In the article “Light Stimulates MSK1 Activation in the Suprachiasmatic Nucleus via a PACAP-ERK/MAP Kinase-Dependent Mechanism” by Greg Q. Butcher, Boyoung Lee, Hai-Ying Cheng, and Karl Obrietan, which appeared on pages 5305-5313 of the June 1, 2005 issue, inadvertent duplication of representative data in Figures 1 and 3 occurred. These errors were not incorporated into the statistical analysis, and thus the conclusions of the study were not affected. To mitigate this error, the authors have provided corrected versions of Figures 1 and 3 here. They would like to apologize to the readers of the Journal.
Light induces MSK1 phosphorylation. A, Mice were exposed to light during the subjective day (CT 6) or subjective night (CT 15 and CT 22). Representative images of SCN-containing coronal brain sections immunohistochemically labeled for pMSK1 are shown. Boxed regions are enlarged below each respective image. Box, 100 μm 2. 3V, Third ventricle; OC, optic chiasm. B, Mean number of pMSK1-positive cells per SCN section. Light exposure during the subjective day (CT 6) did not elicit pMSK1 (p > 0.1). Photic treatment at either night time point (CT 15 or CT 22) produced a significant increase in the number of cells containing pMSK1 relative to control animals killed at the same time points. Light treatment at CT 22 was also found to produce a significant increase in the number of pMSK1-positive cells compared with light exposure at CT 15. *p < 0.05. Numbers below each bar represent the number of animals used for each condition. C, RT-PCR analysis of MSK1 and CYCα mRNA expression in the SCN. D, Densitometric analysis of data presented in C revealed no significant variation in total MSK1 mRNA expression as a function of circadian time. Results are presented as the ratio of the MSK1 to cyclophilin. Data were averaged from triplicate determinations for each time point.
The MAPK and p38/MAPK pathways couple light to MSK1 activation. Cannulated animals were infused with 3 μl of DMSO (vehicle), U0126, SB203508, or a combination of U0126 and SB203508 45 min before light exposure (15 min, 100 lux) at CT 22. A, Representative coronal tissue sections immunolabeled for phosphorylated MSK1. Boxed regions are magnified below each image. B, Average number of pMSK1-positive cells per SCN. Disruption of the MAPK pathway significantly reduced the number of positive cells relative to DMSO infusion. SB203508 attenuated light-induced MSK1 activation; however, this effect failed to reach significance relative to DMSO infused, light-treated animals (p > 0.06). The combined administration of U0126 and SB203508 blocked MSK1 phosphorylation. *p < 0.001, relative to the DMSO-infused light-treated condition. Numbers below each bar represent the number of animals used for each condition.
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