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Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Bartolomucci A, Possenti R, Mahata SK, Fischer-Colbrie R, Loh YP, Salton SRJ. The extended granin family: structure, function, and biomedical implications. Endocr Rev 2011; 32:755-97. [PMID: 21862681 PMCID: PMC3591675 DOI: 10.1210/er.2010-0027] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The chromogranins (chromogranin A and chromogranin B), secretogranins (secretogranin II and secretogranin III), and additional related proteins (7B2, NESP55, proSAAS, and VGF) that together comprise the granin family subserve essential roles in the regulated secretory pathway that is responsible for controlled delivery of peptides, hormones, neurotransmitters, and growth factors. Here we review the structure and function of granins and granin-derived peptides and expansive new genetic evidence, including recent single-nucleotide polymorphism mapping, genomic sequence comparisons, and analysis of transgenic and knockout mice, which together support an important and evolutionarily conserved role for these proteins in large dense-core vesicle biogenesis and regulated secretion. Recent data further indicate that their processed peptides function prominently in metabolic and glucose homeostasis, emotional behavior, pain pathways, and blood pressure modulation, suggesting future utility of granins and granin-derived peptides as novel disease biomarkers.
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Affiliation(s)
- Alessandro Bartolomucci
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Lawrence B, Gustafsson BI, Kidd M, Pavel M, Svejda B, Modlin IM. The clinical relevance of chromogranin A as a biomarker for gastroenteropancreatic neuroendocrine tumors. Endocrinol Metab Clin North Am 2011; 40:111-34, viii. [PMID: 21349414 DOI: 10.1016/j.ecl.2010.12.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chromogranin A, although it exhibits limitations, is currently the most useful general tumor biomarker available for use in the diagnosis and management of gastroenteropancreatic neuroendocrine tumors (NETs). The value of the chromogranin A lies in its universal cosecretion by the majority of neuroendocrine cells that persists after malignant transformation. Clinicians aware of the physiologic role of chromogranin A and its secretion in a variety of non-NET-related pathologic conditions can use this protein as a moderately effective tumor biomarker in the management of GEP-NETs.
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Affiliation(s)
- Ben Lawrence
- Gastrointestinal Pathobiology Research Group, Department of Surgery, Yale University School of Medicine, 310 Cedar Street, PO Box 208602, New Haven, CT 06520-8062, USA
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Regulation of the hypothalamic thyrotropin releasing hormone (TRH) neuron by neuronal and peripheral inputs. Front Neuroendocrinol 2010; 31:134-56. [PMID: 20074584 PMCID: PMC2849853 DOI: 10.1016/j.yfrne.2010.01.001] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 12/29/2009] [Accepted: 01/06/2010] [Indexed: 12/29/2022]
Abstract
The hypothalamic-pituitary-thyroid (HPT) axis plays a critical role in mediating changes in metabolism and thermogenesis. Thus, the central regulation of the thyroid axis by Thyrotropin Releasing Hormone (TRH) neurons in the paraventricular nucleus of the hypothalamus (PVN) is of key importance for the normal function of the axis under different physiological conditions including cold stress and changes in nutritional status. Before the TRH peptide becomes biologically active, a series of tightly regulated processes occur including the proper folding of the prohormone for targeting to the secretory pathway, its post-translational processing, and targeting of the processed peptides to the secretory granules near the plasma membrane of the cell ready for secretion. Multiple inputs coming from the periphery or from neurons present in different areas of the brain including the hypothalamus are responsible for the activation or inhibition of the TRH neuron and in turn affect the output of TRH and the set point of the axis.
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Modlin IM, Gustafsson BI, Moss SF, Pavel M, Tsolakis AV, Kidd M. Chromogranin A--biological function and clinical utility in neuro endocrine tumor disease. Ann Surg Oncol 2010; 17:2427-43. [PMID: 20217257 DOI: 10.1245/s10434-010-1006-3] [Citation(s) in RCA: 244] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Indexed: 02/06/2023]
Abstract
BACKGROUND Neuroendocrine tumors (NETs) are a form of cancer that differ from other neoplasia in that they synthesize, store, and secrete peptides, e.g., chromogranin A (CgA) and amines. A critical issue is late diagnosis due to failure to identify symptoms or to establish the biochemical diagnosis. We review here the utility of CgA measurement in NETs and describe its biological role and the clinical value of its measurement. METHODS Literature review and analysis of the utility of plasma/serum CgA measurements in NETs and other diseases. RESULTS CgA is a member of the chromogranin family; its transcription and peptide processing are well characterized, but its precise function remains unknown. Levels are detectable in the circulation but vary substantially (approximately 25%) depending on which assay is used. Serum and plasma measurements are concordant. CgA is elevated in approximately 90% of gut NETs and correlates with tumor burden and recurrence. Highest values are noted in ileal NETs and gastrointestinal NETs associated with multiple endocrine neoplasia type 1. Both functioning and nonfunctioning pancreatic NETs have elevated values. CgA is more frequently elevated in well-differentiated tumors compared to poorly differentiated NETs. Effective treatment is often associated with decrease in CgA levels. Proton pump inhibitors falsely increase CgA, but levels normalize with therapy cessation. CONCLUSIONS CgA is currently the best available biomarker for the diagnosis of NETs. It is critical to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy. Measurement of plasma CgA is mandatory for the effective diagnosis and management of NET disease.
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Affiliation(s)
- Irvin M Modlin
- Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, CT, USA.
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Hol J, Küchler AM, Johansen FE, Dalhus B, Haraldsen G, Oynebråten I. Molecular requirements for sorting of the chemokine interleukin-8/CXCL8 to endothelial Weibel-Palade bodies. J Biol Chem 2009; 284:23532-9. [PMID: 19578117 DOI: 10.1074/jbc.m900874200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sorting of proteins to Weibel-Palade bodies (WPB) of endothelial cells allows rapid regulated secretion of leukocyte-recruiting P-selectin and chemokines as well as procoagulant von Willebrand factor (VWF). Here we show by domain swap studies that the exposed aspartic acid in loop 2 (Ser(44)-Asp(45)-Gly(46)) of the CXC chemokine interleukin (IL)-8 is crucial for targeting to WPB. Loop 2 also governs sorting of chemokines to alpha-granules of platelets, but the fingerprint of the loop 2 of these chemokines differs from that of IL-8. On the other hand, loop 2 of IL-8 closely resembles a surface-exposed sequence of the VWF propeptide, the region of VWF that directs sorting of the protein to WPB. We conclude that loop 2 of IL-8 constitutes a critical signal for sorting to WPB and propose a general role for this loop in the sorting of chemokines to compartments of regulated secretion.
