Inhibition of Adenylyl Cyclase Type 5 Increases Longevity and Healthful Aging through Oxidative Stress Protection

Nicotine Diminishes Alpha2-Adrenergic Receptor-Dependent Protection Against Oxidative Stress in H9c2 Cardiomyocytes

Introduction

Nicotine is a major component of cigarette smoke with various detrimental cardiovascular effects, including increased oxidative stress in the heart. Agonism of α2-adrenergic receptors (ARs), such as with dexmedetomidine, has been documented to exert cardioprotective effects against oxidative stress and related apoptosis and necroptosis. α2-ARs are membrane-residing G protein-coupled receptors (GPCRs) that primarily activate Gi/o proteins. They are also subjected to GPCR-kinase (GRK)-2-dependent desensitization, which entails phosphorylation of the agonist-activated receptor by GRK2 to induce its decoupling from G proteins, thus terminating α2AR-mediated G protein signaling.

Objective

In the present study, we sought to examine the effects of nicotine on α2AR signaling and effects in H9c2 cardiomyocytes exposed to H2O2 to induce oxidative cellular damage.

Methods and Results

As expected, treatment of H9c2 cardiomyocytes with H2O2 significantly decreased cell viability and increased oxidative stress, as assessed by reactive oxygen species (ROS)-associated fluorescence levels (DCF assay) and superoxide dismutase activity. Both H2O2 effects were partly rescued by α2AR activation with brimonidine in control cardiomyocytes but not in cells pretreated with nicotine for 24 hours, in which brimonidine was unable to reduce H2O2-induced cell death and oxidative stress. This was due to severe α2AR desensitization, manifested as very low Gi protein activation by brimonidine, and accompanied by GRK2 upregulation in nicotine-treated cardiomyocytes. Finally, pharmacological inhibition of adenylyl cyclase (AC) blocked H2O2-dependent oxidative damage in nicotine-pretreated H9c2 cardiomyocytes, indicating that α2AR activation protects against oxidative injury via its classic coupling to Gai-mediated AC inhibition.

Discussion/Conclusions

Nicotine can negate the cardioprotective effects of α2AR agonists against oxidative injury, which may have important implications for patients treated with this class of drugs that are chronic tobacco smokers.

Pannexin 1 Modulates Angiogenic Activities of Human Endothelial Colony-Forming Cells Through IGF-1 Mechanism and Is a Marker of Senescence

BACKGROUND

We examined the role of Panxs (pannexins) in human endothelial progenitor cell (EPC) senescence.

METHODS

Young and replication-induced senescent endothelial colony-forming cells (ECFCs) derived from human circulating EPCs were used to examine cellular activities and senescence-associated indicators after transfection of short interference RNA specific to Panx1 or lentivirus-mediated Panx1 overexpression. Hind limb ischemia mice were used as in vivo angiogenesis model. Protein and phospho-kinase arrays were used to determine underlying mechanisms.

RESULTS

Panx1 was the predominant Panx isoform in human ECFCs and upregulated in both replication-induced senescent ECFCs and circulating EPCs from aged mice and humans. Cellular activities of the young ECFCs were enhanced by Panx1 downregulation but attenuated by its upregulation. In addition, reduction of Panx1 in the senescent ECFCs could rejuvenate cellular activities with reduced senescence-associated indicators, including senescence-associated β-galactosidase activity, p16INK4a (cyclin-dependent kinase inhibitor 2A), p21 (cyclin-dependent kinase inhibitor 1), acetyl-p53 (tumor protein P53), and phospho-histone H2A.X (histone family member X). In mouse ischemic hind limbs injected senescent ECFCs, blood perfusion ratio, salvaged limb outcome, and capillary density were all improved by Panx1 knockdown. IGF-1 (insulin-like growth factor 1) was significantly increased in the supernatant from senescent ECFCs after Panx1 knockdown. The enhanced activities and paracrine effects of Panx1 knockdown senescent ECFCs were completely inhibited by anti-IGF-1 antibodies. FAK (focal adhesion kinase), ERK (extracellular signal-regulated kinase), and STAT3 (signal transducer and activator of transcription 3) were activated in senescent ECFCs with Panx1 knockdown, in which the intracellular calcium level was reduced, and the activation was inhibited by supplemented calcium. The increased IGF-1 in Panx1-knockdown ECFCs was abrogated, respectively, by inhibitors of FAK (PF562271), ERK (U0126), and STAT3 (NSC74859) and supplemented calcium.

