Identification of heterogeneous nuclear ribonucleoprotein K (hnRNP K) as a repressor of C/EBPbeta-mediated gene activation.

Transcription factor C/EBPbeta has been known to regulate a wide array of genes including those involved in the acute-phase response. One of the molecular mechanisms underlying transcription activation by C/EBPbeta is through protein-protein interaction with other transcription factors. Here we report the identification and characterization of physical and functional interactions ...
between C/EBPbeta and heterogeneous nuclear ribonucleoprotein (hnRNP) K. This interaction results in the repression of C/EBPbeta-dependent trans-activation of the agp gene. Footprinting assays indicate that hnRNP K cannot bind to the promoter region of agp gene or interfere with the binding of C/EBPbeta to its cognate DNA site. Furthermore, agp gene activation by the synergistic interaction of Nopp140 and C/EBPbeta is abolished by hnRNP K. The kinetics of appearance of C/EBPbeta-hnRNP K complex in the nuclear extract after initiation of acute-phase reaction indicates that hnRNP K functions as a negative regulator of C/EBPbeta-mediated activation of agp gene.
Mesh Terms:
Amino Acid Sequence, Animals, CCAAT-Enhancer-Binding Proteins, Cell Line, Chromatography, Affinity, Cricetinae, DNA-Binding Proteins, Gene Expression Regulation, Heterogeneous-Nuclear Ribonucleoprotein K, Heterogeneous-Nuclear Ribonucleoproteins, Kinetics, Molecular Sequence Data, Nuclear Proteins, Rats, Repressor Proteins, Ribonucleoproteins, Transcriptional Activation
J. Biol. Chem.
Date: Apr. 24, 1998
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