Time of day determines postexercise metabolism in mouse adipose tissue

Novel insights into the circadian modulation of lipid metabolism in chicken livers revealed by RNA sequencing and weighted gene co-expression network analysis

The circadian clock is crucial for maintaining lipid metabolism homeostasis in mammals. Despite the economic importance of fat content in poultry, research on the regulatory effects and molecular mechanisms of the circadian clock on avian hepatic lipid metabolism has been limited. In this study, we observed significant diurnal variations (P<0.05) in triglyceride (TG), free fatty acids (FFA), fatty acid synthase (FAS), and total cholesterol (TC) levels in the chicken embryonic liver under 12-h light/12-h dark incubation conditions, with TG, FFA, and TC concentrations showing significant cosine rhythmic oscillations (P<0.05). However, such rhythmic variations were not observed under complete darkness incubation conditions. Using transcriptome sequencing technology, we identified 157 genes significantly upregulated at night and 313 genes significantly upregulated during the 12-h light/12-h dark cycle. These circadian differential genes are involved in processes and pathways such as lipid catabolic process regulation, meiotic cell cycle, circadian rhythm regulation, positive regulation of the MAPK cascade, and glycerolipid metabolism. Weighted gene co-expression network analysis (WGCNA) revealed 3 modules-green, blue, and red-that significantly correlate with FFA, FAS, and TG, respectively. Genes within these modules were enriched in processes and pathways including the cell cycle, light stimulus response, circadian rhythm regulation, phosphorylation, positive regulation of the MAPK cascade, and lipid biosynthesis. Notably, we identified ten hub genes, including protein kinase C delta (PRKCD), polo like kinase 4 (PLK4), clock circadian regulator (CLOCK), steroid 5 alpha-reductase 3 (SRD5A3), BUB1 mitotic checkpoint serine/threonine kinase (BUB1B), shugoshin 1 (SGO1), NDC80 kinetochore complex component (NDC80), NIMA related kinase 2 (NEK2), minichromosome maintenance complex component 4 (MCM4), polo like kinase 1 (PLK1), potentially link circadian regulation with lipid metabolic homeostasis. These findings demonstrate the regulatory role of the circadian clock in chicken liver lipid metabolism homeostasis and provide a theoretical basis and molecular targets for optimizing the circadian clock to reduce excessive fat deposition in chickens, which is significant for the healthy development of the poultry industry.

Nutrition and exercise: Cornerstones of health with emphasis on obesity and type 2 diabetes management-A narrative review

While a broad consensus exists that integrated nutrition and regular exercise are foundational for health maintenance and serve as a robust non-pharmacological strategy against cardiometabolic diseases, the nuanced interplay between these elements remains incompletely understood. Through multifaceted interactions, these factors profoundly influence primary metabolic organs, notably the skeletal muscle and adipose tissue. Despite the critical nature of this interactivity, a holistic understanding of the combined effects of physical activity and dietary practices is still emerging. This narrative review aims to elucidate the intertwined roles of nutrition and exercise. It provides a comprehensive overview of their synergistic dynamics and emphasizes the importance of a dual-focus approach in mitigating and managing cardiometabolic disorders, predominantly obesity and type 2 diabetes.

Mitochondrial UCP1: Potential thermogenic mechanistic switch for the treatment of obesity and neurodegenerative diseases using natural and epigenetic drug candidates

BACKGROUND

Brown fat is known to provide non-shivering thermogenesis through mitochondrial uncoupling mediated by uncoupling protein 1 (UCP1). Non-shivering is not dependent on UCP2, UCP4, and BMCP1/UCP5 genes, which are distinct from UCP1 in a way that they are not constitutive uncouplers. Although they are susceptible to free fatty acid and free radical activation, their functioning has a significant impact on the performance of neurons.

METHODOLOGY

Using subject-specific keywords (Adipose tissue; Adipocytes; Mitochondria; Obesity; Thermogenesis; UCP's in Neurodegeneration; Alzheimer's disease; Parkinson's disease), research articles and reviews were retrieved from Web of Science, ScienceDirect, Google Scholar, and PubMed. This article includespublications published between 2018 and 2023. The drugs that upregulate UCP1 are included in the study while the drugs that do not impact UCP1 are were not included.

