title: Proprotein convertase PC5 regulation by PDGF-BB involves PI3-kinase/p70(s6)-kinase activation in vascular smooth muscle cells.
abstract: We have recently demonstrated that furin, PC5, and PC7, members of the subtilisin/kexin-like mammalian proprotein convertases (PCs), are found in rodent aorta. These PCs have been identified to activate several growth factors, adhesion molecules and extracellular matrix compounds by endoproteolytic cleavage. In the present study, we investigated the regulation of PC5 in vascular smooth muscle cells (VSMCs) in vitro and in vivo. Stimulation of rat aortic VSMCs with platelet-derived growth factor (PDGF)-BB (20 ng/mL), angiotensin II (Ang II, 1 micromol/L), or 10% fetal calf serum (FCS) for 48 hours increased DNA synthesis, as assessed by proliferating cell nuclear antigen (PCNA) immunoblotting. PC5 was strongly upregulated by PDGF-BB and 10% FCS (both 8-fold, P<0.05), whereas Ang II had no effect on PC5 protein levels compared with controls. The PCs furin and PC7, which display a comparable subcellular localization and cleavage activity, were found in VSMCs, but their levels did not increase following PDGF-BB, Ang II, or FCS stimulation. Time-course analysis revealed a rapid increase in PC5 levels after 30 minutes of PDGF-stimulation of VSMCs. PDGF-stimulated PC5 induction was inhibited by the PI3-kinase inhibitor wortmannin, and by rapamycin, an inhibitor of mTOR/p70(s6)-kinase (both P<0.05). In contrast, the mitogen-activated protein kinase (MAPK)-pathway inhibitor PD98059 did not inhibit PDGF-stimulated PC5 induction. Immunocytochemistry and in situ hybridization revealed low PC5 protein and mRNA levels in intact rat aorta in vivo. After balloon injury, PC5 protein and mRNA levels were strongly increased in proliferating PCNA-positive VSMCs. The present data demonstrate that PC5 is upregulated during proliferation of VSMCs in vivo and in vitro. We show that PDGF-induced PC5 expression is PI3-kinase/p70(s6)-kinase dependent. Thus, growth factors regulate the proprotein convertase PC5, which may play an important role during VSMC growth.
authors.affiliation: Department of Medicine/Cardiology, Deutsches Herzzentrum Berlin, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Stawowy
authors.forename: Florian
authors.initials: F
authors.lastname: Blaschke
authors.forename: Adam
authors.initials: A
authors.lastname: Kilimnik
authors.forename: Stephan
authors.initials: S
authors.lastname: Goetze
authors.forename: Heike
authors.initials: H
authors.lastname: Kallisch
authors.forename: Michel
authors.initials: M
authors.lastname: Chrétien
authors.forename: Mieczyslaw
authors.initials: M
authors.lastname: Marcinkiewicz
authors.forename: Eckart
authors.initials: E
authors.lastname: Fleck
authors.forename: Kristof
authors.initials: K
authors.lastname: Graf
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000077214:Becaplermin; D002478:Cells, Cultured; D004058:Diffusion; D004789:Enzyme Activation; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D045702:Proprotein Convertase 5; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D019893:Ribosomal Protein S6 Kinases; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000804:Angiotensin II; D000077214:Becaplermin; D019869:Phosphatidylinositol 3-Kinases; D019893:Ribosomal Protein S6 Kinases; D020928:Mitogen-Activated Protein Kinases; D045702:Proprotein Convertase 5; D012697:Serine Endopeptidases; C473807:propeptide convertase 5, rat