RESUMO
Genome-wide association studies revealed that loss-of-function mutations in protein tyrosine phosphatase non-receptor type 2 (PTPN2) increase the risk of developing chronic immune diseases, such as inflammatory bowel disease (IBD) and celiac disease. These conditions are associated with increased intestinal permeability as an early etiological event. The aim of this study was to examine the consequences of deficient activity of the PTPN2 gene product, T cell protein tyrosine phosphatase (TCPTP), on intestinal barrier function and tight junction organization in vivo and in vitro. Here, we demonstrate that TCPTP protected against intestinal barrier dysfunction induced by the inflammatory cytokine IFN-γ by 2 mechanisms: it maintained localization of zonula occludens 1 and occludin at apical tight junctions and restricted both expression and insertion of the cation pore-forming transmembrane protein, claudin-2, at tight junctions through upregulation of the inhibitory cysteine protease, matriptase. We also confirmed that the loss-of-function PTPN2 rs1893217 SNP was associated with increased intestinal claudin-2 expression in patients with IBD. Moreover, elevated claudin-2 levels and paracellular electrolyte flux in TCPTP-deficient intestinal epithelial cells were normalized by recombinant matriptase. Our findings uncover distinct and critical roles for epithelial TCPTP in preserving intestinal barrier integrity, thereby proposing a mechanism by which PTPN2 mutations contribute to IBD.
Assuntos
Mucosa Intestinal/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Junções Íntimas/metabolismo , Adolescente , Adulto , Idoso , Animais , Claudinas/metabolismo , Modelos Animais de Doenças , Feminino , Estudo de Associação Genômica Ampla , Humanos , Técnicas In Vitro , Doenças Inflamatórias Intestinais/etiologia , Doenças Inflamatórias Intestinais/genética , Doenças Inflamatórias Intestinais/metabolismo , Mucosa Intestinal/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Permeabilidade , Polimorfismo de Nucleotídeo Único , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Junções Íntimas/patologia , Adulto JovemRESUMO
Protein tyrosine phosphatase nonreceptor type 2 (PTPN2) plays a critical role in the pathogenesis of inflammatory bowel diseases (IBD). Mice lacking PTPN2 in dendritic cells (DCs) develop skin and liver inflammation by the age of 22 weeks due to a generalized loss of tolerance leading to uncontrolled immune responses. The effect of DC-specific PTPN2 loss on intestinal health, however, is unknown. The aim of this study was to investigate the DC-specific role of PTPN2 in the intestine during colitis development. PTPN2fl/flxCD11cCre mice were subjected to acute and chronic DSS colitis as well as T cell transfer colitis. Lamina propria immune cell populations were analyzed using flow cytometry. DC-specific PTPN2 deletion promoted infiltration of B and T lymphocytes, macrophages, and DCs into the lamina propria of unchallenged mice and elevated Th1 abundance during acute DSS colitis, suggesting an important role for PTPN2 in DCs in maintaining intestinal immune cell homeostasis. Surprisingly, those immune cell alterations did not translate into increased colitis susceptibility in acute and chronic DSS-induced colitis or T cell transfer colitis models. However, macrophage depletion by clodronate caused enhanced colitis severity in mice with a DC-specific loss of PTPN2. Loss of PTPN2 in DCs affects the composition of lamina propria lymphocytes, resulting in increased infiltration of innate and adaptive immune cells. However, this did not result in an elevated colitis phenotype, likely because increased infiltration of macrophages in the intestine upon loss of PTPN2 loss in DCs can compensate for the inflammatory effect of PTPN2-deficient DCs.
Assuntos
Colite/etiologia , Colite/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Animais , Colite/patologia , Sulfato de Dextrana/efeitos adversos , Modelos Animais de Doenças , Suscetibilidade a Doenças , Mucosa Intestinal/imunologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Camundongos , Camundongos Transgênicos , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Fator de Transcrição STAT1/metabolismo , Índice de Gravidade de Doença , Transdução de Sinais , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Subpopulações de Linfócitos T/patologiaRESUMO
Protein tyrosine phosphatase nonreceptor type 2 (PTPN2) is a phosphatase known to be a tumor suppressor gene in T-cell acute lymphoblastic leukemia (T-ALL). Because the full clinicobiologic characteristics of PTPN2 loss remain poorly reported, we aimed to provide a comprehensive analysis of PTPN2 deletions within a cohort of 430 patients, including 216 adults and 214 children treated according to the GRAALL03/05 (#NCT00222027 and #NCT00327678) and the FRALLE2000 protocols, respectively. We used multiplex ligation-dependent probe amplification to identify an 8% incidence of PTPN2 deletion, which was comparable in adult (9%) and pediatric (6%) populations. PTPN2 deletions were significantly associated with an αß lineage and TLX1 deregulation. Analysis of the mutational genotype of adult T-ALL revealed a positive correlation between PTPN2 deletions and gain-of-function alterations in the IL7R/JAK-STAT signaling pathway as well as PHF6 and WT1 mutations. Of note, PTPN2 and PTEN (phosphatase and tensin homolog) deletions were mutually exclusive. Regarding treatment response, PTPN2-deleted T-ALLs were associated with a higher glucocorticoid response and a trend for improved survival in children, but not in adults, with a 5-year cumulative incidence of relapse of 8% for PTPN2-deleted pediatric cases vs 26% (P = .177).
