Promotor hypomethylation mediated upregulation of VCAN targets Twist1 to promote EndMT in hypoxia-induced pulmonary hypertension

<bold>Background:</bold> Hypoxia-induced pulmonary hypertension (HPH) is a severe vascular disorder that is characterized by the involvement of endothelial-to-mesenchymal transition (EndMT) in its pathogenesis. Our previous research has suggested that the gene Versican (VCAN), may have a crucial role in the development of HPH. However, the exact function of VCAN in HPH requires further investigation. <bold>Methods:</bold> The expression of VCAN and markers of EndMT was assessed using western blot, immunohistochemistry, and immunofluorescence. Vascular remodeling and right ventricular hypertrophy in HPH patients and mice were evaluated through H&E staining, Masson's staining, and hemodynamic measurements. To confirm the regulatory role of VCAN, knockdown experiments were conducted in mouse and cell models. The interaction between VCAN and Twist1 was validated using co-immunoprecipitation (Co-IP). The DNA methylation level of VCAN was examined using methylation-specific PCR (MSP). <bold>Results:</bold> EndMT was observed in HPH patients, HPH mouse models and hypoxia-treated HPAECs, accompanied by a significant increase of VCAN. Endothelium-specific knockdown of VCAN reversed HPH progression and effectively prevented EndMT in mouse models and HPAECs. We further confirmed that VCAN participated in EndMT by targeting the key transcription factor Twist1. Additionally, the upregulation of VCAN may be attributed to promoter hypomethylation, which was mediated by reduced DNA methyltransferases activity under hypoxic conditions. <bold>Conclusions:</bold> This study firstly provides the initial evidence showcasing the role of promoter hypomethylation-mediated VCAN upregulation in promoting EndMT by targeting Twist1, which facilitates vascular remodeling and the progression of HPH.