title: Pro-angiogenic activities of CYR61 (CCN1) mediated through integrins alphavbeta3 and alpha6beta1 in human umbilical vein endothelial cells.
abstract: CYR61 (CCN1) is an extracellular matrix-associated protein of the CCN family, which also includes CTGF (CCN2), NOV (CCN3), WISP-1 (CCN4), WISP-2 (CCN5), and WISP-3 (CCN6). Purified CYR61 induces neovascularization in corneal implants, and Cyr61-null mice suffer embryonic death due to vascular defects, thus establishing that CYR61 is an important regulator of angiogenesis. Aberrant expression of Cyr61 is associated with breast cancer, wound healing, and vascular diseases such as atherosclerosis and restenosis. In culture, CYR61 functions through integrin-mediated pathways to promote cell adhesion, migration, and proliferation. Here we show that CYR61 can also promote cell survival and tubule formation in human umbilical vein endothelial cells. Furthermore, we have dissected the integrin receptor requirements of CYR61 with respect to its pro-angiogenic activities. Thus, CYR61-induced cell adhesion and tubule formation occur through interaction with integrin alpha(6)beta(1) in early passage endothelial cells in which integrins have not been activated. By contrast, in endothelial cells in which integrins are activated by phorbol ester or vascular endothelial growth factor, CYR61-promoted cell adhesion, migration, survival, growth factor-induced mitogenesis, and endothelial tubule formation are all mediated through integrin alpha(v)beta(3). These findings indicate that CYR61 is an activation-dependent ligand of integrin alpha(v)beta(3) and an activation-independent ligand of integrin alpha(6)beta(1) and that these integrins differentially mediate the pro-angiogenic activities of CYR61. These findings help to define the mechanisms by which CYR61 acts as an angiogenic regulator, provide a molecular interpretation for the loss of vascular integrity and increased apoptosis of vascular cells in Cyr61-null mice, and underscore the importance of CYR61 in the development and homeostasis of the vascular system.
mesh_terms: D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D055515:Cysteine-Rich Protein 61; D004261:DNA Replication / Q000502:physiology; D016228:Endothelial Growth Factors / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000502:physiology*; D039121:Integrin alpha6beta1 / Q000502:physiology*; D039302:Integrin alphaVbeta3 / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology*; D008222:Lymphokines / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: C501848:CCN1 protein, human; D055515:Cysteine-Rich Protein 61; D016228:Endothelial Growth Factors; D017874:Immediate-Early Proteins; D039121:Integrin alpha6beta1; D039302:Integrin alphaVbeta3; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors