Universities of Giessen and Marburg Lung Centre, German Center for Lung Research (DZL), 35392 Giessen, Germany.
Institute for Lung Health (ILH), 35392 Giessen, Germany.
Cells. 2020 Oct 13;9(10):2280. doi: 10.3390/cells9102280.
PKGs are serine/threonine kinases. PKG1 has two isoforms-PKG1α and β. Inositol trisphosphate receptor (IPR)-associated cGMP-kinase substrate 1 (IRAG1) is a substrate for PKG1β. IRAG1 is also known to further interact with IPRI, which mediates intracellular Ca release. However, the role of IRAG1 in PH is not known. Herein, WT and IRAG1 KO mice were kept under normoxic or hypoxic (10% O) conditions for five weeks. Animals were evaluated for echocardiographic variables and went through right heart catheterization. Animals were further sacrificed to prepare lungs and right ventricular (RV) for immunostaining, western blotting, and pulmonary artery smooth muscle cell (PASMC) isolation. IRAG1 is expressed in PASMCs and downregulated under hypoxic conditions. Genetic deletion of IRAG1 leads to RV hypertrophy, increase in RV systolic pressure, and RV dysfunction in mice. Absence of IRAG1 in lung and RV have direct impacts on PKG1β expression. Attenuated PKG1β expression in IRAG1 KO mice further dysregulates other downstream candidates of PKG1β in RV. IRAG1 KO mice develop PH spontaneously. Our results indicate that PKG1β signaling via IRAG1 is essential for the homeostasis of PASMCs and RV. Disturbing this signaling complex by deleting IRAG1 can lead to RV dysfunction and development of PH in mice.
PKGs 是丝氨酸/苏氨酸激酶。PKG1 有两种同工型-PKG1α 和 β。三磷酸肌醇受体（IPR）相关 cGMP-激酶底物 1（IRAG1）是 PKG1β 的底物。IRAG1 还已知与介导细胞内 Ca 释放的 IPRI 进一步相互作用。然而，IRAG1 在 PH 中的作用尚不清楚。在此，WT 和 IRAG1 KO 小鼠在常氧或缺氧（10%O）条件下饲养五周。评估动物的超声心动图变量并进行右心导管检查。动物进一步被处死以准备肺和右心室（RV）进行免疫染色、western blot 和肺动脉平滑肌细胞（PASMC）分离。IRAG1 在 PASMC 中表达，并在缺氧条件下下调。IRAG1 的基因缺失导致 RV 肥大、RV 收缩压升高和 RV 功能障碍。肺和 RV 中缺乏 IRAG1 对 PKG1β 表达有直接影响。IRAG1 KO 小鼠中 PKG1β 表达的减弱进一步使 RV 中 PKG1β 的其他下游候选物失调。IRAG1 KO 小鼠自发发展为 PH。我们的结果表明，IRAG1 介导的 PKG1β 信号对于 PASMC 和 RV 的内稳态是必不可少的。通过删除 IRAG1 破坏这个信号复合物可导致 RV 功能障碍和 PH 在小鼠中的发展。
