AF-6 Controls Integrin-mediated Cell Adhesion by Regulating Rap1 Activation through the Specific Recruitment of Rap1GTP and SPA-1

Su, Li; Hattori, Masao; Moriyama, Masaki; Murata, Norihito; Harazaki, Masashi; Kaibuchi, Kozo; Minato, Nagahiro

doi:10.1074/jbc.m211888200

Cited by 88 publications

(81 citation statements)

References 28 publications

(26 reference statements)

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“…This difference may be due to variations in the Afadin isoforms expressed, their ability to bind to actin, or the potential absence of an effect of Afadin on ␤1 integrin in MCF10A cells. Additionally, the PDZ binding motif of Afadin has been reported to bind to Rap1GAP, which inactivates Rap1 (Su et al, 2003). It is possible that JAM-A and Rap1GAP compete for binding of Afadin, because they interact with the same protein domain, and such competitive binding could produce cell-type-specific responses.…”

Section: Discussionmentioning

confidence: 99%

Junctional Adhesion Molecule A Interacts with Afadin and PDZ-GEF2 to Activate Rap1A, Regulate β1 Integrin Levels, and Enhance Cell Migration

Severson

Lee

Capaldo

et al. 2009

MBoC

159

166

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Junctional adhesion molecule-A (JAM-A) is a transmembrane tight junction protein that has been shown to regulate barrier function and cell migration through incompletely understood mechanisms. We have previously demonstrated that JAM-A regulates cell migration by dimerization of the membrane-distal immunoglobulin-like loop and a C-terminal postsynaptic density 95/disc-large/zona occludens (PDZ) binding motif. Disruption of dimerization resulted in decreased epithelial cell migration secondary to diminished levels of ␤1 integrin and active Rap1. Here, we report that JAM-A is physically and functionally associated with the PDZ domain-containing molecules Afadin and PDZ-guanine nucleotide exchange factor (GEF) 2, but not zonula occludens (ZO)-1, in epithelial cells, and these interactions mediate outside-in signaling events. Both Afadin and PDZ-GEF2 colocalized and coimmunoprecipitated with JAM-A. Furthermore, association of PDZ-GEF2 with Afadin was dependent on the expression of JAM-A. Loss of JAM-A, Afadin, or PDZ-GEF2, but not ZO-1 or PDZ-GEF1, similarly decreased cellular levels of activated Rap1, ␤1 integrin protein, and epithelial cell migration. The functional effects observed were secondary to decreased levels of Rap1A because knockdown of Rap1A, but not Rap1B, resulted in decreased ␤1 integrin levels and reduced cell migration. These findings suggest that JAM-A dimerization facilitates formation of a complex with Afadin and PDZ-GEF2 that activates Rap1A, which regulates ␤1 integrin levels and cell migration.

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Section: Discussionmentioning

confidence: 99%

Junctional Adhesion Molecule A Interacts with Afadin and PDZ-GEF2 to Activate Rap1A, Regulate β1 Integrin Levels, and Enhance Cell Migration

Severson

Lee

Capaldo

et al. 2009

MBoC

159

166

View full text Add to dashboard Cite

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“…However, the underlying mechanism is unclear. It is conceivable that RapGAPs such as Rap1GAP and SPA-1, which were previously reported to interact with afadin, 37 could be involved. Indeed, we recently reported that the interaction of Rap1 with afadin increases the activity of Rap1 in NIH3T3 cells and that this interaction prevents the SPA-1-induced inactivation of Rap1.…”

Section: Discussionmentioning

confidence: 99%

Role of Afadin in Vascular Endothelial Growth Factor– and Sphingosine 1-Phosphate–Induced Angiogenesis

Tawa

Rikitake

Takahashi

et al. 2010

Circulation Research

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“…The similar effects of Rap1GAP overexpression and downregulation may indicate that Rap1GAP functions as part of a macromolecular complex, where alterations in Rap1GAP expression impact stoichiometry. Besides interacting with Rap, Rap1GAP binds to heterotrimeric G protein ␣ subunits (27,33,35) and AF6 (43,55), a protein that associates with activated Rap and localizes to cell/cell junctions (7).…”

