Tessner T G, Rock C O, Kalmar G B, Cornell R B, Jackowski S
Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105.
J Biol Chem. 1991 Sep 5;266(25):16261-4.
Growth factor regulation of phosphatidylcholine (PtdCho) metabolism during the G1 stage of the cell cycle was investigated in the colony-stimulating factor 1 (CSF-1)-dependent murine macrophage cell-line BAC1.2F5. The transient removal of CSF-1 arrested the cells in G1. Incorporation of [3H]choline into PtdCho was stimulated significantly 1 h after growth factor addition to quiescent cells. Metabolic labeling experiments pointed to CTP:phosphocholine cytidylyltransferase (CT) as the rate-controlling enzyme for PtdCho biosynthesis in BAC1.2F5 cells. The amount of CT mRNA increased 4-fold within 15 min of CSF-1 addition and remained elevated for 2 h. The rise in CT mRNA levels was accompanied by a 50% increase in total CT specific activity in cell extracts within 4 h after the addition of CSF-1. CSF-1-dependent elevation of CT mRNA content was neither attenuated nor superinduced by the inhibition of protein synthesis with cycloheximide. The rate of CT mRNA turnover decreased in the presence of CSF-1 indicating that message stabilization was a key factor in determining the levels of CT mRNA. These data point to increased CT mRNA abundance as a component in growth factor-stimulated PtdCho synthesis.
在集落刺激因子1（CSF-1）依赖性小鼠巨噬细胞系BAC1.2F5中，研究了细胞周期G1期磷脂酰胆碱（PtdCho）代谢的生长因子调控。短暂去除CSF-1会使细胞停滞在G1期。向静止细胞添加生长因子1小时后，[3H]胆碱掺入PtdCho的量显著增加。代谢标记实验表明，CTP：磷酸胆碱胞苷转移酶（CT）是BAC1.2F5细胞中PtdCho生物合成的限速酶。添加CSF-1后15分钟内，CT mRNA的量增加了4倍，并在2小时内保持升高。CT mRNA水平的升高伴随着添加CSF-1后4小时内细胞提取物中总CT比活性增加50%。用环己酰亚胺抑制蛋白质合成既不会减弱也不会超诱导CSF-1依赖性CT mRNA含量的升高。在CSF-1存在下，CT mRNA的周转速率降低，表明信息稳定是决定CT mRNA水平的关键因素。这些数据表明，CT mRNA丰度增加是生长因子刺激PtdCho合成的一个组成部分。
