Howard B V, Howard W J, Kefalides N A
J Cell Physiol. 1976 Oct;89(2):325-36. doi: 10.1002/jcp.1040890215.
Regulation of lipid synthesis from acetate in human diploid fibroblast cultures has been studied at various passage levels and at different stages of cell growth. When cultures were transferred to lipid free medium, a stimulation of [14C]acetate incorporation into lipid occurred within three to six hours after removal of exogenous lipid. In early passage cultures, this stimulation was observed whether cells were transferred to protein-free medium or medium supplemented with delipidized serum protein. However, in late passage cultures the presence of delipidized serum protein was required for the stimulation of lipid synthesis. When logarithmically dividing and stationary phase cultures were compared, the cultures in log phase showed stimulation of acetate incorporation into lipid in the presence or absence of delipidized serum protein, whereas in the stationary cultures the delipidized serum protein was required. When cultures were partially synchronized by a thymidine block, stimulation of acetate incorporation into lipid in the blocked cells only occurred in the presence of delipidized serum protein; in released cells stimulation occurred in protein free medium. When inhibition of lipid synthesis from acetate was compared in young vs. old or dividing vs. stationary cultures, however, no differences were observed. The data indicate the response of diploid fibroblast cultres to change in exogenous lipid is dependent on passage level and state of growth.
在人类二倍体成纤维细胞培养物中，已在不同传代水平和细胞生长的不同阶段研究了从乙酸盐合成脂质的调控。当培养物转移至无脂质培养基时，去除外源脂质后三到六小时内，[14C]乙酸盐掺入脂质的过程受到刺激。在早期传代培养物中，无论细胞是转移至无蛋白培养基还是补充有脱脂血清蛋白的培养基中，均观察到这种刺激。然而，在晚期传代培养物中，刺激脂质合成需要脱脂血清蛋白的存在。当对数生长期和平静期培养物进行比较时，对数期培养物在有或没有脱脂血清蛋白存在的情况下均显示乙酸盐掺入脂质受到刺激，而在静止期培养物中则需要脱脂血清蛋白。当通过胸苷阻断使培养物部分同步化时，仅在存在脱脂血清蛋白的情况下，阻断细胞中乙酸盐掺入脂质才受到刺激；在释放的细胞中，在无蛋白培养基中出现刺激。然而，当比较年轻与年老或分裂与静止培养物中乙酸盐脂质合成的抑制情况时，未观察到差异。数据表明二倍体成纤维细胞培养物对外源脂质变化的反应取决于传代水平和生长状态。