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Affiliation(s)
- Johanna Hol
- Institute and University of Oslo, Rikshospitalet University Hospital, Sognsvannsveien 20, 0027 Oslo, Norway
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Creemers JWM, Lee YS, Oliver RL, Bahceci M, Tuzcu A, Gokalp D, Keogh J, Herber S, White A, O'Rahilly S, Farooqi IS. Mutations in the amino-terminal region of proopiomelanocortin (POMC) in patients with early-onset obesity impair POMC sorting to the regulated secretory pathway. J Clin Endocrinol Metab 2008; 93:4494-9. [PMID: 18697863 DOI: 10.1210/jc.2008-0954] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Mutations in the proopiomelanocortin (POMC) gene that impair the synthesis or structure of POMC-derived peptides predispose to human obesity. OBJECTIVE Our objective was to identify and characterize novel mutations in the POMC gene found in patients with early-onset obesity. DESIGN AND PATIENTS The POMC gene was screened in 500 patients with severe early-onset obesity. The biosynthesis, processing, sorting, and secretion of wild-type POMC and two newly identified POMC mutants was studied using metabolic labeling, Western blotting, and immunoassay analysis of lysates and conditioned media of transiently transfected beta-TC3 cells. RESULTS Two novel heterozygous missense mutations in POMC (C28F and L37F) were identified in unrelated probands with early-onset obesity and their overweight or obese family members. Both mutations lie in a region of the N terminus of POMC that has been suggested to be involved in its sorting to the regulated secretory pathway. Metabolic labeling studies indicate that whereas the mutations do not reduce intracellular levels of POMC, both mutations (C28F>L37F) impair the ability of POMC to be processed to generate bioactive products. Studies of the secretion of POMC products suggest, particularly with C28F, that the impaired propeptide processing of these mutations results, at least in part, from a mistargeting of mutant POMC to the constitutive rather than the regulated secretory pathway. CONCLUSION These mutations in patients with early-onset obesity represent a novel molecular mechanism of human POMC deficiency whereby naturally occurring mutations in its N-terminal sequence impair the ability of POMC to enter the trafficking pathway in which serial propeptide processing normally occurs.
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Affiliation(s)
- John W M Creemers
- University of Leuven, Center for Human Genetics, B-3000 Leuven, Belgium.
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Chu C, Gao G, Huang W. Ischemia-reperfusion injury effects a change in expression of GnRH and its receptor in CA1 neurons in rat hippocampus. Int J Neurosci 2008; 118:375-90. [PMID: 18300011 DOI: 10.1080/00207450701392142] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Many researches on the change and protective effects of estrogen and its receptor in hippocampus with ischemia-reperfusion injury have been done in recent years; the study on the change of GnRH and its receptor in hippocampus with ischemia-reperfusion injury has not been seen yet. This study used immunohistochemistry and in situ hybridization method, together with an image analysis system to observe the change in expression of GnRH and its receptor in hippocampus with ischemia-reperfusion injury. The study found that the expression of GnRH and GnRH mRNA and the number of positive cells decreased with time after damage. Expression of GnRH receptor and GnRH receptor mRNA in single positive cell early increased and later decreased after injury; the number of positive cells decreased with time after injury. Three days after injury, rare GnRH, GnRHR immunoreactive positive cells and cells with GnRH mRNA, GnRHR mRNA hybridization signal could be found in the stratum pyramida of CA1 region, many cells with weak GnRH, GnRH receptor immunoreactivity and weak GnRH mRNA, GnRH receptor mRNA hybridization signal appeared at stratum oriens and stratum radiatum. These suggested that GnRH may participate in the regulation of ischemia-reperfusion injury in CA1 region and repair of brain tissue.
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Affiliation(s)
- Chenyu Chu
- Department of Neurosurgery, Tangdu Hospital, Fourth Military Medical University, Xi'an City, China
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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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Origins of the regulated secretory pathway. THE GOLGI APPARATUS 2008. [PMCID: PMC7121582 DOI: 10.1007/978-3-211-76310-0_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modes of transport of soluble (or luminal) secretory proteins synthesized in the endoplasmic reticulum (ER) could be divided into two groups. The socalled constitutive secretory pathway (CSP) is common to all eukaryotic cells, constantly delivering constitutive soluble secretory proteins (CSSPs) linked to the rate of protein synthesis but largely independent of external stimuli. In regulated secretion, protein is sorted from the Golgi into storage/secretory granules (SGs) whose contents are released when stimuli trigger their final fusion with the plasma membrane (Hannah et al. 1999).
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Venkatesh SG, Tan J, Gorr SU, Darling DS. Isoproterenol increases sorting of parotid gland cargo proteins to the basolateral pathway. Am J Physiol Cell Physiol 2007; 293:C558-65. [PMID: 17537806 PMCID: PMC2084485 DOI: 10.1152/ajpcell.00081.2007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exocrine cells have an essential function of sorting secreted proteins into the correct secretory pathway. A clear understanding of sorting in salivary glands would contribute to the correct targeting of therapeutic transgenes. The present work investigated whether there is a change in the relative proportions of basic proline-rich protein (PRP) and acidic PRPs in secretory granules in response to chronic isoproterenol treatment, and whether this alters the sorting of endogenous cargo proteins. Immunoblot analysis of secretory granules from rat parotids found a large increase of basic PRP over acidic PRPs in response to chronic isoproterenol treatment. Pulse chase experiments demonstrated that isoproterenol also decreased regulated secretion of newly synthesized secretory proteins, including PRPs, amylase and parotid secretory protein. This decreased efficiency of the apical regulated pathway may be mediated by alkalization of the secretory granules since it was reversed by treatment with mild acid. We also investigated changes in secretion through the basolateral (endocrine) pathways. A significant increase in parotid secretory protein and salivary amylase was detected in sera of isoproterenol-treated animals, suggesting increased routing of the regulated secretory proteins to the basolateral pathway. These studies demonstrate that shifts of endogenous proteins can modulate regulated secretion and sorting of cargo proteins.