Section: Discussionmentioning

confidence: 99%

Downregulation of Rap1GAP in Human Tumor Cells Alters Cell/Matrix and Cell/Cell Adhesion

Tsygankova

Tang

et al. 2010

Molecular and Cellular Biology

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Rap1GAP expression is decreased in human tumors. The significance of its downregulation is unknown. We show that Rap1GAP expression is decreased in primary colorectal carcinomas. To elucidate the advantages conferred on tumor cells by loss of Rap1GAP, Rap1GAP expression was silenced in human colon carcinoma cells. Suppressing Rap1GAP induced profound alterations in cell adhesion. Rap1GAP-depleted cells exhibited defects in cell/cell adhesion that included an aberrant distribution of adherens junction proteins. Depletion of Rap1GAP enhanced adhesion and spreading on collagen. Silencing of Rap expression normalized spreading and restored E-cadherin, ␤-catenin, and p120-catenin to cell/cell contacts, indicating that unrestrained Rap activity underlies the alterations in cell adhesion. The defects in adherens junction protein distribution required integrin signaling as E-cadherin and p120-catenin were restored at cell/cell contacts when cells were plated on poly-L-lysine. Unexpectedly, Src activity was increased in Rap1GAP-depleted cells. Inhibition of Src impaired spreading and restored E-cadherin at cell/cell contacts. These findings provide the first evidence that Rap1GAP contributes to cell/cell adhesion and highlight a role for Rap1GAP in regulating cell/matrix and cell/cell adhesion. The frequent downregulation of Rap1GAP in epithelial tumors where alterations in cell/cell and cell/matrix adhesion are early steps in tumor dissemination supports a role for Rap1GAP depletion in tumor progression.Mammalian Rap proteins Rap1a/b and Rap2a/b/c are members of the Ras superfamily of small GTPases. Rap proteins are active when bound to GTP and inactive when bound to GDP. Cellular Rap activity is regulated by the concerted action of guanine nucleotide exchange factors that activate Rap (RapGEFs) and Rap-specific GTPaseactivating proteins (RapGAPs) that inactivate Rap (reviewed in reference 10). The Rap1GAP family is composed of several members, including Rap1GAP, Rap1GAPII, Spa-1/SIPA1, and E6TP1/SIPA1L1. Several lines of evidence suggest that RapGAPs function as tumor and/or invasion suppressors. Downregulation of E6TP1 by human papillomavirus protein E6 contributes to cervical cancer (20, 21), and Spa-1 deficiency in mice induces a spectrum of myelodysplastic disorders similar to chronic myelogenous leukemia (26). The SPA1 gene was identified as a candidate for the metastasis efficiency modifier locus in mice (38). Although the relevance of this observation to humans is not yet clear, single-nucleotide polymorphisms in the SPA1 gene in human breast tumors have been associated with lymph node involvement and poor survival (15). Intriguingly, Spa-1 interacts with Brd4 (18) and Rrp-1b (13), the protein products of genes associated with patterns of extracellular matrix protein gene expression characteristic of metastatic tumors (14).The RAP1GAP gene maps to 1p35-36, a chromosomal region subject to copy number alterations in human tumors (36, 49). Rap1GAP protein levels are decreased in pancreatic adenocarcinomas (53), pap...

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AF-6 Controls Integrin-mediated Cell Adhesion by Regulating Rap1 Activation through the Specific Recruitment of Rap1GTP and SPA-1

Cited by 88 publications

References 28 publications

Junctional Adhesion Molecule A Interacts with Afadin and PDZ-GEF2 to Activate Rap1A, Regulate β1 Integrin Levels, and Enhance Cell Migration

Junctional Adhesion Molecule A Interacts with Afadin and PDZ-GEF2 to Activate Rap1A, Regulate β1 Integrin Levels, and Enhance Cell Migration

Role of Afadin in Vascular Endothelial Growth Factor– and Sphingosine 1-Phosphate–Induced Angiogenesis

Downregulation of Rap1GAP in Human Tumor Cells Alters Cell/Matrix and Cell/Cell Adhesion

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