Evolution of interleukin-18 binding proteins and interleukin-1 receptor, type II proteins

  • Authors: Makoto Watanabe, Naohisa Goto, Yuko Watanabe, Seiji Nishiguchi, Kazunori Shimada, Teruo Yasunga, Hiromichi Yamanishi
  • View Affiliations

  • Published online on: Friday, April 1, 2005
  • Pages: 561-566
  • DOI: 10.3892/ijmm.15.4.561

Abstract

Interleukin-18 (IL-18) is one of the pivotal cytokines controlling the defense mechanism called inflammation. As a first step to develop proteins for controlling the IL-18 level, we initiated a study of IL-18-binding proteins (IL-18BPs). Twenty-four IL-18BP family members, 11 from vertebrates and 13 from chordopoxviruses, were picked from the NCBI database. Eight of these vertebrate IL-18BPs and two of the chordopoxvirus IL18-BPs were identified here and characterized as new members of the IL-18BP family. Their IL-18 binding domains were aligned and the distribution of highly conserved critical amino acid residues was analyzed and used to construct a phylogenetic tree. From this tree it was inferred that at least two independent events created two different ancestral viral IL-18BP genes by retroposition of IL-18BP genes from the vertebrate lineage. These two events are estimated to have occurred after an ancient mammalian IL-18BP gene diverged from birds, and before the mammalian IL-18BP gene diverged into human, ungulate and rodent IL-18BP genes. Moreover, our results suggest that IL-18BP and interleukin-1 receptor, type II (IL-1R2) had a common ancestral gene and diverged from the ancestral gene into IL-18BP and IL-1R2 genes in the fish period.
Journal Cover

April 2005
Volume 15 Issue 4

Print ISSN: 1107-3756
Online ISSN:1791-244X

2012 Impact Factor: 1.88
Ranked #27/122 Medicine Research and Experimental
(total number of cites)

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