Recruitment of the extracellular signal-regulated kinase/ribosomal S6 kinase signaling pathway to the NFATc4 transcription activation complex.
Integration of protein kinases into transcription activation complexes influences the magnitude of gene expression. The nuclear factor of activated T cells (NFAT) group of proteins are critical transcription factors that direct gene expression in immune and nonimmune cells. A balance of phosphotransferase activity is necessary for optimal NFAT activation. Activation of NFAT requires dephosphorylation by the calcium-mediated calcineurin phosphatase to promote NFAT nuclear accumulation, and the Ras-activated extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase, which targets NFAT partners, to potentiate transcription. Whether protein kinases operate on NFAT and contribute positively to transcription activation is not clear. Here, we coupled DNA affinity isolation with in-gel kinase assays to avidly pull down the activated NFAT and identify its associated protein kinases. We demonstrate that p90 ribosomal S6 kinase (RSK) is recruited to the NFAT-DNA transcription complex upon activation. The formation of RSK-NFATc4-DNA transcription complex is also apparent upon adipogenesis. Bound RSK phosphorylates Ser(676) and potentiates NFATc4 DNA binding by escalating NFAT-DNA association. Ser(676) is also targeted by the ERK MAP kinase, which interacts with NFAT at a distinct region than RSK. Thus, integration of the ERK/RSK signaling pathway provides a mechanism to modulate NFATc4 transcription activity.
Yang
Teddy T C
TT
Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
Xiong
Qiufang
Q
Graef
Isabella A
IA
Crabtree
Gerald R
GR
Chow
Chi-Wing
CW
D041721:3T3-L1 Cells; D000818:Animals; D019556:COS Cells; D019703:Calcineurin / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; C494010:NFATC4 protein, human; D009687:Nuclear Proteins; D014157:Transcription Factors; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D019703:Calcineurin