期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 103, 期 24, 页码 9327-9332出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0603601103
关键词
circadian clock; Clock gene; entrainment; suprachiasmatic nucleus; Per genes
资金
- Howard Hughes Medical Institute Funding Source: Medline
- NIA NIH HHS [P01 AG11492] Funding Source: Medline
- NIDCD NIH HHS [T32 DC000015, T32 DC00015] Funding Source: Medline
- NIMH NIH HHS [U01 MH061915, U01 MH061915-04, P50 MH074924, P50 MH074924-01, U01 MH61915] Funding Source: Medline
- NINDS NIH HHS [T32 NS071040] Funding Source: Medline
The mouse Clock gene encodes a basic helix-loop-helix-PAS transcription factor, CLOCK, that acts in concert with BMAL1 to form the positive elements of the circadian clock mechanism in mammals. The original Clock mutant allele is a dominant negative (antimorphic) mutation that deletes exon 19 and causes an internal deletion of 51 aa in the C-terminal activation domain of the CLOCK protein. Here we report that heterozygous Clock/+ mice exhibit high-amplitude phase-resetting responses to 6-h light pulses (Type 0 resetting) as compared with wild-type mice that have low amplitude (Type 1) phase resetting. The magnitude and time course of acute light induction in the suprachiasmatic nuclei of the only known light-induced core clock genes, Per1 and Per2, are not affected by the Clock/+ mutation. However, the amplitude of the circadian rhythms of Per gene expression are significantly reduced in Clock homozygous and heterozygous mutants. Rhythms of PER2::LUCIFERASE expression in suprachiasmatic nuclei explant cultures also are reduced in amplitude in Clock heterozygotes. The phase-response curves to changes in culture medium are Type 0 in Clock heterozygotes, but Type 1 in wild types, similar to that seen for light in vivo. The increased efficacy of resetting stimuli and decreased PER expression amplitude can be explained in a unified manner by a model in which the Clock mutation reduces circadian pacemaker amplitude in the suprackiasmatic nuclei.
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