drr‐2 encodes an eIF4H that acts downstream of TOR in diet‐restriction‐induced longevity of C. elegans

Dietary restriction (DR) results in a robust increase in lifespan while maintaining the physiology of much younger animals in a wide range of species. Here, we examine the role of drr‐2, a DR‐responsive gene recently identified, in determining the longevity of Caenorhabditis elegans. Inhibition of drr‐2 has been shown to increase longevity. However, the molecular mechanisms by which drr‐2 influences longevity remain unknown. We report here that drr‐2 encodes an ortholog of human eukaryotic translation initiation factor 4H (eIF4H), whose function is to mediate the initiation step of mRNA translation. The molecular function of DRR‐2 is validated by the association of DRR‐2 with polysomes and by the decreased rate of protein synthesis observed in drr‐2 knockdown animals. Previous studies have also suggested that DR might trigger a regulated reduction in drr‐2 expression to initiate its longevity response. By examining the effect of increasing drr‐2 expression on DR animals, we find that drr‐2 is essential for a large portion of the longevity response to DR. The nutrient‐sensing target of rapamycin (TOR) pathway has been shown to mediate the longevity effects of DR in C. elegans. Results from our genetic analyses suggest that eIF4H/DRR‐2 functions downstream of TOR, but in parallel to the S6K/PHA‐4 pathway to mediate the lifespan effects of DR. Together, our findings reveal an important role for eIF4H/drr‐2 in the TOR‐mediated longevity responses to DR.