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Cancer Cell death Cell cycle Cytoskeleton Exo/endocytosis Differentiation Division Organelles Signalling Stem cells Trafficking
Cell Biology International (1996) 20, 471–479 (Printed in Great Britain)
INTEGRIN SYNTHESIS AND UTILIZATION IN CULTURED HUMAN OSTEOBLASTS
M. PISTONEa, C. SANGUINETIa, A. FEDERICIb, F. SANGUINETIb, P. DEFILIPPIb, F. SANTOLINIbc, G. QUERZÉd, P.C. MARCHISIOe and P. MANDUCAaf1
aGenetica, Istituto di Fisiologia, University of Genova, Italy
bDipartimento di Scienze Motorie, University of Genova, Italy
cDipartimento di Genetica, Biologia, Chimica Medica, University of Torino, Italy
eDipartimento di Scienze Biomediche e Oncologia Umana, University of Torino, Italy
dLaboratorio di Biologia Cellulare, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy


Abstract

This study describes the adhesion of human osteoblasts, culturedin vitro, to proteins of the extracellular matrix, the biosynthesis of integrins, their topography and organization in focal contacts. The adhesion of osteoblasts to laminin, type I collagen, vitronectin and fibronectin was 77–100%, in 2h and at 55nmsubstrata concentration, and it was accompained by spreading of the cells. Adhesion to fibronectin (FN), laminin (LN) and type I collagen (COL) was inhibited by antibodies to the β1 integrin and antibodies to the α5 chain affected adhesion only to fibronectin. Using a panel of polyclonal antibodies against α2, α3, α5, αv, β1 andβ3 integrins we detected synthesis of α3β1, α5β1, αvβ3, and an αvβ1-like dimer by immunoprecipitation of metabolically labelled cell lysates. Studies of immunolocalization demonstrated the presence of the same integrins identified in lysates, plus α4, α1 and β5 subunits. In cells adhering in the presence of serum we showed organization of β3 and αv integrins in focal contacts. In cells adhering to fibronectin α5 and β1 integrins were localized in focal contacts. In cells spread on laminin or type I collagen none of the integrins investigated was localized in focal contacts.


Key words: human osteoblasts, integrin biosynthesis, integrin localization, adhesion to ECM.

f1To whom correspondence should be addressed.


doi:10.1006/cbir.1996.0062


ISSN Print: 1065-6995
ISSN Electronic: 1095-8355
Published by Portland Press Limited on behalf of the International Federation for Cell Biology (IFCB)