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

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 <i>C. elegans</i> , we used genetic analysis to determine how loss of the worm carboxypeptidase D ortholog CPD-1 affects defecation. We found that <i>cpd-1</i> mutants do not have defecation defects but enhance the defecation defects of <i>egl-21</i> 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 .