1
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Fricker LD, Lemos Duarte M, Jeltyi A, Lueptow L, Fakira AK, Tashima AK, Hochgeschwender U, Wetsel WC, Devi LA. Mice heterozygous for a null mutation of Cpe show reduced expression of carboxypeptidase E mRNA and enzyme activity but normal physiology, behavior, and levels of neuropeptides. Brain Res 2022; 1789:147951. [PMID: 35618016 DOI: 10.1016/j.brainres.2022.147951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 11/02/2022]
Abstract
Carboxypeptidase E (CPE) is an essential enzyme that contributes to the biosynthesis of the vast majority of neuropeptides and peptide hormones. There are several reports claiming that small decreases in CPE activity cause physiological changes in animals and/or cultured cells, but these studies did not provide evidence that neuropeptide levels were affected by decreased CPE activity. In the present study, we tested if CPE is a rate-limiting enzyme in neuropeptide production using CpeNeo mice, which contain a neomycin cassette within the Cpe gene that eliminates enzyme expression. Homozygous CpeNeo/Neo mice show defects found in Cpefat/fat and/or Cpe global knockout (KO) mice, including greatly decreased levels of most neuropeptides, severely impaired fertility, depressive-like behavior, adult-onset obesity, and anxiety-like behavior. Removal of the neomycin cassette with Flp recombinase under a germline promoter restored expression of CPE activity and resulted in normal behavioral and physiological properties, including levels of neuropeptides. Mice heterozygous for the CpeNeo allele have greatly reduced levels of Cpe mRNA and CPE-like enzymatic activity. Despite the decreased levels of Cpe expression, heterozygous CpeNeo mice are behaviorally and physiologically identical to wild-type mice, with normal levels of most neuropeptides. These results indicate that CPE is not a rate-limiting enzyme in the production of most neuropeptides, casting doubt upon studies claiming small decreases in CPE activity contribute to obesity or other physiological effects.
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Affiliation(s)
- Lloyd D Fricker
- Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461.
| | - Mariana Lemos Duarte
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, NY, NY, 10029.
| | - Andrei Jeltyi
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, NY, NY, 10029.
| | - Lindsay Lueptow
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, NY, NY, 10029.
| | - Amanda K Fakira
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, NY, NY, 10029.
| | - Alexandre K Tashima
- Department of Biochemistry, Escola Paulista de Medicina, Federal University of Sao Paulo, Sao Paulo, SP 04023-901, Brazil.
| | | | - William C Wetsel
- Departments of Psychiatry and Behavioral Sciences, Neurobiology, and Cell Biology, Duke University Medical Center, Durham, NC, 27710.
| | - Lakshmi A Devi
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, NY, NY, 10029.
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2
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Zheng JM, Zhou HX, Yu HY, Xia YH, Yu QX, Qu HS, Bao JQ. By Increasing the Expression and Activation of STAT3, Sustained C5a Stimulation Increases the Proliferation, Migration, and Invasion of RCC Cells and Promotes the Growth of Transgrafted Tumors. Cancer Manag Res 2021; 13:7607-7621. [PMID: 34675657 PMCID: PMC8500505 DOI: 10.2147/cmar.s326352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 09/11/2021] [Indexed: 11/23/2022] Open
Abstract
Background Contradictive results about the direct role of C5a/C5aR1 axis in different cancer cells have been reported. The direct effect of C5a on human renal cell carcinoma (RCC) cells and the underlying mechanism are not clear. The aim of this study is to investigate the role of C5a/C5aR1 axis in RCC cells and its working mechanism. Methods RCC cells were infected with lentivirus Lenti-C5a, which was designed to over-express secretory C5a in the cells, or directly treated with recombinant C5a, the influence of these treatments in the cells and the underlying mechanism were explored. Results Transfection of RCC cells with Lenti-C5a markedly increased the production of C5a and significantly increased the proliferation, migration, and invasion of RCC cells, but direct addition of C5a to the cell culture medium had no such effects though it indeed induced a transient intracellular calcium rise. RCC cells were found to express carboxypeptidase D and M, which reportedly to inactivate C5a. Also, the RCC cells stably transfected with Lenti-C5a produced larger transgrafted tumors in nude mice compared with the non-transfected or control virus transfected cells. In addition, over-expression of C5a significantly increased the expression and phosphorylation of STAT3 as well as the phosphorylated JNK level. Furthermore, the effect of C5a over-expression on RCC cells' proliferation, migration, and invasion could be blocked by Stattic, a STAT3-specific inhibitor. Conclusion Chronic over-activation of C5a/C5aR1 axis could directly increase RCC cells' proliferation, migration, and invasion and thus contribute directly to the progression of the disease. Over-activation of STAT3 pathway is among the underlying mechanism.
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Affiliation(s)
- Jing-Min Zheng
- Department of Urology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
| | - Han-Xi Zhou
- Department of Urology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
| | - Hong-Yuan Yu
- Department of Urology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
| | - Yu-Hui Xia
- Department of Pathology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
| | - Qing-Xin Yu
- Department of Pathology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
| | - Hang-Shuai Qu
- Department of Urology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
| | - Jia-Qian Bao
- Department of Urology, Taizhou Hospital, Wenzhou Medical University, Linhai, Zhejiang, People's Republic of China
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3
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Abid MSR, Mousavi S, Checco JW. Identifying Receptors for Neuropeptides and Peptide Hormones: Challenges and Recent Progress. ACS Chem Biol 2021; 16:251-263. [PMID: 33539706 DOI: 10.1021/acschembio.0c00950] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Intercellular signaling events mediated by neuropeptides and peptide hormones represent important targets for both basic science and drug discovery. For many bioactive peptides, the protein receptors that transmit information across the receiving cell membrane are not known, severely limiting these signaling pathways as potential therapeutic targets. Identifying the receptor(s) for a given peptide of interest is complicated by several factors. Most notably, cell-cell signaling peptides are generated through dynamic biosynthetic pathways, can act on many different families of receptor proteins, and can participate in complex ligand-receptor interactions that extend beyond a simple one-to-one archetype. Here, we discuss recent methodological advances to identify signaling partners for bioactive peptides. Recent efforts have centered on methods to identify candidate receptors via transcript expression, methods to match peptide-receptor pairs through high throughput screening, and methods to capture direct ligand-receptor interactions using chemical probes. Future applications of the receptor identification approaches discussed here, as well as technical advancements to address their limitations, promise to lead to a greater understanding of how cells communicate to deliver complex physiologies. Importantly, such advancements will likely provide novel targets for the treatment of human diseases within the central nervous and endocrine systems.
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Affiliation(s)
- Md Shadman Ridwan Abid
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Somayeh Mousavi
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - James W. Checco
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
- The Nebraska Center for Integrated Biomolecular Communication (NCIBC), University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
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4
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CRISPR screens in cancer spheroids identify 3D growth-specific vulnerabilities. Nature 2020; 580:136-141. [PMID: 32238925 PMCID: PMC7368463 DOI: 10.1038/s41586-020-2099-x] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 01/10/2020] [Indexed: 12/18/2022]
Abstract
Cancer genomics studies have nominated thousands of putative cancer
driver genes1; a major
challenge is to develop high-throughput and accurate models to define their
functions. Here we devised a scalable cancer spheroid model and performed
genome-wide CRISPR screens in 2D-monolayers and 3D lung cancer spheroids. CRISPR
phenotypes in 3D more accurately recapitulate those of in vivo
tumors, and genes with differential sensitivities between 2D and 3D are strongly
enriched for significant mutations in lung cancers. These analyses also revealed
novel drivers essential for cancer growth in 3D and in vivo,
but not in 2D. Notably, we discovered that CPD (Carboxypeptidase D) is
responsible for removal of a c-terminal RKRR motif2 of IGF1R α-chain, critical for
receptor activity. CPD expression correlates with patient outcomes in lung
cancer, and loss of CPD reduced tumor growth. Our results reveal key differences
between 2D and 3D cancer models, and establish a generalizable strategy to
perform CRISPR screens in spheroids to uncover cancer vulnerabilities.
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Corbière A, Vaudry H, Chan P, Walet-Balieu ML, Lecroq T, Lefebvre A, Pineau C, Vaudry D. Strategies for the Identification of Bioactive Neuropeptides in Vertebrates. Front Neurosci 2019; 13:948. [PMID: 31619945 PMCID: PMC6759750 DOI: 10.3389/fnins.2019.00948] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 08/22/2019] [Indexed: 11/13/2022] Open
Abstract
Neuropeptides exert essential functions in animal physiology by controlling e.g., reproduction, development, growth, energy homeostasis, cardiovascular activity and stress response. Thus, identification of neuropeptides has been a very active field of research over the last decades. This review article presents the various methods used to discover novel bioactive peptides in vertebrates. Initially identified on the basis of their biological activity, some neuropeptides have also been discovered for their ability to bind/activate a specific receptor or based on their biochemical characteristics such as C-terminal amidation which concerns half of the known neuropeptides. More recently, sequencing of the genome of many representative species has facilitated peptidomic approaches using mass spectrometry and in silico screening of genomic libraries. Through these different approaches, more than a hundred of bioactive neuropeptides have already been identified in vertebrates. Nevertheless, researchers continue to find new neuropeptides or to identify novel functions of neuropeptides that had not been detected previously, as it was recently the case for nociceptin.
