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McBroome J, Liang D, Corbett-Detig R. Fine-Scale Position Effects Shape the Distribution of Inversion Breakpoints in Drosophila melanogaster. Genome Biol Evol 2021; 12:1378-1391. [PMID: 32437518 PMCID: PMC7487137 DOI: 10.1093/gbe/evaa103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2020] [Indexed: 12/20/2022] Open
Abstract
Chromosomal inversions are among the primary drivers of genome structure evolution in a wide range of natural populations. Although there is an impressive array of theory and empirical analyses that have identified conditions under which inversions can be positively selected, comparatively little data are available on the fitness impacts of these genome structural rearrangements themselves. Because inversion breakpoints can disrupt functional elements and alter chromatin domains, the precise positioning of an inversion’s breakpoints can strongly affect its fitness. Here, we compared the fine-scale distribution of low-frequency inversion breakpoints with those of high-frequency inversions and inversions that have gone to fixation between Drosophila species. We identified a number of differences among frequency classes that may influence inversion fitness. In particular, breakpoints that are proximal to insulator elements, generate large tandem duplications, and minimize impacts on gene coding spans which are more prevalent in high-frequency and fixed inversions than in rare inversions. The data suggest that natural selection acts to preserve both genes and larger cis-regulatory networks in the occurrence and spread of rearrangements. These factors may act to limit the availability of high-fitness arrangements when suppressed recombination is favorable.
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Affiliation(s)
- Jakob McBroome
- Department of Biomolecular Engineering, University of California Santa Cruz
| | - David Liang
- Department of Biomolecular Engineering, University of California Santa Cruz
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2
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Saenko SV, Chouteau M, Piron-Prunier F, Blugeon C, Joron M, Llaurens V. Unravelling the genes forming the wing pattern supergene in the polymorphic butterfly Heliconius numata. EvoDevo 2019; 10:16. [PMID: 31406559 PMCID: PMC6686539 DOI: 10.1186/s13227-019-0129-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 07/12/2019] [Indexed: 11/25/2022] Open
Abstract
Background Unravelling the genetic basis of polymorphic characters is central to our understanding of the origins and diversification of living organisms. Recently, supergenes have been implicated in a wide range of complex polymorphisms, from adaptive colouration in butterflies and fish to reproductive strategies in birds and plants. The concept of a supergene is now a hot topic in biology, and identification of its functional elements is needed to shed light on the evolution of highly divergent adaptive traits. Here, we apply different gene expression analyses to study the supergene P that controls polymorphism of mimetic wing colour patterns in the neotropical butterfly Heliconius numata. Results We performed de novo transcriptome assembly and differential expression analyses using high-throughput Illumina RNA sequencing on developing wing discs of different H. numata morphs. Within the P interval, 30 and 17 of the 191 transcripts were expressed differentially in prepupae and day-1 pupae, respectively. Among these is the gene cortex, known to play a role in wing pattern formation in Heliconius and other Lepidoptera. Our in situ hybridization experiments confirmed the relationship between cortex expression and adult wing patterns. Conclusions This study found the majority of genes in the P interval to be expressed in the developing wing discs during the critical stages of colour pattern formation, and detect drastic changes in expression patterns in multiple genes associated with structural variants. The patterns of expression of cortex only partially recapitulate the variation in adult phenotype, suggesting that the remaining phenotypic variation could be controlled by other genes within the P interval. Although functional studies on cortex are now needed to determine its exact developmental role, our results are in accordance with the classical supergene hypothesis, whereby several genes inherited together due to tight linkage control a major developmental switch. Electronic supplementary material The online version of this article (10.1186/s13227-019-0129-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Suzanne V Saenko
- 1Institut de Systématique, Evolution et Biodiversité, UMR 7205 (CNRS, MNHN, Sorbonne Université, EPHE), Muséum National d'Histoire Naturelle CP50, 57 rue Cuvier, 75005 Paris, France
| | - Mathieu Chouteau
- 2Laboratoire Ecologie, Evolution, Interactions Des Systèmes Amazoniens (LEEISA), USR 3456, CNRS Guyane, Université De Guyane, 275 route de Montabo, 97334 Cayenne, French Guiana
| | - Florence Piron-Prunier
- 1Institut de Systématique, Evolution et Biodiversité, UMR 7205 (CNRS, MNHN, Sorbonne Université, EPHE), Muséum National d'Histoire Naturelle CP50, 57 rue Cuvier, 75005 Paris, France
| | - Corinne Blugeon
- Genomic Facility, Institut de Biologie de l'Ecole normale superieure (IBENS), École normale supérieure, CNRS, INSERM, PSL Université Paris, 75005 Paris, France
| | - Mathieu Joron
- 4Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier, École Pratique des Hautes Études, Université Paul Valéry, 34293 Montpellier 5, France
| | - Violaine Llaurens
- 1Institut de Systématique, Evolution et Biodiversité, UMR 7205 (CNRS, MNHN, Sorbonne Université, EPHE), Muséum National d'Histoire Naturelle CP50, 57 rue Cuvier, 75005 Paris, France
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3
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Shiina Y, Muto T, Zhang Z, Baihaqie A, Yoshizawa T, Lee HIJ, Park E, Tsukiji S, Takimoto K. Fly DPP10 acts as a channel ancillary subunit and possesses peptidase activity. Sci Rep 2016; 6:26290. [PMID: 27198182 PMCID: PMC4873792 DOI: 10.1038/srep26290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/28/2016] [Indexed: 01/04/2023] Open
Abstract
Mammalian DPP6 (DPPX) and DPP10 (DPPY) belong to a family of dipeptidyl peptidases, but lack enzyme activity. Instead, these proteins form complexes with voltage-gated K(+) channels in Kv4 family to control their gating and other properties. Here, we find that the fly DPP10 ortholog acts as an ancillary subunit of Kv4 channels and digests peptides. Similarly to mammalian DPP10, the fly ortholog tightly binds to rat Kv4.3 protein. The association causes negative shifts in voltage dependence of channel activation and steady state inactivation. It also results in faster inactivation and recovery from inactivation. In addition to its channel regulatory role, fly DPP10 exhibits significant dipeptidyl peptidase activity with Gly-Pro-MCA (glycyl-L-proline 4-methylcoumaryl-7-amide) as a substrate. Heterologously expressed Flag-tagged fly DPP10 and human DPP4 show similar Km values towards this substrate. However, fly DPP10 exhibits approximately a 6-times-lower relative kcat value normalized with anti-Flag immunoreactivity than human DPP4. These results demonstrate that fly DPP10 is a dual functional protein, controlling Kv4 channel gating and removing bioactive peptides.
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Affiliation(s)
- Yohei Shiina
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Tomohiro Muto
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Zhili Zhang
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Ahmad Baihaqie
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Takamasa Yoshizawa
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Hye-In J Lee
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Eulsoon Park
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
| | - Shinya Tsukiji
- Frontier Research Institute for Materials Science, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-855, Japan.,Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-855, Japan
| | - Koichi Takimoto
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
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4
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Wagner L, Klemann C, Stephan M, von Hörsten S. Unravelling the immunological roles of dipeptidyl peptidase 4 (DPP4) activity and/or structure homologue (DASH) proteins. Clin Exp Immunol 2016; 184:265-83. [PMID: 26671446 DOI: 10.1111/cei.12757] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/01/2015] [Accepted: 12/14/2015] [Indexed: 12/31/2022] Open
Abstract
Dipeptidyl peptidase (DPP) 4 (CD26, DPP4) is a multi-functional protein involved in T cell activation by co-stimulation via its association with adenosine deaminase (ADA), caveolin-1, CARMA-1, CD45, mannose-6-phosphate/insulin growth factor-II receptor (M6P/IGFII-R) and C-X-C motif receptor 4 (CXC-R4). The proline-specific dipeptidyl peptidase also modulates the bioactivity of several chemokines. However, a number of enzymes displaying either DPP4-like activities or representing structural homologues have been discovered in the past two decades and are referred to as DPP4 activity and/or structure homologue (DASH) proteins. Apart from DPP4, DASH proteins include fibroblast activation protein alpha (FAP), DPP8, DPP9, DPP4-like protein 1 (DPL1, DPP6, DPPX L, DPPX S), DPP4-like protein 2 (DPL2, DPP10) from the DPP4-gene family S9b and structurally unrelated enzyme DPP2, displaying DPP4-like activity. In contrast, DPP6 and DPP10 lack enzymatic DPP4-like activity. These DASH proteins play important roles in the immune system involving quiescence (DPP2), proliferation (DPP8/DPP9), antigen-presenting (DPP9), co-stimulation (DPP4), T cell activation (DPP4), signal transduction (DPP4, DPP8 and DPP9), differentiation (DPP4, DPP8) and tissue remodelling (DPP4, FAP). Thus, they are involved in many pathophysiological processes and have therefore been proposed for potential biomarkers or even drug targets in various cancers (DPP4 and FAP) and inflammatory diseases (DPP4, DPP8/DPP9). However, they also pose the challenge of drug selectivity concerning other DASH members for better efficacy and/or avoidance of unwanted side effects. Therefore, this review unravels the complex roles of DASH proteins in immunology.
