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Circadian Clocks

Clock Genes, Clock Cells and Clock Circuits: Circadian rhythms are an adaptation to the 24 hr day that we experience. Takahashi begins his talk with an historic overview of how the genes controlling circadian clocks were first identified in Drosophila and the cloning tour de force that was required to identify clock genes in mice. He also describes the experiments that resulted in the realization that all cells in the body have a circadian clock, not just cells in the brain.

Clock Genes, Clock Cells and Clock Circuits (cont.): Takahashi explains that the suprachiasmatic nucleus (SCN) in the brain generates a circadian rhythm of fluctuating body temperature that, in turn, signals to peripheral tissues. Heat shock factor 1 is one of the signaling molecules responsible for communicating the temperature information and resetting peripheral clocks.

Genetics of Mammalian Clocks: Takahashi describes how crossing many mice of different genetic backgrounds allowed his lab to identify several genes that impact the output of the clock gene system through different mechanisms.

Molecular Basis of a Clock: Takahashi begins the last part of his presentation with the crystal structures of BMAL1 and CLOCK, the two central activators of clock gene transcription. He goes on to describe how his lab showed that CLOCK:BMAL1 controls the DNA binding activity of transcriptional regulators of not only cycling genes, but also of basic cell functions such as RNA polymerase II occupancy and histone modifications.

Joseph Takahashi received his BA in biology from Swarthmore College, his PhD in neuroscience from the University of Oregon. He is a professor at University of Texas Southwestern Medical Center as well as an investigator at the Howard Hughes Medical Institute. (from ibiology.org)

1A. Clock Genes, Clock Cells and Clock Circuits
Takahashi begins his talk with an historic overview of how the genes controlling circadian clocks were first identified in Drosophila and the cloning tour de force that was required to identify clock genes in mice.

1B. Clock Genes, Clock Cells and Clock Circuits (cont.)
Takahashi explains that the suprachiasmatic nucleus (SCN) in the brain generates a circadian rhythm of fluctuating body temperature that, in turn, signals to peripheral tissues.

2. Genetics of Mammalian Clocks
Takahashi describes how crossing many mice of different genetic backgrounds allowed his lab to identify several genes that impact the output of the clock gene system through different mechanisms.

3. Molecular Basis of a Clock
Takahashi begins the last part of his presentation with the crystal structures of BMAL1 and CLOCK, the two central activators of clock gene transcription.