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Affiliation(s)
- Auriane Corbière
- Normandie Univ, UNIROUEN, Inserm, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Neuropeptides, Neuronal Death and Cell Plasticity Team, Rouen, France
| | - Hubert Vaudry
- Normandie Univ, UNIROUEN, Inserm, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Neuropeptides, Neuronal Death and Cell Plasticity Team, Rouen, France.,Normandie Univ, UNIROUEN, Regional Cell Imaging Platform of Normandy (PRIMACEN), Rouen, France
| | - Philippe Chan
- Normandie Univ, UNIROUEN, Rouen Proteomic Platform (PISSARO), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Marie-Laure Walet-Balieu
- Normandie Univ, UNIROUEN, Rouen Proteomic Platform (PISSARO), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Thierry Lecroq
- Normandie Univ, UNIROUEN, LITIS EA 4108, Information Processing in Biology & Health, Rouen, France
| | - Arnaud Lefebvre
- Normandie Univ, UNIROUEN, LITIS EA 4108, Information Processing in Biology & Health, Rouen, France
| | | | - David Vaudry
- Normandie Univ, UNIROUEN, Inserm, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Neuropeptides, Neuronal Death and Cell Plasticity Team, Rouen, France.,Normandie Univ, UNIROUEN, Regional Cell Imaging Platform of Normandy (PRIMACEN), Rouen, France.,Normandie Univ, UNIROUEN, Rouen Proteomic Platform (PISSARO), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
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6
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Pauls D, Hamarat Y, Trufasu L, Schendzielorz TM, Gramlich G, Kahnt J, Vanselow JT, Schlosser A, Wegener C. Drosophila carboxypeptidase D (SILVER) is a key enzyme in neuropeptide processing required to maintain locomotor activity levels and survival rate. Eur J Neurosci 2019; 50:3502-3519. [PMID: 31309630 DOI: 10.1111/ejn.14516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/19/2019] [Accepted: 07/05/2019] [Indexed: 11/27/2022]
Abstract
Neuropeptides are processed from larger preproproteins by a dedicated set of enzymes. The molecular and biochemical mechanisms underlying preproprotein processing and the functional importance of processing enzymes are well-characterised in mammals, but little studied outside this group. In contrast to mammals, Drosophila melanogaster lacks a gene for carboxypeptidase E (CPE), a key enzyme for mammalian peptide processing. By combining peptidomics and neurogenetics, we addressed the role of carboxypeptidase D (dCPD) in global neuropeptide processing and selected peptide-regulated behaviours in Drosophila. We found that a deficiency in dCPD results in C-terminally extended peptides across the peptidome, suggesting that dCPD took over CPE function in the fruit fly. dCPD is widely expressed throughout the nervous system, including peptidergic neurons in the mushroom body and neuroendocrine cells expressing adipokinetic hormone. Conditional hypomorphic mutation in the dCPD-encoding gene silver in the larva causes lethality, and leads to deficits in starvation-induced hyperactivity and appetitive gustatory preference, as well as to reduced viability and activity levels in adults. A phylogenomic analysis suggests that loss of CPE is not common to insects, but only occurred in Hymenoptera and Diptera. Our results show that dCPD is a key enzyme for neuropeptide processing and peptide-regulated behaviour in Drosophila. dCPD thus appears as a suitable target to genetically shut down total neuropeptide production in peptidergic neurons. The persistent occurrence of CPD in insect genomes may point to important further CPD functions beyond neuropeptide processing which cannot be fulfilled by CPE.
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Affiliation(s)
- Dennis Pauls
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Yasin Hamarat
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany.,'Santaka' Valley I Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Luisa Trufasu
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Tim M Schendzielorz
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Gertrud Gramlich
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Jörg Kahnt
- Max-Planck-Institute of Terrestrial Microbiology, Marburg, Germany
| | - Jens T Vanselow
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Andreas Schlosser
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Christian Wegener
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
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7
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Pimsler ML, Sze S, Saenz S, Fu S, Tomberlin JK, Tarone AM. Gene expression correlates of facultative predation in the blow fly Chrysomya rufifacies (Diptera: Calliphoridae). Ecol Evol 2019; 9:8690-8701. [PMID: 31410272 PMCID: PMC6686648 DOI: 10.1002/ece3.5413] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 05/26/2019] [Accepted: 05/27/2019] [Indexed: 11/17/2022] Open
Abstract
Effects of intraguild predation (IGP) on omnivores and detritivores are relatively understudied when compared to work on predator guilds. Functional genetic work in IGP is even more limited, but its application can help answer a range of questions related to ultimate and proximate causes of this behavior. Here, we integrate behavioral assays and transcriptomic analysis of facultative predation in a blow fly (Diptera: Calliphoridae) to evaluate the prevalence, effect, and correlated gene expression of facultative predation by the invasive species Chrysomya rufifacies. Field work observing donated human cadavers indicated facultative predation by C. rufifacies on the native blow fly Cochliomyia macellaria was rare under undisturbed conditions, owing in part to spatial segregation between species. Laboratory assays under conditions of starvation showed predation had a direct fitness benefit (i.e., survival) to the predator. As a genome is not available for C. rufifacies, a de novo transcriptome was developed and annotated using sequence similarity to Drosophila melanogaster. Under a variety of assembly parameters, several genes were identified as being differentially expressed between predators and nonpredators of this species, including genes involved in cell-to-cell signaling, osmotic regulation, starvation responses, and dopamine regulation. Results of this work were integrated to develop a model of the processes and genetic regulation controlling facultative predation.
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Affiliation(s)
- Meaghan L. Pimsler
- Department of EntomologyTexas A&M UniversityCollege StationTexasUSA
- Department of Biological SciencesUniversity of AlabamaTuscaloosaAlabamaUSA
| | - Sing‐Hoi Sze
- Department of Computer Science and EngineeringTexas A&M UniversityCollege StationTexasUSA
| | - Sunday Saenz
- Department of EntomologyTexas A&M UniversityCollege StationTexasUSA
- Federal Aviation AdministrationFederal Government OfficeTulsaOklahomaUSA
| | - Shuhua Fu
- Department of Biochemistry & BiophysicsTexas A&M UniversityCollege StationTexasUSA
- Department of Developmental BiologyWashington University School of Medicine in St. LouisSt. LouisMissouriUSA
| | | | - Aaron M. Tarone
- Department of EntomologyTexas A&M UniversityCollege StationTexasUSA
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8
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Van Bael S, Watteyne J, Boonen K, De Haes W, Menschaert G, Ringstad N, Horvitz HR, Schoofs L, Husson SJ, Temmerman L. Mass spectrometric evidence for neuropeptide-amidating enzymes in Caenorhabditis elegans. J Biol Chem 2018; 293:6052-6063. [PMID: 29487130 DOI: 10.1074/jbc.ra117.000731] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 02/18/2018] [Indexed: 12/18/2022] Open
Abstract
Neuropeptides constitute a vast and functionally diverse family of neurochemical signaling molecules and are widely involved in the regulation of various physiological processes. The nematode Caenorhabditis elegans is well-suited for the study of neuropeptide biochemistry and function, as neuropeptide biosynthesis enzymes are not essential for C. elegans viability. This permits the study of neuropeptide biosynthesis in mutants lacking certain neuropeptide-processing enzymes. Mass spectrometry has been used to study the effects of proprotein convertase and carboxypeptidase mutations on proteolytic processing of neuropeptide precursors and on the peptidome in C. elegans However, the enzymes required for the last step in the production of many bioactive peptides, the carboxyl-terminal amidation reaction, have not been characterized in this manner. Here, we describe three genes that encode homologs of neuropeptide amidation enzymes in C. elegans and used tandem LC-MS to compare neuropeptides in WT animals with those in newly generated mutants for these putative amidation enzymes. We report that mutants lacking both a functional peptidylglycine α-hydroxylating monooxygenase and a peptidylglycine α-amidating monooxygenase had a severely altered neuropeptide profile and also a decreased number of offspring. Interestingly, single mutants of the amidation enzymes still expressed some fully processed amidated neuropeptides, indicating the existence of a redundant amidation mechanism in C. elegans All MS data are available via ProteomeXchange with the identifier PXD008942. In summary, the key steps in neuropeptide processing in C. elegans seem to be executed by redundant enzymes, and loss of these enzymes severely affects brood size, supporting the need of amidated peptides for C. elegans reproduction.
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Affiliation(s)
- Sven Van Bael
- From the Department of Biology, KU Leuven (University of Leuven), Naamsestraat 59, B-3000 Leuven, Belgium,
| | - Jan Watteyne
- From the Department of Biology, KU Leuven (University of Leuven), Naamsestraat 59, B-3000 Leuven, Belgium
| | - Kurt Boonen
- From the Department of Biology, KU Leuven (University of Leuven), Naamsestraat 59, B-3000 Leuven, Belgium
| | - Wouter De Haes
- From the Department of Biology, KU Leuven (University of Leuven), Naamsestraat 59, B-3000 Leuven, Belgium
| | - Gerben Menschaert
- the Laboratory of Bioinformatics and Computational Genomics (BioBix), Department of Mathematical Modelling, Ghent University, B-9000 Ghent, Belgium
| | - Niels Ringstad
- The Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU Langone Medical Center, New York, New York 10016
| | - H Robert Horvitz
- the Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and
| | - Liliane Schoofs
- From the Department of Biology, KU Leuven (University of Leuven), Naamsestraat 59, B-3000 Leuven, Belgium
| | - Steven J Husson
- SPHERE-Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Liesbet Temmerman
- From the Department of Biology, KU Leuven (University of Leuven), Naamsestraat 59, B-3000 Leuven, Belgium,
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9
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Garcia-Pardo J, Tanco S, Díaz L, Dasgupta S, Fernandez-Recio J, Lorenzo J, Aviles FX, Fricker LD. Substrate specificity of human metallocarboxypeptidase D: Comparison of the two active carboxypeptidase domains. PLoS One 2017; 12:e0187778. [PMID: 29131831 PMCID: PMC5683605 DOI: 10.1371/journal.pone.0187778] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/25/2017] [Indexed: 11/18/2022] Open
Abstract
Metallocarboxypeptidase D (CPD) is a membrane-bound component of the trans-Golgi network that cycles to the cell surface through exocytic and endocytic pathways. Unlike other members of the metallocarboxypeptidase family, CPD is a multicatalytic enzyme with three carboxypeptidase-like domains, although only the first two domains are predicted to be enzymatically active. To investigate the enzymatic properties of each domain in human CPD, a critical active site Glu in domain I and/or II was mutated to Gln and the protein expressed, purified, and assayed with a wide variety of peptide substrates. CPD with all three domains intact displays >50% activity from pH 5.0 to 7.5 with a maximum at pH 6.5, as does CPD with mutation of domain I. In contrast, the domain II mutant displayed >50% activity from pH 6.5–7.5. CPD with mutations in both domains I and II was completely inactive towards all substrates and at all pH values. A quantitative peptidomics approach was used to compare the activities of CPD domains I and II towards a large number of peptides. CPD cleaved C-terminal Lys or Arg from a subset of the peptides. Most of the identified substrates of domain I contained C-terminal Arg, whereas comparable numbers of Lys- and Arg-containing peptides were substrates of domain II. We also report that some peptides with C-terminal basic residues were not cleaved by either domain I or II, showing the importance of the P1 position for CPD activity. Finally, the preference of domain I for C-terminal Arg was validated through molecular docking experiments. Together with the differences in pH optima, the different substrate specificities of CPD domains I and II allow the enzyme to perform distinct functions in the various locations within the cell.
