RESUMO
The process of erythroid differentiation is orchestrated at the molecular level by a complex network of transcription factors. Erythroid Krüppel-like factor (EKLF/KLF1) is a master erythroid gene regulator that directly regulates most aspects of terminal erythroid differentiation. However, the underlying regulatory mechanisms of EKLF protein stability are still largely unknown. In this study, we identified Vacuolar protein sorting 37 C (VPS37C), a core subunit of the Endosomal sorting complex required for transport-I (ESCRT-I) complex, as an essential regulator of EKLF stability. Our study showed that VPS37C interacts with EKLF and prevents K48-linked polyubiquitination of EKLF and proteasome-mediated EKLF degradation, thus enhancing EKLF protein stability and transcriptional activity. VPS37C overexpression in murine erythroleukemia (MEL) cells promotes hexamethylene bisacetamide (HMBA)-induced erythroid differentiation manifested by up-regulating erythroid-specific EKLF target genes and increasing benzidine-positive cells. In contrast, VPS37C knockdown inhibits HMBA-induced MEL cell erythroid differentiation. Particularly, the restoration of EKLF expression in VPS37C-knockdown MEL cells reverses erythroid-specific gene expression and hemoglobin production. Collectively, our study demonstrated VPS37C is a novel regulator of EKLF ubiquitination and degradation, which plays a positive role in erythroid differentiation of MEL cells by enhancing EKLF protein stability.
Assuntos
Fatores de Transcrição Kruppel-Like , Proteína C , Animais , Camundongos , Proteína C/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Diferenciação Celular/genética , Transporte Proteico , Células Eritroides/metabolismoRESUMO
Erythropoiesis is a complex multistage process that involves differentiation of early erythroid progenitors to enucleated mature red blood cells, in which lineage-specific transcription factors play essential roles. Erythroid Krüppel-like factor (EKLF/KLF1) is a pleiotropic erythroid transcription factor that is required for the proper maturation of the erythroid cells, whose expression and activation are tightly controlled in a temporal and differentiation stage-specific manner. Here, we uncover a novel role of G-protein pathway suppressor 2 (GPS2), a subunit of the nuclear receptor corepressor/silencing mediator of retinoic acid and thyroid hormone receptor corepressor complex, in erythrocyte differentiation. Our study demonstrates that knockdown of GPS2 significantly suppresses erythroid differentiation of human CD34+ cells cultured in vitro and xenotransplanted in nonobese diabetic/severe combined immunodeficiency/interleukin-2 receptor γ-chain null mice. Moreover, global deletion of GPS2 in mice causes impaired erythropoiesis in the fetal liver and leads to severe anemia. Flow cytometric analysis and Wright-Giemsa staining show a defective differentiation at late stages of erythropoiesis in Gps2-/- embryos. Mechanistically, GPS2 interacts with EKLF and prevents proteasome-mediated degradation of EKLF, thereby increasing EKLF stability and transcriptional activity. Moreover, we identify the amino acids 191-230 region in EKLF protein, responsible for GPS2 binding, that is highly conserved in mammals and essential for EKLF protein stability. Collectively, our study uncovers a previously unknown role of GPS2 as a posttranslational regulator that enhances the stability of EKLF protein and thereby promotes erythroid differentiation.
Assuntos
Eritropoese/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Fatores de Transcrição Kruppel-Like/fisiologia , Sequência de Aminoácidos , Animais , Células Cultivadas , Sequência Conservada , Células Precursoras Eritroides/citologia , Técnicas de Silenciamento de Genes , Transplante de Células-Tronco Hematopoéticas , Humanos , Subunidade gama Comum de Receptores de Interleucina/deficiência , Peptídeos e Proteínas de Sinalização Intracelular/biossíntese , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Peptídeos e Proteínas de Sinalização Intracelular/genética , Fatores de Transcrição Kruppel-Like/antagonistas & inibidores , Fatores de Transcrição Kruppel-Like/química , Fígado/embriologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos SCID , Mapeamento de Interação de Proteínas , Processamento de Proteína Pós-Traducional , Estabilidade Proteica , Proteólise , Interferência de RNA , RNA Interferente Pequeno/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transcrição Gênica , Transplante Heterólogo , Ubiquitinação , Regulação para CimaRESUMO
During human erythroid maturation, Hsp70 translocates into the nucleus and protects GATA-1 from caspase-3 cleavage. Failure of Hsp70 to localize to the nucleus was found in Myelodysplastic syndrome (MDS) erythroblasts and can induce dyserythropoiesis, with arrest of maturation and death of erythroblasts. However, the mechanism of the nuclear trafficking of Hsp70 in erythroblasts remains unknown. Here, we found the hematopoietic transcriptional regulator, EDAG, to be a novel binding partner of Hsp70 that forms a protein complex with Hsp70 and GATA-1 during human normal erythroid differentiation. EDAG overexpression blocked the cytoplasmic translocation of Hsp70 induced by EPO deprivation, inhibited GATA-1 degradation, thereby promoting erythroid maturation in an Hsp70-dependent manner. Furthermore, in myelodysplastic syndrome (MDS) patients with dyserythropoiesis, EDAG is dramatically down-regulated, and forced expression of EDAG has been found to restore the localization of Hsp70 in the nucleus and elevate the protein level of GATA-1 to a significant extent. In addition, EDAG rescued the dyserythropoiesis of MDS patients by increasing erythroid differentiation and decreasing cell apoptosis. This study demonstrates the molecular mechanism of Hsp70 nuclear sustaining during erythroid maturation and establishes that EDAG might be a suitable therapeutic target for dyserythropoiesis in MDS patients.
