A role for the segment polarity gene shaggy/GSK-3 in the Drosophila circadian clock.
Tissue-specific overexpression of the glycogen synthase kinase-3 (GSK-3) ortholog shaggy (sgg) shortens the period of the Drosophila circadian locomotor activity cycle. The short period phenotype was attributed to premature nuclear translocation of the PERIOD/TIMELESS heterodimer. Reducing SGG/GSK-3 activity lengthens period, demonstrating an intrinsic role for the kinase in circadian rhythmicity. Lowered sgg activity decreased TIMELESS phosphorylation, and it was found that GSK-3 beta specifically phosphorylates TIMELESS in vitro. Overexpression of sgg in vivo converts hypophosphorylated TIMELESS to a hyperphosphorylated protein whose electrophoretic mobility, and light and phosphatase sensitivity, are indistinguishable from the rhythmically produced hyperphosphorylated TIMELESS of wild-type flies. Our results indicate a role for SGG/GSK-3 in TIMELESS phosphorylation and in the regulated nuclear translocation of the PERIOD/TIMELESS heterodimer.
Martinek
S
S
Laboratory of Genetics and National Science Foundation Science and Technology Center for Biological Timing, The Rockefeller University, New York, NY 10021, USA.
Inonog
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Manoukian
A S
AS
Young
M W
MW
D021581:Active Transport, Cell Nucleus; D000818:Animals; D001683:Biological Clocks / Q000235:genetics / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D019281:Dimerization; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D038362:Glycogen Synthase Kinase 3; D015151:Immunoblotting; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009043:Motor Activity / Q000235:genetics / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism*; D056950:Period Circadian Proteins; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D029721:Drosophila Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; D011993:Recombinant Fusion Proteins; C096445:tim protein, Drosophila; D012313:RNA; D017346:Protein Serine-Threonine Kinases; C080335:Sgg protein, Drosophila; D038362:Glycogen Synthase Kinase 3