RESUMO
BACKGROUND & AIMS: In vertebrates, canonical Hedgehog (Hh) pathway activation requires Smoothened (SMO) translocation to the primary cilium (Pc), followed by a GLI-mediated transcriptional response. In addition, a similar gene regulation occurs in response to growth factors/cytokines, although independently of SMO signalling. The Hh pathway plays a critical role in liver fibrosis/regeneration, however, the mechanism of activation in chronic liver injury is poorly understood. This study aimed to characterise Hh pathway activation upon thioacetamide (TAA)-induced chronic liver injury in vivo by defining Hh-responsive cells, namely cells harbouring Pc and Pc-localised SMO. METHODS: C57BL/6 mice (wild-type or Ptc1(+/-)) were TAA-treated. Liver injury and Hh ligand/pathway mRNA and protein expression were assessed in vivo. SMO/GLI manipulation and SMO-dependent/independent activation of GLI-mediated transcriptional response in Pc-positive (Pc(+)) cells were studied in vitro. RESULTS: In vivo, Hh activation was progressively induced following TAA. At the epithelial-mesenchymal interface, injured hepatocytes produced Hh ligands. Progenitors, myofibroblasts, leukocytes and hepatocytes were GLI2(+). Pc(+) cells increased following TAA, but only EpCAM(+)/GLI2(+) progenitors were Pc(+)/SMO(+). In vitro, SMO knockdown/hGli3-R overexpression reduced proliferation/viability in Pc(+) progenitors, whilst increased proliferation occurred with hGli1 overexpression. HGF induced GLI transcriptional activity independently of Pc/SMO. Ptc1(+/-) mice exhibited increased progenitor, myofibroblast and fibrosis responses. CONCLUSIONS: In chronic liver injury, Pc(+) progenitors receive Hh ligand signals and process it through Pc/SMO-dependent activation of GLI-mediated transcriptional response. Pc/SMO-independent GLI activation likely occurs in Pc(-)/GLI2(+) cells. Increased fibrosis in Hh gain-of-function mice likely occurs by primary progenitor expansion/proliferation and secondary fibrotic myofibroblast expansion, in close contact with progenitors.
Assuntos
Doença Hepática Induzida por Substâncias e Drogas/patologia , Cílios/fisiologia , Proteínas Hedgehog/fisiologia , Fígado/patologia , Transdução de Sinais/fisiologia , Animais , Doença Crônica , Transição Epitelial-Mesenquimal , Fatores de Transcrição Kruppel-Like/análise , Fatores de Transcrição Kruppel-Like/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Nucleares/análise , Receptores Acoplados a Proteínas G/fisiologia , Receptor Smoothened , Tioacetamida , Proteína GLI1 em Dedos de Zinco , Proteína Gli2 com Dedos de ZincoRESUMO
Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that binds and is activated by collagens. Transcriptional profiling of cirrhosis in human liver using a DNA array and quantitative PCR detected elevated mRNA expression of DDR1 compared with that in nondiseased liver. The present study characterized DDR1 expression in cirrhotic and nondiseased human liver and examined the cellular effects of DDR1 expression. mRNA expression of all five isoforms of DDR1 was detected in human liver, whereas DDR1a demonstrated differential expression in liver with hepatitis C virus and primary biliary cirrhosis compared with nondiseased liver. In addition, immunoblot analysis detected shed fragments of DDR1 more readily in cirrhotic liver than in nondiseased liver. Inasmuch as DDR1 is subject to protease-mediated cleavage after prolonged interaction with collagen, this differential expression may indicate more intense activation of DDR1 protein in cirrhotic compared with nondiseased liver. In situ hybridization and immunofluorescence localized intense DDR1 mRNA and protein expression to epithelial cells including hepatocytes at the portal-parenchymal interface and the luminal aspect of the biliary epithelium. Overexpression of DDR1a altered hepatocyte behavior including increased adhesion and less migration on extracelular matrix substrates. DDR1a regulated extracellular expression of matrix metalloproteinases 1 and 2. These data elucidate DDR1 function pertinent to cirrhosis and indicate the importance of epithelial cell-collagen interactions in chronic liver injury.
