Mitogen-activated protein kinase phosphorylates and negatively regulates basic helix-loop-helix-PAS transcription factor BMAL1.
In vertebrates, mitogen-activated protein kinase (MAPK) exhibits circadian activation in several clock structures and likely participates in the timekeeping mechanism of the circadian clock. Here we show that MAPK associates with a basic helix-loop-helix-PAS transcription factor BMAL1, a positive regulator for the autoregulatory feedback loop of the circadian oscillator. MAPK phosphorylates BMAL1 at multiple sites, including Ser-527, Thr-534, and Ser-599, in vitro, and BMAL1:CLOCK-induced transactivation from the E-box element is inhibited by expression of a constitutive active form of MAPK kinase in 293 cells. The inhibitory effect is reversed by coexpression of the kinase-dead mutant of MAPK or by mutation of BMAL1 at Thr-534. These results indicate that BMAL1:CLOCK-induced transcription is negatively regulated by MAPK-mediated phosphorylation of BMAL1 at Thr-534 and suggest a molecular link between circadian-activated MAPK and the clock oscillator.
Sanada
Kamon
K
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo and Core Research for Engineering, Science, and Technology, Japan Science and Technology, Tokyo 113-0033, Japan.
Okano
Toshiyuki
T
Fukada
Yoshitaka
Y
D056930:ARNTL Transcription Factors; D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D018257:Helix-Loop-Helix Motifs; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D015534:Trans-Activators / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D020928:Mitogen-Activated Protein Kinases; D015534:Trans-Activators; D014157:Transcription Factors