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Affiliation(s)
| | | | | | - Douglas S. Darling
- Corresponding author: D.S. Darling, Department of Periodontics, Endodontics and Dental Hygiene, University of Louisville School of Dentistry, Room 209E, Louisville, Kentucky 40292 E-mail: , Phone: 502-852-5508, Fax: 502-852-1317
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Yan X, Voutetakis A, Zheng C, Hai B, Zhang C, Baum BJ, Wang S. Sorting of transgenic secretory proteins in miniature pig parotid glands following adenoviral-mediated gene transfer. J Gene Med 2007; 9:779-87. [PMID: 17654745 DOI: 10.1002/jgm.1081] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Gene transfer to salivary glands for use in treating both systemic and upper gastrointestinal tract diseases shows considerable potential. Numerous studies in rodents demonstrate that salivary glands can secrete transgenic secretory proteins either into saliva, primarily via the regulated secretory pathway (RSP), or into the bloodstream, primarily by the constitutive secretory pathway (CSP). The purpose of the present study was to assess the sorting characteristics of human growth hormone (hGH), a RSP protein, and human erythropoietin (hEpo), a CSP protein, in a large animal model of salivary gland gene transfer, the miniature pig. METHODS Recombinant serotype 5 adenoviral (Ad5; 10(11) particles/gland) vectors encoding either hGH (AdCMVhGH) or hEpo (AdCMVhEpo) were administered to both parotid glands of male miniature pigs by intraductal cannulation. The secretion of hGH or hEpo was measured in both saliva and serum on days 3, 7 and 14 following administration. Detailed serum chemistry and hematological analyses were performed, and the presence of serum antibodies to hGH and hEpo was measured. For AdCMVhEpo-treated minipigs vector distribution in multiple tissues was determined by quantitative polymerase chain reaction (QPCR). RESULTS The RSP protein hGH was secreted entirely into saliva, while the CSP protein hEpo was secreted into both saliva and serum. Most hEpo was found in saliva, but serum hEpo levels were sufficient to significantly increase hematocrit levels in treated animals by approximately 10%. Expression of both transgenes was maximal on day 3 and declined to near background by day 14. The amount of vector found in the targeted glands was 100 x more than in other tissues. CONCLUSIONS Secretion of transgenic hGH from minipig parotid glands occurred principally into saliva via the RSP, as seen in rodents, while hEpo was secreted into both saliva and serum, the latter presumably via the CSP. Even though hEpo secretion into the bloodstream was not to the extent previously observed in rodents, serum hEpo levels were considerable and the hEpo was biologically active. Ad5 vector distribution was highly restricted to the parotid glands with little vector detected elsewhere. While the results in this large animal model support the established notion that salivary gland gene transfer can be used for treating systemic single protein deficiency disorders, they also highlight differences in transgenic CSP protein sorting between rodents and miniature pigs.
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Affiliation(s)
- Xing Yan
- Salivary Gland Disease Center and the Molecular Laboratory for Gene Therapy, School of Stomatology, Capital Medical University, Beijing, PR China
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Sobota JA, Ferraro F, Bäck N, Eipper BA, Mains RE. Not all secretory granules are created equal: Partitioning of soluble content proteins. Mol Biol Cell 2006; 17:5038-52. [PMID: 17005911 PMCID: PMC1761688 DOI: 10.1091/mbc.e06-07-0626] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Secretory granules carrying fluorescent cargo proteins are widely used to study granule biogenesis, maturation, and regulated exocytosis. We fused the soluble secretory protein peptidylglycine alpha-hydroxylating monooxygenase (PHM) to green fluorescent protein (GFP) to study granule formation. When expressed in AtT-20 or GH3 cells, the PHM-GFP fusion protein partitioned from endogenous hormone (adrenocorticotropic hormone, growth hormone) into separate secretory granule pools. Both exogenous and endogenous granule proteins were stored and released in response to secretagogue. Importantly, we found that segregation of content proteins is not an artifact of overexpression nor peculiar to GFP-tagged proteins. Neither luminal acidification nor cholesterol-rich membrane microdomains play essential roles in soluble content protein segregation. Our data suggest that intrinsic biophysical properties of cargo proteins govern their differential sorting, with segregation occurring during the process of granule maturation. Proteins that can self-aggregate are likely to partition into separate granules, which can accommodate only a few thousand copies of any content protein; proteins that lack tertiary structure are more likely to distribute homogeneously into secretory granules. Therefore, a simple "self-aggregation default" theory may explain the little acknowledged, but commonly observed, tendency for both naturally occurring and exogenous content proteins to segregate from each other into distinct secretory granules.
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Affiliation(s)
- Jacqueline A. Sobota
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
| | - Francesco Ferraro
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
| | - Nils Bäck
- Department of Anatomy, Institute of Biomedicine, University of Helsinki, FIN-00014, Helsinki, Finland
| | - Betty A. Eipper
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
| | - Richard E. Mains
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
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Baum BJ, Tran SD. Synergy between genetic and tissue engineering: creating an artificial salivary gland. Periodontol 2000 2006; 41:218-23. [PMID: 16686936 DOI: 10.1111/j.1600-0757.2006.00160.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bruce J Baum
- Gene Transfer Section, NIDCR, National Institute of Health, Bethesda, Maryland, USA
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Abstract
Salivary glands have proven to be unusual but valuable target sites for multiple clinical gene transfer applications. Access to salivary glands for gene transfer is easy. Multiple studies in animal models have yielded proofs of concept for novel treatments for damaged salivary glands following therapeutic irraditation, in Sjögren's syndrome, and for gene therapeutics systemically by way of the blood-stream and locally in the oral cavity and upper gastrointestinal tract.
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Affiliation(s)
- Ana P Cotrim
- Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-1190, USA
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Garlov PE. Plasticity of nonapeptidergic neurosecretory cells in fish hypothalamus and neurohypophysis. ACTA ACUST UNITED AC 2006; 245:123-70. [PMID: 16125547 DOI: 10.1016/s0074-7696(05)45005-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The structure and function of nonapeptidergic neurosecretory cells (NP-NSC) are considered in terms of comparative morphology. Among NSC of different ergicity for NP-NSC the most characteristic involve massive accumulation and storage of neurohormonal products. Only in NP-NSC are the secretory cycles of functioning clearly expressed. Their highest reactivity is established during experimental and physiological stresses. In contrast, liberinergic, statinergic, and monoaminergic NSC, unlike NP-NSC, are characterized even in the "norm" by a constantly high level of extrusion processes. As signs of maximum NP-NSC plasticity, we consider the largest size of elementary neurosecretory granules, the diversity of secretion forms, and the maximum development of Herring bodies-clear manifestations of secretory cycles of functioning. In particular, phases of massive storage of neurosecretory granules in the extrusion cycle of NP-NSC neurosecretory terminals express accumulation of neurosecretory products. It is concluded that a particularly high degree of plasticity of NP-NSC is provided by their capability for functional reversion. This reversion is manifested first in the form of the restoration of the initial moderate level of functioning and especially in the accumulation of neurosecretory products. The reversion is considered an important mechanism providing a high degree of NSC plasticity. This degree turns out to be sufficient for participation of NP-NSC in the integration of fish reproduction. It is shown that NP-NSC are organized by the principle of a triad of the balanced system. This system consists of two alternative states: accumulation and release of neurosecretory products and the center of control of dynamics of their interrelations, the self-regulating center. In the latter, the key role is probably played by the Golgi complex.