Assuntos
Leucemia-Linfoma Linfoblástico de Células T Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Adolescente , Adulto , Alelos , Biomarcadores Tumorais , Feminino , Frequência do Gene , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Imunofenotipagem , Subunidade alfa de Receptor de Interleucina-7/genética , Subunidade alfa de Receptor de Interleucina-7/metabolismo , Janus Quinases/metabolismo , Masculino , Pessoa de Meia-Idade , Leucemia-Linfoma Linfoblástico de Células T Precursoras/mortalidade , Leucemia-Linfoma Linfoblástico de Células T Precursoras/terapia , Prognóstico , Fatores de Transcrição STAT/metabolismo , Deleção de Sequência , Adulto JovemRESUMO
PURPOSE: The protein tyrosine phosphatase PTPN2 dephosphorylates several tyrosine kinases in cancer-related signalling pathways and is thought to be a tumour suppressor. As PTPN2 is not frequently studied in breast cancer, we aimed to explore the role of PTPN2 and the effects of its loss in breast cancer. METHODS: Protein expression and gene copy number of PTPN2 were analysed in a cohort of pre-menopausal breast cancer patients with immunohistochemistry and droplet digital PCR, respectively. PTPN2 was knocked down in three cell lines, representing different breast cancer subtypes, with siRNA transfection. Several proteins related to PTPN2 were analysed with Western blot. RESULTS: Low PTPN2 protein expression was found in 50.2% of the tumours (110/219), gene copy loss in 15.4% (33/214). Low protein expression was associated with a higher relapse rate in patients with Luminal A and HER2-positive tumours, but not triple-negative tumours. In vitro studies further suggested a subtype-specific role of PTPN2. Knockdown of PTPN2 had no effect on the triple-negative cell line, whilst knockdown in MCF7 inhibited phosphorylation of Met and promoted that of Akt. Knockdown in SKBR3 led to increased Met phosphorylation and decreased Erk phosphorylation as well as EGF-mediated STAT3 activation. CONCLUSION: We confirm previous studies showing that the PTPN2 protein is lost in half of the breast cancer cases and gene deletion occurs in 15-18% of the cases. Furthermore, the results suggest that the role of PTPN2 is subtype-related and should be further investigated to assess how this could affect breast cancer prognosis and treatment response.
Assuntos
Neoplasias da Mama/classificação , Neoplasias da Mama/enzimologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Comunicação Celular , Linhagem Celular Tumoral , Intervalo Livre de Doença , Feminino , Dosagem de Genes , Técnicas de Silenciamento de Genes , Humanos , Imuno-Histoquímica , Células MCF-7 , Prognóstico , Proteína Tirosina Fosfatase não Receptora Tipo 2/biossíntese , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Receptor ErbB-2/biossíntese , Neoplasias de Mama Triplo Negativas/classificação , Neoplasias de Mama Triplo Negativas/enzimologia , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
PURPOSE: The protein tyrosine phosphatase, non-receptor type 2 (PTNP2) regulates receptor tyrosine kinase signalling, preventing downstream activation of intracellular pathways like the PI3K/Akt pathway. The gene encoding the protein is located on chromosome 18p11; the 18p region is commonly deleted in breast cancer. In this study, we aimed to evaluate PTPN2 protein expression in a large breast cancer cohort, its possible associations to PTPN2 gene copy loss, Akt activation, and the potential use as a clinical marker in breast cancer. METHODS: PTPN2 protein expression was analysed by immunohistochemistry in 664 node-negative breast tumours from patients enrolled in a randomised tamoxifen trial. DNA was available for 146 patients, PTPN2 gene copy number was determined by real-time PCR. RESULTS: PTPN2 gene loss was detected in 17.8% of the tumours. Low PTPN2 protein expression was associated with higher levels of nuclear-activated Akt (pAkt-n). Low PTPN2 as well as the combination variable low PTPN2/high pAkt-n could be used as predictive markers of poor tamoxifen response. CONCLUSION: PTPN2 negatively regulates Akt signalling and loss of PTPN2 protein along with increased pAkt-n is a new potential clinical marker of endocrine treatment efficacy, which may allow for further tailored patient therapies.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteínas Proto-Oncogênicas c-akt/metabolismo , Antineoplásicos Hormonais/uso terapêutico , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Feminino , Dosagem de Genes , Humanos , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Retrospectivos , Tamoxifeno/uso terapêuticoRESUMO
Obesity is a major driver of cancer, especially hepatocellular carcinoma (HCC). The prevailing view is that non-alcoholic steatohepatitis (NASH) and fibrosis or cirrhosis are required for HCC in obesity. Here, we report that NASH and fibrosis and HCC in obesity can be dissociated. We show that the oxidative hepatic environment in obesity inactivates the STAT-1 and STAT-3 phosphatase T cell protein tyrosine phosphatase (TCPTP) and increases STAT-1 and STAT-3 signaling. TCPTP deletion in hepatocytes promoted T cell recruitment and ensuing NASH and fibrosis as well as HCC in obese C57BL/6 mice that normally do not develop NASH and fibrosis or HCC. Attenuating the enhanced STAT-1 signaling prevented T cell recruitment and NASH and fibrosis but did not prevent HCC. By contrast, correcting STAT-3 signaling prevented HCC without affecting NASH and fibrosis. TCPTP-deletion in hepatocytes also markedly accelerated HCC in mice treated with a chemical carcinogen that promotes HCC without NASH and fibrosis. Our studies reveal how obesity-associated hepatic oxidative stress can independently contribute to the pathogenesis of NASH, fibrosis, and HCC.
