| Abstract |
ERF (ETS-2 Repressor factor) is a ubiquitously expressed protein, member of the ETS
family of transcription factors with strong transcriptional repressor activity. ERF is
regulated by MAPK/ERK signalling pathway. There are 2 FxF motifs on ERF that
mediate the specific interaction with ERKs, both in vivo and in vitro. The
phosphorylation determines its subcellular localization and biological function. Upon
mitogenic stimulation, ERF is phosphorylated and exported to the cytoplasm. In contrast,
upon growth factor deprivation ERF is immediately dephosphorylated and transported
into the nucleus.
Olig1 is a member of the oligodendrocyte lineage genes and encodes a bHLH protein
which is expressed in neural progenitor cells. It is strongly related with the
oligodendrocyte differentiation and maturation. Also involved in the mechanisms of
myelinogenesis of neurons, and overexpressed in all glial cancers.
Microarray experiment in primary MEFs carrying homozygous deletion of the ERF gene,
have shown overexpression of Olig1 gene. Chromatin IP experiments (CHIP) in primary
fibroblasts (MEFs) have shown that ERF binds to the Olig1 promoter with a higher
affinity in a 4 hours growth factor deprivation comparing with the exponential condition.
In vitro culturing E10,5 and E13,5 primary MEFs, have shown obvious differences in
Olig1 expression. In 4 hours serum deprivated E13,5 primary fibroblasts, the Olig1
expression have been decreased over the passages in the culture comparing with the
exponential condition. In contrast in the E10,5 primary MEFs at the same condition Olig1
expression was increased in progress of in vitro culturing.
Transfection experiments in REF1 cells have shown that ERF represses Olig1 gene.
Mutated form of ERF at all possible phoshorylation sites (M1-7) represses in much
higher degree compare with wild type ERF. At the same experiment in the presence of
trichostatin the repression seems to be maintained but in a smaller degree. In aim to map
the Olig1 promoter activity, we have been three different parts of the Olig1 promoter. We
observed that in all cases the ERF and M1-7 repression was maintained. We also
observed, that a very highly conserved region with the human Olig1 promoter, 145 bases
upstream the transcription start site, presents the same promoter activity as the entire
promoter. Mutation at the unique ETS sequence existing inside the conserved region with
the human Olig1 promoter, maintained the same precisely repression comparing with the
wild type promoter. This mutation only decreased the Olig1 promoter activity about 30-
50% roughly.
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Μελέτη της έκφρασης του Olig1 γονιδίου. Χαρτογράφηση του Olig1 υποκινητή και μελέτη της κατασταλτικής δράσης του ERF στο Olig1 γονίδιο
