TY  - JOUR
AU  - Szalóki, Nikoletta
AU  - Krieger, Jan Wolfgang
AU  - Komáromi, István
AU  - Tóth, Katalin
AU  - Vámosi, György
TI  - Evidence for Homodimerization of the c-Fos Transcription Factor in Live Cells Revealed by Fluorescence Microscopy and Computer Modeling.
JO  - Molecular and cellular biology
VL  - 35
IS  - 21
SN  - 1098-5549
CY  - Washington, DC
PB  - Soc.
M1  - DKFZ-2017-03617
SP  - 3785 - 3798
PY  - 2015
AB  - The c-Fos and c-Jun transcription factors, members of the activator protein 1 (AP-1) complex, form heterodimers and bind to DNA via a basic leucine zipper and regulate the cell cycle, apoptosis, differentiation, etc. Purified c-Jun leucine zipper fragments could also form stable homodimers, whereas c-Fos leucine zipper homodimers were found to be much less stable in earlier in vitro studies. The importance of c-Fos overexpression in tumors and the controversy in the literature concerning c-Fos homodimerization prompted us to investigate Fos homodimerization. Förster resonance energy transfer (FRET) and molecular brightness analysis of fluorescence correlation spectroscopy data from live HeLa cells transfected with fluorescent-protein-tagged c-Fos indicated that c-Fos formed homodimers. We developed a method to determine the absolute concentrations of transfected and endogenous c-Fos and c-Jun, which allowed us to determine dissociation constants of c-Fos homodimers (Kd = 6.7 ± 1.7 μM) and c-Fos-c-Jun heterodimers (on the order of 10 to 100 nM) from FRET titrations. Imaging fluorescence cross-correlation spectroscopy (SPIM-FCCS) and molecular dynamics modeling confirmed that c-Fos homodimers were stably associated and could bind to the chromatin. Our results establish c-Fos homodimers as a novel form of the AP-1 complex that may be an autonomous transcription factor in c-Fos-overexpressing tissues and could contribute to tumor development.
KW  - Chromatin (NLM Chemicals)
KW  - Proto-Oncogene Proteins c-fos (NLM Chemicals)
KW  - Proto-Oncogene Proteins c-jun (NLM Chemicals)
KW  - Transcription Factor AP-1 (NLM Chemicals)
KW  - DNA (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:26303532
C2  - pmc:PMC4589601
DO  - DOI:10.1128/MCB.00346-15
UR  - https://inrepo02.dkfz.de/record/127594
ER  -