SP1/ADAM10/DRP1 axis links intercellular communication between smooth muscle cells and endothelial cells under hypoxia pulmonary hypertension.

BACKGROUND

Crosstalk between endothelial cells (ECs) and smooth muscle cells (SMCs) contributes to the progression of hypoxia pulmonary hypertension (HPH).

OBJECTIVE

In this study, we investigated whether the SP1/ADAM10/DRP1 and ADAM10-PI3K-AKT-mTOR axis mediate the crosstalk between ECs and SMCs.

METHODS AND RESULTS

The expression of ADAM10 increased in hypoxia-treated rats and ECs. Furthermore, the knockdown of ADAM10 alleviated HPH in rats and the malignant phenotype of hypoxia ECs. ADAM10 expression upregulated in the conditioned medium of hypoxia ECs. Conditioned medium was separated and added to the SMC culture system. Adding SMCs to a conditioned medium containing hypoxia-induced ECs promoted proliferation and decreased the apoptosis of SMCs. When SMCs were treated with a conditioned medium from ECs in which ADAM10 expression was knocked down, we found that the effects of the conditioned medium on the proliferation and apoptosis of SMCs were reduced. The protein levels of DRP1, PI3K, AKT, and mTOR decreased in SMCs treated with a conditioned medium of ECs in which ADAM10 was knocked down. After overexpressing ADAM10 in ECs, the medium was collected and added into the SMC culture system containing Mdivi-1 (DRP1 inhibitor) or LY294002 (PI3K inhibitor), and the SMCs showed reduced proliferation and increased apoptosis. SP1 was predicted based on the promoter regions of ADAM10 using the JASPAR database. The downregulation of SP1 decreases ADAM10 expression.

CONCLUSION

SP1 increases the secretion and levels of ADAM10 in hypoxia ECs. ADAM10 released by ECs regulates the hypoxia-induced malignant phenotype of SMCs via the DRP1 and PI3K/AKT/mTOR signaling pathways.