Gene duplication plays a major role in gene co-option: Studies into the evolution of the motilin/ghrelin family and their receptors |
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Authors: | Jing He Irwin M David YaPing Zhang |
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Institution: | HE Jing 1,Irwin M. DAVID 1,2 & ZHANG YaPing 1,3 1 State Key Laboratory of Genetic Resource and Evolution,Kunming Institute of Zoology,Chinese Academy of Sciences,Kunming 650223,China,2 Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre,University of Toronto,Toronto,M5S1A1,Canada,3 Laboratory for Conservation and Utilization of Bioresource,Yunnan University,Kunming 650091 |
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Abstract: | Extant genes can be modified, or ‘tinkered with’, to provide new roles or new characteristics of these genes. At the genetic
level, this often involves gene duplication and specialization of the resulting genes into particular functions. We investigate
how ligand-receptor partnerships evolve after gene duplication. While significant work has been conducted in this area, the
examination of additional models should help us better understand the proposed models and potentially reveal novel evolutionary
patterns and dynamics. We use bioinformatics, comparative genomics and phylogenetic analyses to show that preproghrelin and
prepromotilin descended from a common ancestor and that a gene duplication generated these two genes shortly after the divergence
of amphibians and amniotes. The evolutionary history of the receptor family differs from that of their cognate ligands. GPR39
diverges first, and an ancestral receptor gives rise to receptors classified as fish-specific clade A, GHSR and MLNR by successive gene duplications occurring before the divergence of tetrapods and ray-finned fish. The ghrelin/GHSR system
is maintained and functionally conserved from fish to mammals. Motilin-MLNR specificity must have arisen by ligand-receptor coevolution after the MLN hormone gene diverged from the GHRL gene in the amniote lineage. Conserved molecular machinery can give rise to new neuroendocrine response mechanisms by the
co-option of duplicated genes. Gene duplication is both parsimonious and creative in producing elements for evolutionary tinkering
and plays a major role in gene co-option, thus aiding the evolution of greater biological complexity. |
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Keywords: | ghrelin motilin gene family ligand receptor coevolution gene interaction |
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