Assuntos
Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , Obesidade/patologia , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/metabolismo , Animais , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Carcinoma Hepatocelular/metabolismo , Dieta Hiperlipídica , Modelos Animais de Doenças , Hepatócitos/metabolismo , Humanos , Fígado/metabolismo , Fígado/patologia , Cirrose Hepática/metabolismo , Cirrose Hepática/patologia , Neoplasias Hepáticas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/metabolismo , Obesidade/metabolismo , Estresse Oxidativo , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Transdução de SinaisRESUMO
Immunotherapy with PD-1 checkpoint blockade is effective in only a minority of patients with cancer, suggesting that additional treatment strategies are needed. Here we use a pooled in vivo genetic screening approach using CRISPR-Cas9 genome editing in transplantable tumours in mice treated with immunotherapy to discover previously undescribed immunotherapy targets. We tested 2,368 genes expressed by melanoma cells to identify those that synergize with or cause resistance to checkpoint blockade. We recovered the known immune evasion molecules PD-L1 and CD47, and confirmed that defects in interferon-γ signalling caused resistance to immunotherapy. Tumours were sensitized to immunotherapy by deletion of genes involved in several diverse pathways, including NF-κB signalling, antigen presentation and the unfolded protein response. In addition, deletion of the protein tyrosine phosphatase PTPN2 in tumour cells increased the efficacy of immunotherapy by enhancing interferon-γ-mediated effects on antigen presentation and growth suppression. In vivo genetic screens in tumour models can identify new immunotherapy targets in unanticipated pathways.
Assuntos
Sistemas CRISPR-Cas/genética , Edição de Genes , Imunoterapia/métodos , Melanoma Experimental/imunologia , Melanoma Experimental/terapia , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Evasão Tumoral/efeitos dos fármacos , Evasão Tumoral/imunologia , Animais , Apresentação de Antígeno/genética , Apresentação de Antígeno/imunologia , Genômica , Humanos , Interferons/imunologia , Mutação com Perda de Função , Melanoma Experimental/genética , Melanoma Experimental/patologia , Camundongos , NF-kappa B/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Evasão Tumoral/genética , Resposta a Proteínas não Dobradas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Non-coding single nucleotide polymorphisms that repress PTPN2 expression have been linked with the development of type 1 diabetes, rheumatoid arthritis and Crohn's disease. PTPN2 attenuates CD8+ T cell responses to self and prevents overt autoreactivity in the context of T cell homeostasis and antigen cross-presentation. The role of PTPN2 in other immune subsets in the development of autoimmunity remains unclear. Here we show that the inducible deletion of PTPN2 in hematopoietic compartment of adult non-autoimmune prone mice results in systemic inflammation and autoimmunity. PTPN2-deficient mice had increased inflammatory monocytes, B cells and effector T cells in lymphoid and non-lymphoid tissues and exhibited symptoms of dermatitis, glomerulonephritis, pancreatitis and overt liver disease. Autoimmunity was characterised by the formation of germinal centers in the spleen and associated with markedly increased germinal center B cells and T follicular helper (Tfh) cells and circulating anti-nuclear antibodies, inflammatory cytokines and immunoglobulins. CD8+ T cell proliferative responses were enhanced, and interleukin-21-induced STAT-3 signalling in Tfh cells and B cells was increased and accompanied by enhanced B cell proliferation ex vivo. These results indicate that deficiencies in PTPN2 across multiple immune lineages, including naive T cells, Tfh cells and B cells, contribute to the development of autoimmunity.