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Affiliation(s)
- Javier Garcia-Pardo
- Institut de Biotecnologia i Biomedicina and Departament de Bioquimica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Sebastian Tanco
- Institut de Biotecnologia i Biomedicina and Departament de Bioquimica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
- VIB-UGent Center for Medical Biotechnology, Ghent, Belgium
- Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Lucía Díaz
- Barcelona Supercomputing Center (BSC), Joint BSC-CRG-IRB Research Program in Computational Biology, Life Sciences Department, Barcelona, Spain
| | - Sayani Dasgupta
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Juan Fernandez-Recio
- Barcelona Supercomputing Center (BSC), Joint BSC-CRG-IRB Research Program in Computational Biology, Life Sciences Department, Barcelona, Spain
| | - Julia Lorenzo
- Institut de Biotecnologia i Biomedicina and Departament de Bioquimica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Francesc X. Aviles
- Institut de Biotecnologia i Biomedicina and Departament de Bioquimica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
- * E-mail: (LDF); (FXA)
| | - Lloyd D. Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail: (LDF); (FXA)
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10
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Fricker LD. Carboxypeptidase E and the Identification of Novel Neuropeptides as Potential Therapeutic Targets. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 82:85-102. [PMID: 29413529 DOI: 10.1016/bs.apha.2017.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Peptides and small molecules that bind to peptide receptors are important classes of drugs that are used for a wide variety of different applications. The search for novel neuropeptides traditionally involved a time-consuming approach to purify each peptide to homogeneity and determine its amino acid sequence. The discovery in the 1980s of enkephalin convertase/carboxypeptidase E (CPE), and the observation that this enzyme was involved in the production of nearly every known neuropeptide led to the idea for a one-step affinity purification of CPE substrates. This approach was successfully used to isolate hundreds of known neuropeptides in mouse brain, as well as over a dozen novel peptides. Some of the novel peptides found using this approach are among the most abundant peptides present in brain, but had not been previously identified by traditional approaches. Recently, receptors for two of the novel peptides have been identified, confirming their role as neuropeptides that function in cell-cell signaling. Small molecules that bind to one of these receptors have been developed and found to significantly reduce food intake and anxiety-like behavior in an animal model. This review describes the entire project, from discovery of CPE to the novel peptides and their receptors.
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Affiliation(s)
- Lloyd D Fricker
- Albert Einstein College of Medicine, Bronx, NY, United States.
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11
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Ji L, Wu HT, Qin XY, Lan R. Dissecting carboxypeptidase E: properties, functions and pathophysiological roles in disease. Endocr Connect 2017; 6:R18-R38. [PMID: 28348001 PMCID: PMC5434747 DOI: 10.1530/ec-17-0020] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 03/27/2017] [Indexed: 01/02/2023]
Abstract
Since discovery in 1982, carboxypeptidase E (CPE) has been shown to be involved in the biosynthesis of a wide range of neuropeptides and peptide hormones in endocrine tissues, and in the nervous system. This protein is produced from pro-CPE and exists in soluble and membrane forms. Membrane CPE mediates the targeting of prohormones to the regulated secretory pathway, while soluble CPE acts as an exopeptidase and cleaves C-terminal basic residues from peptide intermediates to generate bioactive peptides. CPE also participates in protein internalization, vesicle transport and regulation of signaling pathways. Therefore, in two types of CPE mutant mice, Cpefat/Cpefat and Cpe knockout, loss of normal CPE leads to a lot of disorders, including diabetes, hyperproinsulinemia, low bone mineral density and deficits in learning and memory. In addition, the potential roles of CPE and ΔN-CPE, an N-terminal truncated form, in tumorigenesis and diagnosis were also addressed. Herein, we focus on dissecting the pathophysiological roles of CPE in the endocrine and nervous systems, and related diseases.
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Affiliation(s)
- Lin Ji
- Department of Cell Biology & Medical GeneticsSchool of Medicine, Shenzhen University, Shenzhen, China
| | - Huan-Tong Wu
- Beijing Engineering Research Center of Food Environment and HealthCollege of Life & Environmental Sciences, Minzu University of China, Beijing, China
| | - Xiao-Yan Qin
- Beijing Engineering Research Center of Food Environment and HealthCollege of Life & Environmental Sciences, Minzu University of China, Beijing, China
| | - Rongfeng Lan
- Department of Cell Biology & Medical GeneticsSchool of Medicine, Shenzhen University, Shenzhen, China
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Prolactin/androgen-inducible carboxypeptidase-D increases with nitrotyrosine and Ki67 for breast cancer progression in vivo, and upregulates progression markers VEGF-C and Runx2 in vitro. Breast Cancer Res Treat 2017; 164:27-40. [PMID: 28364216 DOI: 10.1007/s10549-017-4223-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 03/24/2017] [Indexed: 12/19/2022]
Abstract
PURPOSE Carboxypeptidase-D (CPD) cleaves C-terminal arginine (Arg) to produce nitric oxide (NO). Upregulation of CPD and NO by 17β-estradiol, prolactin (PRL), and androgen increases survival of human breast cancer (BCa) cells in vitro. To demonstrate similar events in vivo, CPD, nitrotyrosine (NT, hallmark of NO action), androgen receptor (AR), prolactin receptor (PRLR), and phospho-Stat5a (for activated PRLR) levels were evaluated in benign and malignant human breast tissues, and correlated with cell proliferation (Ki67) and BCa progression (Cullin-3) biomarkers. METHODS Paraffin-embedded breast tissues were analyzed by immunohistochemistry (IHC). BCa progression markers in human MCF-7 and T47D BCa cell lines treated with NO donor SIN-1 or PRL, ±CPD inhibitors were analyzed by RT-qPCR and immunoblotting. RESULTS IHC showed progressive increases in CPD, NT, Ki67, and Cullin-3 from low levels in benign tissues to high levels in ductal carcinoma in situ, low-grade, high-grade, and triple-negative BCa. CPD and NT staining were closely associated, implicating CPD in NO production. Phospho-Stat5a increased significantly from benign to high-grade BCa and was mostly nuclear. AR and PRLR were abundant in benign breast and BCa, including triple-negative tumors. SIN-1 and PRL increased VEGF-C and Runx2, but not Cullin-3, in BCa cell lines. PRL induction of VEGF-C and Runx2 was inhibited partly by CPD inhibitors, implicating NO, produced by PRL-regulated CPD, in BCa progression. CONCLUSIONS The CPD-Arg-NO pathway contributes to BCa progression in vitro and in vivo. PRL/androgen activation of the pathway support combined AR and PRLR blockade as an additional therapy for BCa.
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Thomas LN, Merrimen J, Bell DG, Rendon R, Too CKL. Prolactin- and testosterone-induced carboxypeptidase-D correlates with increased nitrotyrosines and Ki67 in prostate cancer. Prostate 2015. [PMID: 26202060 DOI: 10.1002/pros.23054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Carboxypeptidase-D (CPD) cleaves C-terminal arginine for conversion to nitric oxide (NO) by nitric oxide synthase (NOS). Prolactin (PRL) and androgens stimulate CPD gene transcription and expression, which increases intracellular production of NO to promote viability of prostate cancer (PCa) cells in vitro. The current study evaluated whether hormonal upregulation of CPD and NO promote PCa cell viabilty in vivo, by correlating changes in expression of CPD and nitrotyrosine residues (products of NO action) with proliferation marker Ki67 and associated proteins during PCa development and progression. METHODS Fresh prostate tissues, obtained from 40 men with benign prostatic hyperplasia (BPH) or PCa, were flash-frozen at the time of surgery and used for RT-qPCR analysis of CPD, androgen receptor (AR), PRL receptor (PRLR), eNOS, and Ki67 levels. Archival paraffin-embedded tissues from 113 men with BPH or PCa were used for immunohistochemical (IHC) analysis of CPD, nitrotyrosines, phospho-Stat5 (for activated PRLR), AR, eNOS/iNOS, and Ki67. RESULTS RT-qPCR and IHC analyses showed strong AR and PRLR expression in benign and malignant prostates. CPD mRNA levels increased ∼threefold in PCa compared to BPH, which corresponded to a twofold increase in Ki67 mRNA levels. IHC analysis showed a progressive increase in CPD from 11.4 ± 2.1% in benign to 21.8 ± 3.2% in low-grade (P = 0.007), 40.7 ± 4.0% in high-grade (P < 0.0001) and 50.0 ± 9.5% in castration-recurrent PCa (P < 0.0001). Immunostaining for nitrotyrosines and Ki67 mirrored these increases during PCa progression. CPD, nitrotyrosines, and Ki67 tended to co-localize, as did phospho-Stat5. CONCLUSIONS CPD, nitrotyrosine, and Ki67 levels were higher in PCa than in benign and tended to co-localize, along with phospho-Stat5. The strong correlation in expression of these proteins in benign and malignant prostate tissues, combined with abundant AR and PRLR, supports in vitro evidence that the CPD-Arg-NO pathway is involved in the regulation of PCa cell proliferation. It further highlights a role for PRL in the development and progression of PCa.
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Affiliation(s)
- Lynn N Thomas
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Jennifer Merrimen
- Department of Pathology, Dalhousie University, Halifax, NS, Canada
- Department of Urology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - David G Bell
- Department of Urology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Ricardo Rendon
- Department of Urology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Catherine K L Too
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
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Proteolytic Processing of Neuropeptides. ANALYSIS OF POST-TRANSLATIONAL MODIFICATIONS AND PROTEOLYSIS IN NEUROSCIENCE 2015. [DOI: 10.1007/7657_2015_87] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Wardman JH, Fricker LD. ProSAAS-derived peptides are differentially processed and sorted in mouse brain and AtT-20 cells. PLoS One 2014; 9:e104232. [PMID: 25148519 PMCID: PMC4141687 DOI: 10.1371/journal.pone.0104232] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 07/08/2014] [Indexed: 11/18/2022] Open
Abstract
ProSAAS is the precursor for some of the most abundant peptides found in mouse brain and other tissues, including peptides named SAAS, PEN, and LEN. Both SAAS and LEN are found in big and little forms due to differential processing. Initial processing of proSAAS is mediated by furin (and/or furin-like enzymes) and carboxypeptidase D, while the smaller forms are generated by secretory granule prohormone convertases and carboxypeptidase E. In mouse hypothalamus, PEN and big LEN colocalize with neuropeptide Y. In the present study, little LEN and SAAS were detected in mouse hypothalamus but not in cell bodies of neuropeptide Y-expressing neurons. PEN and big LEN show substantial colocalization in hypothalamus, but big LEN and little LEN do not. An antiserum to SAAS that detects both big and little forms of this peptide did not show substantial colocalization with PEN or big LEN. To further study this, the AtT-20 cells mouse pituitary corticotrophic cell line was transfected with rat proSAAS and the distribution of peptides examined. As found in mouse hypothalamus, only some of the proSAAS-derived peptides colocalized with each other in AtT-20 cells. The two sites within proSAAS that are known to be efficiently cleaved by furin were altered by site-directed mutagenesis to convert the P4 Arg into Lys; this change converts the sequences from furin consensus sites into prohormone convertase consensus sites. Upon expression of the mutated form of proSAAS in AtT-20 cells, there was significantly more colocalization of proSAAS-derived peptides PEN and SAAS. Taken together, these results indicate that proSAAS is initially cleaved in the Golgi or trans-Golgi network by furin and/or furin-like enzymes and the resulting fragments are sorted into distinct vesicles and further processed by additional enzymes into the mature peptides.
