beta(3)A-integrin downregulates the urokinase-type plasminogen activator receptor (u-PAR) through a PEA3/ets transcriptional silencing element in the u-PAR promoter.
Migration of cells requires interactions with the extracellular matrix mediated, in part, by integrins, proteases, and their receptors. Previous studies have shown that beta(3)-integrin interacts with the urokinase-type plasminogen activator receptor (u-PAR) at the cell surface. Since integrins mediate signaling into the cell, the current study was undertaken to determine if in addition beta(3)-integrin regulates u-PAR expression. Overexpression of beta(3)-integrin in CHO cells, which are avid expressers of the receptor, downregulated u-PAR protein and mRNA expression. The u-PAR promoter (-1,469 bp) that is normally constitutively active in CHO cells was downregulated by induced beta(3)-integrin expression. A region between -398 and -197 bp of the u-PAR promoter was critical for beta(3)-integrin-induced downregulation of u-PAR promoter activity. Deletion of the PEA3/ets motif at -248 bp substantially impaired the ability of beta(3)-integrin to downregulate the u-PAR promoter, suggesting that the PEA3/ets site acts as a silencing element. An expression vector encoding the transcription factor PEA3 caused inhibition of the wild-type but not the PEA3/ets-deleted u-PAR promoter. The PEA3/ets site bound nuclear factors from CHO cells specifically, but binding was enhanced when beta(3)-integrin was overexpressed. A PEA3 antibody inhibited DNA-protein complex formation, indicating the presence of PEA3. Downregulation of the u-PAR promoter was achieved by the beta(3)A-integrin isoform but not by other beta(3)-integrin isoforms and required the cytoplasmic membrane NITY(759) motif. Moreover, overexpression of the short but not the long isoform of the beta(3)-integrin adapter protein beta(3)-endonexin blocked u-PAR promoter activity through the PEA3/ets binding site. Thus, besides the physical interaction of beta(3)-integrin and u-PAR at the cell surface, beta(3) signaling is implicated in the regulation of u-PAR gene transcription, suggesting a mutual regulation of adhesion and proteolysis receptors.
Department of Obstetrics and Gynecology, Deutsches Herzzentrum, Technische Universität München, Klinikum rechts der Isar, D-81675 Munich, Germany.
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S
Hapke
M
M
Gawaz
K
K
Dehne
J
J
Köhler
J F
JF
Marshall
H
H
Graeff
M
M
Schmitt
U
U
Reuning
E
E
Lengyel
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D039661:Integrin beta3; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010980:Platelet Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic
D015703:Antigens, CD; C403295:ITGB3BP protein, human; D039661:Integrin beta3; D009687:Nuclear Proteins; D010980:Platelet Membrane Glycoproteins; D011506:Proteins; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins