A Lineage-Specific Peptide Suppresses Juvenile Hormone to Drive Reproductive and Longevity Reprogramming in Ants

Area of Science:

• Social insect endocrinology
• Molecular basis of plasticity
• Evolutionary developmental biology

Background:

• Reproductive division of labor in eusocial insects is regulated by juvenile hormone (JH), which suppresses reproduction in workers.
• The precise mechanisms by which social cues lead to systemic JH suppression and reproductive activation remain largely unknown.
• The ant Harpegnathos saltator offers a model system where workers transition to reproductives (gamergates) after queen loss.

Purpose of the Study:

• To investigate the molecular mechanisms underlying socially induced reproductive plasticity in Harpegnathos saltator.
• To identify circulating factors involved in suppressing juvenile hormone (JH) signaling during worker transition to reproduction.

Main Methods:

• Proteomic analysis of ant hemolymph during the transition from worker to reproductive.
• Identification and characterization of interacting proteins, including HCRG1 and Hex70c.
• Functional studies using heterologous expression in Drosophila to assess HCRG1's effects on lifespan.

Main Results:

• A novel peptide, HCRG1, was identified and found to be upregulated during ritualistic dueling preceding reproductive transition.
• HCRG1 physically interacts with Hex70c, a juvenile hormone (JH)-binding protein, and antagonizes JH signaling to promote ovarian development.
• Expression of HCRG1 in Drosophila extended lifespan, suggesting conserved roles in longevity.

Conclusions:

• HCRG1 is an evolutionarily derived circulating factor that links social perception to systemic JH suppression.
• This mechanism enables coordinated transitions in reproduction and longevity in response to social cues in ants.
• The findings provide insights into the molecular underpinnings of social behavior and phenotypic plasticity.