Uridine incorporation and RNA synthesis during stimulation of lymphocytes by PHA.
Uridine incorporation and RNA synthesis during stimulation of lymphocytes by PHA.
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PHA 刺激淋巴细胞期间的尿苷掺入和 RNA 合成。
DOI：
10.1016/0014-4827(70)90230-2
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发表时间：
1970
影响因子：
3.7
通讯作者：
S. Handmaker
中科院分区：
文献类型：
--
作者：
J. Kay;S. Handmaker
PHA对淋巴细胞的转化伴随着~ 3 H-尿苷掺入RNA的速率显著增加。核苷似乎是嘧啶核苷酸在这个系统中的主要来源，但有证据表明，尿苷掺入RNA是有限的尿苷激酶的尿苷磷酸化率。尿苷掺入RNA和RNA合成速率之间没有简单的关系，体外测定的尿苷激酶活性在PHA刺激的淋巴细胞中增加，但这种增加至少对于尿苷掺入速率的初始增加是不必要的。淋巴细胞生长受限于低浓度放线菌素或前列腺素E1的研究表明，尿苷激酶活性的升高依赖于尿苷掺入的增加，而不是相反。我们的结论是，正常情况下存在于淋巴细胞中的尿苷激酶的量并不限制尿苷磷酸化的速率，并且完整细胞中的尿苷激酶活性受到酶浓度以外的某些因素的调节，这些结果对研究PHA刺激淋巴细胞过程中RNA代谢的变化具有重要意义，讨论这种考虑可能广泛适用于真核细胞中前体掺入核酸的研究。
The transformation of lymphocytes by PHA is accompanied by a marked increase in the rate of incorporation of3H-uridine into RNA. Nucleosides seem to be the major source of pyrimidine nucleotides in this system, but evidence is presented that uridine incorporation into RNA is limited by the rate of phosphorylation of uridine by uridine kinase. There is no simple relationship between uridine incorporation into RNA and the rate of RNA synthesis.Uridine kinase activity, assayed in vitro, increases in PHA-stimulated lymphocytes, but this increase is not necessary for at least the initial increase in the rate of uridine incorporation. Studies in which lymphocyte growth was limited by low concentrations of actinomycin or prostaglandin E1indicated that the rise in uridine kinase activity was dependent on the increase in uridine incorporation rather than vice-versa. We conclude that the amount of uridine kinase normally present in the lymphocyte does not limit the rate of phosphorylation of uridine, and that uridine kinase activity in the intact cell is subject to regulation by some factor other than the enzyme concentration, possibly the intracellular concentration of pyrimidine triphosphates.The implications of these results for studies on the changes in RNA metabolism during the stimulation of lymphocytes by PHA are discussed. Such considerations may be widely applicable to studies of the incorporation of precursors into nucleic acids in eucaryotic cells.