Boström Malin, Alexson Stefan E H, Lundgren Bo, Nelson B Dean, DePierre Joseph W
Arrhenius Laboratories for the Natural Sciences, Unit of Biochemical Toxicology, Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden.
Prostaglandins Leukot Essent Fatty Acids. 2004 Nov;71(5):319-27. doi: 10.1016/j.plefa.2004.04.008.
Acyl-CoA thioesterases hydrolyze acyl-CoAs to free fatty acids and CoASH, thereby regulating fatty acid metabolism. This activity is catalyzed by numerous structurally related and unrelated enzymes, of which several acyl-CoA thioesterases have been shown to be regulated via the peroxisome proliferator-activated receptor alpha, strongly linking them to fatty acid metabolism. Two protein families have recently been characterized, the type I acyl-CoA thioesterase gene family and the type II protein family, which are expressed in cytosol, mitochondria and peroxisomes. Still, only little is known about regulation of their expression and precise functions in vivo. In the present study, we have investigated the activity and expression of acyl-CoA thioesterase in the porcine ovary during different phases of the estrus cycle. The activity was low in homogenates obtained during the immature and follicular phases, increasing nearly 4-fold during the luteal phase, with the highest activity being found in the pregnant corpus luteum (about 7-fold higher than in immature follicles). The increase in homogenate activity in corpus luteum from pregnant pigs was due to a moderate increase in the cytosolic activity, and an approximately 20-25-fold increase in the mitochondrial fraction. Western blot analysis showed no detectable expression of the type I acyl-CoA thioesterases (CTE-I and MTE-I) and revealed that the increased activity in cytosol and mitochondria is due to increased expression of the type II acyl-CoA thioesterases (CTE-II and MTE-II). This apparent hormonal regulation of expression of the type II acyl-CoA thioesterase may provide new insights into the functions of these enzymes in the mammalian ovary.
酰基辅酶A硫酯酶将酰基辅酶A水解为游离脂肪酸和辅酶A，从而调节脂肪酸代谢。这种活性由多种结构相关和不相关的酶催化，其中几种酰基辅酶A硫酯酶已被证明通过过氧化物酶体增殖物激活受体α进行调节，这使它们与脂肪酸代谢紧密相连。最近鉴定出了两个蛋白质家族，即I型酰基辅酶A硫酯酶基因家族和II型蛋白质家族，它们在细胞质、线粒体和过氧化物酶体中表达。然而，关于它们在体内的表达调控和精确功能仍知之甚少。在本研究中，我们研究了发情周期不同阶段猪卵巢中酰基辅酶A硫酯酶的活性和表达。在未成熟和卵泡期获得的匀浆中活性较低，在黄体期增加近4倍，在妊娠黄体中活性最高（比未成熟卵泡高约7倍）。妊娠母猪黄体匀浆活性的增加是由于细胞质活性适度增加，线粒体部分增加约20 - 25倍。蛋白质印迹分析未检测到I型酰基辅酶A硫酯酶（CTE - I和MTE - I）的表达，并表明细胞质和线粒体中活性的增加是由于II型酰基辅酶A硫酯酶（CTE - II和MTE - II）表达增加所致。II型酰基辅酶A硫酯酶表达的这种明显的激素调节可能为这些酶在哺乳动物卵巢中的功能提供新的见解。
