BBA - Molecular Basis of Disease (v.1863, #1)
Reviewer Acknowledgement (iii-xiii).
Editorial Board (i).
Publisher Note (xiv).
Fluctuations in glucose levels induce glial toxicity with glutamatergic, oxidative and inflammatory implications by André Quincozes-Santos; Larissa Daniele Bobermin; Adriano M. de Assis; Carlos-Alberto Gonçalves; Diogo Onofre Souza (1-14).
Astrocytes are dynamic cells that maintain brain homeostasis by regulating neurotransmitter systems, antioxidant defenses, inflammatory responses and energy metabolism. Astroglial cells are also primarily responsible for the uptake and metabolism of glucose in the brain. Diabetes mellitus (DM) is a pathological condition characterized by hyperglycemia and is associated with several changes in the central nervous system (CNS), including alterations in glial function. Classically, excessive glucose concentrations are used to induce experimental models of astrocyte dysfunction; however, hypoglycemic episodes may also cause several brain injuries. The main focus of the present study was to evaluate how fluctuations in glucose levels induce cytotoxicity. The culture medium of astroglial cells was replaced twice as follows: (1) from 6 mM (control) to 12 mM (high glucose), and (2) from 12 mM to 0 mM (glucose deprivation). Cell viability, mitochondrial function, oxidative/nitrosative stress, glutamate metabolism, inflammatory responses, nuclear factor κB (NFκB) transcriptional activity and p38 mitogen-activated protein kinase (p38 MAPK) levels were assessed. Our in vitro experimental model showed that up and down fluctuations in glucose levels decreased cell proliferation, induced mitochondrial dysfunction, increased oxidative/nitrosative stress with consequent cellular biomolecular damage, impaired glutamate metabolism and increased pro-inflammatory cytokine release. Additionally, activation of the NFκB and p38 signaling pathways were putative mechanisms of the effects of glucose fluctuations on astroglial cells. In summary, for the first time, we show that changes in glucose concentrations, from high-glucose levels to glucose deprivation, exacerbate glial injury.
Keywords: C6 cells; High glucose medium; Glucose deprivation; Oxidative/nitrosative stress; Neuroinflammation; NFκB signaling;
Exploring Splicing-Switching Molecules For Seckel Syndrome Therapy by Daniela Scalet; Dario Balestra; Sara Rohban; Matteo Bovolenta; Daniela Perrone; Francesco Bernardi; Stefano Campaner; Mirko Pinotti (15-20).
The c.2101 A > G synonymous change (p.G674G) in the gene for ATR, a key player in the DNA-damage response, has been the first identified genetic cause of Seckel Syndrome (SS), an orphan disease characterized by growth and mental retardation. This mutation mainly causes exon 9 skipping, through an ill-defined mechanism.Through ATR minigene expression studies, we demonstrated that the detrimental effect of this mutation (6 ± 1% of correct transcripts only) depends on the poor exon 9 definition (47 ± 4% in the ATRwt context), because the change was ineffective when the weak 5′ or the 3′ splice sites (ss) were strengthened (scores from 0.54 to 1) by mutagenesis. Interestingly, the exonic c.2101 A nucleotide is conserved across species, and the SS-causing mutation is predicted to concurrently strengthen a Splicing Silencer (ESS) and weaken a Splicing Enhancer (ESE). Consistently, the artificial c.2101 A > C change, predicted to weaken the ESE only, moderately impaired exon inclusion (28 ± 7% of correct transcripts). The observation that an antisense oligonucleotide (AONATR) targeting the c.2101 A position recovers exon inclusion in the mutated context supports a major role of the underlying ESS.A U1snRNA variant (U1ATR) designed to perfectly base-pair the weak 5’ss, rescued exon inclusion (63 ± 3%) in the ATRSS-allele. Most importantly, upon lentivirus-mediated delivery, the U1ATR partially rescued ATR mRNA splicing (from ~ 19% to ~ 54%) and protein (from negligible to ~ 6%) in embryonic fibroblasts derived from humanized ATRSS mice.Altogether these data elucidate the molecular mechanisms of the ATR c.2101 A > G mutation and identify two potential complementary RNA-based therapies for Seckel syndrome.Display Omitted
Keywords: (up to 6) Seckel syndrome-1; Exonic splicing silencer; modified U1snRNA; Antisense oligonucleotide; correction approaches;
Parkin elimination of mitochondria is important for maintenance of lens epithelial cell ROS levels and survival upon oxidative stress exposure by Lisa Brennan; Josef Khoury; Marc Kantorow (21-32).
Age-related cataract is associated with oxidative stress and death of lens epithelial cells (LECs) whose survival is dependent on functional mitochondrial populations. Oxidative stress-induced depolarization/damage of LEC mitochondria results in increased reactive oxygen species (ROS) levels and cell death suggesting the need for a LEC mechanism to remove mitochondria depolarized/damaged upon oxidative stress exposure to prevent ROS release and LEC death. To date, a mechanism(s) for removal of depolarized/damaged LEC mitochondria has yet to be identified and the importance of eliminating oxidative stress-damaged mitochondria to prevent LEC ROS release and death has not been established. Here, we demonstrate that Parkin levels increase in LECs exposed to H2O2-oxidative stress. We establish that Parkin translocates to LEC mitochondria depolarized upon oxidative stress exposure and that Parkin recruits p62/SQSTM1 to depolarized LEC mitochondria. We demonstrate that translocation of Parkin results in the elimination of depolarized/damaged mitochondria and that Parkin clearance of LEC mitochondria is dependent on its ubiquitin ligase activity. Importantly, we demonstrate that Parkin elimination of damaged LEC mitochondria results in reduced ROS levels and increased survival upon oxidative stress exposure. These results establish that Parkin functions to eliminate LEC mitochondria depolarized/damaged upon oxidative stress exposure and that elimination of damaged mitochondria by Parkin is important for LEC homeostasis and survival. The data also suggest that mitochondrial quality control by Parkin could play a role in lens transparency.
Keywords: Oxidative stress; Reactive oxygen species; Mitochondria; Lens cell survival; Cataract;
Therapeutic relevance of mTOR inhibition in murine succinate semialdehyde dehydrogenase deficiency (SSADHD), a disorder of GABA metabolism by K.R. Vogel; G.R. Ainslie; E.E.W. Jansen; G.S. Salomons; K.M. Gibson (33-42).
Aldehyde dehydrogenase 5a1-deficient (aldh5a1 −/− ) mice, the murine orthologue of human succinic semialdehyde dehydrogenase deficiency (SSADHD), manifest increased GABA (4-aminobutyric acid) that disrupts autophagy, increases mitochondria number, and induces oxidative stress, all mitigated with the mTOR (mechanistic target of rapamycin) inhibitor rapamycin . Because GABA regulates mTOR, we tested the hypothesis that aldh5a1 −/− mice would show altered levels of mRNA for genes associated with mTOR signaling and oxidative stress that could be mitigated by inhibiting mTOR. We observed that multiple metabolites associated with GABA metabolism (γ-hydroxybutyrate, succinic semialdehyde, D-2-hydroxyglutarate, 4,5-dihydrohexanoate) and oxidative stress were significantly increased in multiple tissues derived from aldh5a1 −/− mice. These metabolic perturbations were associated with decreased levels of reduced glutathione (GSH) in brain and liver of aldh5a1 −/− mice, as well as increased levels of adducts of the lipid peroxidation by-product, 4-hydroxy-2-nonenal (4-HNE). Decreased liver mRNA levels for multiple genes associated with mTOR signaling and oxidative stress parameters were detected in aldh5a1 −/− mice, and several were significantly improved with the administration of mTOR inhibitors (Torin 1/Torin 2). Western blot analysis of selected proteins corresponding to oxidative stress transcripts (glutathione transferase, superoxide dismutase, peroxiredoxin 1) confirmed gene expression findings. Our data provide additional preclinical evidence for the potential therapeutic efficacy of mTOR inhibitors in SSADHD.
