title: Coupling of vinculin to F-actin demands Syndecan-4 proteoglycan.
abstract: Syndecans are heparan sulfate proteoglycans characterized as transmembrane receptors that act cooperatively with the cell surface and extracellular matrix proteins. Syn4 knockdown was performed in order to address its role in endothelial cells (EC) behavior. Normal EC and shRNA-Syn4-EC cells were studied comparatively using complementary confocal, super-resolution and non-linear microscopic techniques. Confocal and super-resolution microscopy revealed that Syn4 knockdown alters the level and arrangement of essential proteins for focal adhesion, evidenced by the decoupling of vinculin from F-actin filaments. Furthermore, Syn4 knockdown alters the actin network leading to filopodial protrusions connected by VE-cadherin-rich junction. shRNA-Syn4-EC showed reduced adhesion and increased migration. Also, Syn4 silencing alters cell cycle as well as cell proliferation. Moreover, the ability of EC to form tube-like structures in matrigel is reduced when Syn4 is silenced. Together, the results suggest a mechanism in which Syndecan-4 acts as a central mediator that bridges fibronectin, integrin and intracellular components (actin and vinculin) and once silenced, the cytoskeleton protein network is disrupted. Ultimately, the results highlight Syn4 relevance for balanced cell behavior.
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: R P
authors.initials: RP
authors.lastname: Cavalheiro
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil; Institute of Integrative Biology, Department of Biochemistry, University of Liverpool, Liverpool, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Lima
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: T R
authors.initials: TR
authors.lastname: Jarrouge-Bouças
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: G M
authors.initials: GM
authors.lastname: Viana
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil; Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, SP, Brazil.
authors.forename: C C
authors.initials: CC
authors.lastname: Lopes
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil; University of Houston, College of Optometry, The Ocular Surface Institute (TOSI), Houston, USA.
authors.forename: V J
authors.initials: VJ
authors.lastname: Coulson-Thomas
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil; Grupo Interdisciplinar de Ciências Exatas em Saúde, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: J L
authors.initials: JL
authors.lastname: Dreyfuss
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil; Institute of Integrative Biology, Department of Biochemistry, University of Liverpool, Liverpool, UK.
authors.forename: E A
authors.initials: EA
authors.lastname: Yates
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: I L S
authors.initials: ILS
authors.lastname: Tersariol
authors.affiliation: Disciplina de Biologia Molecular, Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil. Electronic address: hbnader.bioq@epm.br.
authors.forename: H B
authors.initials: HB
authors.lastname: Nader
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D063646:Carcinogenesis / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000473:pathology; D008297:Male; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D011817:Rabbits; D015398:Signal Transduction; D053671:Syndecan-4 / Q000378:metabolism*; D016596:Vinculin / Q000378:metabolism*
chemical_list: D000199:Actins; D053671:Syndecan-4; D016596:Vinculin
keywords: Actin network; Fibronectin; Focal adhesion proteins; Heparan sulfate; Super-resolution microscopy; β1 integrin