Let7b-5p is Upregulated in the Serum of Emirati Patients with Type 2 Diabetes and Regulates Insulin Secretion in INS-1 Cells

Abstract

Let7b-5p is a member of the Let-7 miRNA family and one of the top expressed miRNAs in human islets that implicated in glucose homeostasis. The levels of Let7b-5p in type 2 diabetes (T2DM) patients or its role in β-cell function is still unclear. In the current study, we measured the serum levels of let7b-5p in Emirati patients with T2DM (with/without complications) and control subjects. Overexpression or silencing of let7b-5p in INS-1 (832/13) cells was performed to investigate the impact on insulin secretion, content, cell viability, apoptosis, and key functional genes. We found that serum levels of let7b-5p are significantly (p<0.05) higher in T2DM-patients or T2DM with complications compared to control subjects. Overexpression of let7b-5p increased insulin content and decreased glucose-stimulated insulin secretion, whereas silencing of let7b-5p reduced insulin content and secretion. Modulation of the expression levels of let7b-5p did not influence cell viability nor apoptosis. Analysis of mRNA and protein expression of hallmark genes in let7b-5p transfected cells revealed a marked dysregulation of Insulin, Pancreatic And Duodenal Homeobox 1 (PDX1), glucokinase (GCK), glucose transporter 2 (GLUT2), and INSR. In conclusion, an appropriate level of let7b-5p is essential to maintain β-cell function and may be regarded as a biomarker for T2DM.

miRNAs provide mechanisms for integrated control of endocrine pancreas homeostasis and metabolic disease pathogenesis: a narrative review

“…Other examples of how inappropriate levels of miRNA cause harmful effects on beta-cell proliferation come from models such as transgenic mice. This is the case of Let7b-5p, which is upregulated in the serum of T2D patients (111).…”

“…Let7b-5p is highly expressed in the serum of T2D patients, and its overexpression increases insulin biosynthesis but paradoxically inhibits GSIS, while let7b-5p inhibition decreases insulin content and partially restores GSIS. On a molecular level, let7b-5p plays a role in dysregulating the transcriptional level of Insulin, Pdx1, Gck, Glut2 and Insr (111).…”

Circulating Soluble ACE2 and Upstream microRNA Expressions in Serum of Type 2 Diabetes Mellitus Patients

“…For the calculation of serum miRNA levels, the relative quantification was calculated using the equation (RQ = 2 −Δ C t ), where the Δ C t is calculated based on the average Ct values of the healthy controls, as previously described [ 51 , 52 ]. Statistical analyses were done using GraphPad Prism 6 (GraphPad Software, San Diego, CA, USA).…”

Therapeutic Potential of miRNAs for Type 2 Diabetes Mellitus: An Overview

“… 109 Let-7b-5p was overexpressed in T2DM patients and proposed to modulate pancreatic insulin secretion. 110 However, the antimiR treatment for Let-7 has reduced the global Let-7 expression levels restoring the IS in mice muscles and livers. 96 Further, the treatment tends to increase muscle mass while managing the fat mass as per control.…”