title: Transforming growth factor beta stimulates fibroblast-collagen matrix contraction by different mechanisms in mechanically loaded and unloaded matrices.
abstract: Studies were carried out to test the idea that transforming growth factor beta (TGFbeta) stimulated fibroblast contraction of collagen matrices by different mechanisms depending on mechanical loading on the cells and matrix. Under mechanically unloaded conditions (floating matrices), TGFbeta stimulated contraction directly as an agonist and indirectly by preactivating cells to express the myofibroblast phenotype. Increased contraction of floating matrices by preactivated cells appeared to result in part from an autocrine mechanism. Under mechanically loaded conditions (stressed matrices), TGFbeta had no direct agonist effect on contraction. Fibroblasts preactivated to become myofibroblasts showed increased ability to transfer tension to stressed matrices, and tension persisted even after the cells' actin cytoskeleton was disrupted. Our findings are consistent with the idea that fibroblasts activated to become myofibroblasts in vitro have increased contractile activity and indicate that multiple mechanisms that differ depending on mechanical loading on the cells and matrix are involved.
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9039, USA. frederick.grinnell@utsouthwestern.edu
authors.forename: Frederick
authors.initials: F
authors.lastname: Grinnell
authors.forename: Chin-Han
authors.initials: CH
authors.lastname: Ho
mesh_terms: D000199:Actins / Q000096:biosynthesis; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism*; D015638:Cytochalasin D / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D000199:Actins; D008246:Lysophospholipids; D019384:Nucleic Acid Synthesis Inhibitors; D016212:Transforming Growth Factor beta; D015638:Cytochalasin D; D003094:Collagen