Faculty of Science Hokkaido University Sapporo, Japan.
Graduate School of Life Science Hokkaido University Sapporo, Japan.
J Steroid Biochem Mol Biol. 2023 Apr;228:106249. doi: 10.1016/j.jsbmb.2023.106249. Epub 2023 Jan 13.
Lampreys are jawless fish that evolved about 550 million years ago at the base of the vertebrate line. Modern lampreys contain a corticoid receptor (CR), the common ancestor of the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR), which first appear in cartilaginous fish, such as sharks. Until recently, 344 amino acids at the amino terminus of adult lamprey CR were not present in the lamprey CR sequence in GenBank. A search of the recently sequenced lamprey germline genome identified two CR sequences, CR1 and CR2, containing the 344 previously un-identified amino acids. CR1 also contains a novel four amino acid insertion in the DNA-binding domain (DBD). We studied corticosteroid and progesterone activation of CR1 and CR2 and found their strongest response was to 11-deoxycorticosterone and 11-deoxycortisol, the two circulating corticosteroids in lamprey. Based on steroid specificity, both CRs are close to elephant shark MR and distant from elephant shark GR. HEK293 cells that were transfected with full-length CR1 or CR2 and the MMTV promoter have about 3-fold higher steroid-mediated activation compared to HEK293 cells transfected with these CRs and the TAT3 promoter. Deletion of the amino-terminal domain (NTD) of lamprey CR1 and CR2 to form truncated CRs decreased transcriptional activation by about 70% in HEK293 cells that were transfected with MMTV, but increased transcription by about 6-fold in cells transfected with TAT3. This indicated that the promoter has an important effect on NTD regulation of transcriptional activation of the CR by steroids. Our results also indicate that the entire lamprey CR sequence is needed for an accurate determination of steroid-mediated transcription.
七鳃鳗是一种无颚鱼类，大约在 5.5 亿年前在脊椎动物的基础上进化而来。现代七鳃鳗含有一种皮质激素受体（CR），是糖皮质激素受体（GR）和盐皮质激素受体（MR）的共同祖先，这两种受体首先出现在软骨鱼类，如鲨鱼中。直到最近，GenBank 中库氏七鳃鳗 CR 序列中仍缺少成熟七鳃鳗 CR 氨基末端的 344 个氨基酸。对最近测序的七鳃鳗生殖系基因组的搜索确定了两个 CR 序列，CR1 和 CR2，它们含有之前未识别的 344 个氨基酸。CR1 还在 DNA 结合域（DBD）中含有一个新的四氨基酸插入。我们研究了皮质激素和孕酮对 CR1 和 CR2 的激活作用，发现它们对 11-脱氧皮质酮和 11-脱氧皮质醇的反应最强，这两种激素是七鳃鳗循环中的两种皮质激素。根据甾体特异性，这两种 CR 都与象鲨 MR 接近，而与象鲨 GR 较远。用全长 CR1 或 CR2 和 MMTV 启动子转染的 HEK293 细胞的甾体介导的激活比用这些 CR 和 TAT3 启动子转染的 HEK293 细胞高约 3 倍。库氏七鳃鳗 CR1 和 CR2 的氨基末端结构域（NTD）缺失形成截短的 CR，在转染 MMTV 的 HEK293 细胞中降低转录激活约 70%，但在转染 TAT3 的细胞中增加转录约 6 倍。这表明启动子对甾体调节 CR 转录激活的 NTD 有重要影响。我们的结果还表明，需要完整的七鳃鳗 CR 序列才能准确确定甾体介导的转录。
