Regulation of immunoglobulin gene transcription in a teleost fish: identification, expression and functional properties of E2A in the channel catfish.
The function of the transcriptional enhancer, Emu3', of the IgH locus of the channel catfish, Ictalurus punctatus, involves the interaction of E-protein and Oct family transcription factors. The E-proteins [class I basic helix-loop-helix (bHLH) family] are encoded in mammals by three genes: E2A (of which E12/E47 are alternatively spliced products), HEB, and E2-2. An E2A homologue has been identified in a catfish B-cell cDNA library and contains regions homologous to the bHLH and activation domains of mammalian and other vertebrate E2A proteins. E2A message is widely expressed, being readily detected in catfish B cells, T cells, kidney, spleen, brain, and muscle. Its expression is lower than that previously observed for TF12/CFEB, the catfish homologue of HEB. E2A strongly activated transcription of a muE5 motif-dependent construct in catfish B cells, and also activated transcription from the core region of the catfish IgH enhancer (Emu3') in a manner dependent on the presence of the muE5 site. Catfish E2A, expressed in vitro, bound the muE5 motif present in the core region of Emu3'. These results document the conservation of structure and function in vertebrate E2A and suggest a potential role of E2A in driving expression of the IgH locus at the phylogenetic level of a teleost fish.
Hikima
Jun-ichi
J
Marine Biomedicine and Environmental Sciences Center, Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 331 Fort Johnson Road, Charleston, SC 29412, USA.
Middleton
Darlene L
DL
Wilson
Melanie R
MR
Miller
Norman W
NW
Clem
L William
LW
Warr
Gregory W
GW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004742:Enhancer Elements, Genetic; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005803:Genes, Immunoglobulin; D007059:Ictaluridae / Q000235:genetics* / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation
D018076:DNA, Complementary; D029941:Fish Proteins; D014157:Transcription Factors