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Dill H, Liewald JF, Becker M, Seidenthal M, Gottschalk A. Neuropeptidergic regulation of neuromuscular signaling in larval zebrafish alters swimming behavior and synaptic transmission. iScience 2024; 27:110687. [PMID: 39252958 PMCID: PMC11381845 DOI: 10.1016/j.isci.2024.110687] [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: 01/11/2024] [Revised: 04/13/2024] [Accepted: 08/05/2024] [Indexed: 09/11/2024] Open
Abstract
Chemical synaptic transmission is modulated to accommodate different activity levels, thus enabling homeostatic scaling in pre- and postsynaptic compartments. In nematodes, cholinergic neurons use neuropeptide signaling to modulate synaptic vesicle content. To explore if this mechanism is conserved in vertebrates, we studied the involvement of neuropeptides in cholinergic transmission at the neuromuscular junction of larval zebrafish. Optogenetic stimulation by photoactivated adenylyl cyclase evoked locomotion. We generated mutants lacking the neuropeptide-processing enzyme carboxypeptidase E (cpe), and the most abundant neuropeptide precursor in motor neurons, tachykinin (tac1). Both mutants showed exaggerated locomotion after photostimulation. Recording excitatory postsynaptic currents demonstrated overall larger amplitudes in the wild type. Exaggerated locomotion in the mutants thus reflected upscaling of postsynaptic excitability. Both mutant muscles expressed more nicotinic acetylcholine receptors (nAChRs) on their surface; thus, neuropeptide signaling regulates synaptic transmitter output in zebrafish motor neurons, and muscle cells homeostatically regulate nAChR surface expression, compensating reduced presynaptic input.
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Affiliation(s)
- Holger Dill
- Buchmann Institute, Goethe University, Max-von-Laue-Strasse 15, D-60438 Frankfurt, Germany
- Institute for Biophysical Chemistry, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt, Germany
| | - Jana F Liewald
- Buchmann Institute, Goethe University, Max-von-Laue-Strasse 15, D-60438 Frankfurt, Germany
- Institute for Biophysical Chemistry, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt, Germany
| | - Michelle Becker
- Buchmann Institute, Goethe University, Max-von-Laue-Strasse 15, D-60438 Frankfurt, Germany
- Institute for Biophysical Chemistry, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt, Germany
| | - Marius Seidenthal
- Buchmann Institute, Goethe University, Max-von-Laue-Strasse 15, D-60438 Frankfurt, Germany
- Institute for Biophysical Chemistry, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt, Germany
| | - Alexander Gottschalk
- Buchmann Institute, Goethe University, Max-von-Laue-Strasse 15, D-60438 Frankfurt, Germany
- Institute for Biophysical Chemistry, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt, Germany
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2
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Štepihar D, Florke Gee RR, Hoyos Sanchez MC, Fon Tacer K. Cell-specific secretory granule sorting mechanisms: the role of MAGEL2 and retromer in hypothalamic regulated secretion. Front Cell Dev Biol 2023; 11:1243038. [PMID: 37799273 PMCID: PMC10548473 DOI: 10.3389/fcell.2023.1243038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/31/2023] [Indexed: 10/07/2023] Open
Abstract
Intracellular protein trafficking and sorting are extremely arduous in endocrine and neuroendocrine cells, which synthesize and secrete on-demand substantial quantities of proteins. To ensure that neuroendocrine secretion operates correctly, each step in the secretion pathways is tightly regulated and coordinated both spatially and temporally. At the trans-Golgi network (TGN), intrinsic structural features of proteins and several sorting mechanisms and distinct signals direct newly synthesized proteins into proper membrane vesicles that enter either constitutive or regulated secretion pathways. Furthermore, this anterograde transport is counterbalanced by retrograde transport, which not only maintains membrane homeostasis but also recycles various proteins that function in the sorting of secretory cargo, formation of transport intermediates, or retrieval of resident proteins of secretory organelles. The retromer complex recycles proteins from the endocytic pathway back to the plasma membrane or TGN and was recently identified as a critical player in regulated secretion in the hypothalamus. Furthermore, melanoma antigen protein L2 (MAGEL2) was discovered to act as a tissue-specific regulator of the retromer-dependent endosomal protein recycling pathway and, by doing so, ensures proper secretory granule formation and maturation. MAGEL2 is a mammalian-specific and maternally imprinted gene implicated in Prader-Willi and Schaaf-Yang neurodevelopmental syndromes. In this review, we will briefly discuss the current understanding of the regulated secretion pathway, encompassing anterograde and retrograde traffic. Although our understanding of the retrograde trafficking and sorting in regulated secretion is not yet complete, we will review recent insights into the molecular role of MAGEL2 in hypothalamic neuroendocrine secretion and how its dysregulation contributes to the symptoms of Prader-Willi and Schaaf-Yang patients. Given that the activation of many secreted proteins occurs after they enter secretory granules, modulation of the sorting efficiency in a tissue-specific manner may represent an evolutionary adaptation to environmental cues.
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Affiliation(s)
- Denis Štepihar
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Rebecca R. Florke Gee
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
| | - Maria Camila Hoyos Sanchez
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
| | - Klementina Fon Tacer
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
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3
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SORLA mediates endocytic uptake of proIAPP and protects against islet amyloid deposition. Mol Metab 2022; 65:101585. [PMID: 36055578 PMCID: PMC9474563 DOI: 10.1016/j.molmet.2022.101585] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/27/2022] [Accepted: 08/25/2022] [Indexed: 11/20/2022] Open
Abstract
Objective Sorting-related receptor with type A repeats (SORLA) is a neuronal sorting receptor that prevents accumulation of amyloid-beta peptides, the main constituent of senile plaques in Alzheimer disease. Recent transcriptomic studies show that SORLA transcripts are also found in beta cells of pancreatic islets, yet the role of SORLA in islets is unknown. Based on its protective role in reducing the amyloid burden in the brain, we hypothesized that SORLA has a similar function in the pancreas via regulation of amyloid formation from islet amyloid polypeptide (IAPP). Methods We generated human IAPP transgenic mice lacking SORLA (hIAPP:SORLA KO) to assess the consequences of receptor deficiency for islet histopathology and function in vivo. Using both primary islet cells and cell lines, we further investigated the molecular mechanisms whereby SORLA controls the cellular metabolism and accumulation of IAPP. Results Loss of SORLA activity in hIAPP:SORLA KO resulted in a significant increase in islet amyloid deposits and associated islet cell death compared to hIAPP:SORLA WT animals. Aggravated islet amyloid deposition was observed in mice fed a normal chow diet, not requiring high-fat diet feeding typically needed to induce islet amyloidosis in mouse models. In vitro studies showed that SORLA binds to and mediates the endocytic uptake of proIAPP, but not mature IAPP, delivering the propeptide to an endolysosomal fate. Conclusions SORLA functions as a proIAPP-specific clearance receptor, protecting against islet amyloid deposition and associated cell death caused by IAPP. SORLA is an endocytic receptor for amyloidogenic peptides expressed in islet beta cells. SORLA mediates cellular clearance of proIAPP. Loss of SORLA activity in mouse models causes spontaneous islet amyloid deposition.
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Zhang X, Zhao P, Li S, Ma S, Du J, Liang S, Yang X, Yao L, Duan J. Genome-Wide Identification of M14 Family Metal Carboxypeptidases in Antheraea pernyi (Lepidoptera: Saturniidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:1285-1293. [PMID: 35640220 DOI: 10.1093/jee/toac081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Indexed: 06/15/2023]
Abstract
The M14 family metal carboxypeptidase genes play an important role in digestion and pathogenic infections in the gut of insects. However, the roles of these genes in Antheraea pernyi (Guérin-Méneville, 1855) remain to be analyzed. In the present study, we cloned a highly expressed M14 metal carboxypeptidase gene (ApMCP1) found in the gut and discovered that it contained a 1,194 bp open reading frame encoding a 397-amino acid protein with a predicted molecular weight of 45 kDa. Furthermore, 14 members of the M14 family metal carboxypeptidases (ApMCP1-ApMCP14) were identified in the A. pernyi genome, with typical Zn_pept domains and two Zn-anchoring motifs, and were further classified into M14A, M14B, and M14D subfamilies. Expression analysis indicated that ApMCP1 and ApMCP9 were mainly expressed in the gut. Additionally, we observed that ApMCP1 and ApMCP9 displayed opposite expression patterns after starvation, highlighting their functional divergence during digestion. Following natural infection with baculovirus NPV, their expression was significantly upregulated in the gut of A. pernyi. Our results suggest that the M14 family metal carboxypeptidase genes are conservatively digestive enzymes and evolutionarily involved in exogenous pathogenic infections.
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Affiliation(s)
- Xian Zhang
- Henan Key Laboratory of Funiu Mountain Insect Biology, College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang 473061, PR China
| | - Ping Zhao
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, PR China
| | - Shanshan Li
- Henan Key Laboratory of Funiu Mountain Insect Biology, College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang 473061, PR China
| | - Sanyuan Ma
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, PR China
| | - Jie Du
- Henan Key Laboratory of Funiu Mountain Insect Biology, College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang 473061, PR China
| | - Shimei Liang
- Henan Key Laboratory of Funiu Mountain Insect Biology, College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang 473061, PR China
| | - Xinfeng Yang
- Laboratory of Tussah Genetics and Breeding, Henan Institute of Sericulture Science, Zhengzhou 450008, PR China
| | - Lunguang Yao
- Henan Key Laboratory of Funiu Mountain Insect Biology, College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang 473061, PR China
| | - Jianping Duan
- Henan Key Laboratory of Funiu Mountain Insect Biology, College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang 473061, PR China
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Navarro-Tableros V, Gai C, Gomez Y, Giunti S, Pasquino C, Deregibus MC, Tapparo M, Pitino A, Tetta C, Brizzi MF, Ricordi C, Camussi G. Islet-Like Structures Generated In Vitro from Adult Human Liver Stem Cells Revert Hyperglycemia in Diabetic SCID Mice. Stem Cell Rev Rep 2020; 15:93-111. [PMID: 30191384 PMCID: PMC6510809 DOI: 10.1007/s12015-018-9845-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A potential therapeutic strategy for diabetes is the transplantation of induced-insulin secreting cells. Based on the common embryonic origin of liver and pancreas, we studied the potential of adult human liver stem-like cells (HLSC) to generate in vitro insulin-producing 3D spheroid structures (HLSC-ILS). HLSC-ILS were generated by a one-step protocol based on charge dependent aggregation of HLSC induced by protamine. 3D aggregation promoted the spontaneous differentiation into cells expressing insulin and several key markers of pancreatic β cells. HLSC-ILS showed endocrine granules similar to those seen in human β cells. In static and dynamic in vitro conditions, such structures produced C-peptide after stimulation with high glucose. HLSC-ILS significantly reduced hyperglycemia and restored a normo-glycemic profile when implanted in streptozotocin-diabetic SCID mice. Diabetic mice expressed human C-peptide and very low or undetectable levels of murine C-peptide. Hyperglycemia and a diabetic profile were restored after HLSC-ISL explant. The gene expression profile of in vitro generated HLSC-ILS showed a differentiation from HLSC profile and an endocrine commitment with the enhanced expression of several markers of β cell differentiation. The comparative analysis of gene expression profiles after 2 and 4 weeks of in vivo implantation showed a further β-cell differentiation, with a genetic profile still immature but closer to that of human islets. In conclusion, protamine-induced spheroid aggregation of HLSC triggers a spontaneous differentiation to an endocrine phenotype. Although the in vitro differentiated HLSC-ILS were immature, they responded to high glucose with insulin secretion and in vivo reversed hyperglycemia in diabetic SCID mice.
