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Kisaretova P, Tsybko A, Bondar N, Reshetnikov V. Molecular Abnormalities in BTBR Mice and Their Relevance to Schizophrenia and Autism Spectrum Disorders: An Overview of Transcriptomic and Proteomic Studies. Biomedicines 2023; 11:biomedicines11020289. [PMID: 36830826 PMCID: PMC9953015 DOI: 10.3390/biomedicines11020289] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/22/2023] Open
Abstract
Animal models of psychopathologies are of exceptional interest for neurobiologists because these models allow us to clarify molecular mechanisms underlying the pathologies. One such model is the inbred BTBR strain of mice, which is characterized by behavioral, neuroanatomical, and physiological hallmarks of schizophrenia (SCZ) and autism spectrum disorders (ASDs). Despite the active use of BTBR mice as a model object, the understanding of the molecular features of this strain that cause the observed behavioral phenotype remains insufficient. Here, we analyzed recently published data from independent transcriptomic and proteomic studies on hippocampal and corticostriatal samples from BTBR mice to search for the most consistent aberrations in gene or protein expression. Next, we compared reproducible molecular signatures of BTBR mice with data on postmortem samples from ASD and SCZ patients. Taken together, these data helped us to elucidate brain-region-specific molecular abnormalities in BTBR mice as well as their relevance to the anomalies seen in ASDs or SCZ in humans.
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Affiliation(s)
- Polina Kisaretova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Prospekt Akad. Lavrentyeva 10, Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
| | - Anton Tsybko
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Prospekt Akad. Lavrentyeva 10, Novosibirsk 630090, Russia
| | - Natalia Bondar
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Prospekt Akad. Lavrentyeva 10, Novosibirsk 630090, Russia
| | - Vasiliy Reshetnikov
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Prospekt Akad. Lavrentyeva 10, Novosibirsk 630090, Russia
- Department of Biotechnology, Sirius University of Science and Technology, 1 Olympic Avenue, Sochi 354340, Russia
- Correspondence:
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Chaplot K, Jarvela TS, Lindberg I. Secreted Chaperones in Neurodegeneration. Front Aging Neurosci 2020; 12:268. [PMID: 33192447 PMCID: PMC7481362 DOI: 10.3389/fnagi.2020.00268] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/03/2020] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis, or proteostasis, is a combination of cellular processes that govern protein quality control, namely, protein translation, folding, processing, and degradation. Disruptions in these processes can lead to protein misfolding and aggregation. Proteostatic disruption can lead to cellular changes such as endoplasmic reticulum or oxidative stress; organelle dysfunction; and, if continued, to cell death. A majority of neurodegenerative diseases involve the pathologic aggregation of proteins that subverts normal neuronal function. While prior reviews of neuronal proteostasis in neurodegenerative processes have focused on cytoplasmic chaperones, there is increasing evidence that chaperones secreted both by neurons and other brain cells in the extracellular – including transsynaptic – space play important roles in neuronal proteostasis. In this review, we will introduce various secreted chaperones involved in neurodegeneration. We begin with clusterin and discuss its identification in various protein aggregates, and the use of increased cerebrospinal fluid (CSF) clusterin as a potential biomarker and as a potential therapeutic. Our next secreted chaperone is progranulin; polymorphisms in this gene represent a known genetic risk factor for frontotemporal lobar degeneration, and progranulin overexpression has been found to be effective in reducing Alzheimer’s- and Parkinson’s-like neurodegenerative phenotypes in mouse models. We move on to BRICHOS domain-containing proteins, a family of proteins containing highly potent anti-amyloidogenic activity; we summarize studies describing the biochemical mechanisms by which recombinant BRICHOS protein might serve as a therapeutic agent. The next section of the review is devoted to the secreted chaperones 7B2 and proSAAS, small neuronal proteins which are packaged together with neuropeptides and released during synaptic activity. Since proteins can be secreted by both classical secretory and non-classical mechanisms, we also review the small heat shock proteins (sHsps) that can be secreted from the cytoplasm to the extracellular environment and provide evidence for their involvement in extracellular proteostasis and neuroprotection. Our goal in this review focusing on extracellular chaperones in neurodegenerative disease is to summarize the most recent literature relating to neurodegeneration for each secreted chaperone; to identify any common mechanisms; and to point out areas of similarity as well as differences between the secreted chaperones identified to date.
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Affiliation(s)
- Kriti Chaplot
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Timothy S Jarvela
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, University of Maryland, Baltimore, Baltimore, MD, United States
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Petrella C, Di Certo MG, Barbato C, Gabanella F, Ralli M, Greco A, Possenti R, Severini C. Neuropeptides in Alzheimer’s Disease: An Update. Curr Alzheimer Res 2019; 16:544-558. [DOI: 10.2174/1567205016666190503152555] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/19/2019] [Accepted: 04/30/2019] [Indexed: 12/19/2022]
Abstract
Neuropeptides are small proteins broadly expressed throughout the central nervous system, which act as neurotransmitters, neuromodulators and neuroregulators. Growing evidence has demonstrated the involvement of many neuropeptides in both neurophysiological functions and neuropathological conditions, among which is Alzheimer’s disease (AD). The role exerted by neuropeptides in AD is endorsed by the evidence that they are mainly neuroprotective and widely distributed in brain areas responsible for learning and memory processes. Confirming this point, it has been demonstrated that numerous neuropeptide-containing neurons are pathologically altered in brain areas of both AD patients and AD animal models. Furthermore, the levels of various neuropeptides have been found altered in both Cerebrospinal Fluid (CSF) and blood of AD patients, getting insights into their potential role in the pathophysiology of AD and offering the possibility to identify novel additional biomarkers for this pathology. We summarized the available information about brain distribution, neuroprotective and cognitive functions of some neuropeptides involved in AD. The main focus of the current review was directed towards the description of clinical data reporting alterations in neuropeptides content in both AD patients and AD pre-clinical animal models. In particular, we explored the involvement in the AD of Thyrotropin-Releasing Hormone (TRH), Cocaine- and Amphetamine-Regulated Transcript (CART), Cholecystokinin (CCK), bradykinin and chromogranin/secretogranin family, discussing their potential role as a biomarker or therapeutic target, leaving the dissertation of other neuropeptides to previous reviews.
