Effect of laminin-1 on intestinal cell differentiation involves inhibition of nuclear nucleolin.
Intestinal epithelial cells are characterized by continuous renewal and differentiation events, which may be influenced by the basement membrane, and in particular laminins, which are major components of this specialized extracellular matrix. The function and signaling pathways of laminins in these processes are still poorly documented. In this study, we investigated the possible role and the subcellular localization of nucleolin, a nuclear shuttling protein, in relation to differentiation of human intestinal epithelial Caco2/TC7 cells triggered by exogenous laminin-1. Immunofluorescence and Western blot analysis indicated that laminin-1 induced early differentiation of the cells concomitantly to a decrease in nuclear nucleolin and its a cell surface location. We also showed that both effects of laminin-1 on Caco2/TC7 cells--induction of the differentiation marker sucrase-isomaltase and redistribution of nucleolin--could be mediated by a beta1-integrin dependent cascade that implicated activation of the p38 MAPK pathway. In addition, knock-down of nucleolin expression by the small interfering RNA strategy mimicked the effect of laminin-1 as it resulted in the induction of cell polarization and differentiation. Thus, our study suggests that changes in the subcellular distribution and expression level of nucleolin play an important role in intestinal cell differentiation and relay the signaling pathway induced by laminin-1.
Turck
Natacha
N
Inserm, U682, Strasbourg F-67200 France; Univ. Louis Pasteur, Strasbourg, F-67200 France.
Lefebvre
Olivier
O
Gross
Isabelle
I
Gendry
Patrick
P
Kedinger
Michèle
M
Simon-Assmann
Patricia
P
Launay
Jean-François
JF
D001483:Base Sequence; D001692:Biological Transport; D018938:Caco-2 Cells; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D039641:Integrin beta Chains / Q000378:metabolism; D007797:Laminin / Q000378:metabolism / Q000494:pharmacology* / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism*; D000097796:Nucleolin
D039641:Integrin beta Chains; D007797:Laminin; D020929:Mitogen-Activated Protein Kinase Kinases; D009687:Nuclear Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D000097796:Nucleolin; C121346:laminin 1; C119013:laminin 10