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Affiliation(s)
- L Wagner
- Deutschsprachige Selbsthilfegruppe für Alkaptonurie (DSAKU) e.V, Stuttgart.,Department for Experimental Therapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - C Klemann
- Centre of Paediatric Surgery.,Centre for Paediatrics and Adolescent Medicine
| | - M Stephan
- Clinic for Psychosomatics and Psychotherapy, Hannover Medical School, Hannover
| | - S von Hörsten
- Department for Experimental Therapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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5
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A high resolution map of mammalian X chromosome fragile regions assessed by large-scale comparative genomics. Mamm Genome 2014; 25:618-35. [PMID: 25086724 DOI: 10.1007/s00335-014-9537-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/14/2014] [Indexed: 10/24/2022]
Abstract
Chromosomal evolution involves multiple changes at structural and numerical levels. These changes, which are related to the variation of the gene number and their location, can be tracked by the identification of syntenic blocks (SB). First reports proposed that ~180-280 SB might be shared by mouse and human species. More recently, further studies including additional genomes have identified up to ~1,400 SB during the evolution of eutherian species. A considerable number of studies regarding the X chromosome's structure and evolution have been undertaken because of its extraordinary biological impact on reproductive fitness and speciation. Some have identified evolutionary breakpoint regions and fragile sites at specific locations in the human X chromosome. However, mapping these regions to date has involved using low-to-moderate resolution techniques. Such scenario might be related to underestimating their total number and giving an inaccurate location. The present study included using a combination of bioinformatics methods for identifying, at base-pair level, chromosomal rearrangements occurring during X chromosome evolution in 13 mammalian species. A comparative technique using four different algorithms was used for optimizing the detection of hotspot regions in the human X chromosome. We identified a significant interspecific variation in SB size which was related to genetic information gain regarding the human X chromosome. We found that human hotspot regions were enriched by LINE-1 and Alu transposable elements, which may have led to intraspecific chromosome rearrangement events. New fragile regions located in the human X chromosome have also been postulated. We estimate that the high resolution map of X chromosome fragile sites presented here constitutes useful data concerning future studies on mammalian evolution and human disease.
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6
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Mercer RCC, Ma L, Watts JC, Strome R, Wohlgemuth S, Yang J, Cashman NR, Coulthart MB, Schmitt-Ulms G, Jhamandas JH, Westaway D. The prion protein modulates A-type K+ currents mediated by Kv4.2 complexes through dipeptidyl aminopeptidase-like protein 6. J Biol Chem 2013; 288:37241-55. [PMID: 24225951 DOI: 10.1074/jbc.m113.488650] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Widely expressed in the adult central nervous system, the cellular prion protein (PrP(C)) is implicated in a variety of processes, including neuronal excitability. Dipeptidyl aminopeptidase-like protein 6 (DPP6) was first identified as a PrP(C) interactor using in vivo formaldehyde cross-linking of wild type (WT) mouse brain. This finding was confirmed in three cell lines and, because DPP6 directs the functional assembly of K(+) channels, we assessed the impact of WT and mutant PrP(C) upon Kv4.2-based cell surface macromolecular complexes. Whereas a Gerstmann-Sträussler-Scheinker disease version of PrP with eight extra octarepeats was a loss of function both for complex formation and for modulation of Kv4.2 channels, WT PrP(C), in a DPP6-dependent manner, modulated Kv4.2 channel properties, causing an increase in peak amplitude, a rightward shift of the voltage-dependent steady-state inactivation curve, a slower inactivation, and a faster recovery from steady-state inactivation. Thus, the net impact of wt PrP(C) was one of enhancement, which plays a critical role in the down-regulation of neuronal membrane excitability and is associated with a decreased susceptibility to seizures. Insofar as previous work has established a requirement for WT PrP(C) in the Aβ-dependent modulation of excitability in cholinergic basal forebrain neurons, our findings implicate PrP(C) regulation of Kv4.2 channels as a mechanism contributing to the effects of oligomeric Aβ upon neuronal excitability and viability.
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7
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Liao C, Fu F, Li R, Yang WQ, Liao HY, Yan JR, Li J, Li SY, Yang X, Li DZ. Loss-of-function variation in the DPP6 gene is associated with autosomal dominant microcephaly and mental retardation. Eur J Med Genet 2013; 56:484-9. [PMID: 23832105 DOI: 10.1016/j.ejmg.2013.06.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 06/27/2013] [Indexed: 11/26/2022]
Abstract
The molecular basis of autosomal dominant microcephaly, a disorder associated with small head circumferences that results in variable mental retardation, is largely unknown. In the present study, we conducted a variation analysis of the DPP6 gene in patients with autosomal dominant microcephaly and variable mental retardation. The copy number variation analysis of DPP6 was performed on DNA samples from 22 patients with microcephaly using high-resolution, array-based genomic hybridization, and sequence analysis was performed to screen mutations in another 50 microcephalic patients. Two de novo deletions and one missense mutation in familial microcephalic patients were identified. The transfection of plasmids encoding green fluorescent protein-pLLU2G-shDPP6 fusion proteins in mouse brains revealed that the decreased expression of the DPP6 gene slightly reduced the weight of the mouse brains and resulted in mouse learning disabilities compared with their wild-type littermates. Our data indicate that the loss-of-function variations in DPP6 are associated with autosomal dominant microcephaly and mental retardation. DPP6 appears to play a major role in the regulation of proliferation and migration of neurons in neurogenesis, most likely by participating in neuronal electrical excitability, synaptic integration, and plasticity.
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Affiliation(s)
- Can Liao
- Department of Medical Genetics, Guangzhou Women and Children's Medical Centre, Guangzhou Medical College, Guangzhou, China; Department of Molecular Biology, Guangzhou Medical College, Guangzhou, China.
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8
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Du J, Fan Z, Ma X, Wu Y, Liu S, Gao Y, Shen Y, Fan M, Wang S. Expression of DPP6 in Meckel's cartilage and tooth germs during mouse facial development. Biotech Histochem 2013; 89:14-8. [DOI: 10.3109/10520295.2013.795661] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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9
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Sheikh MA, Malik YS, Yu H, Lai M, Wang X, Zhu X. Epigenetic regulation of Dpp6 expression by Dnmt3b and its novel role in the inhibition of RA induced neuronal differentiation of P19 cells. PLoS One 2013; 8:e55826. [PMID: 23409053 PMCID: PMC3567024 DOI: 10.1371/journal.pone.0055826] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/02/2013] [Indexed: 12/05/2022] Open
Abstract
DNA methylation is an important mechanism of gene silencing in mammals catalyzed by a group of DNA methyltransferases including Dnmt1, Dnmt3a, and Dnmt3b which are required for the establishment of genomic methylation patterns during development and differentiation. In this report, we studied the role of DNA methyltransferases during retinoic acid induced neuronal differentiation of P19 cells. We observed an increase in the mRNA and protein level of Dnmt3b, whereas the expression of Dnmt1 and Dnmt3a was decreased after RA treatment of P19 cells which indicated that Dnmt3b is more important during neuronal differentiation of P19 cells. Dnmt3b enriched chromatin library from RA treated P19 cells identified dipeptidyl peptidase 6 (Dpp6) gene as a novel target of Dnmt3b. Further, quantitative ChIP analysis showed that the amount of Dnmt3b recruited on Dpp6 promoter was equal in both RA treated as well as untreated p19 cells. Bisulfite genomic sequencing, COBRA, and methylation specific PCR analysis revealed that Dpp6 promoter was heavily methylated in both RA treated and untreated P19 cells. Dnmt3b was responsible for transcriptional silencing of Dpp6 gene as depletion of Dnmt3b resulted in increased mRNA and protein expression of Dpp6. Consequently, the average methylation of Dpp6 gene promoter was reduced to half in Dnmt3b knockdown cells. In the absence of Dnmt3b, Dnmt3a was associated with Dpp6 gene promoter and regulated its expression and methylation in P19 cells. RA induced neuronal differentiation was inhibited upon ectopic expression of Dpp6 in P19 cells. Taken together, the present study described epigenetic silencing of Dpp6 expression by DNA methylation and established that its ectopic expression can act as negative signal during RA induced neuronal differentiation of P19 cells.
