Casals N, Buesa C, Piulachs M D, Cabañó J, Marrero P F, Bellés X, Hegardt F G
Unit of Biochemistry, University of Barcelona, School of Pharmacy, Spain.
Insect Biochem Mol Biol. 1996 Sep-Oct;26(8-9):837-43. doi: 10.1016/s0965-1748(96)00044-6.
Levels of mRNA for the two 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthases, (HMG-S1 and HMG-S2), and for HMG-CoA reductase (HMG-R) of Blattella germanica were analyzed in the fat body during the first gonadotrophic cycle. HMG-S2 and HMG-R showed the highest mRNA levels on day 0 and decreased thereafter, whereas HMG-S1, showed faint expression. Western blot using specific antibodies for HMG-S1 and HMG-S2 showed no detectable levels for HMG-S1 but a clear pattern for HMG-S2. Both results point to a very limited role for HMG-CoA synthase-1 in B. germanica fat body that the functional enzyme in this organ is HMG-CoA synthase-2. HMG-CoA reductase and synthase proteins shared a cyclic pattern (maximum levels at day 4 and minimum levels on days 0 and 8), which was coincident with the pattern of activity. The delay between gene transcription and protein synthesis suggests a finely regulated translation mechanism. Moreover, the pattern of mevalonate synthesis parallels that of vitellogenin production, suggesting a coordinate mechanism between the mevalonate pathway and the production of vitellogenin.
在第一个促性腺周期中，分析了德国小蠊脂肪体中两种3-羟基-3-甲基戊二酰辅酶A（HMG-CoA）合酶（HMG-S1和HMG-S2）以及HMG-CoA还原酶（HMG-R）的mRNA水平。HMG-S2和HMG-R在第0天显示出最高的mRNA水平，此后下降，而HMG-S1表达微弱。使用针对HMG-S1和HMG-S2的特异性抗体进行的蛋白质印迹分析显示，未检测到HMG-S1的水平，但HMG-S2有明显的表达模式。这两个结果都表明HMG-CoA合酶-1在德国小蠊脂肪体中的作用非常有限，该器官中的功能酶是HMG-CoA合酶-2。HMG-CoA还原酶和合成酶蛋白呈现出周期性模式（第4天达到最高水平，第0天和第8天达到最低水平），这与活性模式一致。基因转录和蛋白质合成之间的延迟表明存在精细调节的翻译机制。此外，甲羟戊酸合成模式与卵黄蛋白原产生模式相似，表明甲羟戊酸途径与卵黄蛋白原产生之间存在协调机制。
