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Mol Cell Biol. 2006 Jun;26(12):4758-68.

Induction of immunoglobulin heavy-chain transcription through the transcription factor Bright requires TFII-I.

Author information

1
Oklahoma Medical Research Foundation, Immunobiology and Cancer Research Program, 825 N. E. 13th Street, Oklahoma City, OK 73104, USA.

Abstract

Bright/ARID3a/Dril1, a member of the ARID family of transcription factors, is expressed in a highly regulated fashion in B lymphocytes, where it enhances immunoglobulin transcription three- to sixfold. Recent publications from our lab indicated that functional, but not kinase-inactive, Bruton's tyrosine kinase (Btk) is critical for Bright activity in an in vitro model system, yet Bright itself is not appreciably tyrosine phosphorylated. These data suggested that a third protein, and Btk substrate, must contribute to Bright-enhanced immunoglobulin transcription. The ubiquitously expressed transcription factor TFII-I was identified as a substrate for Btk several years ago. In this work, we show that TFII-I directly interacts with human Bright through amino acids in Bright's protein interaction domain and that specific tyrosine residues of TFII-I are essential for Bright-induced activity of an immunoglobulin reporter gene. Moreover, inhibition of TFII-I function in a B-cell line resulted in decreased heavy-chain transcript levels. These data suggest that Bright functions as a three-component protein complex in the immunoglobulin locus and tie together previous data indicating important roles for Btk and TFII-I in B lymphocytes.

PMID:
16738337
PMCID:
PMC1489113
DOI:
10.1128/MCB.02009-05
[Indexed for MEDLINE]
Free PMC Article

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