CHANGES IN GENERAL AND SPECIFIC PROTEIN-SYNTHESIS THAT ACCOMPANY ECDYSTEROID SYNTHESIS IN STIMULATED PROTHORACIC GLANDS OF MANDUCA-SEXTA
CHANGES IN GENERAL AND SPECIFIC PROTEIN-SYNTHESIS THAT ACCOMPANY ECDYSTEROID SYNTHESIS IN STIMULATED PROTHORACIC GLANDS OF MANDUCA-SEXTA
复制标题
DOI：
10.1016/0965-1748(94)90084-1
复制
发表时间：
1994-02-01
影响因子：
3.8
通讯作者：
GILBERT, LI
中科院分区：
文献类型：
--
作者：
RYBCZYNSKI, R;GILBERT, LI
五龄雄性曼都卡幼虫的前胸腺对脑神经肽促胸激素（pth）的刺激有反应，其外泌激素的合成速度增加数倍。先前的研究表明，这种反应需要蛋白质合成，并且PTTH的作用可以被二丁基cAMP （dbcAMP）和Ca2+离子载体A23187模拟。为了进一步了解蛋白质合成在前胸腺对甲状旁腺的反应中的作用，我们使用[S-35]蛋氨酸体外培养的腺体来检测受刺激腺体中蛋白质合成的模式。这三种药物均引起体外类固醇合成速率的增加，并且在刺激后2小时内，三种蛋白质（p100、p70和p50）的合成和/或积累增加高达300%。这三种蛋白质的变化是前胸腺特有的，不是由非脑肽引起的，也不仅仅是腺体中一般蛋白质合成增加的结果。腺体单独暴露于A23187，或同时暴露于dbcAMP，可导致p100、p70、p50和表皮甾体的合成增加，但降低一般蛋白质的合成。在启动PTTH刺激后的15分钟内，可以检测到这些蛋白质的合成增加。这三种蛋白的行为使它们成为前胸腺外甾体合成调节剂的候选者。结果还表明，甲状旁腺激素可能激活腺体内的两条生化途径：一条途径导致p100、p70和p50蛋白合成增加，并增加外皮甾体合成；另一条途径导致一般蛋白合成增加。这第二营养效应是脆弱的细胞内Ca2+变化，不抑制第一途径。
The prothoracic glands of fifth instar Manduca sexta larvae respond to stimulation by the brain neuropeptide, prothoracicotropic hormone (PTTH), with a several-fold increase in the rate of ecdysteroid synthesis. Previous studies have shown that this response requires protein synthesis and that the action of PTTH can be mimicked by dibutyryl cAMP (dbcAMP) and the Ca2+ ionophore, A23187. To further understand the role of protein synthesis in the response of prothoracic glands to PTTH, patterns of protein synthesis in stimulated glands were examined using glands incubated in vitro with [S-35]methionine. All three agents caused an increase in the rate of ecdysteroid synthesis as well as an increase of up to 300% in the synthesis and/or accumulation of three proteins (p100, p70, and p''50'') within 2 h of stimulation. Changes in these three proteins were specific to the prothoracic gland, were not elicited by non-brain peptides and were not simply a result of increased general protein synthesis in the gland. Exposure of the glands to A23187 alone, or concurrently with dbcAMP, resulted in increased synthesis of p100, p70, p''50'' and ecdysteroids but decreased general protein synthesis. Increased synthesis of these proteins could be detected within 15 min after initiating PTTH stimulation. The behavior of these three proteins makes them candidates for modulators of ecdysteroid synthesis in the prothoracic gland. The results suggest also that PTTH may activate two biochemical pathways in the gland: one path leading to increased synthesis of the p100, p70, and p''50'' proteins and increased ecdysteroid synthesis, and the second leading to increased general protein synthesis. This second trophic effect is vulnerable to intracellular Ca2+ changes that do not inhibit the first pathway.