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Garcia AL, Han SK, Janssen WG, Khaing ZZ, Ito T, Glucksman MJ, Benson DL, Salton SRJ. A prohormone convertase cleavage site within a predicted alpha-helix mediates sorting of the neuronal and endocrine polypeptide VGF into the regulated secretory pathway. J Biol Chem 2005; 280:41595-608. [PMID: 16221685 DOI: 10.1074/jbc.m509122200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Distinct intracellular pathways are involved in regulated and constitutive protein secretion from neuronal and endocrine cells, yet the peptide signals and molecular mechanisms responsible for targeting and retention of soluble proteins in secretory granules are incompletely understood. By using confocal microscopy and subcellular fractionation, we examined trafficking of the neuronal and endocrine peptide precursor VGF that is stored in large dense core vesicles and undergoes regulated secretion. VGF cofractionated with secretory vesicle membranes but was not detected in detergent-resistant lipid rafts. Deletional analysis using epitope-tagged VGF suggested that the C-terminal 73-amino acid fragment of VGF, containing two predicted alpha-helical loops and four potential prohormone convertase (PC) cleavage sites, was necessary and sufficient with an N-terminal signal peptide-containing domain, for large dense core vesicle sorting and regulated secretion from PC12 and INS-1 cells. Further transfection analysis identified the sorting sequence as a compact C-terminal alpha-helix and embedded 564RRR566 PC cleavage site; mutation of the 564RRR566 PC site in VGF-(1-65): GFP:VGF-(545-617) blocked regulated secretion, whereas disruption of the alpha-helix had no effect. Mutation of the adjacent 567HFHH570 motif, a charged region that might enhance PC cleavage in acidic environments, also blocked regulated release. Finally, inhibition of PC cleavage in PC12 cells using the membrane-permeable synthetic peptide chloromethyl ketone (decanoyl-RVKR-CMK) blocked regulated secretion of VGF. Our studies define a critical RRR-containing C-terminal domain that targets VGF into the regulated pathway in neuronal PC12 and endocrine INS-1 cells, providing additional support for the proposed role that PCs and their cleavage sites play in regulated peptide secretion.
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Affiliation(s)
- Angelo L Garcia
- Fishberg Department of Neuroscience, Mount Sinai School of Medicine, New York, New York 10029, USA
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Guan JS, Xu ZZ, Gao H, He SQ, Ma GQ, Sun T, Wang LH, Zhang ZN, Lena I, Kitchen I, Elde R, Zimmer A, He C, Pei G, Bao L, Zhang X. Interaction with vesicle luminal protachykinin regulates surface expression of delta-opioid receptors and opioid analgesia. Cell 2005; 122:619-31. [PMID: 16122428 DOI: 10.1016/j.cell.2005.06.010] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 04/11/2005] [Accepted: 06/07/2005] [Indexed: 11/24/2022]
Abstract
Opioid and tachykinin systems are involved in modulation of pain transmission in the spinal cord. Regulation of surface opioid receptors on nociceptive afferents is critical for opioid analgesia. Plasma-membrane insertion of delta-opioid receptors (DORs) is induced by stimulus-triggered exocytosis of DOR-containing large dense-core vesicles (LDCVs), but how DORs become sorted into the regulated secretory pathway is unknown. Here we report that direct interaction between protachykinin and DOR is responsible for sorting of DORs into LDCVs, allowing stimulus-induced surface insertion of DORs and DOR-mediated spinal analgesia. This interaction is mediated by the substance P domain of protachykinin and the third luminal domain of DOR. Furthermore, deletion of the preprotachykinin A gene reduced stimulus-induced surface insertion of DORs and abolished DOR-mediated spinal analgesia and morphine tolerance. Thus, protachykinin is essential for modulation of the sensitivity of nociceptive afferents to opioids, and the opioid and tachykinin systems are directly linked by protachykinin/DOR interaction.
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MESH Headings
- Afferent Pathways/drug effects
- Afferent Pathways/metabolism
- Afferent Pathways/ultrastructure
- Analgesics, Opioid/pharmacology
- Animals
- Cell Membrane/metabolism
- Cell Membrane/ultrastructure
- Cells, Cultured
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/ultrastructure
- Gene Deletion
- Male
- Mice
- Mice, Knockout
- Microscopy, Electron, Transmission
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Neurons, Afferent/ultrastructure
- Nociceptors/drug effects
- Nociceptors/metabolism
- Nociceptors/ultrastructure
- PC12 Cells
- Pain/drug therapy
- Pain/metabolism
- Pain/physiopathology
- Protein Precursors/chemistry
- Protein Precursors/genetics
- Protein Precursors/metabolism
- Protein Structure, Tertiary/physiology
- Rats
- Receptor Aggregation/physiology
- Receptors, Cell Surface/metabolism
- Receptors, Opioid, delta/metabolism
- Secretory Vesicles/metabolism
- Secretory Vesicles/ultrastructure
- Substance P/chemistry
- Substance P/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Tachykinins/chemistry
- Tachykinins/genetics
- Tachykinins/metabolism
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Affiliation(s)
- Ji-Song Guan
- Institute of Neuroscience, Key Laboratory of Neurobiology, Chinese Academy of Sciences, Shanghai 200031, China
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19
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Wang J, Cawley NX, Voutetakis A, Rodriguez YM, Goldsmith CM, Nieman LK, Hoque ATMS, Frank SJ, Snell CR, Loh YP, Baum BJ. Partial redirection of transgenic human growth hormone secretion from rat salivary glands. Hum Gene Ther 2005; 16:571-83. [PMID: 15916482 DOI: 10.1089/hum.2005.16.571] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Regulated secretory pathway proteins, when delivered as transgenes to salivary glands, are secreted predominantly into saliva. This is not useful for those proteins whose therapeutic function is required systemically, for example, human growth hormone (hGH). One strategy to improve the efficiency of hGH secretion into the bloodstream involves manipulation of existing sorting signals. The C terminus of hGH is highly conserved and contains a domain similar to the regulated pathway sorting domain of pro-opiomelanocortin (POMC). We hypothesized that, similar to POMC, mutation of this domain would divert hGH secretion from the regulated to the constitutive pathway, which in salivary glands leads to the bloodstream. Several mutations were made in the C terminus of the hGH cDNA and tested in vitro. One biologically active mutant containing E174A and E186A substitutions, and with an included C-terminal extension, was studied in greater detail. Compared with wild-type hGH, we found that this mutant hGH accumulated in the Golgi/trans-Golgi network and showed increased basal secretion in AtT20 cells, a model endocrine cell line. Importantly, in vivo, the mutant hGH displayed a relative increase in the proportion of constitutive pathway secretion seen from rat salivary glands, with a significantly lower saliva-versus-serum secretion ratio (p=0.03). Although this mutant is unlikely to be therapeutically beneficial, these results suggest that the final destination of a transgenic secretory protein may be controlled by reengineering its sorting determinants.