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Affiliation(s)
- Jonathan H. Wardman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Lloyd D. Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
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Husson SJ, Reumer A, Temmerman L, De Haes W, Schoofs L, Mertens I, Baggerman G. Worm peptidomics. EUPA OPEN PROTEOMICS 2014. [DOI: 10.1016/j.euprot.2014.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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17
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Thomas LN, Merrimen J, Bell DG, Rendon R, Goffin V, Too CKL. Carboxypeptidase-D is elevated in prostate cancer and its anti-apoptotic activity is abolished by combined androgen and prolactin receptor targeting. Prostate 2014; 74:732-42. [PMID: 24615730 DOI: 10.1002/pros.22793] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 01/28/2014] [Indexed: 11/08/2022]
Abstract
BACKGROUND Carboxypeptidase-D (CPD) cleaves C-terminal arginine for nitric oxide (NO) production. CPD and NO levels are upregulated by testosterone (T) and prolactin (PRL) to promote survival of prostate cancer (pCa) cells. This study evaluated CPD immunostaining and T/PRL regulation of CPD and NO levels in benign and malignant prostate tissues/cells to determine the role of CPD in pCa. METHODS Immunohistochemistry (IHC) and tissue microarrays (TMA) were used to determine CPD immunostaining in prostate specimens. QPCR and immunoblotting were used to quantify CPD mRNA/protein expression in prostate cells. NO production was measured using 4,5-diaminofluorescein diacetate assay. RESULTS CPD staining increased from 8.9 ± 3.8% (Mean ± SEM, n = 15) of benign epithelial cell area to 30.9 ± 2.9% (n = 30) of tumor cell area in one set of TMAs (P = 0.0008) and from 5.9 ± 0.9% (n = 45) of benign epithelial cell area to 18.8 ± 1.9% (n = 55) of tumor area in another (P < 0.0001). IHC of prostate tissues (≥50 mm(2)) confirmed increased CPD staining, from 13.1 ± 2.9% in benign (n = 16) to 29.5 ± 4.4% in pCa (n = 31, P = 0.0095). T and/or PRL increased CPD expression in several pCa but not benign cell lines. T and PRL acted synergistically to increase NO production, which was abolished only when receptor antagonists flutamide and Δ1-9-G129R-hPRL were used together. CONCLUSIONS CPD immunostaining and T/PRL-stimulated CPD expression were higher in pCa than benign tissues/cells. Elevated CPD increased NO production, which was abolished when both AR and PRLR were inhibited. Our study implicates a critical role for the T/PRL-stimulated CPD-Arg-NO pathway in pCa progression, and suggests that AR+PRLR inhibition is a more effective treatment for pCa.
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Affiliation(s)
- Lynn N Thomas
- Departments of Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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Sapio MR, Fricker LD. Carboxypeptidases in disease: insights from peptidomic studies. Proteomics Clin Appl 2014; 8:327-37. [PMID: 24470285 DOI: 10.1002/prca.201300090] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/10/2013] [Accepted: 10/30/2013] [Indexed: 12/19/2022]
Abstract
Carboxypeptidases (CPs) perform many diverse physiological functions by removing C-terminal amino acids from proteins and peptides. Some CPs function in the degradation of proteins in the digestive tract while other enzymes play biosynthetic roles in the formation of neuropeptides and peptide hormones. Another set of CPs modify tubulin by removing amino acids from the C-terminus and from polyglutamyl side chains, thereby altering the properties of microtubules. This review focuses on three CPs: carboxypeptidase E, carboxypeptidase A6, and cytosolic carboxypeptidase 1. Naturally occurring mutations in all three of these enzymes are associated with disease phenotypes, ranging from obesity to epilepsy to neurodegeneration. Peptidomics is a useful tool to investigate the relationship between these mutations and alterations in peptide levels. This technique has also been used to define the function and characteristics of CPs. Results from peptidomics studies have helped to elucidate the function of CPs and clarify the biological underpinnings of pathologies by identifying peptides altered in disease states. This review describes the use of peptidomic techniques to gain insights into the normal function of CPs and the molecular defects caused by mutations in the enzymes.
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Affiliation(s)
- Matthew R Sapio
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
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Koirala S, Thomas LN, Too CKL. Prolactin/Stat5 and androgen R1881 coactivate carboxypeptidase-D gene in breast cancer cells. Mol Endocrinol 2014; 28:331-43. [PMID: 24433040 DOI: 10.1210/me.2013-1202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Plasma membrane-bound carboxypeptidase-D (CPD) cleaves C-terminal arginine from extracellular substrates. In the cell, arginine is converted to nitric oxide (NO). We have reported that up-regulation of CPD mRNA/protein levels by 17β-estradiol and prolactin (PRL) in breast cancer cells, and by testosterone in prostate cancer cells, increased NO production and cell survival. The CPD promoter contains a consensus γ-interferon-activated sequence (GAS) and 3 putative androgen response elements (ARE.1, ARE.2, ARE.3) that could potentially bind PRL-activated transcription factor Stat5 (signal transducer and activator of transcription 5) and the liganded androgen receptor (AR), respectively. This study showed that synthetic androgen R1881 and PRL elevated CPD mRNA/protein levels in human MCF-7 and T47D breast cancer cells in a time-/dose-dependent manner. PRL/R1881-elevated CPD expression was blocked by actinomycin-D, and a CPD promoter construct containing these GAS and AREs was stimulated by PRL or R1881, indicating transcriptional regulation by both hormones. Luciferase reporter assays showed that GAS and the adjacent ARE.1 only were active. Mutation of GAS in the ΔGAS-CPD construct (ARE.1 intact) abolished CPD promoter activity in response to PRL and, surprisingly, to R1881 as well. ΔGAS-CPD promoter activity was restored by PRL+R1881 in combination, and enhanced by ectopic Stat5, but abolished by Stat5 gene knockdown. Chromatin immunoprecipitation analysis confirmed binding of activated Stat5 and liganded AR to GAS and ARE.1, respectively. Activated Stat5 also induced binding of unliganded AR to ARE.1, and liganded AR induced binding of unactivated Stat5 to GAS. In summary, PRL and R1881, acting through Stat5 and AR, act cooperatively to stimulate CPD gene transcription in breast cancer cells.
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Affiliation(s)
- Samir Koirala
- Department of Biochemistry & Molecular Biology (S.K., L.N.T., C.K.L.T.) and Department of Obstetrics & Gynaecology (C.K.L.T.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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Overexpression of CPE-ΔN predicts poor prognosis in colorectal cancer patients. Tumour Biol 2013; 34:3691-9. [PMID: 23852859 DOI: 10.1007/s13277-013-0952-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/17/2013] [Indexed: 10/26/2022] Open
Abstract
Carboxypeptidase E (CPE) is one of the most important carboxypeptidases involved in biosynthesis of numerous peptide hormones and neurotransmitters and has an important role in endocrine regulation. A splice variant of CPE (CPE-ΔN) has been detected and the mechanism of CPE-ΔN action in tumorigenesis has been studied in many different cancers. The aim of this study was to examine CPE-ΔN expression in human colorectal cancer (CRC) and to evaluate its possible use as a potential prognostic marker. Two hundred nineteen primary colorectal tumors and corresponding normal tissues were included in the study. We have analyzed CPE-ΔN isoform expression by qRT-PCR and Western blot in 219 CRC patients. Correlations between CPE-ΔN mRNA expression and clinicopathological variables were determined with chi-square tests. Survival probabilities were determined using Kaplan-Meier analysis, and univariate and multivariate analyses of the prognostic factors were performed with a Cox regression model. Our results show that CPE-ΔN is overexpressed in colorectal tumor tissue and that high CPE-ΔN mRNA expression is closely correlated with tumor differentiation, pT classification, pN classification, tumor recurrence, and lymph node metastasis (P = 0.042, 0.036, 0.031, 0.006, and 0.008, respectively). However, no correlation was observed between CPE-ΔN expression and age, gender, tumor localization, gross features, and the tumor size. In addition, patients with high CPE-ΔN expression had a significantly shorter survival (P < 0.001, logrank test). Tumor differentiation, gross feature, pT classification, pN classification, tumor recurrence, lymph node metastasis, and CPE-ΔN status were significantly associated with poor prognosis after performing a univariate Cox survival analysis. High CPE-ΔN expression was also identified as an independent prognostic factor using a multivariate analysis (P = 0.011). Based on these results, we can conclude that CPE-ΔN expression might be a potential prognostic marker for colorectal cancer patients.
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Abstract
Peptide hormones with a C-terminal amide regulate numerous physiological processes and are associated with many disease states. Consequently, the key enzymes involved in their production, peptidylglycine α-amidating monooxygenase and carboxypeptidase E, have been studied intensively. This review surveys what is known about the enzymes themselves and their cofactors, as well as their substrates and competitive and mechanism-based inhibitors.
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Cawley NX, Wetsel WC, Murthy SRK, Park JJ, Pacak K, Loh YP. New roles of carboxypeptidase E in endocrine and neural function and cancer. Endocr Rev 2012; 33:216-53. [PMID: 22402194 PMCID: PMC3365851 DOI: 10.1210/er.2011-1039] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 01/18/2012] [Indexed: 01/14/2023]
Abstract
Carboxypeptidase E (CPE) or carboxypeptidase H was first discovered in 1982 as an enkephalin-convertase that cleaved a C-terminal basic residue from enkephalin precursors to generate enkephalin. Since then, CPE has been shown to be a multifunctional protein that subserves many essential nonenzymatic roles in the endocrine and nervous systems. Here, we review the phylogeny, structure, and function of CPE in hormone and neuropeptide sorting and vesicle transport for secretion, alternative splicing of the CPE transcript, and single nucleotide polymorphisms in humans. With this and the analysis of mutant and knockout mice, the data collectively support important roles for CPE in the modulation of metabolic and glucose homeostasis, bone remodeling, obesity, fertility, neuroprotection, stress, sexual behavior, mood and emotional responses, learning, and memory. Recently, a splice variant form of CPE has been found to be an inducer of tumor growth and metastasis and a prognostic biomarker for metastasis in endocrine and nonendocrine tumors.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular Neurobiology, Program on Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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Thomas LN, Morehouse TJ, Too CKL. Testosterone and prolactin increase carboxypeptidase-D and nitric oxide levels to promote survival of prostate cancer cells. Prostate 2012; 72:450-60. [PMID: 21688280 DOI: 10.1002/pros.21446] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 05/31/2011] [Indexed: 11/06/2022]
Abstract
BACKGROUND Plasma-membrane carboxypeptidase-D (CPD) releases arginine from extracellular substrates. Arginine is converted intracellularly to nitric oxide (NO). This study determined the effects of testosterone (T) and prolactin (PRL) on CPD expression, and the role(s) of CPD in NO production and survival of prostate cancer (PCa) cells. METHODS LNCaP cells were treated with T and/or PRL. CPD expression was measured. Regulation by T (low doses) was determined using transfected cells overexpressing 5α-reductase type-1 (5αR1), which converts T to the more potent dihydrotestosterone. The effects of siRNAs targeting CPD (siCPDs) on NO production, cell viability, and apoptosis were determined using DAF2-DA, MTS, and Annexin-V assays. The effects of PRL/T on CPD/NO levels in PC-3, MDA-PCa-2b, and 22Rv1 cells were also evaluated. RESULTS In LNCaP cells, 10 nM T and 10 ng/ml PRL-upregulated CPD mRNA/protein levels. In pTRE-transfectants, 1 nM T-upregulated CPD mRNA levels by ∼2-fold over controls, whereas 0.1 nM T caused similar upregulation in pTRE-5αR1-transfectants. In LNCaP cells cultured in arginine-free medium, addition of furylacryloyl-Ala-Arg (FAR; CPD substrate) increased NO levels. NO production, with FAR, was enhanced by PRL and/or T. siCPDs decreased NO production and cell viability, but increased apoptosis. QPCR analysis showed T/PRL-upregulation of CPD in 22Rv1, MDA-PCa-2b, and PC-3 cells. NO production was doubled by T/PRL in 22Rv1 cells, tripled by T in MDA-PCa-2b cells, and marginally increased by PRL in MDA-PCa-2b and PC-3 cells. CONCLUSIONS T and PRL upregulate CPD and NO levels in PCa cells. CPD increases NO production to promote PCa cell survival.
