Diverse insulin-like peptides in Caenorhabditis elegans

Peptide hormones are conserved in living organisms to modulate homeostasis. To elucidate molecular mechanisms in the synthesis, secretion, and functions of peptide hormones, model organisms have been used. Caenorhabditis elegans, one of model organisms, is a good tool since: 1) genome size of the worm is small with over 40% homology to human genome, 2) numerous genetics methods are available, and 3) the worms are transparent throughout the life cycle, so that the secretion of peptide hormones can be followed at cellular level in living preparations by Green Fluorescent Protein tagged peptides. This review reports the structures, physiological functions, and secretion of insulin-like peptides, one family of peptide hormones, with our latest findings in the model organism, Caenorhabditis elegans.