R, known to promote myelinogenesis, were also increased in the spinal cord in response to high dietary fat or exercise training. Parallel increases in AKT signaling, a pro-myelination signaling intermediate activated by IGF-1, were also observed in the spinal cord of mice consuming high fat alone or in combination with exercise. Despite the pro-myelinogenic effects of high dietary fat in the context of exercise, high fat consumption in the setting of a sedentary lifestyle reduced OPCs and mature oligodendroglia. Whereas 7 weeks of exercise training alone did not alter OPC or oligodendrocyte numbers, it did reverse reductions seen with high fat. Evidence is presented suggesting that the interplay between exercise and high dietary fat increase SIRT1, PGC-1α and antioxidant enzymes which may permit oligodendroglia to take advantage of diet and exercise-related increases in mitochondrial activity to yield increases in myelination despite higher levels of reactive oxygen species.Display Omitted
Keywords: Exercise; Dietary fat; Western diet; Spinal cord; Myelin; Oligodendrocyte;
CYB5D2 displays tumor suppression activities towards cervical cancer by Yanyun Xie; Yen Ting Shen; Anil Kapoor; Diane Ojo; Fengxiang Wei; Jason De Melo; Xiaozeng Lin; Nicholas Wong; Judy Yan; Lijian Tao; Pierre Major; Damu Tang (556-565).
Cervical cancer is caused by infections with human papillomaviruses (HPV) and genetic alternations in the cervical epithelium. While the former is well studied, the latter remains unclear. We report here that CYB5D2/Neuferricin possesses tumor suppressing activity towards cervical tumorigenesis. Ectopic expression of CYB5D2 did not affect HeLa cell proliferation and the cell's ability to form xenograft tumors, but significantly inhibited HeLa cell invasion in vitro and the cell-produced lung metastasis in NOD/SCID mice. Knockdown of CYB5D2 enhanced HeLa cell invasion. Two mutations in CYB5D2, the substitutions of arginine (R) 7 with either proline (P) or glycine (G), were reported in colon cancer. Both CYB5D2(R7P) and CYB5D2(R7G) were incapable of inhibiting HeLa cell invasion. CYB5D2 binds heme, in which aspartate (D) 86 is required. While CYB5D2(D86G) is heme-binding defective, it inhibited HeLa cell invasion. On the other hand, CYB5D2(R7P) and CYB5D2(R7G) bound heme but did not inhibit HeLa cell invasion. Collectively, CYB5D2 inhibits HeLa cell invasion independently of its heme binding. Furthermore, immunohistochemistry examination of CYB5D2 expression in 20 normal cervical tissues and 40 cervical squamous cell carcinomas (SCC) revealed a CYB5D2 reduction in 87.5% (35/40) of SCC. Analysis of CYB5D2 gene expression and genomic alteration data available from Oncomeine™ detected significant reductions of CYB5D2 mRNA in 40 SCCs and CYB5D2 gene copy number in 107 SCCs. Collectively, we provide evidence that CYB5D2 is a candidate tumor suppressor of cervical tumorigenesis.
Keywords: CYB5D2; Tumor suppressor; Cervical cancer; Xenograft tumors; Metastasis;
Baicalein reverts L-valine-induced persistent sodium current up-modulation in primary cortical neurons by Silvia Caioli; Elena Candelotti; Jens Z. Pedersen; Luana Saba; Alessia Antonini; Sandra Incerpi; Cristina Zona (566-575).
L-valine is a branched-chain amino acid (BCAA) largely used as dietary integrator by athletes and involved in some inherited rare diseases such as maple syrup urine disease. This pathology is caused by an altered BCAA metabolism with the accumulation of toxic keto acids in tissues and body fluids with consequent severe neurological symptoms. In animal models of BCAA accumulation, increased oxidative stress levels and lipid peroxidation have been reported. The aim of this study was to analyze both whether high BCAA concentrations in neurons induce reactive oxygen species (ROS) production and whether, by performing electrophysiological recordings, the neuronal functional properties are modified. Our results demonstrate that in primary cortical cultures, a high dose of valine increases ROS production and provokes neuronal hyperexcitability because the action potential frequencies and the persistent sodium current amplitudes increase significantly compared to non-treated neurons. Since Baicalein, a flavone obtained from the Scutellaria root, has been shown to act as a strong antioxidant with neuroprotective effects, we evaluated its possible antioxidant activity in primary cortical neurons chronically exposed to L-valine. The preincubation of cortical neurons with Baicalein prevents the ROS production and is able to revert both the neuronal hyperexcitability and the increase of the persistent sodium current, indicating a direct correlation between the ROS production and the altered physiological parameters. In conclusion, our data show that the electrophysiological alterations of cortical neurons elicited by high valine concentration are due to the increase in ROS production, suggesting much caution in the intake of BCAA dietary integrators.
Keywords: Branched-chain amino acids; Reactive oxygen species; Antioxidant; Neuronal hyperexcitability; Persistent sodium current; Baicalein;
ROS/oxidative stress signaling in osteoarthritis by Panagiotis Lepetsos; Athanasios G. Papavassiliou (576-591).
Osteoarthritis is the most common joint disorder with increasing prevalence due to aging of the population. Its multi-factorial etiology includes oxidative stress and the overproduction of reactive oxygen species, which regulate intracellular signaling processes, chondrocyte senescence and apoptosis, extracellular matrix synthesis and degradation along with synovial inflammation and dysfunction of the subchondral bone. As disease-modifying drugs for osteoarthritis are rare, targeting the complex oxidative stress signaling pathways would offer a valuable perspective for exploration of potential therapeutic strategies in the treatment of this devastating disease.
Keywords: Osteoarthritis; Oxidative stress; Chondrocytes; Reactive oxygen species; NO; Cartilage;
Mitochondrial response to the BCKDK-deficiency: Some clues to understand the positive dietary response in this form of autism by A. Oyarzabal; I. Bravo-Alonso; M. Sánchez-Aragó; M.T. Rejas; B. Merinero; A. García-Cazorla; R. Artuch; M. Ugarte; P. Rodríguez-Pombo (592-600).
Mutations on the mitochondrial-expressed Branched Chain α-Keto acid Dehydrogenase Kinase (BCKDK) gene have been recently associated with a novel dietary-treatable form of autism. But, being a mitochondrial metabolism disease, little is known about the impact on mitochondrial performance. Here, we analyze the mitochondrial response to the BCKDK-deficiency in patient's primary fibroblasts by measuring bioenergetics, ultra-structural and dynamic parameters. A two-fold increase in superoxide anion production, together with a reduction in ATP-linked respiration and intracellular ATP levels (down to 60%) detected in mutants fibroblasts point to a general bioenergetics depletion that could affect the mitochondrial dynamics and cell fate. Ultrastructure analysis of BCKDK-deficient fibroblasts shows an increased number of elongated mitochondria, apparently associated with changes in the mediator of inner mitochondria membrane fusion, GTPase OPA1 forms, and in the outer mitochondrial membrane, mitofusin 2/MFN2. Our data support a possible hyperfusion response of BCKDK-deficient mitochondria to stress. Cellular fate also seems to be affected as these fibroblasts show an altered proportion of the cells on G0/G1 and G2/M phases. Knockdown of BCKDK gene in control fibroblasts recapitulates most of these features. Same BCKDK-knockdown in a MSUD patient fibroblasts unmasks the direct involvement of the accelerated BCAAs catabolism in the mitochondrial dysfunction. All these data give us a clue to understand the positive dietary response to an overload of branched-chain amino acids. We hypothesize that a combination of the current therapeutic option with a protocol that considers the oxidative damage and energy expenditure, addressing the patients' individuality, might be useful for the physicians.
