Regulation of Ig class switch recombination by @entity1991 : retroviral expression of @entity26336 in activated B cells inhibits switching to XXXX , but not to IgE.

@entity28348 @entity1992 @entity1991 @entity43329 @entity19 @entity9686 @entity58 @entity16181 @entity26336 @entity10986 @entity9749
Mutant @entity1991 -deficient B cells from knockout @entity19 lacking @entity1992 , @entity1991 / @entity1991 or the transactivation domain of @entity16181 exhibit distinct and selective cell-intrinsic defects in their ability to undergo class switch recombination ( @entity43329 ) to specific Ig isotypes. This isotype-specific requirement for particular @entity1991 transcription factors in B cells activated to undergo @entity43329 is intriguing because the @entity1991 composition in B cells is also highly regulated and can vary significantly depending upon how B cells are activated. These studies prompted us to test by retroviral transduction of normal B cells whether changes in the @entity1991 composition in activated B cells could modulate cytokine-driven @entity43329 . @entity26336 , @entity1992 , @entity16181 , @entity1991 and @entity28348 were first expressed in lipopolysaccharide-activated primary B cells and then induced by cytokine addition to undergo @entity43329 to @entity9686 , IgE, @entity9749 , @entity10986 or IgA. Surprisingly, only retroviral expression of @entity26336 altered @entity43329 , resulting in a 3-fold decrease in @entity43329 to @entity9686 induced by @entity58 . This effect was isotype specific as @entity26336 expression did not affect @entity43329 to IgE within the same culture or to other isotypes tested. The transactivation domain of @entity26336 was required for inhibition of @entity43329 to @entity9686 . Expression of @entity1991 - @entity26336 or @entity28348 - @entity26336 dimers joined covalently by a flexible peptide linker also specifically inhibited @entity9686 @entity43329 . @entity26336 -mediated inhibition of @entity9686 @entity43329 was associated with a decrease in germline gamma1 transcription, but not with changes in proliferation as assayed by CFSE labeling. Thus, @entity26336 complexes can specifically inhibit @entity43329 to @entity9686 , but not IgE, in activated, primary B cells.
