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Glycogen synthase kinase 3, circadian rhythms, and bipolar disorder: a molecular link in the therapeutic action of lithium.

Kaladchibachi SA, Doble B, Anthopoulos N, Woodgett JR, Manoukian AS - J Circadian Rhythms (2007)

Bottom Line: We sought to investigate the role of GSK3 in the mammalian clock mechanism, as a possible mediator of lithium's therapeutic effects.Furthermore, we demonstrate that pharmacological inhibition of GSK3 activity by kenpaullone, a known antagonist of GSK3 activity, as well as by lithium, a direct inhibitor of GSK3 and the most common treatment for BPD, induces a phase delay in mPer2 transcription that resembles the effect observed with GSK3 knockdown.These results confirm GSK3 as a plausible target of lithium action in BPD therapeutics, and suggest the circadian clock mechanism as a significant modulator of lithium's clinical benefits.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Signaling Biology, Ontario Cancer Institute, University Health Network, 610 University Avenue, Toronto, Ont. M5G 2M9, Canada. 96kaladc@uhnres.utoronto.ca

ABSTRACT

Background: Bipolar disorder (BPD) is a widespread condition characterized by recurring states of mania and depression. Lithium, a direct inhibitor of glycogen synthase kinase 3 (GSK3) activity, and a mainstay in BPD therapeutics, has been proposed to target GSK3 as a mechanism of mood stabilization. In addition to mood imbalances, patients with BPD often suffer from circadian disturbances. GSK3, an essential kinase with widespread roles in development, cell survival, and metabolism has been demonstrated to be an essential component of the Drosophila circadian clock. We sought to investigate the role of GSK3 in the mammalian clock mechanism, as a possible mediator of lithium's therapeutic effects.

Methods: GSK3 activity was decreased in mouse embryonic fibroblasts (MEFs) genetically and pharmacologically, and changes in the cyclical expression of core clock genes--mPer2 in particular--were examined.

Results: We demonstrate that genetic depletion of GSK3 in synchronized oscillating MEFs results in a significant delay in the periodicity of the endogenous clock mechanism, particularly in the cycling period of mPer2. Furthermore, we demonstrate that pharmacological inhibition of GSK3 activity by kenpaullone, a known antagonist of GSK3 activity, as well as by lithium, a direct inhibitor of GSK3 and the most common treatment for BPD, induces a phase delay in mPer2 transcription that resembles the effect observed with GSK3 knockdown.

Conclusion: These results confirm GSK3 as a plausible target of lithium action in BPD therapeutics, and suggest the circadian clock mechanism as a significant modulator of lithium's clinical benefits.

No MeSH data available.


Related in: MedlinePlus

Circadian oscillation profiles of clock genes in wild-type and GSK3β-/- MEFs. A, wild type and B, GSK3β-/- cells were synchronized, harvested, processed, and the gene products were amplified as described in the Materials and Methods. The resulting transcriptional profiles of murine GAPDH, mPer2, mCry1, RevErbα, and Bmal1 were analyzed by reverse-transcription PCR. The subjective time points (TP) of peak expression are designated in white above the corresponding bands for each transcript examined. Panel C is a graphical depiction of mPer2 transcriptional oscillation based on relative values derived from densitometric measurements of PCR-amplified DNA bands in panels A and B expressed as percentages of the highest recorded value in each respective data set.
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Figure 1: Circadian oscillation profiles of clock genes in wild-type and GSK3β-/- MEFs. A, wild type and B, GSK3β-/- cells were synchronized, harvested, processed, and the gene products were amplified as described in the Materials and Methods. The resulting transcriptional profiles of murine GAPDH, mPer2, mCry1, RevErbα, and Bmal1 were analyzed by reverse-transcription PCR. The subjective time points (TP) of peak expression are designated in white above the corresponding bands for each transcript examined. Panel C is a graphical depiction of mPer2 transcriptional oscillation based on relative values derived from densitometric measurements of PCR-amplified DNA bands in panels A and B expressed as percentages of the highest recorded value in each respective data set.

Mentions: Although the expression patterns of known core clock genes have been previously documented, the control phase relationships among selected clock components were established in wild-type MEFs for comparative purposes prior to the investigation of the effects of GSK3 deficiency on the clock mechanism. Following serum shock treatment, the oscillatory transcriptional expression profile of four clock genes – mPer2 (Period 2), mCry1 (Cryptochrome 1), Bmal1 and RevErbα, were examined by reverse transcription (RT)-PCR. The Clk (Clock) gene was excluded from this study as Clk mRNA and CLK protein are constitutively expressed [36]. The resulting expression profiles (Fig. 1A) and phase relationships of these four genes were consistent with previously published accounts [23,24,34,37,38].


