Increased hexosamine biosynthetic pathway flux alters cell-cell adhesion in INS-1E cells and murine islets

Purpose In type 2 Diabetes, beta-cell failure is caused by loss of cell mass, mostly by apoptosis, but also by simple dysfunction (dedifferentiation, decline of glucose-stimulated insulin secretion). Apoptosis and dysfunction are caused, at least in part, by glucotoxicity, in which increased flux of glucose in the hexosamine biosynthetic pathway plays a role. In this study, we sought to clarify whether increased hexosamine biosynthetic pathway flux affects another important aspect of beta-cell physiology, that is beta-cell-beta-cell homotypic interactions. Methods We used INS-1E cells and murine islets. The expression and cellular distribution of E-cadherin and beta-catenin was evaluated by immunofluorescence, immunohistochemistry and western blot. Cell-cell adhesion was examined by the hanging-drop aggregation assay, islet architecture by isolation and microscopic observation. Results E-cadherin expression was not changed by increased hexosamine biosynthetic pathway flux, however, there was a decrease of cell surface, and an increase in intracellular E-cadherin. Moreover, intracellular E-cadherin delocalized, at least in part, from the Golgi complex to the endoplasmic reticulum. Beta-catenin was found to parallel the E-cadherin redistribution, showing a dislocation from the plasmamembrane to the cytosol. These changes had as a phenotypic consequence a decreased ability of INS-1E to aggregate. Finally, in ex vivo experiments, glucosamine was able to alter islet structure and to decrease surface abundandance of E-cadherin and beta-catenin. Conclusion Increased hexosamine biosynthetic pathway flux alters E-cadherin cellular localization both in INS-1E cells and murine islets and affects cell-cell adhesion and islet morphology. These changes are likely caused by alterations of E-cadherin function, highlighting a new potential target to counteract the consequences of glucotoxicity on beta-cells

Saponins from Tribulus Terrestris L. protect human keratinocytes from UVB-induced damage

Chronic exposure to solar UVB radiation damages skin, increasing the risk to develop cancer. Hence the identification of compounds with a photoprotective efficacy is essential. This study examined the role of saponins derived from Tribulus terrestris L. (TT) on the modulation of apoptosis in normal human keratinocytes (NHEK) exposed to physiological doses of UVB and to evaluate their antitumoral properties. In NHEK, TT saponins attenuate UVB-induced programmed cell death through inhibition of intrinsic apoptotic pathway. In squamous cell carcinomas (SCC) TT saponins do not make the malignant keratinocytes more resistant to UVB and determine an enhanced apoptotic response. The photoprotective effect of TT saponins is tightly correlated to the enhancement of NER genes expression and the block of UVB-mediated NF-κB activation. Collectively, our study shows experimental evidence that TT has a preventive efficacy against UVB-induced carcinogenesis and the molecular knowledge on the mechanisms through which TT saponins regulate cell death suggests great potential for TT to be developed into a new medicine for cancer patients

Selective cyclooxygenase-1 inhibition by p6 and gastrotoxicity: preliminary investigation

Gastrointestinal damage (GD) is commonly associated with the inhibition of cyclooxygenase (COX)-1, one of the two known COXs, by traditional non-steroidal anti-inflammatory drugs. More recent evidences have proven that GD is caused by the simultaneous inhibition of the two COXs. This study was designed to evaluate the effect of the selective COX-1 inhibition on gastric integrity

Radio Electric Asymmetric Conveyer Technology Modulates Neuroinflammation in a Mouse Model of Neurodegeneration

In this study, the effects of Radio Electric Asymmetric Conveyer (REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), were investigated in vivo. We found that the REAC tissue optimization treatment specific for neuro-regenerative purposes (REAC TO-RGN-N) attenuated the inflammatory picture evoked by MPTP-induced nigro-striatal damage in mice, decreasing the levels of pro-inflammatory molecules and increasing anti-inflammatory mediators. Besides, there was a significant reduction of both astrocyte and microglial activation in MPTP-treated mice exposed to REAC TO-RGN-N. These results indicated that REAC TO-RGN-N treatment modulates the pro-inflammatory responses and reduces neuronal damage in MPTP-induced parkinsonism

Proteomic expression profile of injured rat peripheral nerves revealed biological networks and processes associated with nerve regeneration

International audiencePeripheral nerve regeneration is regulated through the coordinated spatio-temporal activation of multiple cellular pathways. In this work, an integrated proteomics and bioinformatics approach was employed to identify differentially expressed proteins at the injury-site of rat sciatic nerve at 20 days after damage. By a label-free liquid chromatography mass-spectrometry (LC-MS/MS) approach, we identified 201 differentially proteins that were assigned to specific canonical and disease and function pathways. These include proteins involved in cytoskeleton signaling and remodeling, acute phase response, and cellular metabolism. Metabolic proteins were significantly modulated after nerve injury to support a specific metabolic demand. In particular, we identified a group of proteins involved in lipid uptake and lipid storage metabolism. Immunofluorescent staining for acyl-CoA diacylglycerol acyltransferase 1 (DGAT1) and DAGT2 expression provided evidence for the expression and localization of these two isoforms in Schwann cells at the injury site in the sciatic nerve. This further supports a specific local regulation of lipid metabolism in peripheral nerve after damage