Remarkable progress in ageing research has been achieved over the past decades. General perceptions and experimental evidence pinpoint that the decline of physical function often initiates by cell senescence and organ ageing. Epigenetic dynamics and immunometabolic reprogramming link to the alterations of cellular response to intrinsic and extrinsic stimuli, representing current hotspots as they not only (re-)shape the individual cell identity, but also involve in cell fate decision. This review focuses on the present findings and emerging concepts in epigenetic, inflammatory, and metabolic regulations and the consequences of the ageing process. Potential therapeutic interventions targeting cell senescence and regulatory mechanisms, using state-of-the-art techniques are also discussed.

Rationale: PGC1α (peroxisome proliferator-activated receptor gamma coactivator 1α) represents an attractive target interfering bioenergetics and mitochondrial homeostasis, yet multiple attempts have failed to upregulate PGC1α expression as a therapy, for instance, causing cardiomyopathy. Objective: To determine whether a fine-tuning of PGC1α expression is essential for cardiac homeostasis in a context-dependent manner. Methods and Results: Moderate cardiac-specific PGC1α overexpression through a ROSA26 locus knock-in strategy was utilized in WT (wild type) mice and in G3Terc −/− (third generation of telomerase deficient; hereafter as G3) mouse model, respectively. Ultrastructure, mitochondrial stress, echocardiographic, and a variety of biological approaches were applied to assess mitochondrial physiology and cardiac function. While WT mice showed a relatively consistent PGC1α expression from 3 to 12 months old, age-matched G3 mice exhibited declined PGC1α expression and compromised mitochondrial function. Cardiac-specific overexpression of PGC1α (PGC1α OE ) promoted mitochondrial and cardiac function in 3-month-old WT mice but accelerated cardiac aging and significantly shortened life span in 12-month-old WT mice because of increased mitochondrial damage and reactive oxygen species insult. In contrast, cardiac-specific PGC1α knock in in G3 (G3 PGC1α OE ) mice restored mitochondrial homeostasis and attenuated senescence-associated secretory phenotypes, thereby preserving cardiac performance with age and extending health span. Mechanistically, age-dependent defect in mitophagy is associated with accumulation of damaged mitochondria that leads to cardiac impairment and premature death in 12-month-old WT PGC1α OE mice. In the context of telomere dysfunction, PGC1α induction replenished energy supply through restoring the compromised mitochondrial biogenesis and thus is beneficial to old G3 heart. Conclusions: Fine-tuning the expression of PGC1α is crucial for the cardiac homeostasis because the balance between mitochondrial biogenesis and clearance is vital for regulating mitochondrial function and homeostasis. These results reinforce the importance of carefully evaluating the PGC1α-boosting strategies in a context-dependent manner to facilitate clinical translation of novel cardioprotective therapies.

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Susceptibility of gastrointestinal dysmotility increases with age-associated colonic degeneration. A paucity of remedies reversing colonic degeneration per se hinders the fundamental relief of symptoms. Here we discovered the correlation between colon degeneration and altered nicotinamide adenine dinucleotide (NAD) level in aged mice. Compared to 3-month-old young controls, 2-year-old mice showed a spectrum of degenerative colonic phenotypes and exhibited a significant elongated transit time and slowed stool frequency in the context of Lomotil-induced slow-transit constipation. Despite upregulated colonic tryptophan hydroxylases expression, serotonin release and expression of colon-predominant type IV serotonin receptor, reduced viability of interstitial cells of Cajal while enhanced aquaporins (Aqp1, 3 and 11) led to a less colonic motility and increased luminal dehydration in aged mice. Notably, this colonic degeneration was accompanied with reduced key NAD+-generating enzyme expression and lowered NAD+/NADH ratio in aged colon. Three-month continuous administration of beta nicotinamide mononucleotide, a NAD+ precursor, elevated colonic NAD+ level and improved defecation in aged mice. In contrast, pharmacological inhibition of nicotinamide phosphoribosyltransferase, the rate-limiting enzyme for NAD+ biosynthesis, induced a reduction in colonic NAD content and impaired gastrointestinal function in young mice. Taken together, these findings suggest the beneficial effect of NAD+ in maintaining colonic homoeostasis and reactivating NAD+ biosynthesis may represent a promising strategy to counteract age-related gastrointestinal degeneration.

The antidiabetic drug metformin exerts pleiotropic effects on multiple organs, including the cardiovascular system. Evidence has shown that metformin improves healthspan and lifespan in male mice, yet its lifespan lengthening effect in females remains elusive. We herein demonstrated that metformin fails to extend the lifespan in female mice. Compared to 2-month-old young controls, 20-month-old female mice showed a spectrum of degenerative cardiac phenotypes alongside significant alterations in the extracellular matrix composition. Despite lowered reactive oxygen species production, long-term metformin treatment did not improve cardiac function in the aged female mice. In contrast, RNA sequencing analyses demonstrated that metformin treatment elevated the extracellular matrix-related gene while lowering oxidative phosphorylation-related gene expression in the heart. In addition, metformin treatment induced metabolic reprogramming that suppressed mitochondrial respiration but activated glycolysis (i.e., Warburg effect) in cultured primary cardiomyocytes and macrophages, thereby sustaining an inflammatory status and lowering ATP production. These findings suggest the unexpected detrimental effects of metformin on the regulation of cardiac homeostasis and longevity in female mice, reinforcing the significance of comprehensive testing prior to the translation of metformin-based novel therapies.

5-HT- positive neurons were detected by the PAP immunohistochemical methods in different nuclei of the reticular formations of human fetuses as early as 10 weeks of gestation. The majority of positive 5-HT cells were located in dorsal raphe and central superior nuclei, and there was a reduction of these neurons per 40-µm section as the fetus aged.

Inflammatory responses are pivotal incidences in hepatic metabolic derangements. However, the underlying mechanism remains elusive. The present study aimed to evaluate the role of peroxisome proliferator-activated receptor-gamma, coactivator 1 alpha (PGC1α) in IL10-mediated anti-inflammatory response, and its role in hepatic steatosis and insulin resistance. Hepatocyte-specific PGC1α knock-in (LivPGC1α)