Glycogen synthase kinase 3, circadian rhythms, and bipolar disorder: a molecular link in the therapeutic action of lithium.

Kaladchibachi SA, Doble B, Anthopoulos N, Woodgett JR, Manoukian AS - J Circadian Rhythms (2007)

Circadian oscillation profiles of clock genes in wild-type and GSK3β-/- MEFs. A, wild type and B, GSK3β-/- cells were synchronized, harvested, processed, and the gene products were amplified as described in the Materials and Methods. The resulting transcriptional profiles of murine GAPDH, mPer2, mCry1, RevErbα, and Bmal1 were analyzed by reverse-transcription PCR. The subjective time points (TP) of peak expression are designated in white above the corresponding bands for each transcript examined. Panel C is a graphical depiction of mPer2 transcriptional oscillation based on relative values derived from densitometric measurements of PCR-amplified DNA bands in panels A and B expressed as percentages of the highest recorded value in each respective data set.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1803776&req=5

Figure 1: Circadian oscillation profiles of clock genes in wild-type and GSK3β-/- MEFs. A, wild type and B, GSK3β-/- cells were synchronized, harvested, processed, and the gene products were amplified as described in the Materials and Methods. The resulting transcriptional profiles of murine GAPDH, mPer2, mCry1, RevErbα, and Bmal1 were analyzed by reverse-transcription PCR. The subjective time points (TP) of peak expression are designated in white above the corresponding bands for each transcript examined. Panel C is a graphical depiction of mPer2 transcriptional oscillation based on relative values derived from densitometric measurements of PCR-amplified DNA bands in panels A and B expressed as percentages of the highest recorded value in each respective data set.
Mentions: Although the expression patterns of known core clock genes have been previously documented, the control phase relationships among selected clock components were established in wild-type MEFs for comparative purposes prior to the investigation of the effects of GSK3 deficiency on the clock mechanism. Following serum shock treatment, the oscillatory transcriptional expression profile of four clock genes – mPer2 (Period 2), mCry1 (Cryptochrome 1), Bmal1 and RevErbα, were examined by reverse transcription (RT)-PCR. The Clk (Clock) gene was excluded from this study as Clk mRNA and CLK protein are constitutively expressed [36]. The resulting expression profiles (Fig. 1A) and phase relationships of these four genes were consistent with previously published accounts [23,24,34,37,38].

Bottom Line: We sought to investigate the role of GSK3 in the mammalian clock mechanism, as a possible mediator of lithium's therapeutic effects.Furthermore, we demonstrate that pharmacological inhibition of GSK3 activity by kenpaullone, a known antagonist of GSK3 activity, as well as by lithium, a direct inhibitor of GSK3 and the most common treatment for BPD, induces a phase delay in mPer2 transcription that resembles the effect observed with GSK3 knockdown.These results confirm GSK3 as a plausible target of lithium action in BPD therapeutics, and suggest the circadian clock mechanism as a significant modulator of lithium's clinical benefits.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Signaling Biology, Ontario Cancer Institute, University Health Network, 610 University Avenue, Toronto, Ont. M5G 2M9, Canada. 96kaladc@uhnres.utoronto.ca

ABSTRACT

Background: Bipolar disorder (BPD) is a widespread condition characterized by recurring states of mania and depression. Lithium, a direct inhibitor of glycogen synthase kinase 3 (GSK3) activity, and a mainstay in BPD therapeutics, has been proposed to target GSK3 as a mechanism of mood stabilization. In addition to mood imbalances, patients with BPD often suffer from circadian disturbances. GSK3, an essential kinase with widespread roles in development, cell survival, and metabolism has been demonstrated to be an essential component of the Drosophila circadian clock. We sought to investigate the role of GSK3 in the mammalian clock mechanism, as a possible mediator of lithium's therapeutic effects.

Methods: GSK3 activity was decreased in mouse embryonic fibroblasts (MEFs) genetically and pharmacologically, and changes in the cyclical expression of core clock genes--mPer2 in particular--were examined.

Results: We demonstrate that genetic depletion of GSK3 in synchronized oscillating MEFs results in a significant delay in the periodicity of the endogenous clock mechanism, particularly in the cycling period of mPer2. Furthermore, we demonstrate that pharmacological inhibition of GSK3 activity by kenpaullone, a known antagonist of GSK3 activity, as well as by lithium, a direct inhibitor of GSK3 and the most common treatment for BPD, induces a phase delay in mPer2 transcription that resembles the effect observed with GSK3 knockdown.

Conclusion: These results confirm GSK3 as a plausible target of lithium action in BPD therapeutics, and suggest the circadian clock mechanism as a significant modulator of lithium's clinical benefits.

No MeSH data available.


Related in: MedlinePlus