AIP4 inhibits NPE pulmonary microvascular endothelial cell apoptosis and barrier failure via regulation of TRPV4 subcellular location in vitro.

Background: Neurogenic pulmonary edema (NPE) is a severe complication of subarachnoid hemorrhage that aggravates pulmonary microvascular endothelial barrier dysfunction. In this study, we aimed to explore the role of TRPV4 in NPE progression. Method: An NPE rat model was established through the endovascular perforation technique for the collection of NPE serum and pulmonary microvascular endothelial cells (PMVECs). PMVECs were incubated with NPE serum, the FITC-dextran extravasation was applied for permeability analysis, and the cell apoptosis was measured by flow cytometry. TRPV4 subcellular localization was detected by immunofluorescent staining. Finally, we performed the co-immunoprecipitation for AIP4 and TRPV4 binding association analysis. Results: NPE serum incubation promoted PMVECs apoptosis and barrier dysfunction. The TRPV4 level and p38 signaling were activated in PMVECs treated with NPE serum. However, these phenomena were reversed by TRPV4 inhibition. AIP4 promoted TRPV4 ubiquitination and led to the transfer of TRPV4 from the cell membrane to the cytoplasm. Overall, AIP4 ubiquitinated TRPV4, leading to p38 signaling inhibition, thereby blocking PMVECs apoptosis and barrier dysfunction under the NPE serum. Conclusion: TRPV4 is ubiquitinated by API4 and transferred to the cytoplasm, enhancing p38 signaling to promote PMVECs apoptosis and barrier dysfunction under NPE serum conditions.