CONCLUSIONS

Panx1 expression is upregulated in human ECFCs/EPCs with replication-induced senescence and during aging. Angiogenic potential of senescent ECFCs is improved by Panx1 reduction through increased IGF-1 production via activation of the FAK-ERK axis following calcium influx reduction. Our findings provide new strategies to evaluate EPC activities and rejuvenate senescent EPCs for therapeutic angiogenesis.

Scoping Review on ADCY5-Related Movement Disorders

Background

Adenylyl cyclase 5 (ADCY5)-related movement disorder (ADCY5-RMD) is a rare, childhood-onset disease resulting from pathogenic variants in the ADCY5 gene. The clinical features, diagnostic options, natural history, and treatments for this disease are poorly characterized and have never been established through a structured approach.

Objective

This scoping review attempts to summarize all available clinical literature on ADCY5-RMD.

Methods

Eighty-seven articles were selected for inclusion in this scoping review. The majority of articles identified were case reports or case series.

Results

These articles demonstrate that patients with ADCY5-RMD suffer from permanent and/ or paroxysmal hyperkinetic movements. The paroxysmal episodes can be worsened by environmental triggers, in particular the sleep-wake transition phase in the early morning. Occurrence of nocturnal paroxysmal dyskinesias and perioral twitches are highly suggestive of the diagnosis when present. In the majority of patients intellectual capacity is preserved. ADCY5-RMD is considered a non-progressive disorder, with inter-individual variations in evolution with aging. Somatic mosaicism, mode of inheritance and the location of the mutation within the protein can influence phenotype.

Conclusions

The current evidence for therapeutic options for ADCY5-RMD is limited: caffeine, benzodiazepines and deep brain stimulation have been consistently reported to be useful in case reports and case series.

Expression and functions of adenylyl cyclases in the CNS

Adenylyl cyclases (ADCYs), by generating second messenger cAMP, play important roles in various cellular processes. Their expression, regulation and functions in the CNS, however, remain largely unknown. In this review, we first introduce the classification and structure of ADCYs, followed by a discussion of the regulation of mammalian ADCYs (ADCY1-10). Next, the expression and function of each mammalian ADCY isoform are summarized in a region/cell-specific manner. Furthermore, the effects of GPCR-ADCY signaling on blood-brain barrier (BBB) integrity are reviewed. Last, current challenges and future directions are discussed. We aim to provide a succinct review on ADCYs to foster new research in the future.

Whole Transcriptome Mapping Identifies an Immune- and Metabolism-Related Non-coding RNA Landscape Remodeled by Mechanical Stress in IL-1β-Induced Rat OA-like Chondrocytes

Background: Osteoarthritis (OA) is a common degenerative joint disease. The aims of this study are to explore the effects of mechanical stress on whole transcriptome landscape and to identify a non-coding transcriptome signature of mechanical stress.

Methods: Next-generation RNA sequencing (RNA-seq) was performed on IL-1β-induced OA-like chondrocytes stimulated by mechanical stress. Integrated bioinformatics analysis was performed and further verified by experimental validations.

Results: A total of 5,022 differentially expressed mRNAs (DEMs), 88 differentially expressed miRNAs (DEMIs), 1,259 differentially expressed lncRNAs (DELs), and 393 differentially expressed circRNAs (DECs) were identified as the transcriptome response to mechanical stress. The functional annotation of the DEMs revealed the effects of mechanical stress on chondrocyte biology, ranging from cell fate, metabolism, and motility to endocrine, immune response, and signaling transduction. Among the DELs, ∼92.6% were identified as the novel lncRNAs. According to the co-expressing DEMs potentially regulated by the responsive DELs, we found that these DELs were involved in the modification of immune and metabolism. Moreover, immune- and metabolism-relevant DELs exhibited a notable involvement in the competing endogenous RNA (ceRNA) regulation networks. Silencing lncRNA TCONS_00029778 attenuated cellular senescence induced by mechanical stress. Moreover, the expression of Cd80 was elevated by mechanical stress, which was rescued by silencing TCONS_00029778.

Conclusion: The transcriptome landscape of IL-1β-induced OA-like chondrocytes was remarkably remodeled by mechanical stress. This study identified an immune- and metabolism-related ncRNA transcriptome signature responsive to mechanical stress and provides an insight of ncRNAs into chondrocyte biology and OA.

