BBA - Molecular Basis of Disease (v.1782, #9)

Notch signaling and diseases: An evolutionary journey from a simple beginning to complex outcomes by Claudio Talora; Antonio F. Campese; Diana Bellavia; Maria Pia Felli; Alessandra Vacca; Alberto Gulino; Isabella Screpanti (489-497).
Notch signaling pathway regulates a wide variety of cellular processes during development and it also plays a crucial role in human diseases. This important link is firmly established in cancer, since a rare T-ALL-associated genetic lesion has been initially reported to result in deletion of Notch1 ectodomain and constitutive activation of its intracellular region. Interestingly, the cellular response to Notch signaling can be extremely variable depending on the cell type and activation context. Notch signaling triggers signals implicated in promoting carcinogenesis and autoimmune diseases, whereas it can also sustain responses that are critical to suppress carcinogenesis and to negatively regulate immune response. However, Notch signaling induces all these effects via an apparently simple signal transduction pathway, diversified into a complex network along evolution from Drosophila to mammals. Indeed, an explanation of this paradox comes from a number of evidences accumulated during the last few years, which dissected the intrinsic canonical and non-canonical components of the Notch pathway as well as several modulatory extrinsic signaling events. The identification of these signals has shed light onto the mechanisms whereby Notch and other pathways collaborate to induce a particular cellular phenotype. In this article, we review the role of Notch signaling in cells as diverse as T lymphocytes and epithelial cells of the epidermis, with the main focus on understanding the mechanisms of Notch versatility.
Keywords: Notch signaling; Autoimmunity; Lymphomagenesis; Skin cancer;

The emerging potential of α-tocopheryl phosphate, a phosphoric acid ester of α-tocopherol, in health benefits was tested gavaging this compound (5 mg/kg body wt) to a group of rats for a period of thirty days while the control rats were given water only. After thirty days, the rats were sacrificed, the hearts excised, and the isolated hearts were perfused by working mode. Both control and experimental hearts were subjected to 30-min global ischemia followed by 2 h of reperfusion. The tocopheryl phosphate fed rats exhibited significant cardioprotection as evidenced by improved ventricular performance and reduced myocardial infarct size and cardiomyocyte apoptosis. Supplementation with α-tocopheryl phosphate converted MAP kinase-induced death signal into a survival signal by enhancing anti-apoptotic p42/44 ERK kinase and p38 MAPKβ and reducing pro-apoptotic proteins p38 MAPKα and JNK. In concert, the phosphorylation of pro-apoptotic c-Src was also reduced. Tocopheryl phosphate increased the DNA binding of the redox-sensitive transcription factor NFκB and potentiated the activation of anti-death protein Bcl-2 and survival signaling protein Akt. The results of this study demonstrated for the first time that tocopheryl phosphate could ameliorate myocardial ischemic reperfusion injury by converting ischemia/reperfusion-mediated death signal into a survival signal by modulating MAP kinase signaling.
Keywords: Tocopheryl phosphate; Cardioprotection; α-Tocotrienol; Ischemia reperfusion injury; c-Src; Akt; MAP kinase;

Inhibition of erythroblast growth and fetal hemoglobin production by ribofuranose-substituted adenosine derivatives by Natarajan V. Bhanu; Y. Terry Lee; Patricia A. Oneal; Nicole M. Gantt; Wulin Aerbajinai; Pierre Noel; Craig J. Thomas; Jeffery L. Miller (504-510).
In vivo, inhibition of fetal hemoglobin (HbF) expression in humans around the time of birth causes the clinical manifestation of sickle cell and beta-thalassemia syndromes. Inhibition of HbF among cultured cells was recently described by the adenosine derivative molecule named SQ22536. Here, a primary cell culture model was utilized to further explore the inhibition of HbF by adenosine derivative molecules. SQ22536 demonstrated down-regulation of growth and HbF expression among erythroblasts cultured from fetal and adult human blood. The effects upon HbF were noted in a majority of cells, and quantitative PCR analysis demonstrated a transcriptional mechanism. Screening assays demonstrated that two additional molecules named 5′-deoxy adenosine and 2′,3′-dideoxy adenosine had effects on HbF comparable to SQ22536. Other adenosine derivative molecules, adenosine receptor binding ligands, and cAMP-signaling regulators failed to inhibit HbF in matched cultures. These results suggest that structurally related ribofuranose-substituted adenosine analogues act through an unknown mechanism to inhibit HbF expression in fetal and adult human erythroblasts.
Keywords: Human erythropoiesis; Cytokine; HbF inhibition; Adenosine derivative; SQ22536; Hemoglobinopathy;

