Transketolase Haploinsufficiency Reduces Adipose Tissue and Female Fertility in Mice

Transketolase (TKT) is a ubiquitous enzyme used in multiple metabolic pathways. We show here by gene targeting that TKT-null mouse embryos are not viable and that disruption of one TKT allele can cause growth retardation (≈35%) and preferential reduction of adipose tissue (≈77%). Other TKT(+/−) tissues had moderate (≈33%; liver, gonads) or relatively little (≈7 to 18%; eye, kidney, heart, brain) reductions in mass. These mice expressed a normal level of growth hormone and reduced leptin levels. No phenotype was observed in the TKT(+/−) cornea, where TKT is especially abundant in wild-type mice. The small female TKT(+/−) mice mated infrequently and had few progeny (with a male/female ratio of 1.4:1) when pregnant. Thus, TKT in normal mice appears to be carefully balanced at a threshold level for well-being. Our data suggest that TKT deficiency may have clinical significance in humans and raise the possibility that obesity may be treated by partial inhibition of TKT in adipose tissue.