RESULTS

Neuronal UCPs have a direct impact on synaptic plasticity, neurodegenerative processes, and neurotransmission, by modulating calcium flux, mitochondrial biogenesis, local temperature, and free radical generation. Numerous significant advances in the study of neuronal UCPs and neuroprotection are still to be made. Identification of the tissue-dependent effects of UCPs is essential first. Pharmacologically targeting neuronal UCPs is a key strategy for preventing both neurodegenerative diseases and physiological aging. Given that UCP2 has activities that are tissue-specific, it will be essential to develop treatments without harmful side effects. The triggering of UCPs by CoQ, an essential cofactor, produces nigral mitochondrial uncoupling, reduces MPTP-induced toxicity, and may even decrease the course of Parkinson's disease, according to early indications.

CONCLUSION

Herein, we explore the potential of UCP1 as a therapeutic target for treating obesity, neurodegenerative diseases as well as a potential activator of both synthetic and natural drugs. A deeper knowledge of synaptic signaling and neurodegeneration may pave the way to new discoveries regarding the functioning and controlling of these genes.

Metabolic plasticity and obesity-associated changes in diurnal postexercise metabolism in mice

BACKGROUND

Circadian disruption is widespread and increases the risk of obesity. Timing of therapeutic interventions may promote coherent and efficient gating of metabolic processes and restore energy homeostasis.

AIM

To characterize the diurnal postexercise metabolic state in mice and to identify the influence of diet-induced obesity on identified outcomes.

METHODS

C57BL6/NTac male mice (6 wks of age) were fed a standard chow or high-fat diet for 5 weeks. At week 5, mice were subjected to a 60-min (16 m/min, 5 % incline) running bout (or sham) during the early rest (day) or early active (night) phase. Tissue and serum samples were collected immediately post-exercise (n = 6/group). In vivo glucose oxidation was measured after oral administration of 13C-glucose via 13CO2 exhalation analysis in metabolic cages. Basal and isoproterenol-stimulated adipose tissue lipolysis was assessed ex vivo for 1 h following exercise.

RESULTS

Lean mice displayed exercise-timing-specific plasticity in metabolic outcomes, including phase-specificity in systemic glucose metabolism and adipose-tissue-autonomous lipolytic activity depending on time of day. Conversely, obesity impaired temporal postexercise differences in whole-body glucose oxidation, as well as the phase- and exercise-mediated induction of lipolysis in isolated adipose tissue. This obesity-induced alteration in diurnal metabolism, as well as the indistinct response to exercise, was observed concomitant with disruption of core clock gene expression in peripheral tissues.

CONCLUSIONS

Overall, high-fat fed obese mice exhibit metabolic inflexibility, which is also evident in the diurnal exercise response. Our study provides physiological insight into exercise timing-dependent aspects in the dynamic regulation of metabolism and the influence of obesity on this biology.

Circadian Rhythms in Cardiovascular Metabolism

Energetic demand and nutrient supply fluctuate as a function of time-of-day, in alignment with sleep-wake and fasting-feeding cycles. These daily rhythms are mirrored by 24-hour oscillations in numerous cardiovascular functional parameters, including blood pressure, heart rate, and myocardial contractility. It is, therefore, not surprising that metabolic processes also fluctuate over the course of the day, to ensure temporal needs for ATP, building blocks, and metabolism-based signaling molecules are met. What has become increasingly clear is that in addition to classic signal-response coupling (termed reactionary mechanisms), cardiovascular-relevant cells use autonomous circadian clocks to temporally orchestrate metabolic pathways in preparation for predicted stimuli/stresses (termed anticipatory mechanisms). Here, we review current knowledge regarding circadian regulation of metabolism, how metabolic rhythms are synchronized with cardiovascular function, and whether circadian misalignment/disruption of metabolic processes contribute toward the pathogenesis of cardiovascular disease.

