Long Non-coding RNA GAS5 Maintains Insulin Secretion by Regulating Multiple miRNAs in INS-1 832/13 Cells

Abstract

Type-2 diabetes mellitus (T2DM) is a complex disease characterized by reduced pancreatic islets β-cell mass and impaired insulin release from these cells. Non-coding RNAs, including microRNAs (miRNA) and long non-coding RNAs (lncRNAs), play a role in the progression of T2DM. Decreased serum lncRNA GAS5 levels were reported to be associated with T2DM. However, the role of GAS5 in regulating islet cell functions remain unknown. In this study, we found that the serum levels of GAS5 were significantly lower in patients with T2DM compared with healthy control subjects, and the low serum GAS5 levels were associated with high levels of HbAlc and fasting glucose in patients with T2DM. In addition, we found that serum GAS5 levels were negatively correlated with the serum levels of miR-29a-3p, miR-96-3p, and miR-208a-3p in patients with T2DM. Consequently, using INS-1 832/13 rat β-cell line, we found that overexpression of GAS5 by lentivirus infection increased glucose-stimulated insulin secretion and insulin content compared with negative control, whereas knockdown of GAS5 expression reduced both them. Moreover, GAS5 interacted with miR-29a-3p, miR-96-3p, and miR-208a-3p in INS-1 832/13 cells, as judged by pull-down assay and dual luciferase reporter assay. GAS5 overexpression caused the decrease in expression of miR-29a-3p, miR-96-3p, and miR-208a-3p in INS-1 832/13 cells and conversely caused the increase in expression of insulin receptor, insulin receptor substrate, and phosphoinositide-3-kinase regulatory subunit 1. Thus, these results reveal a novel mechanism whereby GAS5 is involved in maintaining insulin secretion and may represent a novel therapeutic target for T2DM.

Long Non-Coding RNAs (lncRNAs) in Cardiovascular Disease Complication of Type 2 Diabetes

“…In a study of the T2D mouse model, lncRNA GAS5 expression was lower in the islets of T2D mice, and silencing of this lncRNA expression caused impaired insulin synthesis and secretion in the MIN6 cells [ 46 ]. A similar observation was seen in a study of T2D patients, in which the circulating expression of GAS5 was reduced in T2D patients [ 47 ]. Silencing of GAS5 expression in the rat islet cell line reduced the expression of multiple microRNAs (miR-29a-3p, miR-96-3p, and miR-208a-3p) and subsequently reduced these microRNAs’ targets expressions, including the insulin receptor, insulin receptor substrate, and phosphoinositide-3-kinase regulatory subunit-1 [ 47 ].…”

“…A similar observation was seen in a study of T2D patients, in which the circulating expression of GAS5 was reduced in T2D patients [ 47 ]. Silencing of GAS5 expression in the rat islet cell line reduced the expression of multiple microRNAs (miR-29a-3p, miR-96-3p, and miR-208a-3p) and subsequently reduced these microRNAs’ targets expressions, including the insulin receptor, insulin receptor substrate, and phosphoinositide-3-kinase regulatory subunit-1 [ 47 ]. Transcriptomic profiling of the human islets also found LOC283177 is co-expressed with the insulin synthesis and secretion regulators, including MAP-kinase activating death domain ( MADD ), synaptotagmin 11 ( SYT11 ), and paired box 6 ( PAX6 ) [ 76 ].…”

Recovery of human type 2 diabetes beta cell function associates with transcriptomic signatures that point to novel therapeutic targets

“…Thus, SYT8 knockdown in islets from two human donors attenuated glucose-and arginine-induced insulin secretion by more than 50% (45). In INS-1 cells, overexpression of GAS5 increased insulin content and potentiated insulin release (46), while NR3C2 was associated with reduced insulin secretion (47). The up-regulation of PAX4 and down-regulation of FGF2 and MYC point to a restoration of a more differentiated beta cell phenotype (48,49).…”

The role of long non-coding RNAs in the regulation of pancreatic beta cell identity

“…In contrast with lncRNA-p3134 , the lncRNA GAS5 shows significantly reduced expression levels that correlate with HbA1c and T2D in humans, highlighting its potential use as a serum biomarker [ 54 , 55 ]. siRNA knockdown of Gas5 in MIN6 cells and mouse islets impaired expression of insulin mRNA and GSIS, as well as reducing expression of β-cell genes Pdx1 , MafA , NeuroD1 and Slc2a2 .…”

“…siRNA knockdown of Gas5 in MIN6 cells and mouse islets impaired expression of insulin mRNA and GSIS, as well as reducing expression of β-cell genes Pdx1 , MafA , NeuroD1 and Slc2a2 . In contrast, Gas5 overexpression improved cell viability, GSIS and insulin content [ 54 ]. Further investigation into Gas5 demonstrated a role in miRNA sequestration, as expression levels of three miRNAs with roles in insulin signalling, secretion and resistance (miR-29a-3p, miR-96-3p, and miR-208a-3p) were inversely correlated with Gas5 levels during Gas5 overexpression and knockdown.…”