Circadian rhythms

  • Article
    | Open Access

    Tissue circadian clocks contribute to the regulation of physiology and metabolism. Here the authors investigate the role of the intestinal circadian clock in energy homeostasis and show that the intestinal clock acts as an accelerator in dietary fat absorption.

    • Fangjun Yu
    • , Zhigang Wang
    •  & Baojian Wu
  • Article
    | Open Access

    Alteration of circadian rhythms is often observed in patients with chronic kidney disease (CKD). Here, the authors show that CKD-induced dysfunction of the circadian clock increases the expression of G protein-coupled receptor 68 in circulating monocytes and that their cardiac infiltration exacerbates inflammation and fibrosis of heart.

    • Yuya Yoshida
    • , Naoya Matsunaga
    •  & Shigehiro Ohdo
  • Article
    | Open Access

    Whether chronic inflammation contributes to metabolic disease through the dysregulation of circadian systems remains incompletely understood in humans. Here the authors show that circadian clock function is perturbed in adipose tissue from individuals with obesity, and that inhibition of NFkB improves clock function.

    • Eleonore Maury
    • , Benoit Navez
    •  & Sonia M. Brichard
  • Article
    | Open Access

    Protein ubiquitylation is often studied by proteomics but how data independent acquisition (DIA) may advance these studies remains to be explored. Here, the authors show that DIA improves ubiquitylation site identification and quantification, enabling them to characterize the circadian ubiquitinome in human cells.

    • Fynn M. Hansen
    • , Maria C. Tanzer
    •  & Matthias Mann
  • Article
    | Open Access

    Circadian disruption is implicated in the development of different human cancers. Here the authors show that chronic circadian disruption, through continuous jet lag, only moderately affects primary tumour growth but promotes cancer-cell dissemination and metastasis in a mouse model of spontaneous mammary tumorigenesis.

    • Eva Hadadi
    • , William Taylor
    •  & Hervé Acloque
  • Article
    | Open Access

    Proteins KaiA, KaiB and KaiC constitute a biochemical circadian oscillator in Synechococcus cyanobacteria. Here, Kawamoto et al. show that kaiBC promoter activity exhibits a damped, low-amplitude circadian oscillation in the absence of KaiA, which could explain the circadian rhythms observed in other bacteria that lack a kaiA homologue.

    • Naohiro Kawamoto
    • , Hiroshi Ito
    •  & Hideo Iwasaki
  • Article
    | Open Access

    Disruption of different components of molecular circadian clocks has varying effects on health and lifespan of model organisms. Here the authors show that loss of period extends life in drosophila melanogaster.

    • Matt Ulgherait
    • , Anna Chen
    •  & Mimi Shirasu-Hiza
  • Article
    | Open Access

    Circadian rhythms can alter inflammatory state and activity of inflammatory diseases such as rheumatoid arthritis. Here the authors show that extrinsic signals confer a circadian rhythm to regulatory T cell activity, which in turn drives rhythmic inflammation in collagen-induced arthritis.

    • L. E. Hand
    • , K. J. Gray
    •  & J. E. Gibbs
  • Article
    | Open Access

    The cyanobacterium Synechococcus elongatus is a model organism for the study of circadian rhythms, and is naturally competent for transformation. Here, Taton et al. identify genes required for natural transformation in this organism, and show that the coincidence of circadian dusk and darkness regulates the competence state in different day lengths.

    • Arnaud Taton
    • , Christian Erikson
    •  & Susan S. Golden
  • Article
    | Open Access

    Circadian clocks control daily rhythms of molecular and physiological activities. Here, the authors show that the interaction between proteins FRQ and CK1, rather than FRQ stability, is a major rate-limiting step in circadian period determination in the model fungus Neurospora.

    • Xiao Liu
    • , Ahai Chen
    •  & Yi Liu
  • Article
    | Open Access

    The circadian clock affects immune responses, but its role in influenza infection is not well understood. Here, Sengupta et al. show that time of infection and the circadian clock have no effect on lung virus titers, but affect inflammation, morbidity and mortality.