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Affiliation(s)
- Carla Petrella
- Department of Sense Organs, CNR, Institute of Cell Biology and Neurobiology, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Maria Grazia Di Certo
- Department of Sense Organs, CNR, Institute of Cell Biology and Neurobiology, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Christian Barbato
- Department of Sense Organs, CNR, Institute of Cell Biology and Neurobiology, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Francesca Gabanella
- Department of Sense Organs, CNR, Institute of Cell Biology and Neurobiology, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Massimo Ralli
- Department of Sense Organs, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Antonio Greco
- Department of Sense Organs, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Roberta Possenti
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Cinzia Severini
- Department of Sense Organs, CNR, Institute of Cell Biology and Neurobiology, University Sapienza of Rome, Viale del Policlinico 155, 00161 Rome, Italy
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Jarvela TS, Womack T, Georgiou P, Gould TD, Eriksen JL, Lindberg I. 7B2 chaperone knockout in APP model mice results in reduced plaque burden. Sci Rep 2018; 8:9813. [PMID: 29955078 PMCID: PMC6023903 DOI: 10.1038/s41598-018-28031-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/08/2018] [Indexed: 01/18/2023] Open
Abstract
Impairment of neuronal proteostasis is a hallmark of Alzheimer's and other neurodegenerative diseases. However, the underlying molecular mechanisms leading to pathogenic protein aggregation, and the role of secretory chaperone proteins in this process, are poorly understood. We have previously shown that the neural-and endocrine-specific secretory chaperone 7B2 potently blocks in vitro fibrillation of Aβ42. To determine whether 7B2 can function as a chaperone in vivo, we measured plaque formation and performed behavioral assays in 7B2-deficient mice in an hAPPswe/PS1dE9 Alzheimer's model mouse background. Surprisingly, immunocytochemical analysis of cortical levels of thioflavin S- and Aβ-reactive plaques showed that APP mice with a partial or complete lack of 7B2 expression exhibited a significantly lower number and burden of thioflavin S-reactive, as well as Aβ-immunoreactive, plaques. However, 7B2 knockout did not affect total brain levels of either soluble or insoluble Aβ. While hAPP model mice performed poorly in the Morris water maze, their brain 7B2 levels did not impact performance. Since 7B2 loss reduced amyloid plaque burden, we conclude that brain 7B2 can impact Aβ disposition in a manner that facilitates plaque formation. These results are reminiscent of prior findings in hAPP model mice lacking the ubiquitous secretory chaperone clusterin.
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Affiliation(s)
- Timothy S Jarvela
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Tasha Womack
- Department of Pharmacology, College of Pharmacy, University of Houston, Houston, TX, USA
| | - Polymnia Georgiou
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Todd D Gould
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jason L Eriksen
- Department of Pharmacology, College of Pharmacy, University of Houston, Houston, TX, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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Dasgupta I, Sanglas L, Enghild JJ, Lindberg I. The neuroendocrine protein 7B2 is intrinsically disordered. Biochemistry 2012; 51:7456-64. [PMID: 22947085 PMCID: PMC3457758 DOI: 10.1021/bi300871k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The small neuroendocrine protein 7B2 has been shown to
be required
for the productive maturation of proprotein convertase 2 (proPC2)
to an active enzyme form; this action is accomplished via its ability
to block aggregation of proPC2 into nonactivatable forms. Recent data
show that 7B2 can also act as a postfolding chaperone to block the
aggregation of a number of other proteins, for example, α-synuclein.
To gain insight into the mechanism of action of 7B2 in blocking protein
aggregation, we performed structural studies of this protein using
gel filtration chromatography, intrinsic tryptophan fluorescence,
1-anilino-8-naphthalenesulfonate (ANS) binding, circular dichroism
(CD), and nuclear magnetic resonance (NMR) spectroscopy. Gel filtration
studies indicated that 7B2 exists as an extended monomer, eluting
at a molecular mass higher than that expected for a globular protein
of similar size. However, chemical cross-linking showed that 7B2 exhibits
concentration-dependent oligomerization. CD experiments showed that
both full-length 27 kDa 7B2 and the C-terminally truncated 21 kDa
form lack appreciable secondary structure, although the longer protein
exhibited more structural content than the latter, as demonstrated
by intrinsic and ANS fluorescence studies. NMR spectra confirmed the
lack of structure in native 7B2, but a disorder-to-order transition
was observed upon incubation with one of its client proteins, α-synuclein.
We conclude that 7B2 is a natively disordered protein whose function
as an antiaggregant chaperone is likely facilitated by its lack of
appreciable secondary structure and tendency to form oligomers.
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Affiliation(s)
- Indrani Dasgupta
- Department of Anatomy and Neurobiology, School of Medicine, University of Maryland-Baltimore, Baltimore, MD 21201, USA
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Yakovleva T, Marinova Z, Kuzmin A, Seidah NG, Haroutunian V, Terenius L, Bakalkin G. Dysregulation of dynorphins in Alzheimer disease. Neurobiol Aging 2007; 28:1700-8. [PMID: 16914231 DOI: 10.1016/j.neurobiolaging.2006.07.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 07/06/2006] [Accepted: 07/10/2006] [Indexed: 11/17/2022]
Abstract
The opioid peptides dynorphins may be involved in pathogenesis of Alzheimer disease (AD) by inducing neurodegeneration or cognitive impairment. To test this hypothesis, the dynorphin system was analyzed in postmortem samples from AD and control subjects, and subjects with Parkinson or cerebro-vascular diseases for comparison. Dynorphin A, dynorphin B and related neuropeptide nociceptin were determined in the Brodmann area 7 by radioimmunoassay. The precursor protein prodynorphin, processing convertase PC2 and the neuroendocrine pro7B2 and 7B2 proteins required for PC2 maturation were analyzed by Western blot. AD subjects displayed robustly elevated levels of dynorphin A and no differences in dynorphin B and nociceptin compared to controls. Subjects with Parkinson or cerebro-vascular diseases did not differ from controls with respect to any of the three peptides. PC2 levels were also increased, whereas, those of prodynorphin and pro7B2/7B2 were not changed in AD. Dynorphin A levels correlated with the neuritic plaque density. These results along with the known non-opioid ability of dynorphin A to induce neurodegeneration suggest a role for this neuropeptide in AD neuropathology.
