p53- and p73-independent activation of TIGAR expression in vivo
TIGAR (TP53-induced glycolysis and apoptosis regulator) functions as a fructose-2,6-bisphosphatase and its expression results in a dampening of the glycolytic pathway, while increasing antioxidant capacity by increasing NADPH and GSH levels. In addition to being a p53 target, p53-independent expression of TIGAR is also seen in many human cancer cell lines that lack wild-type p53. Although human TIGAR expression can be induced by p53, TAp63 and TAp73, mouse TIGAR is less responsive to the p53 family members and basal levels of TIGAR expression does not depend on p53 or TAp73 expression in most mouse tissues in vivo. Although mouse TIGAR expression is clearly induced in the intestines of mice following DNA-damaging stress such as ionising radiation, this is also not dependent on p53 or TAp73.