AN ECDYSTEROID-INDUCIBLE MANDUCA GENE SIMILAR TO THE DROSOPHILA DHR3 GENE, A MEMBER OF THE STEROID-HORMONE RECEPTOR SUPERFAMILY
AN ECDYSTEROID-INDUCIBLE MANDUCA GENE SIMILAR TO THE DROSOPHILA DHR3 GENE, A MEMBER OF THE STEROID-HORMONE RECEPTOR SUPERFAMILY
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DOI：
10.1016/0012-1606(92)90244-b
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发表时间：
1992-04-01
影响因子：
2.7
通讯作者：
RIDDIFORD, LM
中科院分区：
文献类型：
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作者：
PALLI, SR;HIRUMA, K;RIDDIFORD, LM
利用人视黄酸受体α（hRARα）和果蝇激素受体3（DHR 3）的cDNA，我们从烟草天蛾（Manduca sexta）中分离出编码类固醇激素受体超家族成员的cDNA。测序结果显示，该cDNA与DHR 3最密切相关（DNA和配体结合区的氨基酸同一性分别为97%和68%），其次是hRARα（同一性分别为65%和20%），因此命名为MHR 3。的cDNA杂交到两个mRNA（3.8和4.5 kb）发现在表皮蜕皮激素上升的胚胎，幼虫，蛹蜕皮。用4 μ M 20-羟基蜕皮激素（2 μg/ml 20 HE）处理4龄幼虫表皮，3 h内MHR 3 mRNA出现，6 h达高峰，12 h后mRNA水平下降。4.5 kb的mRNA首先出现，到12小时，两者均以等量存在，到20小时，主要转录物为3.8 kb。类似的20 HE诱导的表达被认为是在游走发作后1天，虽然有一个较慢的时间过程中，在表皮中。这种诱导在很大程度上不依赖于蛋白质合成，但随后的下降需要蛋白质合成，这是果蝇“早期”喷气的典型特征。持续暴露于20 HE是必要的MHR 3的表达，在其情况下，mRNA下降的半衰期为2 hr. Thus，MHR 3是一个蜕皮激素诱导的DNA结合蛋白，可能是一个转录因子参与级联的蜕皮激素引起的基因激活和失活在昆虫蜕皮。
Using cDNAs for the human retinoic acid receptor α (hRARα) andDrosophilahormone receptor 3 (DHR3), we isolated a cDNA encoding a member of the steroid hormone receptor superfamily from the tobacco hornworm,Manduca sexta. Sequencing showed that this cDNA is most closely related to DHR3 (97 and 68% amino acid identity in the DNA and ligand binding regions, respectively) followed by hRARα (65 and 20% identity, respectively) and therefore is named MHR3. The cDNA hybridized to two mRNAs (3.8 and 4.5 kb) found in the epidermis during the ecdysteroid rises for the embryonic, larval, and pupal molts. Culture of fourth instar larval epidermis with 4 μM20-hydroxyecdysone (2 μg/ml 20HE) caused the appearance of MHR3 mRNA within 3 hr and maximal expression by 6 hr; after 12 hr continuous exposure to 20HE, the mRNA level declined. The 4.5-kb mRNA appeared first, both were present in equal amounts by 12 hr, and by 20 hr the predominant transcript was 3.8 kb. Similar 20HE-induced expression was seen in epidermis explanted 1 day after the onset of wandering, although with a slower time course. The induction was largely independent of protein synthesis, but the subsequent decline required protein synthesis as is typical of the “early” puffs inDrosophila. Continuous exposure to 20HE was necessary for MHR3 expression; in its absence, the mRNA declined with a half-life of 2 hr. Thus, MHR3 is an ecdysteroid-inducible DNA binding protein that likely is a transcription factor involved in the cascade of gene activation and inactivation caused by ecdysteroids during the insect molt.