miR-25 and miR-92b regulate insulin biosynthesis and pancreatic β-cell apoptosis

Abstract

Purpose. -Pancreatic β-cell failure is a central hallmark of the pathogenesis of diabetes mellitus; however, the molecular basis underlying chronic in ammation-caused β-cell failure remains unclear. This study reported here speci cally assessed the association between miR-25/miR-92b family and β-cell failure in diabetes.Methods. -IL-1β and two additional ER stress activators, palmitate and tunicamycin were applied to evaluate the expression level miR-25 by Taqman ® RT-PCR. Glucose-and potassium-stimulated insulin secretion assays were performed to assess β-cell function. Dual luciferase activity, and western blotting assays were utilized for miR-25 target gene veri cation. CCK-8 and TUNEL staining were used to evaluate β-cell viability and apoptosis. Results. -miRNA ChIP identi ed the increased level of miR-25 in INS-1 cells by IL-1β treatment. Expression levels of miR-25 were signi cantly upregulated with the treatment of IL-1β, palmitate or tunicamycin in both INS-1 cells and human islets. Ectopic elevation of miR-25 recapitulated most featured β-cell defects caused by IL-1β, including inhibition of insulin biosynthesis and increased β-cell apoptosis. These detrimental effects of miR-25 relied on its seed sequence recognition and repressed expression of its target genes Neurod1 and Mcl1. The miR-25/NEUROD1 axis reduced insulin biosynthesis via transcriptional regulation of β-cell speci c genes. The miR-25/MCL1 axis caused β-cell apoptosis in a caspase 3/PARP1-dependent manner. Comparable impairments were generated by miR-92b and miR-25, emphasizing the redundant biological roles of miRNA family members with the same seed sequence. Conclusion. -MiR-25/miR-92b family plays a major role in β-cell failure occurring under in ammation and diabetes states.Total RNA was extracted using TRIzol reagent (Invitrogen). Then Affymetrix miRNA ChIP was applied to ltrate abundance assessment of miRNA. TaqMan ® probes (Ambion, Foster City, CA) was used to detect miR-25 expression by using the THUNDERBIRD probe qPCR Mix (TOYOBO). For mRNA expression, SYBR Green qPCR Master Mix was used. The miRNA and mRNA expressions were detected on Roche Lightcycle480 II Sequence Detection System (Roche, Basel, Switzerland). Methods of miRNA and mRNA expression analysis were as described previously [12]. U6 and Actb were used as internal standards for miRNAs and mRNAs, respectively. Primers used are as follows:

Tropisetron improved testicular inflammation in the streptozotocin‐induced diabetic rats: The role of toll‐like receptor 4 (TLR4) and mir146a

“…miRNAs are involved in various physiological and pathological processes, including differentiation, inflammation, and apoptosis. [47,48] Different studies have suggested that miRNAs play key roles in the progression and inhibition of diabetes-induced organ damage. [49,50] To be more specific, miR-146 mediates many innate and adaptive immune and inflammatory responses in the body.…”

MiRNA dysregulation underlying common pathways in type 2 diabetes and cancer development: an Italian Association of Medical Oncology (AIOM)/Italian Association of Medical Diabetologists (AMD)/Italian Society of Diabetology (SID)/Italian Society of Endocrinology (SIE)/Italian Society of Pharmacology (SIF) multidisciplinary critical view

“… 33 , 39 miR-25 Its overexpression leads to inhibition of insulin biosynthesis and increased β-cell apoptosis. 27 miR-26 Reduces insulin promoter activity and insulin mRNA levels and consequently insulin content. 33 , 39 miR-29 family Its overexpression negatively affects GSIS and β-cell proliferation.…”

“… 26 miR-92b Its overexpression leads to inhibition of insulin biosynthesis and increased β-cell apoptosis. 27 miR-96 Represses β-cell function. 38 miR-124a Promotes β-cell dysfunction and death.…”

“… 26 Likewise, miR-25 and miR-92b expression is up-regulated by palmitate and pro-inflammatory cytokines, leading to inhibition of insulin biosynthesis and increased β-cell apoptosis. 27 Similarly, the miR-153 expression level is increased in interleukin-1β-treated β-cells and induces insulin secretion defects. 28 Furthermore, miR-320a is increased in the pancreatic β-cells from high-fat-diet (HFD)-treated mice and its overexpression in cultured β-cells initiates pancreatic islet dysfunction by increasing the reactive oxygen species level, inhibiting proliferation, and inducing apoptosis.…”

Non-coding RNAs in diabetes mellitus and diabetic cardiovascular disease

“…Inter-ethnic miRNA variants have been reported to be associated with regionally distributed diabetes; for example, miR-196a and miR-423 variants have been observed in T2DM patients in Saudi Arabia ( 88 ). Some miRNAs have been observed to be elevated during the development of DM, such as miR-25 and miR-92b ( 89 ). In general, these miRNAs with elevated expression promote the development of DM and play a role in the body’s IR, damage to β-cells, and other processes central to the development of diabetes.…”