Keywords: BCKDK-deficiency; Bioenergetics profile; Autism; Mitochondrial disease; Mitochondrial elongation; Unrestrained branched-chain amino acids catabolism;
Altered S-nitrosothiol homeostasis provides a survival advantage to breast cancer cells in HER2 tumors and reduces their sensitivity to trastuzumab by Amanda Cañas; Laura M. López-Sánchez; Jon Peñarando; Araceli Valverde; Francisco Conde; Vanessa Hernández; Elena Fuentes; Chary López-Pedrera; Juan R. de la Haba-Rodríguez; Enrique Aranda; Antonio Rodríguez-Ariza (601-610).
The monoclonal antibody trastuzumab against HER2/neu, which is overexpressed in 15–20% of breast cancers, has clinical efficacy but many patients do not respond to initial treatment or develop resistance during treatment. Nitric oxide (NO) regulates cell signaling by targeting specific cysteine residues in proteins, forming S-nitrosothiols (SNO) in a process known as S-nitrosylation. We previously reported that molecular characteristics in breast cancer may dictate the tumor response to impaired SNO homeostasis. In the present study, we explored the role of SNO homeostasis in HER2 breast tumors.The antiproliferative action of trastuzumab in HER2-overexpressing BT-474 and SKBR-3 cells was suppressed when S-nitrosoglutathione reductase (GSNOR/ADH5) activity, which plays a key role in SNO homeostasis, was specifically inhibited with the pyrrole derivative compound N6022. Moreover, GSNOR inhibition restored the activation of survival signaling pathways involved in the resistance to anti-HER2 therapies (AKT, Src and c-Abl kinases and TrkA/NRTK1, TrkB/NRTK2, EphA1 and EphA3 receptors) and reduced the apoptotic effect of trastuzumab. Accordingly, GSNOR inhibition augmented the S-nitrosylation of apoptosis-related proteins, including Apaf-1, pSer73/63 c-Jun, calcineurin subunit α and HSF1. In agreement with in vitro data, immunohistochemical analyses of 51 breast tumors showed that HER2 expression was associated with lower expression of GSNOR protein. Moreover, gene expression analysis confirmed that high ADH5/GSNOR gene expression was associated with high patient survival rates in HER2 tumors.In conclusion, our data provide evidence of molecular mechanisms contributing to the progression of HER2 + breast cancers and could facilitate the development of therapeutic options to counteract resistance to anti-HER2 therapies.
Keywords: Apoptosis; Breast cancer; S-nitrosoglutathione reductase; HER2/neu; Nitric oxide; S-nitrosylation;
miR-322 regulates insulin signaling pathway and protects against metabolic syndrome-induced cardiac dysfunction in mice by Alexandre Marchand; Fabrice Atassi; Nathalie Mougenot; Michel Clergue; Veronica Codoni; Jeremy Berthuin; Carole Proust; David-Alexandre Trégouët; Jean-Sébastien Hulot; Anne-Marie Lompré (611-621).
We identified murine miR-322, orthologous to human miR-424, as a new regulator of insulin receptor, IGF-1 receptor and sirtuin 4 mRNA in vitro and in vivo in the heart and found that miR-322/424 is highly expressed in the heart of mice. C57Bl/6N mice fed 10 weeks of high fat diet (HFD) presented signs of cardiomyopathy and a stable miR-322 cardiac level while cardiac function was slightly affected in 11 week-old ob/ob which overexpressed miR-322. We thus hypothesized that mmu-miR-322 could be protective against cardiac consequences of hyperinsulinemia and hyperlipidemia. We overexpressed or knocked-down mmu-miR-322 using AAV9 and monitored cardiac function in wild-type C57Bl/6N mice fed a control diet (CD) or a HFD and in ob/ob mice. The fractional shortening progressively declined while the left ventricle systolic diameter increased in HFD mice infected with an AAVcontrol or with an AAVsponge (decreasing miR-322 bioavailability) but also in ob/ob mice infected with AAVsponge. Similar observations were also found in CD-fed mice infected with AAVsponge. On the contrary over-expressing miR-322 with AAVmiR-322 was efficient in protecting the heart from HFD effects in C57Bl/6N mice. This cardioprotection could be associated with the regulation of identified targets IGF1R, INSR and CD1, a decrease in insulin signaling pathway and an enrichment of genes involved in mitochondrial function and fatty acid oxidation as demonstrated by transcriptome analysis. Altogether, these results emphasize miR-322 as a new potential therapeutic target against cardiac consequences of metabolic syndrome, which represents an increasing burden in the western countries.Display Omitted
Keywords: MicroRNA; Cardiomyopathy; High fat diet; Insulin pathway; Metabolic syndrome;
Mitochondrial aldehyde dehydrogenase protects against doxorubicin cardiotoxicity through a transient receptor potential channel vanilloid 1-mediated mechanism by Wei Ge; Ming Yuan; Asli F. Ceylan; Xiaoming Wang; Jun Ren (622-634).
Cardiotoxicity is one of the major life-threatening effects encountered in cancer chemotherapy with doxorubicin and other anthracyclines. Mitochondrial aldehyde dehydrogenase (ALDH2) may alleviate doxorubicin toxicity although the mechanism remains elusive. This study was designed to evaluate the impact of ALDH2 overexpression on doxorubicin-induced myocardial damage with a focus on mitochondrial injury. Wild-type (WT) and transgenic mice overexpressing ALDH2 driven by chicken β-actin promoter were challenged with doxorubicin (15 mg/kg, single i.p. injection, for 6 days) and cardiac mechanical function was assessed using the echocardiographic and IonOptix systems. Western blot analysis was used to evaluate intracellular Ca2 + regulatory and mitochondrial proteins, PKA and its downstream signal eNOS. Doxorubicin challenge altered cardiac geometry and function evidenced by enlarged left ventricular end systolic and diastolic diameters, decreased factional shortening, cell shortening and intracellular Ca2 + rise, prolonged relengthening and intracellular Ca2 + decay, the effects of which were attenuated by ALDH2. Doxorubicin challenge compromised mitochondrial integrity and upregulated 4-HNE and UCP-2 levels while downregulating levels of TRPV1, SERCA2a and PGC-1α, the effects of which were alleviated by ALDH2. Doxorubicin-induced cardiac functional defect and apoptosis were reversed by the TRPV1 agonist SA13353 and the ALDH-2 agonist Alda-1 whereas the TRPV1 antagonist capsazepine nullified ALDH2/Alda-1-induced protection. Doxorubicin suppressed phosphorylation of PKA and eNOS, the effect of which was reversed by ALDH2. Moreover, 4-HNE mimicked doxorubicin-induced cardiomyocyte anomalies, the effect of which was ablated by SA13353. Taken together, our results suggested that ALDH2 may rescue against doxorubicin cardiac toxicity possibly through a TRPV1-mediated protection of mitochondrial integrity.
