摘要
ParaHox genes (Gsx, Pdx, and Cdx) are an ancient family of developmental genes closely related to the Hox genes. They play critical roles in the patterning of brain and gut. The basal chordate, amphioxus, contains a single ParaHox cluster comprising one member of each family, whereas nonteleost jawed vertebrates contain four ParaHox genomic loci with six or seven ParaHox genes. Teleosts, which have experienced an additional whole-genome duplication, contain six ParaHox genomic loci with six ParaHox genes. Jawless vertebrates, represented by lampreys and hagfish, are the most ancient group of vertebrates and are crucial for understanding the origin and evolution of vertebrate gene families. We have previously shown that lampreys contain six Hox gene loci. Here we report that lampreys contain only two ParaHox gene clusters (designated as α- and β-clusters) bearing five ParaHox genes (Gsxα, Pdxα, Cdxα, Gsxβ, and Cdxβ). The order and orientation of the three genes in the α-cluster are identical to that of the single cluster in amphioxus. However, the orientation of Gsxβ in the β-cluster is inverted. Interestingly, Gsxβ is expressed in the eye, unlike its homologs in jawed vertebrates, which are expressed mainly in the brain. The lamprey Pdxα is expressed in the pancreas similar to jawed vertebrate Pdx genes, indicating that the pancreatic expression of Pdx was acquired before the divergence of jawless and jawed vertebrate lineages. It is likely that the lamprey Pdxα plays a crucial role in pancreas specification and insulin production similar to the Pdx of jawed vertebrates.
摘要译文
ParaHox基因（Gsx，Pdx和Cdx）是与Hox基因密切相关的发育基因的古老家族。他们在脑和肠的图案化方面发挥关键作用。基底脊索动物，amphioxus，包含一个单一ParaHox簇包含每个家庭的一个成员，而nonteleost下颌脊椎动物包含四个ParaHox基因座位点六个或七个ParaHox基因。硬骨鱼，其经历了额外的全基因组重复，包含六个ParaHox基因座基因座和六个ParaHox基因。无辜的脊椎动物，以灯塔和，鱼为代表，是最古老的脊椎动物群，对于了解脊椎动物基因家族的起源和进化至关重要。我们以前表明，lampreys含有六个Hox基因座。在这里我们报告说，lampreys只包含两个具有5个ParaHox基因（Gsxα，Pdxα，Cdxα，Gsxβ和Cdxβ）的ParaHox基因簇（称为α和β簇）。α簇中三个基因的顺序和方向与amphioxus中单个簇的序列和方向相同。然而，β-簇中Gsxβ的取向反转。有趣的是，Gsxβ在眼睛中表达，与其在主要在脑中表达的下颌脊椎动物中的同源物不同。阑尾Pdxα在胰腺中表达，与下颌脊椎动物Pdx基因相似，表明Pdx的胰腺表达在无颌和下颌的脊椎动物谱系发散之前获得。鲤鱼Pdxα很可能在胰腺规格和胰岛素生产中起着关键作用，类似于下颌脊椎动物的Pdx。
Huixian Zhang[a];[b];[1]; Vydianathan Ravi[a];[1]; Boon-Hui Tay[a]; Sumanty Tohari[a]; Nisha E. Pillai[a]; Aravind Prasad[a]; Qiang Lin[b]; Sydney Brenner[a];[2]; and Byrappa Venkatesh[a];[c];[2]. Lampreys, the jawless vertebrates, contain only two ParaHox gene clusters[J]. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2017,114(34): 9146-9151