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Barker E, Milburn AE, Helassa N, Hammond DE, Sanchez-Soriano N, Morgan A, Barclay JW. Proximity labelling reveals effects of disease-causing mutation on the DNAJC5/cysteine string protein α interactome. Biochem J 2024; 481:BCJ20230319. [PMID: 38193346 PMCID: PMC10903463 DOI: 10.1042/bcj20230319] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 01/05/2024] [Accepted: 01/09/2024] [Indexed: 01/10/2024]
Abstract
Cysteine string protein α (CSPα), also known as DNAJC5, is a member of the DnaJ/Hsp40 family of co-chaperones. The name derives from a cysteine-rich domain, palmitoylation of which enables localization to intracellular membranes, notably neuronal synaptic vesicles. Mutations in the DNAJC5 gene that encodes CSPα cause autosomal dominant, adult-onset neuronal ceroid lipofuscinosis (ANCL), a rare neurodegenerative disease. As null mutations in CSP-encoding genes in flies, worms and mice similarly result in neurodegeneration, CSP is evidently an evolutionarily conserved neuroprotective protein. However, the client proteins that CSP chaperones to prevent neurodegeneration remain unclear. Traditional methods for identifying protein-protein interactions such as yeast 2-hybrid and affinity purification approaches are poorly suited to CSP, due to its requirement for membrane anchoring and its tendency to aggregate after cell lysis. Therefore, we employed proximity labelling, which enables identification of interacting proteins in situ in living cells via biotinylation. Neuroendocrine PC12 cell lines stably expressing wild type or L115R ANCL mutant CSP constructs fused to miniTurbo were generated; then the biotinylated proteomes were analysed by liquid chromatographymass spectrometry (LCMS) and validated by western blotting. This confirmed several known CSP-interacting proteins, such as Hsc70 and SNAP-25, but also revealed novel binding proteins, including STXBP1/Munc18-1. Interestingly, some protein interactions (such as Hsc70) were unaffected by the L115R mutation, whereas others (including SNAP-25 and STXBP1/Munc18-1) were inhibited. These results define the CSP interactome in a neuronal model cell line and reveal interactions that are affected by ANCL mutation and hence may contribute to the neurodegeneration seen in patients.
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Affiliation(s)
- Eleanor Barker
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Amy E. Milburn
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Nordine Helassa
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Dean E. Hammond
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Natalia Sanchez-Soriano
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Alan Morgan
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Jeff W. Barclay
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
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2
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Srivastava A, Singh S, Pandey A, Kumar D, Rajpurohit CS, Khanna VK, Pant AB. Secretome of Differentiated PC12 Cells Enhances Neuronal Differentiation in Human Mesenchymal Stem Cells Via NGF-Like Mechanism. Mol Neurobiol 2018. [PMID: 29527653 DOI: 10.1007/s12035-018-0981-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The secretome-mediated responses over cellular physiology are well documented. Stem cells have been ruling the field of secretomics and its role in regenerative medicine since the past few years. However, the mechanistic aspects of secretome-mediated responses and the role of other cells in this area remain somewhat elusive. Here, we investigate the effects of secretome-enriched conditioned medium (CM) of neuronally differentiated PC12 cells on the neuronal differentiation of human mesenchymal stem cells (hMSCs). The exposure to CM at a ratio of 1:1 (CM: conditioned medium of PC12 cells) led to neuronal induction in hMSCs. This neuronal induction was compared with a parallel group of cells exposed to nerve growth factor (NGF). There was a marked increase in neurite length and expression of neuronal markers (β-III tubulin, neurofilament-M (NF-M), synaptophysin, NeuN in exposed hMSCs). Experimental group co-exposed to NGF and CM showed an additive response via MAPK signaling and directed the cells particularly towards cholinergic lineage. The ability of CM to enhance the neuronal properties of stem cells could aid in their rapid differentiation into neuronal subtypes in case of stem cell transplantation for neuronal injuries, thus broadening the scope of non-stem cell-based applications in the area of secretomics.