Keywords: GABA; Succinic semialdehyde dehydrogenase deficiency; mTOR; Torin 1; Torin 2; Oxidative stress;
Regulation of proteasome activity by P2Y2 receptor underlies the neuroprotective effects of extracellular nucleotides by Laura de Diego-García; Mercedes Ramírez-Escudero; Álvaro Sebastián-Serrano; Juan Ignacio Diaz-Hernández; Jesús Pintor; José J. Lucas; Miguel Díaz-Hernández (43-51).
The Ubiquitin-Proteasome System (UPS) is essential for the regulation of the cellular proteostasis. Indeed, it has been postulated that an UPS dysregulation is the common mechanism that underlies several neurological disorders. Considering that extracellular nucleotides, through their selective P2Y2 receptor (P2Y2R), play a neuroprotective role in various neurological disorders that course with an UPS impairment, we wonder if this neuroprotective capacity resulted from their ability to modulate the UPS. Using a cellular model expressing two different UPS reporters, we found that the stimulation of P2Y2R by its selective agonist Up4U induced a significant reduction of UPS reporter levels. This reduction was due to an increase in two of the three peptidase proteasome activities, chymotrypsin and postglutamyl, caused by an increased expression of proteasome constitutive catalytic subunits β1 and β5. The intracellular signaling pathway involved required the activation of IP3/MEK1/2/ERK but was independent of PKC or PKA. Interestingly, the P2Y2R activation was able to revert both UPS-reporter accumulation and the cell death induced by a prolonged inhibition of UPS. Finally, we also observed that intracerebroventricular administration of Up4U induced a significant increase both of chymotrypsin and postglutamyl activities as well as an increased expression of proteasome subunits β1 and β5 in the hippocampus of wild-type mice, but not in P2Y2R KO mice. All these results strongly suggest that the capacity to modulate the UPS activity via P2Y2R is the molecular mechanism which is how the nucleotides play a neuroprotective role in neurological disorders.
Keywords: Ubiquitin-proteasome-system; P2Y2 receptor; Up4U; Neurological disorders; Chymotrypsin-like activity; Postglutamyl-like activity;
A type VII collagen subdomain mutant is thermolabile and shows enhanced proteolytic degradability — Implications for the pathogenesis of recessive dystrophic epidermolysis bullosa? by Cordula Windler; Ulrike Hermsdorf; Jürgen Brinckmann; Karsten Seeger (52-59).
Type VII collagen is the major constituent of anchoring fibrils. It has a central collagenous domain that is surrounded by a small C-terminal non-collagenous domain (NC2) and a large N-terminal non-collagenous (NC1) domain. Mutations in type VII collagen can lead to hereditary skin blistering disease dystrophic epidermolysis bullosa (DEB). Most of the pathogenic missense mutations are within the collagenous domain. NC1 domain mediates interactions with other extracellular matrix molecules and only very few missense mutations within NC1 causing DEB have been reported. Interestingly, fibronectin III like (FNIII) domain 8 in the human protein can harbour different mutations at position 886 with one (R886P) leading to recessive DEB, whereas the others do not.We characterized subdomains of murine NC1, the FNIII domains 7–8, and the individual domains FNIII7 and FNIII8 by NMR- and CD-spectroscopy. We analysed the influence on stability for a mutation causing DEB and a non-pathogenic mutation. Whereas the silent mutation behaves as the wild type, the pathogenic mutation leads to a dramatic decrease in thermal stability of the FNIII8 domain. The melting temperature lowered from 77 °C to 40 °C compared to the wild type protein. This renders the domain susceptible to protease cleavage which could be shown by degradation tests with cathepsin G, cathepsin K, and MMP9. Our data show partial unfolding of type VII collagen due to the mutation causes an increased degradation. This could lead to skin blistering and opens new concomitant treatment options in some types of type VII collagen related skin blistering diseases.Display Omitted
Keywords: Type VII collagen; Dystrophic epidermolysis bullosa; Protease cleavage;
A mouse model of aniridia reveals the in vivo downstream targets of Pax6 driving iris and ciliary body development in the eye by Xia Wang; Xianghong Shan; Cheryl Y. Gregory-Evans (60-67).
The Pax6 transcription factor is essential for development of the brain, eye, olfactory and endocrine systems. Haploinsufficiency of PAX6 in humans and mice causes the congenital condition aniridia, with defects in each of these organs and systems. Identification of the PAX6 transcription networks driving normal development is therefore critical in understanding the pathophysiology observed with loss-of-function defects. Here we have focused on identification of the downstream targets for Pax6 in the developing iris and ciliary body, where we used laser capture microdissection in mouse eyes from E12.5–E16.5, followed by chromatin immunoprecipitation, promoter-reporter assays and immunohistochemistry. We identified 6 differentially expressed genes between wildtype and Pax6 heterozygous mouse tissues and demonstrated that Bmp4, Tgfβ2, and Foxc1 were direct downstream targets of Pax6 in developing iris/ciliary body. These results improve our understanding of how mutations in Bmp4, Tgfβ2, and Foxc1 result in phenocopies of the aniridic eye disease and provide possible targets for therapeutic intervention.
Keywords: Pax6; Aniridia; Iris; Transcription factor; Downstream target;
Mitochondrial peroxiredoxins are essential in regulating the relationship between Drosophila immunity and aging by Olena Odnokoz; Kyle Nakatsuka; Vladimir I. Klichko; Jacqueline Nguyen; Liz Calderon Solis; Kaitlin Ostling; Marziyeh Badinloo; William C. Orr; Svetlana N. Radyuk (68-80).
Previously, we have shown that flies under-expressing the two mitochondrial peroxiredoxins (Prxs), dPrx3 and dPrx5, display increases in tissue-specific apoptosis and dramatically shortened life span, associated with a redox crisis, manifested as changes in GSH:GSSG and accumulation of protein mixed disulfides. To identify specific pathways responsible for the observed biological effects, we performed a transcriptome analysis. Functional clustering revealed a prominent group enriched for immunity-related genes, including a considerable number of NF-kB-dependent antimicrobial peptides (AMP) that are up-regulated in the Prx double mutant. Using qRT-PCR analysis we determined that the age-dependent changes in AMP levels in mutant flies were similar to those observed in controls when scaled to percentage of life span. To further clarify the role of Prx-dependent mitochondrial signaling, we expressed different forms of dPrx5, which unlike the uniquely mitochondrial dPrx3 is found in multiple subcellular compartments, including mitochondrion, nucleus and cytosol. Ectopic expression of dPrx5 in mitochondria but not nucleus or cytosol partially extended longevity under normal or oxidative stress conditions while complete restoration of life span occurred when all three forms of dPrx5 were expressed from the wild type dPrx5 transgene. When dPrx5 was expressed in mitochondria or in all three compartments, it substantially delayed the development of hyperactive immunity while expression of cytosolic or nuclear forms had no effect on the immune phenotype. The data suggest a critical role of mitochondria in development of chronic activation of the immune response triggered by impaired redox control.
Keywords: Peroxiredoxin; Mitochondria; Immunity; Aging; Redox; Drosophila;
Sodium/proton exchanger isoform 1 regulates intracellular pH and cell proliferation in human ovarian cancer by Carlos Sanhueza; Joaquín Araos; Luciano Naranjo; Fernando Toledo; Ana R Beltrán; Marco A Ramírez; Jaime Gutiérrez; Fabián Pardo; Andrea Leiva; Luis Sobrevia (81-91).