Assuntos
Núcleo Celular/metabolismo , Eritroblastos/metabolismo , Eritropoese/fisiologia , Proteínas de Choque Térmico HSP70/metabolismo , Síndromes Mielodisplásicas/metabolismo , Proteínas Nucleares/metabolismo , Apoptose/fisiologia , Caspase 3/metabolismo , Diferenciação Celular/fisiologia , Células Cultivadas , Citoplasma/metabolismo , Regulação da Expressão Gênica/fisiologia , Doenças Hematológicas/metabolismo , HumanosRESUMO
The nucleotide-binding domain and leucine-rich repeat-containing family pyrin domain containing 3 (NLRP3) inflammasome is involved in various acute and chronic liver diseases, however, it is not clear whether NLRP3 contributes to d-Galactosamine (D-GalN) plus lipopolysaccharide (LPS)-induced acute liver failure (ALF). This study aims to investigate the role of NLRP3 inflammasome in D-GalN/LPS-induced fatal hepatitis. We found that Nlrp3-/- and WT mice showed similar mortality against a lethal dose of D-GalN/LPS treatment. Serum ALT and AST levels, as well as liver necrosis area and hepatocyte apoptosis, were not significantly different between Nlrp3-/- and WT mice at 6 h after D-GalN/LPS injection. Moreover, the numbers of intrahepatic F4/80+ cells and Ly6G+ cells were comparable in two genotype mice following D-GalN/LPS treatment. Besides, Nlrp3-/- mice had reduced IL-1ß levels but similar TNF-α, IL-6, and MCP-1 levels compared with WT mice upon D-GalN/LPS administration. Our findings revealed that NLRP3 ablation does not protect mice from D-GalN/LPS-induced fatal hepatitis and has a marginal effect on intrahepatic inflammatory response upon D-GalN/LPS treatment. This suggests that NLRP3 inflammasome does not appear to be a major contributor to D-GalN/LPS-induced ALF.
Assuntos
Falência Hepática Aguda/etiologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/fisiologia , Animais , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/patologia , Galactosamina , Inflamassomos/metabolismo , Inflamassomos/fisiologia , Interleucina-1beta/sangue , Lipopolissacarídeos , Falência Hepática Aguda/induzido quimicamente , Falência Hepática Aguda/imunologia , Falência Hepática Aguda/metabolismo , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Fator de Necrose Tumoral alfa/sangueRESUMO
Toll-like receptor-5 (TLR5) signaling regulates the immune privileged status of the liver and is involved in hepatic immune disorders. However, the role of TLR5 has not yet been investigated in experimental models of concanavalin A (Con A)-mediated liver injury. Here, we show that TLR5 is highly up-regulated in the hepatic mononuclear cells of mice during Con A-induced hepatitis. Increased mortality and liver histopathology of TLR5-deficient mice correlated with excessive production of proinflammatory cytokines, suggesting that TLR5 knockout mice were more susceptible to Con A-induced hepatitis. We also report that administration of CBLB502, an exogenous TLR5 agonist, substantially alleviated Con A-mediated hepatitis in wild-type mice as shown by increased survival rates, reduced aminotransferase and proinflammatory cytokine production, impaired lymphocyte infiltration, and ameliorated hepatocyte necrosis and/or apoptosis. Mechanistic studies revealed that CBLB502 acts as a negative regulator in limiting T-cell/natural killer T-cell activity and cytokine production in the Con A-hepatitis model. Bone marrow transplantation experiments showed that TLR5 in bone marrow-derived cells contributed to the hepatoprotective efficacy of CBLB502 against Con A-induced liver injury. Moreover, interleukin-6 elevation induced by CBLB502 is an important protective factor against Con A-induced liver injury. In addition, we demonstrate that CBLB502 suppresses α-galactosylceramide-induced natural killer T cell-dependent inflammatory liver injury. CONCLUSION: The TLR5 signaling pathway plays an important role in T cell-mediated hepatic injury and may be exploited for therapeutic treatment of inflammatory liver diseases. (Hepatology 2017;65:2059-2073).
