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Targeted disruption of the mPer3 gene: subtle effects on circadian clock function
1Laboratory of Developmental Chronobiology, MassGeneral Hospital for Children, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Molecular and Cellular Biology
|August 11, 2000
Summary
Mouse PER3 (mPER3) is not essential for circadian rhythms. Mice lacking mPER3 exhibited normal activity patterns, indicating its dispensability in the core circadian timing system.
Area of Science:
- Chronobiology
- Molecular Biology
- Genetics
Background:
- Mammalian circadian clocks, particularly in the suprachiasmatic nucleus (SCN), rely on transcriptional-translational feedback loops.
- Key components include CLOCK, BMAL1, CRY1/2, and PER1/2/3 proteins, which regulate gene expression rhythmically.
Purpose of the Study:
- To investigate the specific role of mouse PER3 (mPER3) in the mammalian circadian timing system.
- To determine if mPER3 is essential for maintaining circadian rhythms in mice.
Main Methods:
- Generation of mPER3-deficient mice via targeted gene disruption.
- Western blot analysis to confirm the absence of mPER3 protein.
- Analysis of circadian gene expression rhythms (mPer1, mPer2, mCry1, Bmal1) in the SCN and skeletal muscle.
- Assessment of locomotor activity rhythms and circadian cycle length in mutant mice.
Main Results:
- Absence of mPER3 protein confirmed in homozygous mice.
- Circadian rhythms of mPer1, mPer2, mCry1, and Bmal1 RNA in the SCN were unaffected by mPER3 deficiency.
- Skeletal muscle expression of mPer1 and mPer2 RNAs also showed no difference between mutant and wild-type mice.
- Locomotor activity rhythms were largely normal, though a slight shortening of the circadian cycle length (0.5 h) was observed in mPER3-deficient mice.
Conclusions:
- Mouse PER3 (mPER3) is not required for the fundamental operation of the circadian clock in mice.
- While not essential, mPER3 may have subtle influences on circadian cycle length.