Cancer cells generate protons (H+) that are extruded to the extracellular medium mainly via the Na+/H+ exchanger 1 (NHE1), which regulates intracellular pH (pHi) and cell proliferation. In primary cultures of human ascites-derived ovarian cancer cells (haOC) we assayed whether NHE1 was required for pHi modulation and cell proliferation. Human ovary expresses NHE1, which is higher in haOC and A2780 (ovarian cancer cells) compared with HOSE cells (normal ovarian cells). Basal pHi and pHi recovery (following a NH4Cl pulse) was higher in haOC and A2780, compared with HOSE cells. Zoniporide (NHE1 inhibitor) caused intracellular acidification and pHi recovery was independent of intracellular buffer capacity, but reduced in NHE1 knockdown A2780 cells. Zoniporide reduced the maximal proliferation capacity, cell number, thymidine incorporation, and ki67 (marker of proliferation) fluorescence in haOC cells. SLC9A1 (for NHE1) amplification associated with lower overall patient survival. In conclusion, NHE1 is expressed in human ovarian cancer where it has a pro-proliferative role. Increased NHE1 expression and activity constitute an unfavourable prognostic factor in these patients.
Keywords: NHE1; pHi; Human; Ovarian cancer; Cell proliferation;
TNFa knockdown in the retina promotes cone survival in a mouse model of autosomal dominant retinitis pigmentosa by Tapasi Rana; Pravallika Kotla; Roderick Fullard; Marina Gorbatyuk (92-102).
Expression of T17M rhodopsin (T17M) in rods activates the Unfolded Protein Response (UPR) and leads to the development of autosomal dominant retinitis pigmentosa (adRP). The rod death occurs in adRP retinas prior to cone photoreceptor death, so the mechanism by which cone photoreceptors die remains unclear. Therefore, the goal of the study was to verify whether UPR in rods induces TNFa-mediated signaling to the cones and to determine whether the TNFa deficit could prevent adRP cone cell death.Primary rod photoreceptors and cone-derived 661W cells transfected with siRNA against TNFa were treated with tunicamycin to mimic activation of UPR in T17M retinas expressing normal and reduced TNFa levels. The 661W cells were then exposed to recombinant TNFa to evaluate cell viability. In vivo, the role of TNFa was assessed in T17M TNFa+/− mice by electroretinography, optical coherence tomography, histology, immunohistochemistry, and a cytokine enzyme-linked immunosorbent assay.Rods overexpressed and secreted TNFa in response to UPR activation. The recombinant TNFa treatment lowered the number of viable cones, inducing cell death through elevation of pro-inflammatory cytokines and caspase-3/7 activity. The TNFa deficiency significantly protected adRP retinas. The photopic ERG amplitudes and the number of surviving cones dramatically increased in T17M TNFa+/− mice. This neuroprotection was associated with a reduced level of pro-inflammatory cytokines.Our results indicate that rod photoreceptors, following UPR activation during adRP progression, secrete TNFa and signal a self-destructive program to the cones, resulting in their cell death. TNFa therefore holds promise as a therapeutic target for treatment of adRP.
Keywords: T17M rhodopsin; Retinal degeneration; Transgenic mice; Unfolded protein response; Tumor necrosis factor; Cone survival;
Methionine synthase and methionine synthase reductase interact with MMACHC and with MMADHC by Christine Bassila; Rose Ghemrawi; Justine Flayac; D. Sean Froese; Matthias R. Baumgartner; Jean-Louis Guéant; David Coelho (103-112).
An increasing number of studies indicate that each step of the intracellular processing of vitamin B12 or cobalamin (Cbl) involves protein-protein interactions. We have previously described a novel interaction between methionine synthase (MS) and MMACHC and its effect on the regulation of MMACHC activity. Our goal is to further characterize the interactions of MS with other potential partners in a so-called MS interactome. We dissected the interactions and their alterations by co-immunoprecipitation and DuoLink proximity ligation assays in fibroblasts with cblG, cblE, and cblC genetic defects affecting respectively the expression of MS, methionine synthase reductase (MSR) and MMACHC and in HepG2 cells transfected with corresponding siRNAs. We observed the known interactions of MS with MSR and with MMACHC as well as MMADHC with MMACHC, but we also observed novel interactions for MSR with MMACHC and with MMADHC and MS with MMADHC. Furthermore, we show that the absence of MS or MMACHC expression disrupts the interactions between the other interactome members, in cblC and cblG fibroblasts and in HepG2 cells transfected with siRNAs. Our data show that the processing of Cbl in cytoplasm occurs in a multiprotein complex composed of at least MS, MSR, MMACHC and MMADHC, which could contribute to shuttle safely and efficiently Cbl towards MS. Our data suggest that defective protein-protein interactions among key players of this pathway could contribute to the molecular mechanisms of the cblC, cblG and cblE genetic defects and provide novel insights into our understanding of the pathophysiology of inherited disorders of Cbl metabolism.
Keywords: Rare disease; Vitamin B12; Methionine synthase; Methionine synthase reductase; MMACHC; MMADHC;
Tyrosine hydroxylase haploinsufficiency prevents age-associated arterial pressure elevation and increases half–life in mice by Luis Gamella-Pozuelo; María T Grande; Milagros Clemente-Lorenzo; Cayetana Murillo-Gómez; Flora De Pablo; José M López-Novoa; Catalina Hernández-Sánchez (113-120).
Catecholamines are essential for the maintenance of physiological homeostasis under basal and stress conditions. We aim to determine the impact of deletion of a single allele of the tyrosine hydroxylase (Th) gene might have on aging arterial pressure and life-span. We found that Th haploinsufficiency prevents age-associated increase of arterial pressure (AP) in mature adult mice, and it results in the extension of the half-life of T h-heterozygous (TH-HET) mice respect to their wild-type (WT) littermates. Heart performance was similar in both genotypes. To further investigate the lack of increase in AP with age in TH-HET mice, we measured the AP response to intra-peritoneal administration of substances involved in AP regulation. The response to acetylcholine and the basal sympathetic tone were similar in both genotypes, while norepinephrine had a greater pressor effect in TH-HET mice, which correlated with altered adrenoreceptor expression in blood vessels and the heart. Furthermore, sympatho-adrenomedular response to stress was attenuated in TH-HET mice. Plasma catecholamine levels and urine glucose increased markedly in WT but not in TH-HET mice after stress. Our results showed that TH-HET mice are resistant to age-associated hypertension, present a reduction in the sympathetic response to stress and display an extended half-life.
Keywords: Catecholamines; Tyrosine hydroxylase; Hypertension; Stress; Life-span;
Mouse lysine catabolism to aminoadipate occurs primarily through the saccharopine pathway; implications for pyridoxine dependent epilepsy (PDE) by Izabella Agostinho Pena; Lygia Azevedo Marques; Ângelo B.A. Laranjeira; José A. Yunes; Marcos N. Eberlin; Alex MacKenzie; Paulo Arruda (121-128).
Lysine is catabolized in mammals through the saccharopine and pipecolate pathways — the former is mainly hepatic and renal, and the latter is believed to play a role in the cerebral lysine oxidation. Both pathways lead to the formation of aminoadipic semialdehyde (AASA) that is then oxidized to aminoadipate (AAA) by antiquitin (ALDH7A1). Mutations in the ALDH7A1 gene result in the accumulation of AASA and its cyclic form, piperideine-6-carboxylate (P6C), which causes pyridoxine-dependent epilepsy (PDE). P6C reacts with pyridoxal 5′-phosphate (PLP) causing its inactivation. Here, we used liquid chromatography–mass spectrometry to investigate lysine catabolism in mice injected with lysine labelled at either its nitrogen epsilon (ε-15N) or nitrogen alpha (α-15N). Analysis of ε-15N and α-15N lysine catabolites in plasma, liver and brain suggested the saccharopine as the main pathway for AAA biosynthesis. Although there was evidence for upstream cerebral pipecolate pathway activity, the resulting pipecolate does not appear to be further oxidized into AASA/P6C/AAA. By far the bulk of lysine degradation and therefore, the primary source of lysine catabolites are hepatic and renal. The results indicate that the saccharopine pathway is primarily responsible for body's production of AASA/P6C. The centrality of the saccharopine pathway in whole body lysine catabolism opens new possibilities of therapeutic targets for PDE. We suggest that inhibition of this pathway upstream of AASA/P6C synthesis may be used to prevent its accumulation benefiting PDE patients. Inhibition of the enzyme aminoadipic semialdehyde synthase, for example, could constitute a new strategy to treat PDE and other inherited diseases of lysine catabolism.