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Affiliation(s)
- Muhammad Abid Sheikh
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Yousra Saeed Malik
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Huali Yu
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Mingming Lai
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Xingzhi Wang
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Xiaojuan Zhu
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
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Witzel K, Fischer P, Bähring R. Hippocampal A-type current and Kv4.2 channel modulation by the sulfonylurea compound NS5806. Neuropharmacology 2012; 63:1389-403. [PMID: 22964468 DOI: 10.1016/j.neuropharm.2012.08.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/16/2012] [Accepted: 08/18/2012] [Indexed: 12/24/2022]
Abstract
We examined the effects of the sulfonylurea compound NS5806 on neuronal A-type channel function. Using whole-cell patch-clamp we studied the effects of NS5806 on the somatodendritic A-type current (I(SA)) in cultured hippocampal neurons and the currents mediated by Kv4.2 channels coexpressed with different auxiliary β-subunits, including both Kv channel interacting proteins (KChIPs) and dipeptidyl aminopeptidase-related proteins (DPPs), in HEK 293 cells. The amplitude of the I(SA) component in hippocampal neurons was reduced in the presence of 20 μM NS5806. I(SA) decay kinetics were slowed and the recovery kinetics accelerated, but the voltage dependence of steady-state inactivation was shifted to more negative potentials by NS5806. The peak amplitudes of currents mediated by ternary Kv4.2 channel complexes, associated with DPP6-S (short splice-variant) and either KChIP2, KChIP3 or KChIP4, were potentiated and their macroscopic inactivation slowed by NS5806, whereas the currents mediated by binary Kv4.2 channels, associated only with DPP6-S, were suppressed, and the NS5806-mediated slowing of macroscopic inactivation was less pronounced. Neither potentiation nor suppression and no effect on current decay kinetics in the presence of NS5806 were observed for Kv4.2 channels associated with KChIP3 and the N-type inactivation-conferring DPP6a splice-variant. For all recombinant channel complexes, NS5806 slowed the recovery from inactivation and shifted the voltage dependence of steady-state inactivation to more negative potentials. Our results demonstrate the activity of NS5806 on native I(SA) and possible molecular correlates in the form of recombinant Kv4.2 channels complexed with different KChIPs and DPPs, and they shed some light on the mechanism of NS5806 action.
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Affiliation(s)
- Katrin Witzel
- Institut für Zelluläre und Integrative Physiologie, Zentrum für Experimentelle Medizin, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
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11
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Du J, Fan Z, Ma X, Gao Y, Wu Y, Liu S, Shen Y, Fan M, Wang S. Expression of Dpp6 in mouse embryonic craniofacial development. Acta Histochem 2011; 113:636-9. [PMID: 20817268 DOI: 10.1016/j.acthis.2010.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/31/2010] [Accepted: 08/02/2010] [Indexed: 10/19/2022]
Abstract
Dipeptidyl-peptidase-like protein 6 (DPP6), a member of the dipeptidyl aminopeptidase family, plays distinct roles in brain development, but its expression in embryonic craniofacial development is unknown. The expression pattern of Dpp6 in the maxillofacial region during mouse embryonic craniofacial development was analyzed by whole-mount in situ hybridization on sections and by real-time PCR analysis. Dpp6 expression was detected during mouse embryonic craniofacial development in embryos 11-13.5 days post-coitum (dpc). Real-time PCR showed high Dpp6 expression present in 11.5-13.5dpc, and this then decreased as development of maxillofacial region progressed. The expression pattern of Dpp6 suggests that Dpp6 may be involved in embryonic craniofacial development.
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Abstract
One of the most straightforward approaches to making novel biological discoveries is the forward genetic screen. The time is ripe for forward genetic screens in the mouse since the mouse genome is sequenced, but the function of many of the genes remains unknown. Today, with careful planning, such screens are within the reach of even small individual labs. In this chapter we first discuss the types of screens in existence, as well as how to design a screen to recover mutations that are relevant to the interests of a lab. We then describe how to create mutations using the chemical N-ethyl-N-nitrosourea (ENU), including a detailed injection protocol. Next, we outline breeding schemes to establish mutant lines for each type of screen. Finally, we explain how to map mutations using recombination and how to ensure that a particular mutation causes a phenotype. Our goal is to make forward genetics in the mouse accessible to any lab with the desire to do it.
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Affiliation(s)
- Vanessa L Horner
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA.
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13
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Abstract
Since the first discovery of Kvbeta-subunits more than 15 years ago, many more ancillary Kv channel subunits were characterized, for example, KChIPs, KCNEs, and BKbeta-subunits. The ancillary subunits are often integral parts of native Kv channels, which, therefore, are mostly multiprotein complexes composed of voltage-sensing and pore-forming Kvalpha-subunits and of ancillary or beta-subunits. Apparently, Kv channels need the ancillary subunits to fulfill their many different cell physiological roles. This is reflected by the large structural diversity observed with ancillary subunit structures. They range from proteins with transmembrane segments and extracellular domains to purely cytoplasmic proteins. Ancillary subunits modulate Kv channel gating but can also have a great impact on channel assembly, on channel trafficking to and from the cellular surface, and on targeting Kv channels to different cellular compartments. The importance of the role of accessory subunits is further emphasized by the number of mutations that are associated in both humans and animals with diseases like hypertension, epilepsy, arrhythmogenesis, periodic paralysis, and hypothyroidism. Interestingly, several ancillary subunits have in vitro enzymatic activity; for example, Kvbeta-subunits are oxidoreductases, or modulate enzymatic activity, i.e., KChIP3 modulates presenilin activity. Thus different modes of beta-subunit association and of functional impact on Kv channels can be delineated, making it difficult to extract common principles underlying Kvalpha- and beta-subunit interactions. We critically review present knowledge on the physiological role of ancillary Kv channel subunits and their effects on Kv channel properties.
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Affiliation(s)
- Olaf Pongs
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Universität Hamburg, Hamburg, Germany.
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14
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Jerng HH, Dougherty K, Covarrubias M, Pfaffinger PJ. A novel N-terminal motif of dipeptidyl peptidase-like proteins produces rapid inactivation of KV4.2 channels by a pore-blocking mechanism. Channels (Austin) 2009; 3:448-61. [PMID: 19901547 DOI: 10.4161/chan.3.6.10216] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The somatodendritic subthreshold A-type K(+) current in neurons (I(SA)) depends on its kinetic and voltage-dependent properties to regulate membrane excitability, action potential repetitive firing, and signal integration. Key functional properties of the K(V)4 channel complex underlying I(SA) are determined by dipeptidyl peptidase-like proteins known as dipeptidyl peptidase 6 (DPP6) and dipeptidyl peptidase 10 (DPP10). Among the multiple known DPP10 isoforms with alternative N-terminal sequences, DPP10a confers exceptionally fast inactivation to K(V)4.2 channels. To elucidate the molecular basis of this fast inactivation, we investigated the structure-function relationship of the DPP10a N-terminal region and its interaction with the K(V)4.2 channel. Here, we show that DPP10a shares a conserved N-terminal sequence (MNQTA) with DPP6a (aka DPP6-E), which also induces fast inactivation. Deletion of the NQTA sequence in DPP10a eliminates this dramatic fast inactivation, and perfusion of MNQTA peptide to the cytoplasmic face of inside-out patches inhibits the K(V)4.2 current. DPP10a-induced fast inactivation exhibits competitive interactions with internally applied tetraethylammonium (TEA), and elevating the external K(+) concentration accelerates recovery from DPP10a-mediated fast inactivation. These results suggest that fast inactivation induced by DPP10a or DPP6a is mediated by a common N-terminal inactivation motif via a pore-blocking mechanism. This mechanism may offer an attractive target for novel pharmacological interventions directed at impairing I(SA) inactivation and reducing neuronal excitability.
