Toyomizu Masaaki, Ueda Masatoshi, Sato Shinichi, Seki Yoshinori, Sato Kan, Akiba Yukio
Science of Biological Function, Life Science, Graduate School of Agriculture, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
FEBS Lett. 2002 Oct 9;529(2-3):313-8. doi: 10.1016/s0014-5793(02)03395-1.
Although bird species studied thus far have no distinct brown adipose tissue (BAT) or a related thermogenic tissue, there is now strong evidence that non-shivering mechanisms in birds may play an important role during cold exposure. Recently, increased expression of the duckling homolog of the avian uncoupling protein (avUCP) was demonstrated in cold-acclimated ducklings [Raimbault et al., Biochem. J. 353 (2001) 441-444]. Among the mitochondrial anion carriers, roles for the ATP/ADP antiporter (ANT) as well as UCP variants in thermogenesis are proposed. The present experiments were conducted (i) to examine the effects of cold acclimation on the fatty acid-induced uncoupling of oxidative phosphorylation in skeletal muscle mitochondria and (ii) to clone the cDNA of UCP and ANT homologs from chicken skeletal muscle and study differences compared to controls in expression levels of their mRNAs in the skeletal muscle of cold-acclimated chickens. The results obtained here show that suppression of palmitate-induced uncoupling by carboxyatractylate was greater in the subsarcolemmal skeletal muscle mitochondria from cold-acclimated chickens than that for control birds. An increase in mRNA levels of avANT and, to lesser degree, of avUCP in the skeletal muscle of cold-acclimated chickens was also found. Taken together, the present studies on cold-acclimated chickens suggest that the simultaneous increments in levels of avANT and avUCP mRNA expression may be involved in the regulation of thermogenesis in skeletal muscle.
尽管迄今为止所研究的鸟类物种没有明显的棕色脂肪组织（BAT）或相关的产热组织，但现在有强有力的证据表明，鸟类的非颤抖机制在冷暴露期间可能发挥重要作用。最近，在冷适应的雏鸭中证实了鸟类解偶联蛋白（avUCP）的雏鸭同源物表达增加[兰博尔特等人，《生物化学杂志》353（2001）441 - 444]。在线粒体阴离子载体中，有人提出ATP/ADP反向转运体（ANT）以及UCP变体在产热中发挥作用。进行本实验的目的是：（i）研究冷适应对骨骼肌线粒体中脂肪酸诱导的氧化磷酸化解偶联的影响；（ii）从鸡骨骼肌中克隆UCP和ANT同源物的cDNA，并研究与对照组相比，冷适应鸡骨骼肌中它们的mRNA表达水平的差异。此处获得的结果表明，在冷适应鸡的肌膜下骨骼肌线粒体中，羧基苍术苷对棕榈酸酯诱导的解偶联的抑制作用比对对照鸟类更强。还发现冷适应鸡骨骼肌中avANT的mRNA水平有所增加，而avUCP的增加程度较小。综上所述，目前对冷适应鸡的研究表明，avANT和avUCP mRNA表达水平的同时增加可能参与骨骼肌产热的调节。
