Stimulation of labeling of rat-liver nuclear ribonucleic acid by insulin.

Abstract

The action of insulin on the labeling of nuclear RNA of liver of diabetic rats has been examined using columns of kieselguhr coated with methylated albumin. The nuclear RNA was fractionated into a ribosomal fraction (Q1 RNA) and two DNA-like RNA fractions (Q2 and TD RNA). Diabetes diminished the labeling of TD RNA (major DNA-like RNA fraction) by 25% after a 20-min pulse with [3H]orotic acid, but the labeling of the other two RNA fractions remained unchanged. A one-hour period of insulin treatment stimulated the labeling of Q2 RNA and TD RNA by about 50% but had little effect on Q1 RNA. Between 2 and 4.5 h after insulin, the labeling of Q1 RNA increased along with that of TD RNA, but no increase in Q2 RNA labeling occurred. Six hours after treatment with insulin, the rate of labeling of all three RNA fractions approached the untreated diabetic level. It is concluded that insulin stimulates the synthesis of ribosomal and DNA-like RNA in rat liver.