Keywords: Doxorubicin; ALDH2; Myocardial function; Mitochondrial; TRPV1;
NFκBiz protein downregulation in acute kidney injury: Modulation of inflammation and survival in tubular cells by Jonay Poveda; Ana B. Sanz; Sandra Rayego-Mateos; Marta Ruiz-Ortega; Susana Carrasco; Alberto Ortiz; Maria D. Sanchez-Niño (635-646).
Acute kidney injury is characterized by decreased renal function, tubular cell death and interstitial inflammation. The transcription factor NF-κB is a key regulator of genes involved in cell survival and the inflammatory response. In order to better understand the regulation and role of NF-κB in acute kidney injury we explored the expression of NF-κB-related genes in experimental acute kidney injury induced by a folic acid overdose. NFκBiz, a member of the IκB family of NF-κB regulators encoding NFκBiz, was among the top up-regulated NF-κB-related genes at the mRNA level in experimental acute kidney injury. However, the NFκBiz protein was constitutively expressed by normal tubular cells but was down-regulated in experimental acute kidney injury. Kidney NFκBiz mRNA upregulation and protein downregulation was also observed in acute kidney injury induced by cisplatin or unilateral kidney injury resulting from ureteral obstruction. Thus, we studied the consequences of NFκBiz protein downregulation by specific siRNA in cultured tubular epithelial cells. NFκBiz mRNA and protein were up-regulated by inflammatory cytokines (IL-1β or TWEAK/TNFα/IFNγ) and by LPS in cultured tubular cells. However, TWEAK only induced a very mild and short lived NFκBiz upregulation. NFκBiz targeting increased chemokine production and dampened Klotho downregulation induced by TWEAK, without modulating cell proliferation. NFκBiz targeting also rendered cells more resistant to apoptosis induced by serum deprivation or inflammatory cytokines. In conclusion, NFκBiz differentially regulates NF-κB-mediated responses of tubular cells to inflammatory cytokines in a gene-specific manner, and may be of potential therapeutic interest to limit inflammation in kidney disease.
Keywords: Acute kidney injury; Inflammation; Apoptosis; NF-κB; Transcription factor; TNF; Tweak;
Protective effect of vitamin E against alloxan-induced mouse hyperglycemia by Kazunori Takemoto; Wakana Doi; Noriyoshi Masuoka (647-650).
Alloxan induces oxidative stress and hyperglycemia in animal models. Acatalasemic (catalase deficiency) mice are susceptible to alloxan-induced hyperglycemia. As the incidence of hyperglycemia induced by alloxan was reportedly improved when mice were fed a vitamin E supplemented diet, this protective effect was examined.Acatalasemic and normal mice fed a vitamin E supplemented diet were treated with alloxan. The pancreas were examined with microscopy. We also isolated pancreatic islets of normal mice treated with alloxan. The glucose stimulated insulin secretion was examined.Vitamin E powerfully ameliorated the increase in apoptosis. Vitamin E increases insulin amounts secreted from pancreatic cells, but does not ameliorate the regulation of the glucose stimulated insulin secretion.It is suggested that the difference in the mice fed vitamin E supplemented diet is due to an increase of insulin secretion and that vitamin E supplementation may have a role in helping to slow the stages of diabetes mellitus.
Keywords: α-Tocopherol; Alloxan; Apoptosis; Insulin; Beta-cell; Hyperglycemia;
Serotonin as a putative scavenger of hypohalous acid in the brain by Mike Kalogiannis; E. James Delikatny; Thomas M. Jeitner (651-661).
Neurodegenerative disorders represent the culmination of numerous insults including oxidative stress. The long etiology of most of these disorders suggests that lessening the effects of one or more of the insults could significantly delay disease onset. Antioxidants have been tested as possible therapeutics for neurodegenerative disorders, but with little success. Here we report that serotonin acts as a scavenger of hypochlorous acid (HOCl) in the brain. Serotonin was shown to prevent the oxidation of 2-thio-5-nitrobenzoate by HOCl in a biphasic manner. The first phase was a partial scavenging that occurred at concentrations of serotonin that exceeded those of HOCl. 1H-NMR studies indicated that HOCl chlorinates both the aryl and akyl nitrogen atoms of serotonin. Thus, the oxidation of 2-thio-5-nitrobenzoate that occurred during the first phase of scavenging is likely due to the formation of serotonergic chloramines. A second phase of scavenging occurred at concentrations of HOCl that exceeded those of serotonin. Under these conditions, the chlorinated serotonin polymerized and formed inert aggregates. Serotonin was further shown to prevent the loss of cells and cellular α-ketoglutarate dehydrogenase complex activity caused by HOCl. Extracellular concentrations of serotonin in the brain can be elevated with selective serotonin reuptake inhibitors and suggests that such compounds could be used to increase the cerebral antioxidant capacity. Acute administration of selective serotonin reuptake inhibitors to mice treated with endotoxin partially mitigated sickness behavior and protein chlorination in the brain. These observations suggest that serotonin may act to suppress chlorinative stress in the brain.
Keywords: Serotonin; Brain; Neurodegenerative diseases; Hypochlorous acid; Antioxidant; Myeloperoxidase;
Enhanced hepatotoxicity by acetaminophen in Vanin-1 knockout mice is associated with deficient proliferative and immune responses by Daniel W. Ferreira; Michael J. Goedken; Samuel Rommelaere; Lionel Chasson; Franck Galland; Philippe Naquet; José E. Manautou (662-669).
Pretreatment with clofibrate, a peroxisome proliferator-activated receptor alpha (PPARa) agonist, protects mice from acetaminophen (APAP) injury. Protection is not due to alterations in APAP metabolism and is dependent on PPARa expression. Gene array analysis revealed that mice receiving clofibrate have enhanced hepatic Vanin-1 (Vnn1) gene expression, a response that is also PPARa dependent.We examined the role of Vnn1 by comparing the responses of Vnn1 knockout and wild-type mice following APAP hepatotoxicity. APAP metabolism, hepatotoxicity, and compensatory hepatocyte proliferation and immune responses were assessed.Vnn1 knockout mice are more susceptible to APAP hepatotoxicity despite no differences in hepatic glutathione content, gene expression of APAP metabolizing enzymes, or hepatic capacity to bioactivate or detoxify APAP ex vivo. Together, these data strongly suggest that the susceptibility of Vnn1 knockout mice is not due to differences in APAP metabolism. Immunochemistry revealed a lack of proliferating cell nuclear antigen-positive hepatocytes and F4/80-positive macrophages in and around areas of centrilobular necrosis in APAP-treated Vnn1 knockouts. Hepatic gene induction of pro-inflammatory cytokines was either significantly reduced or completely blunted in these mice. This was correlated with a reduction in early recruitment of cells positive for granulocyte differentiation antigen 1 or integrin alpha M. Heightened toxicity was also observed in CCl4 and ConA hepatitis models in the absence of Vnn1.These results indicate that mice lacking Vnn1 have deficiencies in compensatory repair and immune responses following toxic APAP exposure and that these mechanisms may contribute to the enhanced hepatotoxicity seen.
