1: Eur J Biochem. 2000 Nov;267(21):6413-22. 

Domains of Brn-2 that mediate homodimerization and interaction with general and
melanocytic transcription factors.

Smit DJ, Smith AG, Parsons PG, Muscat GE, Sturm RA.

Centre for Molecular and Cellular Biology, University of Queensland, Brisbane,
Queensland, Australia.

The class III POU gene brn-2, encoding the Brn-2/N-Oct-3 transcription factor,
is widely expressed in the developing mammalian central nervous system. Brn-2
has also been found to regulate the melanocytic phenotype with N-Oct-3 DNA
binding activity elevated in malignant melanoma, however, its mode of action is
yet to be defined. The functional role of the Brn-2 transcription factor has
been investigated through the analysis of protein-protein interactions it forms
with a number of basal and melanocytic transcriptional regulatory proteins. In
vivo interactions were tested by gene-cotransfection using the mammalian
GAL4-Herpes Simplex viral protein 16 (VP16) two hybrid formation and direct
protein binding by in vitro glutathione S-transferase (GST)-pull down assay. The
Brn-2 protein was found to homodimerize in vivo with high affinity, using Brn-2
deletion constructs dimer complex formation was found to be dependent on the
presence of both the homeodomain and linker regions of the POU-domain. However,
the POU-homoedomain was dispensable for the formation of the dimerization
interface in one of the partner molecules but not both, when the POU-linker
region was removed the ability to interact was lost irrespective of the presence
of the homeodomain. Dimerization of Brn-2/N-Oct-3 was also found to occur in DNA
binding assays using melanoma cell line nuclear extracts and a recently reported
dimer target sequence probe, which may have significant consequences for gene
regulation in melanocytic tumours. Low affinity Brn-2 protein contacts have also
been found with the basal transcription complex, including TATA binding protein
(TBP) and the transcriptional coactivator p300, and with the Sox-10 and Pax-3
transcription factors that are known to play an important role in melanocyte
cell formation.

PMID: 11029584 [PubMed - indexed for MEDLINE]


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