Elevated circulating stearic acid leads to a major lipotoxic effect on mouse pancreatic beta cells in hyperlipidaemia via a miR-34a-5p-mediated PERK/p53-dependent pathway

Abstract

Aims/hypothesis Serum stearic acid (C18:0) is elevated in individuals with hyperlipidaemia and type 2 diabetes. However, the lipotoxicity induced by increased stearic acid in beta cells has not been well described. This study aimed to examine the adverse effects of stearic acid on beta cells and the potential mechanisms through which these are mediated. Methods Three groups of C57BL/6 mice were fed a normal diet or a high-stearic-acid/high-palmitic-acid diet for 24 weeks, respectively. The microRNA (miR) profiles of islets were determined by microarray screening. Islet injury was detected with co-staining using the TUNEL assay and insulin labelling. A lentiviral vector expressing anti-miRNA-34a-5p oligonucleotide (AMO-34a-5p) was injected into mice via an intraductal pancreatic route. Results In both mouse islets and cultured rat insulinoma INS-1 cells, stearic acid exhibited a stronger lipotoxic role than other fatty acids, owing to repression of B cell CLL/ lymphoma 2 (BCL-2) and BCL-2-like 2 (BCL-W) by stearic acid stimulation of miR-34a-5p. The stearic-acid-induced lipotoxicity and reduction in insulin secretion were alleviated by AMO-34a-5p. Further investigations in INS-1 cells revealed that p53 was involved in stearic-acid-induced elevation of miR-34a-5p, owing in part to activation of protein kinaselike endoplasmic reticulum kinase (PERK). Conversely, silencing PERK alleviated stearic-acid-induced p53, miR-34a-5p and lipotoxicity. Conclusions/interpretation These findings provide new insight for understanding the molecular mechanisms underlying not only the deleterious impact of stearic-acid-induced lipotoxicity but also apoptosis in beta cells and progression to type 2 diabetes.

MicroRNA-1185 Promotes Arterial Stiffness though Modulating VCAM-1 and E-Selectin Expression

“…Primer sequences are listed in Table 1. Real-time PCR was performed with the SYBR Green PCR Master Mix (Applied Biosystems, Foster City, CA, USA) [37]. …”

Transgene and islet cell delivery systems using nano-sized carriers for the treatment of diabetes mellitus

“…Several other miRNAs, including miR-9, miR-124a, miR-126, miR-34a, and miR21, have been studied for their roles in glucose regulation or pancreatic β cell function; however, there are few studies on their therapeutic effects for diabetes mellitus [1,73–77]. Further studies on the effects of gene therapies using targeted miRNA for the treatment of diabetes mellitus in vivo are required.…”

MicroRNA-1185 Induces Endothelial Cell Apoptosis by Targeting UVRAG and KRIT1

“…Stearic acid and Palmitic acid (Sigma, St Louis, MO, USA) were prepared as previously described [22]. In brief, stearic acid or palmitic acid (Sigma, St Louis, MO) complex with BSA (3 mmol/l fatty acid: 1.5 mmol/l BSA) was dissolved in ethanol and saponified with sodium hydroxide.…”

“…Lactate dehydrogenase (LDH) release was used to measure cellular injury, and propidium iodide (PI) and Hoechst staining were performed to assess cell apoptosis, as described in our earlier study [22]. To measure LDH release, an LDH assay kit (Thermo Fisher Scientific Inc.) was used to examine culture media.…”

“…Western blot was performed as previously described [22] using the following primary antibodies: Caspase-3 and UVRAG (Cell Signaling Technology, Danvers, MA, USA) as well as KRIT1 and β-actin (Santa Cruz Biotechnology, Dallas, TX, USA). Anti-goat or anti-rabbit alkaline phosphatase-conjugated antibody (Promega, Madison, WI, USA) was used as a secondary antibody.…”