Assuntos
Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Concanavalina A/toxicidade , Células T Matadoras Naturais/imunologia , Peptídeos/farmacologia , Receptor 5 Toll-Like/metabolismo , Animais , Biópsia por Agulha , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/sangue , Doença Hepática Induzida por Substâncias e Drogas/mortalidade , Concanavalina A/farmacologia , Citocinas/metabolismo , Modelos Animais de Doenças , Citometria de Fluxo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Imuno-Histoquímica , Mediadores da Inflamação/sangue , Estimativa de Kaplan-Meier , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Distribuição Aleatória , Valores de Referência , Transdução de Sinais , Taxa de Sobrevida , Receptor 5 Toll-Like/efeitos dos fármacosRESUMO
Hepatocyte nuclear factor-1 alpha (HNF1α) exerts important effects on gene expression in multiple tissues. Several studies have directly or indirectly supported the role of phosphorylation processes in the activity of HNF1α. However, the molecular mechanism of this phosphorylation remains largely unknown. Using microcapillary liquid chromatography MS/MS and biochemical assays, we identified a novel phosphorylation site in HNF1α at Ser249. We also found that the ATM protein kinase phosphorylated HNF1α at Ser249 in vitro in an ATM-dependent manner and that ATM inhibitor KU55933 treatment inhibited phosphorylation of HNF1α at Ser249 in vivo. Coimmunoprecipitation assays confirmed the association between HNF1α and ATM. Moreover, ATM enhanced HNF1α transcriptional activity in a dose-dependent manner, whereas the ATM kinase-inactive mutant did not. The use of KU55933 confirmed our observation. Compared with wild-type HNF1α, a mutation in Ser249 resulted in a pronounced decrease in HNF1α transactivation, whereas no dominant-negative effect was observed. The HNF1αSer249 mutant also exhibited normal nuclear localization but decreased DNA-binding activity. Accordingly, the functional studies of HNF1αSer249 mutant revealed a defect in glucose metabolism. Our results suggested that ATM regulates the activity of HNF1α by phosphorylation of serine 249, particularly in glucose metabolism, which provides valuable insights into the undiscovered mechanisms of ATM in the regulation of glucose homeostasis.
Assuntos
Proteínas Mutadas de Ataxia Telangiectasia/genética , Glucose/metabolismo , Fator 1-alfa Nuclear de Hepatócito/metabolismo , Ativação Transcricional/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Linhagem Celular , Proteínas de Ligação a DNA , Glucose/genética , Fator 1-alfa Nuclear de Hepatócito/genética , Humanos , Morfolinas/farmacologia , Mutação , Fosforilação/efeitos dos fármacos , Regiões Promotoras Genéticas , Pironas/farmacologia , Serina/genética , Ativação Transcricional/efeitos dos fármacosRESUMO
BACKGROUND & AIMS: Hepassocin (HPS) is a hepatotrophic growth factor that specifically stimulates hepatocyte proliferation and promotes liver regeneration after liver damage. In this paper, zebrafish were used to investigate the role of HPS in liver development. METHODS AND RESULTS: During zebrafish development, HPS expression is enriched in liver throughout hepatogenesis. Knockdown of HPS using its specific morpholino leads to a smaller liver phenotype. Further results showed that the HPS knockdown has no effect on the expression of the early endoderm marker gata6 and early hepatic marker hhex. In addition, results showed that the smaller-liver phenotype in HPS morphants was caused by suppression of cell proliferation, not induction of cell apoptosis. CONCLUSIONS: Current findings indicated that HPS is essential to the later stages of development in vertebrate liver organogenesis.
Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Fígado/embriologia , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra/embriologia , Animais , Proliferação de Células , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Silenciamento de Genes , Hepatócitos/citologia , Hepatócitos/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Fígado/metabolismo , Morfolinos/genética , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genéticaRESUMO
Erythroid differentiation-associated gene (EDAG) has been considered to be a transcriptional regulator that controls hematopoietic cell differentiation, proliferation, and apoptosis. The role of EDAG in erythroid differentiation of primary erythroid progenitor cells and in vivo remains unknown. In this study, we found that EDAG is highly expressed in CMPs and MEPs and upregulated during the erythroid differentiation of CD34(+) cells following erythropoietin (EPO) treatment. Overexpression of EDAG induced erythroid differentiation of CD34(+) cells in vitro and in vivo using immunodeficient mice. Conversely, EDAG knockdown reduced erythroid differentiation in EPO-treated CD34(+) cells. Detailed mechanistic analysis suggested that EDAG forms complex with GATA1 and p300 and increases GATA1 acetylation and transcriptional activity by facilitating the interaction between GATA1 and p300. EDAG deletion mutants lacking the binding domain with GATA1 or p300 failed to enhance erythroid differentiation, suggesting that EDAG regulates erythroid differentiation partly through forming EDAG/GATA1/p300 complex. In the presence of the specific inhibitor of p300 acetyltransferase activity, C646, EDAG was unable to accelerate erythroid differentiation, indicating an involvement of p300 acetyltransferase activity in EDAG-induced erythroid differentiation. ChIP-PCR experiments confirmed that GATA1 and EDAG co-occupy GATA1-targeted genes in primary erythroid cells and in vivo. ChIP-seq was further performed to examine the global occupancy of EDAG during erythroid differentiation and a total of 7,133 enrichment peaks corresponding to 3,847 genes were identified. Merging EDAG ChIP-Seq and GATA1 ChIP-Seq datasets revealed that 782 genes overlapped. Microarray analysis suggested that EDAG knockdown selectively inhibits GATA1-activated target genes. These data provide novel insights into EDAG in regulation of erythroid differentiation.
Assuntos
Diferenciação Celular/fisiologia , Proteína p300 Associada a E1A/metabolismo , Fator de Transcrição GATA1/metabolismo , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/citologia , Proteínas Nucleares/metabolismo , Acetilação , Animais , Western Blotting , Separação Celular , Células Eritroides/citologia , Células Eritroides/metabolismo , Feminino , Citometria de Fluxo , Células-Tronco Hematopoéticas/metabolismo , Xenoenxertos , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Análise de Sequência com Séries de Oligonucleotídeos , TranscriptomaRESUMO
14-3-3 proteins regulate numerous cellular processes through interaction with a variety of proteins, and have been identified as HNF1α binding partner by mass spectrometry analysis in our previous study. In the present study, the interaction between 14-3-3ζ and HNF1α has been further validated by in vivo and in vitro assays. Moreover, we have found that overexpression of 14-3-3ζ potentiated the transcriptional activity of HNF1α in cultured cells, and silencing of 14-3-3ζ by RNA interference in HepG2 cells specifically affected the HNF1α-dependent gene expression. Furthermore, we have demonstrated that 14-3-3ζ is recruited to endogenous HNF1α responsive promoters and enhances HNF1α binding to its cognate DNA sequences. In addition, we have also provided evidence that the association between HNF1α and 14-3-3ζ is phosphorylation-dependent. Taken together, these results suggest that 14-3-3ζ may be an endogenous physiologic regulator of HNF1α.
Assuntos
Proteínas 14-3-3/metabolismo , DNA/metabolismo , Fator 1-alfa Nuclear de Hepatócito/metabolismo , Ativação Transcricional , Sequência de Bases , Linhagem Celular Tumoral , Primers do DNA , Humanos , Fosforilação , Ligação Proteica , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Polyglutamine diseases are a group of neurodegenerative disorders caused by expansion of a CAG repeat that encodes polyglutamine in each respective disease gene. The transcription factor THAP11, a member of THAP family, is involved in cell growth, ES cell pluripotency and embryogenesis. Previous studies suggest that THAP11 protein contains a 29-residue repeat polyglutamine motif and the number of polyglutamine ranges from 20 to 41 in Indian population. We have investigated the CAG numbers at the THAP11 locus in normal individuals and neurodegenerative disease patients of Chinese Han population and a 38Q expansion (THAP11(38Q)) was found in patients. Using fluorescence confocal-based cell imaging, THAP11(38Q) protein formed intranuclear inclusions easier than THAP11(29Q) in PC12 cells. Enhanced toxicity was investigated in THAP11(38Q)-expressing cells by growth inhibition and G0/G1 arrest. CREB-mediated transcription activity was inhibited by THAP11(38Q). The transcription factor, TBP, coactivator CBP, and chaperon protein, HSP70, could be recruited to THAP11(38Q). These results indicate that expansion of the polyglutamine in THAP11 forms intracellular aggregation and is toxic in PC12 cells, suggesting a putative role of THAP11 in polyglutamine disease.
