Confluence does not affect the expression of miR-375 and its direct targets in rat and human insulin-secreting cell lines

MicroRNAs are small non-coding RNAs, which negatively regulate the expression oftarget genes. They have emerged as important modulators in beta cell compensationupon increased metabolic demand, failure of which leads to reduced insulin secretionand type 2 diabetes. To elucidate the function of miRNAs in beta cells, insulin-secretingcell lines, such as the rat insulinoma INS-1 832/13 and the human EndoC-βH1, arewidely used. Previous studies in the cancer field have suggested that miRNA expressionis influenced by confluency of adherent cells. We therefore aimed to investigate whetherone of the most enriched miRNAs in the pancreatic endocrine cells, miR-375, andtwo of its validated targets in mouse, Cav1 and Aifm1, were differentially-expressed incell cultures with different confluences. Additionally, we measured the expression ofother miRNAs, such as miR-152, miR-130a, miR-132, miR-212 and miR-200a, withknown roles in beta cell function. We did not see any significant expression changesof miR-375 nor any of the two targets, in both the rat and human beta cell lines atdifferent confluences. Interestingly, among the other miRNAs measured, the expressionof miR-132 and miR-212 positively correlated with confluence, but only in the INS-1832/13 cells. Our results show that the expression of miR-375 and other miRNAs withknown roles in beta cell function is independent of, or at least minimally influencedby the density of proliferating adherent cells, especially within the confluence rangeoptimal for functional assays to elucidate miRNA-dependent regulatory mechanismsin the beta cell. © 2017 Ofori et al.publishersversionpublishe

Altered metabolism distinguishes high-risk from stable carotid atherosclerotic plaques.

Aims Identification and treatment of the rupture prone atherosclerotic plaque remains a challenge for reducing the bur- den of cardiovascular disease. The interconnection of metabolic and inflammatory processes in rupture prone plaques is poorly understood. Herein, we investigate associations between metabolite profiles, inflammatory mediators and vulnerability in carotid atherosclerotic plaques.Methods and results We collected 159 carotid plaques from patients undergoing endarterectomy and measured 165 different metabolites in a targeted metabolomics approach. We identified a metabolite profile in carotid plaques that associated with histologically evaluated vulnerability and inflammatory mediators, as well as presence of symptoms in patients. The distinct metabolite profiles identified in high-risk and stable plaques were in line with different transcription levels of metabolic enzymes in the two groups, suggesting an altered metabolism in high-risk plaques. The altered metabolic signature in high-risk plaques was consistent with a change to increased glycolysis, elevated amino acid utilization and decreased fatty acid oxidation, similar to what is found in activated leucocytes and cancer cells.Conclusion These results highlight a possible key role of cellular metabolism to support inflammation and a high-risk phenotype of atherosclerotic plaques. Targeting the metabolism of atherosclerotic plaques with novel metabolic radiotracers or inhibitors might therefore be valid future approaches to identify and treat the high-risk atherosclerotic plaque

<em>MiR-184</em> regulates pancreatic &beta;-cell function according to glucose metabolism.

In response to fasting or hyperglycemia, the pancreatic &beta;-cell alters its output of secreted insulin; however the pathways governing this adaptive response are not entirely established. While the precise role of microRNAs (miRNAs) is also unclear, a recurring theme emphasizes their function in cellular stress responses. We recently showed that miR-184, an abundant miRNA in the &beta;-cell, regulates compensatory proliferation and secretion during insulin resistance. Consistent with previous studies showing miR-184 suppresses insulin release, expression of this miRNA was increased in islets after fasting, demonstrating an active role in the &beta;-cell as glucose levels lower and the insulin demand ceases. Additionally, miR-184 was negatively regulated upon administration of a sucrose-rich diet in Drosophila demonstrating strong conservation of this pathway through evolution. Furthermore, miR-184 and its target Argonaute2 (Ago2) remained inversely correlated as concentrations of extracellular glucose increased, underlining a functional relationship between this miRNA and its targets. Lastly, restoration of Ago2 in the presence of miR-184 rescued suppression of miR-375-targeted genes suggesting these genes act in a coordinated manner during changes in the metabolic context. Together, these results highlight the adaptive role of miR-184 according to glucose metabolism and suggest the regulatory role of this miRNA in energy homeostasis is highly conserved