title: Proprotein convertases play an important role in regulating PKGI endoproteolytic cleavage and nuclear transport.
abstract: Nitric oxide and cGMP modulate vascular smooth muscle cell (SMC) phenotype by regulating cell differentiation and proliferation. Recent studies suggest that cGMP-dependent protein kinase I (PKGI) cleavage and the nuclear translocation of a constitutively active kinase fragment, PKGIγ, are required for nuclear cGMP signaling in SMC. However, the mechanisms that control PKGI proteolysis are unknown. Inspection of the amino acid sequence of a PKGI cleavage site that yields PKGIγ and a protease database revealed a putative minimum consensus sequence for proprotein convertases (PCs). Therefore we investigated the role of PCs in regulating PKGI proteolysis. We observed that overexpression of PCs, furin and PC5, but not PC7, which are all expressed in SMC, increase PKGI cleavage in a dose-dependent manner in human embryonic kidney (HEK) 293 cells. Moreover, furin-induced proteolysis of mutant PKGI, in which alanines were substituted into the putative PC consensus sequence, was decreased in these cells. In addition, overexpression of furin increased PKGI proteolysis in LoVo cells, which is an adenocarcinoma cell line expressing defective furin without PC activity. Also, expression of α1-PDX, an engineered serpin-like PC inhibitor, reduced PC activity and decreased PKGI proteolysis in HEK293 cells. Last, treatment of low-passage rat aortic SMC with membrane-permeable PC inhibitor peptides decreased cGMP-stimulated nuclear PKGIγ translocation. These data indicate for the first time that PCs have a role in regulating PKGI proteolysis and the nuclear localization of its active cleavage product, which are important for cGMP-mediated SMC phenotype.
authors.affiliation: Cardiovascular Research Center of the General Medical Services, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Shin
authors.initials: S
authors.lastname: Kato
authors.forename: Ruiguang
authors.initials: R
authors.lastname: Zhang
authors.forename: Jesse D
authors.initials: JD
authors.lastname: Roberts
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology* / Q000235:genetics; D006152:Cyclic GMP / Q000235:genetics / Q000378:metabolism; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000378:metabolism*; D045683:Furin / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000201:enzymology; D045702:Proprotein Convertase 5 / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D051381:Rats; D013381:Subtilisins / Q000235:genetics / Q000378:metabolism
chemical_list: D062965:Cyclic GMP-Dependent Protein Kinase Type I; C099101:PCSK7 protein, human; C490930:Pcsk7 protein, mouse; C490931:Pcsk7 protein, rat; D045702:Proprotein Convertase 5; D013381:Subtilisins; C468731:FURIN protein, human; D045683:Furin; D006152:Cyclic GMP
keywords: guanosine 3′,5′-cyclic monophosphate-dependent protein kinase I; nitric oxide and guanosine 3′,5′-cyclic monophosphate signaling; proprotein convertase