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Mitochondrial function is required for secretion of DAF-28/insulin in C. elegans
Ola Billing1, Gautam Kao, Peter Naredi
1Department of Surgery and Perioperative Sciences, Umeå University, Umeå, Sweden.
Plos One
|January 26, 2011
Summary
Mitochondrial dysfunction, caused by TOMM-40 loss, impairs insulin secretion in C. elegans. This highlights mitochondrial role in regulating insulin signaling via DAF-28/insulin secretion.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Insulin signaling is crucial for development and aging in C. elegans.
- Factors regulating insulin ligand secretion remain largely unknown.
- Insulin receptor activation controls growth progression versus developmental arrest.
Purpose of the Study:
- Investigate the role of mitochondrial outer membrane translocase homologue TOMM-40 in insulin signaling.
- Determine the mechanism by which TOMM-40 influences insulin ligand secretion.
- Understand the link between mitochondrial function and insulin secretion.
Main Methods:
- RNA interference (RNAi) to reduce TOMM-40 levels.
- Assessment of larval growth arrest and insulin signaling strength.
- Mitochondrial protein import assays.
- Measurement of proton gradient across the inner mitochondrial membrane.
- Analysis of neuropeptide secretion (ANF::GFP, INS-22::VENUS).
Main Results:
- Reduced TOMM-40 levels cause larval growth arrest and decreased insulin signaling.
- TOMM-40 is essential for mitochondrial protein import.
- TOMM-40 inactivation triggers the mitochondrial unfolded protein response and collapses the mitochondrial proton gradient.
- Mitochondrial dysfunction prevents DAF-28/insulin secretion in response to food abundance.
- Secretion of other neuropeptides remains unaffected, indicating specificity.
Conclusions:
- Mitochondrial function, specifically TOMM-40 activity, is essential for DAF-28/insulin secretion in C. elegans.
- Mitochondrial dysfunction broadly impacts DAF-28 secretion.
- This pathway represents a novel regulatory mechanism for insulin signaling control.
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