ATM-dependent activation of the IGF-IR promoter. To examine activation
of the IGF-IR promoter as a function of ATM status, the indicated cells
were transfected with a plasmid containing the luciferase gene driven
by base pairs −2350 to +640 of the rat IGF-IR promoter region, along
with a β-galactosidase expression vector as a control for
transfection efficiency. The luciferase activity, as a measure of
IGF-IR activation, was normalized to β-gal expression in each case.
Experiments were performed in triplicate, and the results shown are the
mean of three separate experiments. (A) Comparison of
IGF-IR promoter activity in ATM-deficient GM5849 cells
(SV40-transformed fibroblasts) and a subclone transfected with a vector
expressing wild-type ATM cDNA (5849cA2), along with an unrelated
wild-type SV40 transformed fibroblast cell line, GM637.
(B) Comparison of IGF-IR promoter activity in primary AT
fibroblasts obtained from an affected individual (GM3487) and from his
heterozygous parent (GM3489).