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Updated: Mar 16, 2026
Quantifying Tissue-Specific Proteostatic Decline in Caenorhabditis elegans
Published on: September 7, 2021
Global Cysteine-Reactivity Profiling during Impaired Insulin/IGF-1 Signaling in C. elegans Identifies Uncharacterized
Julianne Martell1, Yonghak Seo2, Daniel W Bak1
1Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA.
Abstract:
In the nematode Caenorhabditis elegans, inactivating mutations in the insulin/IGF-1 receptor, DAF-2, result in a 2-fold increase in lifespan mediated by DAF-16, a FOXO-family transcription factor. Downstream protein activities that directly regulate longevity during impaired insulin/IGF-1 signaling (IIS) are poorly characterized. Here, we use global cysteine-reactivity profiling to identify protein activity changes during impaired IIS. Upon confirming that cysteine reactivity is a good predictor of functionality in C. elegans, we profiled cysteine-reactivity changes between daf-2 and daf-16;daf-2 mutants, and identified 40 proteins that display a >2-fold change. Subsequent RNAi-mediated knockdown studies revealed that lbp-3 and K02D7.1 knockdown caused significant increases in lifespan and dauer formation. The proteins encoded by these two genes, LBP-3 and K02D7.1, are implicated in intracellular fatty acid transport and purine metabolism, respectively. These studies demonstrate that cysteine-reactivity profiling can be complementary to abundance-based transcriptomic and proteomic studies, serving to identify uncharacterized mediators of C. elegans longevity.
Insights
Identifying new longevity mediators in C. elegans, this study reveals that altered protein activity, not just abundance, is key. Cysteine-reactivity profiling pinpointed LBP-3 and K02D7.1 as crucial for lifespan regulation.
Area of Science:
- Molecular Biology
- Aging Research
- Proteomics
Background:
- Mutations in the insulin/IGF-1 receptor (DAF-2) in C. elegans extend lifespan via DAF-16.
- The specific protein activities regulating longevity under impaired insulin/IGF-1 signaling (IIS) remain largely unknown.
Purpose of the Study:
- To identify protein activity changes associated with impaired IIS using global cysteine-reactivity profiling.
- To uncover novel genes and pathways that modulate longevity in C. elegans.
Main Methods:
- Global cysteine-reactivity profiling was employed to assess protein activity changes in daf-2 and daf-16;daf-2 mutants.
- RNAi-mediated knockdown was used to validate the role of identified proteins in lifespan and dauer formation.
Main Results:
- Cysteine reactivity was confirmed as a reliable indicator of protein functionality in C. elegans.
- Forty proteins showed >2-fold changes in cysteine reactivity between mutant strains.
- Knockdown of lbp-3 and K02D7.1 significantly increased lifespan and dauer formation.
Conclusions:
- Cysteine-reactivity profiling is a valuable tool for identifying uncharacterized longevity mediators.
- LBP-3 (intracellular fatty acid transport) and K02D7.1 (purine metabolism) are novel regulators of C. elegans longevity.
- This approach complements traditional transcriptomic and proteomic studies by focusing on protein activity.
