生物谷报道：昆明动物研究所遗传资源与进化国家重点实验室(筹)何静等研究了脊椎动物motilin/ghrelin荷尔蒙及其受体基因家族的进化历史，揭示了ghrelin/GHSR信号通路系统的保守性，以及新的motilin/MLNR信号通路系统的演化形成机制。由此他们提出了分子相互作用网络系统进化形成的一种模式：新功能关系形成之前，通常存在基因共享，即一种分子参与到多个过程、多种分子间相互作用。基因重复产生了新的组分，其中一个被征募与已经存在的分子形成新的分子间相互作用，从而分化形成新的网络关系；另一个则维持原有的网络关系，并产生了功能的专化。这项工作对于理解复杂的分子相互作用网络系统的形成机制提供了新的线索。该成果是在973项目和国家自然科学基金资助下取得的，于近期发表在国际著名刊物Molecular Biology and Evolution网络上(doi:10.1093/molbev/msm161)。（援引 昆明动物研究所）
原始出处:
MBE Advance Access published online on August 16, 2007
Molecular Biology and Evolution, doi:10.1093/molbev/msm161
Insights into the Evolution of the Motilin/Ghrelin-Associated Family and Their Receptors
Jing He1,2, David M. Irwin3 and Ya-ping Zhang1,4
1 State Key Laboratory of Cellular and Molecular Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
2 The Graduate School, Chinese Academy of Sciences, Beijing 100049, China
3 Departments of Laboratory Medicine and Pathobiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
4 Laboratory for Conservation and Utilization of Bioresource, Yunnan University, Kunming 650091, China
Corresponding author: Prof. Dr. Ya-Ping Zhang, Laboratory of Cellular and Molecular Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu Kunming, Yunnan, 650223 P. R China PHONE:(+86) 871-519 0761; FAX:(+86) 871-519 5430, E-mail: zhangyp1@263.net.cn or zhangyp@mail.kiz.ac.cn
Received for publication April 16, 2007. Revision received July 16, 2007. Accepted for publication July 21, 2007.
A hormone-receptor pair is usually thought of as a biological lock and key. Building a lock-and-key system seems to require at least the evolution of two traits to happen simultaneously, an event that appears highly unlikely. Thus it is not apparent how selection can drive the evolution of a part of the system as a whole. Here we demonstrate how evolutionary processes assemble complex systems that depend on specific interactions among the parts. Based on phylogenetic analyses and molecular inferences, we show that, MLN and GHRL descended from a common ancestor, and that gene duplication occurred shortly after the divergence of amphibians and amniotes. The evolutionary history of the receptors differs from their cognate ligands. GPR39 diverged first, and an ancestral GHSR-like receptor gave rise to a fish specific clade A, GHSR and MLNR by successive gene duplication that occurred before the divergence of tetrapods and fish. The ghrelin/GHSR system has been maintained and functionally conserved from fish to mammals, while motilin-MLNR specificity only evolved, as the result of ligand-receptor coevolution, after the hormone gene duplicated. A model for the evolution of novelties in tightly integrated biological systems is proposed under which a period of gene sharing ordinarily precedes the evolution of distinct functionality. Novel interactions emerge when a newly generated molecule is recruited as a binding partner of an old molecule, which was previously constrained by selection for a different function. Gene duplication then allows each daughter gene to specialize for subfunctions of the ancestral gene.
Key Words: ghrelin • motilin • obestatin • gene family • receptor • coevolution • gene interaction