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Affiliation(s)
- Henry H Jerng
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
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15
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McNicholas K, Chen T, Abbott CA. Dipeptidyl peptidase (DP) 6 and DP10: novel brain proteins implicated in human health and disease. Clin Chem Lab Med 2009; 47:262-7. [PMID: 19676137 DOI: 10.1515/cclm.2009.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Dipeptidyl peptidase (DP) 6 and DP10 are non-enzyme members of the dipeptidyl peptidase IV family, which includes fibroblast activation protein, DP8, and DP9. DP6 and DP10 proteins have been shown to be critical components of voltage-gated potassium (Kv) channels important in determining cellular excitability. The aim of this paper was to review the research to date on DP6 and DP10 structure, expression, and functions. To date, the protein region responsible for modulating Kv4 channels has not been conclusively identified and the significance of the splice variants has not been resolved. Resolution of these issues will improve our overall knowledge of DP6 and DP10 and lead to a better understanding of their role in diseases, such as asthma and Alzheimer's disease.
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Affiliation(s)
- Kym McNicholas
- School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia
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Katayama K, Furuno A, Miyamoto S, Nakamura M, Ojika I, Shinkai Y, Akiyama K, Tsuji T, Kunieda T. Suppressed recombination on mouse chromosome 15 defined regions of chromosomal inversions associated with koala (koa) and hairy ears (eh) mutations. Exp Anim 2008; 57:73-7. [PMID: 18256521 DOI: 10.1538/expanim.57.73] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Koala (Koa) and hairy ears (Eh) mutations of mice are associated with chromosomal inversions in the distal half of chromosome 15. Since these two mutant mice show some common phenotypic features including extra hair on pinna and craniofacial dysmorphogenesis and have similar inverted regions, we determined the inverted regions of these two chromosomal inversions to examine whether a common gene is responsible for the phenotypes of these two mutants. The inverted regions were identified as the recombination-suppressed regions by linkage analysis. The length of the recombination-suppressed regions of Koa and Eh were approximately 52 and 47 Mb, respectively, and these inverted regions were not the same. These results indicate that the phenotypes of Koa and Eh mutant mice are likely to be caused by different genes.
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Affiliation(s)
- Kentaro Katayama
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
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17
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Brooks SA, Lear TL, Adelson DL, Bailey E. A chromosome inversion near the KIT gene and the Tobiano spotting pattern in horses. Cytogenet Genome Res 2008; 119:225-30. [PMID: 18253033 DOI: 10.1159/000112065] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2007] [Indexed: 10/22/2022] Open
Abstract
Tobiano is a white spotting pattern in horses caused by a dominant gene, Tobiano(TO). Here, we report TO associated with a large paracentric chromosome inversion on horse chromosome 3. DNA sequences flanking the inversion were identified and a PCR test was developed to detect the inversion. The inversion was only found in horses with the tobiano pattern, including horses with diverse genetic backgrounds, which indicated a common genetic origin thousands of years ago. The inversion does not interrupt any annotated genes, but begins approximately 100 kb downstream of the KIT gene. This inversion may disrupt regulatory sequences for the KIT gene and cause the white spotting pattern.
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Affiliation(s)
- S A Brooks
- Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
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18
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KIT is required for hepatic function during mouse post-natal development. BMC DEVELOPMENTAL BIOLOGY 2007; 7:81. [PMID: 17612398 PMCID: PMC1940254 DOI: 10.1186/1471-213x-7-81] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2006] [Accepted: 07/05/2007] [Indexed: 12/13/2022]
Abstract
Background The Kit gene encodes a receptor tyrosine kinase involved in various biological processes including melanogenesis, hematopoiesis and gametogenesis in mice and human. A large number of Kit mutants has been described so far showing the pleiotropic phenotypes associated with partial loss-of-function of the gene. Hypomorphic mutations can induce a light coat color phenotype while complete lack of KIT function interferes with embryogenesis. Interestingly several intermediate hypomorphic mutations induced in addition growth retardation and post-natal mortality. Results In this report we investigated the post-natal role of Kit by using a panel of chemically-induced hypomorphic mutations recently isolated in the mouse. We found that, in addition to the classical phenotypes, mutations of Kit induced juvenile steatosis, associated with the downregulation of the three genes, VldlR, Lpin1 and Lpl, controlling lipid metabolism in the post-natal liver. Hence, Kit loss-of-functions mimicked the inactivation of genes controlling the hepatic metabolism of triglycerides, the major source of energy from maternal milk, leading to growth and viability defects during neonatal development. Conclusion This is a first report involving KIT in the control of lipid metabolism in neonates and opening new perspectives for understanding juvenile steatosis. Moreover, it reinforces the role of Kit during development of the liver and underscores the caution that should be exerted in using KIT inhibitors during anti-cancer treatment.
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Katayama K, Furuno A, Akiyama K, Tsuji T, Kunieda T. Characterization of chromosomal inversion of the mouse hairy ears (Eh) mutation associated with cleft palate. Mamm Genome 2007; 18:246-54. [PMID: 17520166 DOI: 10.1007/s00335-007-9015-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Revised: 03/19/2007] [Accepted: 03/21/2007] [Indexed: 01/27/2023]
Abstract
The hairy ears (Eh) mutation in the mouse originated from neutron irradiation experiments and is associated with chromosomal inversion on chromosome 15. Eh/+ mice have small pinna and extra hairs on the pinna but the phenotypic features of Eh/Eh mice are unclear. In this study we found that Eh/Eh mice died shortly after birth and had a cleft palate caused by impaired growth of palate shelves. Because genes located on the breakpoints of inversion are likely to be responsible for the defects associated with chromosomal inversions, we determined the breakpoints of the Eh inversion. We used a new genetic method that uses recombinant chromosomes resulting from crossing over between two overlapping inversions to determine the breakpoints. Koa is a mouse mutation associated with inversion of chromosome 15, which partially overlaps with the Eh inversion. We made Eh +/+ Koa double heterozygotes and obtained the recombinant chromosomes possessing deletion and duplication of the regions flanked by the breakpoints of both inversions, which were generated by crossing over within the overlapped region of these inversions. By defining the deleted regions we identified the breakpoints of the Eh inversion. We then examined the expression of genes in the vicinities of the breakpoints and found ectopic expression of the Hoxc5 gene and a transcript with unknown function in the developing palate of Eh/Eh mice, which is likely to be responsible for the cleft palate.
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Affiliation(s)
- Kentaro Katayama
- Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Okayama 700-8530, Japan
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20
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Jerng HH, Lauver AD, Pfaffinger PJ. DPP10 splice variants are localized in distinct neuronal populations and act to differentially regulate the inactivation properties of Kv4-based ion channels. Mol Cell Neurosci 2007; 35:604-24. [PMID: 17475505 PMCID: PMC3674967 DOI: 10.1016/j.mcn.2007.03.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 12/20/2006] [Accepted: 03/16/2007] [Indexed: 10/23/2022] Open
Abstract
Dipeptidyl peptidase-like proteins (DPLs) and Kv-channel-interacting proteins (KChIPs) join Kv4 pore-forming subunits to form multi-protein complexes that underlie subthreshold A-type currents (I(SA)) in neuronal somatodendritic compartments. Here, we characterize the functional effects and brain distributions of N-terminal variants belonging to the DPL dipeptidyl peptidase 10 (DPP10). In the Kv4.2+KChIP3+DPP10 channel complex, all DPP10 variants accelerate channel gating kinetics; however, the splice variant DPP10a produces uniquely fast inactivation kinetics that accelerates with increasing depolarization. This DPP10a-specific inactivation dominates in co-expression studies with KChIP4a and other DPP10 isoforms. Real-time qRT-PCR and in situ hybridization analyses reveal differential expression of DPP10 variants in rat brain. DPP10a transcripts are prominently expressed in the cortex, whereas DPP10c and DPP10d mRNAs exhibit more diffuse distributions. Our results suggest that DPP10a underlies rapid inactivation of cortical I(SA), and the regulation of isoform expression may contribute to the variable inactivation properties of I(SA) across different brain regions.
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Affiliation(s)
- Henry H Jerng
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, S630 Houston, TX 77030, USA.
