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1.
J Hepatol ; 60(1): 143-51, 2014 Jan.
Article in English | MEDLINE | ID: mdl-23978713

ABSTRACT

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.


Subject(s)
Chemical and Drug Induced Liver Injury/pathology , Cilia/physiology , Hedgehog Proteins/physiology , Liver/pathology , Signal Transduction/physiology , Animals , Chronic Disease , Epithelial-Mesenchymal Transition , Kruppel-Like Transcription Factors/analysis , Kruppel-Like Transcription Factors/physiology , Male , Mice , Mice, Inbred C57BL , Nuclear Proteins/analysis , Receptors, G-Protein-Coupled/physiology , Smoothened Receptor , Thioacetamide , Zinc Finger Protein GLI1 , Zinc Finger Protein Gli2
2.
World J Gastroenterol ; 19(19): 2883-93, 2013 May 21.
Article in English | MEDLINE | ID: mdl-23704821

ABSTRACT

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⁺ T-cells, CD8⁺ T-cells and B-cells (B220⁺), 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⁺ 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.


Subject(s)
Chemical and Drug Induced Liver Injury/enzymology , Dipeptidases/metabolism , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Liver Cirrhosis, Biliary/enzymology , Liver Cirrhosis, Experimental/enzymology , Liver/enzymology , Lymphocyte Activation , Lymphocyte Subsets/enzymology , ATP Binding Cassette Transporter, Subfamily B/deficiency , ATP Binding Cassette Transporter, Subfamily B/genetics , Adult , Aged , Animals , Apoptosis , Carbon Tetrachloride , Chemical and Drug Induced Liver Injury/etiology , Chemical and Drug Induced Liver Injury/genetics , Chemical and Drug Induced Liver Injury/immunology , Chemical and Drug Induced Liver Injury/pathology , Dipeptidases/genetics , Dipeptidyl Peptidase 4/deficiency , Dipeptidyl Peptidase 4/genetics , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/genetics , Endopeptidases , Female , Gelatinases/deficiency , Gelatinases/genetics , Humans , Jurkat Cells , Liver/innervation , Liver/pathology , Liver Cirrhosis, Biliary/etiology , Liver Cirrhosis, Biliary/genetics , Liver Cirrhosis, Biliary/immunology , Liver Cirrhosis, Biliary/pathology , Liver Cirrhosis, Experimental/etiology , Liver Cirrhosis, Experimental/genetics , Liver Cirrhosis, Experimental/immunology , Liver Cirrhosis, Experimental/pathology , Lymphocyte Subsets/immunology , Male , Membrane Proteins/deficiency , Membrane Proteins/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Middle Aged , RNA, Messenger/metabolism , Serine Endopeptidases/deficiency , Serine Endopeptidases/genetics , Time Factors , ATP-Binding Cassette Sub-Family B Member 4
3.
Am J Pathol ; 178(3): 1134-44, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21356365

ABSTRACT

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.


Subject(s)
Liver Cirrhosis/enzymology , Liver Cirrhosis/pathology , Liver/enzymology , Liver/pathology , Receptor Protein-Tyrosine Kinases/metabolism , Adolescent , Adult , Cell Adhesion , Cell Line , Cell Movement , Discoidin Domain Receptor 1 , Female , Gene Expression Regulation , Green Fluorescent Proteins/metabolism , Humans , Immunohistochemistry , Male , Matrix Metalloproteinases/metabolism , Middle Aged , Protein Isoforms/chemistry , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptor Protein-Tyrosine Kinases/chemistry , Receptor Protein-Tyrosine Kinases/genetics , Recombinant Fusion Proteins/metabolism , Transfection , Young Adult
4.
J Histochem Cytochem ; 57(11): 1025-40, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19581630

ABSTRACT

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.


