Abstracts (complete list) - Wissenschaft Online

Andreas Brandl, Juergen Wittmann, Michael Boesl, Hans-Martin Jaeck
MicroRNA-Mediated Control of B Cell Activation
MicroRNAs (miRNAs) constitute a growing class of small noncoding RNAs that regulate
gene expression mainly at the posttranscriptional level. The regulatory function of
miRNAs has recently been shown to play critical roles in the control of hematopoiesis.
The goal of this project is to determine whether miRNAs function also during the
antigen-induced activation of B lymphocytes. To determine the miRNA profiles in naive
B cells before and after polyclonal activation, we stimulated B cells isolated via magnetic
CD43 beads from spleen with either LPS (simulates T cell-independent activation) or
with a combination of anti-IgM, anti-CD40 and IL4 (simulates T cell-dependent
activation) for various times. The analysis of isolated RNA using miRNA microarray- and
qRT-PCR assays identified about 104 miRNAs in unstimulated B cells. 35 of these were
mostly downregulated after stimulation. In silico analyses with various miRNA target
prediction programs revealed a very interesting and promising set of potential
transcripts whose translation/stability could be controlled by miRNAs during the antigeninduced
activation phase of mature B cells. Among these targets are BCR signalling
molecules and transcription factors that control proliferation, IgH class switch as well as
differentiation in antibody-secreting plasma cells. We will now verify biochemically
potential targets for each the differentially regulated miRNAs and determine the effect
of retrovirally transduced miRNAs on B cell development.