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Gorrell MD, Wang XM, Park J, Ajami K, Yu DMT, Knott H, Seth D, McCaughan GW. Structure and Function in Dipeptidyl Peptidase IV and Related Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 575:45-54. [PMID: 16700507 DOI: 10.1007/0-387-32824-6_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Mark D Gorrell
- A. W. Morrow Gastroenterology and Liver Centre at Royal Prince Alfred Hospital, Centenary Institute of Cancer Medicine and Cell Biology and The Discipline of Medicine, University of Sydney, Sydney, New South Wales, Australia
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22
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Takimoto K, Hayashi Y, Ren X, Yoshimura N. Species and tissue differences in the expression of DPPY splicing variants. Biochem Biophys Res Commun 2006; 348:1094-100. [PMID: 16899223 DOI: 10.1016/j.bbrc.2006.07.157] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2006] [Accepted: 07/26/2006] [Indexed: 11/29/2022]
Abstract
The non-functional dipeptidyl peptidase, DPPY (DPP10), regulates the expression and gating of K+ channels in Kv4 family by tightly binding to these pore-forming subunits. Neural tissue-specific expression of this and the related DPPX (DPP6) is thought to confer rapid inactivation and other unique properties of neuronal Kv4 channels. Here we report that DPPY mRNA is abundant in human adrenal gland, but very low in the corresponding rat tissue. Furthermore, multiple DPPY splicing variants with alternative first exons are significant in the brain, whereas the expression of DPPY gene in the adrenal gland and pancreas is predominantly initiated at the two latter sites. These splicing variants, as well as an N-terminal peptide-deleted DPPY, produce similar changes in Kv4.3 gating. Thus, transcription of DPPY gene is species- and tissue-specifically controlled.
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Affiliation(s)
- Koichi Takimoto
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, 100 Technology Drive, Pittsburgh, PA 15260, USA.
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23
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Nadal MS, Amarillo Y, Vega-Saenz de Miera E, Rudy B. Differential characterization of three alternative spliced isoforms of DPPX. Brain Res 2006; 1094:1-12. [PMID: 16764835 DOI: 10.1016/j.brainres.2006.03.106] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 03/13/2006] [Accepted: 03/22/2006] [Indexed: 11/17/2022]
Abstract
Transient subthreshold-activating somato-dendritic A-type K(+) currents (I(SA)s) have fundamental roles in neuronal function. They cause delayed excitation, influence spike repolarization, modulate the frequency of repetitive firing, and have important roles in signal processing in dendrites. We previously reported that DPPX proteins are key components of the channels mediating these currents (Kv4 channels) (Nadal, M.S., Ozaita, A., Amarillo, Y., Vega-Saenz, E., Ma, Y., Mo, W., Goldberg, E.M., Misumi, Y., Ikehara, Y., Neubert, T.A., Rudy, B., 2003. The CD26-related dipeptidyl aminopeptidase-like protein DPPX is a critical component of neuronal A-type K+ channels. Neuron 37, 449-461). The DPPX gene encodes alternatively spliced transcripts that generate single-spanning transmembrane proteins with a short, divergent intracellular domain and a large extracellular domain. We characterized the modulatory effects on Kv4.2-mediated currents and the rat brain distribution of three splice variants of the DPPX subfamily of proteins. These three splice isoforms--DPPX-S, DPPX-L, and DPPX-K--are expressed in adult rat brain and modify the voltage dependence and kinetic properties of Kv4.2 channels expressed in Xenopus oocytes. Analysis of a deletion mutant that lacks the variable N-terminus showed that the N-terminus is not necessary for the modulation of Kv4 channels. Using in situ hybridization analysis, we found that the three splice variants are prominently expressed in brain regions where Kv4 subunits are also expressed. DPPX-K and DPPX-S mRNAs have a widespread distribution, whereas DPPX-L transcripts are concentrated in few specific areas of the rat brain. The emerging diversity of DPPX splice variants, differing only in the N-terminus of the protein, opens up intriguing possibilities for the modulation of Kv4 channels.
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Affiliation(s)
- Marcela S Nadal
- Department of Physiology and Neuroscience, New York University School of Medicine, New York, NY 10016, USA
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Chen T, Ajami K, McCaughan GW, Gai WP, Gorrell MD, Abbott CA. Molecular characterization of a novel dipeptidyl peptidase like 2-short form (DPL2-s) that is highly expressed in the brain and lacks dipeptidyl peptidase activity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:33-43. [PMID: 16290253 DOI: 10.1016/j.bbapap.2005.09.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 09/24/2005] [Accepted: 09/28/2005] [Indexed: 10/25/2022]
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.
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Affiliation(s)
- Tong Chen
- School of Biological Sciences, Flinders University, GPO BOX 2100, Adelaide, South Australia 5001, Australia
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25
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Jerng HH, Kunjilwar K, Pfaffinger PJ. Multiprotein assembly of Kv4.2, KChIP3 and DPP10 produces ternary channel complexes with ISA-like properties. J Physiol 2005; 568:767-88. [PMID: 16123112 PMCID: PMC1464192 DOI: 10.1113/jphysiol.2005.087858] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 08/22/2005] [Indexed: 01/04/2023] Open
Abstract
Kv4 pore-forming subunits are the principal constituents of the voltage-gated K+ channel underlying somatodendritic subthreshold A-type currents (I(SA)) in neurones. Two structurally distinct types of Kv4 channel modulators, Kv channel-interacting proteins (KChIPs) and dipeptidyl-peptidase-like proteins (DPLs: DPP6 or DPPX, DPP10 or DPPY), enhance surface expression and modify functional properties. Since KChIP and DPL distributions overlap in the brain, we investigated the potential coassembly of Kv4.2, KChIP3 and DPL proteins, and the contribution of DPLs to ternary complex properties. Immunoprecipitation results show that KChIP3 and DPP10 associate simultaneously with Kv4.2 proteins in rat brain as well as heterologously expressing Xenopus oocytes, indicating Kv4.2 + KChIP3 + DPP10 multiprotein complexes. Consistent with ternary complex formation, coexpression of Kv4.2, KChIP3 and DPP10 in oocytes and CHO cells results in current waveforms distinct from the arithmetic sum of Kv4.2 + KChIP3 and Kv4.2 + DPP10 currents. Furthermore, the Kv4.2 + KChIP3 + DPP10 channels recover from inactivation very rapidly (tau(rec) approximately 18-26 ms), closely matching that of native I(SA) and significantly faster than the recovery of Kv4.2 + KChIP3 or Kv4.2 + DPP10 channels. For comparison, identical triple coexpression experiments were performed using DPP6 variants. While most results are similar, the Kv4.2 + KChIP3 + DPP6 channels exhibit inactivation that slows with increasing membrane potential, resulting in inactivation slower than that of Kv4.2 + KChIP3 + DPP10 channels at positive voltages. In conclusion, the native neuronal subthreshold A-type channel is probably a macromolecular complex formed from Kv4 and a combination of both KChIP and DPL proteins, with the precise composition of channel alpha and auxiliary subunits underlying tissue and regional variability in I(SA) properties.
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Affiliation(s)
- Henry H Jerng
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, S630, Houston, TX 77030, USA.
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Wilson L, Ching YH, Farias M, Hartford SA, Howell G, Shao H, Bucan M, Schimenti JC. Random mutagenesis of proximal mouse chromosome 5 uncovers predominantly embryonic lethal mutations. Genome Res 2005; 15:1095-105. [PMID: 16024820 PMCID: PMC1182222 DOI: 10.1101/gr.3826505] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A region-specific ENU mutagenesis screen was conducted to elucidate the functional content of proximal mouse Chr 5. We used the visibly marked, recessive, lethal inversion Rump White (Rw) as a balancer in a three-generation breeding scheme to identify recessive mutations within the approximately 50 megabases spanned by Rw. A total of 1003 pedigrees were produced, representing the largest inversion screen performed in mice. Test-class animals, homozygous for the ENU-mutagenized proximal Chr 5 and visibly distinguishable from nonhomozygous littermates, were screened for fertility, hearing, vestibular function, DNA repair, behavior, and dysmorphology. Lethals were identifiable by failure to derive test-class animals within a pedigree. Embryonic lethal mutations (total of 34) were overwhelmingly the largest class of mutants recovered. We characterized them with respect to the time of embryonic death, revealing that most act at midgestation (8.5-10.5) or sooner. To position the mutations within the Rw region and to guide allelism tests, we performed complementation analyses with a set of new and existing chromosomal deletions, as well as standard recombinational mapping on a subset of the mutations. By pooling the data from this and other region-specific mutagenesis projects, we calculate that the mouse genome contains approximately 3479-4825 embryonic lethal genes, or about 13.7%-19% of all genes.