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Affiliation(s)
- Lynn N Thomas
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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Berezniuk I, Vu HT, Lyons PJ, Sironi JJ, Xiao H, Burd B, Setou M, Angeletti RH, Ikegami K, Fricker LD. Cytosolic carboxypeptidase 1 is involved in processing α- and β-tubulin. J Biol Chem 2011; 287:6503-17. [PMID: 22170066 DOI: 10.1074/jbc.m111.309138] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Purkinje cell degeneration (pcd) mouse has a disruption in the gene encoding cytosolic carboxypeptidase 1 (CCP1). This study tested two proposed functions of CCP1: degradation of intracellular peptides and processing of tubulin. Overexpression (2-3-fold) or knockdown (80-90%) of CCP1 in human embryonic kidney 293T cells (HEK293T) did not affect the levels of most intracellular peptides but altered the levels of α-tubulin lacking two C-terminal amino acids (delta2-tubulin) ≥ 5-fold, suggesting that tubulin processing is the primary function of CCP1, not peptide degradation. Purified CCP1 produced delta2-tubulin from purified porcine brain α-tubulin or polymerized HEK293T microtubules. In addition, CCP1 removed Glu residues from the polyglutamyl side chains of porcine brain α- and β-tubulin and also generated a form of α-tubulin with two C-terminal Glu residues removed (delta3-tubulin). Consistent with this, pcd mouse brain showed hyperglutamylation of both α- and β-tubulin. The hyperglutamylation of α- and β-tubulin and subsequent death of Purkinje cells in pcd mice was counteracted by the knock-out of the gene encoding tubulin tyrosine ligase-like-1, indicating that this enzyme hyperglutamylates α- and β-tubulin. Taken together, these results demonstrate a role for CCP1 in the processing of Glu residues from β- as well as α-tubulin in vitro and in vivo.
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Affiliation(s)
- Iryna Berezniuk
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Lyons PJ, Fricker LD. Carboxypeptidase O is a glycosylphosphatidylinositol-anchored intestinal peptidase with acidic amino acid specificity. J Biol Chem 2011; 286:39023-32. [PMID: 21921028 DOI: 10.1074/jbc.m111.265819] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The first metallocarboxypeptidase (CP) was identified in pancreatic extracts more than 80 years ago and named carboxypeptidase A (CPA; now known as CPA1). Since that time, seven additional mammalian members of the CPA subfamily have been described, all of which are initially produced as proenzymes, are activated by endoproteases, and remove either C-terminal hydrophobic or basic amino acids from peptides. Here we describe the enzymatic and structural properties of carboxypeptidase O (CPO), a previously uncharacterized and unique member of the CPA subfamily. Whereas all other members of the CPA subfamily contain an N-terminal prodomain necessary for folding, bioinformatics and expression of both human and zebrafish CPO orthologs revealed that CPO does not require a prodomain. CPO was purified by affinity chromatography, and the purified enzyme was able to cleave proteins and synthetic peptides with greatest activity toward acidic C-terminal amino acids unlike other CPA-like enzymes. CPO displayed a neutral pH optimum and was inhibited by common metallocarboxypeptidase inhibitors as well as citrate. CPO was modified by attachment of a glycosylphosphatidylinositol membrane anchor to the C terminus of the protein. Immunocytochemistry of Madin-Darby canine kidney cells stably expressing CPO showed localization to vesicular membranes in subconfluent cells and to the plasma membrane in differentiated cells. CPO is highly expressed in intestinal epithelial cells in both zebrafish and human. These results suggest that CPO cleaves acidic amino acids from dietary proteins and peptides, thus complementing the actions of well known digestive carboxypeptidases CPA and CPB.
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Affiliation(s)
- Peter J Lyons
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Tanco S, Arolas JL, Guevara T, Lorenzo J, Avilés FX, Gomis-Rüth FX. Structure-function analysis of the short splicing variant carboxypeptidase encoded by Drosophila melanogaster silver. J Mol Biol 2010; 401:465-77. [PMID: 20600119 PMCID: PMC7089606 DOI: 10.1016/j.jmb.2010.06.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 06/16/2010] [Accepted: 06/17/2010] [Indexed: 11/30/2022]
Abstract
Drosophila melanogaster silver gene is the ortholog of the coding gene of mammalian carboxypeptidase D (CPD). The silver gene gives rise to eight different splicing variants of differing length that can contain up to three homologous repeats. Among the protein variants encoded, the short form 1B alias DmCPD1Bs (D. melanogaster CPD variant 1B short) is necessary and sufficient for viability of the fruit fly. It has one single repeat, it is active against standard peptide substrates, and it is localized to the secretory pathway. In this work, the enzyme was found as a monomer in solution and as a homodimer in the crystal structure, which features a protomer with an N-terminal 311-residue catalytic domain of α/β-hydrolase fold and a C-terminal 84-residue all-β transthyretin-like domain. Overall, DmCPD1Bs conforms to the structure of N/E-type funnelins/M14B metallopeptidases, but it has two unique structural elements potentially involved in regulation of its activity: (i) two contiguous surface cysteines that may become palmitoylated and target the enzyme to membranes, thus providing control through localization, and (ii) a surface hot spot targetable by peptidases that would provide a regulatory mechanism through proteolytic inactivation. Given that the fruit fly possesses orthologs of only two out of the five proteolytically competent N/E-type funnelins found in higher vertebrates, DmCPD1Bs may represent a functional analog of at least one of the missing mammalian CPs.
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Affiliation(s)
- Sebastián Tanco
- Departament de Bioquímica i Biologia Molecular, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
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Fernández D, Pallarès I, Vendrell J, Avilés FX. Progress in metallocarboxypeptidases and their small molecular weight inhibitors. Biochimie 2010; 92:1484-500. [PMID: 20466032 DOI: 10.1016/j.biochi.2010.05.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 05/04/2010] [Indexed: 01/11/2023]
Abstract
In what corresponds to a life span, metallocarboxypeptidases (MCPs) have jumped from being mere contaminants in animal pancreas powders (in depression year 1929) to be key players in cellular and molecular processes (in yet-another-depression years 2009-2010). MCPs are unique zinc-dependent enzymes that catalyze the breakdown of the amide bond at the C-terminus of peptide and protein substrates and participate in the recovery of dietary amino acids, tissue organogenesis, neurohormone and cytokine maturation and other important physiological processes. More than 26 genes code for MCPs in the human genome, many of them still waiting to be fully understood in terms of physiological function. A variety of MCPs have been linked to diseases in man: acute pancreatitis and pancreas cancer, type 2 diabetes, Alzheimer's Disease, various types of cancer, and fibrinolysis and inflammation. Many of these discoveries have been made possible thanks to recent advances, as exemplified by plasma carboxypeptidases N and B, known for fifty and twenty years, respectively, which have had their structures released only very recently. Plasma carboxypeptidase B is a biological target for therapy because of its involvement in the coagulation/fibrinolysis processes. Besides, the widespread use of carboxypeptidase A as a benchmark metalloprotease since the early days of Biochemistry has allowed the identification and design of an increasingly vast repertory of small molecular weight inhibitors. With these two examples we wish to emphasize that MCPs have become part of the drug discovery portfolio of pharmaceutical companies and academic research laboratories. This paper will review key developments in the discovery and design of MCP small molecular weight inhibitors, with an emphasis on the discovery of chemically diverse entities. Although encouraging advances have been achieved in the last few years, the specificity and oral bioavailability of the new chemotherapeutic agents seem to pose a challenge to medicinal chemists.
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Affiliation(s)
- Daniel Fernández
- Departament de Bioquímica i Biologia Molecular, Facultat de Biociències and Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
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Singh U, Rizvi F, Yu Y, Shi W, Orth A, Karimi M, Ekström TJ, Plagge A, Kelsey G, Fundele R. Characterization of a novel obesity phenotype caused by interspecific hybridization. Arch Physiol Biochem 2008; 114:301-30. [PMID: 19085233 DOI: 10.1080/13813450802542495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
UNLABELLED Interspecific hybridization in mammals causes hybrid dysgenesis effects, such as sterility and abnormal placentation. Here, we describe a novel obesity syndrome caused by interspecific hybridization in the genus Mus and show that this obesity, appearing sporadically in F1 littermates derived from inbred strains, has an epigenetic basis. Mus hybrids from various strains of M. musculus and M. spretus were generated and the sporadic obese phenotype was confirmed through assessment of physiological and biochemical parameters in littermates. To understand the underlying mechanisms, large-scale and candidate gene expression assays, global DNA methylation assays and allelic expression analysis were performed. Studies showed that obese hybrids are similar to other known models of obesity. While increased axial growth indicated a defect in POMC pathway, comparison of global gene expression patterns in brain of obese F1 and obese Pomc mutant mice showed little similarity. In F1 obese mice many genes involved in the maintenance of epigenetic states, as well as several imprinted genes, were differentially expressed. Global DNA methylation analysis in brain showed that increased methylation levels were associated with obesity. The imprinted gene Gnasxl, known to be important in lipid homeostasis, was found over expressed in the obese hybrids. Allelic expression and methylation analysis of Gnasxl showed that alterations of epigenetic marks underlying F1 obesity are probably many and multi-factorial. CONCLUSIONS This model of obesity, which is both spontaneous and epigenetic, may be a useful tool to address the epigenetic aspects of clinical obesity.