Assuntos
Corpos de Inclusão Intranuclear/patologia , Peptídeos/genética , Proteínas Repressoras/genética , Ataxias Espinocerebelares/genética , Animais , Linhagem Celular , Proliferação de Células/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/antagonistas & inibidores , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Pontos de Checagem da Fase G1 do Ciclo Celular , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Células PC12 , Fragmentos de Peptídeos/metabolismo , Polimorfismo Genético/genética , Ratos , Sialoglicoproteínas/metabolismo , Proteína de Ligação a TATA-Box/metabolismoRESUMO
G protein pathway suppressor 2 (GPS2) has been shown to play a pivotal role in human and mouse definitive erythropoiesis in an EKLF-dependent manner. However, whether GPS2 affects human primitive erythropoiesis is still unknown. This study demonstrated that GPS2 positively regulates erythroid differentiation in K562 cells, which have a primitive erythroid phenotype. Overexpression of GPS2 promoted hemin-induced hemoglobin synthesis in K562 cells as assessed by the increased percentage of benzidine-positive cells and the deeper red coloration of the cell pellets. In contrast, knockdown of GPS2 inhibited hemin-induced erythroid differentiation of K562 cells. GPS2 overexpression also enhanced erythroid differentiation of K562 cells induced by cytosine arabinoside (Ara-C). GPS2 induced hemoglobin synthesis by increasing the expression of globin and ALAS2 genes, either under steady state or upon hemin treatment. Promotion of erythroid differentiation of K562 cells by GPS2 mainly relies on NCOR1, as knockdown of NCOR1 or lack of the NCOR1-binding domain of GPS2 potently diminished the promotive effect. Thus, our study revealed a previously unknown role of GPS2 in regulating human primitive erythropoiesis in K562 cells.
Assuntos
Diferenciação Celular , Eritropoese , Hemina , Leucemia Eritroblástica Aguda , Correpressor 1 de Receptor Nuclear , Humanos , Células K562 , Eritropoese/genética , Leucemia Eritroblástica Aguda/patologia , Leucemia Eritroblástica Aguda/metabolismo , Leucemia Eritroblástica Aguda/genética , Correpressor 1 de Receptor Nuclear/metabolismo , Correpressor 1 de Receptor Nuclear/genética , Hemina/farmacologia , Células Eritroides/metabolismo , Células Eritroides/citologia , 5-Aminolevulinato Sintetase/genética , 5-Aminolevulinato Sintetase/metabolismo , Hemoglobinas/metabolismo , Técnicas de Silenciamento de Genes , Peptídeos e Proteínas de Sinalização IntracelularRESUMO
BRISC (BRCC3 isopeptidase complex) is a deubiquitinating enzyme that has been linked with inflammatory processes, but its role in liver diseases and the underlying mechanism are unknown. Here, we investigated the pathophysiological role of BRISC in acute liver failure using a mice model induced by D-galactosamine (D-GalN) plus lipopolysaccharide (LPS). We found that the expression of BRISC components was dramatically increased in kupffer cells (KCs) upon LPS treatment in vitro or by the injection of LPS in D-GalN-sensitized mice. D-GalN plus LPS-induced liver damage and mortality in global BRISC-null mice were markedly attenuated, which was accompanied by impaired hepatocyte death and hepatic inflammation response. Constantly, treatment with thiolutin, a potent BRISC inhibitor, remarkably alleviated D-GalN/LPS-induced liver injury in mice. By using bone marrow-reconstituted chimeric mice and cell-specific BRISC-deficient mice, we demonstrated that KCs are the key effector cells responsible for protection against D-GalN/LPS-induced liver injury in BRISC-deficient mice. Mechanistically, we found that hepatic and circulating levels of TNF-α, IL-6, MCP-1, and IL-1ß, as well as TNF-α- and MCP-1-producing KCs, in BRISC-deleted mice were dramatically decreased as early as 1 h after D-GalN/LPS challenge, which occurred prior to the elevation of the liver injury markers. Moreover, LPS-induced proinflammatory cytokines production in KCs was significantly diminished by BRISC deficiency in vitro, which was accompanied by potently attenuated NF-κB activation. Restoration of NF-κB activation by two small molecular activators of NF-κB p65 effectively reversed the suppression of cytokines production in ABRO1-deficient KCs by LPS. In conclusion, BRISC is required for optimal activation of NF-κB-mediated proinflammatory cytokines production in LPS-treated KCs and contributes to acute liver injury. This study opens the possibility to develop new strategies for the inhibition of KCs-driven inflammation in liver diseases.
