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MCB 186 CIRCADIAN BIOLOGY Biochemistry of the Circadian Clock Lecture #3 October 3, 2007 J. W. Hastings. MODELING INPUT to and OUTPUT from THE CLOCK.
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MCB 186CIRCADIAN BIOLOGYBiochemistry of the Circadian ClockLecture #3 October 3, 2007J. W. Hastings
THIS IS ONLY A MODELDIFFERENT SYSTEMS MAY DIFFER:bacteria, plants, algae, fungi, animalsand, IT MAY BE INCORRECTe.g., THERE MAY BE TWO CLOCKSor THREE or MORE
DIFFERENT OSCILLATORS CONTROL GLOW & FLASHING Internnal Desynchronization
THREE RHYTHMS SIMULTANEOUSLY: PHASE-JUMPS ROENNEBERG & MORSE 1993 Fls Agg Glo
CORE PACEMAKER OSCILLATOR • BIOCHEMICAL ELEMENTS of the CLOCK • AFFECTED by SIGNAL TRANSDUCTION • CLOCK GENES vs CLOCK CONTROLLED • CLOCK PROTEINS vs CLOCK CONTROLLED
INPUT PATHWAYSSIGNAL TRANSDUCTION • MANY FACTORS AFFECT THE CLOCK • EFFECTS on PHASE and PERIOD DISTINCT • BIOCHEMICAL PATHWAYS UNKNOWN
OUTPUT PATHWAYSHOW DOES the CLOCK TURN PROCESSES ON and OFF? • TRANSCRIPTION: NEW mRNA, then protein • TRANSLATION: REGULATE PROTEIN SYNTHEIS • POST TRANSLATIONAL e.g. PHOSPHORYLATION
LUCIFERASE PROTEIN EXHIBITS A CIRCADIAN RHYTHM in LL Johnson et al.1984 Science 223 Western Blot
WESTERN BLOTS LUCFERIN BINDING PROTEIN, LD & LL A CLOCK CONTROLLED GENE Morse et al., 1989 PNAS 86
GONYAULAX CELLS AT NIGHT (LEFT) AND DAY PHASES FLUORESCENCE OF LUCIFERIN IN SCINTILLONS
Morse et al., 1989 PNAS 86 LBP mRNA DOES NOT CYCLE in GonyaulaxLBP SYNTHESIS & ABUNDANCE are STRONGLY CIRCADIAN LBP mRNA LBP abundance LBP synthesis
SYNTHESIS of MANY PROTEINS is CIRCADIAN CONTROLLEDIn Vivo PULSE LABELING MILOS et al, 1989 MILOS ET AL, 1989 Naturwisenschaften 77
SYNTHESIS of PROTEINS in vitro is NOT CLOCK CONTROLLED MILOS ET AL, 1989 Naturwisenschaften 77
Markovic et al., 1996 J. Biol. Rhythms 11 PATTERNS of CLOCK-CONTROLLED PROTEIN SYNTHESIS in Gony p21 unknown p32 PCP p33 OEE1 p45 GAPDH p55 Rubisco II p75 Luciferin binding protein
ABUNDANCE vs SYNTHESIS • SYNTHESIS RATE of a PROTEIN MAY EXHIBIT PRONOUNCED RHYTHM while RHYTHM in the ABUNDANCE of PROTEIN does NOT • ABUNDANCE RHYTHM DEPENDS on STABILITY OF MOLECULE
GAPDH SYNTHESIS, ACTIVITY & ABUNDANCE RHYTHMSFagan, Morse & Hastings, 1999
HALF-LIFE of PROTEIN AFFECTS AMPLITUDE of ABUNDANCE RHYTHM 12 hr 2 days
IS THERE a CORE CIRCADIAN OSCILLATOR?If so, HOW do we IDENTIFY the CELLULAR-BIOCHEMICAL CLOCK COMPONENTS?SPECIFIC INHIBITORS or MUTANTS AFFECTING CIRCADIAN RHYTHMS
SPECIFIC INHIBITORS can REVEAL PATHWAYS of CLOCK BIOCHEMISTRYPROTEIN synthesis inhibitorsPulses cause phase shiftsPROTEIN phosphorylation inhibitors Chronically cause period changes
PULSES of ANISOMYCIN (protein synthesis inhibitor)CAUSE PHASE SHIFTS in Gonyaulax
SPECIFIC INHIBITORS can REVEAL PATHWAYS of CLOCK BIOCHEMISTRYPROTEIN synthesis inhibitorspulses cause phase shiftsPROTEIN phosphorylation inhibitors chronically cause period changesKINASES
NO AFTER-EFFECT of EXPOSURE to 6-DMAP COMOLLI and HASTINGS, 1995
SPECIFIC INHIBITORS can REVEAL PATHWAYS of CLOCK BIOCHEMISTRYPROTEIN synthesis inhibitorspulses cause phase shiftsPROTEIN phosphorylation inhibitors chronically cause period changesPROTEIN PHOSPHATASES
EFFECT of OKADAIC ACID (Protein phosphatase inhibitor) on CIRCADIAN BIOLUMINESCENCE RHYTHM
PRCs: LIGHT-INDUCED DELAY-PHASE SHIFTS IN an LL BACKGROUND ARE EVOKED BY CREATINE
IS THERE a CORE CIRCADIAN OSCILLATOR?If so, HOW do we IDENTIFY the CELLULAR-BIOCHEMICAL COMPONENTS?SPECIFIC INHIBITORS or MUTANTS AFFECTING CIRCADIAN RHYTHMS
DROSOPHILA PERIOD GENE CLOCK MUTANTS WILD TYPE per+ ARHYHMIC pero SHORT PERIOD perS LONG PERIOD perL Map location of gene Clone, sequence gene Measure mRNA Express encoded protein
A FEW CIRCADIAN CLOCK GENES 4) ARABIDOPSIS toc1 (TIMING OF CAB) lhy (LATE ELONG HYPOCOTYL) cca1 (CIRC CLOCK ASSOCIATED) 5) MOUSE clk (CLOCK) per1 (PERIOD) 6) HAMSTER tau (PERIOD) 1) DROSOPHILA per (PERIOD) tim (TIMELESS) 2) NEUROSPORA frq (FREQUENCY) prd (PERIOD) 3) CYANOBACTERIA kai (CYCLE IN JAPANESE)
POSTULATED PATHWAYS & COMPONENTS in the REGULATION of CLOCK GENE EXPRESSION TTO TRANSCRIPTION TRANSLATION OSCILLATOR
COMMON ELEMENTS IN THE DESIGN OF CORE CIRCADIAN OSCILLATORS DUNLAP, 1999