Keywords: Pantetheine hydrolase; Cysteamine; Clofibrate; Peroxisome proliferators; Liver;
EPAS1/HIF-2 alpha-mediated downregulation of tissue factor pathway inhibitor leads to a pro-thrombotic potential in endothelial cells by Benedicte Stavik; Sandra Espada; Xue Yan Cui; Nina Iversen; Sverre Holm; Marie-Christine Mowinkel; Bente Halvorsen; Grethe Skretting; Per Morten Sandset (670-678).
Neovascularization and hemorrhaging are evident in advanced atherosclerotic plaques due to hypoxic conditions, and mediate the accumulation of metabolic substrates, inflammatory cells, lipids, and other blood born factors inside the plaque. Tissue factor (TF) pathway inhibitor (TFPI) is mainly expressed by endothelial cells and is the endogenous inhibitor of the coagulation activator TF, which together with the downstream product thrombin can drive plaque progression and atherogenesis. We aimed to investigate the effect of hypoxic conditions on endothelial cell expression and activity of TFPI and TF that are important in coagulation initiation.Hypoxia was induced in primary human umbilical vein endothelial cells using chemicals or 1% oxygen tension, and mRNA and protein expressions were measured using qRT-PCR, ELISA, and Western blot analysis. Microscopy of fluorescence-labeled cells was used to visualize cell-associated TFPI. Cell-surface factor Xa (FXa) activity was measured using a two-stage chromogenic substrate method. We found that hypoxia reduced the TFPI mRNA and protein levels and increased the TF mRNA expression in a dose-dependent manner. The effect on TFPI was apparent on all the protein pools of TFPI, i.e., secreted TFPI, cell-surface associated TFPI, and intracellular TFPI, and seemed to be dependent upon hypoxia inducible factor-2α (HIF-2α). An increase in FXa activity was also observed on the endothelial cell surface, reflecting an increase in pro-thrombotic potential of the cells.Our findings indicate that hypoxic conditions may enhance the pro-coagulant activity of endothelial cells, which may promote atherogenesis in addition to clinical events and thus the severity of atherosclerotic disorders.
Keywords: Tissue factor pathway inhibitor; Hypoxia; HIF-2α; Atherosclerosis;
Metabolic, enzymatic and gene involvement in cerebral glucose dysmetabolism after traumatic brain injury by Angela Maria Amorini; Giacomo Lazzarino; Valentina Di Pietro; Stefano Signoretti; Giuseppe Lazzarino; Antonio Belli; Barbara Tavazzi (679-687).
In this study, the metabolic, enzymatic and gene changes causing cerebral glucose dysmetabolism following graded diffuse traumatic brain injury (TBI) were evaluated. TBI was induced in rats by dropping 450 g from 1 (mild TBI; mTBI) or 2 m height (severe TBI; sTBI). After 6, 12, 24, 48, and 120 h gene expressions and enzymatic activities of glycolysis and pentose phosphate pathway (PPP) enzymes, and levels of lactate, ATP, ADP, ATP/ADP (indexing mitochondrial phosphorylating capacity), NADP+, NADPH and GSH were determined in whole brain extracts (n = 9 rats at each time for both TBI levels). Sham-operated animals (n = 9) were used as controls. Results demonstrated that mTBI caused a late increase (48–120 h post injury) of glycolytic gene expression and enzymatic activities, concomitantly with mitochondrial functional recovery (ATP and ATP/ADP normalization). No changes in lactate and PPP genes and enzymes, were accompanied by transient decrease in GSH, NADP+, NADPH and NADPH/NADP+. Animals following sTBI showed early increase (6–24 h post injury) of glycolytic gene expression and enzymatic activities, occurring during mitochondrial malfunctioning (50% decrease in ATP and ATP/ADP). Higher lactate and lower GSH, NADP+, NADPH, NADPH/NADP+ than controls were recorded at anytime post injury (p < 0.01). Both TBI levels caused metabolic and gene changes affecting glucose metabolism. Following mTBI, increased glucose flux through glycolysis is coupled to mitochondrial glucose oxidation. “True” hyperglycolysis occurs only after sTBI, where metabolic changes, caused by depressed mitochondrial phosphorylating capacity, act on genes causing net glycolytic flux increase uncoupled from mitochondrial glucose oxidation.
Keywords: Traumatic brain injury; Glucose dysmetabolism; Glycolysis; Pentose phosphate pathway; Energy metabolism; Mitochondrial dysfunction;
Effect of the pituitary adenylate cyclase-activating polypeptide on the autophagic activation observed in in vitro and in vivo models of Parkinson's disease by Asma Lamine-Ajili; Ahmed M. Fahmy; Myriam Létourneau; David Chatenet; Patrick Labonté; David Vaudry; Alain Fournier (688-695).
Parkinson's disease (PD) is a neurodegenerative disorder that leads to destruction of the midbrain dopaminergic (DA) neurons. This phenomenon is related to apoptosis and its activation can be blocked by the pituitary adenylate cyclase-activating polypeptide (PACAP). Growing evidence indicates that autophagy, a self-degradation activity that cleans up the cell, is induced during the course of neurodegenerative diseases. However, the role of autophagy in the pathogenesis of neuronal disorders is yet poorly understood and the potential ability of PACAP to modulate the related autophagic activation has never been significantly investigated. Hence, we explored the putative autophagy-modulating properties of PACAP in in vitro and in vivo models of PD, using the neurotoxic agents 1-methyl-4-phenylpyridinium (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), respectively, to trigger alterations of DA neurons. In both models, following the toxin exposure, PACAP reduced the autophagic activity as evaluated by the production of LC3 II, the modulation of the p62 protein levels, and the formation of autophagic vacuoles. The ability of PACAP to inhibit autophagy was also observed in an in vitro cell assay by the blocking of the p62-sequestration activity produced with the autophagy inducer rapamycin. Thus, the results demonstrated that autophagy is induced in PD experimental models and that PACAP exhibits not only anti-apoptotic but also anti-autophagic properties.
Keywords: Autophagy; PACAP; Neurodegeneration; Dopaminergic neuron survival; Mitochondrial functions; SH-SY5Y neuroblastoma cell survival;
Enteroendocrine cells are a potential source of serum autotaxin in men by Ruth Bolier; Dagmar Tolenaars; Andreas E. Kremer; Job Saris; Albert Parés; Joanne Verheij; Piter J. Bosma; Ulrich Beuers; Ronald P.J. Oude Elferink (696-704).
