Chung A C, Durica D S, Clifton S W, Roe B A, Hopkins P M
Department of Zoology, University of Oklahoma, Norman 73019, USA.
Mol Cell Endocrinol. 1998 Apr 30;139(1-2):209-27. doi: 10.1016/s0303-7207(98)00056-2.
We report the cloning and analysis of ecdysteroid receptor (bpEcR) and retinoid-X receptor (UpRXR) cDNA homologs from the fiddler crab Uca pugilator. The deduced amino acid sequence of this crustacean EcR most closely resembles the insect EcRs within the DNA binding and ligand binding domains (LBDs). For UpRXR, the DNA binding domain (DBD) shares greatest identity to the insect USPs. The ligand binding domain, however, is closer to vertebrate RXRs but may have a nonfunctional AF-2 domain. Probes derived from these clones were used to examine transcript levels in blastemas during early limb regeneration. Both UpEcR and UpRXR transcripts were detected in low amounts 1 day after limb loss, but increased during the next 4 days. Immersion of crabs in sea water containing all-trans retinoic acid increased the steady state concentrations of UpRXR transcript and altered the pattern of circulating ecdysteroids. These effects correlate with the disruptive effects of retinoic acid on blastemal differentiation observed in earlier studies.
我们报道了来自招潮蟹（Uca pugilator）的蜕皮类固醇受体（bpEcR）和类视黄醇X受体（UpRXR）cDNA同源物的克隆与分析。该甲壳类动物EcR的推导氨基酸序列在DNA结合域和配体结合域（LBD）内与昆虫EcR最为相似。对于UpRXR，其DNA结合域（DBD）与昆虫USP的同源性最高。然而，其配体结合域更接近脊椎动物的RXR，但可能有一个无功能的AF-2结构域。从这些克隆中获得的探针用于检测肢体早期再生过程中芽基中的转录水平。肢体缺失1天后，UpEcR和UpRXR转录本的含量均较低，但在接下来的4天中有所增加。将螃蟹浸入含有全反式维甲酸的海水中，可增加UpRXR转录本的稳态浓度，并改变循环蜕皮类固醇的模式。这些效应与早期研究中观察到的维甲酸对芽基分化的破坏作用相关。
