title: The matricellular protein CCN1 controls retinal angiogenesis by targeting VEGF, Src homology 2 domain phosphatase-1 and Notch signaling.
abstract: Physiological angiogenesis depends on the highly coordinated actions of multiple angiogenic regulators. CCN1 is a secreted cysteine-rich and integrin-binding matricellular protein required for proper cardiovascular development. However, our understanding of the cellular origins and activities of this molecule is incomplete. Here, we show that CCN1 is predominantly expressed in angiogenic endothelial cells (ECs) at the leading front of actively growing vessels in the mouse retina. Endothelial deletion of CCN1 in mice using a Cre-Lox system is associated with EC hyperplasia, loss of pericyte coverage and formation of dense retinal vascular networks lacking the normal hierarchical arrangement of arterioles, capillaries and venules. CCN1 is a product of an immediate-early gene that is transcriptionally induced in ECs in response to stimulation by vascular endothelial growth factor (VEGF). We found that CCN1 activity is integrated with VEGF receptor 2 (VEGF-R2) activation and downstream signaling pathways required for tubular network formation. CCN1-integrin binding increased the expression of and association between Src homology 2 domain-containing protein tyrosine phosphatase-1 (SHP-1) and VEGF-R2, which leads to rapid dephosphorylation of VEGF-R2 tyrosine, thus preventing EC hyperproliferation. Predictably, CCN1 further brings receptors/signaling molecules into proximity that are otherwise spatially separated. Furthermore, CCN1 induces integrin-dependent Notch activation in cultured ECs, and its targeted gene inactivation in vivo alters Notch-dependent vascular specification and remodeling, suggesting that functional levels of Notch signaling requires CCN1 activity. These data highlight novel functions of CCN1 as a naturally optimized molecule, fine-controlling key processes in physiological angiogenesis and safeguarding against aberrant angiogenic responses.
authors.affiliation: State University of New York (SUNY) Eye Institute and Department of Cell Biology, Downstate Medical Center, Brooklyn, NY 11203, USA.
authors.forename: Hemabindu
authors.initials: H
authors.lastname: Chintala
authors.affiliation: State University of New York (SUNY) Eye Institute and Department of Cell Biology, Downstate Medical Center, Brooklyn, NY 11203, USA.
authors.forename: Izabela
authors.initials: I
authors.lastname: Krupska
authors.affiliation: State University of New York (SUNY) Eye Institute and Department of Cell Biology, Downstate Medical Center, Brooklyn, NY 11203, USA.
authors.forename: Lulu
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago College of Medicine, Chicago, IL 60607, USA.
authors.forename: Lester
authors.initials: L
authors.lastname: Lau
authors.affiliation: Departments of Ophthalmology and Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Grant
authors.affiliation: State University of New York (SUNY) Eye Institute and Department of Cell Biology, Downstate Medical Center, Brooklyn, NY 11203, USA Department of Ophthalmology, Downstate Medical Center, Brooklyn, NY 11203, USA bchaqour@downstate.edu.
authors.forename: Brahim
authors.initials: B
authors.lastname: Chaqour
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002135:Calcium-Binding Proteins; D002452:Cell Count; D002465:Cell Movement; D049109:Cell Proliferation; D048430:Cell Shape; D055515:Cysteine-Rich Protein 61 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D020868:Gene Silencing; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008565:Membrane Proteins / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic; D009928:Organ Specificity; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000378:metabolism*; D051880:Receptors, Notch / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism*; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D055515:Cysteine-Rich Protein 61; C519665:DLL4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051880:Receptors, Notch; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; C509248:Ptpn6 protein, mouse; D020741:rho GTP-Binding Proteins
keywords: CCN1; Knockout mouse; Matricellular; Retinal angiogenesis; VEGF