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Affiliation(s)
- T Yakovleva
- Department of Clinical Neuroscience, CMM L8:01, Karolinska Institute and Hospital, SE-17176 Stockholm, Sweden
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Winsky-Sommerer R, Grouselle D, Rougeot C, Laurent V, David JP, Delacourte A, Dournaud P, Seidah NG, Lindberg I, Trottier S, Epelbaum J. The proprotein convertase PC2 is involved in the maturation of prosomatostatin to somatostatin-14 but not in the somatostatin deficit in Alzheimer's disease. Neuroscience 2004; 122:437-47. [PMID: 14614908 DOI: 10.1016/s0306-4522(03)00560-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A somatostatin deficit occurs in the cerebral cortex of Alzheimer's disease patients without a major loss in somatostatin-containing neurons. This deficit could be related to a reduction in the rate of proteolytic processing of peptide precursors. Since the two proprotein convertases (PC)1 and PC2 are responsible for the processing of neuropeptide precursors directed to the regulated secretory pathway, we examined whether they are involved first in the proteolytic processing of prosomatostatin in mouse and human brain and secondly in somatostatin defect associated with Alzheimer's disease. By size exclusion chromatography, the cleavage of prosomatostatin to somatostatin-14 is almost totally abolished in the cortex of PC2 null mice, while the proportions of prosomatostatin and somatostatin-28 are increased. By immunohistochemistry, PC1 and PC2 were localized in many neuronal elements in human frontal and temporal cortex. The convertases levels were quantified by Western blot, as well as the protein 7B2 which is required for the production of active PC2. No significant change in PC1 levels was observed in Alzheimer's disease. In contrast, a marked decrease in the ratio of the PC2 precursor to the total enzymatic pool was observed in the frontal cortex of Alzheimer patients. This decrease coincides with an increase in the binding protein 7B2. However, the content and enzymatic activity of the PC2 mature form were similar in Alzheimer patients and controls. Therefore, the cortical somatostatin defect is not due to convertase alteration occuring during Alzheimer's disease. Further studies will be needed to assess the mechanisms involved in somatostatin deficiency in Alzheimer's disease.
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Affiliation(s)
- R Winsky-Sommerer
- INSERM U549, IFR Broca-Sainte Anne, Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
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8
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Mbikay M, Seidah NG, Chrétien M. Neuroendocrine secretory protein 7B2: structure, expression and functions. Biochem J 2001; 357:329-42. [PMID: 11439082 PMCID: PMC1221959 DOI: 10.1042/0264-6021:3570329] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
7B2 is an acidic protein residing in the secretory granules of neuroendocrine cells. Its sequence has been elucidated in many phyla and species. It shows high similarity among mammals. A Pro-Pro-Asn-Pro-Cys-Pro polyproline motif is its most conserved feature, being carried by both vertebrate and invertebrate sequences. It is biosynthesized as a precursor protein that is cleaved into an N-terminal fragment and a C-terminal peptide. In neuroendocrine cells, 7B2 functions as a specific chaperone for the proprotein convertase (PC) 2. Through the sequence around its Pro-Pro-Asn-Pro-Cys-Pro motif, it binds to an inactive proPC2 and facilitates its transport from the endoplasmic reticulum to later compartments of the secretory pathway where the zymogen is proteolytically matured and activated. Its C-terminal peptide can inhibit PC2 in vitro and may contribute to keep the enzyme transiently inactive in vivo. The PC2-7B2 model defines a new neuroendocrine paradigm whereby proteolytic activation of prohormones and proneuropeptides in the secretory pathway is spatially and temporally regulated by the dynamics of interactions between converting enzymes and their binding proteins. Interestingly, unlike PC2-null mice, which are viable, 7B2-null mutants die early in life from Cushing's disease due to corticotropin ('ACTH') hypersecretion by the neurointermediate lobe, suggesting a possible involvement of 7B2 in secretory granule formation and in secretion regulation. The mechanism of this regulation is yet to be elucidated. 7B2 has been shown to be a good marker of several neuroendocrine cell dysfunctions in humans. The possibility that anomalies in its structure and expression could be aetiological causes of some of these dysfunctions warrants investigation.
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Affiliation(s)
- M Mbikay
- Diseases of Aging Program, Ottawa Health Research Institute, Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada Y1K 4K9.
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Stark M, Danielsson O, Griffiths WJ, Jörnvall H, Johansson J. Peptide repertoire of human cerebrospinal fluid: novel proteolytic fragments of neuroendocrine proteins. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 754:357-67. [PMID: 11339279 DOI: 10.1016/s0378-4347(00)00628-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polypeptides in human cerebrospinal fluid (CSF), isolated by phase separation in chloroform-methanol-water and reversed-phase HPLC, were characterised by sequence analysis and mass spectrometry. This identified the presence of peptide fragments of testican, neuroendocrine specific protein VGF, neuroendocrine protein 7B2, chromogranin B/secretogranin I, chromogranin A, osteopontin, IGF-II E-peptide and proenkephalin. The majority of these fragments were generated by proteolysis at dibasic sites, suggesting that they are derived by activities related to prohormone convertase(s). Several of the fragments have previously not been detected, and their functions in CSF or elsewhere are unknown. A characteristic feature of all these fragments is a very high content of acidic residues, in particular glutamic acid. In addition to the fragments of neuroendocrine proteins, endothelin-binding receptor-like protein 2, ribonuclease 1, IGF-binding protein 6, albumin, alpha1-acid glycoprotein 1, prostaglandin-H2 D-isomerase, apolipoprotein A1, transthyretin, beta2-microglobulin, ubiquitin, fibrinopeptide A, and C4A anaphylatoxin were found.