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Affiliation(s)
- Jianghua Wang
- Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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20
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Gorr SU, Venkatesh S, Darling D. Parotid secretory granules: crossroads of secretory pathways and protein storage. J Dent Res 2005; 84:500-9. [PMID: 15914585 PMCID: PMC1939692 DOI: 10.1177/154405910508400604] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Saliva plays an important role in digestion, host defense, and lubrication. The parotid gland contributes a variety of secretory proteins-including amylase, proline-rich proteins, and parotid secretory protein (PSP)-to these functions. The regulated secretion of salivary proteins ensures the availability of the correct mix of salivary proteins when needed. In addition, the major salivary glands are targets for gene therapy protocols aimed at targeting therapeutic proteins either to the oral cavity or to circulation. To be successful, such protocols must be based on a solid understanding of protein trafficking in salivary gland cells. In this paper, model systems available to study the secretion of salivary proteins are reviewed. Parotid secretory proteins are stored in large dense-core secretory granules that undergo stimulated secretion in response to extracellular stimulation. Secretory proteins that are not stored in large secretory granules are secreted by either the minor regulated secretory pathway, constitutive secretory pathways (apical or basolateral), or the constitutive-like secretory pathway. It is proposed that the maturing secretory granules act as a distribution center for secretory proteins in salivary acinar cells. Protein distribution or sorting is thought to involve their selective retention during secretory granule maturation. Unlike regulated secretory proteins in other cell types, salivary proteins do not exhibit calcium-induced aggregation. Instead, sulfated proteoglycans play a role in the storage of secretory proteins in parotid acinar cells. This work suggests that unique sorting and retention mechanisms are responsible for the distribution of secretory proteins to different secretory pathways from the maturing secretory granules in parotid acinar cells.
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Affiliation(s)
- S.-U. Gorr
- Department of Periodontics, Endodontics and Dental Hygiene and Center for Oral Health and Systemic Disease, University of Louisville School of Dentistry, Louisville, KY 40292, USA
| | - S.G. Venkatesh
- Department of Periodontics, Endodontics and Dental Hygiene and Center for Oral Health and Systemic Disease, University of Louisville School of Dentistry, Louisville, KY 40292, USA
| | - D.S. Darling
- Department of Periodontics, Endodontics and Dental Hygiene and Center for Oral Health and Systemic Disease, University of Louisville School of Dentistry, Louisville, KY 40292, USA
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21
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Abstract
Directing the local or systemic expression of therapeutic proteins is a potentially important clinical application of gene transfer technology. Gene-based therapeutics theoretically offer many advantages over protein therapeutics. Numerous tissues have been evaluated for this purpose in animal models, most commonly the liver and skeletal muscle. Based on pre-clinical studies, we suggest that salivary glands are a valuable, yet under-appreciated, target tissue for both systemic and upper gastrointestinal tract gene therapeutic applications.
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Affiliation(s)
- Bruce J Baum
- Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, DHHS, Bethesda, MD 20892-1190, USA
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22
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Cardinaud B, Darré-Toulemonde F, Duhault J, Boutin JA, Nahon JL. Comparative analysis of melanin-concentrating hormone structure and activity in fishes and mammals. Peptides 2004; 25:1623-32. [PMID: 15476929 DOI: 10.1016/j.peptides.2004.05.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2004] [Accepted: 05/26/2004] [Indexed: 10/26/2022]
Abstract
A comparative analysis of the structure of the melanin-concentrating hormone (MCH) precursor reveals that this sequence has been subjected to a higher selection pressure in mammals than in teleosts, suggesting that the structural constraints have not been the same throughout the vertebrate lineage. In contrast, the MCH peptide sequence has been very well conserved in all species. A sensitive and reproducible eel skin assay was developed and allowed us to define the structural features needed for a full MCH bioactivity. It was shown that the minimal structure carrying the critical residues was the same in fishes and in mammals. A pharmacological approach confirmed that MCH receptor activation decreased the cAMP levels in the fish skin, but this effect appeared to be independent from a Galphai protein. We propose that one of the intracellular signaling pathways of the MCH receptor in fish skin is the activation of one or several cellular phosphodiesterases.
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Affiliation(s)
- Bruno Cardinaud
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 6097, 660 route des Lucioles, Sophia Antipolis, Valbonne 06560, France
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23
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Meldolesi J, Chieregatti E, Luisa Malosio M. Requirements for the identification of dense-core granules. Trends Cell Biol 2004; 14:13-9. [PMID: 14729176 DOI: 10.1016/j.tcb.2003.11.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dense-core granules (DCGs), cytoplasmic organelles competent for regulated exocytosis, show considerable heterogeneity depending upon the specificity of their expressing cells--primarily neurons and neurosecretory cells. DCGs have been mainly identified by detecting their cargo molecules, often members of the granin family, and using conventional electron microscopy and immunocytochemistry. However, by a critical analysis of the various stages of DCG "life" within neurosecretory cells, we have highlighted several specific molecular and functional properties that are common to all these organelles. We propose that these properties be considered as strict requirements for the identification of DCGs.