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Affiliation(s)
- Victor Navarro-Tableros
- 2i3T - Scarl.-Molecular Biotechnology Center (MBC), University of Turin, Via Nizza, 52, 10126, Turin, Italy
| | - Chiara Gai
- Department of Medical Sciences, University of Turin, Corso Dogliotti 14, 10126, Turin, Italy.,Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy
| | - Yonathan Gomez
- Department of Medical Sciences, University of Turin, Corso Dogliotti 14, 10126, Turin, Italy.,Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy
| | - Sara Giunti
- Department of Medical Sciences, University of Turin, Corso Dogliotti 14, 10126, Turin, Italy.,Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy
| | - Chiara Pasquino
- Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy.,Molecular Biotechnology and Health Sciences, MBC, Via Nizza, 52, 10126, Turin, Italy
| | - Maria Chiara Deregibus
- 2i3T - Scarl.-Molecular Biotechnology Center (MBC), University of Turin, Via Nizza, 52, 10126, Turin, Italy
| | - Marta Tapparo
- Department of Medical Sciences, University of Turin, Corso Dogliotti 14, 10126, Turin, Italy.,Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy
| | - Adriana Pitino
- Molecular Biotechnology and Health Sciences, MBC, Via Nizza, 52, 10126, Turin, Italy
| | | | - Maria Felice Brizzi
- Department of Medical Sciences, University of Turin, Corso Dogliotti 14, 10126, Turin, Italy.,Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy
| | - Camillo Ricordi
- Diabetes Research Institute, University of Miami, Miami, FL, USA
| | - Giovanni Camussi
- Department of Medical Sciences, University of Turin, Corso Dogliotti 14, 10126, Turin, Italy. .,Fondazione per la Ricerca Biomedica-ONLUS, Via Nizza, 52, 10126, Turin, Italy.
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6
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Yang X, Lou H, Chen YT, Huang SF, Loh YP. A novel 40kDa N-terminal truncated carboxypeptidase E splice variant: cloning, cDNA sequence analysis and role in regulation of metastatic genes in human cancers. Genes Cancer 2019; 10:160-170. [PMID: 31798768 PMCID: PMC6872665 DOI: 10.18632/genesandcancer.193] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Carboxypeptidase E (CPE), a prohormone processing enzyme, is a 476- amino acid protein with a signal peptide in its N-terminus and is expressed in the nervous and the endocrine systems. Recent evidence indicate CPE plays various non-enzymatic roles in the endocrine and nervous systems and in various cancers. Besides wild type (WT) CPE, a 40-kDa CPE protein that localizes in the nucleus and cytoplasm has been described in embryonic mouse brain. In this study we have cloned this CPE variant encoding the 40kDa CPE-ΔN protein from human cancer cells. RACE assay and sequence analysis confirmed existence of this CPE variant mRNA, which has 198 nucleotides removed within the first exon and 589 nucleotides from the 3’-UTR, respectively, compared to WT-CPE mRNA. Bioinformatic analysis revealed that this CPE variant mRNA has a shortened open reading frame, which starts coding from the 3rd ATG relative to WT-CPE mRNA and encodes a 40kDa N-terminus truncated CPE protein. RT-PCR and Western blot analysis showed that 40kDa CPE-ΔN is expressed in multiple cancer cell lines and tumor tissues. Overexpression of this 40kDa CPE-ΔN variant up-regulated expression of multiple metastatic genes encompassing different signaling pathways, suggesting potentially an important role of CPE-ΔN in tumor metastasis.
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Affiliation(s)
- Xuyu Yang
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Hong Lou
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Ya-Ting Chen
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhuna, Miaoli, Taiwan
| | - Shui-Feng Huang
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhuna, Miaoli, Taiwan.,Department of Anatomical Pathology, Chung-Shan Medical University Hospital, Taichung, Taiwan
| | - Y Peng Loh
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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Harno E, Gali Ramamoorthy T, Coll AP, White A. POMC: The Physiological Power of Hormone Processing. Physiol Rev 2019; 98:2381-2430. [PMID: 30156493 DOI: 10.1152/physrev.00024.2017] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pro-opiomelanocortin (POMC) is the archetypal polypeptide precursor of hormones and neuropeptides. In this review, we examine the variability in the individual peptides produced in different tissues and the impact of the simultaneous presence of their precursors or fragments. We also discuss the problems inherent in accurately measuring which of the precursors and their derived peptides are present in biological samples. We address how not being able to measure all the combinations of precursors and fragments quantitatively has affected our understanding of the pathophysiology associated with POMC processing. To understand how different ratios of peptides arise, we describe the role of the pro-hormone convertases (PCs) and their tissue specificities and consider the cellular processing pathways which enable regulated secretion of different peptides that play crucial roles in integrating a range of vital physiological functions. In the pituitary, correct processing of POMC peptides is essential to maintain the hypothalamic-pituitary-adrenal axis, and this processing can be disrupted in POMC-expressing tumors. In hypothalamic neurons expressing POMC, abnormalities in processing critically impact on the regulation of appetite, energy homeostasis, and body composition. More work is needed to understand whether expression of the POMC gene in a tissue equates to release of bioactive peptides. We suggest that this comprehensive view of POMC processing, with a focus on gaining a better understanding of the combination of peptides produced and their relative bioactivity, is a necessity for all involved in studying this fascinating physiological regulatory phenomenon.
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Affiliation(s)
- Erika Harno
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Thanuja Gali Ramamoorthy
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anthony P Coll
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anne White
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
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8
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Li M, Du W, Zhou M, Zheng L, Song E, Hou J. Proteomic analysis of insulin secretory granules in INS-1 cells by protein correlation profiling. BIOPHYSICS REPORTS 2018; 4:329-338. [PMID: 30596141 PMCID: PMC6276070 DOI: 10.1007/s41048-018-0061-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 07/08/2018] [Indexed: 11/30/2022] Open
Abstract
Abstract Insulin secretory granules (ISGs), a group of distinguishing organelles in pancreatic β cells, are responsible for the storage and secretion of insulin to maintain blood glucose homeostasis. The molecular mechanisms of ISG biogenesis, maturation, transportation, and exocytosis are still largely unknown because the proteins involved in these distinct steps have not been fully identified. Subcellular fractionation by density gradient centrifugation has been successfully employed to analyze the proteomes of numerous organelles. However, use of this method to elucidate the ISG proteome is limited by co-fractionated contaminants because ISGs are very dynamic and have abundant exchanges or contacts with other organelles, such as the Golgi apparatus, lysosomes, and endosomes. In this study, we developed a new strategy for identifying ISG proteins by protein correlation profiling (PCP)-based proteomics, which included ISG purification by OptiPrep density gradient centrifugation, label-free quantitative proteome, and identification of ISG proteins by correlating fractionation profiles between candidates and known ISG markers. Using this approach, we were able to identify 81 ISG proteins. Among them, TM9SF3, a nine-transmembrane protein, was considered a high confidence ISG candidate protein highlighted in the PCP network. Further biochemical and immunofluorescence assays indicated that TM9SF3 localized in ISGs, suggesting that it is a potential new ISG marker. Graphical abstract ![]()
Electronic supplementary material The online version of this article (10.1007/s41048-018-0061-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Min Li
- 1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.,2College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Wen Du
- 1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Maoge Zhou
- 1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Li Zheng
- 1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Eli Song
- 1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Junjie Hou
- 1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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9
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Podvin S, Wojnicz A, Hook V. Human brain gene expression profiles of the cathepsin V and cathepsin L cysteine proteases, with the PC1/3 and PC2 serine proteases, involved in neuropeptide production. Heliyon 2018; 4:e00673. [PMID: 29998195 PMCID: PMC6037879 DOI: 10.1016/j.heliyon.2018.e00673] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 06/06/2018] [Accepted: 06/26/2018] [Indexed: 11/09/2022] Open
Abstract
Proteases are required to generate active peptide neurotransmitters, known as neuropeptides, from pro-neuropeptides. Model animal systems have recently illustrated roles for the cathepsin V (CTSV) and cathepsin L (CTSL) cysteine proteases, combined with the serine proteases PC1/3 (PCSK1) and PC2 (PCSK2), and exopeptidases in the production of neuropeptides. There is notable interest in the human-specific cathepsin V gene which is not present in rodent and other animal models used in prior studies of neuropeptide production. A gap in the field is knowledge of the human brain gene expression patterns of these neuropeptide-producing protease systems. Therefore, the goal of this study was to characterize the expression profiles of these pro-neuropeptide processing proteases in human brain. Quantitative gene expression microarray data for 169 human brain regions was obtained from the Allen Institute Human Brain Atlas resource, analyzed as log2 of gene expression intensity normalized to the mean of human genes (21,245 genes) expressed in human brain. These proteases had log2 values of 2–12, indicating expression levels above the average of all genes in the human brain, with varying expression levels among the 169 brain regions. CTSV and CTSL displayed moderate to high expression values of 1.9–8.6 and 7.1–10.6, respectively. Interestingly, CTSV and CTSL showed high expression in white matter composed of myelinated axons, consistent with the knowledge that neuropeptide production occurs in axons within transported neuropeptide secretory vesicles to nerve terminals. PCSK1 had a broad range of moderate to very high expression with log2 of 2–12. PCSK2 had somewhat lower expression levels than PCSK1. The exopeptidase genes RNPEP, CTSH, and CPE each showed fairly even levels of expression throughout the brain, with CPE displaying high expression. The prevalence of these processing proteases throughout human brain regions, including areas rich in neuropeptides such as hypothalamus, is consistent with their roles for neuropeptide production. Further, proenkephalin and NPY precursors, substrates of CTSV and CTSL shown in prior model animal studies, were co-expressed with CTSV and CTSL. These data demonstrate that the human brain expresses the neuropeptide-producing cysteine and serine proteases, with exopeptidases, throughout a multitude of brain regions.