Assuntos
Cirrose Hepática/enzimologia , Cirrose Hepática/patologia , Fígado/enzimologia , Fígado/patologia , Receptores Proteína Tirosina Quinases/metabolismo , Adolescente , Adulto , Adesão Celular , Linhagem Celular , Movimento Celular , Receptor com Domínio Discoidina 1 , Feminino , Regulação da Expressão Gênica , Proteínas de Fluorescência Verde/metabolismo , Humanos , Imuno-Histoquímica , Masculino , Metaloproteinases da Matriz/metabolismo , Pessoa de Meia-Idade , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores Proteína Tirosina Quinases/química , Receptores Proteína Tirosina Quinases/genética , Proteínas Recombinantes de Fusão/metabolismo , Transfecção , Adulto JovemRESUMO
N-terminal truncation of chemokines by proteases including dipeptidyl peptidase (DP) IV significantly alters their biological activity; generally ablating cognate G-protein coupled receptor engagement and often generating potent receptor antagonists. DP8 is a recently recognised member of the prolyl oligopeptidase gene family that includes DPIV. Since DPIV is known to process chemokines we surveyed 27 chemokines for cleavage by DP8. We report DP8 cleavage of the N-terminal two residues of IP10 (CXCL10), ITAC (CXCL11) and SDF-1 (CXCL12). This has implications for DP8 substrate specificity. Chemokine cleavage and inactivation may occur in vivo upon cell lysis and release of DP8 or in the inactivation of internalized chemokine/receptor complexes.
Assuntos
Quimiocina CXCL10/metabolismo , Quimiocina CXCL11/metabolismo , Quimiocina CXCL12/metabolismo , Dipeptidases/metabolismo , Quimiocina CXCL10/química , Quimiocina CXCL11/química , Quimiocina CXCL12/química , Dipeptidases/isolamento & purificação , Dipeptidil Peptidase 4/isolamento & purificação , Dipeptidil Peptidase 4/metabolismo , Meia-Vida , Humanos , Cinética , Peso Molecular , Processamento de Proteína Pós-Traducional , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Solubilidade , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Especificidade por SubstratoRESUMO
DPL2 (DPP10) found at chromosome 2q14.1 is a member of the dipeptidyl peptidase IV (DPIV) gene family. Here we characterize a novel short DPL2 isoform (DPL2-s), a 789-amino acid protein, that differs from the previously described long DPL2 isoform (DPL2-l) at the N-terminal cytoplasmic domain by 13 amino acids. The two DPL2 isoforms use alternate first exons. DPL2 mRNA was expressed mainly in the brain and pancreas. Multiple forms of recombinant DPL2-s protein were observed in 293T cells, having mobilities 96 kDa, 100 kDa, and approximately 250 kDa which may represent soluble DPL2, transmembrane DPL2 and multimeric DPL2 respectively. DPL2 is glycosylated as a band shift is observed following PNGase F deglycosylation. DPL2-s was expressed primarily on the cell surface of transfected 293T and PC12 cells. DPL2-s exhibits high sequence homology with other DPIV peptidases, but lacks a catalytic serine residue and lacks dipeptidyl peptidase activity. Substitutions of Gly(644)-->Ser, Lys(643)Gly(644)-->TrpSer, or Asp(561)Lys(643)Gly(644)-->TyrTrpSer in the catalytic motif did not confer dipeptidyl peptidase activity upon DPL2-s. Thus, although DPL2 is similar in structure and sequence to the other dipeptidyl peptidases, it lacks vital residues required to confer dipeptidyl peptidase activity and has instead evolved features that enable it to act as an important component of voltage-gated potassium channels.