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Affiliation(s)
- Umashankar Singh
- Department of Development and Genetics, Evolutionary Biology Center, Uppsala University, Uppsala, Sweden
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Abdelmagid SA, Too CKL. Prolactin and estrogen up-regulate carboxypeptidase-d to promote nitric oxide production and survival of mcf-7 breast cancer cells. Endocrinology 2008; 149:4821-8. [PMID: 18535109 DOI: 10.1210/en.2008-0145] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Carboxypeptidase-D (CPD) and carboxypeptidase-M (CPM) release C-terminal arginine (Arg) from polypeptides, and both are present in the plasma membrane. Cell-surface CPD increases intracellular Arg, which is converted to nitric oxide (NO). We have reported that prolactin (PRL) regulated CPD mRNA levels in MCF-7 breast cancer cells. This study examined PRL/17beta-estradiol (E2) regulation of CPD/CPM expression, and the role of CPD in NO production for survival of MCF-7 cells. We showed that PRL or E2 up-regulated CPD mRNA and protein expression. PRL/E2 increased CPD mRNA levels by 3- to 5-fold but had no effect on CPM. In Arg-free DMEM, exogenous L-Arg or substrate furylacryloyl-Ala-Arg (Fa-Ala-Arg) increased NO levels and cell survival, measured using 4,5-diaminofluorescein diacetate and the MTS assay, respectively. In the presence of Fa-Ala-Arg, NO production was enhanced by PRL and/or E2 but inhibited by CPD/CPM-specific inhibitor, 2-mercaptomethyl-3-guanidinoethylthio-propanoic acid (MGTA). MGTA also decreased MCF-7 cell survival. In Arg-free medium, annexin-V staining showed that apoptotic MCF-7 cells (approximately 60%) were rescued by Fa-Ala-Arg (25%) or diethylamine/NO (10%). Finally, CPD or CPM gene expression was knocked down with small interfering (si) CPD or siCPM, respectively, with nontargeting siNT as controls. In Arg-free DMEM, the stimulatory effect of Fa-Ala-Arg on NO production was inhibited by siCPD only, showing that CPD depletion inhibited Fa-Ala-Arg cleavage. Furthermore, more than 60% of siCPD-transfectants were apoptotic, and L-Arg, not Fa-Ala-Arg, significantly decreased apoptosis to 32% (P<or=0.05). Thus, CPD gene knockdown did not affect L-Arg uptake, which protected cells from apoptosis. In summary, PRL/E2-induced cell-surface CPD released Arg from extracellular substrates, increased intracellular NO, promoted survival and inhibited apoptosis of MCF-7 cells.
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Affiliation(s)
- Salma A Abdelmagid
- Department of Biochemistry and Molecular Biology, Sir Charles Tupper Medical Building, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5
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Abstract
Neuropeptidomics is the analysis of the neuropeptides present in a tissue extract. Most neuropeptidomic studies use mass spectrometry to detect and identify the peptides, which provides information on the precise posttranslationally modified form of each peptide. Quantitative peptidomics uses isotopic labels to compare the levels of peptides in extracts from two different samples. This technique is ideal for examining neuropeptide levels in a variety of systems and is especially suited for studies of mice lacking peptide-processing enzymes. This review is focused on the neuropeptidomics technique and its application to the analysis of mice with a mutation that inactivates carboxypeptidase E, a critical enzyme in the biosynthesis of many neuroendocrine peptides. Mice without carboxypeptidase E activity are overweight, and a key question is the identification of the peptide or peptides responsible. The quantitative peptidomics approach has provided some insights toward the answer to this question.
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Affiliation(s)
- Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
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Husson SJ, Janssen T, Baggerman G, Bogert B, Kahn-Kirby AH, Ashrafi K, Schoofs L. Impaired processing of FLP and NLP peptides in carboxypeptidase E (EGL-21)-deficient Caenorhabditis elegans as analyzed by mass spectrometry. J Neurochem 2007; 102:246-60. [PMID: 17564681 DOI: 10.1111/j.1471-4159.2007.04474.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biologically active peptides are synthesized from inactive pre-proproteins or peptide precursors by the sequential actions of processing enzymes. Proprotein convertases cleave the precursor at pairs of basic amino acids, which are then removed from the carboxyl terminus of the generated fragments by a specific carboxypeptidase. Caenorhabditis elegans strains lacking proprotein convertase EGL-3 display a severely impaired neuropeptide profile (Husson et al. 2006, J. Neurochem.98, 1999-2012). In the present study, we examined the role of the C. elegans carboxypeptidase E orthologue EGL-21 in the processing of peptide precursors. More than 100 carboxy-terminally extended neuropeptides were detected in egl-21 mutant strains. These findings suggest that EGL-21 is a major carboxypeptidase involved in the processing of FMRFamide-like peptide (FLP) precursors and neuropeptide-like protein (NLP) precursors. The impaired peptide profile of egl-3 and egl-21 mutants is reflected in some similar phenotypes. They both share a severe widening of the intestinal lumen, locomotion defects, and retention of embryos. In addition, egl-3 animals have decreased intestinal fat content. Taken together, these results suggest that EGL-3 and EGL-21 are key enzymes for the proper processing of neuropeptides that control egg-laying, locomotion, fat storage and the nutritional status.
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Affiliation(s)
- Steven J Husson
- Functional Genomics and Proteomics Unit, Department of Biology, Katholieke Universiteit Leuven, Leuven, Belgium.
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Hoff NP, Degrandi D, Hengge U, Pfeffer K, Wurthner JU. Carboxypeptidase D: A Novel TGF-β Target Gene Dysregulated in Patients with Lupus Erythematosus. J Clin Immunol 2007; 27:568-79. [PMID: 17641957 DOI: 10.1007/s10875-007-9118-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Accepted: 06/25/2007] [Indexed: 10/23/2022]
Abstract
Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine that mainly acts as an inhibitor of immune functions. A lack of functional TGF-beta leads to autoimmune disease in animal models and dysregulated TGF-beta signaling is implicated in human autoimmune diseases. To define target genes that play a part in the inhibitory role of TGF-beta in the immune system, we have identified genes stimulated by TGF-beta in macrophages by gene-chip analysis. One of the TGF-beta regulated genes is carboxypeptidase D (CpD), a 180-kDa type I membrane protein. We have demonstrated that CpD is regulated by TGF-beta in various cell types of both, murine and human origin and, interestingly, is significantly downregulated in CD14 positive cells isolated from patients with lupus erythematosus (LE). Moreover, we show that downregulation of CpD leads to downmodulation of TGF-beta itself, suggesting a role for CpD in a positive feedback loop, providing further evidence for a role of this enzyme in LE. To our knowledge, this is the first report that demonstrates carboxypeptidase D as a TGF-beta target gene that is implicated in the pathogenesis of LE.
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Affiliation(s)
- Norman-Philipp Hoff
- Institute for Medical Microbiology, University of Duesseldorf, 40225, Duesseldorf, Germany.
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Singh U, Yu Y, Kalinina E, Konno T, Sun T, Ohta H, Wakayama T, Soares MJ, Hemberger M, Fundele RH. Carboxypeptidase E in the mouse placenta. Differentiation 2007; 74:648-60. [PMID: 17177860 DOI: 10.1111/j.1432-0436.2006.00093.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Carboxypeptidase E (CPE) has important functions in processing of endocrine pro-peptides, such as pro-insulin, pro-opiomelanocortin, or pro-gonadotropin-releasing hormone, as evidenced by the hyper-pro-insulinemia, obesity, and sterility of Cpe mutant mice. Down-regulation of Cpe in enlarged placentas of interspecific hybrid (interspecies hybrid placental dysplasia (IHPD)) and cloned mice suggested that reduced CPE enzyme and receptor activity could underlie abnormal placental phenotypes. In this study, we have explored the role of Cpe in murine placentation by determining its expression at various stages of gestation, and by phenotypic analysis of Cpe mutant placentas. Our results show that Cpe and Carboxypeptidase D (Cpd), another carboxypeptidase with a very similar function, are strictly co-localized in the mouse placenta from late mid-gestation to term. We also show that absence of CPE causes a sporadic but striking placental phenotype characterized by an increase in giant and glycogen cell numbers and giant cell hypertrophy. Microarray-based transcriptional profiling of Cpe mutant placentas identified only a very small number of genes with altered expression, including Dtprp, which belongs to the prolactin gene family. Concordant deregulation of Cpe and Cpd in abnormal placentas of interspecies hybrids before the onset of IHPD phenotype and recapitulation of some phenotypes of IHPD hyperplastic placentas in Cpe mutant placentas suggests that these two genes are causally involved in IHPD and may function as speciation genes in the genus Mus.
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Affiliation(s)
- Umashankar Singh
- Department of Development and Genetics, Evolutionary Biology Center, Uppsala University, 75236 Uppsala, Sweden
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Deiteren K, Surpateanu G, Gilany K, Willemse JL, Hendriks DF, Augustyns K, Laroche Y, Scharpé S, Lambeir AM. The role of the S1 binding site of carboxypeptidase M in substrate specificity and turn-over. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1774:267-77. [PMID: 17208058 DOI: 10.1016/j.bbapap.2006.11.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 11/29/2006] [Accepted: 11/30/2006] [Indexed: 10/23/2022]
Abstract
The influence of the P1 amino acid on the substrate selectivity, the catalytic parameters K(m) and k(cat), of carboxypeptidase M (CPM) (E.C. 3.4.17.12) was systematically studied using a series of benzoyl-Xaa-Arg substrates. CPM had the highest catalytic efficiency (k(cat)/K(m)) for substrates with Met, Ala and aromatic amino acids in the penultimate position and the lowest with amino acids with branched side-chains. Substrates with Pro in P1 were not cleaved in similar conditions. The P1 substrate preference of CPM differed from that of two other members of the carboxypeptidase family, CPN (CPN/CPE subfamily) and CPB (CPA/CPB subfamily). Aromatic P1 residues discriminated most between CPM and CPN. The type of P2 residue also influenced the k(cat) and K(m) of CPM. Extending the substrate up to P7 had little effect on the catalytic parameters. The substrates were modelled in the active site of CPM. The results indicate that P1-S1 interactions play a role in substrate binding and turn-over.
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Affiliation(s)
- Kathleen Deiteren
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
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Sidyelyeva G, Baker NE, Fricker LD. Characterization of the molecular basis of the Drosophila mutations in carboxypeptidase D. Effect on enzyme activity and expression. J Biol Chem 2006; 281:13844-13852. [PMID: 16556608 DOI: 10.1074/jbc.m513499200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carboxypeptidase D (CPD) functions in the processing of proteins and peptides in the secretory pathway. Drosophila CPD is encoded by the silver gene (svr), which is differentially spliced to produce long transmembrane protein forms with three metallocarboxypeptidase (CP)-like domains and short soluble forms with a single CP domain. Many svr mutants have been reported, but the precise molecular defects have not been previously determined. In the present study, three mutant lines were characterized. svr (PG33) mutants do not survive past the early larval stage. These mutants have a P-element insertion within exon 1B upstream of the initiation ATG, which greatly reduces mRNA levels of all forms of CPD. Both svr (1) and svr (poi) mutants are viable, with a silvery body color and pointed wings. The wing shape is generally similar between these two mutants, although svr (poi) mutants have smaller wings. The svr (1) gene has a three-nucleotide deletion in exon 6, removing a leucine in a region of the protein predicted to function as a folding domain for the second CP-like domain. svr (poi) has a 1072-bp duplication of the gene that introduces a stop codon into the open reading frame, causing the truncation of the protein in the middle of the second CP-like domain. Both deletions eliminate enzyme activity of the second CP-like domain and appear to cause the misfolding of the protein. This greatly reduces the levels of the long forms of CPD protein but do not affect the levels of the short forms. Taken together, these findings suggest that lethal and viable svr alleles differ in which protein forms are affected. Flies that retain the short form are viable, whereas flies that are missing all forms of CPD do not survive past the early larval stages.