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Affiliation(s)
- Sonia Podvin
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Division of Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Aneta Wojnicz
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Division of Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Vivian Hook
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Division of Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA.,School of Medicine, Dept. of Neurosciences, University of California San Diego, La Jolla, California, USA.,School of Medicine, Dept. of Pharmacology, University of California San Diego, La Jolla, California, USA
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10
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Stephens SB, Edwards RJ, Sadahiro M, Lin WJ, Jiang C, Salton SR, Newgard CB. The Prohormone VGF Regulates β Cell Function via Insulin Secretory Granule Biogenesis. Cell Rep 2018; 20:2480-2489. [PMID: 28877479 DOI: 10.1016/j.celrep.2017.08.050] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 07/25/2017] [Accepted: 08/15/2017] [Indexed: 12/18/2022] Open
Abstract
The prohormone VGF is expressed in neuroendocrine and endocrine tissues and regulates nutrient and energy status both centrally and peripherally. We and others have shown that VGF-derived peptides have direct action on the islet β cell as secretagogues and cytoprotective agents; however, the endogenous function of VGF in the β cell has not been described. Here, we demonstrate that VGF regulates secretory granule formation. VGF loss-of-function studies in both isolated islets and conditional knockout mice reveal a profound decrease in stimulus-coupled insulin secretion. Moreover, VGF is necessary to facilitate efficient exit of granule cargo from the trans-Golgi network and proinsulin processing. It also functions to replenish insulin granule stores following nutrient stimulation. Our data support a model in which VGF operates at a critical node of granule biogenesis in the islet β cell to coordinate insulin biosynthesis with β cell secretory capacity.
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Affiliation(s)
- Samuel B Stephens
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27704, USA; Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27704, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27704, USA.
| | - Robert J Edwards
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27704, USA
| | - Masato Sadahiro
- Department of Neuroscience, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA; Graduate School of Biomedical Sciences, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA
| | - Wei-Jye Lin
- Department of Neuroscience, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA
| | - Cheng Jiang
- Department of Neuroscience, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA; Graduate School of Biomedical Sciences, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA
| | - Stephen R Salton
- Department of Neuroscience, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA; Friedman Brain Institute, Icahn School of Medicine at Mt. Sinai, New York, NY 10029, USA
| | - Christopher B Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27704, USA; Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27704, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27704, USA; Department of Medicine, Division of Endocrinology, Duke University Medical Center, Durham, NC 27704, USA
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11
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Anterior Pituitary Transcriptome Suggests Differences in ACTH Release in Tame and Aggressive Foxes. G3-GENES GENOMES GENETICS 2018; 8:859-873. [PMID: 29378821 PMCID: PMC5844307 DOI: 10.1534/g3.117.300508] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Domesticated species exhibit a suite of behavioral, endocrinological, and morphological changes referred to as "domestication syndrome." These changes may include a reduction in reactivity of the hypothalamic-pituitary-adrenal (HPA) axis and specifically reduced adrenocorticotropic hormone release from the anterior pituitary. To investigate the biological mechanisms targeted during domestication, we investigated gene expression in the pituitaries of experimentally domesticated foxes (Vulpes vulpes). RNA was sequenced from the anterior pituitary of six foxes selectively bred for tameness ("tame foxes") and six foxes selectively bred for aggression ("aggressive foxes"). Expression, splicing, and network differences identified between the two lines indicated the importance of genes related to regulation of exocytosis, specifically mediated by cAMP, organization of pseudopodia, and cell motility. These findings provide new insights into biological mechanisms that may have been targeted when these lines of foxes were selected for behavior and suggest new directions for research into HPA axis regulation and the biological underpinnings of domestication.
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12
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Molecular regulation of insulin granule biogenesis and exocytosis. Biochem J 2017; 473:2737-56. [PMID: 27621482 DOI: 10.1042/bcj20160291] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/19/2016] [Indexed: 12/15/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by hyperglycemia, insulin resistance and hyperinsulinemia in early disease stages but a relative insulin insufficiency in later stages. Insulin, a peptide hormone, is produced in and secreted from pancreatic β-cells following elevated blood glucose levels. Upon its release, insulin induces the removal of excessive exogenous glucose from the bloodstream primarily by stimulating glucose uptake into insulin-dependent tissues as well as promoting hepatic glycogenesis. Given the increasing prevalence of T2DM worldwide, elucidating the underlying mechanisms and identifying the various players involved in the synthesis and exocytosis of insulin from β-cells is of utmost importance. This review summarizes our current understanding of the route insulin takes through the cell after its synthesis in the endoplasmic reticulum as well as our knowledge of the highly elaborate network that controls insulin release from the β-cell. This network harbors potential targets for anti-diabetic drugs and is regulated by signaling cascades from several endocrine systems.
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13
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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: 42] [Impact Index Per Article: 6.0] [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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14
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Vernigora AN, Volkova NV, Saldaev DA. The effects of sex steroid hormones on the activities of basic carboxypeptidases in the hypothalamo–pituitary–adrenal system of male and female mice after stress. NEUROCHEM J+ 2017. [DOI: 10.1134/s1819712416040140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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15
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Sun J, Meng D, Li L, Tian X, Jia Y, Wang H, Yu H, Sun T, Qu A, Shen H, Bao J, Zhang G. N-terminal truncated carboxypeptidase E expression is associated with poor prognosis of lung adenocarcinoma. Oncol Lett 2016; 12:4659-4664. [PMID: 28101219 DOI: 10.3892/ol.2016.5283] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/09/2016] [Indexed: 01/23/2023] Open
Abstract
Lung cancer is a malignant tumor with high morbidity and mortality rates. To date, no suitable molecular diagnostic tool to predict disease recurrence and metastasis has been identified. The current study aimed to evaluate the potential of N-terminal truncated carboxypeptidase E (CPEΔN) to predict the recurrence and metastasis of lung adenocarcinoma. Western blotting revealed the co-expression of CPE and CPEΔN in the surgically collected pathological and pericarcinoma tissues tissues of 62.1% (59/95) lung adenocarcinoma patients. The full length CPE protein was predominantly expressed in pericarcinoma tissues and CPEΔN expression was identified in the pericarcinoma normal tissues of only 5.26% (5/95) patients. The 3-year postoperative recurrence and metastasis rates were significantly higher in patients with positive CPEΔN expression than in patients with negative CPEΔN expression (P=0.009). Furthermore, the overall survival rate of patients with predominant nuclear CPE expression was lower than that of patients with predominant cytoplasmic CPE expression (46.3 vs. 64.7%); however, no statistically significant difference was identified (P=0.125). Thus, the results of the current study indicated that CPEΔN may present a novel molecular biomarker for predicting recurrence and metastasis of lung adenocarcinoma, which may aid with stratifying patients by risk and thus, may facilitate individualized therapy.
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Affiliation(s)
- Jing Sun
- Cancer Hospital of China Medical University, Shenyang, Liaoning 110042, P.R. China; Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
| | - Dawei Meng
- Department of Otolaryngology-Head and Neck Surgery, Jinqiu Hospital of Liaoning Province, Shenyang, Liaoning 110016, P.R. China
| | - Li Li
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, P.R. China
| | - Xin Tian
- Molecular Oncology Laboratory, Cancer Research Institute, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yunji Jia
- Department of General Surgery, Central Hospital Affiliated to Shenyang Medical College, Shenyang, Liaoning 110024, P.R. China
| | - Hongyue Wang
- Cancer Hospital of China Medical University, Shenyang, Liaoning 110042, P.R. China; Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
| | - Huihui Yu
- Department of Epidemiology, Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
| | - Tiemin Sun
- Cancer Hospital of China Medical University, Shenyang, Liaoning 110042, P.R. China; Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
| | - Aibing Qu
- Cancer Hospital of China Medical University, Shenyang, Liaoning 110042, P.R. China; Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
| | - Hui Shen
- Cancer Hospital of China Medical University, Shenyang, Liaoning 110042, P.R. China; Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
| | - Jimin Bao
- Department of Otolaryngology-Head and Neck Surgery, Jinqiu Hospital of Liaoning Province, Shenyang, Liaoning 110016, P.R. China
| | - Guirong Zhang
- Cancer Hospital of China Medical University, Shenyang, Liaoning 110042, P.R. China; Liaoning Cancer Hospital and Institute, Shenyang, Liaoning 110042, P.R. China
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16
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Mizutani A, Inoko H, Tanaka M. Carboxypeptidase E, Identified As a Direct Interactor of Growth Hormone, Is Important for Efficient Secretion of the Hormone. Mol Cells 2016; 39:756-761. [PMID: 27788574 PMCID: PMC5104884 DOI: 10.14348/molcells.2016.0183] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/09/2016] [Accepted: 09/22/2016] [Indexed: 11/27/2022] Open
Abstract
We have identified 88 interactor candidates for human growth hormone (GH) by the yeast two-hybrid assay. Among those, we focused our efforts on carboxypeptidase E (CPE), which has been thought to play a key role in sorting prohormones, such as pro-opiomelanocortin (POMC), to regulated secretory vesicles. We found that CPE co-localizes with and interacts with GH in AtT20 pituitary cells. Downregulation of CPE led to decreased levels of GH secretion, consistent with involvement of CPE in GH sorting/secretion. Our binding assay in vitro with bacterially expressed proteins suggested that GH directly interacts with CPE but in a manner different from POMC.
