Biomaterial Database

Nuclear Smooth Muscle α-actin in Vascular Smooth Muscle Cell Differentiation. 2023

Callie S Kwartler, and Albert J Pedroza, and Anita Kaw, and Pujun Guan, and Shuangtao Ma, and Xue-Yan Duan, and Caroline Kernell, and Charis Wang, and Jose Emiliano Esparza Pinelo, and Mikayla S Borthwick, and Jiyuan Chen, and Yuan Zhong, and Sanjay Sinha, and Xuetong Shen, and Michael P Fischbein, and Dianna M Milewicz

Division of Medical Genetics, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030.

Missense variants throughout ACTA2, encoding smooth muscle α-actin (αSMA), predispose to adult onset thoracic aortic disease, but variants disrupting arginine 179 (R179) lead to Smooth Muscle Dysfunction Syndrome (SMDS) characterized by childhood-onset diverse vascular diseases. Our data indicate that αSMA localizes to the nucleus in wildtype (WT) smooth muscle cells (SMCs), enriches in the nucleus with SMC differentiation, and associates with chromatin remodeling complexes and SMC contractile gene promotors, and the ACTA2 p.R179 variant decreases nuclear localization of αSMA. SMCs explanted from a SMC-specific conditional knockin mouse model, Acta2, are less differentiated than WT SMCs, both in vitro and in vivo, and have global changes in chromatin accessibility. Induced pluripotent stem cells from patients with ACTA2 p.R179 variants fail to fully differentiate from neural crest cells to SMCs, and single cell transcriptomic analyses of an ACTA2 p.R179H patient's aortic tissue shows increased SMC plasticity. Thus, nuclear αSMA participates in SMC differentiation and loss of this nuclear activity occurs with ACTA2 p.R179 pathogenic variants.