Zerwekh J E, Haussler M R, Lindell T J
Proc Natl Acad Sci U S A. 1974 Jun;71(6):2337-41. doi: 10.1073/pnas.71.6.2337.
1alpha,25-dihydroxyvitamin D(3) was examined for its ability to affect the DNA-dependent RNA polymerases (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) of rachitic chick intestinal cell nuclei in vivo. Nucleoplasmic (form II) RNA polymerase activity was stimulated 2-fold (P < 0.05) within 2-3 hr after an oral dose of 0.27 mug (0.65 nmol) of 1alpha,25-dihydroxyvitamin D(3) to rachitic chicks. The form II polymerase activity returned to control values by 5-9 hr after dosing with the sterol. In contrast, the nucleolar (form I) RNA polymerase was not increased within this period. Solubilization of nuclear protein and resolution of the two RNA polymerases on DEAE-Sephadex also revealed that there was an increase in polymerase II activity when assayed on exogenous DNA template. This evidence suggests that 1alpha,25-dihydroxyvitamin D(3) acts at the level of the enzymology of intestinal cell transcription and that increased mRNA synthesis after administration of this hormone cannot be due solely to a change in chromatin template activity.
研究了1α,25 - 二羟基维生素D(3)在体内影响佝偻病雏鸡肠细胞核中依赖DNA的RNA聚合酶(核苷三磷酸:RNA核苷酸转移酶,EC 2.7.7.6)的能力。给佝偻病雏鸡口服0.27微克(0.65纳摩尔)的1α,25 - 二羟基维生素D(3)后,在2 - 3小时内,核质(II型)RNA聚合酶活性被刺激增加了2倍(P < 0.05)。在用该固醇给药后5 - 9小时,II型聚合酶活性恢复到对照值。相比之下,在此期间核仁(I型)RNA聚合酶没有增加。对核蛋白进行溶解并在DEAE - 葡聚糖上分离这两种RNA聚合酶,结果还表明,在外源DNA模板上进行测定时,聚合酶II活性有所增加。这一证据表明,1α,25 - 二羟基维生素D(3)作用于肠细胞转录的酶学水平,并且给予这种激素后mRNA合成增加不能仅仅归因于染色质模板活性的变化。