ABSTRACT
The aim of this study was to investigate the role and mechanism of terpinen-4-ol (T4O) on high glucose (HG) -induced calcification in vascular smooth muscle cell (VSMC). To investigate the role of T4O on HG-induced calcium deposition, osteogenic phenotypic transformation and mitochondrial dynamics in VSMC, Mdivi-1, a mitochondrial dynamin-related protein 1 (Drp-1) inhibitor, was used to analyze the correlation between mitochondrial dynamics and VSMC calcification and the role of T4O. Alizarin red S staining was used to observe calcium salt deposition and flow cytometry to detect intracellular Ca2+ content; Western blot and immunofluorescence were used to detect the expression of phenotypic switching-related markers α-smooth muscle actin (α-SMA), bone morphogenetic protein 2 (BMP2) and Runt related transcription factor 2 (Runx2), and mitochondrial dynamics-related markers mitofusin 1 (MFN1), mitofusin 2 (MFN2) and Drp-1. The results showed that low and high doses of T4O could inhibit HG-induced down-regulation of α-SMA, MFN1 and MFN2 expression levels, and up-regulation of BMP2, Runx2 and Drp-1 expression levels, reduce intracellular Ca2+ content and calcium salt deposition, and effectively inhibit HG-induced VSMC calcification and mitochondrial dynamics disorders. The T4O group, Mdivi-1 group and T4O+Mdivi-1 group were able to up-regulate the expression levels of HG-induced α-SMA, MFN1 and MFN2, down-regulate the protein expression levels of BMP2, Runx2 and Drp-1, and inhibit calcium salt deposition, and there was no significant difference between the above indexes in the T4O and T4O+Mdivi-1 groups. The above findings suggest that T4O can inhibit the expression level of Drp-1, regulate the disturbance of mitochondrial dynamics, and suppress HG-induced VSMC calcification.
ABSTRACT
Vascular smooth muscle cells (VSMCs) play a pivotal role in the stability and tonic regulation of vascular homeostasis. VSMCs can switch back and forth between highly proliferative (synthetic) and fully differentiated (contractile) phenotypes in response to changes in the vessel environment. Abnormal phenotypic switching of VSMCs is a distinctive characteristic of vascular disorders, including atherosclerosis, pulmonary hypertension, stroke, and peripheral artery disease; however, how the control of VSMC phenotypic switching is dysregulated under pathological conditions remains obscure. Canonical transient receptor potential (TRPC) channels have attracted attention as a key regulator of pathological phenotype switching in VSMCs. Several TRPC subfamily member proteins—especially TRPC1 and TRPC6—are upregulated in pathological VSMCs, and pharmacological inhibition of TRPC channel activity has been reported to improve hypertensive vascular remodeling in rodents. This review summarizes the current understanding of the role of TRPC channels in cardiovascular plasticity, including our recent finding that TRPC6 participates in aberrant VSMC phenotype switching under ischemic conditions, and discusses the therapeutic potential of TRPC channels.