Bizzozero O A, Sanchez P, Tetzloff S U
Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque 87131-5218, USA.
J Neurochem. 1999 Jun;72(6):2610-6. doi: 10.1046/j.1471-4159.1999.0722610.x.
The present study was designed to determine whether the palmitoylation of the hydrophobic myelin proteolipid protein (PLP) is dependent on cellular energy. To this end, brain slices from 20- and 60-day-old rats were incubated with [3H]palmitate for 1 h in the presence or absence of various metabolic poisons. In adult rats, the inhibition of mitochondrial ATP production with KCN (5 mM), oligomycin (10 microM), or rotenone (10 microM) reduced the incorporation of [3H]palmitate into fatty acyl-CoA and glycerolipids by 50-60%, whereas the labeling of PLP was unaltered. Incubation in the presence of rotenone (10 microM) plus NaF (5 mM) abolished the synthesis of acyl-CoA and lipid palmitoylation, but the incorporation of [3H]palmitate into PLP was still not different from that in controls. In rapidly myelinating animals, the inhibition of both mitochondrial electron transport and glycolysis obliterated the palmitoylation of lipids but reduced that of PLP by only 40%. PLP acylation was reduced to a similar extent when slices were incubated for up to 3 h, indicating that exogenously added palmitate is incorporated into PLP by ATP-dependent and ATP-independent mechanisms. Determination of the number of PLP molecules modified by each of these reactions during development suggests that the ATP-dependent process is important during the formation and/or compaction of the myelin sheath, whereas the ATP-independent mechanism is likely to play a role in myelin maintenance, perhaps by participating in the periodic repair of thioester linkages between the fatty acids and the protein.
本研究旨在确定疏水的髓鞘蛋白脂蛋白（PLP）的棕榈酰化是否依赖于细胞能量。为此，将20日龄和60日龄大鼠的脑片在存在或不存在各种代谢毒物的情况下与[3H]棕榈酸孵育1小时。在成年大鼠中，用KCN（5 mM）、寡霉素（10 microM）或鱼藤酮（10 microM）抑制线粒体ATP生成可使[3H]棕榈酸掺入脂肪酰辅酶A和甘油脂质的量减少50 - 60%，而PLP的标记未改变。在鱼藤酮（10 microM）加NaF（5 mM）存在下孵育消除了酰基辅酶A的合成和脂质的棕榈酰化，但[3H]棕榈酸掺入PLP的量仍与对照组无异。在快速髓鞘形成的动物中，线粒体电子传递和糖酵解均受抑制时消除了脂质的棕榈酰化，但PLP的棕榈酰化仅减少40%。当脑片孵育长达3小时时，PLP酰化减少到类似程度，表明外源添加的棕榈酸通过ATP依赖和ATP非依赖机制掺入PLP。对发育过程中经这些反应修饰的PLP分子数量的测定表明，ATP依赖过程在髓鞘形成和/或压实过程中很重要，而ATP非依赖机制可能在髓鞘维持中起作用，也许是通过参与脂肪酸与蛋白质之间硫酯键的周期性修复。
