# CPD-1 can compensate for EGL-21 to process neuropeptides

## TL;DR

This study shows that CPD-1 can help process neuropeptides when another enzyme, EGL-21, is missing, affecting defecation in C. elegans.

## Contribution

The novel finding is that CPD-1 compensates for EGL-21 in neuropeptide processing, specifically in C. elegans defecation.

## Key findings

- cpd-1 mutants alone do not cause defecation defects.
- cpd-1 enhances defecation defects in egl-21 mutants.
- CPD-1 acts in intestinal cells and possibly GABAergic neurons.

## Abstract

Carboxypeptidase D has been thought to process neuropeptides, though its role has not been fully characterized. Since specific neuropeptides regulate the defecation motor program of

C. elegans

, we used genetic analysis to determine how loss of the worm carboxypeptidase D ortholog
CPD-1
affects defecation. We found that

cpd-1

mutants do not have defecation defects but enhance the defecation defects of

egl-21

mutants lacking carboxypeptidase E, a major neuropeptide processing enzyme. We also found that
CPD-1
acts in intestinal cells and possibly GABAergic neurons to promote defecation. These results suggest that
CPD-1
can process neuropeptides, specifically in the absence of
EGL-21
.