Genetic analysis of hyl-1, the C. elegans homolog of LAG1/LASS1.

Yeast LAG1 was one of the first longevity genes found. Subsequent analysis showed that it encodes a component of ceramide synthase. Homologs of LAG1 have been identified in all eukaryotes examined for their presence, and multiple homologs are the norm. In human and mouse, the LAG1 counterpart is called LASS1. The involvement of this gene in determining yeast replicative life span led us to ask whether longevity effects could be found in C. elegans. Extended longevity was seen when we used RNAi to decrease expression of the worm homolog of LAG1, termed hyl-1, for Homolog of Yeast Longevity gene. In contrast, neither deletion of the gene nor overexpression resulted in life extension. There was no evidence that hyl-1 interacts with the insulin/IGF-1 like signaling pathway to specify longevity or dauer formation, nor were effects on stress resistance detected. Gene expression of hyl-1 homologs was altered in the deletion mutant and by RNAi, showing distinct evidence for compensation at the transcript level. These regulatory changes may explain the subtle phenotypic effects found under the conditions studied here.