    • Shaon Sengupta
    • , Soon Y. Tang
    •  & Garret A. FitzGerald
  • Article
    | Open Access

    Time-restricted feeding (TRF) has beneficial metabolic effects. Here the authors examine how TRF impacts muscle physiology using fly models of metabolically adverse conditions, including diet and genetic models of obesity as well as circadian rhythm disruption, and find that TRF ameliorates skeletal muscle dysfunction.

    • Jesús E. Villanueva
    • , Christopher Livelo
    •  & Girish C. Melkani
  • Article
    | Open Access

    The circadian transcription factors BMAL1:CLOCK bind to E/E′-boxes in gene regulatory elements of their targets and facilitate rhythmic expression. Here, the authors mutate the Per2 promoter E’′-box in mice and observe that cell- and tissue-autonomous oscillations are dampened and that animals are less susceptible to jet lag.

    • Masao Doi
    • , Hiroyuki Shimatani
    •  & Hitoshi Okamura
  • Perspective
    | Open Access

    Biological circadian rhythms maintain a period close to 24 h in coordination with the Earth’s fixed rotational period. Here Webb et al. discuss how external cues continuously adjust phase and period, viewing the oscillator as a dynamically-adjusted plastic system rather than tightly-coupled cogs in a mechanical clock.

    • Alex A. R. Webb
    • , Motohide Seki
    •  & Camila Caldana
  • Article
    | Open Access

    The circadian clock can affect pathogen replication, but underlying molecular mechanisms are unclear. Here the authors demonstrate that the circadian components BMAL1 and REV-ERBα affect entry of hepatitis C virus (HCV) into hepatocytes and genome replication of HCV and related flaviviruses dengue and zika.

    • Xiaodong Zhuang
    • , Andrea Magri
    •  & Jane A. McKeating
  • Article
    | Open Access

    Hepatocyte nuclear factor 4 alpha (HNF4α) is regulated by different promoters to generate two isoforms, one of which functions as a tumor suppressor. Here, the authors reveal that induction of the alternative isoform in hepatocellular carcinoma inhibits the circadian clock by repressing BMAL1, and the reintroduction of BMAL1 prevents HCC tumor growth.

    • Baharan Fekry
    • , Aleix Ribas-Latre
    •  & Kristin Eckel-Mahan
  • Article
    | Open Access

    Circadian clock regulates hepatic gene expression and functions. Here Chao et al. show that alteration of circadian clock genes by Period deletion induces polyploidy in hepatocytes due to impaired regulation of Erk signaling by mitogen-activated protein kinase phosphatase 1.

    • Hsu-Wen Chao
    • , Masao Doi
    •  & Hitoshi Okamura
  • Article
    | Open Access

    Circadian rhythms usually rely on cyclic variations in gene expression. Red blood cells, however, display circadian rhythms while being devoid of nuclear DNA. Here, Henslee and colleagues show that circadian rhythms in isolated human red blood cells are dependent on rhythmic transport of K+ ions.

    • Erin A. Henslee
    • , Priya Crosby
    •  & Fatima H. Labeed
  • Article
    | Open Access

    The misalignment between internal circadian rhythm and the day-night cycle can be caused by genetic, behavioural and environmental factors, and may have a profound impact on human physiology. Here West et al. show that desynchrony between the internal clock and the external environment alter metabolic parameters and cardiac function in mice.

    • Alexander C. West
    • , Laura Smith
    •  & David A. Bechtold
  • Article
    | Open Access

    Core clock genes, such asBmal1, are expressed in astrocytes, but their contribution to the timekeeping system is unknown. Barca-Mayo et al. report that deletion of Bmal1in Glast+ astrocytes alters the neuronal clock through GABA signalling, leading to abnormal circadian locomotor behaviour and impaired cognition in mice.

    • Olga Barca-Mayo
    • , Meritxell Pons-Espinal
    •  & Davide De Pietri Tonelli
  • Article
    | Open Access

    Circadian clocks regulate physiological and behavioural rhythms. Here, the authors show that the stiffness of the extracellular environment regulates circadian clocks in murine breast epithelium via Rho signalling, and explain how extracellular matrix stiffening in aging affects circadian rhythm, with implication in disease.

