Calorie Restriction-Regulated Molecular Pathways and Its Impact on Various Age Groups: An Overview

Preconceptional paternal caloric restriction of high-fat diet-induced obesity in Wistar rats dysregulates the metabolism of their offspring via AMPK/SIRT1 pathway

BACKGROUND

Obesity is a metabolic syndrome where allelic and environmental variations together determine the susceptibility of an individual to the disease. Caloric restriction (CR) is a nutritional dietary strategy recognized to be beneficial as a weight loss regime in obese individuals. Preconceptional parental CR is proven to have detrimental effects on the health and development of their offspring. As yet studies on maternal CR effect on their offspring are well established but paternal CR studies are not progressing. In current study, the impact of different paternal CR regimes in diet-induced obese male Wistar rats (WNIN), on their offspring concerning metabolic syndrome are addressed.

METHODS

High-fat diet-induced obese male Wistar rats were subjected to caloric restriction of 50% (HFCR-I) and 40% (HFCR-II) and then they were mated with normal females. The male parent's reproductive function was assessed by sperm parameters and their DNMT's mRNA expression levels were also examined. The offspring's metabolic function was assessed by physiological, biochemical and molecular parameters.

RESULTS

The HFCR-I male parents have shown reduced body weights, compromised male fertility and reduced DNA methylation activity. Further, the HFCR-I offspring showed attenuation of the AMPK/SIRT1 pathway, which is associated with the progression of proinflammatory status and oxidative stress. In line, the HFCR-I offspring also developed altered glucose and lipid homeostasis by exhibiting impaired glucose tolerance & insulin sensitivity, dyslipidemia and steatosis. However, these effects were largely mitigated in HFCR-II offspring. Regarding the obesogenic effects, female offspring exhibited greater susceptibility than male offspring, suggesting that females are more prone to the influences of the paternal diet.

CONCLUSION

The findings highlight that HFCR-I resulted in paternal undernutrition, impacting the health of offspring, whereas HFCR-II largely restored the effects of a high-fat diet on their offspring. As a result, moderate caloric restriction has emerged as an effective weight loss strategy with minimal implications on future generations. This underscores the shared responsibility of fathers in contributing to sperm-specific epigenetic imprints that influence the health of adult offspring.

Long-term calorie restriction reduces oxidative DNA damage to oligodendroglia and promotes homeostatic microglia in the aging monkey brain

Calorie restriction (CR) is a robust intervention that can slow biological aging and extend lifespan. In the brain, terminally differentiated neurons and glia accumulate oxidative damage with age, reducing their optimal function. We investigated if CR could reduce oxidative DNA damage to white matter oligodendrocytes and microglia. This study utilized post-mortem brain tissue from rhesus monkeys that died after decades on a 30 % reduced calorie diet. We found that CR subjects had significantly fewer cells with oxidative damage within the corpus callosum and the cingulum bundle. Oligodendrocytes specifically showed the greatest response to CR with a robust reduction in DNA damage. Additionally, we observed alterations in microglia morphology with CR subjects having a higher proportion of ramified, homeostatic microglia and fewer pro-inflammatory, hypertrophic microglia relative to controls. Furthermore, we determined that the observed attenuation in damaged DNA occurs primarily within mitochondria. Overall, these data suggest that long-term CR can reduce oxidative DNA damage and offer a neuroprotective effect in a cell-type-specific manner in the aging monkey brain.

Dysregulation of miRNA-mRNA expression in fetal growth restriction in a caloric restricted mouse model

Fetal growth restriction (FGR) is associated with aberrant placentation and accounts for a significant proportion of perinatal deaths. microRNAs have been shown to be dysregulated in FGR. The purpose of this study was to determine microRNA-regulated molecular pathways altered using a caloric restricted mouse model of FGR. Pregnant mice were subjected to a 50% caloric restricted diet beginning at E9. At E18.5, RNA sequencing of placental tissue was performed to identify differences in gene expression between caloric restricted and control placentas. Significant differences in gene expression between caloric restricted and control placentas were observed in 228 of the 1546 (14.7%) microRNAs. Functional analysis of microRNA-mRNA interactions demonstrated enrichment of several biological pathways with oxidative stress, apoptosis, and autophagy pathways upregulated and angiogenesis and signal transduction pathways downregulated. Ingenuity pathway analysis also suggested that ID1 signaling, a pathway integral for trophoblast differentiation, is also dysregulated in caloric restricted placentas. Thus, a maternal caloric restriction mouse model of FGR results in aberrant microRNA-regulated molecular pathways associated with angiogenesis, oxidative stress, signal transduction, apoptosis, and cell differentiation. As several of these pathways are dysregulated in human FGR, our findings suggest that this model may provide an excellent means to study placental microRNA derangements seen in FGR.

Maackiain Mimics Caloric Restriction through aak-2-Mediated Lipid Reduction in Caenorhabditis elegans

Obesity prevalence is becoming a serious global health and economic issue and is a major risk factor for concomitant diseases that worsen the quality and duration of life. Therefore, the urgency of the development of novel therapies is of a particular importance. A previous study of ours revealed that the natural pterocarpan, maackiain (MACK), significantly inhibits adipogenic differentiation in human adipocytes through a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent mechanism. Considering the observed anti-adipogenic potential of MACK, we aimed to further elucidate the molecular mechanisms that drive its biological activity in a Caenorhabditis elegans obesity model. Therefore, in the current study, the anti-obesogenic effect of MACK (25, 50, and 100 μM) was compared to orlistat (ORST, 12 μM) as a reference drug. Additionally, the hybrid combination between the ORST (12 μM) and MACK (100 μM) was assessed for suspected synergistic interaction. Mechanistically, the observed anti-obesogenic effect of MACK was mediated through the upregulation of the key metabolic regulators, namely, the nuclear hormone receptor 49 (nhr-49) that is a functional homologue of the mammalian PPARs and the AMP-activated protein kinase (aak-2/AMPK) in C. elegans. Collectively, our investigation indicates that MACK has the potential to limit lipid accumulation and control obesity that deserves future developments.

Versatile function of AMPK signaling in osteosarcoma: An old player with new emerging carcinogenic functions

AMP-activated protein kinase (AMPK) signaling has a versatile role in Osteosarcoma (OS), an aggressive bone malignancy with a poor prognosis, particularly in cases that have metastasized or recurred. This review explores the regulatory mechanisms, functional roles, and therapeutic applications of AMPK signaling in OS. It focuses on the molecular activation of AMPK and its interactions with cellular processes like proliferation, apoptosis, and metabolism. The uncertain role of AMPK in cancer is also discussed, highlighting its potential as both a tumor suppressor and a contributor to carcinogenesis. The therapeutic potential of targeting AMPK signaling in OS treatment is examined, including direct and indirect activators like metformin, A-769662, resveratrol, and salicylate. Further research is needed to determine dosing, toxicities, and molecular mechanisms responsible for the anti-osteosarcoma effects of these compounds. This review underscores the complex involvement of AMPK signaling in OS and emphasizes the need for a comprehensive understanding of its molecular mechanisms. By elucidating the role of AMPK in OS, the aim is to pave the way for innovative therapeutic approaches that target this pathway, ultimately improving the prognosis and quality of life for OS patients.

Astrocytes as metabolic suppliers to support neuronal activity and brain functions

Energy metabolism is essential for brain function. In recent years, lactate shuttling between astrocytes and neurons has become a fundamental concept of neuroenergetics. However, it remains unclear to what extent this process is critical for different aspects of cognition, their underlying mechanisms, as well as for the signals used to monitor brain activation.