title: Platelet-derived growth factor-BB-mediated glycosaminoglycan synthesis is transduced through Akt.
abstract: Previously we have demonstrated that the phosphoinositide 3-kinase (PI-3K) signal-transduction pathway mediates platelet-derived growth factor (PDGF)-BB-induced glycosaminoglycan (GAG) synthesis in fetal lung fibroblasts. In the present study we further investigated the signal-transduction pathway(s) that results in PDGF-BB-induced GAG synthesis. Over-expression of a soluble PDGF beta-receptor as well as a mutated form of the beta-receptor, unable to bind PI-3K, diminished GAG synthesis in fetal lung fibroblasts subsequent to PDGF-BB stimulation. The PI-3K inhibitor wortmannin blocked PDGF-BB-induced Akt activity as well as significantly diminishing PDGF-BB-mediated GAG synthesis. Expression of dominant-negative PI-3K also abrogated Akt activity and GAG synthesis. Furthermore, expression of dominant-negative Akt abrogated endogenous Akt activity, Rab3D phosphorylation and GAG synthesis, whereas expression of constitutively activated Akt stimulated Rab3D phosphorylation and GAG synthesis in the absence of PDGF-BB. Over-expression of wild-type PTEN (phosphatase and tensin homologue deleted in chromosome 10) inhibited Akt activity and concomitantly attenuated GAG synthesis in fibroblasts stimulated with PDGF-BB. These data suggest that Akt is an integral protein involved in PDGF-BB-mediated GAG regulation in fetal lung fibroblasts.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada M5G 1L5.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Cartel
authors.forename: Jinxia
authors.initials: J
authors.lastname: Wang
authors.forename: Martin
authors.initials: M
authors.lastname: Post
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000077214:Becaplermin; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D005799:Genes, Dominant; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D015151:Immunoblotting; D008168:Lung / Q000196:embryology; D008297:Male; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D000077191:Wortmannin; D020692:rab3 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000730:Androstadienes; D000077214:Becaplermin; D004791:Enzyme Inhibitors; D006025:Glycosaminoglycans; D019869:Phosphatidylinositol 3-Kinases; D010982:Platelet-Derived Growth Factor; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D020574:Proto-Oncogene Proteins c-sis; D014443:Tyrosine; D000077191:Wortmannin; D020692:rab3 GTP-Binding Proteins; C494920:Akt1 protein, rat; C492133:Rab3d protein, rat