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Mol. Cell. Biol., 06 1997, 3335-3344, Vol 17, No. 6
K Merrell, S Wells, A Henderson, J Gorman, F Alt, A Stall and K Calame
TFE3 is a ubiquitously expressed member of the TFE3/mi family of basic
helix loop helix zipper transcription factors. TFE3 binds to muE3 sites
located in the immunoglobulin heavy-chain (IgH) intronic enhancer,
heavy-chain variable region promoters, the Ig kappa intronic enhancer, and
regulatory sites in other genes. To understand the role of TFE3 in Ig
expression and lymphoid development, we used embryonic stem (ES)
cell-mediated gene targeting and RAG2-/- blastocyst complementation to
generate mice which lack TFE3 in their B and T lymphocytes. TFE3- ES cells
fully reconstitute the B- and T-cell compartments, giving rise to normal
patterns of IgM+ B220+ B cells and CD4+ and CD8+ T cells. However, TFE3- B
cells show several defects consistent with poor B-cell activation. Serum
IgM levels are reduced twofold and IgG and IgA isotypes are reduced three-
to sixfold in the TFE3- chimeras even though in vitro, the TFE3-
splenocytes secrete normal levels of all isotypes in response to
lipopolysaccharide activation. Peripheral TFE3- B cells also show reduced
surface expression of CD23 and CD24 (heat- stable antigen).
Copyright © 1997, American Society for Microbiology
The absence of the transcription activator TFE3 impairs activation of B cells in vivo
Integrated Program in Cellular, Molecular and Biophysical Studies, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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