Regulation of Olfactory Associative Memory by the Circadian Clock Output Signal Pigment-Dispersing Factor (PDF)

ABSTRACTDissociation between the output of the circadian clock and external environmental cues is a major cause of human cognitive dysfunction. While the effects of ablation of the molecular clock on memory have been studied in many systems, little has been done to test the role of specific clock circuit output signals. To address this gap, we examined the effects of mutation of Pigment-dispersing factor (Pdf) and its receptor, Pdfr on associative memory in male and female Drosophila. Loss of PDF signaling significantly decreases the ability to form associative memory. Appetitive short-term memory (STM), which in wildtype is time-of-day (TOD)-independent, is decreased across the day by mutation of Pdf or Pdfr, but more substantially in the morning than in the evening. This defect is due to PDFR expression in adult neurons outside the core clock circuit and the mushroom body Kenyon cells. The acquisition of a TOD difference in mutants implies the existence of multiple oscillators that act to normalize memory formation across the day for appetitive processes. Interestingly, aversive STM requires PDF but not PDFR, suggesting that there are valence-specific pathways downstream of PDF that regulate memory formation. These data argue that the circadian clock uses circuit-specific and molecularly diverse output pathways to enhance the ability of animals to optimize responses to changing conditions.SIGNIFICANCE STATEMENTFrom humans to invertebrates, cognitive processes are influenced by organisms’ internal circadian clocks, the pace of which is linked to the solar cycle. Disruption of this link is increasingly common (e.g. jetlag, social jetlag disorders) and causes cognitive impairments that are costly and long-lasting. A detailed understanding of how the internal clock regulates cognition is critical for the development of therapeutic methods. Here, we show for the first time that olfactory associative memory in Drosophila requires signaling by Pigment-dispersing factor (PDF), a neuromodulatory signaling peptide produced only by circadian clock circuit neurons. We also find a novel role for the clock circuit in stabilizing appetitive sucrose/odor memory across the day.

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Pigment Dispersing Factor: An Output Regulator of the Circadian Clock in the German Cockroach

Journal of Biological Rhythms ◽

10.1177/0748730408327909 ◽

2009 ◽

Vol 24 (1) ◽

pp. 35-43 ◽

Cited By ~ 30

Author(s):

Chi-Mei Lee ◽

Ming-Tsan Su ◽

How-Jing Lee

Keyword(s):

Circadian Clock ◽

German Cockroach ◽

Pigment Dispersing Factor

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Beyond spikes: Multiscale computational analysis of in vivo long-term recordings in the cockroach circadian clock

Network Neuroscience ◽

10.1162/netn_a_00106 ◽

2019 ◽

Vol 3 (4) ◽

pp. 944-968 ◽

Cited By ~ 3

Author(s):

Pablo Rojas ◽

Jenny A. Plath ◽

Julia Gestrich ◽

Bharath Ananthasubramaniam ◽

Martin E. Garcia ◽

...

Keyword(s):

Circadian Clock ◽

Field Potential ◽

Dynamic Features ◽

Pigment Dispersing Factor ◽

Gamma Frequency ◽

Accessory Medulla ◽

Electrophysiological Recordings ◽

Wide Range

The circadian clock of the nocturnal Madeira cockroach is located in the accessory medulla, a small nonretinotopic neuropil in the brain’s visual system. The clock comprises about 240 neurons that control rhythms in physiology and behavior such as sleep-wake cycles. The clock neurons contain an abundant number of partly colocalized neuropeptides, among them pigment-dispersing factor (PDF), the insects’ most important circadian coupling signal that controls sleep-wake rhythms. We performed long-term loose-patch clamp recordings under 12:12-hr light-dark cycles in the cockroach clock in vivo. A wide range of timescales, from milliseconds to seconds, were found in spike and field potential patterns. We developed a framework of wavelet transform–based methods to detect these multiscale electrical events. We analyzed frequencies and patterns of events with interesting dynamic features, such as mixed-mode oscillations reminiscent of sharp-wave ripples. Oscillations in the beta/gamma frequency range (20–40 Hz) were observed to rise at dawn, when PDF is released, peaking just before the onset of locomotor activity of the nocturnal cockroach. We expect that in vivo electrophysiological recordings combined with neuropeptide/antagonist applications and behavioral analysis will determine whether specific patterns of electrical activity recorded in the network of the cockroach circadian clock are causally related to neuropeptide-dependent control of behavior.

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The Paralogous Krüppel-like Factors 9 and 13 Regulate the Mammalian Cellular Circadian Clock Output Gene Dbp

Journal of Biological Rhythms ◽

10.1177/0748730420913205 ◽

2020 ◽

Vol 35 (3) ◽

pp. 257-274 ◽

Cited By ~ 2

Author(s):

Joseph R. Knoedler ◽

José Ávila-Mendoza ◽

Arasakumar Subramani ◽

Robert J. Denver

Keyword(s):

Circadian Clock ◽

Transcriptional Activation ◽

Mutational Analysis ◽

Direct Interaction ◽

Circadian Oscillation ◽

Ht22 Cells ◽

The Core ◽

Mouse Hippocampus ◽

E Boxes ◽

Circadian Clock Output

An intricate transcription-translation feedback loop (TTFL) governs cellular circadian rhythms in mammals. Here, we report that the zinc finger transcription factor Krüppel-like factor 9 (KLF9) is regulated by this TTFL, it associates in chromatin at the core circadian clock and clock-output genes, and it acts to modulate transcription of the clock-output gene Dbp. Our earlier genome-wide analysis of the mouse hippocampus-derived cell line HT22 showed that KLF9 associates in chromatin with Per1, Per3, Dbp, Tef, Bhlhe40, Bhlhe41, Nr1d1, and Nr1d2. Of the 3514 KLF9 peaks identified in HT22 cells, 1028 contain E-box sequences to which the transcriptional activators CLOCK and BMAL1 may bind, a frequency significantly greater than expected by chance. Klf9 mRNA showed circadian oscillation in synchronized HT22 cells, mouse hippocampus, and liver. At the clock-output gene Dbp, KLF9 exhibited circadian rhythmicity in its association in chromatin in HT22 cells and hippocampus. Forced expression of KLF9 in HT22 cells repressed basal Dbp transcription and strongly inhibited CLOCK+BMAL1-dependent transcriptional activation of a transfected Dbp reporter. Mutational analysis showed that this action of KLF9 depended on 2 intact KLF9-binding motifs within the Dbp locus that are in close proximity to E-boxes. Knockout of Klf9 or the paralogous gene Klf13 using CRISPR/Cas9 genome editing in HT22 cells had no effect on Dbp expression, but combined knockout of both genes strongly impaired circadian Dbp mRNA oscillation. Like KLF9, KLF13 also showed association in chromatin with clock- and clock-output genes, and forced expression of KLF13 inhibited the actions of CLOCK+BMAL1 on Dbp transcription. Our results suggest novel and partly overlapping roles for KLF9 and KLF13 in modulating cellular circadian clock output by a mechanism involving direct interaction with the core TTFL.

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