Subject(s)
Dipeptidyl Peptidase 4/genetics , Dipeptidyl Peptidase 4/metabolism , Gene Expression Regulation, Enzymologic , Adolescent , Animals , Central Nervous System/drug effects , Central Nervous System/metabolism , Child , Dipeptidyl Peptidase 4/deficiency , Dipeptidyl-Peptidase IV Inhibitors , Endocrine System/drug effects , Endocrine System/metabolism , Epithelium/drug effects , Epithelium/metabolism , Ethylmaleimide/pharmacology , Gene Knockout Techniques , Humans , Immune System/drug effects , Immune System/metabolism , In Situ Hybridization , Male , Mice , Muscles/drug effects , Muscles/metabolism , Papio , Protease Inhibitors/pharmacology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reproduction , Testis/drug effects , Testis/metabolism
5.
FEBS Lett ; 582(5): 819-25, 2008 Mar 05.
Article in English | MEDLINE | ID: mdl-18275857

ABSTRACT

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.


Subject(s)
Chemokine CXCL10/metabolism , Chemokine CXCL11/metabolism , Chemokine CXCL12/metabolism , Dipeptidases/metabolism , Chemokine CXCL10/chemistry , Chemokine CXCL11/chemistry , Chemokine CXCL12/chemistry , Dipeptidases/isolation & purification , Dipeptidyl Peptidase 4/isolation & purification , Dipeptidyl Peptidase 4/metabolism , Half-Life , Humans , Kinetics , Molecular Weight , Protein Processing, Post-Translational , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Solubility , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Substrate Specificity
9.
Biochim Biophys Acta ; 1764(1): 33-43, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16290253

ABSTRACT

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.


Subject(s)
Brain/enzymology , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/chemistry , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/genetics , Alternative Splicing , Amino Acid Sequence , Amino Acid Substitution , Animals , Base Sequence , Cell Line , Cell Membrane/enzymology , Cloning, Molecular , Cytoplasm/enzymology , DNA, Complementary/genetics , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Gene Expression , Glycosylation , Humans , Isoenzymes/chemistry , Isoenzymes/genetics , Isoenzymes/metabolism , Molecular Sequence Data , Mutagenesis, Site-Directed , Pancreas/enzymology , Potassium Channels, Voltage-Gated/chemistry , Potassium Channels, Voltage-Gated/genetics , Potassium Channels, Voltage-Gated/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid , Transfection
10.
Biochim Biophys Acta ; 1679(1): 18-28, 2004 Jul 13.
Article in English | MEDLINE | ID: mdl-15245913

ABSTRACT

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.


Subject(s)
Adenosine Deaminase/metabolism , Cytoplasm/metabolism , Dipeptidyl Peptidase 4 , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Glycoproteins/metabolism , Alternative Splicing , Amino Acid Sequence , Animals , Base Sequence , Cell Line , Cloning, Molecular , DNA Primers , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/chemistry , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/genetics , Humans , Molecular Sequence Data , Rats , Sequence Homology, Amino Acid
12.
Adv Exp Med Biol ; 524: 79-86, 2003.
Article in English | MEDLINE | ID: mdl-12675227

ABSTRACT

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.


Subject(s)
Dipeptidyl Peptidase 4/genetics , Multigene Family/genetics , Dipeptidyl Peptidase 4/metabolism , Evolution, Molecular , Humans , Introns , Kinetics
13.
Biochemistry ; 42(3): 694-701, 2003 Jan 28.
Article in English | MEDLINE | ID: mdl-12534281

ABSTRACT

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.


Subject(s)
Dipeptidyl Peptidase 4/chemistry , Dipeptidyl Peptidase 4/genetics , Gene Expression Regulation , Multigene Family , Animals , COS Cells , Catalysis , Catalytic Domain/genetics , Cell Line , Conserved Sequence , Dimerization , Dipeptidyl Peptidase 4/biosynthesis , Gene Expression Regulation/genetics , Humans , Hydrolases/chemistry , Multigene Family/genetics , Mutagenesis, Site-Directed , Point Mutation , Prolyl Oligopeptidases , Rats , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Sequence Deletion/genetics , Sequence Homology, Amino Acid , Serine Endopeptidases/chemistry , Structure-Activity Relationship , Transfection
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