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Affiliation(s)
- M Stark
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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García-Caballero A, Gallego R, García-Caballero T, Fraga M, Blanco M, Fernández-Redondo V, Beiras A. Cellular and subcellular distribution of 7B2 in porcine Merkel cells. Anat Rec (Hoboken) 1997; 248:159-63. [PMID: 9185981 DOI: 10.1002/(sici)1097-0185(199706)248:2<159::aid-ar2>3.0.co;2-o] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Merkel cells are neuroendocrine cells located in the skin and oral mucosa of various mammalian species. These cells express multiple peptides as well as serotonin. Although the precise function of Merkel cells is still unknown, different studies support its role as mechano-electric transducer. 7B2 granin (secretogranin V) is a polypeptide isolated from the pituitary gland and present in the dense-cored granules of neuronal and paraneuronal cells. METHODS The expression of the 7B2 in Merkel cells of pig snout skin was analysed by immunohistochemical techniques. The streptavidin-biotin peroxidase complex procedure was employed for light microscopy. A postembedding method using immunoglobulin-colloidal gold complexes was employed for the ultrastructural studies. RESULTS Immunoreactivity for 7B2 was observed in virtually all Merkel cells, both in epidermis and vibrissae. The immunostaining was shown in the basal side of cytoplasms where neuroendocrine granules were accumulated. Immunoelectron microscopy allowed us to demonstrate that 7B2 labelling was located on the electrondense granules. Nuclei and epidermal nerve terminals associated with merkel cells did not show immunoreactivity. CONCLUSIONS The polypeptide 7B2 is present in the dense-cored granules of Merkel cells. This result is consistent with the possible role for 7B2 in secretory granules' processing. To our knowledge this is the first evidence of 7B2 protein in Merkel cells.
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Affiliation(s)
- A García-Caballero
- Department of Morphological Sciences, School of Medicine-Hospital General de Galicia, University of Santiago, Santiago de Compostela, Spain
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11
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Braks JA, Van Horssen AM, Martens GJ. Dissociation of the complex between the neuroendocrine chaperone 7B2 and prohormone convertase PC2 is not associated with proPC2 maturation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:505-10. [PMID: 8681965 DOI: 10.1111/j.1432-1033.1996.0505z.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
7B2 is a highly conserved neuroendocrine protein that is associated with the proform of the prohormone convertase PC2 in the early stages of the secretory pathway in intermediate pituitary cells of Xenopus laevis. Subsequent processing of 7B2 and dissociation of the 7B2/proPC2 complex is thought to be associated with the conversion of proPC2 to the mature enzyme. Here, we report that, in both Xenopus and mouse intermediate cells, proPC2 maturation does not take place when the proenzyme is associated with the 7B2 precursor and that, in contrast to the previous notion, dissociation of the complex between proPC2 and the N-terminal 7B2 fragment precedes, and is thus not directly linked to, proPC2 maturation. In vitro, conversion of newly synthesized proPC2 was efficiently blocked by recombinant 7B2 and studies with truncation mutants indicated that a short segment in the C-terminal region of 7B2 is necessary and sufficient for this inhibitory effect. Our results indicate that, after 7B2 precursor processing and dissociation of the N-terminal fragment, the C-terminal fragment of 7B2 may remain associated with proPC2, thereby preventing autocatalytic conversion of the proenzyme until the appropriate site for activation in the secretory pathway is reached.
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Affiliation(s)
- J A Braks
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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12
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Braks JA, Broers CA, Danger JM, Martens GJ. Structural organization of the gene encoding the neuroendocrine chaperone 7B2. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 236:60-7. [PMID: 8617287 DOI: 10.1111/j.1432-1033.1996.00060.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The neuroendocrine-specific polypeptide 7B2 is a constituent of the regulated secretary pathway. Recently, 7B2 was found to function as a molecular chaperone for prohormone convertase PC2. This report describes the genomic organization of the 7B2 gene which consists of six exons. Exon I corresponds to the 5'-untranslated mRNA region, while exons 2 and 3 encode the signal peptide and the amino-terminal half of the 7B2 protein that is distantly related to a subclass of molecular chaperones. The carboxy-terminal half of 7B2, responsible for its inhibitory action on PC2, is encoded by exons 4-6. Primer-extension analysis showed that the human 7B2 gene is transcribed from multiple transcription-initiation sites. The human 7B2 gene promoter contains a cAMP-responsive element, an AP-1 site, and several Pit-1/GHF-1-binding domains and heat-shock-element-like sequences but no obvious TATA or CAAT boxes. Of further interest is the finding of two DNA elements which are common to the promoter regions of the 7B2 gene and other genes selectively expressed in neuroendocrine tissues.