Assuntos
Encéfalo/enzimologia , Dipeptidil Peptidases e Tripeptidil Peptidases/química , Dipeptidil Peptidases e Tripeptidil Peptidases/genética , Processamento Alternativo , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Membrana Celular/enzimologia , Clonagem Molecular , Citoplasma/enzimologia , DNA Complementar/genética , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Expressão Gênica , Glicosilação , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Pâncreas/enzimologia , Canais de Potássio de Abertura Dependente da Tensão da Membrana/química , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , TransfecçãoRESUMO
Dipeptidyl peptidase (DP) IV has a distinct substrate specificity in hydrolyzing a post-proline bond. Here we present novel data on the sizes and tissue distribution of human and rat gene products and the peptidase activity of the DPIV-related gene DP9. A short cDNA of 2589 bp and a long cDNA of 3006 bp of DP9 were cloned. A ubiquitous predominant DP9 mRNA transcript at 4.4 kb represented the short form, whereas a less abundant 5.0-kb transcript present predominantly in muscle represented the long form. Both forms of DP9 have no transmembrane domain and two potential N-linked glycosylation sites. DP9 exhibited post-proline dipeptidyl aminopeptidase activity and was a cytoplasmic, 110-kDa monomer. Thus, the six DPIV gene family members have diverse characteristics: only DP9 and DP8 have exclusively cytoplasmic localization and only DP9, DP8, fibroblast activation protein (FAP) and DPIV have peptidase activity.
Assuntos
Adenosina Desaminase/metabolismo , Citoplasma/metabolismo , Dipeptidil Peptidase 4 , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Glicoproteínas/metabolismo , Processamento Alternativo , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Clonagem Molecular , Primers do DNA , Dipeptidil Peptidases e Tripeptidil Peptidases/química , Dipeptidil Peptidases e Tripeptidil Peptidases/genética , Humanos , Dados de Sequência Molecular , Ratos , Homologia de Sequência de AminoácidosRESUMO
We have identified three novel members of the DPIV gene family using database mining approaches. Recombinant DP8 shares a post-proline dipeptidyl aminopeptidase activity with the closely related enzymes DPIV and FAP. The similarities between DP8, DP9 and DPIV in tissue expression pattern suggest a potential role for DP8 and DP9 in liver disease, T cell activation and immune function. The role of the two novel enzymes DP8 and DP9 and the other non-enzyme member DPL2 in human disease will be the focus of further studies.
Assuntos
Dipeptidil Peptidase 4/genética , Família Multigênica/genética , Dipeptidil Peptidase 4/metabolismo , Evolução Molecular , Humanos , Íntrons , CinéticaRESUMO
AIM: To investigate the expression of dipeptidyl peptidase (DPP) 8 and DPP9 in lymphocytes and various models of liver fibrosis. METHODS: DPP8 and DPP9 expression were measured in mouse splenic CD4⺠T-cells, CD8⺠T-cells and B-cells (B220âº), human lymphoma cell lines and mouse splenocytes stimulated with pokeweed mitogen (PWM) or lipopolysaccharide (LPS), and in dithiothreitol (DTT) and mitomycin-C treated Raji cells. DPP8 and DPP9 expression were measured in epidermal growth factor (EGF) treated Huh7 hepatoma cells, in fibrotic liver samples from mice treated with carbon tetrachloride (CCl4) and from multidrug resistance gene 2 (Mdr2/Abcb4) gene knockout (gko) mice with biliary fibrosis, and in human end stage primary biliary cirrhosis (PBC). RESULTS: All three lymphocyte subsets expressed DPP8 and DPP9 mRNA. DPP8 and DPP9 expression were upregulated in both PWM and LPS stimulated mouse splenocytes and in both Jurkat T- and Raji B-cell lines. DPP8 and DPP9 were downregulated in DTT treated and upregulated in mitomycin-C treated Raji cells. DPP9-transfected Raji cells exhibited more annexin V⺠cells and associated apoptosis. DPP8 and DPP9 mRNA were upregulated in CCl4 induced fibrotic livers but not in the lymphocytes isolated from such livers, while DPP9 was upregulated in EGF stimulated Huh7 cells. In contrast, intrahepatic DPP8 and DPP9 mRNA expression levels were low in the Mdr2 gko mouse and in human PBC compared to non-diseased livers. CONCLUSION: These expression patterns point to biological roles for DPP8 and DPP9 in lymphocyte activation and apoptosis and in hepatocytes during liver disease pathogenesis.
