title: The regulation of MacMARCKS expression by integrin beta3.
abstract: Integrin-mediated adhesion regulates multiple signaling pathways. Our group previously showed that ectopic expression of different integrin beta-subunits in the neuroepithelial cell line GE11, has distinct effects on cell morphology, actin cytoskeletal organization, and on focal contact distribution. In this report we have investigated changes in gene transcription levels resulting from overexpression of the integrin beta3 subunit. We found that beta3 overexpression leads to the transcriptional downregulation of MARCKS related protein (MRP) resulting in a decreased expression of the MRP protein. Furthermore, we show that the Ras/MAPK pathway controls the basal level of MRP expression but beta3 overexpression bypasses this pathway downstream of ERK to downregulate MRP. Further studies indicate that a region of the cytoplasmic tail of beta3 containing part of the NITY motif is responsible for increased cell spreading and MRP downregulation. However, MRP overexpression failed to inhibit the beta3-induced increase in cell spreading while the knock down of MRP expression in GE11 cells did not increase cell spreading. We suggest that the downregulation of MRP by beta3 is not required for increased cell spreading but instead that MRP downregulation is a secondary effect of increased cell spreading.
authors.affiliation: Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands.
authors.forename: Iman
authors.initials: I
authors.lastname: van den Bout
authors.forename: Hoa H
authors.initials: HH
authors.lastname: Truong
authors.forename: Stephan
authors.initials: S
authors.lastname: Huveneers
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kuikman
authors.forename: Erik H J
authors.initials: EH
authors.lastname: Danen
authors.forename: Arnoud
authors.initials: A
authors.lastname: Sonnenberg
mesh_terms: D000818:Animals; D002148:Calmodulin-Binding Proteins; D002460:Cell Line; D002465:Cell Movement; D003593:Cytoplasm / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006801:Humans; D039482:Integrin alpha5 / Q000378:metabolism; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D039661:Integrin beta3 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008840:Microfilament Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate
chemical_list: D002148:Calmodulin-Binding Proteins; D039482:Integrin alpha5; D039302:Integrin alphaVbeta3; D039661:Integrin beta3; D047908:Intracellular Signaling Peptides and Proteins; C000619710:MARCKS protein, human; C070177:MARCKSL1 protein, human; C000619711:Marcks protein, mouse; C512945:Marcksl1 protein, mouse; D008565:Membrane Proteins; D008840:Microfilament Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate