Regulation of Vascular Smooth Muscle Cell Dysfunction Under Diabetic Conditions by miR-504

Abstract

Objectives Diabetes accelerates pro-atherogenic and pro-inflammatory phenotype of VSMC associated with vascular complications. Evidence shows that microRNAs (miRNAs) play key roles in VSMC functions, but their role under diabetic conditions is unclear. We profiled miRNAs in VSMC from diabetic mice and examined their role in VSMC dysfunction. Approach and Results High throughput small RNA-sequencing identified 135 differentially expressed miRNAs in VSMC from type-2 diabetic db/db mice (db/dbVSMC) versus non-diabetic db/+ mice. Several of these miRNAs were known to regulate VSMC functions. We further focused on miR-504, because it was highly upregulated in db/dbVSMC, and its function in VSMC is unknown. miR-504 and its host gene Fgf13 were significantly increased in db/dbVSMC and in aortas from db/db mice. Bioinformatics analysis predicted that miR-504 targets including signaling adaptor Grb10 and transcription factor Egr2 could regulate growth factor signaling. We experimentally validated Grb10 and Egr2 as novel targets of miR-504. Overexpression of miR-504 in VSMC inhibited contractile genes, and enhanced ERK1/2 activation, proliferation and migration. These effects were blocked by miR-504 inhibitors. Grb10 knockdown mimicked miR-504 functions and increased inflammatory genes. Egr2 knockdown inhibited anti-inflammatory Socs1 and increased pro-inflammatory genes. Furthermore, high-glucose and palmitic acid upregulated miR-504 and inflammatory genes, but downregulated Grb10. Conclusions Diabetes mis-regulates several miRNAs including miR-504 that can promote VSMC dysfunction. Since changes in many of these miRNAs are sustained in diabetic VSMC even after in vitro culture, they may be involved in metabolic memory of vascular complications. Targeting such mechanisms could offer novel therapeutic strategies for diabetic complications.

miRNA Regulation of the Hyperproliferative Phenotype of Vascular Smooth Muscle Cells in Diabetes

“…However, there is scant current knowledge about the role of miRNAs in VSMC dysfunction in diabetic vascular disease. Recently, it has been reported that DM misregulates miR-504, which promotes VSMC dysfunction in db/db mice with type 2 DM (T2DM) (17). However, it is likely that the detrimental diabetic phenotype of VSMCs in vasculoproliferative disease is mediated by multiple miRNAs whose contemporary dysregulation act together to alter the multifactorial vascular response in diabetes.…”

Impact of Diabetes Mellitus

“…9 Reddy and colleagues showed that 135 miRNAs were differentially regulated in SMC cultured from thoracic aortas from diabetic db/db mice, as compared to SMC cultured from non-diabetic db/+ controls. The diabetes-induced increases in miR504 levels were further validated, and overexpression of miR504 was demonstrated to stimulate proliferation and migration of SMC.…”

Knockout of the X‐linkedFgf13in the hypothalamic paraventricular nucleus impairs sympathetic output to brown fat and causes obesity

“…Rather, their best characterized function is as modulators of voltage-gated Na + channels (Na V s) (9), and mutations that affect their Na V modulatory ability have been identified in cardiac arrhythmias and neurologic diseases such as Brugada syndrome, autosomal dominant cerebral ataxia, and epilepsy (10)(11)(12). Beyond regulation of Na V s, FGF13, encoded by Fgf13 on the X chromosome, can regulate other voltage-gated ion channels (13,14) and appears to affect a number of other cellular processes and contribute to physiology or disease states, including cancer (15), hypertrichosis (16), smooth and skeletal muscle cell development (17,18), microtubule stabilization in developing neurons (19), and protection from mechanical stress in cardiomyocytes by regulation of caveolae (20). These observations suggest that the full complement of FGF13 functions is not fully defined.…”