title: GSK-3 and CK2 Kinases Converge on Timeless to Regulate the Master Clock.
abstract: The molecular clock relies on a delayed negative feedback loop of transcriptional regulation to generate oscillating gene expression. Although the principal components of the clock are present in all circadian neurons, different neuronal clusters have varying effects on rhythmic behavior, suggesting that the clocks they house are differently regulated. Combining biochemical and genetic techniques in Drosophila, we identify a phosphorylation program native to the master pacemaker neurons that regulates the timing of nuclear accumulation of the Period/Timeless repressor complex. GSK-3/SGG binds and phosphorylates Period-bound Timeless, triggering a CK2-mediated phosphorylation cascade. Mutations that block the hierarchical phosphorylation of Timeless in vitro also delay nuclear accumulation in both tissue culture and in vivo and predictably change rhythmic behavior. This two-kinase phosphorylation cascade is anatomically restricted to the eight master pacemaker neurons, distinguishing the regulatory mechanism of the molecular clock within these neurons from the other clocks that cooperate to govern behavioral rhythmicity.
authors.affiliation: Laboratory of Genetics, The Rockefeller University, 1230 York Avenue, Box 288, New York, NY 10065, USA. Electronic address: dtop@rockefeller.edu.
authors.forename: Deniz
authors.initials: D
authors.lastname: Top
authors.affiliation: Laboratory of Genetics, The Rockefeller University, 1230 York Avenue, Box 288, New York, NY 10065, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Harms
authors.affiliation: Department of Physics, The University of Miami, 1320 Campo Sano Avenue, Coral Gables, FL 33146, USA.
authors.forename: Sheyum
authors.initials: S
authors.lastname: Syed
authors.affiliation: Laboratory of Genetics, The Rockefeller University, 1230 York Avenue, Box 288, New York, NY 10065, USA.
authors.forename: Eliza L
authors.initials: EL
authors.lastname: Adams
authors.affiliation: Laboratory of Genetics, The Rockefeller University, 1230 York Avenue, Box 288, New York, NY 10065, USA.
authors.forename: Lino
authors.initials: L
authors.lastname: Saez
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D057906:Circadian Clocks; D017124:Conserved Sequence; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology*; D038362:Glycogen Synthase Kinase 3 / Q000502:physiology*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational
chemical_list: D029721:Drosophila Proteins; C096445:tim protein, Drosophila; D047390:Casein Kinase II; D038362:Glycogen Synthase Kinase 3