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Affiliation(s)
- A Srivastava
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India
| | - S Singh
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India.,Academy of Scientific and Innovative Research, CSIR-IITR Campus, Lucknow, India
| | - A Pandey
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India
| | - D Kumar
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India.,Academy of Scientific and Innovative Research, CSIR-IITR Campus, Lucknow, India
| | - C S Rajpurohit
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India.,Academy of Scientific and Innovative Research, CSIR-IITR Campus, Lucknow, India
| | - V K Khanna
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India.,Academy of Scientific and Innovative Research, CSIR-IITR Campus, Lucknow, India
| | - A B Pant
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), MG Marg, Lucknow, Uttar Pradesh, -226001, India. .,Academy of Scientific and Innovative Research, CSIR-IITR Campus, Lucknow, India.
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3
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Sahu BS, Manna PT, Edgar JR, Antrobus R, Mahata SK, Bartolomucci A, Borner GHH, Robinson MS. Role of clathrin in dense core vesicle biogenesis. Mol Biol Cell 2017; 28:2676-2685. [PMID: 28814506 PMCID: PMC5620375 DOI: 10.1091/mbc.e16-10-0742] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 07/13/2017] [Accepted: 08/07/2017] [Indexed: 11/11/2022] Open
Abstract
The dense core vesicles (DCVs) of neuroendocrine cells are a rich source of bioactive molecules such as peptides, hormones, and neurotransmitters, but relatively little is known about how they are formed. Using fractionation profiling, a method that combines subcellular fractionation with mass spectrometry, we identified ∼1200 proteins in PC12 cell vesicle-enriched fractions, with DCV-associated proteins showing distinct profiles from proteins associated with other types of vesicles. To investigate the role of clathrin in DCV biogenesis, we stably transduced PC12 cells with an inducible short hairpin RNA targeting clathrin heavy chain, resulting in ∼85% protein loss. DCVs could still be observed in the cells by electron microscopy, but mature profiles were approximately fourfold less abundant than in mock-treated cells. By quantitative mass spectrometry, DCV-associated proteins were found to be reduced approximately twofold in clathrin-depleted cells as a whole and approximately fivefold in vesicle-enriched fractions. Our combined data sets enabled us to identify new candidate DCV components. Secretion assays revealed that clathrin depletion causes a near-complete block in secretagogue-induced exocytosis. Taken together, our data indicate that clathrin has a function in DCV biogenesis beyond its established role in removing unwanted proteins from the immature vesicle.
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Affiliation(s)
- Bhavani S Sahu
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Paul T Manna
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - James R Edgar
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Sushil K Mahata
- Department of Medicine, Veterans Affairs San Diego Healthcare System, San Diego, CA 92161.,Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Alessandro Bartolomucci
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455
| | - Georg H H Borner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Margaret S Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
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Lin Q, Mao Y, Song Y, Huang D. MicroRNA‑34a induces apoptosis in PC12 cells by reducing B‑cell lymphoma 2 and sirtuin‑1 expression. Mol Med Rep 2015; 12:5709-14. [PMID: 26252661 PMCID: PMC4581806 DOI: 10.3892/mmr.2015.4185] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 07/03/2015] [Indexed: 12/14/2022] Open
Abstract
MicroRNA-34a (miR-34a) is a direct target of p53 and was reported to induce cell cycle arrest, apoptosis and senescence. Inhibition of the NAD-dependent deacetylase sirtuin-1 (SIRT1) by miR-34a leads to an increase in acetylated p53, which promotes cell apoptosis. B-cell lymphoma 2 (Bcl-2) is also involved in apoptosis, and was originally characterized with respect to its role in controlling outer mitochondrial membrane integrity. The effect of miR-34a in PC12 cells has not yet been reported. In the present study, it was hypothesized that Bcl-2 and SIRT1 may be critical downstream targets of miR-34a that participate in apoptosis induction. miR-34a mimics and inhibitors were transfected into PC12 cells, and the apoptosis and proliferation rates were compared between groups. It was demonstrated that induction of miR-34a promotes apoptosis and senescence, inhibits proliferation, and leads to marked alterations in SIRT1, Bcl-12 and acetyl (ac)-p53 expression. These data indicate that miR-34a may be important in neuropathy.