Insulin potentiates cytokine-induced VCAM-1 expression in human endothelial cells by Rosalinda Madonna; Marika Massaro; Raffaele De Caterina (511-516).
Hyperinsulinemia is an independent risk factor for cardiovascular events and may contribute to cardiovascular disease. Low-grade chronic inflammation has been implicated in the pathogenesis of atherosclerosis. We aimed at determining the impact of pathophysiologically high insulin concentrations on cytokine-induced endothelial activation in human umbilical vein endothelial cells (HUVEC). HUVEC were incubated with insulin (0–24 h) ± tumor necrosis factor (TNF)-α or lipopolysaccharide (LPS). At pathophysiological/pharmacological concentrations (10− 9–10− 7 mol/L), insulin selectively induced VCAM-1 expression and potentiated the effects of TNF-α and LPS, effects reverted by the proteasome inhibitor lactacystin. Compared with TNF-α alone, insulin + TNF-α doubled U937 cell adhesion. Insulin markedly increased TNF-α-induced NF-κB activation and induced phosphorylated IκB-α accumulation. Therefore, hyperinsulinemia enhances cytokine-induced VCAM-1 expression in endothelial cells, thus potentially contributing to detrimental effects of other inflammatory stimuli on atherogenesis.
Keywords: Insulin; Atherosclerosis; Vascular cell adhesion molecule-1; Cytokine; Type 2 diabetes; Insulin resistance;

Anti-apoptotic treatment reduces transthyretin deposition in a transgenic mouse model of Familial Amyloidotic Polyneuropathy by Bárbara Macedo; Ana Rita Batista; Nelson Ferreira; Maria Rosário Almeida; Maria João Saraiva (517-522).
Tauroursodeoxycholic acid (TUDCA) is a unique natural compound that acts as a potent anti-apoptotic and anti-oxidant agent, reducing cytotoxicity in several neurodegenerative diseases. Since oxidative stress, apoptosis and inflammation are associated with transthyretin (TTR) deposition in Familial Amyloidotic Polyneuropathy (FAP), we investigated the possible TUDCA therapeutical application in this disease. We show by semi-quantitative immunohistochemistry and western blotting that administration of TUDCA to a transgenic mouse model of FAP decreased apoptotic and oxidative biomarkers usually associated with TTR deposition, namely the ER stress markers BiP and eIF2α, the Fas death receptor and oxidation products such as 3-nitrotyrosine. Most important, TUDCA treatment significantly reduced TTR toxic aggregates in as much as 75%. Since TUDCA has no effect on TTR aggregation “in vitro”, this finding points for the “in vivo” modulation of TTR aggregation by cellular responses, such as by oxidative stress, ER stress and apoptosis and prompts for the use of this safe drug in prophylactic and therapeutic measures in FAP.
Keywords: Tauroursodeoxycholic acid (TUDCA); Amyloid; Protein aggregation; Cytotoxicity; Apoptosis; ER stress;

Oligomer-specific Aβ toxicity in cell models is mediated by selective uptake by Sidhartha M. Chafekar; Frank Baas; Wiep Scheper (523-531).
Alzheimer's disease (AD) is characterized by the aggregation and subsequent deposition of misfolded β-amyloid (Aβ) peptide. Previous studies show that aggregated Aβ is more toxic in oligomeric than in fibrillar form, and that each aggregation form activates specific molecular pathways in the cell. We hypothesize that these differences between oligomers and fibrils are related to their different accessibility to the intracellular space. To this end we used fluorescently labelled Aβ1–42 and demonstrate that Aβ1–42 oligomers readily enter both HeLa and differentiated SK‑N‑SH cells whereas fibrillar Aβ1–42 is not internalized. Oligomeric Aβ1–42 is internalized by an endocytic process and is transported to the lysosomes. Inhibition of uptake specifically inhibits oligomer but not fibril toxicity. Our study indicates that selective uptake of oligomers is a determinant of oligomer specific Aβ toxicity.
Keywords: Alzheimer's disease; β-amyloid; Aggregation; Oligomer; Toxicity; Uptake;

