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Proteolysis-induced N-terminal ectodomain shedding of the integral membrane glycoprotein CUB domain-containing protein 1 (CDCP1) is accompanied by tyrosine phosphorylation of its C-terminal domain and recruitment of Src and PKCdelta.

ABSTRACT: CUB-domain-containing protein 1 (CDCP1) is an integral membrane glycoprotein with potential as a marker and therapeutic target for a number of cancers. Here we examine mechanisms regulating cellular processing of CDCP1. By analyzing cell lines exclusively passaged non-enzymatically and through use of a panel of protease inhibitors, we demonstrate that full-length 135 kDa CDCP1 is post-translationally processed in a range of cell lines by a mechanism involving serine protease activity, generating a C-terminal 70-kDa fragment. Immunopurification and N-terminal sequencing of this cell-retained fragment and detailed mutagenesis, show that proteolytic processing of CDCP1 occurs at two sites, Arg-368 and Lys-369. We show that the serine protease matriptase is an efficient, but not essential, cellular processor of CDCP1 at Arg-368. Importantly, we also demonstrate that proteolysis induces tyrosine phosphorylation of 70-kDa CDCP1 and recruitment of Src and PKCdelta to this fragment. In addition, Western blot and mass spectroscopy analyses show that an N-terminal 65-kDa CDCP1 ectodomain is shed intact from the cell surface. These data provide new insights into mechanisms regulating CDCP1 and suggest that the biological role of this protein and, potentially, its function in cancer, may be mediated by both 70-kDa cell retained and 65-kDa shed fragments, as well as the full-length 135-kDa protein.

SUBMITTER: He Y

PROVIDER: S-EPMC2924022 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Proteolysis-induced N-terminal ectodomain shedding of the integral membrane glycoprotein CUB domain-containing protein 1 (CDCP1) is accompanied by tyrosine phosphorylation of its C-terminal domain and recruitment of Src and PKCdelta.

He Yaowu Y Wortmann Andreas A Burke Les J LJ Reid Janet C JC Adams Mark N MN Abdul-Jabbar Ibtissam I Quigley James P JP Leduc Richard R Kirchhofer Daniel D Hooper John D JD

The Journal of biological chemistry 20100615 34

CUB-domain-containing protein 1 (CDCP1) is an integral membrane glycoprotein with potential as a marker and therapeutic target for a number of cancers. Here we examine mechanisms regulating cellular processing of CDCP1. By analyzing cell lines exclusively passaged non-enzymatically and through use of a panel of protease inhibitors, we demonstrate that full-length 135 kDa CDCP1 is post-translationally processed in a range of cell lines by a mechanism involving serine protease activity, generating ...[more]

PMID: 20551327

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Project description:BackgroundDeregulated expression of the transmembrane glycoprotein CDCP1 (CUB domain-containing protein-1) has been detected in several cancers including colon, lung, gastric, breast, and pancreatic carcinomas. CDCP1 has been proposed to either positively or negatively regulate tumour metastasis. In this study we assessed the role of CDCP1 in properties of cells that are directly relevant to metastasis, namely adhesion and motility. In addition, association between CDCP1 and the tetraspanin protein CD9 was investigated.MethodsCDCP1 and CD9 protein expression was measured in a series of colon cancer cell lines by flow cytometry and Western blotting. Adhesion of Colo320 and SW480 cells was determined using a Matrigel adhesion assay. The chemotactic motility of SW480 cells in which CDCP1 expression had been reduced by RNA interference was analysed using the xCELLigence system Real-Time Cell Analyzer Dual Plates combined with 8 μm pore filters. Detergent-resistant membrane fractions were generated following density gradient centrifugation and the CDCP1 and CD9 protein composition of these fractions was determined by Western blotting. The potential association of the CDCP1 and CD9 proteins was assessed by co-immunoprecipitation.ResultsEngineered CDCP1 expression in Colo320 cells resulted in a reduction in cell adhesion to Matrigel. Treatment of SW480 cells with CDCP1 siRNA reduced serum-induced chemotaxis. CDCP1 and CD9 cell-surface protein and mRNA levels showed a positive correlation in colon cancer cell lines and the proteins formed a low-level, but detectable complex as judged by co-sedimentation of detergent lysates of HT-29 cells in sucrose gradients as well as by co-immunoprecipitation in SW480 cell lysates.ConclusionsA number of recent studies have assigned a potentially important role for the cell-surface protein CDCP1 in invasion and metastasis of a several types of human cancer cells. In this study, CDCP1 was shown to modulate cell-substratum adhesion and motility in colon cancer cell lines, with some variation depending on the colon cancer cell type. CDCP1 and CD9 were co-expressed at the mRNA and protein level and we obtained evidence for the presence of a molecular complex of these proteins in SW480 colon cancer cells.

Dataset Information

Proteolysis-induced N-terminal ectodomain shedding of the integral membrane glycoprotein CUB domain-containing protein 1 (CDCP1) is accompanied by tyrosine phosphorylation of its C-terminal domain and recruitment of Src and PKCdelta.

Publications

Proteolysis-induced N-terminal ectodomain shedding of the integral membrane glycoprotein CUB domain-containing protein 1 (CDCP1) is accompanied by tyrosine phosphorylation of its C-terminal domain and recruitment of Src and PKCdelta.

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