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Affiliation(s)
- Akiko Mizutani
- Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Isehara, Kanagawa 259-1193,
Japan
- Faculty of Health and Medical Science, Teikyo Heisei University, Higashi-Ikebukuro, Toshima, Tokyo 170-8445,
Japan
| | - Hidetoshi Inoko
- Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Isehara, Kanagawa 259-1193,
Japan
| | - Masafumi Tanaka
- Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Isehara, Kanagawa 259-1193,
Japan
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17
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Genome-Wide Identification and Characterization of Carboxypeptidase Genes in Silkworm (Bombyx mori). Int J Mol Sci 2016; 17:ijms17081203. [PMID: 27483237 PMCID: PMC5000601 DOI: 10.3390/ijms17081203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/14/2016] [Accepted: 07/19/2016] [Indexed: 11/17/2022] Open
Abstract
The silkworm (Bombyx mori) is an economically-important insect that can secrete silk. Carboxypeptidases have been found in various metazoan species and play important roles in physiological and biochemical reactions. Here, we analyzed the silkworm genome database and characterized 48 carboxypeptidases, including 34 metal carboxypeptidases (BmMCP1-BmMCP34) and 14 serine carboxypeptidases (BmSCP1-BmSCP14), to better understand their diverse functions. Compared to other insects, our results indicated that carboxypeptidases from silkworm have more family members. These silkworm carboxypeptidases could be divided into four families: Peptidase_M2 carboxypeptidases, Peptidase_M14 carboxypeptidases, Peptidase_S10 carboxypeptidases and Peptidase_S28 carboxypeptidases. Microarray analysis showed that the carboxypeptidases had distinct expression patterns, whereas quantitative real-time PCR demonstrated that the expression level of 13 carboxypeptidases significantly decreased after starvation and restored after re-feeding. Overall, our study provides new insights into the functional and evolutionary features of silkworm carboxypeptidases.
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18
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Cawley NX, Li Z, Loh YP. 60 YEARS OF POMC: Biosynthesis, trafficking, and secretion of pro-opiomelanocortin-derived peptides. J Mol Endocrinol 2016; 56:T77-97. [PMID: 26880796 PMCID: PMC4899099 DOI: 10.1530/jme-15-0323] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 12/15/2022]
Abstract
Pro-opiomelanocortin (POMC) is a prohormone that encodes multiple smaller peptide hormones within its structure. These peptide hormones can be generated by cleavage of POMC at basic residue cleavage sites by prohormone-converting enzymes in the regulated secretory pathway (RSP) of POMC-synthesizing endocrine cells and neurons. The peptides are stored inside the cells in dense-core secretory granules until released in a stimulus-dependent manner. The complexity of the regulation of the biosynthesis, trafficking, and secretion of POMC and its peptides reflects an impressive level of control over many factors involved in the ultimate role of POMC-expressing cells, that is, to produce a range of different biologically active peptide hormones ready for action when signaled by the body. From the discovery of POMC as the precursor to adrenocorticotropic hormone (ACTH) and β-lipotropin in the late 1970s to our current knowledge, the understanding of POMC physiology remains a monumental body of work that has provided insight into many aspects of molecular endocrinology. In this article, we describe the intracellular trafficking of POMC in endocrine cells, its sorting into dense-core secretory granules and transport of these granules to the RSP. Additionally, we review the enzymes involved in the maturation of POMC to its various peptides and the mechanisms involved in the differential processing of POMC in different cell types. Finally, we highlight studies pertaining to the regulation of ACTH secretion in the anterior and intermediate pituitary and POMC neurons of the hypothalamus.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Zhaojin Li
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Y Peng Loh
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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19
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Cawley NX, Rathod T, Young S, Lou H, Birch N, Loh YP. Carboxypeptidase E and Secretogranin III Coordinately Facilitate Efficient Sorting of Proopiomelanocortin to the Regulated Secretory Pathway in AtT20 Cells. Mol Endocrinol 2015; 30:37-47. [PMID: 26646096 DOI: 10.1210/me.2015-1166] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Proopiomelanocortin (POMC) is a multivalent prohormone that can be processed into at least 7 biologically active peptide hormones. Processing can begin in the trans-Golgi network (TGN) and continues in the secretory granules of the regulated secretory pathway (RSP). Sorting of POMC into these granules is a complex process. Previously, a membrane-associated form of carboxypeptidase E (CPE) was shown to bind to POMC and facilitate its trafficking into these granules. More recently, secretogranin III (SgIII) was also found to affect POMC trafficking. Here, we show by RNA silencing that CPE and SgIII play a synergistic role in the trafficking of POMC to granules of the RSP in AtT20 cells. Reduction of either protein resulted in increased constitutive secretion of POMC and chromogranin A, which was increased even further when both proteins were reduced together, indicative of missorting at the TGN. In SgIII-reduced cells, POMC accumulated in a compartment that cofractionated and colocalized with syntaxin 6, a marker of the TGN, on sucrose density gradients and in immunocytochemistry, respectively, indicating an accumulation of this protein in the presumed sorting compartment. Regulated secretion of ACTH, as a measure of sorting and processing of POMC in mature granules, was reduced in the SgIII down-regulated cells but was increased in the CPE down-regulated cells. These results suggest that multiple sorting systems exist, providing redundancy to ensure the important task of continuous and accurate trafficking of prohormones to the granules of the RSP for the production of peptide hormones.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Trushar Rathod
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Sigrid Young
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Hong Lou
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Nigel Birch
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Y Peng Loh
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
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20
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Kienzle C, von Blume J. Secretory cargo sorting at the trans-Golgi network. Trends Cell Biol 2014; 24:584-93. [DOI: 10.1016/j.tcb.2014.04.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 04/15/2014] [Accepted: 04/16/2014] [Indexed: 12/22/2022]
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21
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Bär F, Föh B, Pagel R, Schröder T, Schlichting H, Hirose M, Lemcke S, Klinger A, König P, Karsten CM, Büning J, Lehnert H, Fellermann K, Ibrahim SM, Sina C. Carboxypeptidase E modulates intestinal immune homeostasis and protects against experimental colitis in mice. PLoS One 2014; 9:e102347. [PMID: 25051500 PMCID: PMC4106776 DOI: 10.1371/journal.pone.0102347] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 06/18/2014] [Indexed: 12/24/2022] Open
Abstract
Enteroendocrine cells (EEC) produce neuropeptides, which are crucially involved in the maintenance of the intestinal barrier. Hence, EEC dysfunction is suggested to be involved in the complex pathophysiology of inflammatory bowel disease (IBD), which is characterized by decreased intestinal barrier function. However, the underlying mechanisms for EEC dysfunction are not clear and suitable models for a better understanding are lacking. Here, we demonstrate that Carboxypeptidase E (CPE) is specifically expressed in EEC of the murine colon and ileum and that its deficiency is associated with reduced intestinal levels of Neuropeptide Y (NPY) and Peptide YY (PYY), which are both produced by EEC. Moreover, cpe−/− mice exhibit an aggravated course of DSS-induced chronic colitis compared to wildtype littermates. In addition, we observed elevated mucosal IL-6 and KC transcript levels already at baseline conditions in cpe−/− mice. Moreover, supernatants obtained from isolated intestinal crypts of cpe−/− mice lead to increased IL-6 and KC expression in MODE-K cells in the presence of LPS. This effect was reversible by co-administration of recombinant NPY, suggesting a CPE mediated immunosuppressive effect in the intestines by influencing the processing of specific neuropeptides. In this context, the chemotaxis of bone marrow derived macrophages towards respective supernatants was enhanced. In conclusion, our data point to an anti-inflammatory role of CPE in the intestine by influencing local cytokine levels and thus regulating the migration of myeloid immune cells into the mucosa. These findings highlight the importance of EEC for intestinal homeostasis and propose EEC as potential therapeutic targets in IBD.
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Affiliation(s)
- Florian Bär
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
- Institute of Anatomy, University of Lübeck, Lübeck, Germany
| | - Bandik Föh
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - René Pagel
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Torsten Schröder
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Heidi Schlichting
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Misa Hirose
- Department of Dermatology, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Susanne Lemcke
- Department of Dermatology, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Antje Klinger
- Institute of Anatomy, University of Lübeck, Lübeck, Germany
| | - Peter König
- Institute of Anatomy, University of Lübeck, Lübeck, Germany
| | - Christian M. Karsten
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany
| | - Jürgen Büning
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Hendrik Lehnert
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Klaus Fellermann
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Saleh M. Ibrahim
- Department of Dermatology, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Christian Sina
- Medical Department I, University Hospital Schleswig-Holstein, Lübeck, Germany
- * E-mail:
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22
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Liu M, Wright J, Guo H, Xiong Y, Arvan P. Proinsulin entry and transit through the endoplasmic reticulum in pancreatic beta cells. VITAMINS AND HORMONES 2014; 95:35-62. [PMID: 24559913 DOI: 10.1016/b978-0-12-800174-5.00002-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Insulin is an essential hormone for maintaining metabolic homeostasis in the body. To make fully bioactive insulin, pancreatic beta cells initiate synthesis of the insulin precursor, preproinsulin, at the cytosolic side of the endoplasmic reticulum (ER), whereupon it undergoes co- and post-translational translocation across the ER membrane. Preproinsulin is cleaved by signal peptidase to form proinsulin that folds on the luminal side of the ER, forming three evolutionarily conserved disulfide bonds. Properly folded proinsulin forms dimers and exits from the ER, trafficking through Golgi complex into immature secretory granules wherein C-peptide is endoproteolytically excised, allowing fully bioactive two-chain insulin to ultimately be stored in mature granules for insulin secretion. Although insulin biosynthesis has been intensely studied in recent decades, the earliest events, including proinsulin entry and exit from the ER, have been relatively understudied. However, over the past 5 years, more than 20 new insulin gene mutations have been reported to cause a new syndrome termed Mutant INS-gene-induced Diabetes of Youth (MIDY). Although these mutants have not been completely characterized, most of them affect proinsulin entry and exit from the ER. Here, we summarize our current knowledge about the early events of insulin biosynthesis and review recent advances in understanding how defects in these events may lead to pancreatic beta cell failure.
