PARP-1 Inhibition Rescues Short Lifespan in Hyperglycemic C. Elegans And Improves GLP-1 Secretion in Human Cells

Involvement of regulated cell deaths in aging and age-related pathologies

Aging is a pathophysiological process that causes a gradual and permanent reduction in all biological system functions. The phenomenon is caused by the accumulation of endogenous and exogenous damage as a result of several stressors, resulting in significantly increased risks of various age-related diseases such as neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. In addition, aging appears to be connected with mis-regulation of programmed cell death (PCD), which is required for regular cell turnover in many tissues sustained by cell division. According to the recent nomenclature, PCDs are physiological forms of regulated cell death (RCD) useful for normal tissue development and turnover. To some extent, some cell types are connected with a decrease in RCD throughout aging, whereas others are related with an increase in RCD. Perhaps the widespread decline in RCD markers with age is due to a slowdown of the normal rate of homeostatic cell turnover in various adult tissues. As a result, proper RCD regulation requires a careful balance of many pro-RCD and anti-RCD components, which may render cell death signaling pathways more sensitive to maladaptive signals during aging. Current research, on the other hand, tries to further dive into the pathophysiology of aging in order to develop therapies that improve health and longevity. In this scenario, RCD handling might be a helpful strategy for human health since it could reduce the occurrence and development of age-related disorders, promoting healthy aging and lifespan. In this review we propose a general overview of the most recent RCD mechanisms and their connection with the pathophysiology of aging in order to promote targeted therapeutic strategies.

Comorbidity Genes of Alzheimer's Disease and Type 2 Diabetes Associated with Memory and Cognitive Function

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are comorbidities that result from the sharing of common genes. The molecular background of comorbidities can provide clues for the development of treatment and management strategies. Here, the common genes involved in the development of the two diseases and in memory and cognitive function are reviewed. Network clustering based on protein-protein interaction network identified tightly connected gene clusters that have an impact on memory and cognition among the comorbidity genes of AD and T2DM. Genes with functional implications were intensively reviewed and relevant evidence summarized. Gene information will be useful in the discovery of biomarkers and the identification of tentative therapeutic targets for AD and T2DM.

Biochemical Targets and Molecular Mechanism of Matrine against Aging

The aim of this study is to explore the potential targets and molecular mechanism of matrine (MAT) against aging. Bioinformatic-based network pharmacology was used to investigate the aging-related targets and MAT-treated targets. A total of 193 potential genes of MAT against aging were obtained and then the top 10 key genes (cyclin D1, cyclin-dependent kinase 1, Cyclin A2, androgen receptor, Poly [ADP-ribose] polymerase-1 (PARP1), histone-lysine N-methyltransferase, albumin, mammalian target of rapamycin, histone deacetylase 2, and matrix metalloproteinase 9) were filtered by the molecular complex detection, maximal clique centrality (MMC) algorithm, and degree. The Metascape tool was used for analyzing biological processes and pathways of the top 10 key genes. The main biological processes were response to an inorganic substance and cellular response to chemical stress (including cellular response to oxidative stress). The major pathways were involved in cellular senescence and the cell cycle. After an analysis of major biological processes and pathways, it appears that PARP1/nicotinamide adenine dinucleotide (NAD⁺)-mediated cellular senescence may play an important role in MAT against aging. Molecular docking, molecular dynamics simulation, and in vivo study were used for further investigation. MAT could interact with the cavity of the PARP1 protein with the binding energy at -8.5 kcal/mol. Results from molecular dynamics simulations showed that the PARP1-MAT complex was more stable than PARP1 alone and that the binding-free energy of the PARP1-MAT complex was -15.962 kcal/mol. The in vivo study showed that MAT could significantly increase the NAD⁺ level of the liver of d-gal-induced aging mice. Therefore, MAT could interfere with aging through the PARP1/NAD⁺-mediated cellular senescence signaling pathway.

Poly(ADP-ribose) polymerase-1 and its ambiguous role in cellular life and death

The deletion of the gene coding for poly(ADP-ribose) polymerase-1 (PARP1) or its pharmacological inhibition protects mice against cerebral ischemia and Parkinson's disease. In sharp contrast, PARP1 inhibitors are in clinical use for the eradication of vulnerable cancer cells. It appears that excessive PARP1 activation is involved in a specific cell death pathway called parthanatos, while inhibition of PARP1 in cancer cells amplifies DNA damage to a lethal level. Hence, PARP1 plays a context-dependent role in cell fate decisions. In addition, it appears that PARP1 plays an ambiguous role in organismal aging.