Assuntos
Doença Hepática Induzida por Substâncias e Drogas/enzimologia , Dipeptidases/metabolismo , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Cirrose Hepática Biliar/enzimologia , Cirrose Hepática Experimental/enzimologia , Fígado/enzimologia , Ativação Linfocitária , Subpopulações de Linfócitos/enzimologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/deficiência , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Adulto , Idoso , Animais , Apoptose , Tetracloreto de Carbono , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/genética , Doença Hepática Induzida por Substâncias e Drogas/imunologia , Doença Hepática Induzida por Substâncias e Drogas/patologia , Dipeptidases/genética , Dipeptidil Peptidase 4/deficiência , Dipeptidil Peptidase 4/genética , Dipeptidil Peptidases e Tripeptidil Peptidases/genética , Endopeptidases , Feminino , Gelatinases/deficiência , Gelatinases/genética , Humanos , Células Jurkat , Fígado/inervação , Fígado/patologia , Cirrose Hepática Biliar/etiologia , Cirrose Hepática Biliar/genética , Cirrose Hepática Biliar/imunologia , Cirrose Hepática Biliar/patologia , Cirrose Hepática Experimental/etiologia , Cirrose Hepática Experimental/genética , Cirrose Hepática Experimental/imunologia , Cirrose Hepática Experimental/patologia , Subpopulações de Linfócitos/imunologia , Masculino , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , RNA Mensageiro/metabolismo , Serina Endopeptidases/deficiência , Serina Endopeptidases/genética , Fatores de Tempo , Membro 4 da Subfamília B de Transportadores de Cassetes de Ligação de ATPAssuntos
Dipeptidases/metabolismo , Dipeptidil Peptidase 4/metabolismo , Serina Endopeptidases/metabolismo , Animais , Linhagem Celular , Dipeptidases/química , Dipeptidases/genética , Dipeptidil Peptidase 4/química , Dipeptidil Peptidase 4/genética , Concentração de Íons de Hidrogênio , Peptídeo Hidrolases/metabolismo , Prolil Oligopeptidases , Serina Endopeptidases/química , Serina Endopeptidases/genética , Inibidores de Serina Proteinase/metabolismo , Especificidade por SubstratoAssuntos
Dipeptidil Peptidase 4/química , Dipeptidil Peptidase 4/metabolismo , Animais , Antígenos de Neoplasias/química , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Sítios de Ligação , Biomarcadores Tumorais/química , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Dipeptidases/química , Dipeptidases/genética , Dipeptidases/metabolismo , Dipeptidil Peptidase 4/genética , Dipeptidil Peptidases e Tripeptidil Peptidases/química , Dipeptidil Peptidases e Tripeptidil Peptidases/genética , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Endopeptidases , Matriz Extracelular/metabolismo , Gelatinases , Humanos , Proteínas de Membrana , Modelos Moleculares , Dados de Sequência Molecular , Família Multigênica , Neoplasias/enzimologia , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Peptídeo Hidrolases/química , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Canais de Potássio/química , Canais de Potássio/genética , Canais de Potássio/metabolismo , Conformação Proteica , Serina Endopeptidases/química , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismoAssuntos
Apoptose/fisiologia , Adesão Celular/fisiologia , Movimento Celular/fisiologia , Dipeptidases/metabolismo , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Motivos de Aminoácidos , Linhagem Celular , Citoesqueleto/metabolismo , Dipeptidases/genética , Dipeptidil Peptidases e Tripeptidil Peptidases/genética , Humanos , Família Multigênica , Fenótipo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoAssuntos
Família Multigênica , Serina Endopeptidases/genética , Sequência de Bases , Primers do DNA , Dipeptidil Peptidase 4/genética , Dipeptidil Peptidase 4/metabolismo , Humanos , Prolil Oligopeptidases , Proteínas Recombinantes de Fusão/metabolismo , Deleção de Sequência , Serina Endopeptidases/metabolismoRESUMO
