MAPK modulates the DNA binding of adipocyte enhancer-binding protein 1.
Adipocyte enhancer-binding protein 1 (AEBP1) is a down-regulator of adipogenesis through its transcriptional repression activity, as well as through its interaction with mitogen-activated protein kinase (MAPK), which protects MAPK from its specific phosphatases. This study increases our understanding of the mechanisms of DNA binding by AEBP1, the first step in its function as a transcriptional repressor. We show that DNA binding by AEBP1 requires both the N- and C-terminal domains of AEBP1, and MAPK interaction with AEBP1 (through its N terminus) results in enhanced DNA binding. A threonine at position 623 within the C-terminal domain of AEBP1 plays an important role in DNA binding by AEBP1, because the mutation results in decreased DNA binding by AEBP1, which leads to a decrease in the transcriptional repression ability of AEBP1. We also show that in vitro phosphorylation of AEBP1 by MAPK is greatly reduced upon mutation of T623. These results suggest that MAPK regulates the transcriptional activity of AEBP1 by a novel dual mechanism, in which MAPK interaction enhances and subsequent phosphorylation decreases the DNA-binding ability of AEBP1.
Lyons
Peter J
PJ
Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
Muise
Aleixo M
AM
Ro
Hyo-Sung
HS
D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases; D004247:DNA / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid
C484818:AEBP1 protein, human; D011506:Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D004247:DNA; D020928:Mitogen-Activated Protein Kinases; D002268:Carboxypeptidases