title: CAIR-1/BAG-3 modulates cell adhesion and migration by downregulating activity of focal adhesion proteins.
abstract: CAIR-1/BAG-3 is a stress and survival protein that has been shown to bind SH3 domain-containing proteins through its proline-rich (PXXP) domain. Because stress and survival pathways are active during invasion and metastasis, we hypothesized that CAIR-1 is a regulator of signaling pathways that modulate cell adhesion and migration. MDA-435 human breast carcinoma cells were stably transfected with full-length CAIR-1 (FL) or a proline-rich domain deleted mutant (dPXXP). FL cells migrated poorly through collagen IV-coated filters to serum (14% of control, p=0.0004), whereas migration of dPXXP cells was more robust (228%, p=0.00001). Adhesion to collagen IV-coated surfaces was reduced in FL cells and augmented in dPXXP cells (FL 64%, p=0.03; dPXXP 138%, p=0.01). Rhodamine-phalloidin staining highlighted more stress fibers and thicker filopodial protrusions in dPXXP cells. Fewer focal adhesions were also seen in FL cells. A reduction in tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin occurred in FL cells under these conditions. In contrast, increased FAK and paxillin phosphorylation was documented in dPXXP cells. Differential FAK phosphorylation occurred at the major autophosphorylation site Y(397) and Src phosphorylation site Y(861). Concordant with these findings, there was decreased interaction between FAK and its downstream partners p(130)Cas and Crk observed in FL cells but not in dPXXP cells. These results collectively indicate that CAIR-1 may negatively regulate adhesion, focal adhesion assembly, signaling, and migration via its PXXP domain.
authors.affiliation: Molecular Signaling Section, Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, 10 Center Drive, MSC 1500, Bethesda, MD 20892-1500, USA. kassisj@mail.nih.gov
authors.forename: Jareer N
authors.initials: JN
authors.lastname: Kassis
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Guancial
authors.forename: Howard
authors.initials: H
authors.lastname: Doong
authors.forename: Victoria
authors.initials: V
authors.lastname: Virador
authors.forename: Elise C
authors.initials: EC
authors.lastname: Kohn
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D051017:Apoptosis Regulatory Proteins; D001943:Breast Neoplasms / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D002465:Cell Movement / Q000235:genetics; D015536:Down-Regulation; D005260:Female; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism*; D022001:Focal Adhesions / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D051419:Paxillin / Q000235:genetics / Q000378:metabolism*; D011392:Proline / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C414431:BAG3 protein, human; C496061:PXN protein, human; D051419:Paxillin; D011392:Proline; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human