INSULIN-RECEPTOR GENE-EXPRESSION IS REDUCED IN CELLS FROM A PROGERIC PATIENT

We have studied a 15-year-old girl (Pl) suffering from the Hutchinson-Gilford syndrome (progeria) associated with a severe insulin resistance. Insulin binding activity to Pl erythrocytes was 85% reduced when compared to that measured in ten normal controls matched for sex and age. This finding was confirmed in Epstein-Barr virus (EBV)-transformed lymphoblasts and depends on a reduction in insulin receptor number. Also the amount of total insulin receptors, [S-35]methionine labeled and immunoprecipitated, was 90% reduced in Pl lymphoblasts when compared to controls. Next, we measured insulin receptor mRNA levels and we found undetectable levels of insulin receptor transcript in Pl EBV-transformed lymphoblasts, in the absence of any rearrangement of insulin receptor gene as evaluated by Southern blot analysis. The marked reduction in insulin receptor gene expression probably accounts for the severe insulin resistance presented by the patient. Despite extensive studies, the molecular basis of progeria is still unknown. The near complete absence of a molecule crucial in the transduction of cell growth and differentiation signals could be involved in the accelerated aging of the patient.