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Affiliation(s)
- J A Braks
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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Sharp-Baker HE, Peute J, Diederen JHB, Brokken L. Origin and destination of globules and irregular masses in the gonadotropin cells from the pituitary of the African catfish, Clarias gariepinus: a morphological study. Cell Tissue Res 1995. [DOI: 10.1007/bf00304516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Seldeslagh KA, Lauweryns JM. Spatial and temporal distribution of 7B2 in the pulmonary diffuse neuroendocrine system of the cat. Neurosci Lett 1995; 188:85-8. [PMID: 7792063 DOI: 10.1016/0304-3940(95)11402-i] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The postnatal developmental profile of the presence of 7B2 was studied immunocytochemically in the pulmonary diffuse neuroendocrine system of the cat. Labelling was found in neuroepithelial bodies (NEB) but not in solitary neuroendocrine cells. The identity of NEB was confirmed on adjacent serial sections by the immunostaining for protein gene product 9.5, a pan-neuroendocrine marker. The first 3 weeks after birth 7B2 stained NEB were most abundant with a subsequent decline thereafter. The positive correlation between the variation of 7B2 immunoreactivity and number of NEB suggests an important role for 7B2 in NEB.
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Affiliation(s)
- K A Seldeslagh
- Catholic University of Louvain, Faculty of Medicine, Laboratory for Histopathology, Belgium
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15
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Seldeslagh KA, Lauweryns JM. 7B2 expression in intrapulmonary neuroepithelial bodies: immunocytochemical detection and colocalization with serotonin and calcitonin gene-related peptide. REGULATORY PEPTIDES 1994; 53:223-36. [PMID: 7846298 DOI: 10.1016/0167-0115(94)90171-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In this study, the occurrence of 7B2, a highly conserved pituitary protein present in many neuroendocrine tissues and tumors, was investigated for the first time in the neuroendocrine cells (NEC) and neuroepithelial bodies (NEB) of hamster, rat and cat lung, as well as its colocalization with serotonin (5-HT) and calcitonin gene-related peptide (CGRP). Bouin fixed and wax embedded lung tissue was serially cut and immunoreactive sites for 7B2, 5-HT and CGRP were demonstrated on adjacent sections with polyclonal rabbit antibodies, using the streptavidin-biotin peroxidase method. 7B2 immunostained NEB were numerous in the intrapulmonary airways and the alveolar parenchyma, always representing a subpopulation of CGRP labelled NEB, but outnumbering those containing 5-HT. NEC, on the other hand, were only immunoreactive for CGRP and 5-HT. Our results suggest that mammalian NEB are storehouses of heterogenous bioactive substances, which may be important components in the development of bronchopulmonary tumors. Moreover, the ubiquitous presence of 7B2 in NEB supports the idea of a pre- and/or post-exocytotic role in the cellular secretory processes while the lack of 7B2 immunoreactivity in NEC might indicate a distinct function for each of both neuroendocrine cell types.
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Affiliation(s)
- K A Seldeslagh
- Katholieke Universiteit Leuven, Faculteit Geneeskunde, Laboratorium voor Histopathologie I, Belgium
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16
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Braks JA, Martens GJ. 7B2 is a neuroendocrine chaperone that transiently interacts with prohormone convertase PC2 in the secretory pathway. Cell 1994; 78:263-73. [PMID: 7913882 DOI: 10.1016/0092-8674(94)90296-8] [Citation(s) in RCA: 173] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The neuroendocrine polypeptide 7B2 is a highly conserved secretory protein selectively present in prohormone-producing cells equipped with a regulated secretory pathway. We find that the amino-terminal half of 7B2 is distantly related to chaperonins, a subclass of molecular chaperones. When incubated in vitro with newly synthesized pituitary proteins, recombinant 7B2 specifically associates with prohormone convertase PC2. Metabolic cell labeling combined with coimmunoprecipitation studies showed that, in vivo, the precursor form of 7B2 interacts with the proform of PC2. Pulse-chase analysis revealed that this association is transient in that it commences early in the secretory pathway, while dissociation in the later stages appears to coincide with the cleavages of 7B2, proPC2, and prohormone. Our results suggest that 7B2 is a novel type of molecular chaperone preventing premature activation of proPC2 in the regulated secretory pathway.
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Affiliation(s)
- J A Braks
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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17
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The neuroendocrine precursor 7B2 is a sulfated protein proteolytically processed by a ubiquitous furin-like convertase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32164-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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18
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Martens GJ, Braks JA, Eib DW, Zhou Y, Lindberg I. The neuroendocrine polypeptide 7B2 is an endogenous inhibitor of prohormone convertase PC2. Proc Natl Acad Sci U S A 1994; 91:5784-7. [PMID: 8016065 PMCID: PMC44081 DOI: 10.1073/pnas.91.13.5784] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The subtilisin-like prohormone convertase PC2 and the polypeptide 7B2 (an intracellularly cleaved protein of unknown function) are both selectively present in the regulated secretory pathway of neurons and endocrine cells. Here we demonstrate that intact recombinant 7B2 is a potent inhibitor of PC2 and prevents proPC2 cleavage in vitro, whereas the 7B2 cleavage product is virtually inactive. The PC2-related proteinase PC1/PC3 is not inhibited by 7B2. Furthermore, the carboxyl-terminal half of the 7B2 protein sequence is distantly related to the so-called potato inhibitor I family (which includes subtilisin inhibitors). Our findings indicate that 7B2 is a physiological inhibitor of PC2 and may provide alternative avenues for the manipulation of peptide hormone levels.
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Affiliation(s)
- G J Martens
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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19
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Dillen L, Miserez B, Claeys M, Aunis D, De Potter W. Posttranslational processing of proenkephalins and chromogranins/secretogranins. Neurochem Int 1993; 22:315-52. [PMID: 8457770 DOI: 10.1016/0197-0186(93)90016-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Posttranslational processing of peptide-precursors is nowadays believed to play an important role in the functioning of neurons and endocrine cells. Both proenkephalins and chromogranins/secretogranins are considered as precursor molecules in these tissues, resulting in posttranslationally formed degradation products with potential biological activities. Among the proteins and peptides of neuronal and endocrine secretory granules, the enkephalins and enkephalin-containing peptides have been most extensively studied. The characterization of the post-translationally formed degradation products of the proenkephalins have enabled the understanding of their processing pathway. Chromogranins/secretogranins represent a group of acidic glycoproteins, contained within hormone storage granules. The biochemistry, biogenesis and molecular properties of these proteins have already been studied for 25 years. The chromogranins/secretogranins have a widespread distribution throughout the neuroendocrine system, the adrenal medullary chromaffin granules being the major source of these storage components. Recent data provide evidence for a precursor role for all members of the chromogranins/secretogranins family although also several other functions have been proposed. In this review, some of the methods applied to study proteolytic processing are described. In addition, the posttranslational processing of chromogranins/secretogranins and proenkephalins, especially the biochemical aspects, will be discussed and compared. Recent exciting developments on the generation and identification of potential physiologically active fragments will be covered.
