Although transcriptional enhancers are essential for the expression of the immunoglobulin heavy chain (IgH) locus, they are also needed for the additional functions of V(D)J joining, V-region hypermutation and immunoglobulin (Ig) class switch recombination. This research is directed towards understanding the function of the enhancer that drives expression of the IgH locus in the channel catfish, a teleost fish and therefore lacking Ig class switching. Preliminary results suggest that the catfish IgH enhancer functions through a novel interaction of transcription factors bound to multiple interacting octamer and muE5 sites. The role of these sites in the function of the enhancer will be dissected by site-directed mutagenesis, and the function of the mutated enhancer will be assessed in transient expression assays upon transfection into catfish B-cells. Catfish muE5-binding factor(s) will be isolated and characterized. The interactions between Oct transcription factors, muE5binding factors and the DNA motifs that they recognize will be measured directly using the BiaCore 2000 instrument that utilizes surface plasmon resonance detection. Such studies will define whether or not cooperative binding reactions occur between the Oct and muE5-binding transcription factors. Gene expression driven by the interaction of octamer-binding (Oct) transcription factors with those binding to muE5 sites (typically bHLH or zinc-finger transcription factors) has not been reported in mammalian systems. Thus, these studies should shed light on novel' transcription factor interactions in Ig enhancers, and will also provide insight into how enhancer function has influenced the evolution of the IgH locus.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM062317-01
Application #
6228406
Study Section
Special Emphasis Panel (ZRG1-IMB (03))
Program Officer
Marino, Pamela
Project Start
2001-03-01
Project End
2005-02-28
Budget Start
2001-03-01
Budget End
2002-02-28
Support Year
1
Fiscal Year
2001
Total Cost
$238,453
Indirect Cost
Name
Medical University of South Carolina
Department
Biochemistry
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Richard, Mara L Lennard; Hikima, Jun-ichi; Wilson, Melanie R et al. (2009) BOB.1 of the channel catfish, Ictalurus punctatus: not a transcriptional coactivator? Mol Immunol 46:481-91
Hikima, Jun-Ichi; Lennard Richard, Mara L; Wilson, Melanie R et al. (2008) Interaction between E-protein and Oct transcription factors in the function of the catfish IGH enhancer. Dev Comp Immunol 32:1105-10
Hikima, Jun-ichi; Lennard Richard, Mara L; Wilson, Melanie R et al. (2008) Function of E-protein dimers expressed in catfish lymphocytes. Mol Immunol 45:1165-70
Lennard, Mara L; Hikima, Jun-ichi; Ross, David A et al. (2007) Characterization of an Oct1 orthologue in the channel catfish, Ictalurus punctatus: a negative regulator of immunoglobulin gene transcription? BMC Mol Biol 8:8
Hikima, Jun-Ichi; Lennard, Mara L; Wilson, Melanie R et al. (2006) Conservation and divergence of the Emicro3' enhancer in the IGH locus of teleosts. Immunogenetics 58:226-34
Bengten, E; Quiniou, S; Hikima, J et al. (2006) Structure of the catfish IGH locus: analysis of the region including the single functional IGHM gene. Immunogenetics 58:831-44
Cupit, Pauline M; Lennard, Mara L; Hikima, Jun-Ichi et al. (2006) Characterization of two POU transcription factor family members from the urochordate Oikopleura dioica. Gene 383:1-11
Bengten, Eva; Clem, L William; Miller, Norman W et al. (2006) Channel catfish immunoglobulins: repertoire and expression. Dev Comp Immunol 30:77-92
Hikima, Jun-Ichi; Lennard, Mara L; Wilson, Melanie R et al. (2006) Regulation of the immunoglobulin heavy chain locus expression at the phylogenetic level of a bony fish: transcription factor interaction with two variant octamer motifs. Gene 377:119-29
Lennard, Mara L; Wilson, Melanie R; Miller, Norman W et al. (2006) Oct2 transcription factors in fish--a comparative genomic analysis. Fish Shellfish Immunol 20:227-38

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