Interacting regions in Stat3 and c-Jun that participate in cooperative transcriptional activation.
Independent but closely spaced DNA binding sites for Stat3 and c-Jun are required for maximal enhancer function in a number of genes, including the gene encoding the interleukin-6 (IL-6)-induced acute-phase response protein, alpha(2)-macroglobulin. In addition, a physical interaction of Stat3 with c-Jun, based on yeast two-hybrid interaction experiments, has been reported. Here we confirm the existence of an interaction between Stat3 and c-Jun both in vitro, with recombinant proteins, and in vivo, during transient transfection. Using fragments of both proteins, we mapped the interactive sites to the C-terminal region of c-Jun and to two regions in Stat3, within the coiled-coil domain and in a portion of the DNA binding domain distant from DNA contact sites. In transient-transfection experiments with the alpha(2)-macroglobulin enhancer, Stat3 and c-Jun cooperated to yield maximal enhancer function. Point mutations of Stat3 within the interacting domains blocked both physical interaction of Stat3 with c-Jun and their cooperation in IL-6-induced transcription directed by the alpha(2)-macroglobulin enhancer. While the amino acid sequences and the three-dimensional structures of Stat3 and Stat1 cores are very similar, fragments of Stat1 failed to bind c-Jun in vitro. Although Stat1 binds in vitro to the gamma interferon gene response (GAS) element in the alpha(2)-macroglobulin enhancer, Stat1 did not stimulate transcription, nor did Stat1 and c-Jun cooperate in driving transcription controlled by the alpha(2)-macroglobulin enhancer.
Zhang
X
X
Laboratory of Molecular Cell Biology, The Rockefeller University, New York, New York 10021, USA.
Wrzeszczynska
M H
MH
Horvath
C M
CM
Darnell
J E
JE
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D000511:alpha-Macroglobulins / Q000235:genetics
D004268:DNA-Binding Proteins; D015850:Interleukin-6; D016755:Proto-Oncogene Proteins c-jun; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D000511:alpha-Macroglobulins