FGT-1 is the Major Glucose Transporter in C. Elegans and is Central to Aging Pathways

Caenorhabditis elegans is widely used as a model for investigation of the relationships between aging, nutrient restriction and signalling via the DAF-2 (abnormal dauer formation 2) receptor for insulin-like peptides and AGE-1 [ageing alteration 1; orthologue of PI3K (phosphoinositide 3-kinase)], but the identity of the glucose transporters that may link these processes is unknown. We unexpectedly find that of the eight putative GLUT (glucose transporter)-like genes only the two splice variants of one gene have a glucose transport function in an oocyte expression system. We have named this gene fgt-1 (facilitated glucose transporter, isoform 1). We show that knockdown of fgt-1 RNA leads to loss of glucose transport and reduced glucose metabolism in wild-type worms. The FGT-1 glucose transporters of C. elegans thus play a key role in glucose energy supply to C. elegans. Importantly, knockdown of fgt-1 leads to an extension of lifespan equivalent, but not additive, to that observed in daf-2 and age-1 mutant worms. The results of the present study are consistent with DAF-2 and AGE-1 signalling stimulating glucose transport in C. elegans and this process being associated with the longevity phenotype in daf-2 and age-1 mutant worms. We propose that fgt-1 constitutes a common axis for the lifespan extending effects of nutrient restriction and reduced insulin-like peptide signalling.