Assuntos
Autoimunidade/genética , Linfócitos B/imunologia , Linfócitos B/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Auxiliares-Indutores/metabolismo , Animais , Formação de Anticorpos/genética , Formação de Anticorpos/imunologia , Feminino , Deleção de Genes , Centro Germinativo/imunologia , Centro Germinativo/metabolismo , Hematopoese/genética , Hematopoese/imunologia , Inflamação/imunologia , Inflamação/metabolismo , Interleucinas/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Fator de Transcrição STAT3/metabolismo , Transdução de SinaisRESUMO
T cell protein tyrosine phosphatase N2 (PTPN2) is a phosphotyrosine-specific nonreceptor phosphatase and is ubiquitously expressed in tissues. Although PTPN2 functions as an important regulator in different signaling pathways, it is still unclear what is specific target protein of PTPN2 and how is regulated in lipopolysaccharide (LPS)-induced inflammatory signaling pathway. Here, we found that PTPN2 deficiency downregulated the expression of LPS-mediated pro-inflammtory cytokine genes. Conversely, overexpression of PTPN2 in Raw264.7 cells enhanced the expression and secretion of those cytokines. The activation of MAPK and NF-κB signaling pathways by LPS was reduced in PTPN2-knockdowned cells and ectopic expression of PTPN2 reversed these effects. Furthermore, we found that PTNP2 directly interacted with Src and removed the inhibitory Tyr527 phosphorylation of Src to enhance the activatory phosphorylation of Tyr416 residue. These results suggested that PTPN2 is a positive regulator of LPS-induced inflammatory response by enhancing the activity of Src through targeting the inhibitory phosphor-tyrosine527 of Src.
Assuntos
Lipopolissacarídeos/farmacologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Transdução de Sinais/efeitos dos fármacos , Quinases da Família src/metabolismo , Animais , Citocinas/genética , Citocinas/metabolismo , Regulação para Baixo , Inflamação/metabolismo , Inflamação/patologia , Camundongos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Modelos Biológicos , NF-kappa B/metabolismo , Fosforilação/efeitos dos fármacos , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Células RAW 264.7 , Tirosina/metabolismoRESUMO
Breast cancer is a heterogeneous disease and new clinical markers are needed to individualise disease management and therapy further. Alterations in the PI3K/AKT pathway, mainly PIK3CA mutations, have been shown frequently especially in the luminal breast cancer subtypes, suggesting a cross-talk between ER and PI3K/AKT. Aberrant PI3K/AKT signalling has been connected to poor response to anti-oestrogen therapies. In vitro studies have shown protein tyrosine phosphatase, non-receptor type 2 (PTPN2) as a previously unknown negative regulator of the PI3K/AKT pathway. Here, we evaluate possible genomic alterations in the PTPN2 gene and its potential as a new prognostic and treatment predictive marker for endocrine therapy benefit in breast cancer. PTPN2 gene copy number was assessed by real-time PCR in 215 tumour samples from a treatment randomised study consisting of postmenopausal patients diagnosed with stage II breast cancer 1976-1990. Corresponding mRNA expression levels of PTPN2 were evaluated in 86 available samples by the same methodology. Gene copy loss of PTPN2 was detected in 16% (34/215) of the tumours and this was significantly correlated with lower levels of PTPN2 mRNA. PTPN2 gene loss and lower mRNA levels were associated with activation of AKT and a poor prognosis. Furthermore, PTPN2 gene loss was a significant predictive marker of poor benefit from tamoxifen treatment. In conclusion, genomic loss of PTPN2 may be a previously unknown mechanism of PI3K/AKT upregulation in breast cancer. PTPN2 status is a potential new clinical marker of endocrine treatment benefit which could guide further individualised therapies in breast cancer.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Resistencia a Medicamentos Antineoplásicos/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Tamoxifeno/farmacologia , Antineoplásicos Hormonais/farmacologia , Antineoplásicos Hormonais/uso terapêutico , Biomarcadores Tumorais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Feminino , Deleção de Genes , Dosagem de Genes , Expressão Gênica , Humanos , Metástase Linfática , Prognóstico , RNA Mensageiro/genética , Análise de Sobrevida , Tamoxifeno/uso terapêutico , Carga TumoralRESUMO
Loss-of-function variants within the gene locus encoding protein tyrosine phosphatase non-receptor type 2 (PTPN2) are associated with increased risk for Crohn's disease (CD). A disturbed regulation of T helper (Th) cell responses causing loss of tolerance against self- or commensal-derived antigens and an altered intestinal microbiota plays a pivotal role in CD pathogenesis. Loss of PTPN2 in the T-cell compartment causes enhanced induction of Th1 and Th17 cells, but impaired induction of regulatory T cells (Tregs) in several mouse colitis models, namely acute and chronic dextran sodium sulfate colitis, and T-cell transfer colitis models. This results in increased susceptibility to intestinal inflammation and intestinal dysbiosis which is comparable with that observed in CD patients. We detected inflammatory infiltrates in liver, kidney, and skin and elevated autoantibody levels indicating systemic loss of tolerance in PTPN2-deficient animals. CD patients featuring a loss-of-function PTPN2 variant exhibit enhanced Th1 and Th17 cell, but reduced Treg markers when compared with PTPN2 wild-type patients in serum and intestinal tissue samples. Our data demonstrate that dysfunction of PTPN2 results in aberrant T-cell differentiation and intestinal dysbiosis similar to those observed in human CD. Our findings indicate a novel and crucial role for PTPN2 in chronic intestinal inflammation.