School of Life Science and Technology, Tokyo Institute of Technology.
Genes Genet Syst. 2023 Nov 21;98(5):249-257. doi: 10.1266/ggs.23-00188. Epub 2023 Oct 17.
Keratins are intermediate filament proteins that are important for epidermal strength and protection from desiccation. Keratin genes are highly duplicated and have diversified by forming two major clusters in the genomes of terrestrial vertebrates. The keratin genes of lungfishes, the closest fish to tetrapods, have not been studied at the genomic level, despite the importance of lungfishes in terrestrial adaptation. Here, we identified keratin genes in the genomes of two lungfish species and performed syntenic and phylogenetic analyses. Additionally, we identified keratin genes from two gobies and two mudskippers, inhabiting underwater and terrestrial environments. We found that in lungfishes, keratin genes were duplicated and diversified within two major clusters, similar to but independent of terrestrial vertebrates. By contrast, keratin genes were not notably duplicated in mudskippers. The results indicate that keratin gene duplication occurred repeatedly in lineages close to tetrapods, but not in teleost fish, even in species adapted to terrestrial environments.
角蛋白是中间丝蛋白，对表皮强度和防止干燥至关重要。角蛋白基因高度重复，并通过在陆地脊椎动物基因组中形成两个主要簇而多样化。尽管肺鱼在陆地适应中很重要，但肺鱼的角蛋白基因尚未在基因组水平上进行研究。在这里，我们在两种肺鱼的基因组中鉴定了角蛋白基因，并进行了同基因和系统发育分析。此外，我们还从两种虾虎鱼和两种弹涂鱼中鉴定了角蛋白基因，它们分别生活在水下和陆地环境中。我们发现，在肺鱼中，角蛋白基因在两个主要簇内发生了重复和多样化，与陆地脊椎动物相似但独立。相比之下，弹涂鱼中的角蛋白基因没有明显重复。结果表明，角蛋白基因的重复在接近四足动物的谱系中反复发生，但在硬骨鱼中，即使在适应陆地环境的物种中也没有发生。
