抄録
CD23 has roles in proliferation, antigen uptake
and presentation, and the generation of IgE.
Signals through IL-4R and CD40 stimulate transcription
of CD23 in B cells and are necessary for
immunoglobulin class switch (IgCS). The same
signals induce nuclear translocation of Ku, which
is also required for IgCS, in human resting B
cells, suggesting that these signaling pathways are
connected. We examined the regulation of CD23
gene, and located the minimal promoter at
-132+80 region. A pair of 188bp inverted repeats
inhibited its activity. The intronic region including
EBV responsive element (EBVRE) and the surrounding
sequence, required the gene specific
promoter to enhance the reporter gene activity.
Western blotting and FACS analysis using subclones
of DND39 B cells infected with recombinant
EBV, revealed that CD23 upregulation did not necessarily
correlate with EBNA 2 and LMP 1 expression.
Although the specific binding of Ku to
EBVRE was not demonstrated, dominant negative
Ku80 suppressed IL-4 + anti-CD40-driven CD23
expression. These results suggest that Ku is
involved in gene regulation as a signal transducer
and gene enhance. Detailed analysis of CD23
gene regulation would lead to a better understanding
of disorders such as allergy and lymphoproliferation.
