Cargando…

Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells

Zinc has an important role in normal pancreatic beta cell physiology as it regulates gene transcription, insulin crystallization and secretion, and cell survival. Nevertheless, little is known about how zinc is transported through the plasma membrane of beta cells and which of the class of zinc infl...

Descripción completa

Detalles Bibliográficos
Autores principales: Hardy, Alexandre B., Prentice, Kacey J., Froese, Sean, Liu, Ying, Andrews, Glen K., Wheeler, Michael B.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4373830/
https://www.ncbi.nlm.nih.gov/pubmed/25806541
http://dx.doi.org/10.1371/journal.pone.0119136
_version_ 1782363391624478720
author Hardy, Alexandre B.
Prentice, Kacey J.
Froese, Sean
Liu, Ying
Andrews, Glen K.
Wheeler, Michael B.
author_facet Hardy, Alexandre B.
Prentice, Kacey J.
Froese, Sean
Liu, Ying
Andrews, Glen K.
Wheeler, Michael B.
author_sort Hardy, Alexandre B.
collection PubMed
description Zinc has an important role in normal pancreatic beta cell physiology as it regulates gene transcription, insulin crystallization and secretion, and cell survival. Nevertheless, little is known about how zinc is transported through the plasma membrane of beta cells and which of the class of zinc influx transporters (Zip) is involved. Zip4 was previously shown to be expressed in human and mouse beta cells; however, its function there is still unknown. Therefore, the aim of this study was to define the zinc transport role of Zip4 in beta cells. To investigate this, Zip4 was over-expressed in MIN6 beta cells using a pCMV6-Zip4GFP plasmid. Organelle staining combined with confocal microscopy showed that Zip4 exhibits a widespread localization in MIN6 cells. Time-lapse zinc imaging experiments showed that Zip4 increases cytoplasmic zinc levels. This resulted in increased granular zinc content and glucose-stimulated insulin secretion. Interestingly, it is unlikely that the increased glucose stimulated insulin secretion was triggered by a modulation of mitochondrial function, as mitochondrial membrane potential remained unchanged. To define the role of Zip4 in-vivo, we generated a beta cell-specific knockout mouse model (Zip4BKO). Deletion of the Zip4 gene was confirmed in Zip4BKO islets by PCR, RT-PCR, and immuno-histochemistry. Zip4BKO mice showed slightly improved glucose homeostasis but no change in insulin secretion during an oral glucose tolerance test. While Zip4 was not found to be essential for proper glucose homeostasis and insulin secretion in vivo in mice, this study also found that Zip4 mediates increases in cytoplasmic and granular zinc pools and stimulates glucose dependant insulin secretion in-vitro.
format Online
Article
Text
id pubmed-4373830
institution National Center for Biotechnology Information
language English
publishDate 2015
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-43738302015-03-27 Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells Hardy, Alexandre B. Prentice, Kacey J. Froese, Sean Liu, Ying Andrews, Glen K. Wheeler, Michael B. PLoS One Research Article Zinc has an important role in normal pancreatic beta cell physiology as it regulates gene transcription, insulin crystallization and secretion, and cell survival. Nevertheless, little is known about how zinc is transported through the plasma membrane of beta cells and which of the class of zinc influx transporters (Zip) is involved. Zip4 was previously shown to be expressed in human and mouse beta cells; however, its function there is still unknown. Therefore, the aim of this study was to define the zinc transport role of Zip4 in beta cells. To investigate this, Zip4 was over-expressed in MIN6 beta cells using a pCMV6-Zip4GFP plasmid. Organelle staining combined with confocal microscopy showed that Zip4 exhibits a widespread localization in MIN6 cells. Time-lapse zinc imaging experiments showed that Zip4 increases cytoplasmic zinc levels. This resulted in increased granular zinc content and glucose-stimulated insulin secretion. Interestingly, it is unlikely that the increased glucose stimulated insulin secretion was triggered by a modulation of mitochondrial function, as mitochondrial membrane potential remained unchanged. To define the role of Zip4 in-vivo, we generated a beta cell-specific knockout mouse model (Zip4BKO). Deletion of the Zip4 gene was confirmed in Zip4BKO islets by PCR, RT-PCR, and immuno-histochemistry. Zip4BKO mice showed slightly improved glucose homeostasis but no change in insulin secretion during an oral glucose tolerance test. While Zip4 was not found to be essential for proper glucose homeostasis and insulin secretion in vivo in mice, this study also found that Zip4 mediates increases in cytoplasmic and granular zinc pools and stimulates glucose dependant insulin secretion in-vitro. Public Library of Science 2015-03-25 /pmc/articles/PMC4373830/ /pubmed/25806541 http://dx.doi.org/10.1371/journal.pone.0119136 Text en © 2015 Hardy et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Hardy, Alexandre B.
Prentice, Kacey J.
Froese, Sean
Liu, Ying
Andrews, Glen K.
Wheeler, Michael B.
Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells
title Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells
title_full Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells
title_fullStr Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells
title_full_unstemmed Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells
title_short Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells
title_sort zip4 mediated zinc influx stimulates insulin secretion in pancreatic beta cells
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4373830/
https://www.ncbi.nlm.nih.gov/pubmed/25806541
http://dx.doi.org/10.1371/journal.pone.0119136
work_keys_str_mv AT hardyalexandreb zip4mediatedzincinfluxstimulatesinsulinsecretioninpancreaticbetacells
AT prenticekaceyj zip4mediatedzincinfluxstimulatesinsulinsecretioninpancreaticbetacells
AT froesesean zip4mediatedzincinfluxstimulatesinsulinsecretioninpancreaticbetacells
AT liuying zip4mediatedzincinfluxstimulatesinsulinsecretioninpancreaticbetacells
AT andrewsglenk zip4mediatedzincinfluxstimulatesinsulinsecretioninpancreaticbetacells
AT wheelermichaelb zip4mediatedzincinfluxstimulatesinsulinsecretioninpancreaticbetacells