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Affiliation(s)
- Ming Liu
- Division of Metabolism, Endocrinology & Diabetes, The University of Michigan Medical School, Ann Arbor, Michigan, USA; Department of Metabolism, Tianjin Medical University General Hospital, Tianjin, PR China.
| | - Jordan Wright
- Division of Metabolism, Endocrinology & Diabetes, The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Huan Guo
- Division of Metabolism, Endocrinology & Diabetes, The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yi Xiong
- Division of Metabolism, Endocrinology & Diabetes, The University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, The University of Michigan Medical School, Ann Arbor, Michigan, USA.
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23
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Ager-Wick E, Dirks RP, Burgerhout E, Nourizadeh-Lillabadi R, de Wijze DL, Spaink HP, van den Thillart GEEJM, Tsukamoto K, Dufour S, Weltzien FA, Henkel CV. The pituitary gland of the European eel reveals massive expression of genes involved in the melanocortin system. PLoS One 2013; 8:e77396. [PMID: 24130881 PMCID: PMC3795071 DOI: 10.1371/journal.pone.0077396] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 09/02/2013] [Indexed: 11/18/2022] Open
Abstract
Hormones secreted from the pituitary gland regulate important processes such as development, growth and metabolism, reproduction, water balance, and body pigmentation. Synthesis and secretion of pituitary hormones are regulated by different factors from the hypothalamus, but also through feedback mechanisms from peripheral organs, and from the pituitary itself. In the European eel extensive attention has been directed towards understanding the different components of the brain-pituitary-gonad axis, but little is known about the regulation of upstream processes in the pituitary gland. In order to gain a broader mechanistic understanding of the eel pituitary gland, we have performed RNA-seq transcriptome profiling of the pituitary of prepubertal female silver eels. RNA-seq reads generated on the Illumina platform were mapped to the recently assembled European eel genome. The most abundant transcript in the eel pituitary codes for pro-opiomelanocortin, the precursor for hormones of the melanocortin system. Several genes putatively involved in downstream processing of pro-opiomelanocortin were manually annotated, and were found to be highly expressed, both by RNA-seq and by qPCR. The melanocortin system, which affects skin color, energy homeostasis and in other teleosts interacts with the reproductive system, has so far received limited attention in eels. However, since up to one third of the silver eel pituitary's mRNA pool encodes pro-opiomelanocortin, our results indicate that control of the melanocortin system is a major function of the eel pituitary.
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Affiliation(s)
- Eirill Ager-Wick
- Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Oslo, Norway
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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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25
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Carboxypeptidase E: elevated expression correlated with tumor growth and metastasis in pheochromocytomas and other cancers. Cell Mol Neurobiol 2011; 30:1377-81. [PMID: 21061162 DOI: 10.1007/s10571-010-9592-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 09/02/2010] [Indexed: 12/20/2022]
Abstract
Expression of carboxypeptidase E (CPE), a prohormone processing enzyme in different cancer types, was analyzed from data in the GEO profile database (http://www.ncbi.nlm.nih.gov/geo/) and experimentally in pheochromocytomas. Analysis of microarray data demonstrated that significantly elevated levels of CPE mRNA was found in many metastatic non-endocrine cancers: cervical, colon rectal, renal cancers, Ewing sarcomas (bone cancer), and various types of astrocytomas and oligodendrogliomas, whereas expression of CPE mRNA was virtually absent in their respective counterpart normal tissues. Moreover, there was higher CPE mRNA expression in cells from the metastatic tumor compared to those from the primary tumor in colorectal cancer. Elevated CPE mRNA expression was found in neuroendocrine tumors in lung and pituitary adenomas, although the significance is unclear since endocrine and neuroendocrine cells normally express CPE. However, studies of neuroendocrine tumors, pheochromocytomas, revealed expression of not only wild-type CPE, but a variant which was correlated with tumor behavior. Extremely high CPE mRNA copy numbers of the variant were found in very large or invasive tumors, both of which usually indicate poor prognosis. Thus, collectively the data suggest that CPE may play a role in promoting tumor growth and invasion. CPE could potentially serve as a diagnostic and prognostic biomarker for metastasis in different cancer types.
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Elias S, Delestre C, Courel M, Anouar Y, Montero-Hadjadje M. Chromogranin A as a crucial factor in the sorting of peptide hormones to secretory granules. Cell Mol Neurobiol 2010; 30:1189-95. [PMID: 21046450 DOI: 10.1007/s10571-010-9595-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 09/02/2010] [Indexed: 12/14/2022]
Abstract
Chromogranin A (CgA) is a soluble glycoprotein stored along with hormones and neuropeptides in secretory granules of endocrine cells. In the last four decades, intense efforts have been concentrated to characterize the structure and the biological function of CgA. Besides, CgA has been widely used as a diagnostic marker for tumors of endocrine origin, essential hypertension, various inflammatory diseases, and neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer's disease. CgA displays peculiar structural features, including numerous multibasic cleavage sites for prohormone convertases as well as a high proportion of acidic residues. Thus, it has been proposed that CgA represents a precursor of biologically active peptides, and a "granulogenic protein" that plays an important role as a chaperone for catecholamine storage in adrenal chromaffin cells. The widespread distribution of CgA throughout the neuroendocrine system prompted several groups to investigate the role of CgA in peptide hormone sorting to the regulated secretory pathway. This review summarizes the findings and theoretical concepts around the molecular machinery used by CgA to exert this putative intracellular function. Since CgA terminal regions exhibited strong sequence conservation through evolution, our work focused on the implication of these domains as potential functional determinants of CgA. Characterization of the molecular signals implicating CgA in the intracellular traffic of hormones represents a major biological issue that may contribute to unraveling the mechanisms defining the secretory competence of neuroendocrine cells.
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Affiliation(s)
- Salah Elias
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, INSERM U982, University of Rouen, Mont-St-Aignan Cedex, France
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NOS1AP regulates dendrite patterning of hippocampal neurons through a carboxypeptidase E-mediated pathway. J Neurosci 2009; 29:8248-58. [PMID: 19553464 DOI: 10.1523/jneurosci.5287-08.2009] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
During neuronal development, neurons form elaborate dendritic arbors that receive signals from axons. Additional studies are needed to elucidate the factors regulating the establishment of dendritic patterns. Our work explored possible roles played by nitric oxide synthase 1 adaptor protein (NOS1AP; also known as C-terminal PDZ ligand of neuronal nitric oxide synthase or CAPON) in dendritic patterning of cultured hippocampal neurons. Here we report that the long isoform of NOS1AP (NOS1AP-L) plays a novel role in regulating dendrite outgrowth and branching. NOS1AP-L decreases dendrite number when overexpressed at any interval between day in vitro (DIV) 0 and DIV 12, and knockdown of NOS1AP-L results in increased dendrite number. In contrast, the short isoform of NOS1AP (NOS1AP-S) decreases dendrite number only when overexpressed during DIV 5-7. Using mutants of NOS1AP-L, we show that neither the PDZ-binding domain nor the PTB domain is necessary for the effects of NOS1AP-L. We have functionally narrowed the region of NOS1AP-L that mediates this effect to the middle amino acids 181-307, a region that is not present in NOS1AP-S. Furthermore, we performed a yeast two-hybrid screen and identified carboxypeptidase E (CPE) as a binding partner for the middle region of NOS1AP-L. Biochemical and cellular studies reveal that CPE mediates the effects of NOS1AP on dendrite morphology. Together, our results suggest that NOS1AP-L plays an important role in the initiation, outgrowth, and maintenance of dendrites during development.
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Abstract
Insulin, the major secreted product of the beta-cells of the islets of Langerhans, is initially synthesized as a precursor (preproinsulin), from which the mature hormone is excised by a series of proteolytic cleavages. This review provides a personal narrative of some of the key research projects leading to the identification of the central processing enzymes as proprotein convertase 1, proprotein convertase 2, and carboxypeptidase E. It also discusses the central roles of the intragranular environment and chaperone-like proteins in modulating processing activity.
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Affiliation(s)
- Howard W Davidson
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Denver, CO, USA.
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29
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Abstract
Exocrine, endocrine, and neuroendocrine cells store hormones and neuropeptides in secretory granules (SGs), which undergo regulated exocytosis in response to an appropriate stimulus. These cargo proteins are sorted at the trans-Golgi network into forming immature secretory granules (ISGs). ISGs undergo maturation while they are transported to and within the F-actin-rich cortex. This process includes homotypic fusion of ISGs, acidification of their lumen, processing, and aggregation of cargo proteins as well as removal of excess membrane and missorted cargo. The resulting mature secretory granules (MSGs) are stored in the F-actin-rich cell cortex, perhaps as segregated pools exhibiting specific responses to stimuli for regulated exocytosis. During the last decade our understanding of the maturation of ISGs advanced substantially. The use of biochemical approaches led to the identification of membrane molecules mechanistically involved in this process. Furthermore, live cell imaging in combination with fluorescently tagged marker proteins of SGs provided insights into the dynamics of maturing ISGs, and the functional implications of cytoskeletal elements and motor proteins.
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Abstract
Animal obesity models differ widely in type and extent of obesity. They are either based on environmental factors (e.g., high-fat diet-induced obesity), spontaneous mutants (i.e., ob/ob mice), genetically engineered animals (e.g., mice with melanocortin receptor subtype-4 gene disruption (knock-out), or mechanical intervention (e.g., chemical lesion of the ventromedial hypothalamus). This unit reviews available rodent models to study obesity and attempts to highlight the greatest utility for each model.