An osteoarthritis subtype characterized by synovial lipid metabolism disorder and fibroblast-like synoviocyte dysfunction

Background

The heterogeneity of osteoarthritis (OA) significantly limits the effectiveness of pharmacological treatments in an unselected patient population. In this context, the identification of OA subtypes is meaningful for the development of therapies that target specific types of OA pathogenesis.

Methods

Expression array profiles of 70 OA and 36 control synovial samples were extracted from the GEO database. Unsupervised consensus clustering was performed based on the most variable genes to identify OA subclusters. Next, Joint samples from OA patients were obtained. We divided the OA patient into two subpopulations according to synovial ADCY7 levels. Synovium and cartilage samples from different OA subpopulations were evaluated. In addition, we established a high-fat diet (HFD)-induced rat OA model. We evaluated OA progression, lipid metabolism, synovitis and fibroblast-like synoviocytes (FLS) function in this HFD-induced OA model.

Results

70 OA patients were categorized into three distinct subclusters. We noted that one subcluster was characterized by synovial lipid metabolism disorder GO terms. We further identified the most noticeable KEGG pathway “Regulation of lipolysis in adipocytes” in this subcluster as well as the most significantly differentially expressed gene, ADCY7. We found that the ADCY7 high expressing group (32.6%) exhibited features of synovial inflammatory lipolysis epithelial-mesenchymal transition (EMT) tendency, as well as faster join space narrowing. The HFD induced OA-like degeneration in rat joints. We observed similar synovial inflammatory lipolysis and EMT in FLS, characterized by higher proliferative and invasive activity and elevated proinflammatory and procatabolic properties. ADCY7 was highly expressed in the synovium of the HFD-OA model rats and the inhibition of ADCY7 effectively attenuated these HFD-induced degenerative changes as well as synovial inflammatory lipolysis and FLS dysfunction. In HFD-FLSs, ADCY7 promoted the phosphorylation of PKA as well as its downstream lipid droplet-associated protein PLIN1 and hormone-sensitive lipase (HSL). The inhibition of PKA largely alleviated ADCY7-mediated HFD-FLS dysfunction.

Conclusions

We described a synovial EMT and lipid metabolism disorder in the pathogenesis of OA. This novel mechanism may represent a currently undefined OA subtype. ADCY7 is a potential molecular marker of this pathomechanism.

The Translational potential of this article

Utilizing synovial samples from OA patients, we identified a subpopulation with high ADCY7 expression. This may represent a currently undefined OA subtype and explain the clinical phenomenon of more severe synovial inflammation in obese OA patients. In addition, we established an HFD-induced OA rat model and found an upregulation of ADCY7 in the synovium. We confirmed that the inhibition of ADCY7 could effectively attenuate HFD-induced degenerative changes as well as the inflammatory lipolysis and FLS dysfunction observed in the rat model. This suggests that ADCY7 and its downstream pathways are potential pharmacological targets for treating this lipid-metabolism-disorder-related OA mechanism.

Vidarabine, an anti-herpes agent, prevents occlusal-disharmony-induced cardiac dysfunction in mice

We recently reported a positive relationship between occlusal disharmony and cardiovascular disease via activation of β-adrenergic signaling in mice. Furthermore, inhibition of type 5 adenylyl cyclase (AC5), a major cardiac subtype in adults, protects the heart against oxidative stress. Here, we examined the role of AC5 in the development of occlusal-disharmony-induced cardiovascular disease in bite-opening (BO) mice, prepared by cementing a suitable appliance onto the mandibular incisor. We first examined the effects of BO treatment on cardiac function in mice treated or not treated for 2 weeks with vidarabine, which we previously identified as an inhibitor of cardiac AC. Cardiac function was significantly decreased in the BO group compared to the control group, but vidarabine ameliorated the dysfunction. Cardiac fibrosis, myocyte apoptosis and myocyte oxidative DNA damage were significantly increased in the BO group, but vidarabine blocked these changes. The BO-induced cardiac dysfunction was associated with increased phospholamban phosphorylation at threonine-17 and serine-16, as well as increased activation of the Ca2+-calmodulin-dependent protein kinase II/receptor-interacting protein 3 signaling pathway. These data suggest that AC5 inhibition with vidarabine might be a new therapeutic approach for the treatment of cardiovascular disease associated with occlusal disharmony.