Keywords: Lysine catabolism; Saccharopine; Pipecolate; Pyridoxine dependent epilepsy; Aminoadipate semialdehyde synthase;
Securinine disturbs redox homeostasis and elicits oxidative stress-mediated apoptosis via targeting thioredoxin reductase by Junmin Zhang; Juan Yao; Shoujiao Peng; Xinming Li; Jianguo Fang (129-138).
Thioredoxin reductase (TrxR) and thioredoxin (Trx) are two major components of the thioredoxin system, which plays essential roles in regulating cellular redox signaling. Mammalian TrxRs are essential seleno-flavoenzymes with a conserved penultimate selenocysteine (Sec) residue at the C-terminus, and have attracted considerable interests as promising targets for anticancer drugs. Securinine (SCR), a major active alkaloid lactone from the Chinese herbal medicine Securinega suffruticosa, has been established clinical success in treatment of neurological disorders. Recently, increasing evidence demonstrates that SCR has potential cytotoxicity to various types of tumor cells, which enables this old central nervous system drug as a potential cancer therapeutic agent. However, the mechanism underlying the anticancer activity of SCR is not well defined. We reported here that SCR inhibits both the purified TrxR and the enzyme in intact cells. SCR elicits accumulation of reactive oxygen species (ROS), elevation of oxidized glutathione and Trx, disturbs redox homeostasis, and eventually leads to oxidative stress-mediated HeLa cell apoptosis. Importantly, pharmacological inhibition or knockdown of TrxR sensitizes the cells to SCR treatment, underpinning the physiological significance of targeting TrxR by SCR. Our discovery discloses a novel mechanism underlying the anticancer activity of SCR and provides basic data for further development of SCR as a cancer chemotherapeutic drug.Display Omitted
Keywords: Thioredoxin; Securinine; Redox homeostasis; Oxidative stress; Apoptosis; Reactive oxygen species;
Microparticles derived from obese adipose tissue elicit a pro-inflammatory phenotype of CD16+, CCR5+ and TLR8+ monocytes by Mariana Renovato-Martins; Maria Eline Matheus; Isadora Ramos de Andrade; João Alfredo Moraes; Simone Vargas da Silva; Marta Citelli dos Reis; Antônio Augusto Peixoto de Souza; César Cláudio da Silva; Eliete Bouskela; Christina Barja-Fidalgo (139-151).
Macrophage infiltration into adipose tissue (AT) is a hallmark of the chronic inflammatory response in obesity and is supported by an intense monocyte migration towards AT. Although it has been detected an increased proportion of circulating CD16+ monocyte subsets in obese subjects, the mechanisms underlying this effect and the contribution of these cells to the inflamed profile of obese AT are still poorly understood. We investigated whether factors secreted by human obese omental AT could polarize monocytes to CD16+ enriched phenotype, and how these changes could modify their migratory capacity towards adipose tissue itself. We show that explants of human obese omental AT, obtained during bariatric surgery, released higher levels of MIP1-α, TNFα, leptin and also VEGF, together with increasing amounts of microparticles (MP), when compared to explants of lean subcutaneous AT. A higher content of circulating MP derived from preadipocytes and leukocytes was also detected in plasma of obese subjects. Conditioned media or MP released from obese omental AT increased CD16 and CCR5 expression on CD14+ CD16− monocytes and augmented their migratory capacity towards the conditioned media from obese omental AT, itself. This effect was inhibited when MIP1-α was neutralized. Additionally, we demonstrate that MP derived from obese omental AT carry and transfer TLR8 to monocytes, thus triggering an increase in CD16 expression in those cells. Our data shows a positive feedback loop between blood monocytes and obese omental AT, which releases chemotactic mediators and TLR8-enriched MP, thus inducing an up-regulation of CD16+ monocytes, favoring leukocyte infiltration in the obese omental AT.
Keywords: Obesity; CD16+ monocytes; CCR5; adipose tissue; TLR8; MIP-1α;
Insights into the epigenetic mechanisms involving histone lysine methylation and demethylation in ischemia induced damage and repair has therapeutic implication by Sumana Chakravarty; Priya Jhelum; Unis Ahmad Bhat; Wenson D Rajan; Swati Maitra; Salil S Pathak; Anant B Patel; Arvind Kumar (152-164).
Cerebral ischemic stroke is one of the leading causes of death and disability worldwide. Therapeutic interventions to minimize ischemia-induced neural damage are limited due to poor understanding of molecular mechanisms mediating complex pathophysiology in stroke. Recently, epigenetic mechanisms mostly histone lysine (K) acetylation and deacetylation have been implicated in ischemic brain damage and have expanded the dimensions of potential therapeutic intervention to the systemic/local administration of histone deacetylase inhibitors. However, the role of other epigenetic mechanisms such as histone lysine methylation and demethylation in stroke-induced damage and subsequent recovery process is elusive. Here, we established an Internal Carotid Artery Occlusion (ICAO) model in CD1 mouse that resulted in mild to moderate level of ischemic damage to the striatum, as suggested by magnetic resonance imaging (MRI), TUNEL and histopathological staining along with an evaluation of neurological deficit score (NDS), grip strength and rotarod performance. The molecular investigations show dysregulation of a number of histone lysine methylases (KMTs) and few of histone lysine demethylases (KDMs) post-ICAO with significant global attenuation in the transcriptionally repressive epigenetic mark H3K9me2 in the striatum. Administration of Dimethyloxalylglycine (DMOG), an inhibitor of KDM4 or JMJD2 class of histone lysine demethylases, significantly ameliorated stroke-induced NDS by restoring perturbed H3K9me2 levels in the ischemia-affected striatum. Overall, these results highlight the novel role of epigenetic regulatory mechanisms controlling the epigenetic mark H3K9me2 in mediating the stroke-induced striatal damage and subsequent repair following mild to moderate cerebral ischemia.
Keywords: Cerebral ischemia; Magnetic resonance imaging (MRI); Inflammatory markers; Histone lysine methyl transferases (KMTs); Histone lysine demethylases (KDMs); Dimethyloxalylglycine (DMOG);
The ataxia related G1107D mutation of the plasma membrane Ca2 + ATPase isoform 3 affects its interplay with calmodulin and the autoinhibition process by Tito Calì; Martina Frizzarin; Laura Luoni; Francesco Zonta; Sergio Pantano; Carlos Cruz; Maria Cristina Bonza; Ilenia Bertipaglia; Maria Ruzzene; Maria Ida De Michelis; Nunzio Damiano; Oriano Marin; Ginevra Zanni; Giuseppe Zanotti; Marisa Brini; Raffaele Lopreiato; Ernesto Carafoli (165-173).
The plasma membrane Ca2 + ATPases (PMCA pumps) have a long, cytosolic C-terminal regulatory region where a calmodulin-binding domain (CaM-BD) is located. Under basal conditions (low Ca2 +), the C-terminal tail of the pump interacts with autoinhibitory sites proximal to the active center of the enzyme. In activating conditions (i.e., high Ca2 +), Ca2 +-bound CaM displaces the C-terminal tail from the autoinhibitory sites, restoring activity. We have recently identified a G1107D replacement within the CaM-BD of isoform 3 of the PMCA pump in a family affected by X-linked congenital cerebellar ataxia. Here, we investigate the effects of the G1107D replacement on the interplay of the mutated CaM-BD with both CaM and the pump core, by combining computational, biochemical and functional approaches. We provide evidence that the affinity of the isolated mutated CaM-BD for CaM is significantly reduced with respect to the wild type (wt) counterpart, and that the ability of CaM to activate the pump in vitro is thus decreased. Multiscale simulations support the conclusions on the detrimental effect of the mutation, indicating reduced stability of the CaM binding. We further show that the G1107D replacement impairs the autoinhibition mechanism of the PMCA3 pump as well, as the introduction of a negative charge perturbs the contacts between the CaM-BD and the pump core. Thus, the mutation affects both the ability of the pump to optimally transport Ca2 + in the activated state, and the autoinhibition mechanism in its resting state.
