title: PTPN4 negatively regulates CrkI in human cell lines.
abstract: PTPN4 is a widely expressed non-receptor protein tyrosine phosphatase. Although its overexpression inhibits cell growth, the proteins with which it interacts to regulate cell growth are unknown. In this study, we identified CrkI as a PTPN4-interacting protein using a yeast two-hybrid, and confirmed this interaction using in vitro GST pull-down and co-immunoprecipitation and co-localization assays. We further determined the interactional regions as the SH3 domain of CrkI and the proline-rich region between amino acids 462 and 468 of PTPN4. Notably, overexpression of PTPN4 inhibits CrkI-mediated proliferation and wound healing of HEK293T cells, while knockdown of PTPN4 by siRNA in Hep3B cells enhances CrkI-mediated cell growth and motility. Moreover, our data show that ectopic expression of PTPN4 reduces the phosphorylation level of CrkI in HEK293T cells. These findings suggest that PTPN4 negatively regulates cell proliferation and motility through dephosphorylation of CrkI.
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhou
authors.forename: Bingbing
authors.initials: B
authors.lastname: Wan
authors.forename: Jingxuan
authors.initials: J
authors.lastname: Shan
authors.forename: Huili
authors.initials: H
authors.lastname: Shi
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Li
authors.forename: Keke
authors.initials: K
authors.lastname: Huo
mesh_terms: D000595:Amino Acid Sequence; D002465:Cell Movement; D049109:Cell Proliferation; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D054590:Protein Tyrosine Phosphatase, Non-Receptor Type 4 / Q000737:chemistry / Q000378:metabolism*; D050737:Proto-Oncogene Proteins c-crk / Q000378:metabolism*; D034622:RNA Interference; D015203:Reproducibility of Results
chemical_list: D050737:Proto-Oncogene Proteins c-crk; C516658:PTPN4 protein, human; D054590:Protein Tyrosine Phosphatase, Non-Receptor Type 4