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AQP8 is a crucial H2O2 transporter in insulin-producing RINm5F cells
Christina Krüger1, Markus Waldeck-Weiermair2, Jonas Kaynert1
1Institute of Clinical Biochemistry, Hannover Medical School, 30623, Hannover, Germany.
Redox Biology
|April 23, 2021
Summary
Aquaporin-8 (AQP8) facilitates hydrogen peroxide (H2O2) transport in pancreatic cells, impacting insulin secretion and diabetes mellitus. AQP8 overexpression increases proliferation and insulin content, highlighting its role in H2O2 homeostasis.
Area of Science:
- Cell Biology
- Biochemistry
- Physiology
Background:
- Peroxiporins, a subset of aquaporins (AQPs), transport hydrogen peroxide (H2O2) across cell membranes.
- H2O2 is crucial for cell signaling but excessive amounts impair insulin secretion, linking it to diabetes mellitus (DM) pathogenesis.
- Aquaporin-8 (AQP8) is investigated for its role as a peroxiporin in pancreatic beta-cells.
Purpose of the Study:
- To investigate the function of AQP8 as a peroxiporin in RINm5F insulin-producing cells.
- To elucidate the role of AQP8 in regulating H2O2 homeostasis and its impact on pancreatic beta-cell function.
- To determine the subcellular localization and H2O2 transport activity of AQP8.
Main Methods:
- Stable AQP8 overexpression (AQP8↑) and CRISPR/Cas9-mediated AQP8 knockdown (KD) in RINm5F cells.
- Tet-On-regulated lentiviral re-expression of AQP8 to enable functional characterization after knock-out.
- Confocal microscopy for V5-tagged AQP8 localization and live-cell imaging using HyPer and HyPer7.2 biosensors for H2O2 flux analysis.
Main Results:
- Complete AQP8 knock-out led to cell death; mild re-expression allowed survival and functional studies.
- AQP8 overexpression (AQP8↑) increased cell proliferation and insulin content, indicating a role in H2O2 homeostasis.
- AQP8 localized to the mitochondria and plasma membrane, facilitating H2O2 transport to these sites, confirmed by HyPer7.2 biosensor.
Conclusions:
- AQP8 functions as a significant H2O2 transporter in pancreatic beta-cells (RINm5F).
- AQP8 plays a critical role in regulating H2O2 flux through the mitochondria and plasma membrane.
- These findings contribute to understanding H2O2 transport and toxicity in pancreatic beta-cells and may inform type-1 DM research.
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