TY - JOUR
T1 - Timeless is an important mediator of Ck2 effects on circadian clock function in vivo
AU - Meissner, Rose Anne
AU - Kilman, Valerie L.
AU - Lin, Jui Ming
AU - Allada, Ravi
PY - 2008/9/24
Y1 - 2008/9/24
N2 - Circadian oscillations in clock components are central to generation of self-sustained 24-h periodicity. In the Drosophila molecular clock, accumulation, phosphorylation, and degradation of PERIOD (PER) and TIMELESS (TIM) proteins govern period length. Yet little is known about the kinases that phosphorylate TIM in vivo. It has been shown previously that the protein kinase CK2 phosphorylates TIM in vitro. Here, we identify a role for CK2 in TIM regulation in vivo. Induction of a dominant-negative CK2α, CK2αTik (Tik), increases TIM protein and tim transcript levels, reduces oscillation amplitude, and results in persistent cytoplasmic TIM localization. Exposure to light and subsequent TIM degradation results in an increase in the fraction of the transcriptional repressor PER that is nuclear and suppression of per and tim RNA levels. TIM protein, but not tim transcript, levels are elevated in Tik mutants in a per01 background. In contrast, Tik effects on PER are undetectable in a tim01 background, suggesting that TIM is required for CK2 effects on PER. To identify potential CK2 target sites, we assayed TIM phosphorylation rhythms in a deletion mutant that removes a conserved serine-rich domain and found that TIM protein does not show robust rhythmic changes in mobility by Western blotting, a hallmark of rhythmic phosphorylation. The period lengthening effects in Tik heterozygotes are reduced in a timUL mutant that disrupts a putative CK2 phosphorylation site. Together, these data indicate that TIM is an important mediator of CK2 effects on circadian rhythms.
AB - Circadian oscillations in clock components are central to generation of self-sustained 24-h periodicity. In the Drosophila molecular clock, accumulation, phosphorylation, and degradation of PERIOD (PER) and TIMELESS (TIM) proteins govern period length. Yet little is known about the kinases that phosphorylate TIM in vivo. It has been shown previously that the protein kinase CK2 phosphorylates TIM in vitro. Here, we identify a role for CK2 in TIM regulation in vivo. Induction of a dominant-negative CK2α, CK2αTik (Tik), increases TIM protein and tim transcript levels, reduces oscillation amplitude, and results in persistent cytoplasmic TIM localization. Exposure to light and subsequent TIM degradation results in an increase in the fraction of the transcriptional repressor PER that is nuclear and suppression of per and tim RNA levels. TIM protein, but not tim transcript, levels are elevated in Tik mutants in a per01 background. In contrast, Tik effects on PER are undetectable in a tim01 background, suggesting that TIM is required for CK2 effects on PER. To identify potential CK2 target sites, we assayed TIM phosphorylation rhythms in a deletion mutant that removes a conserved serine-rich domain and found that TIM protein does not show robust rhythmic changes in mobility by Western blotting, a hallmark of rhythmic phosphorylation. The period lengthening effects in Tik heterozygotes are reduced in a timUL mutant that disrupts a putative CK2 phosphorylation site. Together, these data indicate that TIM is an important mediator of CK2 effects on circadian rhythms.
KW - CK2
KW - Circadian
KW - Drosophila
KW - Period
KW - Phosphorylation
KW - Timeless
UR - http://www.scopus.com/inward/record.url?scp=55749090812&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=55749090812&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.0840-08.2008
DO - 10.1523/JNEUROSCI.0840-08.2008
M3 - Article
C2 - 18815259
AN - SCOPUS:55749090812
SN - 0270-6474
VL - 28
SP - 9732
EP - 9740
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 39
ER -