Clozapine Long-Term Treatment Might Reduce Epigenetic Age Through Hypomethylation of Longevity Regulatory Pathways Genes

Long-term studies have shown significantly lower mortality rates in patients with continuous clozapine (CLZ) treatment than other antipsychotics. We aimed to evaluate epigenetic age and DNA methylome differences between CLZ-treated patients and those without psychopharmacological treatment. The DNA methylome was analyzed using the Infinium MethylationEPIC BeadChip in 31 CLZ-treated patients with psychotic disorders and 56 patients with psychiatric disorders naive to psychopharmacological treatment. Delta age (Δage) was calculated as the difference between predicted epigenetic age and chronological age. CLZ-treated patients were stratified by sex, age, and years of treatment. Differential methylation sites between both groups were determined using linear regression models. The Δage in CLZ-treated patients was on average lower compared with drug-naive patients for the three clocks analyzed; however, after data-stratification, this difference remained only in male patients. Additional differences were observed in Hannum and Horvath clocks when comparing chronological age and years of CLZ treatment. We identified 44,716 differentially methylated sites, of which 87.7% were hypomethylated in CLZ-treated patients, and enriched in the longevity pathway genes. Moreover, by protein-protein interaction, AMPK and insulin signaling pathways were found enriched. CLZ could promote a lower Δage in individuals with long-term treatment and modify the DNA methylome of the longevity-regulating pathways genes.

Physiological Roles of Mammalian Transmembrane Adenylyl Cyclase Isoforms

Adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. Mammals possess nine isoforms of transmembrane ACs, dubbed AC1-9, that serve as major effector enzymes of G protein-coupled receptors. The transmembrane ACs display varying expression patterns across tissues, giving potential for them having a wide array of physiologic roles. Cells express multiple AC isoforms, implying that ACs have redundant functions. Furthermore, all transmembrane ACs are activated by Gα_s so it was long assumed that all ACs are activated by Gα_s-coupled GPCRs. AC isoforms partition to different microdomains of the plasma membrane and form prearranged signaling complexes with specific GPCRs that contribute to cAMP signaling compartments. This compartmentation allows for a diversity of cellular and physiological responses by enabling unique signaling events to be triggered by different pools of cAMP. Isoform specific pharmacological activators or inhibitors are lacking for most ACs, making knockdown and overexpression the primary tools for examining the physiological roles of a given isoform. Much progress has been made in understanding the physiological effects mediated through individual transmembrane ACs. GPCR-AC-cAMP signaling pathways play significant roles in regulating functions of every cell and tissue, so understanding each AC isoform's role holds potential for uncovering new approaches for treating a vast array of pathophysiological conditions.

Redox Regulation of Lipid Mobilization in Adipose Tissues

Lipid mobilization in adipose tissues, which includes lipogenesis and lipolysis, is a paramount process in regulating systemic energy metabolism. Reactive oxygen and nitrogen species (ROS and RNS) are byproducts of cellular metabolism that exert signaling functions in several cellular processes, including lipolysis and lipogenesis. During lipolysis, the adipose tissue generates ROS and RNS and thus requires a robust antioxidant response to maintain tight regulation of redox signaling. This review will discuss the production of ROS and RNS within the adipose tissue, their role in regulating lipolysis and lipogenesis, and the implications of antioxidants on lipid mobilization.

An Update on the Phenotype, Genotype and Neurobiology of ADCY5-Related Disease

Adenylyl cyclase 5 (ADCY5)-related phenotypes comprise an expanding disease continuum, but much remains to be understood about the underlying pathogenic mechanisms of the disease. ADCY5-related disease comprises a spectrum of hyperkinetic disorders involving chorea, myoclonus, and/or dystonia, often with paroxysmal exacerbations. Hypotonia, developmental delay, and intellectual disability may be present. The causative gene encodes adenylyl cyclase, the enzyme responsible for the conversion of adenosine triphosphate (ATP) to cyclic adenosine-3',5'-monophosphate (cAMP). cAMP is a second messenger that exerts a wide variety of effects via several intracellular signaling pathways. ADCY5 is the most commonly expressed isoform of adenylyl cyclase in medium spiny neurons (MSNs) of the striatum, and it integrates and controls dopaminergic signaling. Through cAMP pathway, ADCY5 is a key regulator of the cortical and thalamic signaling that control initiation of voluntary movements and prevention of involuntary movements. Gain-of-function mutations in ADCY5 have been recently linked to a rare genetic disorder called ADCY5-related dyskinesia, where dysregulation of the cAMP pathway leads to reduced inhibitory activity and involuntary hyperkinetic movements. Here, we present an update on the neurobiology of ADCY5, together with a detailed overview of the reported clinical phenotypes and genotypes. Although a range of therapeutic approaches has been trialed, there are currently no disease-modifying treatments. Improved in vitro and in vivo laboratory models will no doubt increase our understanding of the pathogenesis of this rare genetic movement disorder, which will improve diagnosis, and also facilitate the development of precision medicine approaches for this, and other forms of hyperkinesia. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Compartmentalized Signaling in Aging and Neurodegeneration

