Vitamin D3 Action on RNA Synthesis in Rat Intestinal Mucosa

Vitamin D3 action on uridine-5-3H incorporation into rat intestinal mucosal RNA was studied. The uridine was administered 1 hour after 2, 000 iu vitamin D3 treatment. Specific activity of RNA in nuclear and supernatant fractions was increased by vitamin D3 at 15 minutes after uridine-5-3H administration. Two hours after uridine-5-3H administration, specific activity of RNA in nuclei, mitochondria and supernatant were also increased, but it was decreased in microsome. Mucosal RNA was further analyzed by methylated albumin-kieselguhr column. It was found that uridine-5-3H incorporation into sRNA was increased and that into rRNA was decreased with vitamin D3 administration. DNA dependent RNA polymerase activities were studied in isolated nuclei obtained from rat intestinal mucosal cell. Mg2+-activated DNA dependent RNA polymerise was not influenced at 1 hour after vitamin D3 administration, however, decreased at 3 hours and 16 hours after vitamin D3 treatment. These decreases of activity would be corresponded with decreases of uridine-5-3H incorporation into rRNA. Mn2+ and (NH4)2SO4-activated DNA dependent RNA polymerase was not influenced by vitamin D3.