Bidirectional regulation role of PARP-1 in high glucose-induced endothelial injury

Loss of poly (ADP-ribose) polymerase-1 (PARP-1) has been found to slow the progression of diabetes and diabetic angiopathy. In our study, we found bidirectional regulation of PARP-1 in high glucose induced endothelial injury, which promoting repair at the early stage of injury and inhibiting repair at the late stage of injury. To further investigate the mechanism of PARP-1 regulation, we first examined the expression of PARP-1 in aortic tissues and cultured cells at early, middle, and late stages of injury, PARP-1 expression was significantly greater than that of control group. Overexpression of PARP-1 in HUVECs significantly reduced the number of apoptotic cells 12 h after high glucose injury, while reducing the level of reactive oxygen species (ROS)/malondialdehyde (MDA)/inducible nitric oxide synthase (iNOS), increasing the level of endothelial nitric oxide synthase (eNOS); however, when the injury extended to 3 days, the number of apoptosis in HUVECs overexpressing PARP-1 was significantly higher than that in the injury group, and the level of ROS/MDA/iNOS was significantly higher, while the secretion of eNOS was significantly lower. Similarly, PARP-1 inhibitors aggravate early damage and inhibit late damage. We found that PARP-1 promoted the activation of P53 and P53R2 in endothelial cells after 12 h of injury, and PARP-1 promoted the activation of P53 and caspas3 in endothelial cells after 3 days of injury. Therefore, we suggest that PARP-1 plays a dual regulatory role in promoting repair or aggravating injury.

C. elegans as a model organism to study female reproductive health

Female reproductive health has been historically understudied and underfunded. Here, we present the advantages of using a free-living nematode, Caenorhabditis elegans, as an animal system to study fundamental aspects of female reproductive health. C. elegans is a powerful high-throughput model organism that shares key genetic and physiological similarities with humans. In this review, we highlight areas of pressing medical and biological importance in the 21st century within the context of female reproductive health. These include the decline in female reproductive capacity with increasing chronological age, reproductive dysfunction arising from toxic environmental insults, and cancers of the reproductive system. C. elegans has been instrumental in uncovering mechanistic insights underlying these processes, and has been valuable for developing and testing therapeutics to combat them. Adopting a convenient model organism such as C. elegans for studying reproductive health will encourage further research into this field, and broaden opportunities for making advancements into evolutionarily conserved mechanisms that control reproductive function.

NAD+ metabolism and its roles in cellular processes during ageing

Nicotinamide adenine dinucleotide (NAD⁺) is a coenzyme for redox reactions, making it central to energy metabolism. NAD⁺ is also an essential cofactor for non-redox NAD⁺-dependent enzymes, including sirtuins, CD38 and poly(ADP-ribose) polymerases. NAD⁺ can directly and indirectly influence many key cellular functions, including metabolic pathways, DNA repair, chromatin remodelling, cellular senescence and immune cell function. These cellular processes and functions are critical for maintaining tissue and metabolic homeostasis and for healthy ageing. Remarkably, ageing is accompanied by a gradual decline in tissue and cellular NAD⁺ levels in multiple model organisms, including rodents and humans. This decline in NAD⁺ levels is linked causally to numerous ageing-associated diseases, including cognitive decline, cancer, metabolic disease, sarcopenia and frailty. Many of these ageing-associated diseases can be slowed down and even reversed by restoring NAD⁺ levels. Therefore, targeting NAD⁺ metabolism has emerged as a potential therapeutic approach to ameliorate ageing-related disease, and extend the human healthspan and lifespan. However, much remains to be learnt about how NAD⁺ influences human health and ageing biology. This includes a deeper understanding of the molecular mechanisms that regulate NAD⁺ levels, how to effectively restore NAD⁺ levels during ageing, whether doing so is safe and whether NAD⁺ repletion will have beneficial effects in ageing humans.

NAD+ homeostasis in health and disease

The conceptual evolution of nicotinamide adenine dinucleotide (NAD⁺) from being seen as a simple metabolic cofactor to a pivotal cosubstrate for proteins regulating metabolism and longevity, including the sirtuin family of protein deacylases, has led to a new wave of scientific interest in NAD⁺. NAD⁺ levels decline during ageing, and alterations in NAD⁺ homeostasis can be found in virtually all age-related diseases, including neurodegeneration, diabetes and cancer. In preclinical settings, various strategies to increase NAD⁺ levels have shown beneficial effects, thus starting a competitive race to discover marketable NAD⁺ boosters to improve healthspan and lifespan. Here, we review the basics of NAD⁺ biochemistry and metabolism, and its roles in health and disease, and we discuss current challenges and the future translational potential of NAD⁺ research.