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Courel M, Vasquez MS, Hook VY, Mahata SK, Taupenot L. Sorting of the neuroendocrine secretory protein Secretogranin II into the regulated secretory pathway: role of N- and C-terminal alpha-helical domains. J Biol Chem 2008; 283:11807-22. [PMID: 18299326 DOI: 10.1074/jbc.m709832200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Secretogranin II (SgII) belongs to the granin family of prohormones widely distributed in dense-core secretory granules (DCGs) of endocrine, neuroendocrine, and neuronal cells, including sympathoadrenal chromaffin cells. The mechanisms by which secretory proteins, and granins in particular, are sorted into the regulated secretory pathway are unsettled. We designed a strategy based on novel chimeric forms of human SgII fused to fluorescent (green fluorescent protein) or chemiluminescent (embryonic alkaline phosphatase) reporters to identify trafficking determinants mediating DCG targeting of SgII in sympathoadrenal cells. Three-dimensional deconvolution fluorescence microscopy and secretagogue-stimulated release studies demonstrate that SgII chimeras are correctly targeted to DCGs and released by exocytosis in PC12 and primary chromaffin cells. Results from a Golgi-retained mutant form of SgII suggest that sorting of SgII into DCGs depends on a saturable sorting machinery at the trans-Golgi/trans-Golgi network. Truncation analyses reveal the presence of DCG-targeting signals within both the N- and C-terminal regions of SgII, with the putative alpha-helix-containing SgII-(25-41) and SgII-(334-348) acting as sufficient, independent sorting domains. This study defines sequence features of SgII mediating vesicular targeting in sympathoadrenal cells and suggests a mechanism by which discrete domains of the molecule function in sorting, perhaps by virtue of a particular arrangement in tertiary structure and/or interaction with a specific component of the DCG membrane.
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Affiliation(s)
- Maïté Courel
- Department of Medicine, University of California at San Diego, La Jolla, California 92093-0838, USA
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Bogan RL, Murphy MJ, Stouffer RL, Hennebold JD. Systematic determination of differential gene expression in the primate corpus luteum during the luteal phase of the menstrual cycle. Mol Endocrinol 2008; 22:1260-73. [PMID: 18258683 DOI: 10.1210/me.2007-0484] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The molecular and cellular processes required for development, function, and regression of the primate corpus luteum (CL) are poorly defined. We hypothesized that there are dynamic changes in gene expression occurring during the CL life span, which represent proteins and pathways critical to its regulation. Therefore, a genomic approach was utilized to systematically identify differentially expressed genes in the rhesus macaque CL during the luteal phase of natural menstrual cycles. CL were collected between d 3-5 (early stage), d 7-8 (mid), d 10-12 (mid-late), d 14-16 (late), or d 18-19 (very-late) after the midcycle LH surge. From the early through very-late stages, 3234 transcripts were differentially expressed, with 879 occurring from the early through late stages that encompass the processes of luteinization, maintenance, and functional regression. To characterize gene changes most relevant to these processes, ontology analysis was performed using the list of 879 differentially expressed transcripts. Four main groups of related genes were identified with relevance to luteal physiology including: 1) immune function; 2) hormone and growth factor signaling; 3) steroidogenesis; and 4) prostaglandin biosynthesis, metabolism, and signaling. A subset of genes representing each of the four major categories was selected for validation of microarray results by quantitative real-time PCR. Results in mRNA levels were similar between the two methodologies for 17 of 18 genes. Additionally, protein levels for three genes were determined by Western blot analysis to parallel mRNA levels. This database will facilitate the identification of many novel or previously underappreciated pathways that regulate the structure and function of the primate CL.
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Affiliation(s)
- Randy L Bogan
- Division of Reproductive Sciences, Oregon National Primate Research Center, Oregon Health and Science University West Campus, Beaverton, Oregon 97006, USA
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33
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Dikeakos JD, Reudelhuber TL. Sending proteins to dense core secretory granules: still a lot to sort out. ACTA ACUST UNITED AC 2007; 177:191-6. [PMID: 17438078 PMCID: PMC2064127 DOI: 10.1083/jcb.200701024] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intracellular sorting of peptide hormone precursors to the dense core secretory granules (DCSGs) is essential for their bioactivation. Despite the fundamental importance of this cellular process, the nature of the sorting signals for entry of proteins into DCSGs remains a source of vigorous debate. This review highlights recent discoveries that are consistent with a model in which several protein domains, acting in a cell-specific fashion and at different steps in the sorting process, act in concert to regulate the entry of proteins into DCSGs.
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Affiliation(s)
- Jimmy D Dikeakos
- Laboratory of Molecular Biochemistry of Hypertension, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
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34
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Dikeakos JD, Lacombe MJ, Mercure C, Mireuta M, Reudelhuber TL. A hydrophobic patch in a charged alpha-helix is sufficient to target proteins to dense core secretory granules. J Biol Chem 2006; 282:1136-43. [PMID: 17092937 DOI: 10.1074/jbc.m605718200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many endocrine and neuroendocrine cells contain specialized secretory organelles called dense core secretory granules. These organelles are the repository of proteins and peptides that are secreted in a regulated manner when the cell receives a physiological stimulus. The targeting of proteins to these secretory granules is crucial for the generation of certain peptide hormones, including insulin and ACTH. Although previous work has demonstrated that proteins destined to a variety of cellular locations, including secretory granules, contain targeting sequences, no single consensus sequence for secretory granule-sorting signals has emerged. We have shown previously that alpha-helical domains in the C-terminal tail of the prohormone convertase PC1/3 play an important role in the ability of this region of the protein to direct secretory granule targeting (Jutras, I. Seidah, N. G., and Reudelhuber, T. L. (2000) J. Biol. Chem. 275, 40337-40343). In this study, we show that a variety of alpha-helical domains are capable of directing a heterologous secretory protein to granules. By testing a series of synthetic alpha-helices, we also demonstrate that the presence of charged (either positive or negative) amino acids spatially segregated from a hydrophobic patch in the alpha-helices of secretory proteins likely plays a critical role in the ability of these structures to direct secretory granule sorting.
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Affiliation(s)
- Jimmy D Dikeakos
- Laboratory of Molecular Biochemistry of Hypertension, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
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35
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Mulcahy LR, Vaslet CA, Nillni EA. Prohormone-convertase 1 processing enhances post-Golgi sorting of prothyrotropin-releasing hormone-derived peptides. J Biol Chem 2005; 280:39818-26. [PMID: 16204236 DOI: 10.1074/jbc.m507193200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rat prothyrotropin-releasing hormone (pro-TRH) is endoproteolyzed within the regulated secretory pathway of neuroendocrine cells yielding five TRH peptides and seven to nine other unique peptides. Endoproteolysis is performed by two prohormone convertases, PC1 and PC2. Proteolysis of pro-TRH begins in the trans-Golgi network and forms two intermediates that are then differentially processed as they exit the Golgi and are packaged into immature secretory granules. We hypothesized that this initial endoproteolysis may be necessary for downstream sorting of pro-TRH-derived peptides as it occurs before Golgi exit and thus entry into the regulated secretory pathway. We now report that when pro-TRH is transiently expressed in GH4C1 cells, a neuroendocrine cell line lacking PC1, under pulse-chase conditions release is constitutive and composed of more immature processing intermediates. This is also observed by radioimmunoassay under steady-state conditions. When a mutant form of pro-TRH, which has the dibasic sites of initial processing mutated to glycines, is expressed in AtT20 cells, a neuroendocrine cell line endogenously expressing PC1, both steady-state and pulse-chase experiments revealed that peptides derived from this mutant precursor are secreted in a constitutive fashion. A constitutively secreted form of PC1 does not target pro-TRH peptides to the constitutive secretory pathway but results in sorting to the regulated secretory pathway. These results indicated that initial processing action of PC1 on pro-TRH in the trans-Golgi network, and not a cargo-receptor relationship, is important for the downstream sorting events that result in storage of pro-TRH-derived peptides in mature secretory granules.
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Affiliation(s)
- Lawrence R Mulcahy
- Department of Medicine, Division of Endocrinology, Brown University Medical School, Rhode Island Hospital, Providence, Rhode Island 02903, USA
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36
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Lacombe MJ, Mercure C, Dikeakos JD, Reudelhuber TL. Modulation of Secretory Granule-targeting Efficiency by Cis and Trans Compounding of Sorting Signals. J Biol Chem 2005; 280:4803-7. [PMID: 15569678 DOI: 10.1074/jbc.m408658200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several protein domains acting through seemingly different mechanisms have been reported to have the capacity to target proteins to dense core secretory granules. Because proteins enter secretory granules with different efficiencies and because some of these proteins contain more than one granule-targeting motif, we have investigated whether compounding sorting signals could alter the efficiency of protein entry into secretory granules. In the current study we demonstrate that a paired basic cleavage site from human prorenin and an alpha-helix-containing secretory granule-sorting signal from the prohormone convertase PC1/3 can synergize to increase granule-sorting efficiency not only when located on the same protein, but also when located on distinct proteins that associate in the secretory pathway.
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Affiliation(s)
- Marie-Josée Lacombe
- Laboratory of Molecular Biochemistry of Hypertension, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
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Lou H, Kim SK, Zaitsev E, Snell CR, Lu B, Loh YP. Sorting and Activity-Dependent Secretion of BDNF Require Interaction of a Specific Motif with the Sorting Receptor Carboxypeptidase E. Neuron 2005; 45:245-55. [PMID: 15664176 DOI: 10.1016/j.neuron.2004.12.037] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 10/15/2004] [Accepted: 11/22/2004] [Indexed: 01/19/2023]
Abstract
Activity-dependent secretion of BDNF is important in mediating synaptic plasticity, but how it is achieved is unclear. Here we uncover a sorting motif receptor-mediated mechanism for regulated secretion of BDNF. X-ray crystal structure analysis revealed a putative sorting motif, I(16)E(18)I(105)D(106), in BDNF, which when mutated at the acidic residues resulted in missorting of proBDNF to the constitutive pathway in AtT-20 cells. A V20E mutation to complete a similar motif in NGF redirected a significant proportion of it from the constitutive to the regulated pathway. Modeling and binding studies showed interaction of the acidic residues in the BDNF motif with two basic residues in the sorting receptor, carboxypeptidase E (CPE). (35)S labeling experiments demonstrated that activity-dependent secretion of BDNF from cortical neurons was obliterated in CPE knockout mice. Thus, we have identified a mechanism whereby a specific motif I(16)E(18)I(105)D(106) interacts with CPE to sort proBDNF into regulated pathway vesicles for activity-dependent secretion.
