Phenotypic Switching of Vascular Smooth Muscle Cells in Duchenne Muscular Dystrophy

BackgroundExtensive studies have been conducted in skeletal muscle and myocardium affected by Duchenne Muscular Dystrophy (DMD) disease but there is a significant gap of research in the role of vascular smooth muscle cells (VSMCs) in DMD. Here, we investigated the role of dystrophin deficiency in the maintenance of VSMCs contractile phenotype. Methods12-14 months old mdx mice and DMD induced pluripotent stem cells (iPSC) derived VSMCs were used as disease models. Morphological and immunohistochemistry analyses were performed to determine histological changes and the expression of contractile markers. Transmission Electron Microscopy (TEM) was used to assess ultrastructural changes in the VSMCs. Mito-tracker staining and TUNEL staining were performed to determine mitochondria fission-fusion and apoptosis respectively. mRNA Sequencing for normal iPSC derived VSMCs (WT-VSMCs) and DMD iPSC derived VSMCs (DMD-VSMCs) with or without oxidative stress was performed. KEGG signaling pathway enrichment, Go function enrichment and Gene set enrichment analysis (GESA) were conducted to explore the potential mechanism responsible for these changes. In addition, transcription factor enrichment analysis was performed to unravel mechanistic pathways of regulatory networks. ResultsSpontaneous abnormal VSMCs proliferation, loss of vascular structure and degenerative changes occurred in VSMCs in aorta from 12-14 months old mdx mice. The DMD-VSMCs showed maturation defect, loss of mitochondrial hemostasis, and increased vulnerability to oxidative stress compared with WT-VSMCs. Transcriptome analysis revealed dysregulation of smooth muscle proliferation, differentiation, and vascular development in DMD-VSMCs. Transcriptional factor, target, and motif discovery analysis of the dysregulated gene set suggested potential contributions of transcriptional factors GADD45A, SOX9, TIA1, RBBP9 and FOXM to the phenotypes of DMD-VSMCs. Under oxidative stress, initiation of apoptotic process was significantly enhanced in DMD-VSMCs while their response to hypoxia and oxidative stress was downregulated. ConclusionsDystrophin deficiency induced VSMCs phenotype switching and disrupted mitochondrial metabolism. The findings in this study underscore the importance of vascular dysfunction in DMD disease and therapeutic interventions to restore VSMC phenotype may ameliorate the propensity of disease progression. It is suggested that the transcriptome analysis may allow the discovery of potential signaling pathways involved in the dysregulation of transcription factors.