Keywords: Calcium signaling; Plasma membrane calcium ATPases; X-linked cerebellar ataxia; Calmodulin; Autoinhibition;
Fetuin-A downregulates adiponectin through Wnt-PPARγ pathway in lipid induced inflamed adipocyte by Soumik Agarwal; Mrittika Chattopadhyay; Sandip Mukherjee; Suman Dasgupta; Satinath Mukhopadhyay; Samir Bhattacharya (174-181).
Adiponectin secreted from adipocytes is an anti-diabetic and anti-atherogenic adipokine. Adiponectin level is known to fall significantly in obesity induced type 2 diabetes which worsen insulin sensitivity because of aberrant lipid management. However, underlying mechanism of adiponectin decrease in obese diabetic condition is yet unclear. We report here that lowering of plasma adiponectin coincided with the higher Fetuin A (FetA) level in high fat diet (HFD) induced obese diabetic mice. Knock down of FetA gene (FetAKD) elevated adiponectin level markedly in HFD mice, while reinforcement of FetA into FetAKDHFD mice reduced its level again. These results indicate FetA's involvement in the lowering of adiponectin level in obesity induced diabetic mice. Our findings to understand how FetA could affect adiponectin decrease demonstrated that FetA could enhance Wnt3a expression in the adipocyte of HFD mice. FetA addition to 3T3L1 adipocyte incubation elevated Wnt3a expression in a dose dependent manner. Overexpression of Wnt3a by FetA inhibited PPARγ and adiponectin. FetA failed to reduce PPARγ and adiponectin in Wnt3a gene knocked down 3T3L1` adipocytes. All these suggest that FetA mediate its inhibitory effect on adiponectin through Wnt3a–PPARγ pathway. Inhibition of adiponectin expression through FetA and Wnt3a significantly compromised with the activation of AMPK and its downstream signalling molecules which adversely affected lipid management causing loss of insulin sensitivity. Downregulation of adiponectin in inflamed adipocyte by FetA through the mediation of Wnt3a and PPARγ is a new report.
Keywords: Adiponectin; Fetuin-A; Wnt3a; Adipocyte; PPARγ; Insulin resistance;
Identification and characterization of the novel point mutation m.3634A>G in the mitochondrial MT-ND1 gene associated with LHON syndrome by Lidia Carreño-Gago; Josep Gamez; Yolanda Cámara; Elena Alvarez de la Campa; Juan Sebastian Aller-Alvarez; Dulce Moncho; Maria Salvado; Alicia Galan; Xavier de la Cruz; Tomàs Pinós; Elena García-Arumí (182-187).
Leber's hereditary optic neuropathy (LHON) is a mitochondrial genetic disease characterized by bilateral acute or subacute progressive central visual loss. Most cases of LHON syndrome are caused by point mutations in the MT-ND1, MT-ND4, and MT-ND6 genes.Here, we report a novel homoplasmic mutation in the MT-ND1 gene (m.3634A>G, p.Ser110Gly) in a patient with the classical clinical features of LHON syndrome.Several observations support the idea that the mutation is pathogenic and involved in the clinical phenotype of the patient: 1) The mutation affected a highly conserved amino acid, 2) A pathogenic mutation in the same amino acid (m.3635G>A, p.Ser110Asn) was previously reported in a patient with LHON syndrome, 3) The mutation is not recorded in the Mitomap or Human Mitochondrial Genome Database, 4) In silico predictors classified the mutation as “probably damaging”, and 5) Cybrids carrying the mutation showed decreased Complex I enzyme activity, lower cell proliferation, and decreased mitochondrial membrane potential relative to control cybrids.
Keywords: Novel mutation; mtDNA; MT-ND1; LHON syndrome; Cybrids;
Leucine 208 in human histamine N-methyltransferase emerges as a hotspot for protein stability rationalizing the role of the L208P variant in intellectual disability by Chanakan Tongsook; Johannes Niederhauser; Elena Kronegger; Grit Straganz; Peter Macheroux (188-199).
The degradation of histamine catalyzed by the SAM-dependent histamine N-methyltransferase (HNMT) is critically important for the maintenance of neurological processes. Recently, two mutations in the encoding human gene were reported to give rise to dysfunctional protein variants (G60D and L208P) leading to intellectual disability. In the present study, we have expressed eight L208 variants with either apolar (L208F and L208V), polar (L208N and L208T) or charged (L208D, L208H, L208K and L208R) amino acids to define the impact of side chain variations on protein structure and function. We found that the variants L208N, L208T, L208D and L208H were severely compromised in their stability. The other four variants were obtained in lower amounts in the order wild-type HNMT > L208F = L208 V > L208 K = L208R. Biochemical characterization of the two variants L208F and L208V exhibited similar Michaelis-Menten parameters for SAM and histamine while the enzymatic activity was reduced to 21% and 48%, respectively. A substantial loss of enzymatic activity and binding affinity for histamine was seen for the L208K and L208R variants. Similarly the thermal stability for the latter variants was reduced by 8 and 13 °C, respectively. These findings demonstrate that position 208 is extremely sensitive to side chain variations and even conservative replacements affect enzymatic function. Molecular dynamics simulations showed that amino acid replacements in position 208 perturb the helical character and disrupt interactions with the adjacent β-strand, which is involved in the binding and correct positioning of histamine. This finding rationalizes the gradual loss of enzymatic activity observed in the L208 variants.Display Omitted
Keywords: Isothermal titration calorimetry; Molecular dynamics simulations; Neurotransmitter; Protein stability; S-adenosylmethionine;
Triglyceride increase in the core of high-density lipoproteins augments apolipoprotein dissociation from the surface: Potential implications for treatment of apolipoprotein deposition diseases by Shobini Jayaraman; Jose Luis Sánchez-Quesada; Olga Gursky (200-210).
Lipids in the body are transported via lipoproteins that are nanoparticles comprised of lipids and amphipathic proteins termed apolipoproteins. This family of lipid surface-binding proteins is over-represented in human amyloid diseases. In particular, all major proteins of high-density lipoproteins (HDL), including apoA-I, apoA-II and serum amyloid A, can cause systemic amyloidoses in humans upon protein mutations, post-translational modifications or overproduction. Here, we begin to explore how the HDL lipid composition influences amyloid deposition by apoA-I and related proteins. First, we summarize the evidence that, in contrast to lipoproteins that are stabilized by kinetic barriers, free apolipoproteins are labile to misfolding and proteolysis. Next, we report original biochemical and biophysical studies showing that increase in triglyceride content in the core of plasma or reconstituted HDL destabilizes the lipoprotein assembly, making it more labile to various perturbations (oxidation, thermal and chemical denaturation and enzymatic hydrolysis), and promotes apoA-I release in a lipid-poor/free aggregation-prone form. Together, the results suggest that decreasing plasma levels of triglycerides will shift the dynamic equilibrium from the lipid-poor/free (labile) to the HDL-bound (protected) apolipoprotein state, thereby decreasing the generation of the protein precursor of amyloid. This prompts us to propose that triglyceride-lowering therapies may provide a promising strategy to alleviate amyloid diseases caused by the deposition of HDL proteins.Increasing triglyceride content in the core of an HDL particle augments apolipoprotein release from the HDL surface. This released protein can bind to other HDL, get degraded or get misfolded in amyloid.Display Omitted
Keywords: Cardiovascular and amyloid diseases; Protein-lipid interactions and protein misfolding; Oxidation and hydrolysis; Lipid-lowering therapies; Fibrates, statins and low-fat diets;
Search for KPNA7 cargo proteins in human cells reveals MVP and ZNF414 as novel regulators of cancer cell growth by Elisa M. Vuorinen; Nina K. Rajala; Hanna E. Rauhala; Anssi T. Nurminen; Vesa P. Hytönen; Anne Kallioniemi (211-219).