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Diferenciação Celular , Colite/genética , Colite/imunologia , Disbiose , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Animais , Autoimunidade , Linfócitos T CD4-Positivos/citologia , Diferenciação Celular/genética , Colite/microbiologia , Colite/patologia , Modelos Animais de Doenças , Progressão da Doença , Microbioma Gastrointestinal , Expressão Gênica , Humanos , Doenças Inflamatórias Intestinais/genética , Doenças Inflamatórias Intestinais/imunologia , Doenças Inflamatórias Intestinais/microbiologia , Doenças Inflamatórias Intestinais/patologia , Contagem de Linfócitos , Camundongos , Camundongos Knockout , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Fatores de Transcrição STAT/genética , Fatores de Transcrição STAT/metabolismo , Índice de Gravidade de Doença , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Chronic exposure to UV radiation can contribute to the development of skin cancer by promoting protein-tyrosine kinase (PTK) signaling. Studies show that exposure to UV radiation increases the ligand-independent activation of PTKs and induces protein-tyrosine phosphatase (PTP) inactivation. In the present work, we report that T-cell PTP (TC-PTP) activity is stimulated during the initial response to UVB irradiation, which leads to suppression of keratinocyte cell survival and proliferation via the down-regulation of STAT3 signaling. Our results show that TC-PTP-deficient keratinocyte cell lines expressed a significantly increased level of phosphorylated STAT3 after exposure to low dose UVB. This increase corresponded with increased cell proliferation in TC-PTP-deficient keratinocytes following UVB irradiation. Loss of TC-PTP also reduced UVB-induced apoptosis. Corroborating with these results, overexpression of TC-PTP in keratinocyte cell lines yielded a decrease in phosphorylated STAT3 levels, which corresponded with a significant decrease in cell proliferation in response to low dose UVB. We demonstrate that TC-PTP activity was increased upon UVB exposure, and overexpression of TC-PTP in keratinocyte cell lines further increased its activity in the presence of UVB. Treatment of TC-PTP-deficient keratinocytes with the STAT3 inhibitor STA21 significantly reduced cell viability following UVB exposure in comparison with untreated TC-PTP-deficient keratinocytes, confirming that the effect of TC-PTP on cell viability is mediated by STAT3 dephosphorylation. Combined, our results indicate that UVB-mediated activation of TC-PTP plays an important role in the STAT3-dependent regulation of keratinocyte cell proliferation and survival. Furthermore, these results suggest that TC-PTP may be a novel potential target for the prevention of UVB-induced skin cancer.
Assuntos
Queratinócitos/efeitos da radiação , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Fator de Transcrição STAT3/genética , Adenoviridae/genética , Animais , Apoptose/efeitos da radiação , Caspase 3/genética , Caspase 3/metabolismo , Linhagem Celular Transformada , Proliferação de Células/efeitos da radiação , Sobrevivência Celular/efeitos da radiação , Ativação Enzimática/efeitos da radiação , Regulação da Expressão Gênica , Vetores Genéticos , Queratinócitos/citologia , Queratinócitos/enzimologia , Camundongos , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Fator de Transcrição STAT3/antagonistas & inibidores , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais , Raios UltravioletaRESUMO
Hepatic insulin resistance is a key contributor to the pathogenesis of obesity and type 2 diabetes (T2D). Paradoxically, the development of insulin resistance in the liver is not universal, but pathway selective, such that insulin fails to suppress gluconeogenesis but promotes lipogenesis, contributing to the hyperglycemia, steatosis, and hypertriglyceridemia that underpin the deteriorating glucose control and microvascular complications in T2D. The molecular basis for the pathway-specific insulin resistance remains unknown. Here we report that oxidative stress accompanying obesity inactivates protein-tyrosine phosphatases (PTPs) in the liver to activate select signaling pathways that exacerbate disease progression. In obese mice, hepatic PTPN2 (TCPTP) inactivation promoted lipogenesis and steatosis and insulin-STAT-5 signaling. The enhanced STAT-5 signaling increased hepatic IGF-1 production, which suppressed central growth hormone release and exacerbated the development of obesity and T2D. Our studies define a mechanism for the development of selective insulin resistance with wide-ranging implications for diseases characterized by oxidative stress.
