Elevated Glucose Levels Promote Contractile and Cytoskeletal Gene Expression in Vascular Smooth Muscle via Rho/Protein Kinase C and Actin Polymerization

Tran Thi Hien,Karolina M Turczyńska,Diana Dahan,Mari Ekman,Mario Grossi,Johan Sjögren,Johan Nilsson,Thomas Braun,Thomas Boettger,Eliana Garcia-Vaz,Karin Stenkula,Karl Swärd,Maria F Gomez,Sebastian Albinsson

doi:10.1074/jbc.m115.654384

Abstract

Both type 1 and type 2 diabetes are associated with increased risk of cardiovascular disease. This is in part attributed to the effects of hyperglycemia on vascular endothelial and smooth muscle cells, but the underlying mechanisms are not fully understood. In diabetic animal models, hyperglycemia results in hypercontractility of vascular smooth muscle possibly due to increased activation of Rho-kinase. The aim of the present study was to investigate the regulation of contractile smooth muscle markers by glucose and to determine the signaling pathways that are activated by hyperglycemia in smooth muscle cells. Microarray, quantitative PCR, and Western blot analyses revealed that both mRNA and protein expression of contractile smooth muscle markers were increased in isolated smooth muscle cells cultured under high compared with low glucose conditions. This effect was also observed in hyperglycemic Akita mice and in diabetic patients. Elevated glucose activated the protein kinase C and Rho/Rho-kinase signaling pathways and stimulated actin polymerization. Glucose-induced expression of contractile smooth muscle markers in cultured cells could be partially or completely repressed by inhibitors of advanced glycation end products, L-type calcium channels, protein kinase C, Rho-kinase, actin polymerization, and myocardin-related transcription factors. Furthermore, genetic ablation of the miR-143/145 cluster prevented the effects of glucose on smooth muscle marker expression. In conclusion, these data demonstrate a possible link between hyperglycemia and vascular disease states associated with smooth muscle contractility.

Highlights

Diabetes confers a 2– 4-fold excess risk for a wide range of cardiovascular diseases, including macrovascular complications leading to coronary heart disease and ischemic stroke, as well as microvascular diseases, such as nephropathy and retinopathy [1, 2]
These analyses show that myocardin/MRTF/serum response factor (SRF) targets constitute a major transcriptomic signature in vascular smooth muscle cells exposed to high glucose
We have demonstrated that PKC/Rho activation by glucose can promote actin polymerization and expression of contractile and cytoskeletal markers in cultured smooth muscle cells

Summary

Introduction

Diabetes confers a 2– 4-fold excess risk for a wide range of cardiovascular diseases, including macrovascular complications leading to coronary heart disease and ischemic stroke, as well as microvascular diseases, such as nephropathy and retinopathy [1, 2]. It has been well established that hyperglycemia results in vascular hyperreactivity in diabetic patients [7] and animal models (8 –10) Part of this effect may be attributed to a decrease in nitric oxide (NO) bioavailability as well as a reduced response of vascular smooth muscle cells to NO [11]. In addition to calcium sensitization, activation of the Rho/ Rho-kinase pathway in vascular smooth muscle cells promotes actin polymerization, an effect that plays a major role in the regulation of smooth muscle gene expression and activates myocardin-related transcription factors (MRTFs, known as MKL1/2), co-factors to serum response factor (SRF) [18, 19]. We aimed to determine the effects of extracellular glucose on vascular smooth muscle contractile differentiation This was investigated using isolated smooth muscle cells in culture, arteries from hyperglycemic Akita mice, and mammary arteries from diabetic patients

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Conclusion