Light does not degrade the constitutively expressed BMAL1 protein in the mouse suprachiasmatic nucleus
von Gall, Charlotte ; Noton, Elizabeth ; Lee, Choogon ; Weaver, David R.
Citations
Authors
Noton, Elizabeth
Lee, Choogon
Weaver, David R.
Student Authors
Faculty Advisor
Academic Program
UMass Chan Affiliations
Document Type
Publication Date
Keywords
Actins
Animals
Antibody Specificity
Basic Helix-Loop-Helix Transcription Factors
CLOCK Proteins
Circadian Rhythm
Genes, fos
Genotype
Image Processing, Computer-Assisted
Immunoblotting
Immunohistochemistry
Light
Male
Mice
Mice, Inbred C3H
Perfusion
Precipitin Tests
Reverse Transcriptase Polymerase Chain Reaction
Suprachiasmatic Nucleus
Trans-Activators
Transcription Factors
Neuroscience and Neurobiology
Subject Area
Collections
Embargo Expiration Date
Link to Full Text
Abstract
Biological rhythms in mammals are driven by a central circadian clock located in the suprachiasmatic nucleus (SCN). At the molecular level the biological clock is based on the rhythmic expression of clock genes. Two basic helix-loop-helix (bHLH)/PAS-containing transcription factors, CLOCK and BMAL1 (MOP3), provide the basic drive to the system by activating transcription of negative regulators through E box enhancer elements. A critical feature of circadian timing is the ability of the clockwork to be entrained to the environmental light/dark cycle. The light-resetting mechanism of the mammalian circadian clock is poorly understood. Light-induced phase shifts are correlated with the induction of the clock genes mPer1 and mPer2 and a subsequent increase in mPER1 protein levels. It has previously been suggested that rapid degradation of BMAL1 protein in the rat SCN is part of the resetting mechanism of the central pacemaker. Our study shows that BMAL1 and CLOCK proteins are continuously expressed at high levels in the mouse SCN, supporting the hypothesis that rhythmic negative feedback plays the major role in rhythm generation in the mammalian pacemaker. Using both immunocytochemistry and immunoblot analysis, our studies demonstrate that BMAL1 protein in the mouse SCN is not affected by a phase-resetting light pulse. These results indicate that rapid degradation of BMAL1 protein is not a consistent feature of resetting mechanisms in rodents.
Source
Eur J Neurosci. 2003 Jul;18(1):125-33.