DOI: 10.6084/m9.figshare.24457488.v1
title: CDN1163 alleviates SERCA2 dysfunction-induced pulmonary vascular remodeling by inhibiting the phenotypic transition of pulmonary artery smooth muscle cells

description: Substitution of Cys<sup>674</sup> (C674) in the sarcoplasmic/endoplasmic reticulum Ca<sup>2+</sup> ATPase 2 (SERCA2) causes SERCA2 dysfunction which leads to activated inositol requiring enzyme 1 alpha (IRE1α) and spliced X-box binding protein 1 (XBP1s) pathway accelerating cell proliferation of pulmonary artery smooth muscle cells (PASMCs) followed by significant pulmonary vascular remodeling resembling human pulmonary hypertension. Based on this knowledge, we intend to investigate other potential mechanisms involved in SERCA2 dysfunction-induced pulmonary vascular remodeling. Heterozygous SERCA2 C674S knock-in (SKI) mice of which half of cysteine in 674 was substituted by serine to mimic the partial irreversible oxidation of C674 were used. The lungs of SKI mice and their littermate wild-type mice were collected for PASMC culture, protein expression, and pulmonary vascular remodeling analysis. SERCA2 dysfunction increased intracellular Ca<sup>2+</sup> levels, which activated Ca<sup>2+</sup>-dependent calcineurin (CaN) and promoted the nuclear translocation and protein expression of the nuclear factor of activated T-lymphocytes 4 (NFAT4) in an IRE1α/XBP1s pathway-independent manner. In SKI PASMCs, the scavenge of intracellular Ca<sup>2+</sup> by BAPTA-AM or inhibition of CaN by cyclosporin A can prevent PASMC phenotypic transition. CDN1163, a SERCA2 agonist, suppressed the activation of CaN/NFAT4 and IRE1α/XBP1s pathways, reversed the protein expression of PASMC phenotypic transition markers and cell cycle-related proteins, and inhibited cell proliferation and migration when given to SKI PASMCs. Furthermore, CDN1163 ameliorated pulmonary vascular remodeling in SKI mice. SERCA2 dysfunction promotes PASMC phenotypic transition and pulmonary vascular remodeling by multiple mechanisms, which could be improved by SERCA2 agonist CDN1163. <b>‘What is already known’</b>l The dysfunction of SERCA2 promotes PASMC hyperproliferation and pulmonary vascular remodeling through activation of the IRE1α/XBP1s pathway. l The dysfunction of SERCA2 promotes PASMC hyperproliferation and pulmonary vascular remodeling through activation of the IRE1α/XBP1s pathway. <b>‘What this study adds’</b>l The dysfunction of SERCA2 activates the Ca<sup>2+</sup>-dependent CaN-mediated NFAT4 pathway to promote the PASMC phenotypic transition.l Revitalization of SERCA2 suppresses PASMC phenotypic transition and pulmonary vascular remodeling caused by SERCA2 dysfunction. l The dysfunction of SERCA2 activates the Ca<sup>2+</sup>-dependent CaN-mediated NFAT4 pathway to promote the PASMC phenotypic transition. l Revitalization of SERCA2 suppresses PASMC phenotypic transition and pulmonary vascular remodeling caused by SERCA2 dysfunction. <b>‘Clinical significance’</b>l SERCA2 dysfunction-induced pulmonary vascular remodeling involves more than one mechanism, implicating that more drugable targets are to be discovered.l SERCA2 is a potential therapeutic target for preventing pulmonary vascular remodeling. l SERCA2 dysfunction-induced pulmonary vascular remodeling involves more than one mechanism, implicating that more drugable targets are to be discovered. l SERCA2 is a potential therapeutic target for preventing pulmonary vascular remodeling.