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Affiliation(s)
- L Dillen
- Department of Pharmaceutical Sciences, University of Antwerp, UIA, Belgium
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20
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Day JR, Min BH, Laping NJ, Martin G, Osterburg HH, Finch CE. New mRNA probes for hippocampal responses to entorhinal cortex lesions in the adult male rat: a preliminary report. Exp Neurol 1992; 117:97-9. [PMID: 1618292 DOI: 10.1016/0014-4886(92)90117-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Three new mRNA responses were found in the hippocampus of the adult male rat after entorhinal cortex lesions (ECL) that induce synaptic reorganization. Hippocampus cDNA libraries were screened by a subtractive hybridization strategy designed to detect ECL-induced mRNAs. Partial sequencing showed clones with similarities to mouse vimentin, ferritin, and polypeptide 7B-2. A sequence similar to mouse SNAP-25 sequence was also detected. Using a mouse SNAP-25 probe, rat SNAP-25 mRNA increased in the hippocampus after ECL.
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Affiliation(s)
- J R Day
- Neurogerontology Division, Andrus Gerontology Center, Los Angeles, California
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21
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Lassmann H, Weiler R, Fischer P, Bancher C, Jellinger K, Floor E, Danielczyk W, Seitelberger F, Winkler H. Synaptic pathology in Alzheimer's disease: immunological data for markers of synaptic and large dense-core vesicles. Neuroscience 1992; 46:1-8. [PMID: 1594095 DOI: 10.1016/0306-4522(92)90003-k] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have analysed several markers for small synaptic vesicles (synaptin-synaptophysin, p65 and SV2) and large dense-core vesicles (chromogranin A, secretogranin II/chromogranin C) in the brains of patients with Alzheimer's disease, and normal controls by immunoblotting and immunohistochemistry. In comparison to age-matched controls the levels of all three synaptic vesicle markers were decreased in temporal cortex of Alzheimer patients. On the other hand, the levels of chromogranin A were increased, and those of secretogranin II lowered. This resulted in a significant increase of the ratios of chromogranin A to synaptophysin, p65 or SV2 and of that for chromogranin A to secretogranin II. These increases were significantly correlated to clinical severity of dementia and extent of neuropathological changes. By immunohistochemistry a high percentage of senile plaques was found to contain chromogranin A-reactive dystrophic neurites, whereas synaptophysin reactivity within plaques was rare. These results indicate that the number of synaptic vesicles is lowered in Alzheimer's disease, and that one component of large dense-core vesicles, i.e. chromogranin A, is elevated. We, thus, suggest that in Alzheimer's brain distinct changes occur for both types of synaptic organelles.
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Affiliation(s)
- H Lassmann
- Research Unit for Experimental Neuropathology, Austrian Academy of Sciences, Vienna
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22
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Iguchi H, Okeda T, Takaki R. Evidence for secretion of 7B2 by A- and B-cells of hamster pancreatic islets. REGULATORY PEPTIDES 1991; 36:407-14. [PMID: 1811274 DOI: 10.1016/0167-0115(91)90073-p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
7B2 is a neuroendocrine protein, and in the pancreatic islets the presence of 7B2 in A- and B-cells was immunohistochemically demonstrated. In order to examine 7B2 secretion by A- and B-cells of pancreatic islets, we prepared isolated hamster pancreatic islet cells as well as an A-cell-rich culture, and studied 7B2 secretion under certain stimulations. 7B2 was secreted by isolated hamster pancreatic islet cells. This secretion was stimulated by theophylline and arginine, but glucose had a weak effect on the 7B2 secretion. Such a response of 7B2 to the stimulations was different from that of insulin or glucagon. 7B2 secretion was also noted in the A-cell-rich culture. These results suggest that 7B2 is secreted by both A- and B-cells of the hamster pancreatic islets and its secretion is regulated under certain conditions.
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Affiliation(s)
- H Iguchi
- Department of Biochemistry, National Kyushu Cancer Center, Fukuoka, Japan
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23
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Ayoubi TA, van Duijnhoven HL, Coenen AJ, Jenks BG, Roubos EW, Martens GJ. Coordinated expression of 7B2 and alpha MSH in the melanotrope cells of Xenopus laevis. An immunocytochemical and in situ hybridization study. Cell Tissue Res 1991; 264:329-34. [PMID: 1652364 DOI: 10.1007/bf00313970] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
7B2 is a highly conserved protein present in many secretory cells. Using in situ hybridization techniques and immunocytochemistry, parameters concerning the biosynthesis and storage of the 7B2 protein were studied in the pituitary gland and median eminence of the clawed toad Xenopus laevis, in relation to the physiological process of background adaptation. 7B2-like immunoreactivity was present in the median eminence, in the neural and anterior pituitary lobes and, particularly, in the melanotrope cells of the intermediate pituitary lobe. In these cells, it coexisted with immunoreactivity to proopiomelanocortin (POMC)-derived alpha-melanocyte stimulating hormone (alpha MSH). The melanotropes of black-adapted animals had abundant 7B2-mRNA and POMC-mRNA; melanotropes of white-adapted toads had only low levels of these mRNAs. The presence of 7B2 in nerve terminals and endocrine cells supports the idea that the protein has a general function in the cellular secretory process. In X. laevis, 7B2 appears to be particularly associated with POMC and alpha MSH and, therefore, may play a role in the regulation of background adaptation.
