七鳃鳗KCTD基因家族成员全基因组鉴定及进化分析

Genome-wide Identification of KCTD Gene Family in Lampreys and Its Evolutionary Analysis

钾离子通道四聚化结构域(KCTD)蛋白基因家族是一个保守的基因家族,该家族成员的共同特征是具有一个含有BTB保守结构域的N-末端和一个可变的C-末端。KCTD基因的突变或不正常调控与人类多种疾病相关。七鳃鳗是现存最原始的脊椎动物,作为联系无脊椎动物和脊椎动物之间的桥梁,在生物进化研究中占有重要地位。本研究通过对海七鳃鳗(Petromyzon marinus)和日本七鳃鳗(Lethenteron japonicum)基因组和转录组数据分析,全面系统地鉴定了海七鳃鳗和日本七鳃鳗KCTD基因家族成员,并对其基因结构特征、蛋白保守基序和基因表达模式进行了分析。在海七鳃鳗和日本七鳃鳗中分别鉴定出13个和14个KCTD基因,基因长度和外显子数目在不同KCTD基因间变化很大,KCTD蛋白中4个基序保守性显著,大多数KCTD基因呈泛表达模式,并且在胚胎发育时期明显高表达。除七鳃鳗外,对12个无脊椎动物和脊椎动物代表物种KCTD基因家族成员进行了鉴定,并对KCTD基因家族成员的进化关系进行了分析。根据进化树聚类情况,将KCTD基因家族成员分为11个亚家族。进化分析结果显示,KCTD基因家族从低等的无脊椎动物线虫和果蝇到高等的人类都存在;线虫中仅有5个成员,果蝇中有8个成员,随着物种进化程度由低到高,KCTD家族成员数目呈现增加的趋势;从爬行类开始,脊椎动物KCTD基因数目稳定在24个左右。硬骨鱼类特有的全基因组复制事件影响鱼类KCTD基因数目。本研究结果不仅丰富了七鳃鳗KCTD基因家族信息,同时也对KCTD家族基因间的进化关系进行了探究,为深入研究该家族基因功能提供了一定的依据。

The KCTD(potassium channel tetramerization domain)proteins belong to a conserved gene family with its proteins containing a conserved BTB domain at N-terminal and a flexible C-terminal.Mutations or improper regulation of KCTD genes are associated with diverse diseases in human.Lampreys,the most primitive vertebrates in existence,played an important role in the study of animal evolution as a bridge over invertebrates and vertebrates.In this study,by analyzing the genomic and transcriptional data of Petromyzon marinus and Lethenteron japonicum,we comprehensively and systematically identified the KCTD gene family members of Petromyzon marinus and Lethenteron japonicum,and we analyzed their gene structure characteristics,protein conserved motifs and gene expression patterns.We identified 13 and14 KCTD gene members in Petromyzon marinus and Lethenteron japonicum genomic resources,respectively.The gene length and the number of exons are varied significantly among different KCTD genes.The conservation of 4 motifs in Kctd proteins is significant.Most members of KCTD genes are widely and highly expressed during embryonic development stages.In addition to lamprey,we also identified the KCTD genes in other 12 representative species from invertebrates and vertebrates and constructed a phylogenetic tree of KCTD gene family,and analyzed the evolutionary relationship between KCTD gene family members.The KCTD gene family was classified into eleven subfamilies based on the circumstances of evolutionary tree clustering.The results evolutionary analysis demonstrated that KCTD gene family is existed conservatively from lower invertebrates nematodes and fruit flies to higher humans.Nematode and Fruitfly have 5 and 8 members,respectively.During the progress of species evolution,from lower to higher organisim,the number of KCTD genes was increased.The vertebrates possess about 24 KCTD gene family members since the appearance of reptiles.In fish,the number of KCTD gene family was influenced by the teleost-specific whole genome duplication event.This study not only enriched the KCTD gene family information in lampreys and explored the phylogenetic relationship between different KCTD members,but also provided a reference for the functional study of KCTD genes in the future.