miRNA-30a-5p-mediated silencing of Beta2/NeuroD expression is an important initial event of glucotoxicity-induced beta cell dysfunction in rodent models

Abstract

Aims/hypothesis The loss of beta cell function is a critical factor in the development of type 2 diabetes. Glucotoxicity plays a major role in the progressive deterioration of beta cell function and development of type 2 diabetes mellitus. Here we demonstrate that microRNA (miR)-30a-5p is a key player in early-stage glucotoxicity-induced beta cell dysfunction. Methods We performed northern blots, RT-PCR and western blots in glucotoxicity-exposed primary rat islets and INS-1 cells. We also measured glucose-stimulated insulin secretion and insulin content. In vivo approaches were used to evaluate the role of miR-30a-5p in beta cell dysfunction.Results miR-30a-5p expression was increased in beta cells after exposure to glucotoxic conditions, and exogenous miR-30a-5p overexpression also induced beta cell dysfunction in vitro. miR-30a-5p directly suppressed expression of Beta2/NeuroD (also known as Neurod1) by binding to a specific binding site in its 3′-untranslated region. After restoration of Beta2/NeuroD expression by knockdown miR-30a-5p or transfection of the Beta2/NeuroD gene, beta cell dysfunction, including decreased insulin content, gene expression and glucose-stimulated insulin secretion, recovered. Glucose tolerance and beta cell dysfunction improved on direct injection of Ad-si30a-5p into the pancreas of diabetic mice. Conclusions/interpretation Our data demonstrate that miR30a-5p-mediated direct suppression of Beta2/NeuroD gene expression is an important initiation step of glucotoxicityinduced beta cell dysfunction.

Clinical verification of a novel urinary microRNA panal: 133b, -342 and -30 as biomarkers for diabetic nephropathy identified by bioinformatics analysis

“…The levels of urinary miR-30a-5p, was reported to be associated with FSGS disease activity and marginally predicted the response to steroid treatment. In the event that miR-30a-5p-mediated direct suppression of Beta2/NeuroD gene expression, itwas reported as an initiation step of glucotoxicity-induced beta cell dysfunction in rodent model [35]. Equally important, miR-30a negatively regulates TGF-b1 and thus may act as a therapeutic target for peritoneal fibrosis [36].…”

Mechanisms of β-cell dedifferentiation in diabetes: recent findings and future research directions

“…3). In addition, upregulation of miR-30a-5p by high glucose levels in INS1 cells and rat islets has been shown to inhibit Neurod1 expression (Kim et al 2013) (Fig. 3).…”

“…Similarly, increased DNA methylation in the Glp1r promoter has been observed in the islets of human T2D subjects (Hall et al 2013). We have highlighted in the previous section the implication of several miRNAs in the inhibition of insulin gene expression and upstream transcription factors (Fred et al 2010, Kim et al 2013, Xu et al 2013, Sebastiani et al 2015. In addition, various miRNAs upregulated in the islets of GK rats have been shown to target transport and secretory pathway genes (Esguerra et al 2011).…”

Regulatory Roles of MicroRNAs in Diabetes

“…Aside from the above, many other miRNAs are involved in pancreatic function, especially insulin secretion (e.g., miR-375 , -184, -33 , -187 , -29a , and -30a ) [28,29,30,31,32,33,34,35,36,37]. For example, although miR-29 is mentioned above in regard to its role in regulating β-cell proliferation, it has also been shown in multiple reports to negatively regulate insulin secretion by directly targeting Stx-1a , a t-SNARE protein involved in insulin exocytosis [31], and Mct1 , which may affect insulin secretion [32].…”