Martinez-Lamparero Ana, Casero Marie-Carmen, Ortiz-Caro Javier, Sastre Leandro
Instituto de Investigaciones Biomédicas CSIC/UAM, C/ Arturo Duperier No. 4, 28029 Madrid, Spain.
J Exp Biol. 2003 May;206(Pt 9):1565-73. doi: 10.1242/jeb.00285.
Artemia franciscana embryos can suspend their development and metabolism at the gastrula stage to enter a state of cryptobiosis, forming cysts. Embryonic development and metabolism can be resumed under favorable environmental conditions to give rise to free-swimming larvae or nauplii. The mechanisms that mediate these processes are not completely known. Here, we report our studies of the mechanisms that regulate transcriptional activation upon exiting cryptobiosis. Regulatory regions of several A. franciscana gene promoters were identified. Functional analyses in mammalian cells allowed the identification of transcriptional activator regions in the Actin302 promoter and in promoter 2 of the sarco/endoplasmic reticulum Ca(2+)-ATPase-encoding gene. These regions were shown to specifically bind protein factors from nuclear extracts of A. franciscana nauplii by means of electrophoretic mobility shift assays. Several protein-binding regions were also detected by DNase I protection analysis in the promoters of the genes encoding the alpha1 subunit of Na(+)/K(+)-ATPase, actin 302 and sarco/endoplasmic reticulum Ca(2+)-ATPase. Specific DNA-binding proteins in nauplius nuclear extracts were detected for all the promoter regions analyzed. These proteins were either not present in cyst nuclear extracts or were present in much smaller concentrations. Three of the five regions analyzed also bound proteins present in cyst nuclear extracts. These data indicate that transcriptional activation upon exiting cryptobiosis in A. franciscana involves the expression/activation of DNA-binding transcription factors that are not present in cyst nuclei
卤虫胚胎能够在原肠胚阶段暂停其发育和新陈代谢，进入隐生状态，形成包囊。在适宜的环境条件下，胚胎发育和新陈代谢可以恢复，从而产生自由游动的幼虫或无节幼体。介导这些过程的机制尚未完全明确。在此，我们报告了关于调控隐生状态解除后转录激活机制的研究。我们鉴定了几种卤虫基因启动子的调控区域。在哺乳动物细胞中的功能分析使得我们能够在肌动蛋白302启动子以及编码肌浆/内质网Ca(2+)-ATP酶的基因的启动子2中鉴定出转录激活区域。通过电泳迁移率变动分析表明，这些区域能够特异性结合来自卤虫无节幼体核提取物中的蛋白质因子。在编码Na(+)/K(+)-ATP酶α1亚基、肌动蛋白302和肌浆/内质网Ca(2+)-ATP酶的基因启动子中，通过DNase I保护分析也检测到了几个蛋白质结合区域。对于所有分析的启动子区域，均在无节幼体核提取物中检测到了特异性DNA结合蛋白。这些蛋白质要么不存在于包囊核提取物中，要么浓度低得多。在分析的五个区域中，有三个区域也结合了包囊核提取物中存在的蛋白质。这些数据表明，卤虫隐生状态解除后的转录激活涉及到包囊核中不存在的DNA结合转录因子的表达/激活。