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Affiliation(s)
- T A Ayoubi
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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24
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Ayoubi T, van Duijnhoven H, van de Ven W, Jenks B, Roubos E, Martens G. The neuroendocrine polypeptide 7B2 is a precursor protein. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55446-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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25
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Natori S, Iguchi H, Ohashi M, Nakao R, Bloom SR, Nawata H. Effect of octapeptide somatostatin analogue (SMS 201-995) on plasma 7B2 (a neuroendocrine polypeptide) levels in patients with acromegaly. Clin Endocrinol (Oxf) 1990; 32:49-55. [PMID: 2331811 DOI: 10.1111/j.1365-2265.1990.tb03749.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We studied the sequential changes of plasma levels of immunoreactive '7B2' (IR-7B2), a neuroendocrine polypeptide, after a subcutaneous injection of 50 micrograms of synthetic octapeptide somatostatin analogue (SMS 201-995) in seven patients with acromegaly due to GH-producing pituitary adenoma. Compared to the basal levels, mean plasma IR-7B2 and GH levels significantly decreased, until 5 and 10 h respectively after the administration of SMS 201-995. The mean (+/- SEM) nadir levels of plasma IR-7B2 and GH were 68.1 +/- 10.1 and 13.1 +/- 6.9%, respectively, compared to mean plasma levels before treatment (100%). Plasma IR-7B2 as well as GH levels did not change significantly when saline was administered subcutaneously to three acromegalic patients. In addition, plasma IR-7B2 levels did not change significantly after the administration of SMS 201-995 in normal subjects or in patients with primary hypothyroidism in whom SMS 201-995 induced a decrease of plasma TSH levels. These results strongly suggest that SMS 201-995 has an unequivocal suppressive effect on the synthesis and/or the secretion of 7B2 in human somatotroph adenoma cells.
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Affiliation(s)
- S Natori
- Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan
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26
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Suzuki Y, Sato S, Suzuki H, Namba J, Ohtake R, Hashigami Y, Suga S, Ishihara N, Shimoda S. Increased neuropeptide Y concentrations in cerebrospinal fluid from patients with aneurysmal subarachnoid hemorrhage. Stroke 1989; 20:1680-4. [PMID: 2531945 DOI: 10.1161/01.str.20.12.1680] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We investigated the possible relation between neuropeptides and cerebral vasoconstriction in samples of ventricular or cisternal cerebrospinal fluid from 14 patients with subarachnoid hemorrhage. Neuropeptide Y, calcitonin gene-related peptide, atrial natriuretic peptide, and pituitary polypeptide 7B2 were present in the cerebrospinal fluid of these patients. Concentrations of calcitonin gene-related peptide and 7B2 were not significantly different from those in control subjects, but that of atrial natriuretic peptide was significantly lower. Although the mean concentration of neuropeptide Y was not significantly higher than control, consecutive determinations showed an increase 6-11 days after the onset of subarachnoid hemorrhage. An initially high 7B2 concentration decreased gradually, although half the patients showed a second increase greater than 10 days after the onset. Considering the well-recognized vasoconstrictive effect of neuropeptide Y, it is possible that this increase in its concentration in the cerebrospinal fluid plays a role in the pathogenesis of the cerebral vasospasm that is often seen after subarachnoid hemorrhage.
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Affiliation(s)
- Y Suzuki
- Department of Endocrinology, Dokkyo University School of Medicine, Tochigi, Japan
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27
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van Duijnhoven HL, Ayoubi TA, Timmer ED, Braks AA, Roebroek AJ, Martens GJ, van de Ven WJ. Development of a monoclonal antibody against recombinant neuroendocrine 7B2 protein. FEBS Lett 1989; 255:372-6. [PMID: 2676606 DOI: 10.1016/0014-5793(89)81125-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mouse monoclonal antibody MON-100 was raised against the neuroendocrine protein 7B2 using bacterially produced hybrid proteins. In Western blot analysis, MON-100 reacted with 3 different 7B2 hybrid proteins and not with the respective carrier proteins. Furthermore, MON-100 was reactive with recombinant 7B2 cleaved from a hybrid protein. In an immunohistochemical study, MON-100 exhibited strong reactivity with the intermediate lobe of the Xenopus pituitary gland, a tissue previously shown to contain 7B2 mRNA. Using MON-100, immunoprecipitation analysis of newly synthesized proteins produced by in vitro incubated Xenopus neurointermediate lobes revealed the biosynthesis of a single protein of Mr 24 kDa, the expected size of the 7B2 protein. It appears, therefore, that the anti-7B2 monoclonal antibody MON-100 can be successfully used for Western blot analysis and immunohistochemical analysis as well as for immunoprecipitation experiments.
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28
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Iguchi H, Hara N, Hayashi I, Ohta M, Bloom SR, Chrétien M. Elevation of a novel pituitary protein (7B2) in the plasma in small cell carcinoma of the lung. EUROPEAN JOURNAL OF CANCER & CLINICAL ONCOLOGY 1989; 25:1225-32. [PMID: 2548871 DOI: 10.1016/0277-5379(89)90419-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
7B2 is a new protein isolated from human pituitary glands and distributed widely, particularly with high concentrations in the neuroendocrine tissues in the rat. We measured plasma 7B2 concentrations in 333 normal subjects, 20 patients with benign pulmonary disease and 111 patients with primary lung cancer (21 small cell carcinoma, 90 non-small cell carcinoma). A normal range for plasma 7B2 concentrations was defined as less than the mean + 3 S.D. value (110 pg/ml) based on plasma 7B2 concentrations in 333 normal subjects. Elevation of the plasma 7B2 concentration over the normal range was observed in 15 of 21 patients (71.4%) with small cell carcinoma, eight of 90 (8.9%) with non-small cell carcinoma and four of 20 (20%) with benign pulmonary disease. Plasma 7B2 concentrations correlated with the clinical course on chemotherapy in some patients with small cell carcinoma. Immunocytochemical studies revealed numerous 7B2-positive cells in the small cell carcinoma specimen, while 7B2 staining was not observed in the non-small cell carcinoma and the normal lung specimens. These findings suggest that 7B2 is secreted by the small cell carcinoma of the lung, which caused elevation of plasma 7B2 in these patients. 7B2 might be a possible plasma tumor marker for the small cell carcinoma of the lung.