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Affiliation(s)
- Qiang Lin
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yurong Mao
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yunlin Song
- Intensive Care Unit, The First Affiliated Hospital of Xinjiang Medical University, Ürümqi, Xinjiang Uyghur Autonomous Region 830011, P.R. China
| | - Dongfeng Huang
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
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Guizzetti L, McGirr R, Dhanvantari S. Two dipolar α-helices within hormone-encoding regions of proglucagon are sorting signals to the regulated secretory pathway. J Biol Chem 2014; 289:14968-80. [PMID: 24727476 DOI: 10.1074/jbc.m114.563684] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Proglucagon is expressed in pancreatic α cells, intestinal L cells, and some hypothalamic and brainstem neurons. Tissue-specific processing of proglucagon yields three major peptide hormones as follows: glucagon in the α cells and glucagon-like peptides (GLP)-1 and -2 in the L cells and neurons. Efficient sorting and packaging into the secretory granules of the regulated secretory pathway in each cell type are required for nutrient-regulated secretion of these proglucagon-derived peptides. Our previous work suggested that proglucagon is directed into granules by intrinsic sorting signals after initial processing to glicentin and major proglucagon fragment (McGirr, R., Guizzetti, L., and Dhanvantari, S. (2013) J. Endocrinol. 217, 229-240), leading to the hypothesis that sorting signals may be present in multiple domains. In the present study, we show that the α-helices within glucagon and GLP-1, but not GLP-2, act as sorting signals by efficiently directing a heterologous secretory protein to the regulated secretory pathway. Biophysical characterization of these peptides revealed that glucagon and GLP-1 each encode a nonamphipathic, dipolar α-helix, whereas the helix in GLP-2 is not dipolar. Surprisingly, glicentin and major proglucagon fragment were sorted with different efficiencies, thus providing evidence that proglucagon is first sorted to granules prior to processing. In contrast to many other prohormones in which sorting is directed by ordered prodomains, the sorting determinants of proglucagon lie within the ordered hormone domains of glucagon and GLP-1, illustrating that each prohormone has its own sorting "signature."
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Affiliation(s)
| | - Rebecca McGirr
- the Metabolism/Diabetes and Imaging Programs, Lawson Health Research Institute, London, Ontario N6A 4V2, Canada
| | - Savita Dhanvantari
- From the Departments of Medical Biophysics, the Metabolism/Diabetes and Imaging Programs, Lawson Health Research Institute, London, Ontario N6A 4V2, Canada Pathology, and Medicine, University of Western Ontario, London, Ontario N6A 3K7 and
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Hogk I, Kaufmann M, Finkelmeier D, Rupp S, Burger-Kentischer A. An In Vitro HSV-1 Reactivation Model Containing Quiescently Infected PC12 Cells. Biores Open Access 2013; 2:250-7. [PMID: 23914331 PMCID: PMC3731678 DOI: 10.1089/biores.2013.0019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Advances in the understanding of the infection and reactivation process of herpes simplex type 1 (HSV-1) are generally gained by monolayer cultures or extensive and cost-intensive animal models. So far, no reliable in vitro skin model exists either to investigate the molecular mechanisms involved in controlling latency and virus reactivation or to test pharmaceuticals. Here we demonstrate the first in vitro HSV-1 reactivation model generated by using the human keratinocyte cell line HaCaT grown on a collagen substrate containing primary human fibroblasts. We integrated the unique feature of a quiescently infected neuronal cell line, the rat pheochromocytoma line PC12, within the dermal layer of the three-dimensional skin equivalent. Transmission electron microscopy, a cell-based TCID50 assay, and polymerase chain reaction analysis were used to verify cell latency. Thereby viral DNA could be detected, whereas extracellular as well as intracellular virus activity could not be found. Further, the infected PC12 cells show no spontaneous reactivation within the in vitro skin equivalent. In order to simulate a physiologically comparable HSV-1 infection, we achieved a specific and pointed reactivation of quiescently HSV-1 infected PC12 cells by UVB irradiation at 1000 mJ/cm2.
