Abstracts (poster) - Wissenschaft Online

Myriam Ekici, Mathias Hohl, Gerald Thiel
Transcription of genes encoding synaptic vesicle proteins in
human neural stem cells:chromatin accessability, histone
methylation pattern and essential role of REST
Human HNSC.100 neural stem cells differentiate into glia cells when the mitogens bFGF
and EGF are removed from the culture medium. This differentiation was blocked by
activation of a Raf1-estrogen receptor fusion protein, indicating that downregulation of
the ERK signaling pathway is required for gliogenesis. Incubation of the cells with
retinoic acid in the absence of mitogens induced neuronal differentiation that was
accompanied by an upregulation of neuronal gene expression, and a downregulation of
GFAP and nestin expression. Chromatin immunoprecipitation experiments revealed that
retinoic acid treatment changed the histone code of neuronal genes, encoding synapsin
I, synaptophysin and synaptotagmins II, IV and VII, from methylation of lysine residue 9
to methylation of lysine residue 4 of histone 3. Furthermore, binding of histone
deacetylase-1 as well as binding of the transcriptional repressor REST was reduced or
abolished following retinoic acid treatment, indicating that transcriptional repression of
neuronal genes via histone deacetylation was impaired. Accordingly, treatment of neural
stem cells with the histone deacteylase inhibitor trichostatin A induced expression of
synapsin I, synaptophysin, synaptobrevin 2 and synaptotagmins II, IV and VII.
Moreover, expression of a mutant of REST that contained a transcriptional activation
domain enhanced expression of synapsin I, synaptophysin, synaptobrevin 2 and
synaptotagmins II, IV and VII in undifferentiated neural stem cells. These data indicate
that these neuronal genes were accessible for the REST mutant in human neural stem
cells, although the genes were xembedded into a chromatin environment characterized
by the the epigenetic marker for silenced genes, H3metK9.
contact:
myriam ekici
university of saarland medical center
department of medical biochemistry and molecular biology
myriamekici@web.de
gebäude 44
66424 homburg (germany)