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Affiliation(s)
- Galyna Sidyelyeva
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Nicholas E Baker
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461.
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Lim J, Berezniuk I, Che FY, Parikh R, Biswas R, Pan H, Fricker LD. Altered neuropeptide processing in prefrontal cortex of Cpefat/fat mice: implications for neuropeptide discovery. J Neurochem 2006; 96:1169-81. [PMID: 16417576 DOI: 10.1111/j.1471-4159.2005.03614.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biosynthesis of most neuropeptides and peptide hormones requires a carboxypeptidase such as carboxypeptidase E, which is inactive in Cpe(fat/fat) mice due to a naturally occurring point mutation. To assess the role of carboxypeptidase E in the processing of peptides in the prefrontal cortex, we used a quantitative peptidomics approach to examine the relative levels of peptides in Cpe(fat/fat) versus wild-type mice. Peptides representing internal fragments of prohormones and other secretory pathway proteins were decreased two- to 10-fold in the Cpe(fat/fat) mouse prefrontal cortex compared with wild-type tissue. Degradation fragments of cytosolic proteins showed no major differences between Cpe(fat/fat) and wild-type mice. Based on this observation, a search strategy for neuropeptides was performed by screening for peptides that decreased in the Cpe(fat/fat) mouse. Altogether, 32 peptides were identified, of which seven have not been previously reported. The novel peptides include fragments of VGF, procholecystokinin and prohormone convertase 2. Interestingly, several of the peptides do not fit with the consensus sites for prohormone convertase 1 and 2, raising the possibility that another endopeptidase is involved with their biosynthesis. Taken together, these findings support the proposal that carboxypeptidase E is the major, but not the only, peptide-processing carboxypeptidase and also demonstrate the feasibility of searching for novel peptides based on their decrease in Cpe(fat/fat) mice.
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Affiliation(s)
- Jihyeon Lim
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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O'Malley P, Sangster S, Abdelmagid S, Bearne S, Too C. Characterization of a novel, cytokine-inducible carboxypeptidase D isoform in haematopoietic tumour cells. Biochem J 2006; 390:665-73. [PMID: 15918796 PMCID: PMC1199659 DOI: 10.1042/bj20050025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
CPD-N is a cytokine-inducible CPD (carboxypeptidase-D) isoform identified in rat Nb2 T-lymphoma cells. The prototypic CPD (180 kDa) has three CP domains, whereas CPD-N (160 kDa) has an incomplete N-terminal domain I but intact domains II and III. CPD processes polypeptides in the TGN (trans-Golgi network) but the Nb2 CPD-N is nuclear. The present study identified a cryptic exon 1', downstream of exon 1 of the rat CPD gene, as an alternative transcription start site that encodes the N-terminus of CPD-N. Western-blot analysis showed exclusive synthesis of the 160 kDa CPD-N in rat Nb2 and Nb2-Sp lymphoma cells. Several haematopoietic cell lines including human K562 myeloma, Jurkat T-lymphoma and murine CTLL-2 cytotoxic T-cells express a 160 kDa CPD-immunoreactive protein, whereas mEL4 T-lymphoma cells express the 180 kDa CPD. The CPD-immunoreactive protein in hK562 cells is also nuclear and cytokine-inducible. In contrast, MCF-7 breast cancer cells express only the 180 kDa CPD, which is mainly in the TGN. CPD/CPD-N assays using substrate dansyl-L-alanyl-L-arginine show approx. 98% of CPD-N activity in the Nb2 nucleus, whereas MCF-7 CPD activity is enriched in the post-nuclear 10000 g pellet. The K(m) for CPD-N and CPD are 132+/-30 and 63+/-9 microM respectively. Specific activity/K(m) ratios show that dansyl-L-alanyl-L-arginine is a better substrate for CPD-N than for CPD. CPD-N has an optimal pH of 5.6 (due to domain II), whereas CPD has activity peaks at pH 5.6 (domain II) and pH 6.5-7.0 (domain I). CPD and CPD-N are inhibited non-competitively by zinc chelator 1,10-phenanthroline and competitively by peptidomimetic inhibitor DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid. The Nb2 CPD-N co-immunoprecipitated with phosphatase PP2A (protein phosphatase 2A) and alpha4 phosphoprotein. In summary, a cytokine-inducible CPD-N is selectively expressed in several haematopoietic tumour cells. Nuclear CPD-N is enzymatically active and interacts with known partners of CPD.
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Affiliation(s)
- Padraic G. P. O'Malley
- *Department of Biochemistry and Molecular Biology, Sir Charles Tupper Medical Building, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
| | - Shirley M. Sangster
- *Department of Biochemistry and Molecular Biology, Sir Charles Tupper Medical Building, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
| | - Salma A. Abdelmagid
- *Department of Biochemistry and Molecular Biology, Sir Charles Tupper Medical Building, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
| | - Stephen L. Bearne
- *Department of Biochemistry and Molecular Biology, Sir Charles Tupper Medical Building, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
| | - Catherine K. L. Too
- *Department of Biochemistry and Molecular Biology, Sir Charles Tupper Medical Building, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
- †Department of Obstetrics and Gynecology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5
- To whom correspondence should be addressed (email )
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Kalinina E, Fontenele-Neto JD, Fricker LD. Drosophila S2 cells produce multiple forms of carboxypeptidase D with different intracellular distributions. J Cell Biochem 2006; 99:770-83. [PMID: 16676361 DOI: 10.1002/jcb.20972] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Carboxypeptidase D (CPD) functions in the processing of proteins that transit the secretory pathway, and is present in all vertebrates examined as well as Drosophila. Several forms of CPD mRNA were previously found in Drosophila that resulted from differential splicing of the gene. In the present study, Northern blot, reverse transcriptase PCR, and Western blot analysis showed that each splice variant occurs in a single cell type, the Drosophila-derived Schneider 2 (S2) cell line. The short forms containing a single carboxypeptidase domain were secreted from the S2 cells while the long forms containing three carboxypeptidase domains, a transmembrane domain, and one of two different cytosolic tails were retained in the cell. To investigate the role of the two different C-terminal tail sequences (tail-1 and tail-2) that result from the differential splicing within exon 8, constructs containing a reporter protein (albumin) attached to the transmembrane domain and tail-1 or tail-2 of CPD were expressed in S2 cells and a mouse pituitary cell line (AtT20 cells). Immunofluorescence analysis revealed different intracellular distributions of the two constructs, with the tail-2 construct showing considerable overlap with a Golgi marker. The two C-terminal tail sequences also resulted in different internalization efficiencies from the cell surface in both cell lines. Interestingly, the distribution and routing of the tail-2 form of Drosophila CPD in the AtT20 cells are similar to the previously characterized endogenous mouse CPD protein, indicating that the elements for this trafficking have been conserved between Drosophila and mammals.
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Affiliation(s)
- Elena Kalinina
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Abstract
Neuropeptides serve many important roles in communication between cells and are an attractive target for drug discovery. Neuropeptides are produced from precursor proteins by selective cleavages at specific sites, and are then broken down by further cleavages. In general, the biosynthetic cleavages occur within the cell and the degradative cleavages occur postsecretion, although there are exceptions where intracellular processing leads to inactivation, or extracellular processing leads to activation of a particular neuropeptide. A relatively small number of peptidases are responsible for processing the majority of neuropeptides, both inside and outside of the cell. Thus, inhibition of any one enzyme will lead to a broad effect on several different neuropeptides and this makes it unlikely that such inhibitors would be useful therapeutics. However, studies with mutant animals that lack functional peptide-processing enzymes have facilitated the discovery of novel neuropeptides, many of which may be appropriate targets for therapeutics.
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Affiliation(s)
- Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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Che FY, Yuan Q, Kalinina E, Fricker LD. Peptidomics of Cpe fat/fat mouse hypothalamus: effect of food deprivation and exercise on peptide levels. J Biol Chem 2004; 280:4451-61. [PMID: 15572367 DOI: 10.1074/jbc.m411178200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carboxypeptidase E is a major enzyme in the biosynthesis of numerous neuroendocrine peptides. Previously, we developed a technique for the isolation of neuropeptide-processing intermediates from mice that lack carboxypeptidase E activity (Cpe fat/fat mice) due to a naturally occurring point mutation. In the present study, we used a differential labeling procedure with stable isotopic tags and mass spectrometry to quantitate the relative changes in a number of hypothalamic peptides in Cpe fat/fat mice in two different paradigms that each cause an approximately 10% decrease in body mass. One paradigm involved a 2-day fast under normal sedentary conditions (i.e. standard mouse cages); the other involved giving mice access to an exercise wheel for 4 weeks with free access to food. Approximately 50 peptides were detected in both studies, and over 80 peptides were detected in at least one of the two studies. Twenty-eight peptides were increased >50% by food deprivation, and some of these were increased by 2- to 3-fold. In contrast, only three peptides were increased >50% in the group with exercise wheels, and many peptides showed a slight 15-30% decrease upon exercise. Approximately one-half of the peptides detected in both studies were identified by tandem mass spectrometry. Peptides found to be elevated by food deprivation but not exercise included a number of fragments of proenkephalin, prothyrotropin-releasing hormone, secretogranin II, chromogranin B, and pro-SAAS. Taken together, the differential regulation of these peptides in the two paradigms suggests that the regulation is not due to the lower body weight but to the manner in which the paradigms achieved this lower body weight.
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Affiliation(s)
- Fa-Yun Che
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Hadkar V, Sangsree S, Vogel SM, Brovkovych V, Skidgel RA. Carboxypeptidase-mediated enhancement of nitric oxide production in rat lungs and microvascular endothelial cells. Am J Physiol Lung Cell Mol Physiol 2004; 287:L35-45. [PMID: 14977629 DOI: 10.1152/ajplung.00346.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Membrane-bound regulatory carboxypeptidases cleave only COOH-terminal basic residues from peptides and proteins. To investigate whether carboxypeptidase-generated arginine can increase nitric oxide (NO) synthesis we perfused rat lungs from animals challenged with LPS or used rat lung microvascular endothelial cells (RLMVEC) stimulated with LPS and IFN-γ, conditions that induced inducible NO synthase (iNOS) expression. Addition of carboxypeptidase substrate furylacryloyl-Ala-Arg (Fa-A-R) or Arg to the lung perfusate increased NO production two- to threefold. The carboxypeptidase inhibitor 2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MGTA) blocked the effect of Fa-A-R but not free Arg. Lysine, an Arg transport inhibitor, blocked the increase in NO stimulated by Fa-A-R. HPLC analysis showed that Fa-A-R hydrolysis was blocked by MGTA but not lysine. In cytokine-treated RLMVEC, Fa-A-R also stimulated NO production inhibited by MGTA or lysine. Membrane fractions from rat lungs or RLMVEC contained carboxypeptidase M-like activity at neutral pH that increased twofold in RLMVEC treated with LPS + IFN-γ. The kinetics of NO production in RLMVEC was measured with a porphyrinic microsensor. Addition of 1 mM Arg or Fa-A-R to cells preincubated in Arg-free medium resulted in a slowly rising, prolonged (>20 min) NO output. NO production stimulated by Fa-A-R was blocked by MGTA or iNOS inhibitor 1400W. HPLC analysis of Fa-A-R hydrolysis revealed only 3.7 μM Arg was released over 20 min. Thus NO production in RLMVEC is stimulated more efficiently by Arg released from carboxypeptidase substrates than free Arg. These studies reveal a novel mechanism by which the Arg supply for NO production in inflammatory conditions may be maintained.
