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Tudurí E, Glavas MM, Asadi A, Baker RK, Ellis CE, Soukhatcheva G, Philit M, Huynh FK, Johnson JD, Bruce Verchere C, Kieffer TJ. AAV GCG-EGFP, a new tool to identify glucagon-secreting α-cells. Sci Rep 2019; 9:10829. [PMID: 31346189 PMCID: PMC6658537 DOI: 10.1038/s41598-019-46735-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/04/2019] [Indexed: 01/07/2023] Open
Abstract
The study of primary glucagon-secreting α-cells is hampered by their low abundance and scattered distribution in rodent pancreatic islets. We have designed a double-stranded adeno-associated virus containing a rat proglucagon promoter (700 bp) driving enhanced green fluorescent protein (AAV GCG-EGFP), to specifically identify α-cells. The administration of AAV GCG-EGFP by intraperitoneal or intraductal injection led to EGFP expression selectively in the α-cell population. AAV GCG-EGFP delivery to mice followed by islet isolation, dispersion and separation by FACS for EGFP resulted in an 86% pure population of α-cells. Furthermore, the administration of AAV GCG-EGFP at various doses to adult wild type mice did not significantly alter body weight, blood glucose, plasma insulin or glucagon levels, glucose tolerance or arginine tolerance. In vitro experiments in transgene positive α-cells demonstrated that EGFP expression did not alter the intracellular Ca2+ pattern in response to glucose or adrenaline. This approach may be useful for studying purified primary α-cells and for the in vivo delivery of other genes selectively to α-cells to further probe their function or to manipulate them for therapeutic purposes.
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain.,Instituto de Investigación, Desarrollo e innovación en Biotecnología Sanitaria de Elche (IDiBE), Elche, Spain
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ali Asadi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert K Baker
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Cara E Ellis
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Galina Soukhatcheva
- Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Marjolaine Philit
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Biological Sciences, San Jose State University, San Jose, CA, USA
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - C Bruce Verchere
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada. .,Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.
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Bround MJ, Asghari P, Wambolt RB, Bohunek L, Smits C, Philit M, Kieffer TJ, Lakatta EG, Boheler KR, Moore EDW, Allard MF, Johnson JD. Cardiac ryanodine receptors control heart rate and rhythmicity in adult mice. Cardiovasc Res 2012; 96:372-80. [PMID: 22869620 DOI: 10.1093/cvr/cvs260] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AIMS The molecular mechanisms controlling heart function and rhythmicity are incompletely understood. While it is widely accepted that the type 2 ryanodine receptor (Ryr2) is the major Ca(2+) release channel in excitation-contraction coupling, the role of these channels in setting a consistent beating rate remains controversial. Gain-of-function RYR2 mutations in humans and genetically engineered mouse models are known to cause Ca(2+) leak, arrhythmias, and sudden cardiac death. Embryonic stem-cell derived cardiomyocytes lacking Ryr2 display slower beating rates, but no supporting in vivo evidence has been presented. The aim of the present study was to test the hypothesis that RYR2 loss-of-function would reduce heart rate and rhythmicity in vivo. METHODS AND RESULTS We generated inducible, tissue-specific Ryr2 knockout mice with acute ∼50% loss of RYR2 protein in the heart but not in other tissues. Echocardiography, working heart perfusion, and in vivo ECG telemetry demonstrated that deletion of Ryr2 was sufficient to cause bradycardia and arrhythmia. Our results also show that cardiac Ryr2 knockout mice exhibit functional and structural hallmarks of heart failure, including sudden cardiac death. CONCLUSION These results illustrate that the RYR2 channel plays an essential role in pacing heart rate. Moreover, we find that RYR2 loss-of-function can lead to fatal arrhythmias typically associated with gain-of-function mutations. Given that RYR2 levels can be reduced in pathological conditions, including heart failure and diabetic cardiomyopathy, we predict that RYR2 loss contributes to disease-associated bradycardia, arrhythmia, and sudden death.
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Affiliation(s)
- Michael J Bround
- Cardiovascular Research Group, Life Sciences Institute, University of British Columbia, 5358 Life Sciences Building, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
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Latta M, Philit M, Maury I, Soubrier F, Denèfle P, Mayaux JF. Tryptophan promoter derivatives on multicopy plasmids: a comparative analysis of expression potentials in Escherichia coli. DNA Cell Biol 1990; 9:129-37. [PMID: 2188657 DOI: 10.1089/dna.1990.9.129] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A collection of variant plasmids expressing either Escherichia coli galactokinase or human serum albumin under the control of several E. coli trp promoter derivatives were constructed and studied for both efficiency of expression and regulation by tryptophan. Several variables, including the length of the upstream region, tandem duplications of a core promoter, and the insertion of the trp repressor trpR gene onto the expression vector, were studied. It is shown that derivatives containing sequences upstream from the -35 region or multiple copies of the trp promoter produce twofold higher levels of protein than plasmids with a minimal trp promoter truncated at -40. We show that the expression of a heterologous protein such as albumin can be significantly improved (13% vs. 7% of total proteins) if both the upstream trp promoter region, which enhances promoter strength, and an intact trpR gene, are included on the plasmids.
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Affiliation(s)
- M Latta
- Laboratoire de Génétique, Institut de Biotechnologie, Rhône-Poulenc Santé, France
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