Serum autotaxin (ATX) activity is significantly increased in cholestatic patients. Our study aimed to unravel the source(s) of ATX in cholestasis.ATX activity and protein were measured in sera of healthy (n = 33) and cholestatic patients (n = 152), including women with intrahepatic cholestasis of pregnancy. ATX mRNA and protein expression were analyzed in various tissues from mice and men. Induction of ATX activity was assessed in mouse models of extrahepatic (bile duct ligation) and intrahepatic cholestasis (Atp8b1G308V/G308V, 0.1% cholate-supplemented diet). ATX clearance in cholestatic and control mice was assessed after intravenous injection of recombinant ATX. Human hepatic clearance was estimated by comparing ATX activity in portal and hepatic vein serum.Serum ATX activity and ATX protein concentration tightly correlated under all conditions in patients and controls (p < 0.0001). In humans Atx mRNA was highly expressed in small intestine, whereas in mice Atx was expressed mainly in brain and placenta but not in small intestine. Extensive ATX protein expression was identified in human, but not murine intestinal enteroendocrine cells. In murine models of cholestasis and cholestatic pregnancy plasma ATX activity was only mildly elevated (up to 2.1-fold). Atx tissue expression and rATX clearance after parenteral administration did not differ between cholestatic and control mice.Serum ATX activity during cholestasis and itch is enhanced by increased protein concentration rather than enzymatic induction. In mice, clearance of ATX is not affected by cholestasis. Small intestinal ATX expression by enteroendocrine cells might represent an important source of cholestasis-induced serum ATX activity in men.
Keywords: Cholestasis; Autotaxin; Pruritus; Itch; Enteroendocrine cells;
Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects by Nikola Kovářová; Petr Pecina; Hana Nůsková; Marek Vrbacký; Massimo Zeviani; Tomáš Mráček; Carlo Viscomi; Josef Houštěk (705-715).
Mitochondrial protein SURF1 is a specific assembly factor of cytochrome c oxidase (COX), but its function is poorly understood. SURF1 gene mutations cause a severe COX deficiency manifesting as the Leigh syndrome in humans, whereas in mice SURF1 −/− knockout leads only to a mild COX defect. We used SURF1 −/− mouse model for detailed analysis of disturbed COX assembly and COX ability to incorporate into respiratory supercomplexes (SCs) in different tissues and fibroblasts. Furthermore, we compared fibroblasts from SURF1 −/− mouse and SURF1 patients to reveal interspecies differences in kinetics of COX biogenesis using 2D electrophoresis, immunodetection, arrest of mitochondrial proteosynthesis and pulse-chase metabolic labeling.The crucial differences observed are an accumulation of abundant COX1 assembly intermediates, low content of COX monomer and preferential recruitment of COX into I–III2–IVn SCs in SURF1 patient fibroblasts, whereas SURF1 −/− mouse fibroblasts were characterized by low content of COX1 assembly intermediates and milder decrease in COX monomer, which appeared more stable. This pattern was even less pronounced in SURF1 −/− mouse liver and brain. Both the control and SURF1 −/− mice revealed only negligible formation of the I–III2–IVn SCs and marked tissue differences in the contents of COX dimer and III2–IV SCs, also less noticeable in liver and brain than in heart and muscle. Our studies support the view that COX assembly is much more dependent on SURF1 in humans than in mice. We also demonstrate markedly lower ability of mouse COX to form I–III2–IVn supercomplexes, pointing to tissue-specific and species-specific differences in COX biogenesis.
Keywords: Cytochrome c oxidase; Respiratory supercomplexes; Leigh syndrome; SURF1 −/− mouse knockout; Doxycycline; Pulse-chase;
Evaluation of in vivo mitochondrial bioenergetics in skeletal muscle using NMR and optical methods by Matthew D. Campbell; David J. Marcinek (716-724).
It is now clear that mitochondria are involved as either a cause or consequence of many chronic diseases. This central role of the mitochondria is due to their position in the cell as important integrators of cellular energetics and signaling. Mitochondrial function affects many aspects of the cellular environment such as redox homeostasis and calcium signaling, which then also exert control over mitochondrial function. This complex dynamic between mitochondrial function and the cellular environment highlights the value of examining mitochondria in vivo in the intact physiological environment. This review discusses NMR and optical approaches used to measure mitochondria ATP and oxygen fluxes that provide in vivo measures of mitochondrial capacity and quality in animal and human models. Combining these in vivo measurements with more traditional ex vivo analyses can lead to new insights into the importance of the cellular environment in controlling mitochondrial function under pathological conditions. Interpretation and underlying assumptions for each technique are discussed with the goal of providing an overview of some of the most common approaches used to measure in vivo mitochondrial function encountered in the literature.
Keywords: In vivo spectroscopy; Mitochondria; Skeletal muscle; Bioenergetics; NMR; NIRS;
Cytoskeleton deregulation and impairment in amino acids and energy metabolism in early atherosclerosis at aortic tissue with reflection in plasma by Marta Martin-Lorenzo; Laura Gonzalez-Calero; Aroa S. Maroto; Paula J. Martinez; Irene Zubiri; Fernando de la Cuesta; Laura Mourino-Alvarez; Maria G. Barderas; Angeles Heredero; Gonzalo Aldamiz-Echevarría; Fernando Vivanco; Gloria Alvarez-Llamas (725-732).
Cardiovascular disease (CVD) is the leading cause of death globally, being atherosclerosis the main cause. Main risk factors are known and current effort is very much dedicated to improve prevention. However, the asymptomatic and silent course of atherosclerosis hampers an accurate and individualized risk evaluation.Here we investigate subjacent molecular changes taking place in arterial tissue which can be ultimately translated in a measurable fingerprint in plasma.First, we applied a combined approach to find out main molecular alterations at protein and metabolite level in response to early atherosclerosis development in a rabbit model. A potential reflection of all these alterations observed in aortic tissue was investigated in rabbit plasma and further analyzed in a translational study in human plasma from 62 individuals.Data link the structural remodeling taking place in atherosclerotic arteries in terms of loss of contractile properties and favored cellular migration, with an up-regulation of integrin linked kinase, tropomyosin isoform 2 and capping protein gelsolin-like, and a down-regulation of vinculin. A molecular response to oxidative stress is evidenced, involving changes in the glucose metabolism enzymes pyruvate kinase (PKM) and phosphoglycerate kinase (PGK), and pyruvate. Up-regulation of aspartate connects different changes observed in amino acid metabolism and, additionally, alterations in the phosphatidylcholine route of the glycerophospholipid metabolism were found.A specific molecular marker panel composed by PKM, valine and pyruvate is shown here linked to cardiovascular risk.
Keywords: Atherosclerosis; Arteries; Cardiovascular diseases; Metabolome; Plasma;
Notch-dependent EMT is attenuated in patients with aortic aneurysm and bicuspid aortic valve by Aleksandra S. Kostina; Vladimir Е. Uspensky; Olga B. Irtyuga; Elena V. Ignatieva; Olga Freylikhman; Natalia D. Gavriliuk; Olga M. Moiseeva; Sergey Zhuk; Alexey Tomilin; Аnna А. Kostareva; Anna B. Malashicheva (733-740).
