Piantadosi C A, Dickerman H W, Spivak J L
J Clin Invest. 1976 Jan;57(1):20-6. doi: 10.1172/JCI108260.
The spleen of the ex-hypoxic polycythemic mouse was employed to study the effect of erythropoietin on nuclear RNA polymerase activity. On the basis of ionic strength requirements and sensitivity to the fungal toxin alpha-amanitin, two major forms (I and II) of nuclear RNA polymerase were identified. Within 0.5 h after administration of erythropoietin, at a time when no morphologically identifiable erythroblasts were present in the spleen, there was an increase in the activity of polymerase II. By 2 h, polymerase II activity had declined to control levels. At 3 h, polymerase I activity began to increase, rising to a peak, 88% above control levels, by 12 h. During this period, early erythroblasts began to appear in the spleen. At 12 h, a second increase of similar magnitude occurred in polymerase II activity. Polymerase I activity fell to control levels by 18 h while polymerase II declined more slowly. These data indicate that stimulation of transcription is an early effect of erythropoietin. Multiple forms of RNA polymerase are involved and activation of these is sequential. Nuclear RNA polymerase activity is maximal during the period of early erythroblast proliferation and declines as these cells mature.
利用低氧后红细胞增多症小鼠的脾脏来研究促红细胞生成素对核RNA聚合酶活性的影响。根据离子强度要求和对真菌毒素α-鹅膏蕈碱的敏感性，确定了核RNA聚合酶的两种主要形式（I和II）。在注射促红细胞生成素后0.5小时内，此时脾脏中尚无形态上可识别的成红细胞，聚合酶II的活性就有所增加。到2小时时，聚合酶II的活性已降至对照水平。3小时时，聚合酶I的活性开始增加，到12小时时升至峰值，比对照水平高88%。在此期间，早期成红细胞开始出现在脾脏中。12小时时，聚合酶II的活性出现了类似幅度的第二次增加。聚合酶I的活性在18小时时降至对照水平，而聚合酶II下降得更慢。这些数据表明转录的刺激是促红细胞生成素的早期作用。涉及多种形式的RNA聚合酶，且这些酶的激活是顺序性的。核RNA聚合酶活性在早期成红细胞增殖期间最高，并随着这些细胞的成熟而下降。