The TCF7L2 Locus: A Genetic Window Into the Pathogenesis of Type 1 and Type 2 Diabetes

Over the past ∼15 years there has been great progress in our understanding of the genetics of both type 1 diabetes and type 2 diabetes. This has been driven principally by genome-wide association studies (GWAS) in increasingly larger sample sizes, where many distinct loci have now been reported for both traits. One of the loci that dominates these studies is the TCF7L2 locus for type 2 diabetes. This genetic signal has been leveraged to explore multiple aspects of disease risk, including developments in genetic risk scores, genetic commonalities with cancer, and for gaining insights into diabetes-related molecular pathways. Furthermore, the TCF7L2 locus has aided in providing insights into the genetics of both latent autoimmune diabetes in adults and various presentations of type 1 diabetes. This review outlines the knowledge gained to date and highlights how work with this locus leads the way in guiding how many other genetic loci could be similarly used to gain insights into the pathogenesis of diabetes.

PJ34, a PARP1 inhibitor, promotes endothelial repair in a rabbit model of high fat diet-induced atherosclerosis

Objective: Atherosclerosis involves endothelial injury caused by oxidative stress. Endothelial progenitor cells (EPCs) play important roles in preventing the early stages of atherosclerosis. Meanwhile, poly (ADP-ribose) polymerase 1 (PARP1) utilizes nicotinamide adenine dinucleotide (NAD⁺) to repair DNA damage. PARP1 overactivation results in excessive NAD⁺ consumption in the presence of pathological DNA damage. PJ34 is a PARP1 inhibitor that attenuates cellular NAD+ depletion and can prevent endothelial dysfunction. However, few studies have been conducted on its effects on EPCs. In this study, we tried to elucidate the action of PJ34 in rabbit EPCs and tested its effectiveness in rabbit atherosclerosis. Methods: We analyzed the effect of PJ34 supplementation by inducing oxidative damage by H₂O₂ in vitro and using a rabbit atherosclerosis model induced by a high-fat-diet in vivo. Transwell, immunofluorescence, Matrigel, and western blot analyses, as well as adenoviral vector transfection were used to quantify the levels of reactive oxygen species, proteins, and NAD⁺. Results: The effects of PJ34 were dependent on SIRT1 levels. In vitro results showed that when oxidative damage attenuated cellular function, PJ34 treatment restored partial functionality. In vivo results confirmed that PJ34 can prevent atherosclerosis in a rabbit model.

Evaluation of the effects of three sulfa sweeteners on the lifespan and intestinal fat deposition in C. elegans

High sugar content in beverage or food can affect the aging process, and thus natural/artificial sweeteners are widely used as substitutes. However, whether sweeteners have such adverse effects as sugar remains to be clarified. Therefore, in the current study, three sulfa sweeteners, namely, saccharin sodium salt hydrate (SAC²), sodium cyclamate (CYC³) and acesulfame potassium (AceK⁴) were evaluated for their effects on the lifespan, deposition of lipofuscin, exercise activity, food intake, and intestinal fat deposition (IFD⁵) of Caenorhabditis elegans (C. elegans⁶). It was shown that SAC at 0.3 and 10 mg/mL shortened the lifespan of C. elegans and impaired the exercise capacity, while at other concentrations no significant effects were observed. In contrast, CYC at 0.1, 1 and 10 mg/mL prolonged the lifespan of C. elegans. On the other hand, AceK at 1 mg/mL increased the lifespan of C. elegans, and could decrease both lipofuscin deposition and IFD in a dose-dependent manner. Taken together, these results indicated that although SAC, CYC, and AceK all belong to the sulfa sweeteners, each has distinct effects on different physiological activities associated with aging, at least in C. elegans.

Metabolites related to purine catabolism and risk of type 2 diabetes incidence; modifying effects of the TCF7L2-rs7903146 polymorphism

Studies examining associations between purine metabolites and type 2 diabetes (T2D) are limited. We prospectively examined associations between plasma levels of purine metabolites with T2D risk and the modifying effects of transcription factor-7-like-2 (TCF7L2) rs7903146 polymorphism on these associations. This is a case-cohort design study within the PREDIMED study, with 251 incident T2D cases and a random sample of 694 participants (641 non-cases and 53 overlapping cases) without T2D at baseline (median follow-up: 3.8 years). Metabolites were semi-quantitatively profiled with LC-MS/MS. Cox regression analysis revealed that high plasma allantoin levels, including allantoin-to-uric acid ratio and high xanthine-to-hypoxanthine ratio were inversely and positively associated with T2D risk, respectively, independently of classical risk factors. Elevated plasma xanthine and inosine levels were associated with a higher T2D risk in homozygous carriers of the TCF7L2-rs7903146 T-allele. The potential mechanisms linking the aforementioned purine metabolites and T2D risk must be also further investigated.