Assuntos
Insulina/metabolismo , Fígado/metabolismo , Estresse Oxidativo , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Fator de Transcrição STAT5/metabolismo , Animais , Células Cultivadas , Dieta Hiperlipídica , Feminino , Glutationa Peroxidase/deficiência , Glutationa Peroxidase/genética , Glutationa Peroxidase/metabolismo , Hormônio do Crescimento/metabolismo , Hepatócitos/citologia , Hepatócitos/metabolismo , Insulina/farmacologia , Fator de Crescimento Insulin-Like I/metabolismo , Fígado/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/metabolismo , Obesidade/patologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Espécies Reativas de Oxigênio/metabolismo , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/metabolismo , Fator de Transcrição STAT5/genética , Transdução de Sinais/efeitos dos fármacos , Glutationa Peroxidase GPX1RESUMO
BACKGROUND: Acute pancreatitis (AP) is a common clinical problem whose incidence has been progressively increasing in recent years. Onset of the disease is trigged by intra-acinar cell activation of digestive enzyme zymogens that induce autodigestion, release of pro-inflammatory cytokines and acinar cell injury. T-cell protein tyrosine phosphatase (TCPTP) is implicated in inflammatory signaling but its significance in AP remains unclear. RESULTS: In this study we assessed the role of pancreatic TCPTP in cerulein-induced AP. TCPTP expression was increased at the protein and messenger RNA levels in the early phase of AP in mice and rats. To directly determine whether TCPTP may have a causal role in AP we generated mice with pancreatic TCPTP deletion (panc-TCPTP KO) by crossing TCPTP floxed mice with Pdx1-Cre transgenic mice. Amylase and lipase levels were lower in cerulein-treated panc-TCPTP KO mice compared with controls. In addition, pancreatic mRNA and serum concentrations of the inflammatory cytokines TNFα and IL-6 were lower in panc-TCPTP KO mice. At the molecular level, panc-TCPTP KO mice exhibited enhanced cerulein-induced STAT3 Tyr705 phosphorylation accompanied by a decreased cerulein-induced NF-κB inflammatory response, and decreased ER stress and cell death. CONCLUSION: These findings revealed a novel role for pancreatic TCPTP in the progression of cerulein-induced AP.
Assuntos
Pancreatite Necrosante Aguda/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Amilases/sangue , Animais , Ceruletídeo/toxicidade , Interleucina-6/sangue , Lipase/sangue , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/metabolismo , Pancreatite Necrosante Aguda/induzido quimicamente , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Fator de Transcrição STAT3/metabolismo , Fator de Necrose Tumoral alfa/sangueRESUMO
When the peripheral T-cell pool is depleted, T cells undergo homoeostatic expansion. This expansion is reliant on the recognition of self-antigens and/or cytokines, in particular interleukin-7. The T cell-intrinsic mechanisms that prevent excessive homoeostatic T-cell responses and consequent overt autoreactivity remain poorly defined. Here we show that protein tyrosine phosphatase N2 (PTPN2) is elevated in naive T cells leaving the thymus to restrict homoeostatic T-cell proliferation and prevent excess responses to self-antigens in the periphery. PTPN2-deficient CD8(+) T cells undergo rapid lymphopenia-induced proliferation (LIP) when transferred into lymphopenic hosts and acquire the characteristics of antigen-experienced effector T cells. The enhanced LIP is attributed to elevated T-cell receptor-dependent, but not interleukin-7-dependent responses, results in a skewed T-cell receptor repertoire and the development of autoimmunity. Our results identify a major mechanism by which homoeostatic T-cell responses are tuned to prevent the development of autoimmune and inflammatory disorders.
