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Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo

Human proinsulin with C-peptide–bearing Superfolder Green Fluorescent Protein (CpepSfGFP) has been expressed in transgenic mice, driven by the Ins1 promoter. The protein, expressed exclusively in β-cells, is processed and stored as CpepSfGFP and human insulin comprising only ∼0.04% of total islet pr...

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Autores principales: Zhu, Shuaishuai, Larkin, Dennis, Lu, Shusheng, Inouye, Candice, Haataja, Leena, Anjum, Arfah, Kennedy, Robert, Castle, David, Arvan, Peter
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Diabetes Association 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4764152/
https://www.ncbi.nlm.nih.gov/pubmed/26647386
http://dx.doi.org/10.2337/db15-1264
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author Zhu, Shuaishuai
Larkin, Dennis
Lu, Shusheng
Inouye, Candice
Haataja, Leena
Anjum, Arfah
Kennedy, Robert
Castle, David
Arvan, Peter
author_facet Zhu, Shuaishuai
Larkin, Dennis
Lu, Shusheng
Inouye, Candice
Haataja, Leena
Anjum, Arfah
Kennedy, Robert
Castle, David
Arvan, Peter
author_sort Zhu, Shuaishuai
collection PubMed
description Human proinsulin with C-peptide–bearing Superfolder Green Fluorescent Protein (CpepSfGFP) has been expressed in transgenic mice, driven by the Ins1 promoter. The protein, expressed exclusively in β-cells, is processed and stored as CpepSfGFP and human insulin comprising only ∼0.04% of total islet proinsulin plus insulin, exerting no metabolic impact. The kinetics of the release of insulin and CpepSfGFP from isolated islets appear identical. Upon a single acute stimulatory challenge in vitro, fractional release of insulin does not detectably deplete islet fluorescence. In vivo, fluorescence imaging of the pancreatic surface allows, for the first time, visual assessment of pancreatic islet insulin content, and we demonstrate that CpepSfGFP visibly declines upon diabetes progression in live lepR(db)(/)(db) mice. In anesthetized mice, after intragastric or intravenous saline delivery, pancreatic CpepSfGFP (insulin) content remains undiminished. Remarkably, however, within 20 min after acute intragastric or intravenous glucose delivery (with blood glucose concentrations reaching >15 mmol/L), a small subset of islets shows rapid dispossession of a major fraction of their stored CpepSfGFP (insulin) content, whereas most islets exhibit no demonstrable loss of CpepSfGFP (insulin). These studies strongly suggest that there are “first responder” islets to an in vivo glycemic challenge, which cannot be replicated by islets in vitro.
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spelling pubmed-47641522017-03-01 Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo Zhu, Shuaishuai Larkin, Dennis Lu, Shusheng Inouye, Candice Haataja, Leena Anjum, Arfah Kennedy, Robert Castle, David Arvan, Peter Diabetes Islet Studies Human proinsulin with C-peptide–bearing Superfolder Green Fluorescent Protein (CpepSfGFP) has been expressed in transgenic mice, driven by the Ins1 promoter. The protein, expressed exclusively in β-cells, is processed and stored as CpepSfGFP and human insulin comprising only ∼0.04% of total islet proinsulin plus insulin, exerting no metabolic impact. The kinetics of the release of insulin and CpepSfGFP from isolated islets appear identical. Upon a single acute stimulatory challenge in vitro, fractional release of insulin does not detectably deplete islet fluorescence. In vivo, fluorescence imaging of the pancreatic surface allows, for the first time, visual assessment of pancreatic islet insulin content, and we demonstrate that CpepSfGFP visibly declines upon diabetes progression in live lepR(db)(/)(db) mice. In anesthetized mice, after intragastric or intravenous saline delivery, pancreatic CpepSfGFP (insulin) content remains undiminished. Remarkably, however, within 20 min after acute intragastric or intravenous glucose delivery (with blood glucose concentrations reaching >15 mmol/L), a small subset of islets shows rapid dispossession of a major fraction of their stored CpepSfGFP (insulin) content, whereas most islets exhibit no demonstrable loss of CpepSfGFP (insulin). These studies strongly suggest that there are “first responder” islets to an in vivo glycemic challenge, which cannot be replicated by islets in vitro. American Diabetes Association 2016-03 2015-12-08 /pmc/articles/PMC4764152/ /pubmed/26647386 http://dx.doi.org/10.2337/db15-1264 Text en © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.
spellingShingle Islet Studies
Zhu, Shuaishuai
Larkin, Dennis
Lu, Shusheng
Inouye, Candice
Haataja, Leena
Anjum, Arfah
Kennedy, Robert
Castle, David
Arvan, Peter
Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo
title Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo
title_full Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo
title_fullStr Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo
title_full_unstemmed Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo
title_short Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo
title_sort monitoring c-peptide storage and secretion in islet β-cells in vitro and in vivo
topic Islet Studies
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4764152/
https://www.ncbi.nlm.nih.gov/pubmed/26647386
http://dx.doi.org/10.2337/db15-1264
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