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Affiliation(s)
- Ina Hogk
- Institute for Interfacial Engineering and Plasma Technology, University of Stuttgart , Stuttgart, Germany
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7
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Arsenault J, Ferrari E, Niranjan D, Cuijpers SAG, Gu C, Vallis Y, O'Brien J, Davletov B. Stapling of the botulinum type A protease to growth factors and neuropeptides allows selective targeting of neuroendocrine cells. J Neurochem 2013; 126:223-33. [PMID: 23638840 PMCID: PMC3758956 DOI: 10.1111/jnc.12284] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 04/16/2013] [Accepted: 04/24/2013] [Indexed: 01/12/2023]
Abstract
Precise cellular targeting of macromolecular cargos has important biotechnological and medical implications. Using a recently established ‘protein stapling’ method, we linked the proteolytic domain of botulinum neurotoxin type A (BoNT/A) to a selection of ligands to target neuroendocrine tumor cells. The botulinum proteolytic domain was chosen because of its well-known potency to block the release of neurotransmitters and hormones. Among nine tested stapled ligands, the epidermal growth factor was able to deliver the botulinum enzyme into pheochromocytoma PC12 and insulinoma Min6 cells; ciliary neurotrophic factor was effective on neuroblastoma SH-SY5Y and Neuro2A cells, whereas corticotropin-releasing hormone was active on pituitary AtT-20 cells and the two neuroblastoma cell lines. In neuronal cultures, the epidermal growth factor- and ciliary neurotrophic factor-directed botulinum enzyme targeted distinct subsets of neurons whereas the whole native neurotoxin targeted the cortical neurons indiscriminately. At nanomolar concentrations, the retargeted botulinum molecules were able to inhibit stimulated release of hormones from tested cell lines suggesting their application for treatments of neuroendocrine disorders.
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Affiliation(s)
- Jason Arsenault
- MRC Laboratory of Molecular Biology, Neurobiology, Cambridge, UK
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8
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Polman JAE, Welten JE, Bosch DS, de Jonge RT, Balog J, van der Maarel SM, de Kloet ER, Datson NA. A genome-wide signature of glucocorticoid receptor binding in neuronal PC12 cells. BMC Neurosci 2012; 13:118. [PMID: 23031785 PMCID: PMC3519639 DOI: 10.1186/1471-2202-13-118] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 09/24/2012] [Indexed: 12/22/2022] Open
Abstract
Background Glucocorticoids, secreted by the adrenals in response to stress, profoundly affect structure and plasticity of neurons. Glucocorticoid action in neurons is mediated by glucocorticoid receptors (GR) that operate as transcription factors in the regulation of gene expression and either bind directly to genomic glucocorticoid response elements (GREs) or indirectly to the genome via interactions with bound transcription factors. These two modes of action, respectively called transactivation and transrepression, result in the regulation of a wide variety of genes important for neuronal function. The objective of the present study was to identify genome-wide glucocorticoid receptor binding sites in neuronal PC12 cells using Chromatin ImmunoPrecipitation combined with next generation sequencing (ChIP-Seq). Results In total we identified 1183 genomic binding sites of GR, the majority of which were novel and not identified in other ChIP-Seq studies on GR binding. More than half (58%) of the binding sites contained a GRE. The remaining 42% of the GBS did not harbour a GRE and therefore likely bind GR via an intermediate transcription factor tethering GR to the DNA. While the GRE-containing binding sites were more often located nearby genes involved in general cell functions and processes such as apoptosis, cell motion, protein dimerization activity and vasculature development, the binding sites without a GRE were located nearby genes with a clear role in neuronal processes such as neuron projection morphogenesis, neuron projection regeneration, synaptic transmission and catecholamine biosynthetic process. A closer look at the sequence of the GR binding sites revealed the presence of several motifs for transcription factors that are highly divergent from those previously linked to GR-signaling, including Gabpa, Prrx2, Zfp281, Gata1 and Zbtb3. These transcription factors may represent novel crosstalk partners of GR in a neuronal context. Conclusions Here we present the first genome-wide inventory of GR-binding sites in a neuronal context. These results provide an exciting first global view into neuronal GR targets and the neuron-specific modes of GR action and potentially contributes to our understanding of glucocorticoid action in the brain.