Bicuspid aortic valve is the most common congenital heart malformation and the reasons for the aortopathies associated with bicuspid aortic valve remain unclear. NOTCH1 mutations are associated with bicuspid aortic valve and have been found in individuals with various left ventricular outflow tract abnormalities. Notch is a key signaling during cardiac valve formation that promotes the endothelial-to-mesenchymal transition. We address the role of Notch signaling in human aortic endothelial cells from patients with bicuspid aortic valve and aortic aneurysm. Aortic endothelial cells were isolated from tissue fragments of bicuspid aortic valve-associated thoracic aortic aneurysm patients and from healthy donors. Endothelial-to-mesenchymal transition was induced by activation of Notch signaling. Effectiveness of the transition was estimated by loss of endothelial and gain of mesenchymal markers by immunocytochemistry and qPCR. We show that aortic endothelial cells from the patients with aortic aneurysm and bicuspid aortic valve have down regulated Notch signaling and fail to activate Notch-dependent endothelial-to-mesenchymal transition in response to its stimulation by different Notch ligands. Our findings support the idea that bicuspid aortic valve and associated aortic aneurysm is associated with dysregulation of the entire Notch signaling pathway independently on the specific gene mutation.
Keywords: Aorta; Endothelium; Valves; Signal transduction;
Adaptation within mitochondrial oxidative phosphorylation supercomplexes and membrane viscosity during degeneration of dopaminergic neurons in an animal model of early Parkinson's disease by Katarzyna Kuter; Manuela Kratochwil; Klemencja Berghauzen-Maciejewska; Urszula Głowacka; Michiru D. Sugawa; Krystyna Ossowska; Norbert A. Dencher (741-753).
In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neurons in substantia nigra (SN), preventing early diagnosis. Mitochondrial dysfunction was indicated in neuropathological process already at early PD stages. Aging and oxidative stress, the main factors in PD pathogenesis, cause membrane stiffening, which could influence functioning of membrane-bound oxidative phosphorylation (OxPhos) complexes (Cxs) in mitochondria.In 6-OHDA rat model, medium-sized dopaminergic lesion was used to study mitochondrial membrane viscosity and changes at the level of OxPhos Cxs and their higher assembled states—supercomplexes (SCxs), during the early degeneration processes and after it.We observed loss of dopaminergic phenotype in SN and decreased dopamine level in striatum (STR) before actual death of neurons in SN. Behavioural deficits induced by lesion were reversed despite progressing neurodegeneration. Along with degeneration process in STR, mitochondrial Cx I performance and amount decreased in almost all forms of SCxs. Also, progressing decrease of Cx IV performance in SCxs (I1III2IV3–1, I1IV2–1) in STR was observed during degeneration. In SN, SCxs containing Cx I increased protein amount and a shifted individual Cx I1 into superassembled states. Importantly, mitochondrial membrane viscosity changed in parallel with altered SCxs performance.We show for the first time changes at the level of mitochondrial membrane viscosity influencing SCxs function after dopaminergic system degeneration. It implicates that altered mitochondrial membrane viscosity could play an important role in regulation of mitochondria functioning and pathomechanisms of PD. The data obtained are also discussed in relation to compensatory processes observed.
Keywords: Mitochondrial membrane viscosity; OxPhos supercomplex assembly; Neurodegeneration; Parkinson's disease; Compensatory processes;
Phenotypic and clinical implications of variants in the dihydropyrimidine dehydrogenase gene by André B.P. van Kuilenburg; Judith Meijer; Michael W.T. Tanck; Doreen Dobritzsch; Lida Zoetekouw; Lois-Lee Dekkers; Jeroen Roelofsen; Rutger Meinsma; Machteld Wymenga; Wim Kulik; Barbara Büchel; Raoul C.M. Hennekam; Carlo R. Largiadèr (754-762).
Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of the pyrimidine bases uracil, thymine and the antineoplastic agent 5-fluorouracil. Genetic variations in the gene encoding DPD (DPYD) have emerged as predictive risk alleles for 5FU-associated toxicity. Here we report an in-depth analysis of genetic variants in DPYD and their consequences for DPD activity and pyrimidine metabolites in 100 Dutch healthy volunteers. 34 SNPs were detected in DPYD and 15 SNPs were associated with altered plasma concentrations of pyrimidine metabolites. DPD activity was significantly associated with the plasma concentrations of uracil, the presence of a specific DPYD mutation (c.1905 + 1G > A) and the combined presence of three risk variants in DPYD (c.1905 + 1G > A, c.1129-5923C > G, c.2846A > T), but not with an altered uracil/dihydrouracil (U/UH2) ratio. Various haplotypes were associated with different DPD activities (haplotype D3, a decreased DPD activity; haplotype F2, an increased DPD activity). Functional analysis of eight recombinant mutant DPD enzymes showed a reduced DPD activity, ranging from 35% to 84% of the wild-type enzyme. Analysis of a DPD homology model indicated that the structural effect of the novel p.G401R mutation is most likely minor. The clinical relevance of the p.D949V mutation was demonstrated in a cancer patient heterozygous for the c.2846A > T mutation and a novel nonsense mutation c.1681C > T (p.R561X), experiencing severe grade IV toxicity. Our studies showed that the endogenous levels of uracil and the U/UH2 ratio are poor predictors of an impaired DPD activity. Loading studies with uracil to identify patients with a DPD deficiency warrants further investigation.
Keywords: Dihydropyrimidine dehydrogenase; DPYD; 5-Fluorouracil; Pharmacogenetics; Pyrimidine metabolism;
Chronic heart failure: Ca2 +, catabolism, and catastrophic cell death by Geoffrey W. Cho; Francisco Altamirano; Joseph A. Hill (763-777).
Robust successes have been achieved in recent years in conquering the acutely lethal manifestations of heart disease. Many patients who previously would have died now survive to enjoy happy and productive lives. Nevertheless, the devastating impact of heart disease continues unabated, as the spectrum of disease has evolved with new manifestations. In light of this ever-evolving challenge, insights that culminate in novel therapeutic targets are urgently needed. Here, we review fundamental mechanisms of heart failure, both with reduced (HFrEF) and preserved (HFpEF) ejection fraction. We discuss pathways that regulate cardiomyocyte remodeling and turnover, focusing on Ca2 + signaling, autophagy, and apoptosis. In particular, we highlight recent insights pointing to novel connections among these events. We also explore mechanisms whereby potential therapeutic approaches targeting these processes may improve morbidity and mortality in the devastating syndrome of heart failure.
Keywords: Heart failure; Remodeling; Calcium homeostasis; Autophagy; Apoptosis;
Role of P-glycoprotein in mediating rivastigmine effect on amyloid-β brain load and related pathology in Alzheimer's disease mouse model by Loqman A. Mohamed; Jeffrey N. Keller; Amal Kaddoumi (778-787).