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Affiliation(s)
- Jacopo Meldolesi
- Vita-Salute San Raffaele University and Scientific Institute San Raffaele, Department of Neuroscience and Immunology, Centre of Excellence in Physiopathology of Cell Differentiation, via Olgettina 58, 20132 Milan, Italy.
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24
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Ohsawa Y, Zhang G, Kametaka S, Shibata M, Koike M, Waguri S, Uchiyama Y. Purification, cDNA cloning, and secretory properties of FLRG protein from PC12 cells and the distribution of FLRG mRNA and protein in rat tissues. ACTA ACUST UNITED AC 2004; 66:367-81. [PMID: 14692692 DOI: 10.1679/aohc.66.367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A 35 kD protein was isolated and purified from conditioned media of Bcl-2 cDNA-transfected PC12 cells and its cDNA cloned. A database analysis showed that the 35 kD protein is a rat homologue of the human FLRG protein. The biochemical as well as morphological properties of the rat FLRG protein in PC12 cells were examined and its distribution in rat tissues determined. The levels of FLRG mRNA expressed were low during the fetal period, compared with those of follistatin mRNA. The distribution of FLRG and follistatin mRNAs differed from each other after birth; the expression levels of FLRG mRNA were abundant in the adrenal gland and testis, whereas those of follistatin mRNA and activin A were markedly high in the ovary. The presence of FLRG mRNA and/or protein was confirmed in spermatocytes at various differentiating stages andin endocrine cells of both the adrenal cortex and medulla. When overexpressed in PC12 cells, the FLRG protein was found to be stored in secretory granules of the cells and largely secreted by a regulated pathway, while activin A enhancedthe constitutive secretion of the FLRG protein from wild-typpe PC12 cells, indicating that the FLRG protein possesses dualproperties in secretory pathways. The different distribution between FLRG and follistatin mRNA suggests that, like follistatin in the ovary, the FLRG protein may be involved in the maintenance of spermatogenesis in the testis and the growth and function of adrenal tissue cells, probably by regulating the functions of its binding partners such as the TGF-beta ( superfamily members.
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Affiliation(s)
- Yoshiyuki Ohsawa
- Department of Cell Biology and Neurosciences, Osaka University Graduated School of Medicine, Suita, Osaka, Japan
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25
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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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26
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Voutetakis A, Wang J, Baum BJ. Utilizing endocrine secretory pathways in salivary glands for systemic gene therapeutics. J Cell Physiol 2004; 199:1-7. [PMID: 14978729 DOI: 10.1002/jcp.10429] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mammalian salivary glands are commonly used models of exocrine secretion. However, there is substantial experimental evidence showing the physiological existence of endocrine secretory pathways in these tissues. The use of gene transfer technology in vivo has allowed the unambiguous demonstration of these endocrine pathways. We and others have exploited such findings and evaluated salivary glands as possible target tissues for systemic applications of gene therapeutics. Salivary glands present numerous advantages for this purpose, including being well encapsulated, which limits extra-glandular vector dissemination, and having the luminal membranes of almost all parenchymal cells accessible via intraoral delivery of vectors through the main excretory ducts. Existing studies suggest that clinical benefits will result from salivary gland targeted systemic gene therapeutics.
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Affiliation(s)
- Antonis Voutetakis
- Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, DHHS, Bethesda, Maryland 20892-1190, USA
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27
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Rosen H, Gao Y, Johnsson E, Olsson I. Artificially controlled aggregation of proteins and targeting in hematopoietic cells. J Leukoc Biol 2003; 74:800-9. [PMID: 12960262 DOI: 10.1189/jlb.0203066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The targeting mechanisms for granule proteins in hematopoietic cells are largely unknown. Aggregation is believed to be important for protein sorting-for-entry and sorting-by-retention in endocrine and neuroendocrine cells. We asked whether artificially induced multimerization/aggregation of chimeric proteins could affect their sorting in hematopoietic cells. A system was used that permits ligand-controlled intracellular oligomerization of hybrid proteins containing the FK506-binding protein (FKBP). The hybrid proteins ELA-(FKBP)3 with neutrophil elastase (ELA) and (FKBP*)4-FCS-hGH with a furin cleavage site (FCS) and human growth hormone (hGH) were expressed in the myeloblastic 32D and the rat basophilic leukemia (RBL-1) hematopoietic cell lines. ELA alone is normally targeted to secretory lysosomes. However, the hybrid proteins and ligand-induced aggregates of them were constitutively secreted and not targeted. The hGH that was released at the FCS in (FKBP*)4-FCS-hGH was also constitutively secreted. We conclude that protein multimerization/aggregation per se is not enough to facilitate sorting-for-entry to secretory lysosomes in hematopoietic cells and that improperly folded proteins may be eliminated from sorting by constitutive secretion.
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28
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Venkatesh SG, Cowley DJ, Gorr SU. Differential aggregation properties of secretory proteins that are stored in exocrine secretory granules of the pancreas and parotid glands. Am J Physiol Cell Physiol 2003; 286:C365-71. [PMID: 14576088 DOI: 10.1152/ajpcell.00338.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Low-pH- and calcium-induced aggregation of regulated secretory proteins has been proposed to play a role in their retention and storage in secretory granules. However, this has not been tested for secretory proteins that are stored in the exocrine parotid secretory granules. Parotid granule matrix proteins were analyzed for aggregation in the presence or absence of calcium and in the pH range of 5.5 to 7.5. Amylase did not aggregate under these conditions, although <10% of parotid secretory protein (PSP) aggregated below pH 6.0. To test aggregation directly in isolated granules, rat parotid secretory granules were permeabilized with 0.1% saponin in the presence or absence of calcium and in the pH range of 5.0 to 8.4. In contrast to the low-pH-dependent retention of amylase in exocrine pancreatic granules, amylase was quantitatively released and most PSP was released from parotid granules under all conditions. Both proteins were completely released upon granule membrane solubilization. Thus neither amylase nor PSP show low-pH- or calcium-induced aggregation under physiological conditions in the exocrine parotid secretory granules.
