title: Proteomic analysis reveals the role of synaptic vesicle cycling in sustaining the suprachiasmatic circadian clock.
abstract: The central circadian pacemaker of the suprachiasmatic nucleus (SCN) is characterized as a series of transcriptional/posttranslational feedback loops. How this molecular mechanism coordinates daily rhythms in the SCN and hence the organism is poorly understood. We conducted the first systematic exploration of the "circadian intracellular proteome" of the SCN and revealed that approximately 13% of soluble proteins are subject to circadian regulation. Many of these proteins have underlying nonrhythmic mRNAs, so they have not previously been noted as circadian. Circadian proteins of the SCN include rate-limiting factors in metabolism, protein trafficking, and, intriguingly, synaptic vesicle recycling. We investigated the role of this clock-regulated pathway by treating organotypic cultures of SCN with botulinum toxin A or dynasore to block exocytosis and endocytosis. These manipulations of synaptic vesicle recycling compromised circadian gene expression, both across the SCN as a circuit and within individual SCN neurons. These findings reveal how basic cellular processes within the SCN are subject to circadian regulation and how disruption of these processes interferes with SCN cellular pacemaking. Specifically, we highlight synaptic vesicle cycling as a novel point of clock cell regulation in mammals.
authors.affiliation: Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Deery
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Maywood
authors.forename: Johanna E
authors.initials: JE
authors.lastname: Chesham
authors.forename: Martin
authors.initials: M
authors.lastname: Sládek
authors.forename: Natasha A
authors.initials: NA
authors.lastname: Karp
authors.forename: Edward W
authors.initials: EW
authors.lastname: Green
authors.forename: Philip D
authors.initials: PD
authors.lastname: Charles
authors.forename: Akhilesh B
authors.initials: AB
authors.lastname: Reddy
authors.forename: Charalambos P
authors.initials: CP
authors.lastname: Kyriacou
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: Lilley
authors.forename: Michael H
authors.initials: MH
authors.lastname: Hastings
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D019274:Botulinum Toxins, Type A / Q000494:pharmacology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006835:Hydrazones / Q000494:pharmacology; D051379:Mice; D009498:Neurotoxins / Q000494:pharmacology; D040901:Proteomics; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000502:physiology*
chemical_list: D006835:Hydrazones; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D009498:Neurotoxins; D019274:Botulinum Toxins, Type A