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Robinson KO, Petersen AM, Morrison SN, Elso CM, Stubbs L. Two reciprocal translocations provide new clues to the high mutability of the Grid2 locus. Mamm Genome 2005; 16:32-40. [PMID: 15674731 DOI: 10.1007/s00335-004-2423-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 09/23/2004] [Indexed: 11/28/2022]
Abstract
We describe two new mutations, 153Gso and 154Gso, associated with reciprocal translocations with a common breakpoint in mouse chromosome 6B3 (Mmu6B3). The translocations arose independently in offspring of male mice treated with chlorambucil and glycidamide, respectively. Homozygotes of both mutant stocks display a characteristic gait ataxia with 'foot-patting' behavior; despite their ataxia the mutant animals are healthy, long-lived, and breed normally. Breeding experiments confirmed that 153Gso and 154Gso mutations are allelic, and both fail to complement a known mutation hotfoot (ho), a Mmu6 mutation involving the glutamate receptor gene, Grid2, that is associated with a virtually identical phenotype. Our studies demonstrate that the 153Gso and 154Gso mutations disrupt the Grid2 gene at sites located more than 100 kb apart in intron 6 and intron 4 of the gene, respectively. The occurrence of two independent translocations from a relatively small colony within the same locus supports data suggesting the hypermutability of the Grid2 locus and suggest that the gene's large size make it an especially likely target for mutations involving genetic rearrangement.
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Affiliation(s)
- Kellie O Robinson
- Genome Biology Division, Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, L-441, 7000 East Avenue, Livermore, California, 94550, USA
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Gorrell MD. Dipeptidyl peptidase IV and related enzymes in cell biology and liver disorders. Clin Sci (Lond) 2005; 108:277-92. [PMID: 15584901 DOI: 10.1042/cs20040302] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
DP (dipeptidyl peptidase) IV is the archetypal member of its six-member gene family. Four members of this family, DPIV, FAP (fibroblast activation protein), DP8 and DP9, have a rare substrate specificity, hydrolysis of a prolyl bond two residues from the N-terminus. The ubiquitous DPIV glycoprotein has proved interesting in the fields of immunology, endocrinology, haematology and endothelial cell and cancer biology and DPIV has become a novel target for Type II diabetes therapy. The crystal structure shows that the soluble form of DPIV comprises two domains, an alpha/beta-hydrolase domain and an eight-blade beta-propeller domain. The propeller domain contains the ADA (adenosine deaminase) binding site, a dimerization site, antibody epitopes and two openings for substrate access to the internal active site. FAP is structurally very similar to DPIV, but FAP protein expression is largely confined to diseased and damaged tissue, notably the tissue remodelling interface in chronically injured liver. DPIV has a variety of peptide substrates, the best studied being GLP-1 (glucagon-like peptide-1), NPY (neuropeptide Y) and CXCL12. The DPIV family has roles in bone marrow mobilization. The functional interactions of DPIV and FAP with extracellular matrix confer roles for these proteins in cancer biology. DP8 and DP9 are widely distributed and indirectly implicated in immune function. The DPL (DP-like) glycoproteins that lack peptidase activity, DPL1 and DPL2, are brain-expressed potassium channel modulators. Thus the six members of the DPIV gene family exhibit diverse biological roles.
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Affiliation(s)
- Mark D Gorrell
- A.W. Morrow Gastroenterology and Liver Centre at Royal Prince Alfred Hospital, Centenary Institute of Cancer Medicine and Cell Biology and Discipline of Medicine, The University of Sydney, Sydney, New South Wales, Australia.
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Jerng HH, Pfaffinger PJ, Covarrubias M. Molecular physiology and modulation of somatodendritic A-type potassium channels. Mol Cell Neurosci 2005; 27:343-69. [PMID: 15555915 DOI: 10.1016/j.mcn.2004.06.011] [Citation(s) in RCA: 239] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2004] [Revised: 05/22/2004] [Accepted: 06/08/2004] [Indexed: 11/23/2022] Open
Abstract
The somatodendritic subthreshold A-type K+ current (ISA) in nerve cells is a critical component of the ensemble of voltage-gated ionic currents that determine somatodendritic signal integration. The underlying K+ channel belongs to the Shal subfamily of voltage-gated K+ channels. Most Shal channels across the animal kingdom share a high degree of structural conservation, operate in the subthreshold range of membrane potentials, and exhibit relatively fast inactivation and recovery from inactivation. Mammalian Shal K+ channels (Kv4) undergo preferential closed-state inactivation with features that are generally inconsistent with the classical mechanisms of inactivation typical of Shaker K+ channels. Here, we review (1) the physiological and genetic properties of ISA, 2 the molecular mechanisms of Kv4 inactivation and its remodeling by a family of soluble calcium-binding proteins (KChIPs) and a membrane-bound dipeptidase-like protein (DPPX), and (3) the modulation of Kv4 channels by protein phosphorylation.
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Affiliation(s)
- Henry H Jerng
- Division of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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Strop P, Bankovich AJ, Hansen KC, Garcia KC, Brunger AT. Structure of a Human A-type Potassium Channel Interacting Protein DPPX, a Member of the Dipeptidyl Aminopeptidase Family. J Mol Biol 2004; 343:1055-65. [PMID: 15476821 DOI: 10.1016/j.jmb.2004.09.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Revised: 08/20/2004] [Accepted: 09/02/2004] [Indexed: 11/23/2022]
Abstract
It has recently been reported that dipeptidyl aminopeptidase X (DPPX) interacts with the voltage-gated potassium channel Kv4 and that co-expression of DPPX together with Kv4 pore forming alpha-subunits, and potassium channel interacting proteins (KChIPs), reconstitutes properties of native A-type potassium channels in vitro. Here we report the X-ray crystal structure of the extracellular domain of human DPPX determined at 3.0A resolution. This structure reveals the potential for a surface electrostatic change based on the protonation state of histidine. Subtle changes in extracellular pH might modulate the interaction of DPPX with Kv4.2 and possibly with other proteins. We propose models of DPPX interaction with the voltage-gated potassium channel complex. The dimeric structure of DPPX is highly homologous to the related protein DPP-IV. Comparison of the active sites of DPPX and DPP-IV reveals loss of the catalytic serine residue but the presence of an additional serine near the "active" site. However, the arrangement of residues is inconsistent with that of canonical serine proteases and DPPX is unlikely to function as a protease (dipeptidyl aminopeptidase).
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Affiliation(s)
- Pavel Strop
- Howard Hughes Medical Institute and Department of Molecular and Cellular Physiology, Stanford Synchrotron Radiation Laboratory, Stanford University, James H. Clark Center E300, 318 Campus Drive, Stanford, CA 94305, USA
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Puig M, Cáceres M, Ruiz A. Silencing of a gene adjacent to the breakpoint of a widespread Drosophila inversion by a transposon-induced antisense RNA. Proc Natl Acad Sci U S A 2004; 101:9013-8. [PMID: 15184654 PMCID: PMC428464 DOI: 10.1073/pnas.0403090101] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adaptive changes in nature occur by a variety of mechanisms, and Drosophila chromosomal inversions was one of the first studied examples. However, the precise genetic causes of the adaptive value of inversions remain uncertain. Here we investigate the impact of the widespread inversion 2j of Drosophila buzzatii on the expression of the CG13617 gene, whose coding region is located only 12 bp away from the inversion proximal breakpoint. This gene is transcribed into a 2.3-kb mRNA present in all D. buzzatii developmental stages. More importantly, the expression level of CG13617 is reduced 5-fold in embryos of lines homozygous for the 2j inversion compared with lines without the inversion. An antisense RNA that originates in the Foldback-like transposon Kepler inserted at the breakpoint junction in all of the 2j lines and that forms duplexes with the CG13617 mRNA in 2j embryos is most likely responsible for the near silencing of the gene. Few examples of RNA interference caused by transposable elements (TEs) have been previously described, but this mechanism might be prevalent in many organisms and illustrates the potential of TEs as a major source of genetic variation. In addition, because chromosomal rearrangements are usually induced by TEs, position effects might be more common than previously recognized and contribute significantly to the evolutionary success of inversions.