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Affiliation(s)
- J Annelies E Polman
- Division of Medical Pharmacology, Leiden/Amsterdam Center for Drug Research, Leiden University Medical Center, Leiden, 2333 CC, The Netherlands
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Hashikawa-Hobara N, Chan NYK, Levi R. Histamine 3 receptor activation reduces the expression of neuronal angiotensin II type 1 receptors in the heart. J Pharmacol Exp Ther 2011; 340:185-91. [PMID: 22011436 DOI: 10.1124/jpet.111.187765] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In severe myocardial ischemia, histamine 3 (H₃) receptor activation affords cardioprotection by preventing excessive norepinephrine release and arrhythmias; pivotal to this action is the inhibition of neuronal Na⁺/H⁺ exchanger (NHE). Conversely, angiotensin II, formed locally by mast cell-derived renin, stimulates NHE via angiotensin II type 1 (AT₁) receptors, facilitating norepinephrine release and arrhythmias. Thus, ischemic dysfunction may depend on a balance between the NHE-modulating effects of H₃ receptors and AT₁ receptors. The purpose of this investigation was therefore to elucidate the H₃/AT₁ receptor interaction in myocardial ischemia/reperfusion. We found that H₃ receptor blockade with clobenpropit increased norepinephrine overflow and arrhythmias in Langendorff-perfused guinea pig hearts subjected to ischemia/reperfusion. This coincided with increased neuronal AT₁ receptor expression. NHE inhibition with cariporide prevented both increases in norepinephrine release and AT₁ receptor expression. Moreover, norepinephrine release and AT₁ receptor expression were increased by the nitric oxide (NO) synthase inhibitor N(G)-methyl-L-arginine and the protein kinase C activator phorbol myristate acetate. H₃ receptor activation in differentiated sympathetic neuron-like PC12 cells permanently transfected with H₃ receptor cDNA caused a decrease in protein kinase C activity and AT₁ receptor protein abundance. Collectively, our findings suggest that neuronal H₃ receptor activation inhibits NHE by diminishing protein kinase C activity. Reduced NHE activity sequentially causes intracellular acidification, increased NO synthesis, and diminished AT₁ receptor expression. Thus, H₃ receptor-mediated NHE inhibition in ischemia/reperfusion not only opposes the angiotensin II-induced stimulation of NHE in cardiac sympathetic neurons, but also down-regulates AT₁ receptor expression. Cardioprotection ultimately results from the combined attenuation of angiotensin II and norepinephrine effects and alleviation of arrhythmias.
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Wei Z, Biswas N, Wang L, Courel M, Zhang K, Soler-Jover A, Taupenot L, O'Connor DT. A common genetic variant in the 3'-UTR of vacuolar H+-ATPase ATP6V0A1 creates a micro-RNA motif to alter chromogranin A processing and hypertension risk. ACTA ACUST UNITED AC 2011; 4:381-9. [PMID: 21558123 DOI: 10.1161/circgenetics.111.959767] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND The catecholamine release-inhibitor catestatin and its precursor chromogranin A (CHGA) may constitute "intermediate phenotypes" in the analysis of genetic risk for cardiovascular disease such as hypertension. Previously, the vacuolar H(+)-ATPase subunit gene ATP6V0A1 was found within the confidence interval for linkage with catestatin secretion in a genome-wide study, and its 3'-UTR polymorphism T+3246C (rs938671) was associated with both catestatin processing from CHGA and population blood pressure. We explored the molecular mechanism of this effect by experiments with transfected chimeric photoproteins in chromaffin cells. METHODS AND RESULTS Placing the ATP6V0A1 3'-UTR downstream of a luciferase reporter, we found that the C (variant) allele decreased overall gene expression. The 3'-UTR effect was verified by coupled in vitro transcription/translation of the entire/intact human ATP6V0A1 mRNA. Chromaffin granule pH, monitored by fluorescence of CHGA/EGFP chimera during vesicular H(+)-ATPase inhibition by bafilomycin A1, was more easily perturbed during coexpression of the ATP6V0A1 3'-UTR C-allele than the T-allele. After bafilomycin A1 treatment, the ratio of CHGA precursor to its catestatin fragments in PC12 cells was substantially diminished, though the qualitative composition of such fragments was not affected (on immunoblot or matrix-assisted laser desorption ionization (MALDI) mass spectrometry). Bafilomycin A1 treatment also decreased exocytotic secretion from the regulated pathway, monitored by a CHGA chimera tagged with embryonic alkaline phosphatase. 3'-UTR T+3246C created a binding motif for micro-RNA hsa-miR-637; cotransfection of hsa-miR-637 precursor or antagomir/inhibitor oligonucleotides yielded the predicted changes in expression of luciferase reporter/ATP6V0A1-3'-UTR plasmids varying at T+3246C. CONCLUSIONS The results suggest a series of events whereby ATP6V0A1 3'-UTR variant T+3246C functioned: ATP6V0A1 expression probably was affected through differential micro-RNA effects, altering vacuolar pH and consequently CHGA processing and exocytotic secretion.
