Upregulation of Calcium Homeostasis Modulators in Contractile-To-Proliferative Phenotypical Transition of Pulmonary Arterial Smooth Muscle Cells.

Marisela Rodriguez,Moises Hernandez,Jiyuan Chen,Ning Lai,Ayako Makino,Tengteng Zhao,Jifeng Li,Sophia Parmisano,Patricia A Thistlethwaite,Aleksandra Babicheva,Angela Balistrieri,Mingmei Xiong,John Y.‐J Shyy ,Joe G.n Garcia ,Ellen C Breen ,Jian Wang ,Tatum S Simonson ,Pritesh Jain ,Daniela Valdez‐Jasso ,Jason X.‐J Yuan

doi:10.3389/fphys.2021.714785

Abstract

Excessive pulmonary artery (PA) smooth muscle cell (PASMC) proliferation and migration are implicated in the development of pathogenic pulmonary vascular remodeling characterized by concentric arterial wall thickening and arteriole muscularization in patients with pulmonary arterial hypertension (PAH). Pulmonary artery smooth muscle cell contractile-to-proliferative phenotypical transition is a process that promotes pulmonary vascular remodeling. A rise in cytosolic Ca2+ concentration [(Ca2+)cyt] in PASMCs is a trigger for pulmonary vasoconstriction and a stimulus for pulmonary vascular remodeling. Here, we report that the calcium homeostasis modulator (CALHM), a Ca2+ (and ATP) channel that is allosterically regulated by voltage and extracellular Ca2+, is upregulated during the PASMC contractile-to-proliferative phenotypical transition. Protein expression of CALHM1/2 in primary cultured PASMCs in media containing serum and growth factors (proliferative PASMC) was significantly greater than in freshly isolated PA (contractile PASMC) from the same rat. Upregulated CALHM1/2 in proliferative PASMCs were associated with an increased ratio of pAKT/AKT and pmTOR/mTOR and an increased expression of the cell proliferation marker PCNA, whereas serum starvation and rapamycin significantly downregulated CALHM1/2. Furthermore, CALHM1/2 were upregulated in freshly isolated PA from rats with monocrotaline (MCT)-induced PH and in primary cultured PASMC from patients with PAH in comparison to normal controls. Intraperitoneal injection of CGP 37157 (0.6 mg/kg, q8H), a non-selective blocker of CALHM channels, partially reversed established experimental PH. These data suggest that CALHM upregulation is involved in PASMC contractile-to-proliferative phenotypical transition. Ca2+ influx through upregulated CALHM1/2 may play an important role in the transition of sustained vasoconstriction to excessive vascular remodeling in PAH or precapillary PH. Calcium homeostasis modulator could potentially be a target to develop novel therapies for PAH.

Highlights

Pulmonary arterial hypertension (PAH) is a fatal and progressive disease in which increased pulmonary arterial pressure (PAP) is mainly due to increased pulmonary vascular resistance (PVR) (Runo and Loyd, 2003)
We first used an ex vivo model, freshly isolated PA and primary cultured pulmonary arterial smooth muscle cells (PASMCs) in media containing 10% fetal bovine serum (FBS) and growth factors, to identify the membrane receptors, ion channels and intracellular signaling proteins that are associated with the PASMC phenotypic transition from a contractile phenotype to a proliferative phenotype
Our results indicate that (i) Calcium homeostasis modulator 1 (CALHM1) and CALHM2, two voltage-activated and extracellular Ca2+-inhibited Ca2+ channels and adenosine triphosphate (ATP) release channels, are upregulated during the contractile-toproliferative phenotypical transition in PASMCs; (ii) upregulated CALHM1/2 are associated with upregulated AKT and mTOR as well as an increased phosphorylation of AKT (pAKT)/AKT and pAKT and mTOR (pmTOR)/mTOR ratio in proliferative PASMC compared to contractile PASMCs; (iii) inhibition of AKT/mTOR signaling with rapamycin

Summary

Introduction

Pulmonary arterial hypertension (PAH) is a fatal and progressive disease in which increased pulmonary arterial pressure (PAP) is mainly due to increased pulmonary vascular resistance (PVR) (Runo and Loyd, 2003). At the initial stage of the disease pathogenesis, sustained pulmonary vasoconstriction and attenuated pulmonary vasodilation may be the major cause for the elevated PVR and PAP in patients with PAH. Excessive pulmonary vascular remodeling in PAH is partially mediated by increased proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs) due to PASMC dedifferentiation from a contractile or quiescent phenotype to a proliferative or synthetic phenotype (Beamish et al, 2010; Fernandez et al, 2015). Vascular smooth muscle cells (SMCs) or PASMCs and their role in the development of PAH require further investigation due to their phenotypic diversity which performs both contractile and synthetic or proliferative functions (Rensen et al, 2007)

Objectives

Methods

Results

Conclusion