Matrix-specific activation of Src and Rho initiates capillary morphogenesis of endothelial cells.
Interstitial collagen I stimulates microvascular endothelial cells to form solid cords that imitate precapillary structures found during angiogenesis. Time-lapse microscopy identified cell retraction and disruption of cell-cell contacts as early critical steps in collagen I-induced capillary morphogenesis. These early stages paralleled collagen I activation of Src kinase and GTPase Rho through beta1 integrins. The Src inhibitor PP2, dominant-negative Src, and Rho inhibitor exoenzyme C3 transferase each inhibited collagen I induction of actin stress fibers that mediate cell retraction and each inhibited capillary morphogenesis. Collagen I also disrupted VE-cadherin from intercellular junctions through a Src-dependent mechanism; both the Src inhibitor PP2 and dominant-negative Src preserved VE-cadherin localization to regions of cell-cell contact. An active Src mutant disrupted VE-cadherin and cell-cell contacts similarly to collagen I. In sharp contrast, laminin-1 did not induce capillary morphogenesis, and laminin-1 did not induce activation of Src or Rho. Rather, laminin-1 induced persistent activation of the GTPase Rac. Thus, these studies identify activation of Src and Rho as key mechanisms by which collagen I provokes capillary morphogenesis of microvascular endothelial cells, and they define marked differences between the functions of collagen I and laminin-1 in regulating endothelial cell morphogenesis.
Division of Cancer Biology and Angiogenesis, Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
Yanqiu
Y
Liu
Donald R
DR
Senger
D036002:ADP Ribose Transferases / Q000494:pharmacology; D019943:Amino Acid Substitution; D000818:Animals; D015703:Antigens, CD; D001905:Botulinum Toxins / Q000494:pharmacology; D015820:Cadherins / Q000378:metabolism; D002196:Capillaries / Q000166:cytology*; D002645:Chickens; D024042:Collagen Type I / Q000502:physiology*; D042783:Endothelial Cells / Q000187:drug effects / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000166:cytology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007365:Intercellular Junctions / Q000187:drug effects; D007797:Laminin / Q000494:pharmacology; D018715:Microscopy, Video; D009024:Morphogenesis / Q000502:physiology; D020125:Mutation, Missense; D017354:Point Mutation; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D011743:Pyrimidines / Q000494:pharmacology; D022502:Stress Fibers / Q000648:ultrastructure; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000502:physiology*; D000099152:Cadherin 5
D036002:ADP Ribose Transferases; D015703:Antigens, CD; D001905:Botulinum Toxins; D015820:Cadherins; D024042:Collagen Type I; D004791:Enzyme Inhibitors; D007797:Laminin; D016392:Proto-Oncogene Proteins pp60(c-src); D011743:Pyrimidines; D020742:rhoA GTP-Binding Protein; D000099152:Cadherin 5; C412373:AG 1879; C121346:laminin 1; C063007:exoenzyme C3, Clostridium botulinum