Recently, we showed that rivastigmine decreased amyloid-β (Aβ) brain load in aged rats by enhancing its clearance across the blood–brain barrier (BBB) via upregulation of P-glycoprotein (P-gp) and low-density lipoprotein receptor-related protein 1 (LRP1). Here, we extend our previous work to clarify P-gp role in mediating rivastigmine effect on Aβ brain levels and neuroprotection in a mouse model of Alzheimer's disease (AD) that expresses different levels of P-gp. APPSWE mice were bred with mdr1a/b knockout mice to produce littermates that were divided into three groups; APP+/mdr1+/+, APP+/mdr1+/− and APP+/mdr1−/−. Animals received rivastigmine treatment (0.3 mg/kg/day) or vehicle for 8 weeks using Alzet osmotic mini-pumps. ELISA analysis of brain homogenates for Aβ showed rivastigmine treatment to significantly decrease Aβ brain load in APP+/mdr1+/+ by 25% and in APP+/mdr1+/− mice by 21% compared to their vehicle treated littermates, but not in APP+/mdr1−/− mice. In addition, rivastigmine reduced GFAP immunostaining of astrocytes by 50% and IL-1β brain level by 43% in APP+/mdr1+/+ mice, however its effect was less pronounced in P-gp knockout mice. Moreover, rivastigmine demonstrated a P-gp expression dependent neuroprotective effect that was highest in APP+/mdr1+/+ > APP+/mdr1+/−>APP+/mdr1−/− as determined by expression of synaptic markers PSD-95 and SNAP-25 using Western blot analysis. Collectively, our results suggest that P-gp plays important role in mediating rivastigmine non-cholinergic beneficial effects, including Aβ brain load reduction, neuroprotective and anti-inflammatory effects in the AD mouse models.
Keywords: Rivastigmine; P-glycoprotein; Alzheimer's disease; Amyloid-beta; Neuroprotection; Astrogliosis;
HSPA6 is an ulcerative colitis susceptibility factor that is induced by cigarette smoke and protects intestinal epithelial cells by stabilizing anti-apoptotic Bcl-XL by Anouk Regeling; Floris Imhann; Haukeline H. Volders; Tjasso Blokzijl; Vincent W. Bloks; Rinse K. Weersma; Gerard Dijkstra; Klaas Nico Faber (788-796).
Cigarette smoking ameliorates ulcerative colitis (UC) and aggravates Crohn's disease (CD). Cigarette smoke suppresses inflammation-induced apoptosis in intestinal epithelial cells (DLD-1), which may explain its protective effect in UC. Here, we performed transcriptome profiling of cigarette smoke extract (CSE)-exposed DLD-1 and Jurkat cells (T-lymphocytes) and related this to UC susceptibility genes with protective functions in the intestinal epithelium.CSE-regulated genes in DLD-1 and Jurkat cells were identified by Illumina microarrays and compared to genes in UC susceptibility loci. Colon biopsies were analyzed by immunohistochemistry for cell-specific expression of HSPA6. CSE-induced gene expression was analyzed by Q-PCR, Western blotting and immunofluorescence microscopy. Protein (HSPA6/Bcl-XL) interactions were analyzed by immunoprecipitation.CSE changed the expression of 536 and 2560 genes in DLD-1 and Jurkat cells, respectively. The “response to unfolded protein” was one of the most significantly affected gene sets with prominent induction (20.3-fold) of heat shock protein A6 (HSPA6). Six CSE-induced genes in DLD-1 cells were located in UC-susceptibility loci, including HSPA6 (rs1801274). HSPA6 is highly expressed in the human colonic epithelium. CSE caused a dose-dependent strong (> 100-fold at 30% CSE for 6 h), but transient induction of HSPA6 mRNA and protein in DLD-1 cells. HSPA6 co-immune precipitated with anti-apoptotic Bcl-XL, protein levels of which were increased while mRNA levels were unchanged. HSPA6 is a cigarette smoke-induced UC-susceptibility gene. The HSPA6 risk locus is associated with decreased HSPA6 expression. HSPA6 provides epithelial protection by stabilizing anti-apoptotic Bcl-XL, thereby contributing to the beneficial effect of cigarette smoking in UC.
Keywords: Ulcerative colitis; Cigarette smoke; Intestinal epithelium; Heat shock protein A6; Apoptosis;
Evidence for synergistic action of transthyretin and IGF-I over the IGF-I receptor by Marta Vieira; Sónia S. Leal; Cláudio M. Gomes; Maria João Saraiva (797-804).
Transthyretin (TTR) has a neuroprotective role in the central nervous system (CNS) in Alzheimer's disease (AD) and cerebral ischemia. Increased levels of TTR and activated insulin-like growth factor I receptor (IGF-IR) are associated with reduced neurodegeneration in an AD mouse model. In the present study, we found that TTR and IGF-I have a synergistic effect on activation of one of the IGF-IR signaling pathways. Hippocampus of TTR null mice present decreased levels of phosphorylated IGF-IR and Akt when compared with TTR wild type littermate animals. Cell studies reveal the synergistic effect of TTR and IGF-I in promoting IGF-IR signaling even under glutamate induced toxicity. TTR:IGF-IR complexes are identified and a bio-layer interferometry assay demonstrated an interaction between TTR and IGF-IR with a K D ranging from 99 to 744 nM. In summary, our results point to a new TTR role through the IGF-I axis, mediated through TTR-IGF-IR interactions.
Keywords: Ischemia; Glutamate; Synergy; Protein–protein interaction;
High glucose and hyperglycemic sera from type 2 diabetic patients impair DC differentiation by inducing ROS and activating Wnt/β-catenin and p38 MAPK by Maria Saveria Gilardini Montani; Marisa Granato; Laura Cuomo; Sandro Valia; Livia Di Renzo; Gabriella D'Orazi; Alberto Faggioni; Mara Cirone (805-813).
Type 2 is the type of diabetes with higher prevalence in contemporary time, representing about 90% of the global cases of diabetes. In the course of diabetes, several complications can occur, mostly due to hyperglycemia and increased reactive oxygen species (ROS) production. One of them is represented by an increased susceptibility to microbial infections and by a reduced capacity to clear them. Therefore, knowing the impact of hyperglycemia on immune system functionality is of utmost importance for the management of the disease. In this study, we show that medium containing high glucose reduced the in-vitro differentiation of monocytes into functional DCs and their activation mediated by PAMPs or DAMPs. Most importantly, the same effects were mediated by the hyperglycemic sera derived by type 2 diabetic patients, mimicking a more physiologic condition. DC dysfunction caused by hyperglycemia may be involved in the inefficient control of infections observed in diabetic patients, given the pivotal role of these cells in both the innate and adaptive immune response. Searching for the molecular mechanisms underlying DC dysfunction, we found that canonical Wnt/β-catenin and p38 MAPK pathways were activated in the DCs differentiated either in the presence of high glucose or of hyper-glycemic sera. Interestingly, the activation of these pathways and the DC immune dysfunction were partially counteracted by the anti-oxidant quercetin, a flavonoid already known to exert several beneficial effects in diabetes.Display Omitted
Keywords: DC; Hyperglycemia; ROS; Wnt/β-catenin; p38 MAPK; Quercetin;
Multiple faces of dynamin-related protein 1 and its role in Alzheimer's disease pathogenesis by Ramesh Kandimalla; P. Hemachandra Reddy (814-828).
