Hauff Kristin, Linda Dorota, Hatch Grant M
Department of Pharmacology and Therapeutics, Center for Research and Treatment of Atherosclerosis, Center on Aging, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
Biochem J. 2009 Jan 15;417(2):573-82. doi: 10.1042/BJ20080650.
CL (cardiolipin) is a key phospholipid involved in ATP generation. Since progression through the cell cycle requires ATP we examined regulation of CL synthesis during S-phase in human cells and investigated whether CL or CL synthesis was required to support nucleotide synthesis in S-phase. HeLa cells were made quiescent by serum depletion for 24 h. Serum addition resulted in substantial stimulation of [methyl-(3)H]thymidine incorporation into cells compared with serum-starved cells by 8 h, confirming entry into the S-phase. CL mass was unaltered at 8 h, but increased 2-fold by 16 h post-serum addition compared with serum-starved cells. The reason for the increase in CL mass upon entry into S-phase was an increase in activity and expression of CL de novo biosynthetic and remodelling enzymes and this paralleled the increase in mitochondrial mass. CL de novo biosynthesis from D-[U-(14)C]glucose was elevated, and from [1,3-(3)H]glycerol reduced, upon serum addition to quiescent cells compared with controls and this was a result of differences in the selection of precursor pools at the level of uptake. Triascin C treatment inhibited CL synthesis from [1-(14)C]oleate but did not affect [methyl-(3)H]thymidine incorporation into HeLa cells upon serum addition to serum-starved cells. Barth Syndrome lymphoblasts, which exhibit reduced CL, showed similar [methyl-(3)H]thymidine incorporation into cells upon serum addition to serum-starved cells compared with cells from normal aged-matched controls. The results indicate that CL de novo biosynthesis is up-regulated via elevated activity and expression of CL biosynthetic genes and this accounted for the doubling of CL seen during S-phase; however, normal de novo CL biosynthesis or CL itself is not essential to support nucleotide synthesis during entry into S-phase of the human cell cycle.
心磷脂（CL）是参与ATP生成的关键磷脂。由于细胞周期的进程需要ATP，我们研究了人类细胞S期CL合成的调控，并调查了S期支持核苷酸合成是否需要CL或CL合成。通过血清饥饿24小时使HeLa细胞进入静止期。与血清饥饿细胞相比，添加血清8小时后，[甲基 - （3）H]胸苷掺入细胞的量显著增加，证实细胞进入S期。8小时时CL质量未改变，但与血清饥饿细胞相比，添加血清16小时后CL质量增加了2倍。进入S期时CL质量增加的原因是CL从头生物合成和重塑酶的活性及表达增加，这与线粒体质量的增加平行。与对照相比，向静止细胞添加血清后，由D - [U - （14）C]葡萄糖进行的CL从头生物合成增加，而由[1,3 - （3）H]甘油进行的CL从头生物合成减少，这是摄取水平上前体池选择差异的结果。三嗪菌素C处理抑制了[1 - （14）C]油酸酯合成CL，但在向血清饥饿细胞添加血清后不影响[甲基 - （3）H]胸苷掺入HeLa细胞。与年龄匹配的正常对照细胞相比，表现出CL减少的Barth综合征淋巴母细胞在向血清饥饿细胞添加血清后，[甲基 - （3）H]胸苷掺入细胞的情况相似。结果表明，CL从头生物合成通过CL生物合成基因活性和表达的升高而上调，这解释了S期CL翻倍的现象；然而，正常的CL从头生物合成或CL本身对于支持人类细胞周期进入S期时的核苷酸合成并非必不可少。
