p130Cas regulates the activity of AND-34, a novel Ral, Rap1, and R-Ras guanine nucleotide exchange factor.
We previously identified a novel murine protein, AND-34, with a carboxyl-terminal domain homologous to Ras family guanine nucleotide exchange factors (GEFs), which bound to the focal adhesion docking protein p130(Cas). Work by others has implicated both the human homologue of AND-34, BCAR3, and human p130(Cas), BCAR1, in the resistance of breast cancer cells to the anti-estrogen tamoxifen. Here we report that AND-34 displays GEF activity on RalA, Rap1A, and R-Ras but not Ha-Ras GTPases in cells. In contrast to several other Ral-GEFs, the Ral GEF activity of AND-34 is not augmented by constitutively active Ha-Ras(Val-12), consistent with the absence of a detectable Ras-binding domain. Efficient binding to AND-34 required both the Src-binding domain and a flanking carboxyl-terminal region of p130(Cas). The p130(Cas)-binding site mapped to a carboxyl-terminal sequence within the AND-34 GEF domain. Overexpression of p130(Cas), but not an AND-34-binding mutant of p130(Cas), inhibited the Ral GEF activity of co-transfected AND-34. This work identifies a new potential function for p130(Cas) and a new regulatory pathway involved in the control of Ral, Rap, and R-Ras GTPases that may participate in the progression of breast cancer cells to tamoxifen resistance.
Gotoh
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Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Cai
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Tian
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Feig
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Lerner
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D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites; D001943:Breast Neoplasms / Q000188:drug therapy; D050719:Crk-Associated Substrate Protein; D004351:Drug Resistance; D005260:Female; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006801:Humans; D051379:Mice; D009154:Mutation; D010446:Peptide Fragments; D010750:Phosphoproteins / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D050717:Retinoblastoma-Like Protein p130; D017384:Sequence Deletion; D013629:Tamoxifen / Q000494:pharmacology; D020725:ral GTP-Binding Proteins; D018631:ras Proteins / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; C493841:BCAR1 protein, human; C493842:Bcar1 protein, mouse; C120867:Bcar3 protein, mouse; D050719:Crk-Associated Substrate Protein; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D010446:Peptide Fragments; D010750:Phosphoproteins; D011506:Proteins; D050717:Retinoblastoma-Like Protein p130; C116071:rap1a-GTPase activating proteins, human; C485482:smg p21 GAP1 protein, human; C485483:smg p21 GAP2 protein, human; D013629:Tamoxifen; D006153:Guanosine Diphosphate; D016392:Proto-Oncogene Proteins pp60(c-src); D020558:GTP Phosphohydrolases; C492198:RALA protein, human; C118120:Rala protein, mouse; D020725:ral GTP-Binding Proteins; D018631:ras Proteins