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Affiliation(s)
- S G Venkatesh
- Department of Periodontics, Endodontics, and Dental Hygiene, University of Louisville Health Sciences Center, Louisville, KY 40292, USA
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29
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Landry M, Vila-Porcile E, Hökfelt T, Calas A. Differential routing of coexisting neuropeptides in vasopressin neurons. Eur J Neurosci 2003. [DOI: 10.1046/j.1460-9568.2002.00162.x-i1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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30
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Landry M, Vila-Porcile E, Hökfelt T, Calas A. Differential routing of coexisting neuropeptides in vasopressin neurons. Eur J Neurosci 2003; 17:579-89. [PMID: 12814355 DOI: 10.1046/j.1460-9568.2003.02472.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The functional implications of intraneuronal coexistence of different neuropeptides depend on their respective targeting to release sites. In the rat hypothalamic magnocellular neurons, we investigated a possible differential routing of the coexpressed galanin and vasopressin. The respective location of proteins and messengers was assessed with double immunogold and in situ hybridization combining confocal and electron microscope analysis. The various populations of labelled granules were quantitatively compared in three subcellular compartments: perikarya, local processes and posthypophyseal nerve endings. Three subpopulations of granules were detected in all three compartments, but their respective amount showed significant differences. Galanin alone was immunolocalized in some secretory granules, vasopressin alone in others, and both peptides in a third subpopulation of granules. The major part of the granules containing vasopressin, either alone or in association with galanin, is found in neurohypophyseal nerve endings. In contrast, galanin single-labelled granules represent the most abundant population in dendritic processes, while double-labelled granules are more numerous in perikarya. This indicates a preferential distribution of the two peptides in the different compartments of magnocellular neurons. Furthermore, galanin and vasopressin messenger RNAs were detected at different domains of the endoplasmic reticulum, suggesting that translation might also occur at different locations, thus leading to partial segregation of galanin and vasopressin cargoes between two populations of secretory granules. The present study provides, for the first time in mammals, evidence suggesting that galanin and vasopressin are only partly copackaged and undergo a preferential targeting toward dendrites or neurohypophysis, suggesting different functions, autocrine/paracrine and endocrine, respectively.
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Affiliation(s)
- Marc Landry
- INSERM EPI 9914, Institut François Magendie, Université Victor Segalen, Bordeaux, France.
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31
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Romani de Wit T, de Leeuw HPJC, Rondaij MG, de Laaf RTM, Sellink E, Brinkman HJ, Voorberg J, van Mourik JA. Von Willebrand factor targets IL-8 to Weibel-Palade bodies in an endothelial cell line. Exp Cell Res 2003; 286:67-74. [PMID: 12729795 DOI: 10.1016/s0014-4827(03)00094-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Vascular endothelial cells are able to store the chemotactic cytokine interleukin-8 (IL-8) in specialized storage vesicles, Weibel-Palade bodies, together with von Willebrand factor (VWF) and P-selectin. We investigated whether VWF plays a role in the sorting of IL-8 into these organelles. We examined the effect of VWF expression on IL-8 targeting in an endothelial cell line (EC-RF24). This cell line has retained the typical phenotypic characteristics of primary endothelial cells but has lost the capacity to produce VWF in appreciable amounts. EC-RF24 cells were retrovirally transduced with a vector encoding a VWF-green fluorescent protein chimera (VWF-GFP). This approach enables direct visualization of the cellular distribution and secretory behavior of the VWF-GFP hybrid. Expression of VWF-GFP resulted in the generation of Weibel-Palade body-like organelles as shown by the colocalization of VWF-GFP and P-selectin. VWF-GFP expressing EC-RF24 cells also showed significant colocalization of VWF-GFP with IL-8 in these storage vesicles. Live cell imaging revealed that the number of VWF-GFP-containing granules decreased upon cell stimulation. These observations indicate that VWF plays an active role in sequestering IL-8 into Weibel-Palade bodies.
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Affiliation(s)
- Thalia Romani de Wit
- Department of Plasma Proteins and Blood Coagulation, CLB, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands
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32
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Feldman SA, Eiden LE. The chromogranins: their roles in secretion from neuroendocrine cells and as markers for neuroendocrine neoplasia. Endocr Pathol 2003; 14:3-23. [PMID: 12746559 DOI: 10.1385/ep:14:1:3] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chromogranins are the major components of the secretory granules of most neuroendocrine cells. Within the secretory pathway, chromogranins are involved in granulogenesis, and in sorting and processing of secretory protein cargo prior to secretion. Once secreted, they have hormonal, autocrine, and paracrine activities. The chromogranin family includes chromogranins A (CgA) and B (CgB) and secretogranin II (SgII, once called chromogranin C). The related "granins" NESP55, 7B2, secretogranin III/1B 1075 (SgIII), and secretogranin IV/HISL-19 antigen (SgIV), are also sometimes included when considering the chromogranins. While it is useful to consider the granin proteins as a family with many common features, it is also necessary to examine the distinct features and properties of individual members of the granin family to understand fully their functions, employ them efficiently as tissue, serum, and urinary markers for neuroendocrine neoplasia, and develop an evolutionary-biologic perspective on their contribution to mammalian physiology. Recent advances in chromogranin research include establishing the role of CgA in granulogenesis and the role of CgB in nuclear transcription; new biologic activities for CgA-, CgB-, and SgII-derived peptides; and new marker functions for granins and their proteolytically processed products in endocrine neoplasias.
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Affiliation(s)
- Steven A Feldman
- Section on Molecular Virology, Laboratory of Cellular and Molecular Regulation, National Institutes of Health, Bethesda MD 20892-4090, USA
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33
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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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34
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Cowley DJ, Chu M, Gorr SU. Sorting of an exocrine secretory protein to the regulated secretory pathway in endocrine cells. Biochem Biophys Res Commun 2002; 299:98-101. [PMID: 12435394 DOI: 10.1016/s0006-291x(02)02576-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Regulated secretory proteins are stored in secretory granules. While the sorting and storage process appears similar in endocrine and exocrine cells, the extent of overlap of sorting between endocrine and exocrine cell types is not clear. It is predicted that exocrine regulated secretory proteins that are stored with high efficiency in exocrine granules would also be stored efficiently in endocrine granules. To test this hypothesis, parotid secretory protein (PSP), which is stored efficiently in parotid acinar cells, was expressed in the endocrine cell lines GH4C1 and PC12. PSP undergoes stimulated secretion in both cell types. Secretion is similar to that of the endocrine regulated secretory protein chromogranin A but distinct from secreted alkaline phosphatase, a marker for the constitutive secretory pathway in endocrine cells. Subcellular fractionation of GH4C1 cells revealed that PSP co-fractionates with chromogranin A but not with secreted alkaline phosphatase.