Influence of increased adiposity on mitochondrial-associated proteins of the rat colon: A proteomic and transcriptomic analysis by Sara Padidar; Andrew J. Farquharson; Garry J. Rucklidge; Janice E. Drew (532-541).
Epidemiological studies report obesity to be an important risk factor influencing colon pathologies, yet mechanism(s) are unknown. Recent studies have shown significant elevation of insulin, leptin and triglycerides associated with increased adipose tissue. In situ hybridisation studies have located insulin, leptin and adiponectin receptor expression in the colon epithelia. The influence of increased adiposity and associated deregulation of insulin and adipokines on regulation of the colon epithelium is unknown. Altered adipokine and insulin signalling associated with obesity has an impact on mitochondrial function and mitochondrial dysfunction is increasingly recognised as a contributing factor in many diseases. Proteomics and transcriptomics are potentially powerful methods useful in elucidating the mechanisms whereby obesity increases risk of colon diseases as observed epidemiologically. This study investigated colon mitochondrial-associated protein profiles and corresponding gene expression in colon in response to increased adiposity in a rat model of diet induced obesity. Increased adiposity in diet-induced obese sensitive rats was found to be associated with altered protein expression of 69 mitochondrial-associated proteins involved in processes associated with calcium binding, protein folding, energy metabolism, electron transport chain, structural proteins, protein synthesis and degradation, redox regulation, and transport. The changes in these mitochondrial protein profiles were not correlated with changes at the gene expression level assessed using real-time PCR arrays.
Keywords: 2DPAGE; DIOS; DIOR; ETC; GAPDH; LC/MS/MS; MPEFs; Real-time PCR array; Mitochondrial dysfunction; Obesity; Colon;

Attenuated response to liver injury in moesin-deficient mice: Impaired stellate cell migration and decreased fibrosis by Tokunari Okayama; Shojiro Kikuchi; Toshiya Ochiai; Hisashi Ikoma; Takeshi Kubota; Daisuke Ichikawa; Hitoshi Fujiwara; Kazuma Okamoto; Chouhei Sakakura; Teruhisa Sonoyama; Yukihito Kokuba; Yoshinori Doi; Sachiko Tsukita; D. Montgomery Bissell; Eigo Otsuji (542-548).
Hepatic stellate cells (HSCs) respond to injury with a coordinated set of events (termed activation), which includes migration and upregulation of matrix protein production. Cell migration requires an intact actin cytoskeleton that is linked to the plasma membrane by ezrin–radixin–moesin (ERM) proteins. We have previously found that the linker protein in HSCs is exclusively moesin. Here, we describe HSC migration and fibrogenesis in moesin-deficient mice. We developed an acute liver injury model that involved focal thermal denaturation and common bile duct ligation. HSC migration and collagen deposition were assessed by immunohistology and quantitative real-time PCR. Activated HSCs were isolated from wild-type or moesin-deficient mice for direct examination of migration. Activated HSCs from wild-type mice were positive for moesin. Migration of moesin-deficient HSCs was significantly reduced. In a culture assay, 22.1% of normal HSCs migrated across a filter in 36h. In contrast, only 1.3% of activated moesin-deficient HSCs migrated. Collagen deposition around the injury area similarly was reduced in moesin-deficient liver. The linker protein moesin is essential for HSC activation and migration in response to injury. Fibrogenesis is coupled to migration and reduced in moesin-deficient mice. Agents that target moesin may be beneficial for chronic progressive fibrosis.
Keywords: ERM; Thermal denaturation; Wound healing; Anti-fibrotic; Collagen synthesis;