Upregulation of eIF2α by m(6)A modification accelerates the proliferation of pulmonary artery smooth muscle cells in MCT-induced pulmonary arterial hypertension rats.

Pulmonary arterial hypertension (PAH) is a malignant cardiovascular disease. Eukaryotic initiation factor 2α (eIF2α) plays an important role in the proliferation of pulmonary artery smooth muscle cells (PASMCs) in hypoxia-induced pulmonary hypertension (HPH) rats. However, the regulatory mechanism of eIF2α remains poorly understood in PAH rats. Here, we discover eIF2α is markedly upregulated in monocrotaline (MCT)-induced PAH rats, eIF2α can be upregulated by mRNA methylation, and upregulated eIF2α can promote PASMC proliferation in MCT-PAH rats. GSK2606414, eIF2α inhibitor, can downregulate the expression of eIF2α and alleviate PASMC proliferation in MCT-PAH rats. And we further discover the mRNA of eIF2α has a common sequence with N 6-methyladenosine (m6A) modification by bioinformatics analysis, and the expression of METTL3, WTAP, and YTHDF1 is upregulated in MCT-PAH rats. These findings suggest a potentially novel mechanism by which eIF2α is upregulated by m6A modification in MCT-PAH rats, which is involved in the pathogenesis of PAH.

Zhang J ，Huang WQ ，Zhang YR ，Liang N ，Li NP ，Tan GK ，Gong SX ，Wang AP ... -  《-》

eIF2α promotes vascular remodeling via autophagy in monocrotaline-induced pulmonary arterial hypertension rats.

Guo L ，Li Y ，Tian Y ，Gong S ，Chen X ，Peng T ，Wang A ，Jiang Z ... -  《Drug Design Development and Therapy》

The m(6)A methyltransferase METTL3 promotes hypoxic pulmonary arterial hypertension.

N6-methyladenosine (m6A) is the most prevalent internal chemical RNA modification in mammal mRNAs. Accumulating evidence has shown the critical role of m6A in cardiovascular diseases including cardiac hypertrophy, heart failure, ischemic heart disease, vascular calcification, restenosis, and aortic aneurysm. However, whether m6A participates in the occurrence and development of hypoxic pulmonary hypertension (HPH) remains largely unknown. The present study aims to explore the role of key transferase METTL3, in the development of HPH. Pulmonary artery smooth muscle cells (PASMCs) and hypoxic rat models were used to research the METTL3-mediated m6A in HPH. EdU, transwell and TUNEL were performed to evaluate the proliferation, migration and apoptosis rates. m6A RNA Methylation Quantification Kit and m6A-qPCR were utilized to measure the total m6A level and m6A level of PTEN mRNA. RNA immunoprecipitation was used to detect the interaction between METTL3 and PTEN mRNA. Both METTL3 mRNA and protein were found abnormally upregulated in vivo and in vitro. Furthermore, downregulation of METTL3 attenuated PASMCs proliferation and migration. In addition, m6A binding protein YTHDF2 was found significantly increased in PASMCs under hypoxia. YTHDF2 recognized METTL3 mediated m6A modified PTEN mRNA and promoted the degradation of PTEN. Decreased PTEN led to over-proliferation of PASMCs through activation of PI3K/Akt signaling pathway. METTL3/YTHDF2/PTEN axis exerts a significant role in hypoxia induced PASMCs proliferation, providing a novel therapeutic target for HPH.

Qin Y ，Qiao Y ，Li L ，Luo E ，Wang D ，Yao Y ，Tang C ，Yan G ... -  《-》

Cathepsin S promotes the development of pulmonary arterial hypertension.

Chang CJ ，Hsu HC ，Ho WJ ，Chang GJ ，Pang JS ，Chen WJ ，Huang CC ，Lai YJ ... -  《-》

Calcineurin/NFAT Signaling Modulates Pulmonary Artery Smooth Muscle Cell Proliferation, Migration and Apoptosis in Monocrotaline-Induced Pulmonary Arterial Hypertension Rats.

Pulmonary arterial hypertension (PAH) is a severe and debilitating disease characterized by remodeling of the pulmonary vessels, which is driven by excessive proliferation and migration and apoptosis resistance in pulmonary artery smooth muscle cells (PASMCs). The calcineurin (CaN)/nuclear factor of activated T-cells (NFAT) signaling pathway is the most important downstream signaling pathway of store-operated Ca2+ entry (SOCE), which is increased in PAH. CaN/NFAT has been reported to contribute to abnormal proliferation in chronic hypoxia (CH)-induced PAH. However, the effect of CaN/NFAT signaling on PASMC proliferation, migration and apoptosis in monocrotaline (MCT)-induced PAH remains unclear. PAH rats were established by a single intraperitoneal injection of MCT for 21 days. PASMCs were isolated and cultured in normal and MCT-induced PAH Sprague-Dawley rat. PASMCs were treated with CsA targeting CaN and siRNA targeting NFATc2-4 gene respectively by liposome. We investigated the expression of calcineurin/NFAT signaling by immunofluorescence, qRT-PCR and Western blotting methods. Cell proliferation was monitored using MTS reagent or by assessing proliferating cell nuclear antigen (PCNA) expression. Cell apoptosis was evaluated with an Annexin V - FITC/propidium iodide (PI) apoptosis kit by flow cytometry. PASMC migration was assessed with a Transwell chamber. MCT successfully induced PAH and pulmonary vascular remodeling in rats. CaN phosphatase activity and nuclear translocation of NFATc2-4 were increased in PASMCs derived from MCT-treated rats. In addition, CaNBβ/NFATc2-4 expression was amplified at the mRNA and protein levels. PASMC proliferation and migration were markedly inhibited in a dosedependent manner by cyclosporin A (CsA). Furthermore, siRNA targeting NFATc2 and NFATc4 attenuated the excessive proliferation and migration and apoptosis resistance in PASMCs derived from both CON and MCT-treated rats, while NFATc3 knockdown specifically affected MCT-PASMCs. Our results demonstrate that CaN/NFAT signaling is activated and involved in the modulation of PASMC proliferation, migration and apoptosis in MCT-induced PAH.

He RL ，Wu ZJ ，Liu XR ，Gui LX ，Wang RX ，Lin MJ ... -  《-》