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Affiliation(s)
- Zhiyun Wei
- Departments of Medicine and Pharmacology, Institute for Genomic Medicine, University of California at San Diego, the VA San Diego Healthcare System, La Jolla, USA
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11
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Courel M, Soler-Jover A, Rodriguez-Flores JL, Mahata SK, Elias S, Montero-Hadjadje M, Anouar Y, Giuly RJ, O'Connor DT, Taupenot L. Pro-hormone secretogranin II regulates dense core secretory granule biogenesis in catecholaminergic cells. J Biol Chem 2010; 285:10030-10043. [PMID: 20061385 PMCID: PMC2843166 DOI: 10.1074/jbc.m109.064196] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 12/16/2009] [Indexed: 11/06/2022] Open
Abstract
Processes underlying the formation of dense core secretory granules (DCGs) of neuroendocrine cells are poorly understood. Here, we present evidence that DCG biogenesis is dependent on the secretory protein secretogranin (Sg) II, a member of the granin family of pro-hormone cargo of DCGs in neuroendocrine cells. Depletion of SgII expression in PC12 cells leads to a decrease in both the number and size of DCGs and impairs DCG trafficking of other regulated hormones. Expression of SgII fusion proteins in a secretory-deficient PC12 variant rescues a regulated secretory pathway. SgII-containing dense core vesicles share morphological and physical properties with bona fide DCGs, are competent for regulated exocytosis, and maintain an acidic luminal pH through the V-type H(+)-translocating ATPase. The granulogenic activity of SgII requires a pH gradient along this secretory pathway. We conclude that SgII is a critical factor for the regulation of DCG biogenesis in neuroendocrine cells, mediating the formation of functional DCGs via its pH-dependent aggregation at the trans-Golgi network.
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Affiliation(s)
- Maïté Courel
- Department of Medicine, University of California San Diego, La Jolla, California 92093-0838.
| | - Alex Soler-Jover
- Department of Medicine, University of California San Diego, La Jolla, California 92093-0838
| | | | - Sushil K Mahata
- Department of Medicine, University of California San Diego, La Jolla, California 92093-0838; Veteran Affairs San Diego Healthcare System, San Diego, California 92093
| | - Salah Elias
- INSERM U982, University of Rouen, 76821 Mont-St.-Aignan Cedex, France
| | | | - Youssef Anouar
- INSERM U982, University of Rouen, 76821 Mont-St.-Aignan Cedex, France
| | - Richard J Giuly
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, California 92093
| | - Daniel T O'Connor
- Department of Medicine, University of California San Diego, La Jolla, California 92093-0838; Veteran Affairs San Diego Healthcare System, San Diego, California 92093.
| | - Laurent Taupenot
- Department of Medicine, University of California San Diego, La Jolla, California 92093-0838; Veteran Affairs San Diego Healthcare System, San Diego, California 92093.
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Inomoto C, Osamura RY. Formation of secretory granules by chromogranins. Med Mol Morphol 2009; 42:201-3. [PMID: 20033364 DOI: 10.1007/s00795-009-0472-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 10/05/2009] [Indexed: 11/28/2022]
Abstract
This review article covers the molecular mechanisms of secretory granule formation by chromogranin transfection. Recently, a few investigators have reported that the transfection of chromogranin A and B produces the structures of secretory granules. We used the GFP-chromogranin A transfection method to nonendocrine cells, COS-7 cells, which are not equipped with secretory granules. Despite the absence of endogenous secretory granules in nontransfected COS-7 cells, COS-7 cells transfected with chromogranin A contained granule-like structures in electron micrographs. The granules were composed of an outer limiting membrane with core structures that were interpreted as secretory granules. Human chromogranin A (CgA) labeled with 5-nm gold particles was present in several dense-core granules in our previous electron microscopy study. This review depicts the role of chromogranin A in the formation of secretory granules. It emphasizes the application of recently developed new technologies and the genesis of secretory granules.
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Affiliation(s)
- Chie Inomoto
- Department of Pathology, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan.
