Sterol regulatory element-binding protein-1c knockdown protected INS-1E cells from lipotoxicity

OBJECTIVE

The reduction in insulin secretory capacity and beta-cell mass has been attributed, at least partially, to lipotoxicity, which may contribute to the development of type 2 diabetes. Chronic free fatty acids (FFA) exposure impairs pancreatic beta-cell function and induces beta-cell apoptosis. This study is to elucidate the underlying molecular mechanisms.

RESEARCH DESIGN AND METHODS

We exposed INS-1E pancreatic beta-cell line to palmitate or oleate, and measured the glucose stimulated insulin secretion (GSIS). The effect of FFA on sterol regulatory element-binding protein (SREBP)-1c lipogenic pathway, and expression of genes involved in beta-cell functions, including AMPK (AMP-activated protein kinase), UCP-2 (uncoupling protein-2), IRS-2 (insulin receptor substrate-2), PDX-1 (pancreatic duodenal homeobox-1), GLUT-2 (glucose transporter-2) and B cell lymphoma/leukaemia-2 (Bcl-2) were investigated. Apoptosis of these exposed cells was determined by MitoCapture, Annexin V-Cy3 or terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. Cell lipid accumulation was measured by oil red O staining or TG extraction. Also SREBP-1c expression knockdown were used.

RESULTS

FFA treatment resulted in SREBP-1c overexpression, impaired GSIS, lipid accumulation, apoptosis of INS-1E cells. In addition, the expression of lipogenic genes and UCP-2 were upregulated, but AMPK, IRS-2, PDX-1, GLUT-2 and Bcl-2 were downregulated in the exposed cells. However, these lipotoxic effects of FFA were largely prevented by induction of a SREBP-1c small interfering RNA.

CONCLUSIONS

These data suggest a strong correlation between FFA treatment and SREBP-1c activation in INS-1E cells. SREBP-1c might be a major factor responsible for beta-cell lipotoxicity, and SREBP-1c knockdown could protect INS-1E cells from lipotoxicity, which is implicating a therapeutic potential for treating diabetes related to lipotoxicity.

Epigallocatechin-3-O-gallate (EGCG) protects the insulin sensitivity in rat L6 muscle cells exposed to dexamethasone condition

The tea polyphenol epigallocatechin-3-O-gallate (EGCG) displays some antidiabetic effects; however the mechanisms are incompletely understood. In the present study, the investigation of the effects of EGCG on insulin resistance was performed in rat L6 cells treated with dexamethasone. We found that dexamethasone increased Ser307 phosphorylation of insulin receptor substrate-1 (IRS-1) and reduced phosphorylation of AMPK and Akt. Furthermore, glucose uptake and glucose transporter (GLUT4) translocation were inhibited by dexamethasone. However, the treatment of EGCG improved insulin-stimulated glucose uptake by increasing GLUT4 translocation to plasma membrane. Furthermore, we also demonstrated these EGCG effects essentially depended on the AMPK and Akt activation. Together, our data suggested that EGCG inhibited dexamethasone-induced insulin resistance through AMPK and PI3K/Akt pathway.

Gender differences in health among the Japanese elderly

Evidence has emerged recently to challenge the widely held notion that women experience more physical health problems than men. The purpose of this study is to re-evaluate this issue with a broad range of health measures gathered in a culturally diverse population--older adults in Japan. Taken as a whole, the findings suggest that there are gender differences in health. However, patterns of female excess in morbidity depend upon the type of health status measure that is examined. In particular, the data reveal that elderly women experience more functional disability and rate their overall health less favorably than older men. In contrast, a consistent pattern of gender differences in health fail to emerge when specific acute and chronic health problems are evaluated.

Myeloperoxidase (MPO) and interleukin-17 (IL-17) plasma levels are increased in patients with acute coronary syndromes

There are several reports of myeloperoxidase (MPO) playing an important role in acute coronary syndromes (ACS). Interleukin-17 (IL-17) is a pro-inflammatory cytokine produced by activated CD4 T cells that has a chemotactic and activating effect on neutrophils. It has also been shown that IL-17 recruits neutrophils via the release of C-X-C chemokines. The roles of MPO and IL-17 in ACS, however, have not been established. This study measured plasma MPO and IL-17 levels in 10 patients with ACS, 11 age- and sex-matched patients with stable angina and 12 healthy control subjects. Plasma MPO and IL-17 levels were significantly elevated in ACS patients compared with the patients with stable angina and the healthy control subjects. In addition, plasma MPO levels correlated with plasma IL-17 levels in all study participants. It is concluded that MPO and IL-17 are powerful indicators of acute coronary inflammation, however the data set was very small, so larger prospective studies are required.

Allogeneic mesenchymal stem cells transplantation in treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disorder of the central nervous system. Umbilical cord derived mesenchymal stem cells are immunosuppressive. We transplanted mesenchymal stem cells in a patient with refractory progressive MS, and the disease course was stabilized after the transplantation. We postulate that mesenchymal stem cells have a potent immunosuppressive effect in vivo.

Core-shell polymer nanorods by a two-step template wetting process

One-dimensional core-shell polymer nanowires offer many advantages and great potential for many different applications. In this paper we introduce a highly versatile two-step template wetting process to fabricate two-component core-shell polymer nanowires with controllable shell thickness. PLLA and PMMA were chosen as model polymers to demonstrate the feasibility of this process. Solution wetting with different concentrations of polymer solutions was used to fabricate the shell layer and melt wetting was used to fill the shell with the core polymer. The shell thickness was analyzed as a function of the polymer solution concentration and viscosity, and the core-shell morphology was observed with TEM. This paper demonstrates the feasibility of fabricating polymer core-shell nanostructures using our two-step template wetting process and opens the arena for optimization and future experiments with polymers that are desirable for specific applications.