Differential expression patterns of the two paralogous Rec8 from Nile tilapia and their responsiveness to retinoic acid signaling
Differential expression patterns of the two paralogous Rec8 from Nile tilapia and their responsiveness to retinoic acid signaling
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DOI：
10.1016/j.cbpb.2021.110563
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发表时间：
2021-01-25
影响因子：
2.2
通讯作者：
Wei, Jing
中科院分区：
文献类型：
--
作者：
Luo, Yubing;Wang, Jie;Wei, Jing
REC 8（减数分裂重组蛋白8）是减数分裂凝聚复合体的重要组成部分。有趣的是，两个旁系同源的rec 8基因恰好存在于stra 8（由视黄酸基因8刺激）-缺失的鱼类中，而不是stra 8-存在的鱼类中。Stra 8通常被认为是RA（retinoic acid）介导的哺乳动物减数分裂起始的先决条件。然而，RA如何触发减数分裂的stra 8缺失的鱼类，如尼罗罗非鱼（Oreochromis niloticus）仍然是一个谜。在这里，我们的特点是两个旁系同源rec 8基因在尼罗罗非鱼（Onrec 8a和Onrec 8b），并研究其表达模式和响应RA信号处理离体睾丸培养和启动子荧光素酶报告分析。OnRec 8a和OnRec 8b彼此共享36%的同一性，并且是REC 8的真正直系同源物。它们的表达主要局限于减数分裂生殖细胞的差异时空模式。在精子发生过程中，OnRec 8b主要在60 dah（孵化后天数）的精母细胞中表现出核表达，而OnRec 8a从90 dah开始表现出细胞质表达。在卵子发生过程中，OnRec 8a从30 dah开始表达，而OnRec 8b从90 dah开始表达。进一步的研究表明，RA信号可以上调Onrec 8a和Onrec 8b的表达。总的来说，我们的数据表明OnRec 8a和OnRec 8b可能在减数分裂过程中具有不同的功能，并参与RA介导的减数分裂程序。
REC8 (meiotic recombination protein 8) is an essential component of meiotic cohesion complexes. Interestingly, two paralogous rec8 genes happen to exist in the stra8 (stimulated by retinoic acid gene 8)-absent fishes but not in stra8-existing fishes. Stra8 is usually considered as the prerequirement during RA (retinoic acid)-mediated meiosis initiation in mammals. However, how RA triggers meiosis in the stra8-absent fishes just like Nile tilapia (Oreochromis niloticus) remains elusive. Here we characterized the two paralogous rec8 genes in Nile tilapia (Onrec8a and Onrec8b), and investigated their expression patterns and responsiveness to RA signaling by treatment of ex vivo testicular culture and promoter luciferase reporter assay. OnRec8a and OnRec8b share 36% identity to each other and are true orthologs of REC8. Their expression was predominantly restricted to meiotic germline cells with differential spatiotemporal patterns. During spermatogenesis, OnRec8b predominantly exhibited nuclear expression in spermatocytes from 60 dah (days after hatching), while OnRec8a exhibited cytoplasmic expression from 90 dah. During oogenesis, OnRec8a was expressed from 30 dah, while OnRec8b from 90 dah. Further study shows that RA signaling could upregulate the expression of both Onrec8a and Onrec8b. Collectively, our data implies that OnRec8a and OnRec8b might have differential function during meiosis and be involved in RA-mediated meiosis program.