Assuntos
Doença Hepática Crônica Induzida por Substâncias e Drogas , Doença Hepática Induzida por Substâncias e Drogas , Animais , Camundongos , NF-kappa B/metabolismo , Lipopolissacarídeos/farmacologia , Células de Kupffer/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Fígado/metabolismo , Inflamação/metabolismo , Galactosamina , Doença Hepática Induzida por Substâncias e Drogas/genética , Doença Hepática Induzida por Substâncias e Drogas/metabolismoRESUMO
The antioxidant response elements (ARE) are a cis-acting enhancer sequence located in regulatory regions of antioxidant and detoxifying genes. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a member of the Cap 'n' Collar family of transcription factors that binds to the ARE and regulates the transcription of specific ARE-containing genes. Under oxidative stress, Nrf2/ARE induction is fundamental to defense against reactive oxygen species (ROS) and serves as a key factor in the protection against toxic xenobiotics. 3-(3-Pyridylmethylidene)-2-Indolinone (PMID) is a derivative of 2-indolinone compounds which act as protein kinase inhibitors and show anti-tumor activity. However, the role of PMID in the oxidative stress remains unknown. In the present study, we showed that PMID induced the activation of ARE-mediated transcription, increased the DNA-binding activity of Nrf2 and then up-regulated the expression of antioxidant genes such as HO-1, SOD, and NQO1. The level of Nrf2 protein was increased in cells treated with PMID by a post-transcriptional mechanism. Under CHX treatment, the stability of Nrf2 protein was enhanced by PMID with decreased turnover rate. We showed that PMID reduced the ubiquitination of Nrf2 and disrupted the Cullin3 (Cul3)-Keap1 interaction. Furthermore, cells treated with PMID showed resistance to cytotoxicity by H(2)O(2) and pro-oxidant 6-OHDA. PMID also up-regulated the antioxidant level in BALB/c mice. Taken together, the compound PMID induces the ARE-mediated gene expression through stabilization of Nrf2 protein and activation of Nrf2/ARE pathway and protects against oxidative stress-mediated cell death.
Assuntos
Indóis/farmacologia , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo/fisiologia , Piridinas/farmacologia , Elementos de Resposta , Animais , Antioxidantes/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Glutationa/análise , Glutationa/metabolismo , Células Hep G2 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fator 2 Relacionado a NF-E2/genética , Superóxido Dismutase/metabolismo , Ativação Transcricional/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacosRESUMO
Human augmenter of liver regeneration (hALR) is a sulfhydryl oxidase that is highly expressed in spermatogonia and early spermatocytes. To investigate the physiological effects of hALR in spermatogenesis, we generated a hALR transgenic mouse model driven by the human TSPY (testis-specific protein, Y-encoded) promoter that allows the transgene to be specifically activated in the testes. hALR content was found to be increased in both germ cells. The histological and TUNEL analysis of transgenic testes revealed a number of spermatogenetic defects including primary spermatocyte overpopulation followed by depletion through apoptosis, degenerating and detached nucleated germ cells, haploid cell loss and intraepithelial vacuoles of varying sizes. In line with these features, adult transgenic male mice also displayed a reduction in fertility. Our data suggest that regulated spatial and temporal expression of hALR is required for normal testicular development and spermatogenesis, and overexpression of hALR results in influencing the sperm morphology and quantity and the eventual reduction in male fertility. Present findings in the mouse may be of interest to human male fertility.
Assuntos
Redutases do Citocromo/biossíntese , Infertilidade Masculina/genética , Espermatogênese/fisiologia , Animais , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Oligospermia , Oxirredutases atuantes sobre Doadores de Grupo Enxofre , Espermatogênese/genética , Testículo/metabolismoRESUMO
Hematopoietic stem and progenitor cells (HSPCs) possess the remarkable ability to regenerate the whole blood system in response to ablated stress demands. Delineating the mechanisms that maintain HSPCs during regenerative stresses is increasingly important. Here, it is shown that Hemgn is significantly induced by hematopoietic stresses including irradiation and bone marrow transplantation (BMT). Hemgn deficiency does not disturb steady-state hematopoiesis in young mice. Hemgn-/- HSPCs display defective engraftment activity during BMT with reduced homing and survival and increased apoptosis. Transcriptome profiling analysis reveals that upregulated genes in transplanted Hemgn-/- HSPCs are enriched for gene sets related to interferon gamma (IFN-γ) signaling. Hemgn-/- HSPCs show enhanced responses to IFN-γ treatment and increased aging over time. Blocking IFN-γ signaling in irradiated recipients either pharmacologically or genetically rescues Hemgn-/- HSPCs engraftment defect. Mechanistical studies reveal that Hemgn deficiency sustain nuclear Stat1 tyrosine phosphorylation via suppressing T-cell protein tyrosine phosphatase TC45 activity. Spermidine, a selective activator of TC45, rescues exacerbated phenotype of HSPCs in IFN-γ-treated Hemgn-/- mice. Collectively, these results identify that Hemgn is a critical regulator for successful engraftment and reconstitution of HSPCs in mice through negatively regulating IFN-γ signaling. Targeted Hemgn may be used to improve conditioning regimens and engraftment during HSPCs transplantation.
