bims-ciryme 2023-04-02 papers

Commun Biol. 2023 Mar 27. 6(1): 332

The circadian clock in the piriform cortex intrinsically tunes daily changes of odor-evoked neural activity.

Shunsuke Takeuchi, Kimiko Shimizu, Yoshitaka Fukada, Kazuo Emoto.

The daily activity in the brain is typically fine-tuned by the circadian clock in the local neurons as well as by the master circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. In the olfactory response, odor-evoked activity in the piriform cortex (PC) and olfactory behavior retain circadian rhythmicity in the absence of the SCN, yet how the circadian rhythm in the PC is achieved independently of the SCN remains elusive. Here, to define neurons regulating the circadian rhythm of the odor-evoked activity in the PC, we knocked out the clock gene Bmal1 in a host of specific neurons along the olfactory circuit. We discovered that Bmal1 knockout in the PC largely abolishes the circadian rhythm of the odor-evoked activity. We further showed that isolated PC exhibits sustained circadian rhythms of the clock gene Per2 expression. Quantitative PCR analysis revealed that expression patterns of multiple genes involved in neural activity and synaptic transmission exhibit circadian rhythm in the PC in a BMAL1-dependent manner. Our findings indicate that BMAL1 acts intrinsically in the PC to control the circadian rhythm of the odor-evoked activity in the PC, possibly through regulating expression patterns of multiple genes involved in neural activity and transmission.

DOI: https://doi.org/10.1038/s42003-023-04691-8

Biology (Basel). 2023 Feb 28. pii: 383. [Epub ahead of print]12(3):

Circle(s) of Life: The Circadian Clock from Birth to Death.

Iwona Olejniczak, Violetta Pilorz, Henrik Oster.

Most lifeforms on earth use endogenous, so-called circadian clocks to adapt to 24-h cycles in environmental demands driven by the planet's rotation around its axis. Interactions with the environment change over the course of a lifetime, and so does regulation of the circadian clock system. In this review, we summarize how circadian clocks develop in humans and experimental rodents during embryonic development, how they mature after birth and what changes occur during puberty, adolescence and with increasing age. Special emphasis is laid on the circadian regulation of reproductive systems as major organizers of life segments and life span. We discuss differences in sexes and outline potential areas for future research. Finally, potential options for medical applications of lifespan chronobiology are discussed.

Keywords: adolescence; adulthood; aging; childhood; circadian clock; infancy; prenatal development

DOI: https://doi.org/10.3390/biology12030383

Nat Commun. 2023 Mar 27. 14(1): 1685

Time-of-day defines NAD+ efficacy to treat diet-induced metabolic disease by synchronizing the hepatic clock in mice.

Quetzalcoatl Escalante-Covarrubias, Lucía Mendoza-Viveros, Mirna González-Suárez, Román Sitten-Olea, Laura A Velázquez-Villegas, Fernando Becerril-Pérez, Ignacio Pacheco-Bernal, Erick Carreño-Vázquez, Paola Mass-Sánchez, Marcia Bustamante-Zepeda, Ricardo Orozco-Solís, Lorena Aguilar-Arnal.

The circadian clock is an endogenous time-tracking system that anticipates daily environmental changes. Misalignment of the clock can cause obesity, which is accompanied by reduced levels of the clock-controlled, rhythmic metabolite NAD+. Increasing NAD+ is becoming a therapy for metabolic dysfunction; however, the impact of daily NAD+ fluctuations remains unknown. Here, we demonstrate that time-of-day determines the efficacy of NAD+ treatment for diet-induced metabolic disease in mice. Increasing NAD+ prior to the active phase in obese male mice ameliorated metabolic markers including body weight, glucose and insulin tolerance, hepatic inflammation and nutrient sensing pathways. However, raising NAD+ immediately before the rest phase selectively compromised these responses. Remarkably, timed NAD+ adjusted circadian oscillations of the liver clock until completely inverting its oscillatory phase when increased just before the rest period, resulting in misaligned molecular and behavioral rhythms in male and female mice. Our findings unveil the time-of-day dependence of NAD+-based therapies and support a chronobiology-based approach.

DOI: https://doi.org/10.1038/s41467-023-37286-2

Proc Natl Acad Sci U S A. 2023 Apr 04. 120(14): e2220102120

NAMPT-dependent NAD+ biosynthesis controls circadian metabolism in a tissue-specific manner.

Astrid L Basse, Karen N Nielsen, Iuliia Karavaeva, Lars R Ingerslev, Tao Ma, Jesper F Havelund, Thomas S Nielsen, Mikkel Frost, Julia Peics, Emilie Dalbram, Morten Dall, Juleen R Zierath, Romain Barrès, Nils J Færgeman, Jonas T Treebak, Zachary Gerhart-Hines.

Molecular clocks in the periphery coordinate tissue-specific daily biorhythms by integrating input from the hypothalamic master clock and intracellular metabolic signals. One such key metabolic signal is the cellular concentration of NAD+, which oscillates along with its biosynthetic enzyme, nicotinamide phosphoribosyltransferase (NAMPT). NAD+ levels feed back into the clock to influence rhythmicity of biological functions, yet whether this metabolic fine-tuning occurs ubiquitously across cell types and is a core clock feature is unknown. Here, we show that NAMPT-dependent control over the molecular clock varies substantially between tissues. Brown adipose tissue (BAT) requires NAMPT to sustain the amplitude of the core clock, whereas rhythmicity in white adipose tissue (WAT) is only moderately dependent on NAD+ biosynthesis, and the skeletal muscle clock is completely refractory to loss of NAMPT. In BAT and WAT, NAMPT differentially orchestrates oscillation of clock-controlled gene networks and the diurnality of metabolite levels. NAMPT coordinates the rhythmicity of TCA cycle intermediates in BAT, but not in WAT, and loss of NAD+ abolishes these oscillations similarly to high-fat diet-induced circadian disruption. Moreover, adipose NAMPT depletion improved the ability of animals to defend body temperature during cold stress but in a time-of-day-independent manner. Thus, our findings reveal that peripheral molecular clocks and metabolic biorhythms are shaped in a highly tissue-specific manner by NAMPT-dependent NAD+ synthesis.

Keywords: Brown adipose tissue; Circadian metabolism; Clock rhythm; NAD; Skeletal muscle

DOI: https://doi.org/10.1073/pnas.2220102120