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Affiliation(s)
- Darrin J Cowley
- Department of Periodontics, Endodontics and Dental Hygiene, University of Louisville Health Sciences Center, Louisville, KY 40292, USA
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35
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Lavoie C, Meerloo T, Lin P, Farquhar MG. Calnuc, an EF-hand Ca(2+)-binding protein, is stored and processed in the Golgi and secreted by the constitutive-like pathway in AtT20 cells. Mol Endocrinol 2002; 16:2462-74. [PMID: 12403836 DOI: 10.1210/me.2002-0079] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Calnuc is an ubiquitous, EF-hand Ca(2+) binding protein found in the cytoplasm where it binds to Galphai3, in the Golgi lumen where it constitutes a Ca(2+) storage pool, and secreted outside the cell. Here we investigated the pathway of secretion of calnuc in AtT20 cells. We found by pulse-chase experiments that calnuc is synthesized in the endoplasmic reticulum, transported to the Golgi where it remains greater than 12 h and undergoes posttranslational modification (O-glycosylation and sulfation) followed by secretion into the culture medium. We examined if calnuc is secreted by the constitutive or regulated secretory pathway in AtT20 cells. By immunofluorescence and immunogold labeling, endogenous calnuc is found in immature secretion granules (ISG) but not mature regulated secretory granules (RSG), whereas overexpressed calnuc-green fluorescent protein (GFP) is found in both ISG and RSG, where it colocalizes with ACTH. Neither calnuc nor calnuc-GFP are released by the regulated secretory pathway, suggesting that endogenous calnuc and calnuc-GFP are progressively removed from ISG and RSG during granule maturation. We conclude that calnuc is secreted via the constitutive-like pathway and represents a useful endogenous marker for this pathway in AtT20 cells. Together, these observations indicate that calnuc has a unique itinerary as it is retained in the Golgi and is then constitutively secreted extracellularly where it may influence cell behavior via its Ca(2+)-binding properties.
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Affiliation(s)
- Christine Lavoie
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92093-0651, USA
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36
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Venkatesh SG, Gorr SU. A sulfated proteoglycan is necessary for storage of exocrine secretory proteins in the rat parotid gland. Am J Physiol Cell Physiol 2002; 283:C438-45. [PMID: 12107053 DOI: 10.1152/ajpcell.00552.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sulfated proteoglycans have been proposed to play a role in the sorting and storage of secretory proteins in exocrine secretory granules. Rat parotid acinar cells expressed a 40- to 60-kDa proteoglycan that was stored in secretory granules. Treatment of the tissue with the proteoglycan synthesis inhibitor paranitrophenyl xyloside resulted in the complete abrogation of the sulfated proteoglycan. Pulse-chase experiments in the presence of the xyloside analog showed a significant reduction in the stimulated secretion and granule storage of the newly synthesized regulated secretory proteins amylase and parotid secretory protein. Inhibition of proteoglycan sulfation by chlorate did not affect the sorting of these proteins. The effect of proteoglycan synthesis inhibition on protein sorting was completely reversed upon treatment with a weak acid. These results suggest that the sulfated proteoglycan is necessary for sorting and storage of regulated secretory proteins in the exocrine parotid gland. Preliminary evidence suggests that the mechanism involves the modulation of granule pH by the proteoglycan rather than a direct interaction with other granule components.
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Affiliation(s)
- S G Venkatesh
- Department of Periodontics, Endodontics, and Dental Hygiene, University of Louisville Health Sciences Center, Louisville, Kentucky 40292, USA
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37
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Tasiemski A, Hammad H, Vandenbulcke F, Breton C, Bilfinger TJ, Pestel J, Salzet M. Presence of chromogranin-derived antimicrobial peptides in plasma during coronary artery bypass surgery and evidence of an immune origin of these peptides. Blood 2002; 100:553-9. [PMID: 12091348 DOI: 10.1182/blood.v100.2.553] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chromogranin A (CGA) and chromogranin B (CGB) are acidic proteins stored in secretory organelles of endocrine cells and neurons. In addition to their roles as helper proteins in the packaging of peptides, they may serve as prohormones to generate biologically active peptides such as vasostatin-1 and secretolytin. These molecules derived from CGA and CGB, respectively, possess antimicrobial properties. The present study demonstrates that plasmatic levels of both vasostatin-1 and secretolytin increase during surgery in patients undergoing cardiopulmonary bypass (CPB). Vasostatin-1 and secretolytin, initially present in plasma at low levels, are released just after skin incision. Consequently, they can be added to enkelytin, an antibacterial peptide derived from proenkephalin A, for the panoply of components acting as a first protective barrier against hypothetical invasion of pathogens, which may occur during surgery. CGA and CGB, more commonly viewed as markers for endocrine and neuronal cells, were also found to have an immune origin. RNA messengers coding for CGB were amplified by reverse transcription-polymerase chain reaction in human monocytes, and immunocytochemical analysis by confocal microscopy revealed the presence of CGA or CGB or both in monocytes and neutrophils. A combination of techniques including confocal microscopic analysis, mass spectrometry measurement, and antibacterial tests allowed for the identification of the positive role of interleukin 6 (IL-6) in the secretolytin release from monocytes in vitro. Because IL-6 release is known to be strongly enhanced during CPB, we suggest a possible relationship between IL-6 and the increased level of secretolytin in patients undergoing CPB.
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Affiliation(s)
- Aurélie Tasiemski
- Laboratoire de Neuroimmunologie des Annélides, Université des Sciences et Technologies de Lille, Villeneuve d'ascq, France
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38
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Abstract
Cellular membranes act as semipermeable barriers to ions and macromolecules. Specialized mechanisms of transport of proteins across membranes have been developed during evolution. There are common mechanistic themes among protein translocation systems in bacteria and in eukaryotic cells. Here we review current understanding of mechanisms of protein transport across the bacterial plasma membrane as well as across several organelle membranes of yeast and mammalian cells. We consider a variety of organelles including the endoplasmic reticulum, outer and inner membranes of mitochondria, outer, inner, and thylakoid membranes of chloroplasts, peroxisomes, and lysosomes. Several common principles are evident: (a) multiple pathways of protein translocation across membranes exist, (b) molecular chaperones are required in the cytosol, inside the organelle, and often within the organelle membrane, (c) ATP and/or GTP hydrolysis is required, (d) a proton-motive force across the membrane is often required, and (e) protein translocation occurs through gated, aqueous channels. There are exceptions to each of these common principles indicating that our knowledge of how proteins translocate across membranes is not yet complete.
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Affiliation(s)
- F A Agarraberes
- Department of Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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