Assuntos
Linfócitos T CD8-Positivos/patologia , Proliferação de Células/fisiologia , Linfopenia/patologia , Linfopenia/fisiopatologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/fisiologia , Animais , Autoimunidade/fisiologia , Células Cultivadas , Modelos Animais de Doenças , Feminino , Homeostase/fisiologia , Técnicas In Vitro , Interleucina-7/fisiologia , Linfopenia/etiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Efeitos da Radiação , Timo/patologiaRESUMO
OBJECTIVE: T cell protein tyrosine phosphatase (TC-PTP) is an important regulator of hematopoiesis and cytokine signaling. Recently, several genome-wide association studies have identified single-nucleotide polymorphisms (SNPs) in the locus of TC-PTP that are associated with rheumatoid arthritis and juvenile idiopathic arthritis, among other autoimmune diseases. The aim of this study was to evaluate the effect of TC-PTP deficiency on the bone and joint environment using a knockout mouse model. METHODS: Radiographic and micro-computed tomography analyses were performed on femurs of 3-week-old mice. In addition, the femorotibial joints were assessed by histology, flow cytometry, and cytokine detection. RESULTS: Deficiency of TC-PTP resulted in decreased bone volume as well as an increase in osteoclast density within the mouse femurs. In addition, synovitis, characterized by infiltration of mixed inflammatory cell types and proinflammatory cytokines, developed in the knee joints of TC-PTP(-/-) mice. CONCLUSION: These findings demonstrate that loss of TC-PTP expression results in synovitis with several hallmarks of inflammatory arthritis. The inflammatory environment observed in the knee joints of TC-PTP(-/-) mice differs from the systemic inflammation previously described in these mice and merits further research into the role of TC-PTP in the synovium. Furthermore, the results support recently described associations between SNPs in the TC-PTP locus and arthritis incidence.
Assuntos
Reabsorção Óssea/enzimologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Sinovite/enzimologia , Linfócitos T/enzimologia , Animais , Reabsorção Óssea/patologia , Reabsorção Óssea/fisiopatologia , Cartilagem Articular , Contagem de Células , Feminino , Fêmur/diagnóstico por imagem , Fêmur/metabolismo , Fêmur/patologia , Endogamia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Osteoblastos/patologia , Osteoclastos/patologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Radiografia , Joelho de Quadrúpedes/metabolismo , Joelho de Quadrúpedes/patologia , Sinovite/patologia , Sinovite/fisiopatologia , Linfócitos T/patologiaRESUMO
AIMS/HYPOTHESIS: Insulin activates insulin receptor protein tyrosine kinase and downstream phosphatidylinositol-3-kinase (PI3K)/Akt signalling in muscle to promote glucose uptake. The insulin receptor can serve as a substrate for the protein tyrosine phosphatase (PTP) 1B and T cell protein tyrosine phosphatase (TCPTP), which share a striking 74% sequence identity in their catalytic domains. PTP1B is a validated therapeutic target for the alleviation of insulin resistance in type 2 diabetes. PTP1B dephosphorylates the insulin receptor in liver and muscle to regulate glucose homeostasis, whereas TCPTP regulates insulin receptor signalling and gluconeogenesis in the liver. In this study we assessed for the first time the role of TCPTP in the regulation of insulin receptor signalling in muscle. METHODS: We generated muscle-specific TCPTP-deficient (Mck-Cre;Ptpn2(lox/lox)) mice (Mck, also known as Ckm) and assessed the impact on glucose homeostasis and muscle insulin receptor signalling in chow-fed versus high-fat-fed mice. RESULTS: Blood glucose and insulin levels, insulin and glucose tolerance, and insulin-induced muscle insulin receptor activation and downstream PI3K/Akt signalling remained unaltered in chow-fed Mck-Cre;Ptpn2(lox/lox) versus Ptpn2(lox/lox) mice. In addition, body weight, adiposity, energy expenditure, insulin sensitivity and glucose homeostasis were not altered in high-fat-fed Mck-Cre;Ptpn2(lox/lox) versus Ptpn2(lox/lox) mice. CONCLUSIONS/INTERPRETATION: These results indicate that TCPTP deficiency in muscle has no effect on insulin signalling and glucose homeostasis, and does not prevent high-fat diet-induced insulin resistance. Thus, despite their high degree of sequence identity, PTP1B and TCPTP contribute differentially to insulin receptor regulation in muscle. Our results are consistent with the notion that these two highly related PTPs make distinct contributions to insulin receptor regulation in different tissues.
Assuntos
Glucose/metabolismo , Músculos/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/fisiologia , Animais , Diabetes Mellitus Tipo 2/sangue , Teste de Tolerância a Glucose , Homeostase , Insulina/metabolismo , Resistência à Insulina , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Receptor de Insulina/metabolismo , Transdução de Sinais , Fatores de Tempo , Distribuição TecidualRESUMO
Many autoimmune diseases exhibit familial aggregation, indicating that they have genetic determinants. Single nucleotide polymorphisms in PTPN2, which encodes T cell protein tyrosine phosphatase (TCPTP), have been linked with the development of several autoimmune diseases, including type 1 diabetes and Crohn's disease. In this study, we have identified TCPTP as a key negative regulator of TCR signaling, which might explain the association of PTPN2 SNPs with autoimmune disease. We found that TCPTP dephosphorylates and inactivates Src family kinases to regulate T cell responses. Using T cell-specific TCPTP-deficient mice, we established that TCPTP attenuates T cell activation and proliferation in vitro and blunts antigen-induced responses in vivo. TCPTP deficiency lowered the in vivo threshold for TCR-dependent CD8(+) T cell proliferation. Consistent with this, T cell-specific TCPTP-deficient mice developed widespread inflammation and autoimmunity that was transferable to wild-type recipient mice by CD8(+) T cells alone. This autoimmunity was associated with increased serum levels of proinflammatory cytokines and anti-nuclear antibodies, T cell infiltrates in non-lymphoid tissues, and liver disease. These data indicate that TCPTP is a critical negative regulator of TCR signaling that sets the threshold for TCR-induced naive T cell responses to prevent autoimmune and inflammatory disorders arising.
