Mitochondrial protein IF1 is a potential regulator of glucagon-like peptide (GLP-1) secretion function of the mouse intestine

IF1 (ATPIF1) is a nuclear DNA-encoded mitochondrial protein whose activity is inhibition of the F

Effect of miR-425-5p on GLP-1 secretion in intestinal L cells induced by lipopolysaccharide and its mechanism / 中华内分泌代谢杂志

Objective:To investigate the effect of miR-425-5p on glucagon-like peptide-1(GLP-1) secretion in intestinal L cells induced by lipopolysaccharide(LPS), and to explore its mechanism.Methods:GLUTag cells of intestinal L cell line were incubated with LPS to determine the levels of miR-425-5p and GLP-1. Cell viability was determined by MTT assay, and cell apoptosis was detected by flow cytometry. Quantitative real time-PCR and western blot were performed to determine the expressions of miR-425-5p, phosphatase and tensin homology(PTEN), proglucagon, and GLP-1. Activity of Wnt/β-catenin signaling pathway was determined by detecting TOP/FOP ratio. Interaction among miR-425-5p, PTEN, and β-catenin was analyzed using luciferase activity assay and chromatin immunoprecipitation(ChIP)assay.Results:In GLUTag cells, with the elevation of LPS concentration, the expression of miR-425-5p and the apoptosis rate were increased, while the level of active GLP-1 and the cell viability were decreased. MiR-425-5p was involved in the regulation of LPS on GLP-1 secretion and intestinal L cell viability. Inhibition of miR-425-5p reduced the mRNA expression of proglucagon and the TOP/FOP ratio, increased PTEN protein level, and inhibited cell viability. In LPS-treated GLUTag cells, miR-425-5p increased the level of β-catenin by targeting PTEN, and β-catenin acted as a cis-acting element to induce the transcription of proglucagon and promote the secretion of GLP-1.Conclusion:In LPS-induced intestinal L cells, miR-425-5p promotes the expression of GLP-1 by targeting PTEN to modulate β-catenin.

Prognostic Significance of Defining L-Cell Type on the Biologic Behavior of Rectal Neuroendocrine Tumors in Relation with Pathological Parameters / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: In 2010, the World Health Organization categorized L-cell type neuroendocrine tumors (NETs) as tumors of uncertain malignancy, while all others were classified as malignant. However, the diagnostic necessity of L-cell immunophenotyping is unclear, as are tumor stage and grade that may guide diagnosis and management. To clarify the predictive markers of rectal neuroendocrine neoplasms (NENs), 5- and 10-year overall survival (OS) was analyzed by pathological parameters including L-cell phenotype. MATERIALS AND METHODS: A total of 2,385 rectal NENs were analyzed from our previous multicenter study and a subset of 170 rectal NENs was immunophenotyped. RESULTS: In univariate survival analysis, tumor grade (p 10, is useful in defining L-Cell type. In this study, an L-cell immunophenotype was found in 83.5% of all rectal NENs and most, but not all L-cell type tumors were NET G1, small (< 10 mm) and confined to the mucosa/submucosa. CONCLUSION: From these results, the biological behavior of rectal NENs does not appear to be determined by L-cell type alone but instead by a combination of pathological parameters.

Insulin is secreted upon glucose stimulation by both gastrointestinal enteroendocrine K-cells and L-cells engineered with the preproinsulin gene

Transgenic mice carrying the human insulin gene driven by the K-cell glucose-dependent insulinotropic peptide (GIP) promoter secrete insulin and display normal glucose tolerance tests after their pancreatic p-cells have been destroyed. Establishing the existence of other types of cells that can process and secrete transgenic insulin would help the development of new gene therapy strategies to treat patients with diabetes mellitus. It is noted that in addition to GIP secreting K-cells, the glucagon-like peptide 1 (GLP-1) generating L-cells share/ many similarities to pancreatic p-cells, including the peptidases required for proinsulin processing, hormone storage and a glucose-stimulated hormone secretion mechanism. In the present study, we demonstrate that not only K-cells, but also L-cells engineered with the human preproinsulin gene are able to synthesize, store and, upon glucose stimulation, release mature insulin. When the mouse enteroendocrine STC-1 cell line was transfected with the human preproinsulin gene, driven either by the K-cell specific GIP promoter or by the constitutive cytomegalovirus (CMV) promoter, human insulin co-localizes in vesicles that contain GIP (GIP or CMV promoter) or GLP-1 (CMV promoter). Exposure to glucose of engineered STC-1 cells led to a marked insulin secretion, which was 7-fold greater when the insulin gene was driven by the CMV promoter (expressed both in K-cells and L-cells) than when it was driven by the GIP promoter (expressed only in K-cells). Thus, besides pancreatic p-cells, both gastrointestinal enteroendocrine K-cells and L-cells can be selected as the target cell in a gene therapy strategy to treat patients with type 1 diabetes mellitus.

Induction of apoptosis by wheat germ agglutinin in mouse fibroblast cell line L929 / 中国病理生理杂志

AIM: To investigate whether wheat germ agglutinin (WGA) could induce apoptosis in mouse fibroblast cell line L929 and the possible molecular mechanism underlying. METHODS: The cells were exposed to WGA or its succinylated form (sWGA) for 24 h and both attached cells and the cells in supernatant were collected. The percentages of apoptotic cells were estimated by flow cytometry after staining with propidium iodide. Cell morphology was observed under fluorescence microscope after staining the cells with acridine orange. RESULTS: WGA treatment resulted in significant increase of the low DNA content peak (sub-G 1) that representing apoptotic cells, whereas sWGA did not. Morphologic study demonstrated that exposure to WGA induced nuclear fragmentation while sWGA not. CONCLUSION: These results indicate that WGA (specific for both sialic acid and GlcNAc) induces apoptosis in L929 cells, whereas sWGA (specific only for GlcNAc) does not. It is possible that binding to sialic acid residues on the cell surface of L929 is essential for WGA to induce apoptosis. Apoptosis induction may be, at least in part, involved in the cytotoxicity of WGA. [