The zinc transporter ZNT3 co-localizes with insulin in INS-1E pancreatic beta cells and influences cell survival, insulin secretion capacity, and ZNT8 expression

TY - JOUR

T1 - The zinc transporter ZNT3 co-localizes with insulin in INS-1E pancreatic beta cells and influences cell survival, insulin secretion capacity, and ZNT8 expression

AU - Smidt, Kamille

AU - Larsen, Agnete

AU - Brønden, Andreas

AU - Sørensen, Karen S

AU - Nielsen, Julie V

AU - Praetorius, Jeppe

AU - Martensen, Pia M.

AU - Rungby, Jørgen

PY - 2016/4

Y1 - 2016/4

N2 - Zinc trafficking in pancreatic beta cells is tightly regulated by zinc transporting (ZNTs) proteins. The role of different ZNTs in the beta cells is currently being clarified. ZNT8 transports zinc into insulin granules and is critical for a correct insulin crystallization and storage in the granules whereas ZNT3 knockout negatively affects beta cell function and survival. Here, we describe for the first time the sub-cellular localization of ZNT3 by immuno-gold electron microscopy and supplement previous data from knockout experiments with investigations of the effect of ZNT3 in a pancreatic beta cell line, INS-1E overexpressing ZNT3. In INS-1E cells, we found that ZNT3 was abundant in insulin containing granules located close to the plasma membrane. The level of ZNT8 mRNA was significantly decreased upon over-expression of ZNT3 at different glucose concentrations (5, 11 and 21 mM glucose). ZNT3 over-expression decreased insulin content and insulin secretion whereas ZNT3 over-expression improved the cell survival after 24 h at varying glucose concentrations (5, 11 and 21 mM). Our data suggest that ZNT3 and ZNT8 (known to regulate insulin secretion) have opposite effects on insulin synthesis and secretion possibly by a transcriptional co-regulation since mRNA expression of ZNT3 was inversely correlated to ZNT8 and ZNT3 over-expression reduced insulin synthesis and secretion in INS-1E cells. ZNT3 over-expression improved cell survival.

AB - Zinc trafficking in pancreatic beta cells is tightly regulated by zinc transporting (ZNTs) proteins. The role of different ZNTs in the beta cells is currently being clarified. ZNT8 transports zinc into insulin granules and is critical for a correct insulin crystallization and storage in the granules whereas ZNT3 knockout negatively affects beta cell function and survival. Here, we describe for the first time the sub-cellular localization of ZNT3 by immuno-gold electron microscopy and supplement previous data from knockout experiments with investigations of the effect of ZNT3 in a pancreatic beta cell line, INS-1E overexpressing ZNT3. In INS-1E cells, we found that ZNT3 was abundant in insulin containing granules located close to the plasma membrane. The level of ZNT8 mRNA was significantly decreased upon over-expression of ZNT3 at different glucose concentrations (5, 11 and 21 mM glucose). ZNT3 over-expression decreased insulin content and insulin secretion whereas ZNT3 over-expression improved the cell survival after 24 h at varying glucose concentrations (5, 11 and 21 mM). Our data suggest that ZNT3 and ZNT8 (known to regulate insulin secretion) have opposite effects on insulin synthesis and secretion possibly by a transcriptional co-regulation since mRNA expression of ZNT3 was inversely correlated to ZNT8 and ZNT3 over-expression reduced insulin synthesis and secretion in INS-1E cells. ZNT3 over-expression improved cell survival.

KW - Animals

KW - Cation Transport Proteins

KW - Cell Line

KW - Cell Survival

KW - Gene Expression

KW - Humans

KW - Insulin

KW - Insulin-Secreting Cells

KW - Protective Factors

KW - Protein Transport

KW - Rats

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1007/s10534-016-9915-7

DO - 10.1007/s10534-016-9915-7

M3 - Journal article

C2 - 26867900

SN - 0966-0844

VL - 29

SP - 287

EP - 298

JO - BioMetals

JF - BioMetals

IS - 2

ER -