Event Abstract

Evolution of the insulin-like growth factor binding protein (IGFBP) family in vertebrates

  • 1 Uppsala University, Department of Neuroscience, Sweden
  • 2 University of Michigan, Department of Molecular, United States

The IGFBPs are made from six distinct genes in placental mammals and several more in teleost fishes. Due to uneven rates of evolution in the different parts of the IGFBP proteins, it has been difficult to resolve their evolutionary history. Opposing views have favoured either block (chromosome) or serial duplications. We have combined sequence-based phylogenies with data on chromosomal locations in a large number of species and arrive at the following duplication scenario which is supported by the phylogenies of four adjacent gene families: An ancestral vertebrate IGFBP gene underwent a local gene duplication resulting in a gene pair. Subsequently, the two basal vertebrate tetraploidizations quadrupled this pair, after which one gene was lost from two of the pairs. This resulted in the six genes found in placental mammals. Teleost fishes have undergone a third tetraploidization that doubled the IGFBP repertoire to twelve members whereupon differential losses occurred in different lineages. The five sequenced teleost genomes retain 9-11 of the IGFBP genes. The aminoterminal domain is involved in IGF binding and has 12 perfectly conserved cysteines except in mammalian IGFBP-6, which has ten. Teleost fish IGFBP-6 has lost four additional cysteines, leaving only six, implying important structural differences. Interestingly, IGFBP-4 seems to have been lost independently in opossum and birds. The duplicates of IGFBP-1, 2 and 5 have been retained in all five sequenced teleost genomes suggesting important roles for these duplicates. The great ages for the IGFBP genes strongly suggest that they evolved distinct functions in early vertebrate evolution.

Keywords: comparative endocrinology

Conference: 25th Conference of the European Comparative Endocrinologists, Pécs, Hungary, 31 Aug - 4 Sep, 2010.

Presentation Type: Conference Presentation

Topic: Comparative endocrinology

Citation: Larhammar D, Sundström G, Bergqvist CA, Duan C and Ocampo Daza D (2010). Evolution of the insulin-like growth factor binding protein (IGFBP) family in vertebrates. Front. Endocrinol. Conference Abstract: 25th Conference of the European Comparative Endocrinologists. doi: 10.3389/conf.fendo.2010.01.00046

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Received: 26 Aug 2010; Published Online: 30 Aug 2010.

* Correspondence: Dr. Dan Larhammar, Uppsala University, Department of Neuroscience, Uppsala, Sweden, dan.larhammar@neuro.uu.se