The dipeptidyl peptidase IV (DPIV) enzyme family contains both potential and proven therapeutic targets. Recent reports indicate the presence of DP8 and DP9 in peripheral blood lymphocytes, testis, lung, and brain. For a more comprehensive understanding of DP8 and DP9 tissue and cellular expression, mRNA and enzyme activity were examined. Many organs from C57BL/6 wild-type and DPIV gene-knockout mice were examined; DP8/9 enzyme activity was detected in the immune system, brain, testis, muscle, and epithelia. In situ hybridization localized DP8 and DP9 mRNA to lymphocytes and epithelial cells in liver, gastrointestinal tract, lymph node, spleen, and lung. DP8 and DP9 mRNA was detected in baboon and mouse testis, and DP9 expression was elevated in human testicular cancers. DP8 and DP9 mRNA were ubiquitous in day 17 mouse embryo, with greatest expression in epithelium (skin and gastrointestinal tract) and brain. Thus, DP8 and DP9 are widely expressed enzymes. Their expression in lymphocytes and epithelia indicates potential for roles in the digestive and immune systems. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
Assuntos
Dipeptidil Peptidase 4/genética , Dipeptidil Peptidase 4/metabolismo , Regulação Enzimológica da Expressão Gênica , Adolescente , Animais , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/metabolismo , Criança , Dipeptidil Peptidase 4/deficiência , Inibidores da Dipeptidil Peptidase IV , Sistema Endócrino/efeitos dos fármacos , Sistema Endócrino/metabolismo , Epitélio/efeitos dos fármacos , Epitélio/metabolismo , Etilmaleimida/farmacologia , Técnicas de Inativação de Genes , Humanos , Sistema Imunitário/efeitos dos fármacos , Sistema Imunitário/metabolismo , Hibridização In Situ , Masculino , Camundongos , Músculos/efeitos dos fármacos , Músculos/metabolismo , Papio , Inibidores de Proteases/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reprodução , Testículo/efeitos dos fármacos , Testículo/metabolismoRESUMO
Dipeptidyl peptidase IV (DP-IV/CD26), fibroblast activation protein (FAP), DP-like 1 (DPL1), DP8, DP9, and DPL2 comprise the CD26 gene family. CD26/DP-IV has roles in liver disease, T cell costimulation, chemokine biology, type II diabetes, and tumor biology. DPIV substrates include the glucagonlike peptides, neuropeptide Y, and the chemokines CCL3, CCL5, CCL11, CCL22, and CXCL12. We have proposed that the extracellular region of CD26 is analogous to prolyl oligopeptidase in consisting of an alpha/beta hydrolase domain contributed by both N- and C-terminal portions of the polypeptide and a seven-blade beta-propeller domain. Replacing the C-terminal portion of the predicted alpha/beta hydrolase domain of CD26 (residues 501-766) with the homologous portion of DP8 or DP9 produced intact proteins. However, these chimeric proteins lacked dimerization and peptidase activity, suggesting that CD26 dimerization requires the C-terminal portion of the alpha/beta hydrolase domain. Deleting some N-terminal residues of the alpha/beta hydrolase domain of CD26 ablated peptidase activity and greatly diminished cell surface expression. Together with previous data that CD26 peptidase activity requires the C-terminal 20 residues, this suggests that peptidase activity requires the entire alpha/beta hydrolase domain. The catalytic triad of DP8 was shown to be Ser(739)-Asp (817)-His(849). Glu(259) of DP8, a residue distant from the catalytic triad yet greatly conserved in the CD26 gene family, was shown to be required for peptidase activity. These data concord with our predicted CD26 structure, indicate that biosynthesis of a functional fragment of CD26 is difficult, and confirm the functional homology of DP8 with CD26.