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Affiliation(s)
- Hong Lou
- Section on Cellular Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Bundgaard JR, Birkedal H, Rehfeld JF. Progastrin Is Directed to the Regulated Secretory Pathway by Synergistically Acting Basic and Acidic Motifs. J Biol Chem 2004; 279:5488-93. [PMID: 14660571 DOI: 10.1074/jbc.m310547200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bioactivation of prohormones occurs in the granules of the regulated secretory pathway of endocrine cells, which release hormones in response to external stimulation. How secretory granules are formed and how the cargo is selected is still unclear, but it has been shown for several prohormones and processing enzymes that domains within the prohormone structure can act as "sorting signals" for this pathway. The domains mediate interactions with other proteins or with the membrane or facilitate aggregation of the (pro)peptides. We have now searched for domains in progastrin that are active in sorting the prohormone into secretory granules. Truncation studies showed that the N-terminal 30 residues of progastrin are dispensable, whereas the last 49 residues are sufficient for correct biosynthesis of bioactive gastrin. Thus, further N-terminal truncation abolished gastrin expression. C-terminal truncation of 8 residues resulted in an increase in basal secretion as did point mutations in the dibasic processing sites of progastrin. These mutants, however, still responded to secretagogues, suggesting a residual sorting capacity to the regulated pathway. Amino acid substitutions in an acidic, polyglutamate motif within gastrin-17, the main bioactive, cellular gastrin form, did not alter secretion per se, but when these residues were substituted in C-terminally truncated mutants, double mutants increased in basal secretion and did not respond to secretagogue stimulation. This implies that the mutants are constitutively secreted. Our data suggest that the dibasic processing sites constitute the most important sorting domain of progastrin, and these sites act in synergy with the acidic domain.
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Affiliation(s)
- Jens R Bundgaard
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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39
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Davidson HW. (Pro)Insulin processing. Cell Biochem Biophys 2004. [DOI: 10.1007/bf02739019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Dhanvantari S, Shen FS, Adams T, Snell CR, Zhang C, Mackin RB, Morris SJ, Loh YP. Disruption of a receptor-mediated mechanism for intracellular sorting of proinsulin in familial hyperproinsulinemia. Mol Endocrinol 2003; 17:1856-67. [PMID: 12829804 DOI: 10.1210/me.2002-0380] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In familial hyperproinsulinemia, specific mutations in the proinsulin gene are linked with a profound increase in circulating plasma proinsulin levels. However, the molecular and cellular basis for this disease remains uncharacterized. Here we investigated how these mutations may disrupt the sorting signal required to target proinsulin to the secretory granules of the regulated secretory pathway, resulting in the unregulated release of proinsulin. Using a combination of molecular modeling and site-directed mutagenesis, we have identified structural molecular motifs in proinsulin that are necessary for correct sorting into secretory granules of endocrine cells. We show that membrane carboxypeptidase E (CPE), previously identified as a prohormone-sorting receptor, is essential for proinsulin sorting. This was demonstrated through short interfering RNA-mediated depletion of CPE and transfection with a dominant negative mutant of CPE in a beta-cell line. Mutant proinsulins found in familial hyperproinsulinemia failed to bind to CPE and were not sorted efficiently. These findings provide evidence that the elevation of plasma proinsulin levels found in patients with familial hyperproinsulinemia is caused by the disruption of CPE-mediated sorting of mutant proinsulins to the regulated secretory pathway.
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Affiliation(s)
- Savita Dhanvantari
- Section on Cellular Neurobiology, National Institutes of Health, Bethesda, Maryland 20892-4480, USA
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Sasson R, Dantes A, Tajima K, Amsterdam A. Novel genes modulated by FSH in normal and immortalized FSH-responsive cells: new insights into the mechanism of FSH action. FASEB J 2003; 17:1256-66. [PMID: 12832290 DOI: 10.1096/fj.02-0740com] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Follicle-stimulating hormone (FSH) controls the development of follicle-enclosed oocytes in the mammalian ovary by interacting with specific receptors located exclusively on granulosa cells. Its biological activity involves stimulation of intercellular communication, intracellular signaling, and up-regulation of steroidogenesis; the entire spectrum of genes regulated by FSH is not yet fully characterized. We have established monoclonal rat FSH-responsive granulosa cell lines that express FSH receptors at 20-fold higher rates than with primary cells, and thus increased the probability of yielding a distinct spectrum of genes modulated by FSH. Using Affymetrix DNA microarrays, we discovered 11 genes not reported earlier to be up-regulated by FSH and 9 genes not reported earlier to be down-regulated by FSH. Modulation of signal transduction associated with G-protein signaling, phosphorylation of proteins, and intracellular-extracellular ion balance was suggested by up-regulation of decay accelerating factor GPI-form precursor (DAF), membrane interacting protein RGS16, protein tyrosine phosphatase (PTPase), oxidative stress-inducible protein tyrosine phosphatase (OSIPTPase), and down-regulation of rat prostatic acid phosphatase (rPAP), Na+, K+-ATPase, and protein phosphatase 1beta. Elevation in granzyme-like proteins 1 and 3, and natural killer (NK) cell protease 1 (NKP-1) along with reduction in carboxypeptidase E indicates possible FSH-mediated preparation of the cells for apoptosis. Up-regulation of vascular endothelial growth factors indicates the ability of FSH to produce angiogenic factors upon their maturation; whereas, reduction in insulin-like growth factor binding protein (IGFBP3) indicates its increased potential to promote p53-induced apoptosis. Striking similarities in FSH modulation of gene expression were found in primary cultures of human granulosa cells obtained from IVF patients although these cells expressed only 1% of FSH receptor compared with immortalized rat cells, as indicated by microarray technique, which probably is in the normal range of expression of this receptor in nontransformed cells. These findings should increase our understanding of the mechanism of FSH action in stimulating development of the ovarian follicular cells, of intracellular and intercellular communication, and of increasing the potential of ovarian follicular cells to undergo apoptosis during the process of selection of the dominant follicle.
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Affiliation(s)
- Ravid Sasson
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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42
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Cawley NX, Rodriguez YM, Maldonado A, Loh YP. Trafficking of mutant carboxypeptidase E to secretory granules in a beta-cell line derived from Cpe(fat)/Cpe(fat) mice. Endocrinology 2003; 144:292-8. [PMID: 12488357 DOI: 10.1210/en.2002-220588] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have reinvestigated the stability and intracellular routing of mutant carboxypeptidase E in NIT3 cells, a pancreatic beta-cell line derived from the Cpe(fat)/Cpe(fat) mouse. Pulse-chase experiments demonstrated that this protein has a half-life of approximately 3 h in these cells and that up to 45% of the proCPE(202) can escape degradation by the proteosome. In double-label immunofluorescence microscopy, a portion of the mutant CPE did not colocalize with calnexin, an endoplasmic reticulum marker, but was found in prohormone convertase 2-containing secretory granules, demonstrating that it had escaped degradation and arrived at a post-Golgi compartment. The mutant CPE as well as prohormone convertase 2 were secreted into the medium in a stimulated manner by treatment with the physiological secretagogue, glucagon-like peptide-1, consistent with its presence in granules of the regulated secretory pathway. The presence of mutant carboxypeptidase E in granules supports a potential role for its involvement as a sorting/retention receptor in the trafficking of proinsulin to the regulated secretory pathway.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular Neurobiology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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Jain RK, Chang WT, Geetha C, Joyce PBM, Gorr SU. In vitro aggregation of the regulated secretory protein chromogranin A. Biochem J 2002; 368:605-10. [PMID: 12175332 PMCID: PMC1222998 DOI: 10.1042/bj20021195] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2002] [Revised: 08/08/2002] [Accepted: 08/13/2002] [Indexed: 11/17/2022]
Abstract
Aggregation chaperones, consisting of secretory proteins that contain a hexa-histidine epitope tag, enhance the calcium-induced aggregation of regulated secretory proteins and their sorting to secretory granules. The goal of this study was to gain a better understanding of this unusual aggregation mechanism. Hexa-histidine-epitope-tagged secreted alkaline phosphatase, an aggregation chaperone, enhanced the in vitro aggregation of chromogranin A in the presence of calcium, but not in the presence of magnesium or other divalent cations. As an exception, chromogranin was completely aggregated by zinc, even in the absence of the aggregation chaperone. In addition, fluorescence spectroscopy of the aggregation reaction mixture showed an increase in fluorescence intensity consistent with the formation of protein aggregates. The calcium-induced aggregation of chromogranin A was completely inhibited by 0.2% Triton X-100, suggesting that it involves hydrophobic interactions. In contrast, the detergent did not affect chaperone-enhanced aggregation, suggesting that this aggregation does not depend on hydrophobic interactions. EDTA-treated chaperone did not enhance chromogranin A aggregation, indicating that divalent cations are necessary for chaperone action. Although the structure of the aggregation chaperone was not important, the size of the chaperone was. Thus the free His-hexapeptide could not substitute for the aggregation chaperone. Based on these results, we propose that the hexa-histidine tag, in the context of a polypeptide, acts as a divalent cation-dependent nucleation site for chromogranin A aggregation.
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Affiliation(s)
- Renu K Jain
- Department of Periodontics, Endodontics and Dental Hygiene, Health Sciences Center, University of Louisville, Louisville, KY 40292, U.S.A
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Fan X, Olson SJ, Blevins LS, Allen GS, Johnson MD. Immunohistochemical localization of carboxypeptidases D, E, and Z in pituitary adenomas and normal human pituitary. J Histochem Cytochem 2002; 50:1509-16. [PMID: 12417617 DOI: 10.1177/002215540205001111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Carboxypeptidases may play important role(s) in prohormone processing in normal and neoplastic adenohypophyseal cells of the pituitary. We have recently demonstrated carboxypeptidase E (CPE) and carboxypeptidase Z (CPZ) in the majority of adenohypophyseal cells with carboxypeptidase D (CPD) immunoreactivity largely confined to adrenocorticotrophs. This study evaluated the expression patterns of CPE, CPD, and CPZ immunoreactivity in 48 pituitary adenomas. Our immunohistochemistry demonstrated extensive intracytoplasmic immunoreactivity for CPE, CPD, and CPZ in adrenocorticotrophic hormone (ACTH)-producing adrenocorticotroph cells, prolactin-producing lactotroph cells, and growth hormone (GH)-producing somatotroph cell adenomas, all of which require carboxypeptide processing of prohormones to produce active endocrine hormones. In contrast to the restricted expression in the normal adenohypophysis, CPD appeared to be widespread in the majority of adenomas, suggesting that CPD levels are increased in adenomas. In luteinizing hormone/follicle-stimulating hormone (LH/FSH)-producing gonadotroph adenomas, which do not require carboxypeptidases to produce gonadotropins, only CPZ immunostaining was demonstrated. In null-cell adenomas, CPE immunoreactivity was detected in the majority of tumors, but CPD and CPZ were identified only in a minority of cases. CPE in these cells may process other peptides critical for pituitary cell function, such as chromogranin A or B. These findings suggest that CPs participate in the functioning of pituitary adenomas.