Assuntos
Doenças Autoimunes/etiologia , Tolerância Imunológica/imunologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/fisiologia , Receptores de Antígenos de Linfócitos T/imunologia , Subpopulações de Linfócitos T/enzimologia , Animais , Anticorpos Antinucleares/biossíntese , Doenças Autoimunes/enzimologia , Doenças Autoimunes/imunologia , Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/transplante , Inflamação/sangue , Inflamação/genética , Inflamação/imunologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Fosforilação , Processamento de Proteína Pós-Traducional , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Quimera por Radiação , Transdução de Sinais/imunologia , Subpopulações de Linfócitos T/imunologia , Timócitos/patologia , Proteína-Tirosina Quinase ZAP-70/fisiologia , Quinases da Família src/metabolismoRESUMO
In obesity, anorectic responses to leptin are diminished, giving rise to the concept of "leptin resistance." Increased expression of protein tyrosine phosphatase 1B (PTP1B) has been associated with the attenuation of leptin signaling and development of cellular leptin resistance. Here we report that hypothalamic levels of the tyrosine phosphatase TCPTP are also elevated in obesity to attenuate the leptin response. We show that mice that lack TCPTP in neuronal cells have enhanced leptin sensitivity and are resistant to high-fat-diet-induced weight gain and the development of leptin resistance. Also, intracerebroventricular administration of a TCPTP inhibitor enhances leptin signaling and responses in mice. Moreover, the combined deletion of TCPTP and PTP1B in neuronal cells has additive effects in the prevention of diet-induced obesity. Our results identify TCPTP as a critical negative regulator of hypothalamic leptin signaling and causally link elevated TCPTP to the development of cellular leptin resistance in obesity.
Assuntos
Hipotálamo/metabolismo , Leptina/metabolismo , Neurônios/metabolismo , Obesidade/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Transdução de Sinais , Animais , Glicemia/análise , Composição Corporal/efeitos dos fármacos , Dieta Hiperlipídica , Inibidores Enzimáticos/farmacologia , Feminino , Expressão Gênica , Hipotálamo/citologia , Infusões Intraventriculares , Insulina/sangue , Masculino , Camundongos , Camundongos Transgênicos , Neurônios/citologia , Obesidade/genética , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/antagonistas & inibidores , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Receptores para Leptina/metabolismo , Técnicas de Cultura de TecidosRESUMO
OBJECTIVE: Insulin-induced phosphatidylinositol 3-kinase (PI3K)/Akt signaling and interleukin-6 (IL-6)-instigated JAK/STAT3-signaling pathways in the liver inhibit the expression of gluconeogenic genes to decrease hepatic glucose output. The insulin receptor (IR) and JAK1 tyrosine kinases and STAT3 can serve as direct substrates for the T-cell protein tyrosine phosphatase (TCPTP). Homozygous TCPTP-deficiency results in perinatal lethality prohibiting any informative assessment of TCPTP's role in glucose homeostasis. Here we have used Ptpn2+/- mice to investigate TCPTP's function in glucose homeostasis. RESEARCH DESIGN AND METHODS: We analyzed insulin sensitivity and gluconeogenesis in chow versus high-fat-fed (HFF) Ptpn2+/- and Ptpn2+/+ mice and insulin and IL-6 signaling and gluconeogenic gene expression in Ptpn2+/- and Ptpn2+/+ hepatocytes. RESULTS: HFF Ptpn2+/- mice exhibited lower fasted blood glucose and decreased hepatic glucose output as determined in hyperinsulinemic euglycemic clamps and by the decreased blood glucose levels in pyruvate tolerance tests. The reduced hepatic glucose output coincided with decreased expression of the gluconeogenic genes G6pc and Pck1 and enhanced hepatic STAT3 phosphorylation and PI3K/Akt signaling in the fasted state. Insulin-induced IR-beta-subunit Y1162/Y1163 phosphorylation and PI3K/Akt signaling and IL-6-induced STAT3 phosphorylation were also enhanced in isolated Ptpn2+/- hepatocytes. The increased insulin and IL-6 signaling resulted in enhanced suppression of G6pc and Pck1 mRNA. CONCLUSIONS: Liver TCPTP antagonises both insulin and STAT3 signaling pathways to regulate gluconeogenic gene expression and hepatic glucose output.