The transcription factor PITX1 cooperates with super-enhancers to regulate the expression of DUSP4 and inhibit pyroptosis in pulmonary artery smooth muscle cells.

Background: Pulmonary hypertension (PH) is a highly fatal pathophysiological syndrome. The group 1 pulmonary arterial hypertension (PAH) is characterized by acute pulmonary vasoconstriction and chronic vascular remodeling caused by hyperplasia and hypertrophy of pulmonary artery smooth muscle cells (PASMCs) and chronic inflammation. Pyroptosis is an inflammatory mode of cell death that is regulated by super-enhancers (SEs) and occurs in the setting of tumors and cardiovascular diseases. However, whether SEs are involved in the pathological process of pyroptosis in PAH and the specific mechanism involved remain unclear.

Methods: Here, we identified the SE target gene DUSP4 via ChIP-seq with an anti-H3K27ac antibody, and bioinformatics predictions revealed that the transcription factor PITX1 can bind to the promoter and SE sequences of DUSP4. The AAV5 vector was used to deliver shRNAs targeting PITX1 and DUSP4 to PASMCs.

Results: PITX1 overexpression reversed the increase in right ventricular systolic pressure and pulmonary vascular remodeling, restored the PAAT/PAVTI ratio in hypoxic pulmonary hypertension (HPH, Group 3 PH) and SuHx PAH (Group 1 PAH) mice, and suppressed pyroptosis in pulmonary vascular cells. However, knockdown of DUSP4 counteracted the effects of PITX1 overexpression. Similar results were obtained in cultured PASMCs. In addition, treatment with the SE inhibitors JQ1 and iBET decreased the transcription of DUSP4 and increased the expression of hypoxia-induced pyroptosis proteins in PASMCs.

Conclusion: We confirmed that PITX1 can promote DUSP4 expression by binding to the DUSP4 promoter and SE to reduce pyroptosis in hypoxic PASMCs, providing new insights into the role of SEs and pyroptosis in pulmonary vascular remodeling and a theoretical basis for the treatment of PAH and related diseases.