Protease‐activated receptor 1 expressed in the human corpus cavernosum induces phosphorylation of endothelial nitric oxide synthase at threonine 495

Abstract

Protease‐activated receptor 1 (PAR1) can induce phosphorylation of endothelial nitric oxide synthase (eNOS) at site threonine 495 to inhibit production of nitric oxide. The objective of this project is to elucidate whether PAR1 is a potential therapeutic target for improving availability of nitric oxide in patients with erectile dysfunction and related vascular diseases. PAR1 has not been shown to be expressed in the penile endothelium, however. I hypothesize that PAR1 is expressed in the endothelium of the corpora cavernosa of the penis and, once activated, leads to significant phosphorylation of eNOS‐Thr495. Human corpus cavernosum endothelial cells (HCCECs) were lysed and probed for PAR1 expression using western blot and immunocytochemistry. The cells were then stimulated with thrombin or TFLLR, a PAR1 agonist, and phosphorylation of eNOS was examined by western blot and enzyme‐linked immunosorbent assay. Expression of PAR1 was detected in the HCCECs. Treatment with thrombin and TFLLR induced concentration and time dependent phosphorylation of eNOS‐Thr495. This study shows that PAR1 is expressed in the penile endothelium. Future studies include analyzing any differences in expression or functionality of PAR1 in HCCECs from males with erectile dysfunction.This project was supported, in part, by National Institute of General Medical Sciences (NIGMS) Grant 5SC3GM086336‐02.