Karyopherin alpha 7 (KPNA7) belongs to a family of nuclear import proteins that recognize and bind nuclear localization signals (NLSs) in proteins to be transported to the nucleus. Previously we found that KPNA7 is overexpressed in a subset of pancreatic cancer cell lines and acts as a critical regulator of growth in these cells. This characteristic of KPNA7 is likely to be mediated by its cargo proteins that are still mainly unknown. Here, we used protein affinity chromatography in Hs700T and MIA PaCa-2 pancreatic cancer cell lines and identified 377 putative KPNA7 cargo proteins, most of which were known or predicted to localize to the nucleus. The interaction was confirmed for two of the candidates, MVP and ZNF414, using co-immunoprecipitation, and their transport to the nucleus was hindered by siRNA based KPNA7 silencing. Most importantly, silencing of MVP and ZNF414 resulted in marked reduction in Hs700T cell growth. In conclusion, these data uncover two previously unknown human KPNA7 cargo proteins with distinct roles as novel regulators of pancreatic cancer cell growth, thus deepening our understanding on the contribution of nuclear transport in cancer pathogenesis.
Keywords: KPNA7; Importin alpha 8; Nuclear transfer; Affinity chromatography; Pancreatic cancer;
The matrikine N-acetylated proline-glycine-proline induces premature senescence of nucleus pulposus cells via CXCR1-dependent ROS accumulation and DNA damage and reinforces the destructive effect of these cells on homeostasis of intervertebral discs by Chencheng Feng; Yang Zhang; Minghui Yang; Minghong Lan; Huan Liu; Jian Wang; Yue Zhou; Bo Huang (220-230).
Intervertebral disc (IVD) cell senescence is a recognized mechanism of intervertebral disc degeneration (IDD). Elucidating the molecular mechanisms underlying disc cell senescence will contribute to understanding the pathogenesis of IDD. We previously reported that N-acetylated proline-glycine-proline (N-Ac-PGP), a matrikine, is involved in the process of IDD. However, its roles in IDD are not well understood. Here, using rat nucleus pulposus (NP) cells, we found that N-Ac-PGP induced premature senescence of NP cells by binding to CXCR1. N-Ac-PGP induced DNA damage and reactive oxygen species accumulation in NP cells, which resulted in activation of the p53-p21-Rb and p16-Rb pathways. Moreover, the RT2 profiler PCR array showed that N-Ac-PGP down-regulates the expression of antioxidant genes in NP cells, suggesting a decline in the antioxidants of NP cells. On the other hand, N-Ac-PGP up-regulated the expression of matrix catabolic genes and inflammatory genes in NP cells. Concomitantly, N-Ac-PGP reinforced the destructive effects of senescent NP cells on the homeostasis of the IVDs in vivo. Our study suggests that N-Ac-PGP plays critical roles in the pathogenesis of IDD through the induction of premature senescence of disc cells and via the activation of catabolic and inflammatory cascades in disc cells. N-Ac-PGP also deteriorates the redox environment of disc cells. Hence, N-Ac-PGP is a new potential therapeutic target for IDD.
Keywords: Matrikine; N-acetylated proline-glycine-proline; Disc cell senescence; Cellular antioxidant system; Homeostasis of intervertebral disc; Intervertebral disc degeneration;
αMSH promotes preadipocyte proliferation by alleviating ER stress-induced leptin resistance and by activating Notch1 signal in mice by Lu Gan; Zhenjiang Liu; Tianjiao Wu; Fei Feng; Chao Sun (231-238).
Alpha-melanocyte stimulating hormone (αMSH) has an important role in the regulation of body weight and energy expenditure. Nevertheless, the molecular mechanisms of circulating αMSH on preadipocyte proliferation remain elusive. We found αMSH was reduced by high fat diet (HFD) while leptin was elevated in adipose tissue. Leptin resistance and endoplasmic reticulum (ER) stress of adipose tissue were increased in obese mice. αMSH increased leptin sensitivity and alleviated ER stress along with increased p-STAT3 level and reduced SOCS3, GRP78, CHOP, ATF4, p27 and p53 levels. αMSH and leptin co-treatment alleviated ER stress through decreasing the levels of GRP78 and CHOP. Tunicamycin (TM) or thapsigargin (Tg) induced ER stress blunted leptin sensitivity and inhibited preadipocyte proliferation. αMSH and leptin co-treatment increased the cell number, augmented G1-S transition, elevated leptin sensitivity, and reduced ER stress; it also activated Notch1 signal and stimulated preadipocyte proliferation, whereas ER stress marker genes were decreased during this process. However, the effects of αMSH and leptin were blocked by the specific inhibitor of Notch1 signal. In summary, our data revealed αMSH enhanced leptin sensitivity and preadipocyte proliferation, meanwhile inhibited ER stress of preadipocytes by activating Notch1 signal.Display Omitted
Keywords: αMSH; Leptin; Endoplasmic reticulum stress; Cell cycle; Notch;
CD95-mediated apoptosis in Burkitt's lymphoma B-cells is associated with Pim-1 down-regulation by Sabine Matou-Nasri; Zaki Rabhan; Haya Al-Baijan; Hamad Al-Eidi; Wesam Bin Yahya; Abdelkareem Al Abdulrahman; Nasser Almobadel; Mona Alsubeai; Saleh Al Ghamdi; Ahmed Alaskar; Mohammed AlBalwi; Mohsen Alzahrani; Ibrahim Alabdulkareem (239-252).
B-cells of the high-grade non-Hodgkin lymphoma Burkitt's lymphoma (BL) overexpress survival oncoproteins, including the proviral integration site for Moloney murine leukaemia virus kinase (Pim)-1, and become apoptosis resistant. Activated death receptor CD95 after ligation with anti-CD95 monoclonal antibody (mAb) resulted in the regression of BL via induction of apoptosis, suggesting a decrease of survival protein expression. Here, CD95-mediated apoptotic pathways in BL B-cell lines (Raji and Daudi) following treatment with anti-CD95 mAb was investigated with the cause-and-effects on pim-1 gene expression, in comparison with leukemic cell line (K562) used as CD95-negative cells. Immunohistochemical staining for CD95 and Pim-1 was performed, and the effects of anti-CD95 mAb on apoptotic signalling using western blotting, on caspase activity and cell survival of BL B-cell and leukemic cell lines were determined. We showed that Raji cells expressed more CD95 receptors than Daudi cells. Half of each population underwent apoptosis accompanied by decreased cell viability after anti-CD95 mAb treatment. Distinct extrinsic and intrinsic CD95-mediated apoptotic pathways in Raji and Daudi cells were revealed by high caspase activity and mitochondrial outer membrane permeabilization, respectively. We observed decreased Pim-1 transcript and protein expression levels with increased heat-shock protein (Hsp)70 and decreased Hsp90 expression in anti-CD95 mAb-treated cells. Throughout the study, K562 cells did not undergo apoptosis upon anti-CD95 mAb treatment. Pim-1 knockdown following to stable transfection with plasmid vectors induced apoptosis and decreased viability of BL and K562 cells. Therefore, CD95-mediated apoptosis induces Pim-1 down-regulation in BL B-cells, but Pim-1 down-regulation cannot fully eradicate BL and leukaemia.
