The role of clock genes in cardiometabolic disease

The Effect of Personality on Chrononutrition during the COVID-19 Lockdown in Qatar

The COVID-19 lockdown has had a significant impact on people's lives worldwide. This study aimed to investigate the effect of personality on chrononutrition during the COVID-19 lockdown. Using a cross-sectional design, a convenient sample of 543 adults in Qatar completed an online questionnaire using validated tools to assess personality and chrononutrition behaviors during the first COVID-19 lockdown. Participants scoring high in openness were more likely to eat at night (mean difference (MD) = 0.41, 95% confidence interval (CI): 0.10, 0.72) compared to those scoring high in agreeableness, while those scoring high in extraversion and openness had a shorter eating window (MD = -76.6, 95%CI: -146.3, -6.93 and MD = -29.8, 95%CI: -56.5, -3.01, respectively). Participants high in extraversion had longer evening latency (MD = 66.3, 95%CI: 25.4, 107.3) and evening eating (MD = -62.0, 95%CI: -114.0, -9.0) compared those high in agreeableness. Participants high in conscientiousness showed evidence of first eating event misalignment during the weekend (MD = 22.0, 95%CI: 0.15, 43.9) and last eating event misalignment during weekdays (MD = -27.8, 95%CI: -47.3, -8.41) compared to those high in agreeableness. Lastly, participants high in openness showed evidence of eating window misalignment during the weekend (MD = 30.6, 95%CI: 5.01, 56.2). This study suggests that personality traits can inform personalized nutritional approaches when aiming for healthy habits during unexpected periods, such as the COVID-19 pandemic.

Transcriptional control of antioxidant defense by the circadian clock

SIGNIFICANCE

The circadian clock, an internal timekeeping system, is implicated in the regulation of metabolism and physiology, and circadian dysfunctions are associated with pathological changes in model organisms and increased risk of some diseases in humans.

RECENT ADVANCES

Data obtained in different organisms, including humans, have established a tight connection between the clock and cellular redox signaling making it among the major candidates for a link between the circadian system and physiological processes.

CRITICAL ISSUES

In spite of the recent progress in understanding the importance of the circadian clock in the regulation of reactive oxygen species homeostasis, molecular mechanisms and key regulators are mostly unknown.

FUTURE DIRECTIONS

Here we review, with an emphasis on transcriptional control, the circadian-clock-dependent control of oxidative stress response system as a potential mechanism in age-associated diseases. We will discuss the roles of the core clock components such as brain and muscle ARNT-like 1, Circadian Locomotor Output Cycles Kaput, the circadian-clock-controlled transcriptional factors such as nuclear factor erythroid-2-related factor, and peroxisome proliferator-activated receptor and circadian clock control chromatin modifying enzymes from sirtuin family in the regulation of cellular and organism antioxidant defense.

Cardioprotection via preserved mitochondrial structure and function in the mPer2-mutant mouse myocardium

We have previously shown that myocardial infarct size in nonreperfused hearts of mice with a functional deletion of the circadian rhythm gene mPer2 (mPer2-M) was reduced by 43%. We hypothesized that acute ischemia-reperfusion injury (I/R = 30 min I/2 h R) would also be reduced in these mice and that ischemic preconditioning (IPC) (3 × 5 min cycles) before I/R, which enhances protection in wild-type (WT) hearts, would provide further protection in mPer2-M hearts. We observed a 69 and 75% decrease in infarct size in mPer2-M mouse hearts compared with WT following I/R and IPC, respectively. This was coincident with 67% less neutrophil infiltration and 57% less apoptotic cardiomyocytes. IPC in mPer2-M mice before I/R had 48% less neutrophil density and 46% less apoptosis than their WT counterparts. Macrophage density was not different between WT and mPer2-M I/R, but it was 45% higher in mPer2-M IPC mouse hearts compared with WT IPC. There were no baseline differences in cardiac mitochondrial function between WT and mPer2-M mice, but, following I/R, WT exhibited a marked decrease in maximal O₂ consumption supported by complex I-mediated substrates, whereas mPer2-M did not, despite no difference in complex I content. Moreover, cardiac mitochondria from WT mice exhibited a very robust increase in ADP-stimulated O₂ consumption in response to exogenously added cytochrome c, along with a high rate of reactive oxygen species production, none of which was exhibited by cardiac mitochondria from mPer2-M following I/R. Taken together, these findings suggest that mPer2 deletion preserves mitochondrial membrane structure and functional integrity in heart following I/R injury, the consequence of which is preservation of myocardial viability. Understanding the mechanisms connecting cardiac events, mitochondrial function, and mPer2 could lead to preventative and therapeutic strategies for at risk populations.

High sleep duration variability is an independent risk factor for weight gain

OBJECTIVE

This study was conducted to evaluate the association between weight gain and variability of sleep duration.

METHODS

A retrospective cohort study was conducted involving apparently healthy individuals aged 20 years or older who underwent annual health checkup at the Center for Preventive Medicine, St. Luke's International Hospital, between 2007 and 2010. The body mass index (BMI) of each participant was measured, and the change in BMI during the study period was calculated. The sleep duration was obtained using a questionnaire that was filled out by participants each year, and the variability in the sleep duration was calculated by dividing the standard deviation (SD) of the sleep duration for 3 years by the square root of the number of data points. Multivariate linear regression analysis was used to explore the association between the change in BMI and the variability of the sleep duration, adjusting for age, sex, alcohol consumption, current smoking, baseline sleep duration, past medical history, and level of physical activity.

RESULTS

A total of 21,148 participants were included in this study. The mean age (SD) was 51 (12) years, and 10,993 (49.6%) participants were male. The mean baseline BMI was 22.4 (SD 3.2). According to the self-reported data, the mean sleep duration (SD) was 6.2 (1.0) h, and the mean of the SD of sleep duration for each participant was 0.32 (min-max, 0-7). The result of the linear regression analysis showed that greater variability in the sleep duration was independently related to an increase in BMI (β coefficient = 0.31; 95% CI = 0.01-0.61).

CONCLUSION

The variability of sleep duration is related to body weight gain. Maintaining a constant sleep duration may be recommended for controlling body weight.

SirT1 in muscle physiology and disease: lessons from mouse models

Sirtuin 1 (SirT1) is the largest of the seven members of the sirtuin family of class III nicotinamide adenine dinucleotide (NAD(+))-dependent protein deacetylases, whose activation is beneficial for metabolic, neurodegenerative, inflammatory and neoplastic diseases, and augments life span in model organisms (Finkel et al., 2009; Lavu et al., 2008). In vitro studies show that SirT1 protects genome integrity and is involved in circadian physiological rhythms (Asher et al., 2008; Nakahata et al., 2008; Oberdoerffer et al., 2008). In the last few years, a fundamental role for SirT1 in the metabolism and differentiation of skeletal muscle cells has been uncovered (Fulco et al., 2003), and the use of specific transgenic or knockout SirT1 mouse models implicates it in the protection of heart muscle from oxidative and hypertrophic stresses (Alcendor et al., 2007). In this Perspective, we review the recent exciting findings that have established a key role for the 'longevity' protein SirT1 in skeletal and heart muscle physiology and disease. Furthermore, given the multiple biological functions of SirT1, we discuss the unique opportunities that SirT1 mouse models can offer to improve our integrated understanding of the metabolism, as well as the regeneration and aging-associated changes in the circadian function, of skeletal and heart muscle.