Integrative Genomics Laboratory, Department of Morphology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, Sao Paulo, Brazil.
Heredity (Edinb). 2013 Jul;111(1):57-65. doi: 10.1038/hdy.2013.19. Epub 2013 Apr 3.
The Foxl2 (forkhead box L2) gene is an important member of the forkhead domain family, primarily responsible for the development of ovaries during female sex differentiation. The evolutionary studies conducted previously considered the presence of paralog Foxl2 copies only in teleosts. However, to search for possible paralog copies in other groups of vertebrates and ensure that all predicted copies were homolog to the Foxl2 gene, a broad evolutionary analysis was performed, based on the forkhead domain family. A total of 2464 sequences for the forkhead domain were recovered, and subsequently, 64 representative sequences for Foxl2 were used in the evolutionary analysis of this gene. The most important contribution of this study was the discovery of a new subgroup of Foxl2 copies (ortholog to Foxl2B) present in the chondrichthyan Callorhinchus milii, in the coelacanth Latimeria chalumnae, in the avian Taeniopygia guttata and in the marsupial Monodelphis domestica. This new scenario indicates a gene duplication event in an ancestor of gnathostomes. Furthermore, based on the analysis of the syntenic regions of both Foxl2 copies, the duplication event was not exclusive to Foxl2. Moreover, the duplicated copy distribution was shown to be complex across vertebrates, especially in tetrapods, and the results strongly support a loss of this copy in eutherian species. Finally, the scenario observed in this study suggests an update for Foxl2 gene nomenclature, extending the actual suggested teleost naming of Foxl2A and Foxl2B to all vertebrate sequences and contributing to the establishment of a new evolutionary context for the Foxl2 gene.
Foxl2（叉头框 L2）基因是叉头框结构域家族的重要成员，主要负责雌性性别分化过程中卵巢的发育。之前的进化研究仅认为存在于硬骨鱼中的 Foxl2 基因的旁系同源拷贝。然而，为了在其他脊椎动物群体中寻找可能的旁系同源拷贝，并确保所有预测的拷贝都与 Foxl2 基因同源，我们进行了广泛的进化分析，基于叉头框结构域家族。总共回收了 2464 个叉头域序列，随后，使用 64 个代表 Foxl2 的序列进行了该基因的进化分析。这项研究的最重要贡献是发现了软骨鱼 Callorhinchus milii、腔棘鱼 Latimeria chalumnae、禽类 Taeniopygia guttata 和有袋类 Monodelphis domestica 中 Foxl2 基因的新亚群（与 Foxl2B 同源）。这一新情景表明在颌索动物的祖先中发生了基因复制事件。此外，基于两个 Foxl2 拷贝的共线性区域分析，该复制事件不是 Foxl2 所特有的。此外，复制拷贝的分布在整个脊椎动物中非常复杂，尤其是在四足动物中，结果强烈支持该拷贝在真兽类物种中的丢失。最后，本研究中观察到的情景表明需要更新 Foxl2 基因命名法，将实际建议的硬骨鱼命名法 Foxl2A 和 Foxl2B 扩展到所有脊椎动物序列，并有助于为 Foxl2 基因建立新的进化背景。