Keywords: Burkitt; Apoptosis; CD95; Pim-1; Raji; Daudi;
SOX2 function and Hedgehog signaling pathway are co-conspirators in promoting androgen independent prostate cancer by Swayamsiddha Kar; Dipta Sengupta; Moonmoon Deb; Nibedita Pradhan; Samir Kumar Patra (253-265).
Developmentally inclined hedgehog (HH) signaling pathway and pluripotency inducing transcription factor SOX2 have been known to work syngerstically during cellular reprogramming events to facilitate efficient differentiation. Hence, it is not surprising that both the factors are actively involved in arbitrating malignant growth, including prostate cancer progression. Here, we have described in details the potential mechanisms by which SOX2 effects neoplastic characteristics in prostate cancer and investigated the consequences of simultaneous down-regulation of SOX2 and HH pathway in androgen-independent human prostate cancer cells. Expression of SOX2 has been determined by qRT-PCR, western blot, immunohistochemistry and immunocytochemistry analyses; its functional role determined by gene knockdown using RNAi and over-expression via chemical activation in HaCaT, DU145 and PC-3 cells. Changes in level of cell proliferation, migration and apoptosis profiles were measured by MTT, FACS, chromatin condensation and scratch assays respectively. SOX2 was expressed in all the three cell lines and its inhibition reduced cell proliferation and induced apoptosis. Most importantly, when both SOX2 and HH pathway were targeted simultaneously, cell proliferation was greatly reduced, apoptotic cell population increased drastically and migration potential was reduced. Moreover, gene expression of EMT markers such as E-cadherin and apoptosis related Bcl-2 and Bax was also investigated wherein decrease in E-cadherin and Bcl-2 levels and increase in Bax expression further substantiating our claim. These findings could provide the basis for a novel therapeutic strategy targeting both the effector i.e. SOX2 and perpetuator i.e. HH pathway of aggressive tumorigenic properties in androgen independent prostate cancer.
Keywords: Cell signaling; Transcription factor; Prostate cancer; Gene silencing; HH signaling; SOX2;
Cognitive decline in type 2 diabetic db/db mice may be associated with brain region-specific metabolic disorders by Hong Zheng; Yongquan Zheng; Liangcai Zhao; Minjiang Chen; Guanghui Bai; Yongsheng Hu; Wenyi Hu; Zhihan Yan; Hongchang Gao (266-273).
Type 2 diabetes has been associated with cognitive decline, but its metabolic mechanism remains unclear. In the present study, we attempted to investigate brain region-specific metabolic changes in db/db mice with cognitive decline and explore the potential metabolic mechanism linking type 2 diabetes and cognitive decline. We analyzed the metabolic changes in seven brain regions of two types of mice (wild-type mice and db/db mice with cognitive decline) using a 1H NMR-based metabolomic approach. Then, a mixed-model analysis was used to evaluate the effects of mice type, brain region, and their interaction on metabolic changes. Compared with the wild-type mice, the db/db mice with cognitive decline had significant increases in lactate, glutamine (Gln) and taurine as well as significant decreases in alanine, aspartate, choline, succinate, γ-Aminobutyric acid (GABA), glutamate (Glu), glycine, N-acetylaspartate, inosine monophosphate, adenosine monophosphate, adenosine diphosphate, and nicotinamide adenine dinucleotide. Brain region-specific metabolic differences were also observed between these two mouse types. In addition, we found significant interaction effects of mice type and brain region on creatine/phosphocreatine, lactate, aspartate, GABA, N-acetylaspartate and taurine. Based on metabolic pathway analysis, the present study suggests that cognitive decline in db/db mice might be linked to a series of brain region-specific metabolic changes, involving an increase in anaerobic glycolysis, a decrease in tricarboxylic acid (TCA) and Gln-Glu/GABA cycles as well as a disturbance in lactate-alanine shuttle and membrane metabolism.
Keywords: Brain; Cognition; Diabetes; Metabolomics; Region-specific; Mixed model;
Altered expression of glial markers, chemokines, and opioid receptors in the spinal cord of type 2 diabetic monkeys by Norikazu Kiguchi; Huiping Ding; Christopher M. Peters; Nancy D. Kock; Shiroh Kishioka; J. Mark Cline; Janice D. Wagner; Mei-Chuan Ko (274-283).
Neuroinflammation is a pathological condition that underlies diabetes and affects sensory processing. Given the high prevalence of pain in diabetic patients and crosstalk between chemokines and opioids, it is pivotal to know whether neuroinflammation-associated mediators are dysregulated in the central nervous system of diabetic primates. Therefore, the aim of this study was to investigate whether mRNA expression levels of glial markers, chemokines, and opioid receptors are altered in the spinal cord and thalamus of naturally occurring type 2 diabetic monkeys (n = 7) compared with age-matched non-diabetic monkeys (n = 6). By using RT-qPCR, we found that mRNA expression levels of both GFAP and IBA1 were up-regulated in the spinal dorsal horn (SDH) of diabetic monkeys compared with non-diabetic monkeys. Among all chemokines, expression levels of three chemokine ligand-receptor systems, i.e., CCL2-CCR2, CCL3-CCR1/5, and CCL4-CCR5, were up-regulated in the SDH of diabetic monkeys. Moreover, in the SDH, seven additional chemokine receptors, i.e., CCR4, CCR6, CCR8, CCR10, CXCR3, CXCR5, and CXCR6, were also up-regulated in diabetic monkeys. In contrast, expression levels of MOP, KOP, and DOP, but not NOP receptors, were down-regulated in the SDH of diabetic monkeys, and the thalamus had fewer changes in the glial markers, chemokines and opioids. These findings indicate that neuroinflammation, manifested as glial activation and simultaneous up-regulation of multiple chemokine ligands and receptors, seems to be permanent in type 2 diabetic monkeys. As chemokines and opioids are important pain modulators, this first-in-primate study provides a translational bridge for determining the functional efficacy of spinal drugs targeting their signaling cascades.
Keywords: Astrocytes; Microglia; Chemokines; Opioids; Neuroinflammation; Chronic pain; Spinal cord; Thalamus; Diabetes; Macaques;
The addition of ketone bodies alleviates mitochondrial dysfunction by restoring complex I assembly in a MELAS cellular model by Samuel Frey; Guillaume Geffroy; Valerie Desquiret-Dumas; Naig Gueguen; Celine Bris; Sophie Belal; Patrizia Amati-Bonneau; Arnaud Chevrollier; Magalie Barth; Daniel Henrion; Guy Lenaers; Dominique Bonneau; Pascal Reynier; Vincent Procaccio (284-291).
Ketogenic Diet used to treat refractory epilepsy for almost a century may represent a treatment option for mitochondrial disorders for which effective treatments are still lacking. Mitochondrial complex I deficiencies are involved in a broad spectrum of inherited diseases including Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes syndrome leading to recurrent cerebral insults resembling strokes and associated with a severe complex I deficiency caused by mitochondrial DNA (mtDNA) mutations.The analysis of MELAS neuronal cybrid cells carrying the almost homoplasmic m.3243A > G mutation revealed a metabolic switch towards glycolysis with the production of lactic acid, severe defects in respiratory chain activity and complex I disassembly with an accumulation of assembly intermediates. Metabolites, NADH/NAD+ ratio, mitochondrial enzyme activities, oxygen consumption and BN-PAGE analysis were evaluated in mutant compared to control cells. A severe complex I enzymatic deficiency was identified associated with a major complex I disassembly with an accumulation of assembly intermediates of 400 kDa. We showed that Ketone Bodies (KB) exposure for 4 weeks associated with glucose deprivation significantly restored complex I stability and activity, increased ATP synthesis and reduced the NADH/NAD + ratio, a key component of mitochondrial metabolism. In addition, without changing the mutant load, mtDNA copy number was significantly increased with KB, indicating that the absolute amount of wild type mtDNA copy number was higher in treated mutant cells. Therefore KB may constitute an alternative and promising therapy for MELAS syndrome, and could be beneficial for other mitochondrial diseases caused by complex I deficiency.