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Calì C, Marchaland J, Spagnuolo P, Gremion J, Bezzi P. Regulated exocytosis from astrocytes physiological and pathological related aspects. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 85:261-93. [PMID: 19607976 DOI: 10.1016/s0074-7742(09)85020-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Astrocytes have traditionally been considered ancillary, satellite cells of the nervous system. However, it is a very recent acquisition that glial cells generate signaling loops which are integral to the brain circuitry and participate, interactively with neuronal networks, in the processing of information. Such a conceptual breakthrough makes this field of investigation one of the hottest in neuroscience, as it calls for a revision of past theories of brain function as well as for new strategies of experimental exploration of brain function. Glial cells are electrically not excitable, and it was only the use of optical recording techniques together with calcium sensitive dyes, that allowed the chemical excitability of glial cells to become apparent. Studies using these new techniques have shown for the first time that glial cells are activated by surrounding synaptic activity and translate neuronal signals into their own calcium code. Intracellular calcium concentration([Ca2+]i) elevations in glial cells have then shown to underlie spatial transfer of information in the glial network, accompanied by release of chemical transmitters (gliotransmitters) such as glutamate and back-signaling to neurons. As a consequence, optical imaging techniques applied to cell cultures or intact tissue have become a state-of-the-art technology for studying glial cell signaling. The molecular mechanisms leading to release of "gliotransmitters," especially glutamate, from glia are under debate. Accumulating evidence clearly indicates that astrocytes secrete numerous transmitters by Ca(2+)-dependent exocytosis. This review will discuss the mechanisms underlying the release of chemical transmitters from astrocytes with a particular emphasis to the regulated exocytosis processes.
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Affiliation(s)
- Corrado Calì
- Department of Cellular Biology and Morphology (DBCM), Faculty of Medicine, University of Lausanne, rue du Bugnon 9, 1005 Lausanne, Switzerland
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Morrey C, Estephan R, Abbott GW, Levi R. Cardioprotective effect of histamine H3-receptor activation: pivotal role of G beta gamma-dependent inhibition of voltage-operated Ca2+ channels. J Pharmacol Exp Ther 2008; 326:871-8. [PMID: 18523159 DOI: 10.1124/jpet.108.137919] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously showed that activation of G(i/o)-coupled histamine H(3)-receptors (H(3)R) is cardioprotective because it attenuates excessive norepinephrine release from cardiac sympathetic nerves. This action is characterized by a marked decrease in intraneuronal Ca(2+) ([Ca(2+)](i)), as G alpha(i) impairs the adenylyl cyclase-cAMP-protein kinase A (PKA) pathway, and this decreases Ca(2+) influx via voltage-operated Ca(2+) channels (VOCC). Yet, the G(i/o)-derived betagamma dimer could directly inhibit VOCC, and the subsequent reduction in Ca(2+) influx would be responsible for the H(3)R-mediated attenuation of transmitter exocytosis. In this study, we tested this hypothesis in nerve-growth factor-differentiated rat pheochromocytoma cells (PC12) stably transfected with H(3)R (PC12-H(3)) and with the G betagamma scavenger beta-adrenergic receptor kinase 1 (beta-ARK1)-(495-689)-polypeptide (PC12-H(3)/beta-ARK1). Thus, we evaluated the effects of H(3)R activation directly on the following: 1) Ca(2+) current (I(Ca)) using the whole-cell patch-clamp technique; and 2) K(+)-induced exocytosis of endogenous dopamine. H(3)R activation attenuated both peak I(Ca) and dopamine exocytosis in PC12-H(3) but not in PC12-H(3)/beta-ARK1 cells. Moreover, a membrane permeable phosducin-like G betagamma scavenger also prevented the antiexocytotic effect of H(3)R activation. In contrast, the H(3)R-induced attenuation of cAMP accumulation and dopamine exocytosis in response to forskolin were the same in both PC12-H(3) and PC12-H(3)/beta-ARK1 cells. Our findings reveal that although G alpha(i) participates in the H(3)-mediated antiexocytotic effect when the adenylyl cyclase-cAMP-PKA pathway is stimulated, a direct G betagamma-induced inhibition of VOCC, resulting in an attenuation of I(Ca), plays a pivotal role in the H(3)R-mediated decrease in [Ca(2+)](i) and associated cardioprotective antiexocytotic effects. The discovery of this H(3)R-signaling step may offer new therapeutic approaches to cardiovascular diseases characterized by hyperadrenergic activity.
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Affiliation(s)
- Christopher Morrey
- Department of Pharmacology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065-4896, USA
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