title: Temporal and spatial modulation of Rho GTPases during in vitro formation of capillary vascular network. Adherens junctions and myosin light chain as targets of Rac1 and RhoA.
abstract: Endothelial cells (ECs) self-organize into capillary networks when plated on extracellular matrix. In this process, Rho GTPases-mediated cytoskeletal dynamics control cell movement and organization of cell-to-matrix and cell-to-cell contacts. Time course analysis of RhoA and Rac1 activation matches specific morphological aspects of nascent pattern. RhoA-GTP increases early during EC adhesion and accumulates at sites of membrane ruffling. Rac1 is activated later and localizes in lamellipodia and at cell-to-cell contacts of organized cell chains. When ECs stretch and remodel to form capillary structures, RhoA-GTP increases again and associates with stress fibers running along the major cell axis. N17Rac1 and N19RhoA mutants impair pattern formation. Cell-to-cell contacts and myosin light chains (MLC) are targets of Rac1 and RhoA, respectively. N17Rac1 reduces the shift of beta-catenin and vascular endothelial cadherin to Triton X-100-insoluble fraction and impairs beta-catenin distribution at adherens junctions, suggesting that Rac1 controls the dynamics of cadherin-catenin complex with F-actin. During the remodeling phase of network formation, ECs show an intense staining for phosphorylated MLC along the plasma membrane; in contrast, MLC is less phosphorylated and widely diffused in N19RhoA ECs. Both N17Rac1 and N19RhoA have been used to investigate the role of wild type molecules in the main steps characterizing in vitro angiogenesis: (i) cell adhesion to the substrate, (ii) cell movement, and (iii) mechanical remodeling of matrix. N17Rac1 has a striking inhibitory effect on haptotaxis, whereas N19RhoA slightly inhibits EC adhesion and motility but more markedly Matrigel contraction. We conclude that different Rho GTPases control distinct morphogenetic aspects of vascular morphogenesis.
authors.affiliation: Division of Molecular Angiogenesis, Institute for Cancer Research and Treatment (IRCC), Cadiolo, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Cascone
authors.forename: Enrico
authors.initials: E
authors.lastname: Giraudo
authors.forename: Francesca
authors.initials: F
authors.lastname: Caccavari
authors.forename: Lucia
authors.initials: L
authors.lastname: Napione
authors.forename: Elisa
authors.initials: E
authors.lastname: Bertotti
authors.forename: John G
authors.initials: JG
authors.lastname: Collard
authors.forename: Guido
authors.initials: G
authors.lastname: Serini
authors.forename: Federico
authors.initials: F
authors.lastname: Bussolino
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002196:Capillaries / Q000378:metabolism*; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D003094:Collagen / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D003902:Detergents / Q000494:pharmacology; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D005557:Formaldehyde / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007797:Laminin / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D009389:Neovascularization, Pathologic; D017830:Octoxynol / Q000494:pharmacology; D010766:Phosphorylation; D011108:Polymers / Q000494:pharmacology; D011509:Proteoglycans / Q000494:pharmacology; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D051176:beta Catenin; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D003902:Detergents; D004338:Drug Combinations; D007797:Laminin; D011108:Polymers; D011509:Proteoglycans; D015534:Trans-Activators; D051176:beta Catenin; C059485:matrigel; D005557:Formaldehyde; D006160:Guanosine Triphosphate; D017830:Octoxynol; D003094:Collagen; D005982:Glutathione Transferase; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; C003043:paraform