Critical role of VGLL4 in the regulation of chronic normobaric hypoxia‐induced pulmonary hypertension in mice

Pulmonary hypertension (PH), a rare but deadly cardiopulmonary disorder, is characterized by extensive remodeling of pulmonary arteries resulting from enhancement of pulmonary artery smooth muscle cell proliferation and suppressed apoptosis; however, the underlying pathophysiological mechanisms remain largely unknown. Recently, epigenetics has gained increasing prominence in the development of PH. We aimed to investigate the role of vestigial-like family member 4 (VGLL4) in chronic normobaric hypoxia (CNH)-induced PH and to address whether it is associated with epigenetic regulation. The rodent model of PH was established by CNH treatment (10% O2, 23 hours/day). Western blot, quantitative reverse transcription polymerase chain reaction, immunofluorescence, immunoprecipitation, and adeno-associated virus tests were performed to explore the potential mechanisms involved in CNH-induced PH in mice. VGLL4 expression was upregulated and correlated with CNH in PH mouse lung tissues in a time-dependent manner. VGLL4 colocalized with α-smooth muscle actin in cultured pulmonary arterial smooth muscle cells (PASMCs), and VGLL4 immunoactivity was increased in PASMCs following hypoxia exposure in vitro. VGLL4 knockdown attenuated CNH-induced PH and pulmonary artery remodeling by blunting signal transducer and activator of transcription 3 (STAT3) signaling; conversely, VGLL4 overexpression exacerbated the development of PH. CNH enhanced the acetylation of VGLL4 and increased the interaction of ac-H3K9/VGLL4 and ac-H3K9/STAT3 in the lung tissues, and levels of ac-H3K9, p-STAT3/STAT3, and proliferation-associated protein levels were markedly up-regulated, whereas apoptosis-related protein levels were significantly downregulated, in the lung tissues of mice with CNH-induced PH. Notably, abrogation of VGLL4 acetylation reversed CNH-induced PH and pulmonary artery remodeling and suppressed STAT3 signaling. Finally, STAT3 knockdown alleviated CNH-induced PH. In conclusion, VGLL4 acetylation upregulation could contribute to CNH-induced PH and pulmonary artery remodeling via STAT3 signaling, and abrogation of VGLL4 acetylation reversed CNH-induced PH. Pharmacological or genetic deletion of VGLL4 might be a potential target for therapeutic interventions in CNH-induced PH.