title: Regulation of the SHP-2 tyrosine phosphatase by a novel cholesterol- and cell confluence-dependent mechanism.
abstract: Endothelial cells approaching confluence exhibit marked decreases in tyrosine phosphorylation of receptor tyrosine kinases and adherens junctions proteins, required for cell cycle arrest and adherens junctions stability. Recently, we demonstrated a close correlation in endothelial cells between membrane cholesterol and tyrosine phosphorylation of adherens junctions proteins. Here, we probe the mechanistic basis for this correlation. We find that as endothelial cells reach confluence, the tyrosine phosphatase SHP-2 is recruited to a low-density membrane fraction in a cholesterol-dependent manner. Binding of SHP-2 to this fraction was not abolished by phenyl phosphate, strongly suggesting that this binding was mediated by other regions of SHP-2 beside its SH2 domains. Annexin II, previously implicated in cholesterol trafficking, was associated in a complex with SHP-2, and both proteins localized to adhesion bands in confluent endothelial monolayers. These studies reveal a novel, cholesterol-dependent mechanism for the recruitment of signaling proteins to specific plasma membrane domains via their interactions with annexin II.
authors.affiliation: Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
authors.forename: Alison
authors.initials: A
authors.lastname: Burkart
authors.forename: Babak
authors.initials: B
authors.lastname: Samii
authors.forename: Silvia
authors.initials: S
authors.lastname: Corvera
authors.forename: Howard S
authors.initials: HS
authors.lastname: Shpetner
mesh_terms: D000818:Animals; D017306:Annexin A2 / Q000378:metabolism; D001011:Aorta / Q000166:cytology; D002417:Cattle; D002448:Cell Adhesion; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D003505:Cyclodextrins / Q000494:pharmacology; D004072:Digitonin / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology; D015971:Gene Expression Regulation, Enzymologic; D007202:Indicators and Reagents / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction; D013347:Subcellular Fractions; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D017306:Annexin A2; D003505:Cyclodextrins; D007202:Indicators and Reagents; D047908:Intracellular Signaling Peptides and Proteins; D014443:Tyrosine; D002784:Cholesterol; D011505:Protein-Tyrosine Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D004072:Digitonin