Spencer E B, Bianchi A, Widmer J, Witters L A
Department of Medicine, Dartmouth Medical School, Hanover, NH 03755.
Biochem Biophys Res Commun. 1993 Apr 30;192(2):820-5. doi: 10.1006/bbrc.1993.1488.
Acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid synthesis, exists as an oligodendrocyte-associated enzyme in brain and plays an important role in supplying fatty acid for myelination. Rat brain acetyl-CoA carboxylase (ACC) has been identified as a single isozyme of M(r) = 265,000 daltons, indistinguishable immunologically from the isozyme in rat adipose tissue and liver. Total activity of brain ACC declines from birth to 4 weeks of age in the newborn rat. This change in activity can entirely be accounted for by changes in enzyme content, not enzyme specific activity, and is paralleled by decreases in ACC mRNA. In contrast, cardiac, skeletal muscle and liver ACC does not change in content over this developmental period. Unlike ACC in liver and adipose tissue, the enzyme content and specific activity of brain ACC is invariant during various states of nutrition. These data indicate that the brain ACC is subject to unique regulation, as compared to non-neural enzyme. The mechanisms underlying the control of neural ACC activity may be important to understanding the process of myelination during development and to a more general understanding of the factors regulating ACC expression/activity in other tissues.
乙酰辅酶A羧化酶是脂肪酸合成的限速酶，在大脑中作为一种与少突胶质细胞相关的酶存在，并在为髓鞘形成提供脂肪酸方面发挥重要作用。大鼠脑乙酰辅酶A羧化酶（ACC）已被鉴定为一种分子量为265,000道尔顿的单一同工酶，在免疫上与大鼠脂肪组织和肝脏中的同工酶无法区分。新生大鼠脑ACC的总活性从出生到4周龄逐渐下降。这种活性变化完全可以由酶含量的变化来解释，而不是酶的比活性，并且与ACC mRNA的减少平行。相比之下，在这个发育阶段，心脏、骨骼肌和肝脏中的ACC含量没有变化。与肝脏和脂肪组织中的ACC不同，脑ACC的酶含量和比活性在各种营养状态下是不变的。这些数据表明，与非神经酶相比，脑ACC受到独特的调节。控制神经ACC活性的机制可能对于理解发育过程中的髓鞘形成过程以及更全面地理解调节其他组织中ACC表达/活性的因素很重要。
