A functional study of all 40

Area of Science:

• * Developmental Biology
• * Endocrinology
• * Genetics

Background:

• * The Caenorhabditis elegans genome encodes 40 insulin-like genes (INS), significantly more than the 10 found in humans.
• * Functional redundancy among these numerous INS peptides makes determining their individual roles challenging using traditional knockout methods.

Purpose of the Study:

• * To comprehensively characterize the in vivo functions of all 40 C. elegans INS peptides.
• * To categorize each INS peptide as an agonist, antagonist, or having pleiotropic effects.
• * To correlate INS peptide structure with their biological functions.

Main Methods:

• * Pan-neuronal overexpression of each of the 40 ins genes in C. elegans.
• * Monitoring of key phenotypes: L1 arrest lifespan, neuroblast divisions during L1 arrest, dauer formation, and fat accumulation.

Main Results:

• * Functional roles were identified for 35 out of 40 INS peptides.
• * A subset of 9 agonistic INS peptides were found to shorten L1 arrest lifespan and promote neuroblast divisions.
• * A specific structural feature, the F peptide sequence within β-class INS peptides, was identified as characteristic of agonists.

Conclusions:

• * This study provides the first comprehensive functional categorization of all 40 C. elegans INS peptides.
• * The findings establish a structure-function relationship for INS peptides in vivo.
• * This research lays the groundwork for understanding insulin signaling in development, metabolism, and aging-related diseases.