Assuntos
Transplante de Células-Tronco Hematopoéticas , Interferon gama , Animais , Hematopoese , Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/metabolismo , Interferon gama/metabolismo , Camundongos , Condicionamento Pré-TransplanteRESUMO
Hepassocin (HPS) is a specific mitogenic active factor for hepatocytes, and inhibits growth by overexpression in hepatocellular carcinoma (HCC) cells. However, the mechanism of HPS regulation on growth of liver-derived cells still remains largely unknown. In this study, we found that HPS was expressed and secreted into the extracellular medium in cultured L02 human hepatic cells; conditional medium of L02 cells promoted proliferation of L02 cells and this activity could be blocked by anti-HPS antibody. Moreover, we identified the presence of receptor for HPS on L02 cells and HepG2 human hepatoma cells. Overproduction of truncated HPS, which signal peptide was deleted, significantly inhibited the proliferation of HCC cells and induced cell cycle arrest. These findings suggest that HPS promotes hepatic cell line L02 cells proliferation via an autocrine mechanism and inhibits HCC cells proliferation by an intracrine pathway.
Assuntos
Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Proteínas de Neoplasias/metabolismo , Anticorpos Neutralizantes/farmacologia , Western Blotting , Ciclo Celular/genética , Ciclo Celular/fisiologia , Linhagem Celular Tumoral , Proliferação de Células , Ensaio de Imunoadsorção Enzimática , Fibrinogênio , Células Hep G2 , Hepatócitos/metabolismo , Humanos , Proteínas de Neoplasias/antagonistas & inibidores , Transdução de Sinais/genética , Transdução de Sinais/fisiologiaRESUMO
BACKGROUND: Human hepassocin (HPS) was originally detected by subtractive and differential cDNA cloning as a liver-specific gene that was markedly upregulated during liver regeneration. Previous studies suggested that HPS showed mitogenic activity on isolated hepatocytes in vitro. However, its in vivo functions remained largely unknown. Therefore, the function of recombinant human HPS during liver regeneration and chemically induced liver injury was investigated. METHODS: The proliferation of primary hepatocytes was examined by [(3)H]thymidine incorporation and immunohistological staining of proliferating cell nuclear antigen (PCNA). RNA interference was performed to knock down the endogenous expression of HPS. The proliferation of L02 cells was examined by MTS assay. The phosphorylation of ERK1/2 (extracellular signal-regulated kinase 1/2) was investigated by western blotting analysis. Assessment of liver injury (histology, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels) and of apoptosis, by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay, was performed. RESULTS: Purified recombinant human HPS showed specific mitogenic activity on primary hepatocytes and normal liver cell lines in a mitogen-activated protein kinase (MAPK)-dependent manner and stimulated the proliferation of hepatocytes in rats with 70% partial hepatectomy. Administration of HPS to rats after d-galactose and carbon tetrachloride (CCl(4)) treatment protected against liver injury (minimal liver necrosis, depressed ALT and AST levels, and decreased lethality), reduced apoptosis and enhanced proliferation. Knock-down of endogenous HPS in vivo enhanced the liver injury induced by d-galactose by increasing the apoptosis and elevating ALT and AST levels. CONCLUSIONS: HPS is a hepatic growth factor which can accelerate hepatocyte proliferation in vivo and protect against liver injury. These data point to the potential interest of HPS in the treatment of fulminant hepatic failure.
Assuntos
Hepatócitos/efeitos dos fármacos , Falência Hepática Aguda/tratamento farmacológico , Proteínas de Neoplasias/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/patologia , Modelos Animais de Doenças , Fibrinogênio , Hepatócitos/patologia , Humanos , Falência Hepática Aguda/patologia , Regeneração Hepática/efeitos dos fármacos , Masculino , Proteína Quinase 1 Ativada por Mitógeno/fisiologia , Proteína Quinase 3 Ativada por Mitógeno/fisiologia , Proteínas de Neoplasias/farmacologia , Interferência de RNA , Ratos , Ratos Wistar , Proteínas Recombinantes/farmacologia , Proteínas Recombinantes/uso terapêuticoRESUMO
The compound [3-(1H-benzimidazol-2-methylene)-5-(2-methylphenylaminosulfo)-2-indolone], known as Indo5, is a novel selective inhibitor of c-Met and Trks, and it is a promising anticancer candidate against hepatocellular carcinoma (HCC). Assessing the pharmacokinetic properties, tissue distribution, and toxicity of Indo5 is critical for its medicinal evaluation. A series of sensitive and specific liquid chromatography-tandem mass spectrometry methods were developed and validated to determine the concentration of Indo5 in rat plasma and tissue homogenates. These methods were then applied to investigate the pharmacokinetics and tissue distribution of Indo5 in rats. After intravenous injection of Indo5, the maximum concentration (Cmax) and the time at which Cmax was reached (Tmax) were 1,565.3 ± 286.2 ng/ml and 1 min, respectively. After oral administration, Cmax and Tmax were 54.7 ± 10.4 ng/ml and 2.0 ± 0.48 h, respectively. We calculated the absolute oral bioavailability of Indo5 in rats to be 1.59%. Following intravenous injection, the concentrations of Indo5 in various tissues showed the following order: liver > kidney ≈ heart > lung ≈ large intestine ≈ small intestine ≈ stomach > spleen > brain ≈ testes; hence, Indo5 distributed highest in the liver and could not cross the blood-brain or blood-testes barriers. Continuous injection of Indo5 for 21 days did not lead to liver injury, considering unchanged ALT and AST levels, normal histological architecture of the liver, and normal number and frequencies of immune cells in the liver, indicating a very low toxicity of Indo5 in vivo. Collectively, our findings provide a comprehensive understanding of the biological actions of Indo5 in vivo and further support its development as an antitumor treatment for HCC patients.
