Moriyama Shunsuke, Oda Mayumi, Takahashi Akiyoshi, Sower Stacia A, Kawauchi Hiroshi
Laboratory of Molecular Endocrinology, School of Fisheries Sciences, Kitasato University, Sanriku, Iwate 022-0101, Japan.
Gen Comp Endocrinol. 2006 Aug;148(1):33-40. doi: 10.1016/j.ygcen.2005.09.023. Epub 2005 Nov 8.
Growth hormone (GH) belongs to a family of pituitary hormones together with prolactin and somatolactin. In our previous study, GH and its cDNA were identified in the pituitary gland of the sea lamprey, Petromyzon marinus, an extant representative of the most ancient class of vertebrates, and isolated GH stimulated expression of insulin-like growth factor in the liver. The evidence suggests that GH is the ancestral hormone in the molecular evolution of the GH/PRL/SL family and that the endocrine mechanism for growth stimulation was established at an early stage in the evolution of vertebrates. To further understand the molecular evolution of the GH/PRL/SL gene family, we report the genomic structure of sea lamprey GH including its 5'-flanking region, being cloned by PCR using specific primers prepared from its cDNA. The sea lamprey GH gene consists of 13,604 bp, making it the largest of all the GH genes. The 5'-flanking region within 697 bp contains consensus sequences for a TATA box, two Pit-1/GHF-1, three TRE, and a CRE. The sea lamprey GH gene consists of five exons and four introns, the same as in mammals, birds, and teleosts such as cypriniforms and siluriforms with the exception of some teleosts such as salmoniforms, percififorms, and tetradontiforms, in which there is an additional intron in the 5th exon. The 5-exon-type gene organization might reflect the structure of the ancestral gene for the GH/PRL/SL gene family.
生长激素（GH）与催乳素和生长抑素同属于垂体激素家族。在我们之前的研究中，在七鳃鳗（Petromyzon marinus）的垂体中鉴定出了生长激素及其cDNA，七鳃鳗是最古老的脊椎动物类群的现存代表，分离出的生长激素可刺激肝脏中胰岛素样生长因子的表达。有证据表明，生长激素是生长激素/催乳素/生长抑素（GH/PRL/SL）家族分子进化中的祖先激素，并且在脊椎动物进化的早期就建立了生长刺激的内分泌机制。为了进一步了解GH/PRL/SL基因家族的分子进化，我们报道了七鳃鳗生长激素的基因组结构，包括其5'侧翼区域，该区域是使用从其cDNA制备的特异性引物通过PCR克隆的。七鳃鳗生长激素基因由13604个碱基对组成，是所有生长激素基因中最大的。697个碱基对内的5'侧翼区域包含一个TATA盒、两个Pit-1/GHF-1、三个TRE和一个CRE的共有序列。七鳃鳗生长激素基因由五个外显子和四个内含子组成，这与哺乳动物、鸟类以及鲤形目和鲇形目等硬骨鱼相同，但鲑形目、鲈形目和鲀形目等一些硬骨鱼除外，在这些硬骨鱼的第5个外显子中有一个额外的内含子。5外显子型基因组织可能反映了GH/PRL/SL基因家族祖先基因的结构。
