401. Type 2 inositol 1,4,5-trisphosphate receptor inhibits the progression of pulmonary arterial hypertension via calcium signaling and apoptosis.
- Author
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Shibata A, Uchida K, Kodo K, Miyauchi T, Mikoshiba K, Takahashi T, and Yamagishi H
- Subjects
- Animals, Calcium Signaling, Cells, Cultured, Disease Models, Animal, Disease Progression, Hypertension, Pulmonary metabolism, Hypertension, Pulmonary pathology, Immunohistochemistry, In Situ Nick-End Labeling, Male, Mice, Mice, Inbred C57BL, Muscle, Smooth, Vascular pathology, Pulmonary Artery pathology, Vasoconstriction, Apoptosis, Calcium metabolism, Hypertension, Pulmonary physiopathology, Inositol 1,4,5-Trisphosphate Receptors metabolism, Muscle, Smooth, Vascular metabolism, Pulmonary Artery physiopathology
- Abstract
Pulmonary arterial hypertension (PAH) is a progressive disease associated with vasoconstriction and remodeling. Intracellular Ca
2+ signaling regulates the contraction of pulmonary arteries and the proliferation of pulmonary arterial smooth muscle cells (PASMCs); however, it is not clear which molecules related to Ca2+ signaling contribute to the progression of PAH. In this study, we found the specific expression of type 2 inositol 1,4,5-trisphosphate receptor (IP3 R2), which is an intracellular Ca2+ release channel, on the sarco/endoplasmic reticulum in mouse PASMCs, and demonstrated its inhibitory role in the progression of PAH using a chronic hypoxia-induced PAH mouse model. After chronic hypoxia exposure, IP3 R2-/- mice exhibited the significant aggravation of PAH, as determined by echocardiography and right ventricular hypertrophy, with significantly greater medial wall thickness by immunohistochemistry than that of wild-type mice. In IP3 R2-/- murine PASMCs with chronic hypoxia, a TUNEL assay revealed the significant suppression of apoptosis, whereas there was no significant change in proliferation. Thapsigargin-induced store-operated Ca2+ entry (SOCE) was significantly enhanced in IP3 R2-/- PASMCs in both normoxia and hypoxia based on in vitro fluorescent Ca2+ imaging. Furthermore, the enhancement of SOCE in IP3 R2-/- PASMCs was remarkably suppressed by the addition of DPB162-AE, an inhibitor of the stromal-interacting molecule (STIM)-Orai complex which is about 100 times more potent than 2-APB. Our results indicate that IP3 R2 may inhibit the progression of PAH by promoting apoptosis and inhibiting SOCE via the STIM-Orai pathway in PASMCs. These findings suggest a previously undetermined role of IP3 R in the development of PAH and may contribute to the development of targeted therapies.- Published
- 2019
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