HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by John, L. B. Articles by Ward, A. C. Search for Related Content PubMed PubMed Citation Articles by John, L. B. Articles by Ward, A. C. Pubmed/NCBI databases Gene GEO Profiles HomoloGene Protein UniGene Substance via MeSH

Evolution of the Ikaros Gene Family: Implications for the Origins of Adaptive Immunity ¹

Liza B. John^*,, Simon Yoong^* and Alister C. Ward^2,

^* Center for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia; and School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia

Members of the Ikaros family of transcription factors are important for immune system development. Analysis of Ikaros-related genes from a range of species suggests the Ikaros family derived from a primordial gene, possibly related to the present-day protostome Hunchback genes. This duplicated before the divergence of urochordates to produce two distinct lineages: one that generated the Ikaros factor-like (IFL) 2 genes of urochordates/lower vertebrates and the Pegasus genes of higher vertebrates, and one that generated the IFL1 genes of urochordates/lower vertebrates, the IKFL1 and IKFL2 genes of agnathans and the remaining four Ikaros members of higher vertebrates. Expansion of the IFL1 lineage most likely occurred via the two intervening rounds of whole genome duplication. A proposed third whole genome duplication in teleost fish produced a further increase in complexity of the gene family with additional Pegasus and Eos members. These findings question the use of IFL sequences as evidence for the existence of adaptive immunity in early chordates and vertebrates. Instead, this study is consistent with a later emergence of adaptive immunity coincident with the appearance of the definitive lymphoid markers Ikaros, Aiolos, and Helios.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ This project was supported by a Deakin Central Research Grant. L.B.J. received an Australian Postgraduate Award.

² Address correspondence and reprint requests to Prof. Alister C. Ward, School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia. E-mail address: award{at}deakin.edu.au

³ Abbreviations used in this paper: EST, expressed sequence tag; IFL/IKFL, Ikaros factor-like; ZF, zinc finger; ISH, in situ hybridization; BLAST, basic local alignment search tool.

⁴ The online version of this article contains supplemental material.