Exercise-induced crosstalk between immune cells and adipocytes in humans: Role of oncostatin-M

The discovery of exercise-regulated circulatory factors has fueled interest in organ crosstalk, especially between skeletal muscle and adipose tissue, and the role in mediating beneficial effects of exercise. We studied the adipose tissue transcriptome in men and women with normal glucose tolerance or type 2 diabetes following an acute exercise bout, revealing substantial exercise- and time-dependent changes, with sustained increase in inflammatory genes in type 2 diabetes. We identify oncostatin-M as one of the most upregulated adipose-tissue-secreted factors post-exercise. In cultured human adipocytes, oncostatin-M enhances MAPK signaling and regulates lipolysis. Oncostatin-M expression arises predominantly from adipose tissue immune cell fractions, while the corresponding receptors are expressed in adipocytes. Oncostatin-M expression increases in cultured human Thp1 macrophages following exercise-like stimuli. Our results suggest that immune cells, via secreted factors such as oncostatin-M, mediate a crosstalk between skeletal muscle and adipose tissue during exercise to regulate adipocyte metabolism and adaptation.

Effects of exercise on circadian rhythms in humans

The biological clock system is an intrinsic timekeeping device that integrates internal physiology and external cues. Maintaining a healthy biological clock system is crucial for life. Disruptions to the body's internal clock can lead to disturbances in the sleep-wake cycle and abnormalities in hormone regulation, blood pressure, heart rate, and other vital processes. Long-term disturbances have been linked to the development of various common major diseases, including cardiovascular diseases, metabolic disorders, tumors, neuropsychiatric conditions, and so on. External factors, such as the diurnal rhythm of light, have a significant impact on the body's internal clock. Additionally, as an important non-photic zeitgeber, exercise can regulate the body's internal rhythms to a certain extent, making it possible to become a non-drug intervention for preventing and treating circadian rhythm disorders. This comprehensive review encompasses behavioral, physiological, and molecular perspectives to provide a deeper understanding of how exercise influences circadian rhythms and its association with related diseases.

Effects of exercise timing on metabolic health

The increasing prevalence of metabolic syndrome is associated with major health and socioeconomic consequences. Currently, physical exercise, together with dietary interventions, is the mainstay of the treatment of obesity and related metabolic complications. Although exercise training includes different modalities, with variable intensity, duration, volume, or frequency, which may have a distinct impact on several characteristics related to metabolic syndrome, the potential effects of exercise timing on metabolic health are yet to be fully elucidated. Remarkably, promising results with regard to this topic have been reported in the last few years. Similar to other time-based interventions, including nutritional therapy or drug administration, time-of-day-based exercise may become a useful approach for the management of metabolic disorders. In this article, we review the role of exercise timing in metabolic health and discuss the potential mechanisms that could drive the metabolic-related benefits of physical exercise performed in a time-dependent manner.

Organism-wide, cell-type-specific secretome mapping of exercise training in mice

There is a significant interest in identifying blood-borne factors that mediate tissue crosstalk and function as molecular effectors of physical activity. Although past studies have focused on an individual molecule or cell type, the organism-wide secretome response to physical activity has not been evaluated. Here, we use a cell-type-specific proteomic approach to generate a 21-cell-type, 10-tissue map of exercise training-regulated secretomes in mice. Our dataset identifies >200 exercise training-regulated cell-type-secreted protein pairs, the majority of which have not been previously reported. Pdgfra-cre-labeled secretomes were the most responsive to exercise training. Finally, we show anti-obesity, anti-diabetic, and exercise performance-enhancing activities for proteoforms of intracellular carboxylesterases whose secretion from the liver is induced by exercise training.

Circadian mechanisms in adipose tissue bioenergetics and plasticity

The circadian clock plays an essential role in coordinating feeding and metabolic rhythms with the light/dark cycle. Disruption of clocks is associated with increased adiposity and metabolic disorders, whereas aligning feeding time with cell-autonomous rhythms in metabolism improves health. Here, we provide a comprehensive overview of recent literature in adipose tissue biology as well as our understanding of molecular mechanisms underlying the circadian regulation of transcription, metabolism, and inflammation in adipose tissue. We highlight recent efforts to uncover the mechanistic links between clocks and adipocyte metabolism, as well as its application to dietary and behavioral interventions to improve health and mitigate obesity.