title: Prolactin induces SHP-2 association with Stat5, nuclear translocation, and binding to the beta-casein gene promoter in mammary cells.
abstract: The Src homology 2 (SH2) domain containing protein-tyrosine phosphatase SHP-2 contributes to prolactin receptor (PRLR) signal transduction to beta-casein gene promoter activation. We report for the first time that SHP-2 physically associates with the signal transducer and activator of transcription-5a (Stat5a), an important mediator of PRLR signaling to milk protein gene activation, in the mouse mammary HC11 and the human breast cancer T47D cells when stimulated with prolactin (PRL) and human growth hormone, respectively. In addition, overexpression studies indicate that the carboxyl-terminal SH2 domain of SHP-2 is required to maintain tyrosine phosphorylation of Stat5 and its interaction with SHP-2. Furthermore, we demonstrate by nuclear co-immunoprecipitation and indirect immunofluorescence studies that PRL stimulation of mammary cells leads to the nuclear translocation of SHP-2 as a complex with Stat5a. This process was found to involve the catalytic activity of the phosphatase. Finally, using the Stat5 GAS (gamma-activated sequence) element of the beta-casein gene promoter in electrophoretic mobility shift assays, we demonstrate that PRL induces the SHP-2-Stat5a complex to bind to DNA. The presence of the phosphatase in the protein-bound DNA complex was verified by using polyclonal antisera to SHP-2. Our studies indicate a tight physical and functional interaction between SHP2 and Stat5 required for regulation and perpetuation of PRL-mediated signaling in mammary cells and suggest a potential role for SHP-2 in the nucleus.
authors.affiliation: Department of Medicine, Division of Hematology, Molecular Oncology Group, Royal Victoria Hospital, McGill University Health Centre, 687 Pine Avenue, Montreal, Quebec H3A 1A1, Canada.
authors.forename: Naila
authors.initials: N
authors.lastname: Chughtai
authors.forename: Sarah
authors.initials: S
authors.lastname: Schimchowitsch
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Lebrun
authors.forename: Suhad
authors.initials: S
authors.lastname: Ali
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D001940:Breast / Q000187:drug effects* / Q000378:metabolism; D002364:Caseins / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008894:Milk Proteins; D010766:Phosphorylation; D011388:Prolactin / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D002364:Caseins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008894:Milk Proteins; D050799:STAT5 Transcription Factor; C494092:STAT5A protein, human; C494093:Stat5a protein, mouse; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D014443:Tyrosine; D011388:Prolactin; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases