title: Sildenafil inhibits hypoxia-induced transient receptor potential canonical protein expression in pulmonary arterial smooth muscle via cGMP-PKG-PPARγ axis.
abstract: Transient receptor potential canonical (TRPC) proteins play important roles in chronically hypoxic pulmonary hypertension (CHPH). Previous results indicated that sildenafil inhibited TRPC1 and TRPC6 expression in rat distal pulmonary arteries (PAs). However, the underlying mechanisms remain unknown. We undertook this study to investigate the downstream signaling of sildenafil's regulation on TRPC1 and TRPC6 expression in pulmonary arterial smooth muscle cells (PASMCs). Hypoxia-exposed rats (10% O2 for 21 d) and rat distal PASMCs (4% O2 for 60 h) were taken as models to mimic CHPH. Real-time PCR, Western blotting, and Fura-2-based fluorescent microscopy were performed for mRNA, protein, and Ca(2+) measurements, respectively. The cellular cyclic guanosine monophosphate (cGMP) analogue 8-(4-chlorophenylthio)-guanosine 3',5'-cyclic monophosphate sodium salt (CPT-cGMP) (100 μM) inhibited TRPC1 and TRPC6 expression, store-operated Ca(2+) entry (SOCE), and the proliferation and migration of PASMCs exposed to prolonged hypoxia. The inhibition of CPT-cGMP on TRPC1 and TRPC6 expression in PASMCs was relieved by either the inhibition or knockdown of cGMP-dependent protein kinase (PKG) and peroxisome proliferator-activated receptor γ (PPARγ) expression. Under hypoxic conditions, CPT-cGMP increased PPARγ expression. This increase was abolished by the PKG antagonists Rp8 or KT5823. PPARγ agonist GW1929 significantly decreased TRPC1 and TRPC6 expression in PASMCs. Moreover, hypoxia exposure decreased, whereas sildenafil treatment increased, PKG and PPARγ expression in PASMCs ex vivo, and in rat distal PAs in vivo. The suppressive effects of sildenafil on TRPC1 and TRPC6 in rat distal PAs and on the hemodynamic parameters of CHPH were inhibited by treatment with the PPARγ antagonist T0070907. We conclude that sildenafil inhibits TRPC1 and TRPC6 expression in PASMCs via cGMP-PKG-PPARγ-dependent signaling during CHPH.
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Lai
authors.forename: Hua
authors.initials: H
authors.lastname: Jiang
authors.forename: Yajie
authors.initials: Y
authors.lastname: Zhang
authors.forename: Nanshan
authors.initials: N
authors.lastname: Zhong
authors.forename: Pixin
authors.initials: P
authors.lastname: Ran
authors.forename: Wenju
authors.initials: W
authors.lastname: Lu
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001577:Benzophenones / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D006152:Cyclic GMP / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D000860:Hypoxia / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000378:metabolism*; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011651:Pulmonary Artery / Q000378:metabolism* / Q000473:pathology; D011687:Purines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology*; D050052:TRPC Cation Channels / Q000096:biosynthesis*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D001549:Benzamides; D001577:Benzophenones; D002227:Carbazoles; D047495:PPAR gamma; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011687:Purines; D011725:Pyridines; D013450:Sulfones; C458508:T 0070907; D050052:TRPC Cation Channels; C492145:Trpc6 protein, rat; C096351:transient receptor potential cation channel, subfamily C, member 1; C073601:KT 5823; D014443:Tyrosine; D000068677:Sildenafil Citrate; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP; C120099:GW 1929