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Affiliation(s)
- Marta Puig
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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Rosenblum JS, Kozarich JW. Prolyl peptidases: a serine protease subfamily with high potential for drug discovery. Curr Opin Chem Biol 2003; 7:496-504. [PMID: 12941425 DOI: 10.1016/s1367-5931(03)00084-x] [Citation(s) in RCA: 234] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Much attention has recently been given to a class of proteases that cleave proteins and peptides after proline residues. This class includes dipeptidyl peptidase IV (DPP IV; also termed CD26), fibroblast activation protein alpha (FAP; seprase), DPP7 (DPP II; quiescent cell proline dipeptidase), DPP8, DPP9, and prolyl carboxypeptidase (PCP; angiotensinase C). More distant members include prolyl oligopeptidase (POP; post proline cleaving enzyme) and acylaminoacylpeptidase (AAP; acylpeptide hydrolase). The DPPs and related proteins contain both membrane-bound and soluble members and span a broad range of expression patterns, tissue distributions and compartmentalization. These proteins have important roles in regulation of signaling by peptide hormones, and are emerging targets for diabetes, oncology and other indications.
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Chen T, Ajami K, McCaughan GW, Gorrell MD, Abbott CA. Dipeptidyl peptidase IV gene family. The DPIV family. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 524:79-86. [PMID: 12675227 DOI: 10.1007/0-306-47920-6_10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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.
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Affiliation(s)
- Tong Chen
- School of Biological Sciences, Flinders University of South Australia, Adelaide, Australia
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Wehrle-Haller B. The role of Kit-ligand in melanocyte development and epidermal homeostasis. PIGMENT CELL RESEARCH 2003; 16:287-96. [PMID: 12753403 DOI: 10.1034/j.1600-0749.2003.00055.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Kit-ligand (Kitl) also known as steel factor, stem cell factor and mast cell growth factor plays a crucial role in the development and maintenance of the melanocyte lineage in adult skin. Kitl exerts permanent survival, proliferation and migration functions in Kit receptor-expressing melanocytes. A comprehensive overview over the differential roles of Kitl in melanocyte development and homeostasis is provided. I discuss species-specific differences of the Kitl/Kit signalling system, regulation at the transcriptional level and also covering the regulation of cell surface Kitl presentation by cytoplasmic targeting sequences. In addition, recent studies evoked the importance of Kitl misexpression in some hyperpigmented lesions that may open the avenue for Kitl-dependent treatment of pathological skin conditions.
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Nadal MS, Ozaita A, Amarillo Y, Vega-Saenz de Miera E, Ma Y, Mo W, Goldberg EM, Misumi Y, Ikehara Y, Neubert TA, Rudy B. The CD26-related dipeptidyl aminopeptidase-like protein DPPX is a critical component of neuronal A-type K+ channels. Neuron 2003; 37:449-61. [PMID: 12575952 DOI: 10.1016/s0896-6273(02)01185-6] [Citation(s) in RCA: 265] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Subthreshold-activating somatodendritic A-type potassium channels have fundamental roles in neuronal signaling and plasticity which depend on their unique cellular localization, voltage dependence, and kinetic properties. Some of the components of A-type K(+) channels have been identified; however, these do not reproduce the properties of the native channels, indicating that key molecular factors have yet to be unveiled. We purified A-type K(+) channel complexes from rat brain membranes and found that DPPX, a protein of unknown function that is structurally related to the dipeptidyl aminopeptidase and cell adhesion protein CD26, is a novel component of A-type K(+) channels. DPPX associates with the channels' pore-forming subunits, facilitates their trafficking and membrane targeting, reconstitutes the properties of the native channels in heterologous expression systems, and is coexpressed with the pore-forming subunits in the somatodendritic compartment of CNS neurons.
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Affiliation(s)
- Marcela S Nadal
- Department of Physiology and Neuroscience and Department of Biochemistry, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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Abstract
CD26/DPPIV can be considered a moonlighting protein because it is a multifunctional protein that exerts its different functions depending on cell type and intra- or extracellular conditions in which it is expressed. In the present review, we summarize all its known functions in relation to physiological and pathophysiological conditions. The protein is a proteolytic enzyme, receptor, costimulatory protein, and is involved in adhesion and apoptosis. The CD26/DPPIV protein plays a major role in immune response. Abnormal expression is found in the case of autoimmune diseases, HIV-related diseases and cancer. Natural substrates for CD26/DPPIV are involved in immunomodulation, psycho/neuronal modulation and physiological processes in general. Therefore, targeting of CD26/ DPPIV and especially its proteolytic activity has many therapeutic potentials. On the other hand, there are homologous proteins with overlapping proteolytic activity, which thus may prevent specific modulation of CD26/DPPIV. In conclusion, CD26/DPPIV is a protein present both in various cellular compartments and extracellularly where it exerts different functions and thus is a true moonlighting protein.
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Affiliation(s)
- Emil Boonacker
- Academic Medical Center, University of Amsterdam, Department of Cell Biology and Histology, Amsterdam, The Netherlands
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Sedo A, Malík R. Dipeptidyl peptidase IV-like molecules: homologous proteins or homologous activities? BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1550:107-16. [PMID: 11755200 DOI: 10.1016/s0167-4838(01)00278-3] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Membrane-bound proteases are widely distributed among various cell systems. Their expression in a particular cell type is finely regulated, reflecting the specific functional cell implications and engagement in defined physiological pathways. Protein turnover, ontogeny, inflammation, tissue remodeling, cell migration and tumor invasion are among the many physiological and pathological events in which membrane proteases play a crucial role, both as effector as well as regulatory molecules. The presence of proline residues gives unique structural features to peptide chains, substantially influencing the susceptibility of proximal peptide bond to protease cleavage. Among the rare group of proline-specific proteases, dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) was originally believed to be the only membrane-bound enzyme specific for proline as the penultimate residue at the amino-terminus of the polypeptide chain. However, other molecules, even structurally non-homologous with the DPP-IV but bearing corresponding enzyme activity, have been identified recently. This review summarizes the present knowledge of "DPP-IV activity- and/or structure-homologues" (DASH) and provides some insight into their multifunctional roles.
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Affiliation(s)
- A Sedo
- Joint Laboratory of Cancer Cell Biology of the First Faculty of Medicine, First Department of Medical Chemistry and Biochemistry, Charles University, Katerinská 32, 121 08 Prague 2, Czech Republic.
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Abbott CA, Yu DM, Woollatt E, Sutherland GR, McCaughan GW, Gorrell MD. Cloning, expression and chromosomal localization of a novel human dipeptidyl peptidase (DPP) IV homolog, DPP8. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:6140-50. [PMID: 11012666 DOI: 10.1046/j.1432-1327.2000.01617.x] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Dipeptidyl peptidase (DPP) IV has roles in T-cell costimulation, chemokine biology, type-II diabetes and tumor biology. Fibroblast activation protein (FAP) has been implicated in tumor growth and cirrhosis. Here we describe DPP8, a novel human postproline dipeptidyl aminopeptidase that is homologous to DPPIV and FAP. Northern-blot hybridization showed that the tissue expression of DPP8 mRNA is ubiquitous, similar to that of DPPIV. The DPP8 gene was localized to chromosome 15q22, distinct from a closely related gene at 19p13.3 which we named DPP9. The full-length DPP8 cDNA codes for an 882-amino-acid protein that has about 27% identity and 51% similarity to DPPIV and FAP, but no transmembrane domain and no N-linked or O-linked glycosylation. Western blots and confocal microscopy of transfected COS-7 cells showed DPP8 to be a 100-kDa monomeric protein expressed in the cytoplasm. Purified recombinant DPP8 hydrolyzed the DPPIV substrates Ala-Pro, Arg-Pro and Gly-Pro. Thus recombinant DPP8 shares a postproline dipeptidyl aminopeptidase activity with DPPIV and FAP. DPP8 enzyme activity had a neutral pH optimum consistent with it being nonlysosomal. The similarities between DPP8 and DPPIV in tissue expression pattern and substrates suggests a potential role for DPP8 in T-cell activation and immune function.
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Affiliation(s)
- C A Abbott
- A. W. Morrow Gastroenterology and Liver Centre, Royal Prince Alfred Hospital, Centenary Institute of Cancer Medicine and Cell Biologyand The University of Sydney, NSW, Australia.
