Endothelial Upregulation of Mechanosensitive Channel Piezo1 in Pulmonary Hypertension

Abstract

RationaleThe Piezo channel family (Piezo1 and Piezo2), one of the most important family of mechanosensing ion channels. Surprisingly, there are no studies on Piezo in the pulmonary hypertension. We focus on Piezo1 because of its imprtance in vascular deveopment, especially in endothelial cells. Our working hypothesis is that upregulated Piezo1 may be a critical pathogenic mechanism that contributes to augmented Ca2+ influx and excessive PAEC proliferation or apoptosis in patients with IPAH.MethodsRNA levels of Piezo1 and Piezo2 was quantified by RT‐PCR Analysis. Protein levels of Piezo1, bax, bcl‐2, Calpain‐1 and Calpain‐2 was quantified by Western blot analysis. adult Male C57BL/6 mice (6–8 weeks) were exposed to persistent chronic hypoxia (10% O2) for 21 days to establish hypoxia‐induced PH. For Sugen 5416/hypoxia (SuHx) induced‐PH rat model, SD rats (age, 6–8 weeks old) were either injected s.c. with 20 mg·kg−1 SU5416 (Sigma‐Aldrich, St. Louis, MO, USA) or vehicle, exposed to hypoxic conditions for 3 weeks (10% O2) and returned to normoxic condition (21% O2) for 2 weeks. In the MCT group, a single intraperitoneal injection of MCT (60 mg/kg, Sigma Aldrich) was given at day 1 to establish the MCT‐induced PH.ResultsPiezo1 and Piezo2 have high expression in rat lung tissue and human PAEC, and also Piezo1 has significantly higher mRNA levels in both human PASMC and PAEC than Piezo2 (n=5, p<0.01). Upregulated Piezo1 in whole‐lung tissue (mainly containing ECs) from MCT‐mediated PH (MCT‐PH) compared to normal control rats (1.00±0.07; 4.74±0.41, n>5, p<0.001). Compared to controls, Piezo1 was increased in whole‐lung tissues in hypoxic mice (1.00±0.07; 4.74±0.41, n>5, p<0.01) and SuHx rats (1.00±0.15; 1.99±0.31, n>5, p<0.01). Also, compared to normoxia condition, increased Piezo1 was associated with a increased Calpain‐1 and Calpain‐2 treated with hypoxia (3% O2 for 72 hours) (1.00±0.16; 4.14±0.75; 1.00±0.14, 2.32±0.35; 1.00±0.07; 1.74±0.14, n>5, p<0.01). Moreover, PAECs from IPAH patients exhibited significant elevation of Piezo1 compared to normal control subjects (1.00±0.09; 6.20±1.78, n=5, p<0.01).ConclusionsThese results are the first to implicate that Piezo1 as a mechanosensor may play an important role in the development of pulmonary hypertension via, at least in part, induction of PAEC apoptosis and enhancement of Ca2+ in PAECs. Piezo1 may be involved in the transcriptional regulation under hypoxia and play critical roles in the development of PH. Therefore, further studies are needed to identify the potential contribution of Piezo1 in PH.Support or Funding InformationNone.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.