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Affiliation(s)
- H Iguchi
- Department of Biochemistry, National Kyushu Cancer Center, Fukuoka, Japan
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29
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Martens GJ, Bussemakers MJ, Ayoubi TA, Jenks BG. The novel pituitary polypeptide 7B2 is a highly-conserved protein coexpressed with proopiomelanocortin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 181:75-9. [PMID: 2714283 DOI: 10.1111/j.1432-1033.1989.tb14695.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the amphibian intermediate pituitary gland the biosynthetic activity for production of the precursor protein proopiomelanocortin (POMC) can be physiologically manipulated; POMC synthesis is high in animals adapted to a black background and low in white-adapted animals. In order to study genes associated with POMC gene expression we applied a differential hybridization technique involving screening of a pituitary cDNA library with probes derived from RNA of inactive and physiologically activated intermediate pituitary cells of the amphibian Xenopus laevis. A differentially hybridizing Xenopus pituitary cDNA clone encoded the novel polypeptide 7B2. This Mr-21,000 secretory granule-associated protein of unknown function is shown to be highly conserved between Xenopus and human (83% amino acid sequence similarity). Conserved segments within the 7B2 structure included the N-terminal portion, three pairs of basic amino acids which are potential recognition sites for proteolytic enzymes, and three regions sharing similarity with putative GTP-binding domains. Levels of 7B2 mRNA were about 3% of POMC mRNA levels in Xenopus pituitary glands. In the intermediate pituitary the amount of both POMC and 7B2 mRNA was much higher in black-adapted toads than in white-adapted animals. These physiologically-induced changes in POMC and 7B2 mRNA levels were not found in the anterior pituitary. We conclude that the POMC and 7B2 genes are coexpressed and that modulation of the activity of these genes is tissue-specific.
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Affiliation(s)
- G J Martens
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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30
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Natori S, Iguchi H, Kurose S, Bloom SR, Nawata H. Age-related change in 7B2 (a novel pituitary polypeptide) concentrations in human cerebrospinal fluid. REGULATORY PEPTIDES 1988; 22:371-6. [PMID: 3187078 DOI: 10.1016/0167-0115(88)90113-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Concentrations of 7B2 (a novel pituitary polypeptide) immunoreactivity (7B2-IR) were measured using a specific 7B2 radioimmunoassay (RIA) in cerebrospinal fluids (CSFs) from 87 humans. The mean (+/- S.E.M.) concentration of 7B2-IR in CSF was 2022 +/- 68 pM and a statistically significant decrease with aging was observed in those concentrations (R = -0.28, t = 2.73, P less than 0.01), although it was not a strong relation based on the R-value. In the gel permeation chromatography of CSF on Sephadex G-100, a major peak with an apparent mol. wt. of 43 kDa (43K) and a minor peak with that of 11 kDa (11K) were observed.
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Affiliation(s)
- S Natori
- Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan
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31
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Abstract
Application of a differential hybridization technique led to the isolation of a human pituitary cDNA clone encoding the complete structure of the polypeptide 7B2. This protein of unknown function, which is sorted to secretory granules, appears to be present selectively in neurons and endocrine cells. The polypeptide chain of human 7B2, preceded by a cleaved signal peptide, comprises 185 amino acids (a calculated Mr of 20,793). Interesting features of the highly-conserved 7B2 structure include (i) a serine phosphorylation consensus sequence, (ii) the occurrence of three pairs of dibasic amino acids representing potential proteolytic cleavage sites and, in particular, (iii) the presence of three regions homologous to GTP-binding domains giving 7B2 structural characteristics of a GTP-binding protein.
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Affiliation(s)
- G J Martens
- Department of Animal Physiology, University of Nijmegen, The Netherlands
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32
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Iguchi H, Natori S, Ou Y, Nawata H, Kato K, Ibayashi H, Bloom SR. Plasma levels of 7B2 (a novel pituitary polypeptide) and its molecular forms in plasma and urine in patients with chronic renal failure: possible degradation by the kidney. REGULATORY PEPTIDES 1988; 21:263-70. [PMID: 3413294 DOI: 10.1016/0167-0115(88)90009-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Plasma immunoreactive (IR)-7B2 was measured in patients with chronic renal failure (CRF), using a specific radioimmunoassay. The mean (+/- S.E.M.) concentration of plasma IR-7B2 in CRF patients under hemodialysis (502 +/- 36 pg/ml, n = 27) was significantly higher than that in normal subjects (men, 52.9 +/- 1.7 pg/ml (n = 179); women, 55.8 +/- 1.3 pg/ml (n = 198]. Significant correlations between plasma levels of IR-7B2 and those of blood urea nitrogen, creatinine and beta 2-microglobulin were evident in non-dialyzed CRF patients. In the analyses of pooled plasma and urine obtained from normal subjects on gel permeation chromatography, a major peak of IR-7B2 was observed at an apparent molecular weight of 20,000 in the plasma, and at a position of a smaller molecular weight in the urine. These results suggest that 7B2 is degraded mainly in the kidney and that measurement of plasma 7B2 may serve as an appropriate tool for assessing renal function.
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Affiliation(s)
- H Iguchi
- Department of Biochemistry, National Kyushu Cancer Center, Fukuoka, Japan
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