INSULIN MODULATION OF NEWLY SYNTHESIZED APOLIPOPROTEINS B-100 AND B-48 IN HUMAN FETAL INTESTINE - GENE-EXPRESSION AND MESSENGER-RNA EDITINGARE NOT INVOLVED

We investigated insulin's effect on intestinal lipid transport and, pa rticularly, the biogenesis of apolipoproteins crucial to lipoprotein s ecretion, Adding insulin (3 mU) to the serum-free medium of cultured j ejunal explants from human fetuses (17-20 weeks) reduced triglyceride and chylomicron production and inhibited apo B-48 and apo B-100 secret ion, When apo B mRNA was assayed by RT-PCR and its editing by primer e xtension, no change was detectable following the addition of insulin, HDL lipid content, apo A-1 synthesis and RNA level mere unaffected by insulin, Collectively, these results suggest that the insulin-stimulat ed decline in intestinal chylomicron output may involve apo B co- or p ost-translational modifications.