Mitochondria play a large role in neuronal function by constantly providing energy, particularly at synapses. Recent studies suggest that amyloid beta (Aβ) and phosphorylated tau interact with the mitochondrial fission protein, dynamin-related protein 1 (Drp1), causing excessive fragmentation of mitochondria and leading to abnormal mitochondrial dynamics and synaptic degeneration in Alzheimer's disease (AD) neurons. Recent research also revealed Aβ-induced and phosphorylated tau-induced changes in mitochondria, particularly affecting mitochondrial shape, size, distribution and axonal transport in AD neurons. These changes affect mitochondrial health and, in turn, could affect synaptic function and neuronal damage and ultimately leading to memory loss and cognitive impairment in patients with AD. This article highlights recent findings in the role of Drp1 in AD pathogenesis. This article also highlights Drp1 and its relationships to glycogen synthase kinase 3, cyclin-dependent kinase 5, p53, and microRNAs in AD pathogenesis.
Keywords: Alzheimer's disease; Drp1; GSK3β; mitochondria; p53; CDK5; miRNA;
Mitochondrial DNA haplogroups modify the risk of osteoarthritis by altering mitochondrial function and intracellular mitochondrial signals by Hezhi Fang; Fengjiao Zhang; Fengjie Li; Hao Shi; Lin Ma; Miaomiao Du; Yanting You; Ruyi Qiu; Hezhongrong Nie; Lijun Shen; Yidong Bai; Jianxin Lyu (829-836).
Haplogroup G predisposes one to an increased risk of osteoarthritis (OA) occurrence, while haplogroup B4 is a protective factor against OA onset. However, the underlying mechanism is not known. Here, by using trans-mitochondrial technology, we demonstrate that the activity levels of mitochondrial respiratory chain complex I and III are higher in G cybrids than in haplogroup B4. Increased mitochondrial oxidative phosphorylation (OXPHOS) promotes mitochondrial-related ATP generation in G cybrids, thereby shifting the ATP generation from glycolysis to OXPHOS. Furthermore, we found that lower glycolysis in G cybrids decreased cell viability under hypoxia (1% O2) compared with B4 cybrids. In contrast, G cybrids have a lower NAD+/NADH ratio and less generation of reactive oxygen species (ROS) under both hypoxic (1% O2) and normoxic (20% O2) conditions than B4 cybrids, indicating that mitochondrial-mediated signaling pathways (retrograde signaling) differ between these cybrids. Gene expression profiling of G and B4 cybrids using next-generation sequencing technology showed that 404 of 575 differentially expressed genes (DEGs) between G and B4 cybrids are enriched in 17 pathways, of which 11 pathways participate in OA. Quantitative reverse transcription PCR (qRT-PCR) analyses confirmed that G cybrids had lower glycolysis activity than B4 cybrids. In addition, we confirmed that the rheumatoid arthritis pathway was over-activated in G cybrids, although the remaining 9 pathways were not further tested by qRT-PCR. In conclusion, our findings indicate that mtDNA haplogroup G may increase the risk of OA by shifting the metabolic profile from glycolysis to OXPHOS and by over-activating OA-related signaling pathways.
Keywords: Mitochondrial DNA haplogroup; Osteoarthritis; Chondrocyte; Retrograde signaling;
Oncogenic circuit constituted by Ser31-HBx and Akt increases risks of chronic hepatitis and hepatocellular carcinoma by Wei-Ping Lee; Keng-Hsin Lan; Chung-Pin Li; Yee Chao; Han-Chieh Lin; Shou-Dong Lee (837-849).
The X protein of hepatitis B virus (HBx) has been specifically implicated in the development of hepatocellular carcinoma (HCC). Clinical associations of HBx isoforms with chronic hepatitis and HCC have not been well studied. HBx has two roles in liver cells, namely pro-apoptotic and anti-apoptotic. In this report, we examined the role of Ser31-HBx in HCC and chronic hepatitis. Using the case–control study, we determined risks of chronic hepatitis and HCC conferred by hepatitis B virus (HBV) containing Ser31-HBx that was phosphorylated by Akt. Ser31-HBx isoforms conferred 3.23-fold risk of HCC in male and 3.36-fold risk in female. Ser31 isoforms were associated with 3.12-fold risk of chronic hepatitis and 3.43-fold risk of cirrhosis and also associated with higher HBV viral load and replication efficiency and lower rate of HBe loss. To determine the mechanism, we found that Ser31-HBx constituted an oncogenic circuit with Akt and cooperated with ras to transform NIH3T3 cells in contrast to non-Ser31-HBxs that did not transduce oncogenic signals. Our results give a clue to account for an underlying cause of HBx-mediated hepatocarcinogenesis. It appears that Ser31 phosphorylation of HBx by Akt plays an important role. The current study provides an example of association of HBV genome variations with risks of HCC and chronic hepatitis
Keywords: HBx; Akt; Phosphorylation; Hepatocellular carcinoma;
Necrostatin-1 rescues mice from lethal irradiation by Zhentai Huang; Michael Epperly; Simon C. Watkins; Joel S. Greenberger; Valerian E. Kagan; Hülya Bayır (850-856).
There is an emerging need in new medical products that can mitigate and/or treat the short- and long-term consequences of radiation exposure after a radiological or nuclear terroristic event. The direct effects of ionizing radiation are realized primarily via apoptotic death pathways in rapidly proliferating cells within the initial 1–2 days after the exposure. However later in the course of the radiation disease necrotic cell death may ensue via direct and indirect pathways from increased generation of pro-inflammatory cytokines. Here we evaluated radiomitigative potential of necrostatin-1 after total body irradiation (TBI) and the contribution of necroptosis to cell death induced by radiation. Circulating TNFα levels were increased starting on d1 after TBI and associated with increased plasmalemma permeability in ileum of irradiated mice. Necrostatin-1 given iv. 48 h after 9.5 Gy TBI attenuated radiation-induced receptor interacting protein kinase 3 (RIPK3) serine phosphorylation in ileum and improved survival vs. vehicle. Utilizing apoptosis resistant cytochrome c−/− cells, we showed that radiation can induce necroptosis, which is attenuated by RNAi knock down of RIPK1 and RIPK3 or by treatment with necrostatin-1 or -1s whereas 1-methyl-L-tryptophan, an indoleamine-2,3-dioxygenase inhibitor, did not exhibit radiomitigative effect. This suggests that the beneficial effect of necrostatin-1 is likely through inhibition of RIPK1-mediated necroptotic pathway. Overall, our data indicate that necroptosis, a form of programmed necrosis, may play a significant role in cell death contributing to radiation disease and mortality. This study provides a proof of principle that necrostatin-1 and perhaps other RIPK1 inhibitors are promising therapeutic agents for radiomitigation after TBI.
Keywords: Mitigation; Propidium iodide; IL-1α; IL-6; IL-17; 7-Cl-O-Nec-1;