Nucleocytoplasmic Shuttling of TAX1BP3: an Indispensable Player in Vascular Proliferative Diseases by Regulating YAP-TEAD Transcriptional Activity [ATAC-seq]

BACKGROUND: The phenotypic switching of vascular smooth muscle cells (VSMCs) plays a crucial role in vascular homeostasis. Protein-protein interactions (PPIs) mediated by PDZ domains is essential for cardiac functions. However, little is known about the role of PDZ proteins in regulating the phenotypic switching of VSMCs. In this study, we aim to explore the role of TAX1BP3, a singular PDZ protein, in maintaining the contractile phenotype of VSMCs. METHODS: Subcellular localization of TAX1BP3 was assessed in isolated VSMCs and arteries from mice or donors with in-stent restenosis and atherosclerosis. VSMC-specific Tax1bp3 knockout mice were generated to determine the relevant phenotypes in a carotid artery wire injury model. RNA sequencing, ATAC-sequencing, computational prediction of complex structures, and coCo-immunoprecipitation (Co-IP) were performed to elucidate the underlying molecular mechanisms. AAV-mediated Tax1bp3 gene delivery and recombinant TAX1BP3 were employed to investigate the potential translational relevance. RESULTS: TAX1BP3 exhibited dynamic nucleocytoplasmic shuttling during phenotypic switching of VSMCs. Deficiency of TAX1BP3 facilitated the transition from a contractile to a synthetic phenotype and aggravated neointima formation following vascular injury in mice. The integration of RNA sequencing and ATAC sequencing unveiled that TAX1BP3 primarily regulated the cell cycle progression and cell proliferation of VAMCs through YAP-TEAD transcription activity. The computational prediction of TAX1BP3/YAP1 complex structures and protein interaction related experiments revealed TAX1BP3 and TEAD1 compete for binding to YAP through its TEAD binding domain via a non-canonical PDZ manner. AAV-mediated Tax1bp3 gene delivery markedly attenuated post-injury neointima formation and the progression of atherosclerosis. Recombinant TAX1BP3 administration effectively reduced VSMCs proliferation and intimal hyperplasia following vascular injury in vitro and in vivo. CONCLUSIONS: Our results identified TAX1BP3 , a novel nucleocytoplasmic protein, a singular PDZ protein, that competitively interacts with YAP/-TEAD complex in a non-canonical PDZ manner and exerted its protective role in phenotypic switching and vascular intimal hyperplasia primarily through the regulation of cell proliferation.