Human Y-79 Retinoblastoma Cells Exhibit Specific Insulin Receptors.
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD
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The presence of insulin receptors was investigated in human Y-79 retinoblastoma cells grown in suspension culture. The binding of 125I insulin to these cells was time-, temperature-, and pH-dependent, was competed fo by insulin and proinsulin but not other peptides, and was inhibited by antibodies against the insulin receptor. The Scatchard plot of insulin competition data was curvilinear and was resolved in a high affinity K subscript d approx. o.5x10 to the -10th power M - low capacity approx 3,000 sitescell and a low affinity K subscript d approx. .0000001 M - high capacity approx. 155,000 sitescell component. Negative cooperativity was not found, in agreement with other studies in rodent neural cells. However, in contrast to studies with rodent cells, insulin specifically down-regulated its receptor on human Y-79 cells after prolonged exposure. In conclusion, these data show for the first time the presence of specific insulin receptors in human Y-79 retinoblastoma cells. As these cells were previously shown to have several characteristics typical of neural cells, we propose their use as a model to study the effects of insulin on neural and retinal tissues of human origin. Author