RESUMO
BACKGROUND: Toll-like receptor 5 (TLR5)-mediated pathways play critical roles in regulating the hepatic immune response and show hepatoprotective effects in mouse models of hepatic diseases. However, the role of TLR5 in experimental models of liver regeneration has not been reported. This study aimed to investigate the role of TLR5 in partial hepatectomy (PHx)-induced liver regeneration. METHODS: We performed 2/3 PHx in wild-type (WT) mice, TLR5 knockout mice, or TLR5 agonist CBLB502 treated mice, as a model of liver regeneration. Bacterial flagellin content was measured with ELISA, and hepatic TLR5 expression was determined with quantitative PCR analyses and flow cytometry. To study the effects of TLR5 on hepatocyte proliferation, we analyzed bromodeoxyuridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) expression with immunohistochemistry (IHC) staining. The effects of TLR5 during the priming phase of liver regeneration were examined with quantitative PCR analyses of immediate early gene mRNA levels, and with Western blotting analysis of hepatic NF-κB and STAT3 activation. Cytokine and growth factor production after PHx were detected with real-time PCR and cytometric bead array (CBA) assays. Oil Red O staining and hepatic lipid concentrations were analyzed to examine the effect of TLR5 on hepatic lipid accumulation after PHx. RESULTS: The bacterial flagellin content in the serum and liver increased, and the hepatic TLR5 expression was significantly up-regulated in WT mice after PHx. TLR5-deficient mice exhibited diminished numbers of BrdU- and PCNA-positive cells, suppressed immediate early gene expression, and decreased cytokine and growth factor production. Moreover, PHx-induced hepatic NF-κB and STAT3 activation was inhibited in Tlr5-/- mice, as compared with WT mice. Consistently, the administration of CBLB502 significantly promoted PHx-mediated hepatocyte proliferation, which was correlated with enhanced production of proinflammatory cytokines and the recruitment of macrophages and neutrophils in the liver. Furthermore, Tlr5-/- mice displayed significantly lower hepatic lipid concentrations and smaller Oil Red O positive areas than those in control mice after PHx. CONCLUSION: We reveal that TLR5 activation contributes to the initial events of liver regeneration after PHx. Our findings demonstrate that TLR5 signaling positively regulates liver regeneration and suggest the potential of TLR5 agonist to promote liver regeneration.
Assuntos
Regeneração Hepática/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Receptor 5 Toll-Like/uso terapêutico , Animais , Modelos Animais de Doenças , Regeneração Hepática/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Estatísticas não Paramétricas , Receptor 5 Toll-Like/metabolismoRESUMO
BRCA1/BRCA2-containing complex subunit 3 (BRCC3) is a lysine 63-specific deubiquitinase involved in multiple biological processes, such as DNA repair and immune responses. However, the regulation mechanism for BRCC3 protein stability is still unknown. Here, we demonstrate that BRCC3 is mainly degraded through the ubiquitin-proteasome pathway. The HECT-type E3 ubiquitin ligase WWP2 modulates BRCC3 ubiquitination and degradation. ABRO1, a subunit of the BRCC36 isopeptidase complex (BRISC), competes with WWP2 to bind to BRCC3, thereby preventing WWP2-mediated BRCC3 ubiquitination and enhancing BRCC3 stability. Functionally, we show that lentivirus-mediated overexpression of WWP2 in murine macrophages inhibits NLRP3 inflammasome activation by decreasing BRCC3 protein level. This study provides the first insights into the regulation of BRCC3 stability and expands our knowledge about the physiological function of WWP2.