Keywords: Mitochondria; Mitochondrial diseases; Mitochondrial DNA; MELAS syndrome; Complex I assembly; Ketone bodies;
Functional significance of exosomes applied in sepsis: A novel approach to therapy by Jingjing Wu; Yini Wang; Lanjuan Li (292-297).
The nanoparticles referred as exosomes play an active role in intercellular communication. Their potential positive therapeutic effect in bacterial inflammation and sepsis has been the subject of several studies that have examined the feasibility of exosomes as drug-delivery vehicles. The underlying mechanism of interest involves the selective transport of cellular cargo. Most attention has been focused on the exosome-mediated transport of microRNA and protein. Thus, exosomes are expected to be an important tool in the treatment of inflammatory disease. This review covers the relevant literature, focusing on the relationship between exosomes and sepsis and therapeutic use of exosomes in bacterially mediated inflammation or sepsis. We evaluate exosomes as drug vehicles, including their therapeutic cargo, potential mechanisms of action, choice of donor cells, and routes of administration.
Keywords: Exosome; Sepsis; Drug vehicle; Biomarker; miRNA;
The role of α-smooth muscle actin in fibroblast-mediated matrix contraction and remodeling by Arti V. Shinde; Claudio Humeres; Nikolaos G. Frangogiannis (298-309).
Cardiac myofibroblasts play an important role in myocardial remodeling. Although α-smooth muscle actin (α-SMA) expression is the hallmark of mature myofibroblasts, its role in regulating fibroblast function remains poorly understood. We explore the effects of the matrix environment in modulating cardiac fibroblast phenotype, and we investigate the role of α-SMA in fibroblast function using loss- and gain-of-function approaches. In murine myocardial infarction, infiltration of the infarct border zone with abundant α-SMA-positive myofibroblasts was associated with scar contraction. Isolated cardiac fibroblasts cultured in plates showed high α-SMA expression localized in stress fibers, exhibited activation of focal adhesion kinase (FAK), and synthesized large amounts of extracellular matrix proteins. In contrast, when these cells were cultured in collagen lattices, they exhibited marked reduction of α-SMA expression, negligible FAK activation, attenuated collagen synthesis, and increased transcription of genes associated with matrix metabolism. Transforming Growth Factor-β1-mediated contraction of fibroblast-populated collagen pads was associated with accentuated α-SMA synthesis. In contrast, serum- and basic Fibroblast Growth Factor-induced collagen pad contraction was associated with reduced α-SMA expression. α-SMA siRNA knockdown attenuated contraction of collagen pads populated with serum-stimulated cells. Surprisingly, α-SMA overexpression also reduced collagen pad contraction, suggesting that α-SMA is not sufficient to promote contraction of the matrix. Reduced contraction by α-SMA-overexpressing cells was associated with attenuated proliferative activity, in the absence of any effects on apoptosis. α-SMA may be implicated in contraction and remodeling of the extracellular matrix, but is not sufficient to induce contraction. α-SMA expression may modulate cellular functions, beyond its effects on contractility.
Keywords: Myofibroblast; α-Smooth muscle actin; Myocardial infarction; Extracellular matrix; Transforming growth factor-β;
Challenging drug target for Parkinson's disease: Pathological complex of the chameleon TPPP/p25 and alpha-synuclein proteins by Tibor Szénási; Judit Oláh; Adél Szabó; Sándor Szunyogh; András Láng; András Perczel; Attila Lehotzky; Vladimir N. Uversky; Judit Ovádi (310-323).
The hallmarks of Parkinson's disease and other synucleinopathies, Tubulin Polymerization Promoting Protein (TPPP/p25) and α-synuclein (SYN) have two key features: they are disordered and co-enriched/co-localized in brain inclusions. These Neomorphic Moonlighting Proteins display both physiological and pathological functions due to their interactions with distinct partners. To achieve the selective targeting of the pathological TPPP/p25-SYN but not the physiological TPPP/p25-tubulin complex, their interfaces were identified as a specific innovative strategy for the development of anti-Parkinson drugs. Therefore, the interactions of TPPP/p25 with tubulin and SYN were characterized which suggested the involvements of the 178–187 aa and 147–156 aa segments in the complexation of TPPP/p25 with tubulin and SYN, respectively. However, various truncated and deletion mutants reduced but did not abolish the interactions except one mutant; in addition synthetized fragments corresponding to the potential binding segments of TPPP/p25 failed to interact with SYN. In fact, the studies of the multiple interactions at molecular and cellular levels revealed the high conformational plasticity, chameleon feature, of TPPP/p25 that ensures exceptional functional resilience; the lack of previously identified binding segments could be replaced by other segments. The experimental results are underlined by distinct bioinformatics tools. All these data revealed that although targeting chameleon proteins is a challenging task, nevertheless, the validation of a drug target can be achieved by identifying the interface of complexes of the partner proteins existing at the given pathological conditions.
Keywords: Tubulin Polymerization Promoting Protein/p25; α-Synuclein; Deletion mutants; Protein chameleon; Drug target; Bimolecular fluorescence complementation;
Re-expression of cell cycle markers in aged neurons and muscles: Whether cells should divide or die? by Renu Sharma; Dhiraj Kumar; Niraj Kumar Jha; Saurabh Kumar Jha; Rashmi K Ambasta; Pravir Kumar (324-336).
Emerging evidence revealed that abrogated cell cycle entry into highly differentiated mature neurons and muscles is having detrimental consequences in response to cell cycle checkpoints disruption, altered signaling cascades, pathophysiological and external stimuli, for instance, Aβ, Parkin, p-tau, α-synuclein, impairment in TRK, Akt/GSK3β, MAPK/Hsp90, and oxidative stress. These factors, reinitiate undesired cell division by triggering new DNA synthesis, replication, and thus exquisitely forced mature cell to enter into a disturbed and vulnerable state that often leads to death as reported in many neuro- and myodegenerative disorders. A pertinent question arises how to reverse this unwanted pathophysiological phenomenon is attributed to the usage of cell cycle inhibitors to prevent the degradation of crucial cell cycle arresting proteins, cyclin inhibitors, chaperones and E3 ligases. Herein, we identified the major culprits behind the forceful cell cycle re-entry, elucidated the cyclin re-expression based on disturbed signaling mechanisms in neuromuscular degeneration together with plausible therapeutic strategies.Display Omitted
Keywords: Post-mitotic cell division; Signaling cascade; Neuromuscular degeneration; Cyclins; Therapeutics;
microRNAs in the pathophysiology of CKD-MBD: Biomarkers and innovative drugs by Valérie Metzinger-Le Meuth; Stéphane Burtey; Pierre Maitrias; Ziad A. Massy; Laurent Metzinger (337-345).
microRNAs comprise a novel class of endogenous small non-coding RNAs that have been shown to be implicated in both vascular damage and bone pathophysiology. Chronic kidney disease-mineral bone disorder (CKD-MBD) is characterized by vessel and bone damage secondary to progressive loss of kidney function. In this review, we will describe how several microRNAs have been implicated, in recent years, in cellular and animal models of CKD-MBD, and have been very recently shown to be deregulated in patients with CKD. Particular emphasis has been placed on the endothelial-specific miR-126, a potential biomarker of endothelial dysfunction, and miR-155 and miR-223, which play a role in both vascular smooth muscle cells and osteoclasts, with an impact on the vascular calcification and osteoporosis process. Finally, as these microRNAs may constitute useful targets to prevent or treat complications of CKD-MBD, we will discuss their potential as innovative drugs, describe how they could be delivered in a timely and specific way to vessels and bone by using the most recent techniques such as nanotechnology, viral vectors or CRISPR gene targeting.
Keywords: microRNA; Bone; Vascular disease; CKD; Gene therapy; Biomarker;