Abstracts (complete list) - Wissenschaft Online

Romney Haylett, Lothar Rink
MHC-II Signaling Directs the Activation of NFAT but not NF-κB
in B Cells
For over a decade major histocompatibility complex class II (MHC-II) molecules have
been acknowledged as signaling receptors although their mode of signaling and exact
signaling pathways have yet been fully clarified. In this study, the MAP kinase pathway
leading to ERK1/2 activation was explored for all three HLA isotypes (HLA-DR, -DP, -
DQ) in the B cell lines BJAB and Raji. Not only could ERK1/2 activity be observed after
signaling through all three isotypes, but the activation of c-Fos, a well-described
component of the AP-1 transcription factor known to be phosphorylated by ERK1/2, was
also established. This led to further studies pertaining to transcription factor activation
where ligation of MHC-II molecules ultimately led to NFAT1 activation but not NF-κB
activation in B cells. Future investigations should elucidate whether or not the entire AP-
1 complex interacts with NFAT in B cells after MHC-II ligation. Although NFAT1
activation has been described in B cells, relatively few work has been conducted in this
field. With the novel discovery of MHC-II molecules capable of inducing NFAT activation,
the understanding of MHC-II signaling and NFAT activation in B cells can be
tremendously greatened.