Okada Kinya, Asai Kiyoshi
Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
Gene. 2008 Apr 15;412(1-2):71-83. doi: 10.1016/j.gene.2008.01.016. Epub 2008 Jan 31.
The adenohypophysis of vertebrates receives peptide hormones from the hypothalamus and secretes hormones that regulate diverse physiologic processes in peripheral organs. The adenohypophysis-mediated endocrine system is widely conserved across vertebrates but not invertebrates. Phylogenetic analysis indicates that the emergence of this system coincided with two rounds of whole-genome duplication (2R-WGD) in early vertebrates, but direct evidence linking these events has been unavailable. We detected all human paralogons (series of paralogous regions) formed in early vertebrates as traces of 2R-WGD, and examined the relationship between 2R-WGD and the evolution of genes essential to the adenohypophysis-mediated endocrine system. Regarding genes encoding transcription factors (TFs) involved in the terminal differentiation into hormone-secreting cells in adenohypophyseal development, we showed that most pairs of these genes and their paralogs were part of paralogons. In addition, our analysis also indicated that most of the paralog pairs in families of adenohypophyseal hormones and their receptors were part of paralogons. These results suggest that 2R-WGD played an important role in generating genes encoding adenohypophyseal TFs, hormones, and their receptors for increasing the diversification of hormone repertoire in the adenohypophysis-mediated endocrine system of vertebrates.
脊椎动物的腺垂体接收来自下丘脑的肽类激素，并分泌调节外周器官多种生理过程的激素。腺垂体介导的内分泌系统在脊椎动物中广泛存在，但在无脊椎动物中则不存在。系统发育分析表明，该系统的出现与早期脊椎动物的两轮全基因组复制（2R-WGD）同时发生，但尚未有将这些事件联系起来的直接证据。我们检测了早期脊椎动物中形成的所有人类旁系同源区域（一系列同源区域），作为2R-WGD的痕迹，并研究了2R-WGD与腺垂体介导的内分泌系统所必需基因的进化之间的关系。关于在腺垂体发育中参与终末分化为激素分泌细胞的转录因子（TFs）编码基因，我们发现这些基因及其旁系同源基因的大多数对都是旁系同源区域的一部分。此外，我们的分析还表明，腺垂体激素及其受体家族中的大多数旁系同源基因对都是旁系同源区域的一部分。这些结果表明，2R-WGD在生成编码腺垂体TFs、激素及其受体的基因方面发挥了重要作用，从而增加了脊椎动物腺垂体介导的内分泌系统中激素库的多样性。
