Unique function for carboxyl-terminal domain of Oct-2 in Ig-secreting cells.
The activity of Ig gene promoters and enhancers is regulated by two related transcription factors, Oct-1 (ubiquitous) and Oct-2 (B lineage specific), which bind the octamer motif (ATTTGCAT) present in these elements. As Ig promoter-binding factors, Oct-1 and Oct-2 each work together with a B lymphocyte-specific cofactor OCA-B/OBF-1/Bob-1 that interacts with them through their POU (DNA-binding) domains. Because both can mediate Ig promoter activity in B cells, there has been some question as to whether these two octamer-binding factors serve distinct functions in lymphocytes. We have shown previously that the silencing of B lymphocyte-specific genes in plasmacytoma x T lymphoma hybrids can be prevented by preserving Oct-2 expression. The pronounced effect of this transcription factor on the phenotype of plasmacytoma x T lymphoma hybrids established a critical role for Oct-2 not only in maintaining Ig gene expression, but in maintaining the overall genetic program of Ig-secreting cells. In the present study, we have explored the functional differences between Oct-1 and Oct-2 using chimeric Oct-1/Oct-2 proteins in cell fusion assays. Our results provide further evidence for an essential role for Oct-2 in Ig-secreting cells and identify the C-terminal domain of Oct-2 as responsible for its unique function in these cells.
Sharif
M N
MN
Department of Biological Sciences, Hunter College, Graduate School of City University of New York, New York, NY 10021, USA.
Radomska
H S
HS
Miller
D M
DM
Eckhardt
L A
LA
D000921:Antibody-Producing Cells / Q000378:metabolism*; D002459:Cell Fusion; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D020868:Gene Silencing; D005803:Genes, Immunoglobulin; D051863:Host Cell Factor C1; D006822:Hybrid Cells; D016399:Lymphoma, T-Cell / Q000235:genetics; D050811:Octamer Transcription Factor-1; D010446:Peptide Fragments; D010954:Plasmacytoma / Q000235:genetics; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D010446:Peptide Fragments; D014157:Transcription Factors