RESUMO
This study investigated the regulation of 14-3-3ß binding to PTPIP51 by the tyrosine phosphorylation status of PTPIP51. The tyrosine 176 residue is phosphorylated by c-Src. Up to now, nothing is known about the impact of such well-established phosphorylation events on the interaction profile of PTPIP51 with its partners of the mitogen-activated protein kinase (MAPK) pathway. In human keratinocytes the PTPIP51 phosphorylation was varied by inhibiting the phosphatase activity, thus enhancing the phosphorylation of PTPIP51. Differential blocking of Src kinase family members (despite c-Src) by PP2 increased the activity of c-Src and the tyrosine phosphorylation of PTPIP51 at position 176, which is the substrate of c-Src kinase. The amount of PTPIP51 interactions with 14-3-3ß, Raf-1, PTP1B and c-Src was evaluated and the resulting data were compared to an untreated control group. The increased phosphorylation level resulted in a sharp drop of the 14-3-3ß/PTPIP51 and 14-3-3ß/Raf-1 interaction. Besides the 14-3-3 interaction of PTPIP51, the interaction with the two MAPK modulators, protein kinase A (PKA) and diacylglycerol kinase alpha (DAGKα), are also regulated by the tyrosine phosphorylation status of PTPIP51. Additional immunostaining experiments were done investigating the functional implication on these interactions of the phosphorylation in apoptotic processes. In the pervanadate- and PP2-treated HaCaT cells, higher amounts of apoptotic cells were not detected as compared to the control group. The presented data confirms a tyrosine phosphorylation-dependent interaction of PTPIP51 with 14-3-3ß and Raf-1 in vivo and a tyrosine-dependent interaction profile with DAGKα and PKA. The non-interaction of PTPIP51 with 14-3-3 is not sufficient for triggering apoptosis.
Assuntos
Proteínas 14-3-3/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Apoptose/efeitos dos fármacos , Linhagem Celular , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Diacilglicerol Quinase/metabolismo , Humanos , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Fosforilação , Ligação Proteica , Mapeamento de Interação de Proteínas , Proteínas Proto-Oncogênicas c-raf/metabolismo , Pirimidinas/farmacologia , Vanadatos/farmacologia , Quinases da Família src/antagonistas & inibidores , Quinases da Família src/metabolismoRESUMO
Protein tyrosine phosphatase interacting protein 51 (PTPIP51) is known to be expressed in blood cells with restriction to the myeloid lineage. All myeloid progenitor cells are PTPIP51 positive except for the myeloblasts. To define the expression of PTPIP51 in acute myeloid leukemia (AML), we performed immunohistochemical experiments with peptide specific antibodies (C-terminus, N-terminus and aas 114-129) to PTPIP51 with samples of AML bone marrow trephine biopsy specimens. AML blasts reacted positive for PTPIP51 protein encompassing the C-terminal sequence. Healthy bone marrow displayed an exclusive staining for the N-terminal containing form of PTPIP51. Moreover, PTPIP51 protein was highly phosphorylated at its tyrosine 176 residue. Acquired confocal images of AML cells displayed an absence of PTP1B and revealed a co-localization of PTPIP51 and Lyn. Duolink proximity ligation assays (DPLA) corroborated an interaction for PTPIP51 with Lyn and c-Src. In AML blasts rarely an interaction of PTPIP51 with PTP1B and Raf-1 was seen. Furthermore, DPLA signals were also obtained for PTPIP51 and c-Kit in AML cells. Therefore, PTPIP51 was identified as a new signal molecule of the c-Kit signaling pathway. By the phosphorylation done by Lyn, c-Src and c-Kit, PTPIP51 is prevented to influence mitogen activated protein kinase pathway on Raf-1 level contributing to increased proliferation of AML cells.
Assuntos
Medula Óssea/metabolismo , Expressão Gênica , Leucemia Mieloide Aguda/metabolismo , Células Progenitoras Mieloides/metabolismo , Transdução de Sinais , Adulto , Anticorpos/análise , Medula Óssea/patologia , Proteína Tirosina Quinase CSK , Sondas de DNA , Feminino , Humanos , Imuno-Histoquímica , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Microscopia de Fluorescência , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Células Progenitoras Mieloides/patologia , Fosforilação , Processamento de Proteína Pós-Traducional , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Proteínas Tirosina Fosfatases/genética , Proteínas Tirosina Fosfatases/metabolismo , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-kit/genética , Proteínas Proto-Oncogênicas c-kit/metabolismo , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/genética , Tirosina/metabolismo , Quinases da Família src/genética , Quinases da Família src/metabolismoRESUMO
Protein tyrosine phosphatase interacting protein 51 (PTPIP51) interacts both in vitro and in vivo with PTP1B, a protein tyrosine phosphatase involved in cellular regulation. PTPIP51 is known to be expressed in many different types of tissues. It is involved in cellular processes such as proliferation, differentiation and apoptosis. Nevertheless, the exact cellular function of PTPIP51 is still unknown. The present review summarizes our current knowledge of the PTPIP51 gene and its mRNA and protein structure.
