Mats L. Lundqvist (a)* Bryan R. McElveen (a) Darlene L. Middleton (a) Robert Chapman (b) and Gregory W. Warr (a)
Dev Comp Immunol. Author manuscript; available in PMC 2006 July 1. Published in final edited form as:
Dev Comp Immunol. 2006; 30(6): 575-587.
Published online 2005 June 20. doi: 10.1016/j.dci.2005.05.004.
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Immunoglobulin class switching is characteristic to the tetrapod lineage, but the nature of this process has been elucidated only in mammals, where I-exon transcription initiates and directs the recombination in the IgH locus. Here, it is shown that an Iexon occurs 5' of the ? (IgY constant region) gene of the duck (Anas platyrhynchos): it is longer than mammalian I-exons and comprised primarily of tandem repeats. The I? promoter was identified and shown to be responsive to stimulation with IL-4 but not LPS. It contains Oct, LYF-1, ATF, and C/EBP motifs. Site directed mutagenesis indicates that 2 C/EBP motifs are uniquely necessary for the response of the promoter to IL-4, as tested in the mouse pre-B cell line, 70Z/3. These results support the conclusion that the signal transduction pathways controlling I-exon promoter responses to cytokines have been highly conserved in vertebrate evolution.
(a) Marine Biomedicine and Environmental Sciences Center and Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 331 Fort Johnson Road, Charleston, SC 29412, USA
(b) South Carolina Department of Natural Resources, Marine Resources Research Institute, Charleston SC 29412, USA
* Corresponding author.
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Hollings Marine Laboratory,
331 Fort Johnson Road, Charleston, SC, 29412 USA.
Tel.: +1 843 762 8803; fax: +1 843 762 8737.
E-mail address:firstname.lastname@example.org (M.L. Lundqvist). The publisher's final edited version of this article is available at Dev Comp Immunol