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Schimenti JC, Libby BJ, Bergstrom RA, Wilson LA, Naf D, Tarantino LM, Alavizadeh A, Lengeling A, Bucan M. Interdigitated deletion complexes on mouse chromosome 5 induced by irradiation of embryonic stem cells. Genome Res 2000; 10:1043-50. [PMID: 10899153 PMCID: PMC310891 DOI: 10.1101/gr.10.7.1043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Chromosome deletions have several applications in the genetic analysis of complex organisms. They can be used as reagents in region-directed mutagenesis, for mapping of simple or complex traits, or to identify biological consequences of segmental haploidy, the latter being relevant to human contiguous gene syndromes and imprinting. We have generated three deletion complexes in ES (Embryonic Stem) cells that collectively span approximately 40 cM of proximal mouse chromosome 5. The deletion complexes were produced by irradiation of F(1) hybrid ES cells containing herpes simplex virus thymidine kinase genes (tk) integrated at the Dpp6, Hdh (Huntington disease locus), or Gabrb1 loci, followed by selection for tk-deficient clones. Deletions centered at the adjacent Hdh and Dpp6 loci ranged up to approximately 20 cM or more in length and overlapped in an interdigitated fashion. However, the interval between Hdh and Gabrb1 appeared to contain a locus haploinsufficient for ES cell viability, thereby preventing deletions of either complex from overlapping. In some cases, the deletions resolved the order of markers that were previously genetically inseparable. A subset of the ES cell-bearing deletions was injected into blastocysts to generate germline chimeras and establish lines of mice segregating the deletion chromosomes. At least 11 of the 26 lines injected were capable of producing germline chimeras. In general, those that failed to undergo germline transmission bore deletions larger than the germline-competent clones, suggesting that certain regions of chromosome 5 contain haploinsufficient developmental genes, and/or that overall embryonic viability is cumulatively decreased as more genes are rendered hemizygous. Mice bearing deletions presumably spanning the semidominant hammertoe locus (Hm) had no phenotype, suggesting that the classic allele is a dominant, gain-of-function mutation. Overlapping deletion complexes generated in the fashion described in this report will be useful as multipurpose genetic tools and in systematic functional mapping of the mouse genome.
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Affiliation(s)
- J C Schimenti
- The Jackson Laboratory, Bar Harbor, Maine 04609 USA.
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Jordan SA, Jackson IJ. A late wave of melanoblast differentiation and rostrocaudal migration revealed in patch and rump-white embryos. Mech Dev 2000; 92:135-43. [PMID: 10727853 DOI: 10.1016/s0925-4773(99)00332-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Melanocytes originate from a small number of precursors localized either side of the dorsal midline. The tyrosine kinase receptor Kit and its ligand Mgf (Steel Factor) are essential for melanoblast survival and proliferation during their migration from the neural crest. Inappropriate Kit expression in the dermatome and dermis of patch and rump-white mouse mutants apparently sequester Mgf, inhibiting melanoblast dispersal. Using a reporter transgene Dct-lacZ, extensive regions of the mutant trunks appear devoid of melanoblasts between E12.5 and E15.5, a much larger area than seen in mutant adults. Melanoblast recolonization of the underpopulated lumbar regions occurs very rapidly by E16.5 giving rise to patterns consistent with those observed in adults. The mutations permit observation of aspects of melanoblast development that are not seen, or are obscured, in normal embryos.
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Affiliation(s)
- S A Jordan
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, UK.
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Zhao S, Overbeek PA. Tyrosinase-related protein 2 promoter targets transgene expression to ocular and neural crest-derived tissues. Dev Biol 1999; 216:154-63. [PMID: 10588869 DOI: 10.1006/dbio.1999.9480] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In an effort to identify a promoter suitable for studying early ocular development, we generated transgenic mice carrying the lacZ reporter gene linked to the tyrosinase-related protein 2 (TRP2) promoter. TRP2-lacZ was expressed in early retinal pigment epithelium (RPE) and early neural crest cells in embryos. The promoter activity was robust and consistent in independent transgenic lines. The transgene was also expressed in the optic nerve and neural crest-derived neuronal cells in which the endogenous TRP2 gene is not expressed. This suggests that repressor elements may be missing in the promoter used in this study. To test whether this promoter can be used to study melanocyte development, we cross-mated TRP2-lacZ transgenic mice with mice heterozygous for the Patch (Ph) mutation. The pattern of beta-galactosidase activity in the embryos correlates well with the pigmentation phenotype in postnatal and adult Ph/+ mice. We also generated transgenic mice expressing fibroblast growth factor 9 (FGF9) directed by the TRP2 promoter and examined the effect on ocular development. Ectopic expression of FGF9 in the early embryonic RPE switched its differentiation pathway to a neuronal fate, resulting in formation of a duplicated neural retina in transgenic mice. These studies demonstrate that the TRP2 promoter is valuable for transgenic studies of ocular differentiation and development of neural crest cells.
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Affiliation(s)
- S Zhao
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
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Abstract
White spotting is the absence of melanocytes (pigment cells) from part or all of the locations in the body where they are normally found. At least in the case of the W (kit) locus, white spotting has been attributed to apoptosis. In addition to the death of melanoblasts, white spotting might result from their failure to migrate to their normal locations. These developmental failures are known to be melanocyte-specific in some instances and environment-specific in others. The environment is defined as the tissues surrounding the melanoblast. Patterns of white spotting were examined on mice mutant at the piebald (s), patch (Ph), dominant spotting (W(J2)) rumpwhite (Rw) or belted (bt) loci. The dominant spotting locus has been cloned and found to encode KIT; it has been suggested that Patch encodes the linked alpha-PDGF receptor. Piebald encodes the endothelin beta receptor. In each case, the phenotypes expressed when the allele was backcrossed onto one inbred strain C57BL/6 (B6), were compared with phenotypes expressed when the allele was backcrossed onto a different inbred strain, JU/CtLm (JU). The literature documents genetic loci that influence the extent of the white spotted area; we herein demonstrate that genetic loci also influence the location where the white spot (absence of melanocytes) will occur over the body of the mouse. Spotting occurs in a more anterior direction on JU mice that are piebald, patch or dominant-spotted compared with similar B6 mice. The relationship is reversed in rumpwhite mice, where white spotting is more anterior in the C57BL/6 mice than in the JU mice. The spotting pattern of belted mice was not modified by the background genome. Thus, the Mendelian observations indicate that several loci, which differ in JU compared with B6 mice, influence the size and the location of white spots on the mouse.
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Affiliation(s)
- M L Lamoreux
- Department of Veterinary Pathobiology, Texas A&M University, College Station 77843, USA.
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The Wsh, W57, and Ph Kit Expression Mutations Define Tissue-Specific Control Elements Located Between −23 and −154 kb Upstream of Kit. Blood 1999. [DOI: 10.1182/blood.v94.8.2658.420k23_2658_2666] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Kit and PDGFRa receptor tyrosine kinases are encoded in close proximity at the murine white spotting (W) and patch (Ph) loci. Whereas W mutations affect hematopoiesis, melanogenesis, and gametogenesis, the Ph mutation affects melanogenesis and causes early lethality in homozygotes. TheWsh, W57, and Phmutations diminish Kit expression in certain cell types such as mast cells and enhance it in others. The Wsh,W57, and Ph mutations arose from deletions and inversions affecting sequences in between the Kit andPDGFRa genes. We have determined the precise location of the breakpoint of the Wshinversion and the endpoints of the W57deletion upstream of the Kittranscription start site and examined the effect of these mutations on Kit expression in mast cells and hematopoietic stem cells and lineage progenitors. Our results indicate that positive elements controlling Kit expression in mast cells mapping in between −23 and −154 kb from the transcription start site can be dissociated from negative elements controlling Kit misexpression during embryonic development in the vicinity of the PDGFRa gene. In addition, we have identified two clusters of hypersensitive sites in mast cells at −23 −28 kb and −147 −154 kb from the Kit gene transcription start site. Analysis of these hypersensitive sites in mutant mast cells indicates a role for HS4-6 in Kit expression in mast cells. These findings provide a molecular basis for the phenotype of these Kit expression mutations and they provide insight into the complex mechanisms governing the regulation ofKit expression.
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Abstract
The analyses of transgenic and knockout mice with perturbations in alpha 1 connexin (Cx43) function have revealed an important role for gap junctions in cardiac development. This likely involves the modulation of cardiac crest migration and function. Studies carried out with these mouse models suggest that clinically there may be a novel category of cardiac defects involving crest perturbations that do not include outflow septation defects, but rather involve more subtle defects in the pulmonary outflow tract.
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Affiliation(s)
- C W Lo
- Biology Department, University of Pennsylvania, Philadelphia 19104, USA
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Gourdie RG, Lo CW. Chapter 26: Cx43 (α1) Gap Junctions in Cardiac Development and Disease. CURRENT TOPICS IN MEMBRANES 1999. [DOI: 10.1016/s0070-2161(08)61030-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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