Double-stranded RNA-mediated suppression of Period2 expression in the suprachiasmatic nucleus disrupts circadian locomotor activity in rats

Abstract

Circadian behavioral rhythms in mammals are controlled by a central clock located in the suprachiasmatic nucleus (SCN). PER2, the protein product of the clock gene, Period 2 (Per2), is expressed rhythmically in the SCN [Beaule C, Houle LM, Amir S (2003) Expression profiles of PER2 immunoreactivity within the shell and core regions of the rat suprachiasmatic nucleus: Lack of effect of photic entrainment and disruption by constant light. J Mol Neurosci 21:133-148] and has been implicated in the control of circadian behavioral rhythms based on the evidence that genetic mutations in Per2 abolish free running locomotor activity rhythms in mice [Zheng B, Larkin DW, Albrecht U, Sun ZS, Sage M, Eichele G, Lee CC, Bradley A (1999) The mPer2 gene encodes a functional component of the mammalian circadian clock. Nature 400:169-173; Bae K, Jin X, Maywood ES, Hastings MH, Reppert SM, Weaver DR (2001) Differential functions of mPer1, mPer2, and mPer3 in the SCN circadian clock. Neuron 30:525-536]. Such mutations eradicate PER2 expression in the SCN and disrupt the SCN molecular clockwork, however, they also affect PER2 in the rest of the brain and body leaving open the possibility that the changes in behavioral rhythms might be influenced, at least in part, by disruptions in PER2 functioning outside the SCN. We used RNA interference-mediated transient knockdown of Per2 to study the effect of selective suppression of PER2 expression in the SCN, per se, on behavioral circadian rhythms. We found that transient suppression of PER2 in the SCN disrupted free running locomotor activity rhythms for up to 10 days in rats. Infusions of control dsRNA into the SCN or infusions of dsRNA to Per2 immediately dorsal to the SCN had no effect. These results constitute evidence for a direct link between PER2 expression in the SCN and the expression of behavioral circadian rhythms in mammals.

The aging clock: circadian rhythms and later life

“…Further experiments within this study suggest that these changes in rhythmic PER2 expression in the SCN arise as a consequence of decreased rhythmic cell firing in the SCN (91). Targeted manipulation of clock genes selectively within the SCN yields changes in rhythms of physiology or behavior that approximate some of those observed during the natural course of aging (120). For example, a forebrain-specific deletion of floxed Bmal1 in mice profoundly affected locomotor activity rhythms and peripheral clock synchrony in the absence of a light/dark schedule, despite having no impact on lifespan (121).…”

Period2 gene mutant mice show compromised insulin-mediated endothelial nitric oxide release and altered glucose homeostasis

“…The mPer2 Brdm1 mutant mice were generated and propagated as previously described (Zheng et al, 1999). Briefly, mice were bred from pairs heterozygous for Per 2 Brdm 1 in mixed background of C57BL/6, 129SvEvBrd strains.…”

The APP-interacting protein FE65 is required for hippocampus-dependent learning and long-term potentiation

“…Before transfection or hippocampal infusion, the precipitate was washed by ice-cold 70% ethanol, dried, and resuspended in PBS at 10 mg/mL. For hippocampal infusion, 1 mL of double-stranded siRNA was mixed with 0.5 mL of Lipofectamine 2000 (Invitrogen) for 30 min at room temperature (Gavrila et al 2008). After deep anesthetization, the siRNA was delivered through a 30-gauge needle (1.5 mL for each side of the hippocampus at 0.15 mL/min) to the dorsal hippocampus.…”