    • Nan Yang
    • , Jack Williams
    •  & Qing-Jun Meng
  • Article
    | Open Access

    TheArabidopsisCCA1 transcription factor is a core regulator of the circadian clock. Here, the authors show that the LWD1 protein, in complex with the TCP20 or TCP22 transcription factors, acts as a co-activator of CCA1 expression contributing to elevated CCA1 expression at dawn.

    • Jing-Fen Wu
    • , Huang-Lung Tsai
    •  & Shu-Hsing Wu
  • Article
    | Open Access

    The effect of the liver clock is modified by food entrainment via Bmal1/Clock core machinery. Here the authors show that insulin promotes postprandial Akt-dependent phosphorylation of Bmal1, resulting in association with 14-3-3 and Bmal1 shuttling out of the nucleus, thereby disrupting Bmal1 transcriptional effects on the clock.

    • Fabin Dang
    • , Xiujie Sun
    •  & Yi Liu
  • Article
    | Open Access

    The circadian rhythms of peripheral clocks are difficult to study. Here the authors demonstrate a technique to image clock gene expression simultaneously in various tissues of freely moving mice, and use it to show that a long duration light pulse resets the rhythms in the olfactory bulb faster than other tissues.

    • Toshiyuki Hamada
    • , Kenneth Sutherland
    •  & Ken-ichi Honma
  • Article
    | Open Access

    Circadian rhythms synchronize important biological processes, and are thought to primarily be entrained by environmental cycles in light and temperature, with little or no role for social interactions. Here, Fuchikawa et al. show that social cues among honeybees can entrain these rhythms even in the presence of conflicting light-dark cycles.

    • Taro Fuchikawa
    • , Ada Eban-Rothschild
    •  & Guy Bloch
  • Article
    | Open Access

    Circadian rhythms are central to health and disease and there is renewed interest in chronotherapy. Here, the authors present a mouse with an artificial circadian clock that can be pharmacologically tuned, providing a tool for future studies of circadian biology and therapy.

    • Matthew D’Alessandro
    • , Stephen Beesley
    •  & Choogon Lee
  • Article
    | Open Access

    Bile acids are important for the absorption of nutrients. Here the authors provide a molecular explanation for the oscillatory release of bile acids, showing that diurnal expression of the transcription factor KLF15 regulates FGF15 secretion from enterocytes, which then inhibits bile acid synthesis in the liver.

    • Shuxin Han
    • , Rongli Zhang
    •  & Mukesh K. Jain
  • Article |

    The mammalian circadian clock is influenced by nuclear receptors such as Rev-Erb. Here Kumar et al. show that ecdysone-induced protein 75 (E75), a fly homologue of Rev-Erb, regulates circadian rhythms in Drosophila, and demonstrate that E75 protects the clock against environmental stressors.

    • Shailesh Kumar
    • , Dechun Chen
    •  & Amita Sehgal
  • Article |

    The CWO protein is part of a feedback loop that contributes to the high-amplitude circadian oscillation in Drosophila. Here, the authors identify microRNA let-7 as a regulator of circadian rhythm via repression of cwo, and show the circadian expression of let-7 is regulated by ecdysteroid and its receptor.

    • Wenfeng Chen
    • , Zhenxing Liu
    •  & Zhangwu Zhao
  • Article |

    Whether circadian rhythms occur in settings where clock gene expression is suppressed, such as systemic inflammation, is unclear. Here, the authors examine gene expression and metabolites in the lungs of endotoxemic mice and show that inflammation causes changes in circadian rhythms at the cellular and molecular level.

    • Jeffrey A. Haspel
    • , Sukrutha Chettimada
    •  & Augustine M.K. Choi
  • Article |

    Body clocks modulate physiological processes to follow a day–night cycle, but whether animals exposed to constant darkness express circadian rhythms is unknown. Here the authors examine the expression of circadian genes in Mexican cavefish, and find that these resemble a pattern expected from exposure to constant daylight.

    • Andrew Beale
    • , Christophe Guibal
    •  & David Whitmore
  • Article
    | Open Access

    Monarch Butterflies (Danaus plexippus) use their antennae for orientation during their autumnal migration. Guerra and colleagues differentially disrupt clock gene expression in each antenna and find that the individual outputs are integrated and processed to allow precise control of orientation behaviour.

    • Patrick A. Guerra
    • , Christine Merlin
    •  & Steven M. Reppert