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Affiliation(s)
- Vaishali Hadkar
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, 60612, USA
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Abstract
The recent characterization of diverse vertebrate genomes has revealed the importance of gene duplication in vertebrate evolution. Evidence suggests that a genome duplication event occurred on the lineage leading to teleost fish-species that are often used to understand human biology. The existence of a genome duplication event complicates the use of fish as a model for human diseases as there are often two fish homologues for a single copy human gene. Often the second homologue has not been recognized. Our searches of the near complete zebrafish and fugu fish genomes indicate that both species have two insulin genes. Phylogenetic analysis indicates that the two genes are likely the product of the fish-specific genome duplication. The maintenance of two insulin genes within the fish suggests that the two genes have different functions. Thus the well-characterized insulin genes in some fish species may not be complete homologues of the human insulin gene.
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Affiliation(s)
- David M Irwin
- Department of Laboratory Medicine and Pathobiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ont., Canada M5G 1L5.
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Czyzyk TA, Morgan DJ, Peng B, Zhang J, Karantzas A, Arai M, Pintar JE. Targeted mutagenesis of processing enzymes and regulators: Implications for development and physiology. J Neurosci Res 2003; 74:446-55. [PMID: 14598321 DOI: 10.1002/jnr.10792] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Traci A Czyzyk
- Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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Fayad T, Lévesque V, Sirois J, Silversides DW, Lussier JG. Gene expression profiling of differentially expressed genes in granulosa cells of bovine dominant follicles using suppression subtractive hybridization. Biol Reprod 2003; 70:523-33. [PMID: 14568916 DOI: 10.1095/biolreprod.103.021709] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Development of antral follicles beyond 3 to 4 mm in cattle appears as a wave pattern that occurs two to three times during the estrous cycle. Each wave presents a cyclic recruitment of multiple follicles at the 3- to 4-mm stage, followed by the selection of a single follicle that becomes the dominant follicle (DF). The molecular determinants involved in the follicular dominance process remain poorly understood. The objective of the current study was to compare gene expression in granulosa cells (GCs) between growing dominant follicles from Day 5 of the estrous cycle and nonselected small follicles (<or=4 mm) using the suppression subtractive hybridization (SSH) approach to identify candidate genes differentially expressed in GCs of the DF. Small follicle cDNAs were subtracted from DF cDNAs (DF-SF) and used to establish a DF GC-subtracted cDNA library. A total of 42 nonredundant cDNAs were identified. Detection of previously identified genes such as CX43, CYP19, INHBA, and SERPINE2 supported the validity of our experimental model and the use of SSH as the method of analysis. For selected genes such as ApoER2, CPD, CSPG2, 14-3-3 epsilon, NR5A2/SF2, RGN/SMP30, and SERPINE2, gene expression profiles were compared by virtual Northern blot or reverse transcriptase-polymerase chain reaction, and results confirmed an increase or induction of their mRNA in GCs of dominant follicles compared with that of small follicles. We conclude that we have identified novel genes (known and unknown) that are up-regulated in bovine GCs that may affect follicular growth, dominance, or both.
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Affiliation(s)
- Tania Fayad
- Centre de recherche en reproduction animale, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, J2S 7C6, Canada
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Abstract
Neuropeptides are generally produced from precursor proteins by selective cleavage at specific sites, usually involving basic amino acids. Enzymes such as the prohormone convertases and carboxypeptidase E are highly specific for these basic amino acid-containing sites. In addition to this "traditional" pathway, several neuropeptides are known to be cleaved at non-basic sites, and the enzymes responsible for these cleavages have not been conclusively identified. In a recent search for novel members of the metallocarboxypeptidase family, we found three human genes. One of these, named "CPA-5," has a specificity for C-terminal hydrophobic amino acids and mRNA expression in brain, pituitary, and testis. To test whether CPA-5 protein has a distribution pattern in pituitary that is consistent with a role for this enzyme in the non-basic processing of proopiomelanocortin-derived peptides such as beta-endorphin and adrenocorticotropin, we examined the distribution of CPA-5 using immunocytochemistry. In the pituitary, CPA-5 is detected in the neurointermediate lobe and in scattered cells in the anterior lobe. In the AtT-20 corticotroph cell line, CPA-5 has a perinuclear distribution. Taken together, these results are consistent with a role for CPA-5 in the intracellular processing of proopiomelanocortin-derived peptides at non-basic sites.
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Affiliation(s)
- Suwen Wei
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Sangsree S, Brovkovych V, Minshall RD, Skidgel RA. Kininase I-type carboxypeptidases enhance nitric oxide production in endothelial cells by generating bradykinin B1 receptor agonists. Am J Physiol Heart Circ Physiol 2003; 284:H1959-68. [PMID: 12623793 DOI: 10.1152/ajpheart.00036.2003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Kininase I-type carboxypeptidases convert native kinin agonists for B(2) receptors into B(1) receptor agonists by specifically removing the COOH-terminal Arg residue. The membrane localization of carboxypeptidase M (CPM) and carboxypeptidase D (CPD) make them ideally situated to regulate kinin activity. Nitric oxide (NO) release from human lung microvascular endothelial cells (HLMVEC) was measured directly in real time with a porphyrinic microsensor. Bradykinin (1-100 nM) elicited a transient (5 min) peak of generation of NO that was blocked by the B(2) antagonist HOE 140, whereas B(1) agonist des-Arg(10)-kallidin caused a small linear increase in NO over 20 min. Treatment of HLMVEC with 5 ng/ml interleukin-1beta and 200 U/ml interferon-gamma for 16 h upregulated B(1) receptors as shown by an approximately fourfold increase in prolonged (>20 min) output of NO in response to des-Arg(10)-kallidin, which was blocked by the B(1) antagonist des-Arg(10)-Leu(9)-kallidin. B(2) receptor agonists bradykinin or kallidin also generated prolonged NO production in treated HLMVEC, which was significantly reduced by either a B(1) antagonist or carboxypeptidase inhibitor, and completely abolished with a combination of B(1) and B(2) receptor antagonists. Furthermore, CPM and CPD activities were increased about twofold in membrane fractions of HLMVEC treated with interleukin-1beta and interferon-gamma compared with control cells. Immunostaining localized CPD primarily in a perinuclear/Golgi region, whereas CPM was on the cell membrane. These data show that cellular kininase I-type carboxypeptidases can enhance kinin signaling and NO production by converting B(2) agonists to B(1) agonists, especially in inflammatory conditions.
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Affiliation(s)
- Sakonwun Sangsree
- Department of Pharmacology, University of Illinois College of Medicine, Chicago 60612, USA
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Kalinina EV, Fricker LD. Palmitoylation of carboxypeptidase D. Implications for intracellular trafficking. J Biol Chem 2003; 278:9244-9. [PMID: 12643288 DOI: 10.1074/jbc.m209379200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Covalent lipid modifications mediate protein-membrane and protein-protein interactions and are often essential for function. The purposes of this study were to examine the Cys residues of the transmembrane domain of metallocarboxypeptidase D (CPD) that could be a target for palmitoylation and to clarify the function of this modification. CPD is an integral membrane protein that cycles between the trans Golgi network and the plasma membrane. We constructed AtT-20 cells stably expressing various constructs carrying a reporter protein (albumin) fused to a transmembrane domain and the CPD cytoplasmic tail. Some of the constructs contained the three Cys residues present in the CPD transmembrane region, while other constructs contained Ala in place of the Cys. Constructs carrying Cys residues were palmitoylated, while those constructs lacking the Cys residues were not. Because palmitoylation of several proteins affects their association with cholesterol and sphingolipid-rich membrane domains or caveolae, we tested endogenous CPD and several of the reporter constructs for resistance to extraction with Triton X-100. A construct containing the Cys residues of the CPD transmembrane domain was soluble in Triton X-100 as was endogenous palmitoylated CPD, indicating that palmitoylation does not target CPD to detergent-resistant membrane rafts. Interestingly, constructs of CPD that lack palmitoylation sites have an increased half-life, a slightly more diffuse steady-state localization, and a slower rate of exit from the Golgi as compared with constructs containing palmitoylation sites. Thus, the covalent attachment of palmitic acid to the Cys residues of CPD has a functional significance in the trafficking of the protein.
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Affiliation(s)
- Elena V Kalinina
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Affiliation(s)
- William C Wetsel
- Departments of Psychiatry and Behavioral Sciences, Medicine (Endocrinology), and Cell Biology, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, NC 27710, USA.
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Abstract
Metallocarboxypeptidase D (CPD), is a 180-kDa protein that contains three carboxypeptidase-like domains, a transmembrane domain, and a cytosolic tail and which functions in the processing of proteins that transit the secretory pathway. An initial report on the Drosophila melanogaster silver gene indicated a CPD-like protein with only two and a half carboxypeptidase-like domains with no transmembrane region (Settle, S. H., Jr., Green, M. M., and Burtis, K. C. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 9470-9474). A variety of bioinformatics and experimental approaches were used to determine that the Drosophila silver gene corresponds to a CPD-like protein with three carboxypeptidase-like domains, a transmembrane domain, and a cytosolic tail. In addition, two alternative exons were found, which result in proteins with different carboxypeptidase-like domains, termed domains 1A and 1B. Northern blot, reverse transcriptase PCR, and sequence analysis were used to confirm the presence of the various mRNA forms. Individual domains of Drosophila CPD were expressed in insect Sf9 cells using the baculovirus expression system. Media from domain 1B- and domain 2-expressing cells showed substantial enzymatic activity, whereas medium from domain 1A-expressing cells was no different from cells infected with wild-type virus. Domains 1B and 2 were purified, and the enzymatic properties were examined. Both enzymes cleaved substrates with C-terminal Arg or Lys, but not Leu, and were inhibited by conventional metallopeptidase inhibitors and some divalent cations. Drosophila domain 1B is more active at neutral pH and greatly prefers C-terminal Arg over Lys, whereas domain 2 is more active at pH 5-6 and slightly prefers C-terminal Lys over Arg. The differences in pH optima and substrate specificity between Drosophila domains 1B and 2 are similar to the differences between duck CPD domains 1 and 2, suggesting that these properties are essential to CPD function.
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Affiliation(s)
- Galyna Sidyelyeva
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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