title: Recombinant human platelet-derived growth factor and transforming growth factor-beta mediated contraction of human dermal fibroblast populated lattices is inhibited by Rho/GTPase inhibitor but does not require phosphatidylinositol-3' kinase.
abstract: Matrix reorganization and tissue contraction are essential for wound healing. However, the intracellular signals that mediate these processes are largely unknown. We investigated cytokine-induced signaling and its potential role in contraction of adult human dermal fibroblast populated collagen lattices. The results document that recombinant human platelet-derived growth factor-BB and transforming growth factor-1 individually stimulate contraction of fibroblast populated collagen lattices, while a combination of the two cytokines leads to increased contraction. Although recombinant human platelet-derived growth factor-BB promoted collagen contraction, it failed to stimulate phosphatidylinositol-3' kinase in the human dermal fibroblasts. An inhibitor for phosphatidylinositol 3' kinase, wortmannin, had no effect on the cytokine-mediated collagen contraction. In addition, this failed activation of phosphatidylinositol 3' kinase is consistent with absence of tyrosine phosphorylation of the platelet-derived growth factor receptor when the cells are in a collagen matrix. In contrast, tyrosine phosphorylation of the platelet-derived growth factor receptor was readily detected in the dermal fibroblasts in monolayers. We also probed the potential role of Rho/GTPase in the cytokine-mediated contraction of fibroblast populated collagen lattices. Toxin B from Clostridium difficile at picomolar concentrations blocked both recombinant human platelet-derived growth factor and transforming growth factor-5 induced contraction. Further, this inhibition was correlated with the inhibition of cell spreading in collagen, which suggests the formation of actin fibers inside the cells is essential for cytokine-mediated contraction of fibroblast populated collagen lattices. Taken together, these results imply that Rho/GTPase signaling but not phosphoinositol-3' kinase is involved in the cytokine-mediated contraction of fibroblasts populated collagen lattice. These findings suggest a potential mechanism for these signaling components during human wound contraction.
authors.affiliation: Division of Plastic and Reconstructive Surgery, University of Southern California, Los Angeles, CA 90033, USA.
authors.forename: Yuan-Ping
authors.initials: YP
authors.lastname: Han
authors.forename: Yih-Dar
authors.initials: YD
authors.lastname: Nien
authors.forename: Warren L
authors.initials: WL
authors.lastname: Garner
mesh_terms: D000199:Actins / Q000378:metabolism; D000077214:Becaplermin; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D005347:Fibroblasts / Q000502:physiology*; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D014945:Wound Healing / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D000199:Actins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D000077214:Becaplermin; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D020741:rho GTP-Binding Proteins