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Affiliation(s)
- Xuemo Fan
- Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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Loh YP, Maldonado A, Zhang C, Tam WH, Cawley N. Mechanism of sorting proopiomelanocortin and proenkephalin to the regulated secretory pathway of neuroendocrine cells. Ann N Y Acad Sci 2002; 971:416-25. [PMID: 12438160 DOI: 10.1111/j.1749-6632.2002.tb04504.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Proopiomelanocortin (POMC) and proenkephalin (PE) are synthesized at the endoplasmic reticulum and transported to the trans-Golgi network (TGN) where they are sorted and packaged into dense-core granules of the regulated secretory pathway (RSP). The mechanism of sorting POMC and PE to the RSP in neuroendocrine cells was investigated. Consensus sorting signals comprising two acidic residues and two hydrophobic residues exposed on the surface of N-POMC(1-26) and N-PE(1-32) were identified and shown to be sufficient and necessary for targeting POMC and PE to the RSP in PC12, Neuro2a, and AtT-20 cells. The acidic residues of these sorting signals bind specifically to basic residues on the sorting receptor membrane, carboxypeptidase E (CPE), to effect sorting to the RSP. Analysis of POMC and PE sorting in Neuro2a cells depleted of CPE by CPE antisense RNA, and Cpe(fat/fat) mouse pituitary cells lacking CPE showed missorting of both these molecules to the constitutive pathway in vivo. Thus, POMC and PE are sorted to the RSP at the TGN by a mechanism involving the interaction of a specific sorting signal on these molecules with the sorting receptor, CPE.
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Affiliation(s)
- Y Peng Loh
- Section on Cellular Neurobiology, Laboratory of Developmental Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Abstract
OBJECTIVE To evaluate the opportunities afforded cardiovascular medicine by the comprehensive and integrative approaches of genomics in cellular physiology. We present a meta-analysis of recently reported results obtained by means of high-throughput technologies (complementary DNA and oligonucleotide arrays, serial analysis of gene expression [SAGE]), as well as more traditional molecular biology approaches (real-time polymerase chain reaction, differential display, and others). DATA SOURCES Newly published articles identified on PubMed and additional data provided by authors on-line (where available). CONCLUSIONS The impact of genomic analysis on cardiovascular research is already visible. New genes of cardiovascular interest have been discovered, while a number of known genes have been found to be changed in unexpected contexts. The patterns in the variation of expression of many genes correlate well with the models currently used to explain the pathogenesis of cardiovascular diseases. Much more work has yet to be done, however, for the full exploitation of the immense informative potential still dormant in the genomic technologies.
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Affiliation(s)
- Leni Moldovan
- Dorothy M. Davis Heart and Lung Research Institute and Division of Cardiology, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
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Rao S, Lang C, Levitan ES, Deitcher DL. Visualization of neuropeptide expression, transport, and exocytosis in Drosophila melanogaster. JOURNAL OF NEUROBIOLOGY 2001; 49:159-72. [PMID: 11745655 DOI: 10.1002/neu.1072] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Neuropeptides affect an extremely diverse set of physiological processes. Neuropeptides are often coreleased with neurotransmitters but, unlike neurotransmitters, the neuropeptide target cells may be distant from the site(s) of secretion. Thus, it is often difficult to measure the amount of neuropeptide release in vivo by electrophysiological methods. Here we establish an in vivo system for studying the developmental expression, processing, transport, and release of neuropeptides. A GFP-tagged atrial natriuretic factor fusion (preproANF-EMD) was expressed in the Drosophila nervous system with the panneural promoter, elav. During embryonic development, proANF-EMD was first seen to accumulate in synaptic regions of the CNS in stage 17 embryos. By the third instar larval stage, highly fluorescent neurons were evident throughout the CNS. In the adult, fluorescence was pronounced in the mushroom bodies, antennal lobe, and the central complex. At the larval neuromuscular junction, proANF-EMD was concentrated in nerve terminals. We compared the release of proANF-EMD from synaptic boutons of NMJ 6/7, which contain almost exclusively glutamate-containing clear vesicles, to those of NMJ 12, which include the peptidergic type III boutons. Upon depolarization, approximately 60% of the tagged neuropeptide was released from NMJs of both muscles in 15 min, as assayed by decreased fluorescence. Although the elav promoter was equally active in the motor neurons that innervate both NMJs 6/7 and 12, NMJ 12 contained 46-fold more neuropeptide and released much more proANF-EMD during stimulation than did NMJ 6/7. Our results suggest that peptidergic neurons have an enhanced ability to accumulate and/or release neuropeptides as compared to neurons that primarily release classical neurotransmitters.
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Affiliation(s)
- S Rao
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
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Abstract
The trans-Golgi network (TGN) is a major secretory pathway sorting station that directs newly synthesized proteins to different subcellular destinations. The TGN also receives extracellular materials and recycled molecules from endocytic compartments. In this review, we summarize recent progress on understanding TGN structure and the dynamics of trafficking to and from this compartment. Protein sorting into different transport vesicles requires specific interactions between sorting motifs on the cargo molecules and vesicle coat components that recognize these motifs. Current understanding of the various targeting signals and vesicle coat components that are involved in TGN sorting are discussed, as well as the molecules that participate in retrieval to this compartment in both yeast and mammalian cells. Besides proteins, lipids and lipid-modifying enzymes also participate actively in the formation of secretory vesicles. The possible mechanisms of action of these lipid hydrolases and lipid kinases are discussed. Finally, we summarize the fundamentally different apical and basolateral cell surface delivery mechanisms and the current facts and hypotheses on protein sorting from the TGN into the regulated secretory pathway in neuroendocrine cells.
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Affiliation(s)
- F. Gu
- Vollum Institute, L-474, Oregon Health Science University, 3181 SW Sam Jackson Park Road, Portland (Oregon 97201, USA), Fax: +1 503 494 4534, e-mail: , , , , US
| | - C.M. Crump
- Vollum Institute, L-474, Oregon Health Science University, 3181 SW Sam Jackson Park Road, Portland (Oregon 97201, USA), Fax: +1 503 494 4534, e-mail: , , , , US
| | - G. Thomas
- Vollum Institute, L-474, Oregon Health Science University, 3181 SW Sam Jackson Park Road, Portland (Oregon 97201, USA), Fax: +1 503 494 4534, e-mail: , , , , US
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Zhang BY, Chang A, Kjeldsen TB, Arvan P. Intracellular retention of newly synthesized insulin in yeast is caused by endoproteolytic processing in the Golgi complex. J Cell Biol 2001; 153:1187-98. [PMID: 11402063 PMCID: PMC2192022 DOI: 10.1083/jcb.153.6.1187] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An insulin-containing fusion protein (ICFP, encoding the yeast prepro-alpha factor leader peptide fused via a lysine-arginine cleavage site to a single chain insulin) has been expressed in Saccharomyces cerevisiae where it is inefficiently secreted. Single gene disruptions have been identified that cause enhanced immunoreactive insulin secretion (eis). Five out of six eis mutants prove to be vacuolar protein sorting (vps)8, vps35, vps13, vps4, and vps36, which affect Golgi<-->endosome trafficking. Indeed, in wild-type yeast insulin is ultimately delivered to the vacuole, whereas vps mutants secrete primarily unprocessed ICFP. Disruption of KEX2, which blocks intracellular processing to insulin, quantitatively reroutes ICFP to the cell surface, whereas loss of the Vps10p sorting receptor is without effect. Secretion of unprocessed ICFP is not based on a dominant secretion signal in the alpha-leader peptide. Although insulin sorting mediated by Kex2p is saturable, Kex2p functions not as a sorting receptor but as a protease: replacement of Kex2p by truncated secretory Kex2p (which travels from Golgi to cell surface) still causes endoproteolytic processing and intracellular insulin retention. Endoproteolysis promotes a change in insulin's biophysical properties. B5His residues normally participate in multimeric insulin packing; a point mutation at this position permits ICFP processing but causes the majority of processed insulin to be secreted. The data argue that multimeric assembly consequent to endoproteolytic maturation regulates insulin sorting in the secretory pathway.
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Affiliation(s)
- Bao-yan Zhang
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Amy Chang
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461
| | | | - Peter Arvan
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
- Division of Endocrinology, Albert Einstein College of Medicine, Bronx, New York 10461
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Dhanvantari S, Loh YP. Lipid raft association of carboxypeptidase E is necessary for its function as a regulated secretory pathway sorting receptor. J Biol Chem 2000; 275:29887-93. [PMID: 10896946 DOI: 10.1074/jbc.m005364200] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane carboxypeptidase E (CPE) is a sorting receptor for targeting prohormones, such as pro-opiomelanocortin, to the regulated secretory pathway in endocrine cells. Its membrane association is necessary for it to bind a prohormone sorting signal at the trans-Golgi network (TGN) to facilitate targeting. In this study, we examined the lipid interaction of CPE in bovine pituitary secretory granule membranes, which are derived from the TGN. We show that CPE is associated with detergent-resistant lipid domains, or rafts, within secretory granule membranes. Lipid analysis revealed that these rafts are enriched in glycosphingolipids and cholesterol. Pulse-chase and subcellular fractionation experiments in AtT-20 cells show that the association of CPE with membrane rafts occurred only after it reached the Golgi. Cholesterol depletion resulted in dissociation of CPE from secretory granule membranes and decreased the binding of prohormones to membranes. In vivo cholesterol depletion using lovastatin resulted in the lack of sorting of CPE and its cargo to the regulated secretory pathway. We propose that the sorting receptor function of CPE necessitates its interaction with glycosphingolipid-cholesterol rafts at the TGN, thereby anchoring it in position to bind to its prohormone cargo.
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Affiliation(s)
- S Dhanvantari
- Section on Cellular Neurobiology, Laboratory of Developmental Neurobiology, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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