title: C-type natriuretic peptide decreases soluble guanylate cyclase levels by activating the proteasome pathway.
abstract: Natriuretic peptides (NP) activate particulate guanylate cyclase (pGC) and nitric oxide (NO) activates soluble guanylate cyclase (sGC). Both guanylate cyclases catalyse the formation of the same second messenger, cyclic guanosine 3',5'-monophosphate (cGMP), which activates the cGMP-dependent protein kinases (PKG). PKG then starts a signalling cascade that mediates many cardiovascular and renal effects, such as smooth muscle relaxation and diuresis. Many cell types possess both sGC and pGC. Because both GC-cGMP systems play complementary roles, an interaction between the two pathways might represent an important physiological control mechanism. In this report we demonstrate an interaction between the two pathways. C-type natriuretic peptide (CNP) decreased the beta-subunit of sGC (sGC-beta) steady-state protein levels and enzymatic activity in cultured human mesangial cells (HMC) in a time- and dose-dependent manner. This down-regulation was not dependent on changes in sGC-beta mRNA levels. Treatment of the cells with the stable cGMP analogue 8-Br-cGMP or the phosphodiesterase type-5 inhibitor Zaprinast produced the same down-regulatory effect. Inhibition of PKG or proteasome activity prevented the CNP-induced reduction of sGC-beta protein levels and activity. Taken together, these results demonstrate that pGC activation induces a post-transductional down-regulation of sGC by a mechanism involving PKG and the proteasome pathway.
authors.affiliation: Department of Physiology, Alcalá de Henares University, Madrid, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: de Frutos
authors.forename: Marta
authors.initials: M
authors.lastname: Saura
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Rivero-Vilches
authors.forename: D
authors.initials: D
authors.lastname: Rodriguez-Puyol
authors.forename: M
authors.initials: M
authors.lastname: Rodriguez-Puyol
mesh_terms: D002478:Cells, Cultured; D006152:Cyclic GMP; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D025461:Feedback, Physiological; D005920:Glomerular Mesangium / Q000166:cytology; D006162:Guanylate Cyclase / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D009097:Multienzyme Complexes / Q000378:metabolism*; D020098:Natriuretic Peptide, C-Type / Q000494:pharmacology*; D009569:Nitric Oxide / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger / Q000032:analysis; D012995:Solubility
chemical_list: D009097:Multienzyme Complexes; D012333:RNA, Messenger; D020098:Natriuretic Peptide, C-Type; D009569:Nitric Oxide; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D006162:Guanylate Cyclase; D006152:Cyclic GMP