The cyclic AMP (cAMP) signalling cascade is necessary for cell homeostasis and plays important roles in many processes. This is particularly relevant during ageing and age-related diseases, where drastic changes, generally decreases, in cAMP levels have been associated with the progressive decline in overall cell function and, eventually, the loss of cellular integrity. The functional relevance of reduced cAMP is clearly supported by the finding that increases in cAMP levels can reverse some of the effects of ageing. Nevertheless, despite these observations, the molecular mechanisms underlying the dysregulation of cAMP signalling in ageing are not well understood. Compartmentalization is widely accepted as the modality through which cAMP achieves its functional specificity; therefore, it is important to understand whether and how this mechanism is affected during ageing and to define which is its contribution to this process. Several animal models demonstrate the importance of specific cAMP signalling components in ageing, however, how age-related changes in each of these elements affect the compartmentalization of the cAMP pathway is largely unknown. In this review, we explore the connection of single components of the cAMP signalling cascade to ageing and age-related diseases whilst elaborating the literature in the context of cAMP signalling compartmentalization.

Pathological Cardiopulmonary Evaluation of Rats Chronically Exposed to Traffic-Related Air Pollution

BACKGROUND

Traffic-related air pollution (TRAP) is made up of complex mixtures of particulate matter, gases and volatile compounds. However, the effects of TRAP on the cardiopulmonary system in most animal studies have been tested using acute exposure to singular pollutants. The cardiopulmonary effects and molecular mechanisms in animals that are chronically exposed to unmodified air pollution as a whole have yet to be studied. Additionally, sex-dependent toxicity of TRAP exposure has rarely been evaluated.

OBJECTIVES

This study sought to assess the cardiopulmonary effect of chronic exposure to unmodified, real-world TRAP in both female and male rats.

METHODS

Four-week-old male and female rats were exposed to TRAP or filtered air for 14 months in a novel facility drawing air from a major freeway tunnel system in Northern California. Inflammation and oxidative stress markers were examined in the lung, heart, spleen, and plasma, and TRAP deposits were quantified in the lungs of both male and female rats.

RESULTS

Elemental analysis showed higher levels of eight elements in the female lungs and one element in the male lungs. Expression of genes related to fibrosis, aging, oxidative stress, and inflammation were higher in the rat hearts exposed to TRAP, with female rats being more susceptible than males. Enhanced collagen accumulation was found only in the TRAP-exposed female hearts. Plasma cytokine secretion was higher in both female and male rats, but inflammatory macrophages were higher only in TRAP-exposed male spleens.

DISCUSSION

Our results in rats suggest pathological consequences from chronic TRAP exposure, including sex differences indicating females may be more susceptible to TRAP-induced cardiac fibrosis. https://doi.org/10.1289/EHP7045.

Healthful aging mediated by inhibition of oxidative stress

The progressive increase in lifespan over the past century carries with it some adversity related to the accompanying burden of debilitating diseases prevalent in the older population. This review focuses on oxidative stress as a major mechanism limiting longevity in general, and healthful aging, in particular. Accordingly, the first goal of this review is to discuss the role of oxidative stress in limiting longevity, and compare healthful aging and its mechanisms in different longevity models. Secondly, we discuss common signaling pathways involved in protection against oxidative stress in aging and in the associated diseases of aging, e.g., neurological, cardiovascular and metabolic diseases, and cancer. Much of the literature has focused on murine models of longevity, which will be discussed first, followed by a comparison with human models of longevity and their relationship to oxidative stress protection. Finally, we discuss the extent to which the different longevity models exhibit the healthful aging features through physiological protective mechanisms related to exercise tolerance and increased β-adrenergic signaling and also protection against diabetes and other metabolic diseases, obesity, cancer, neurological diseases, aging-induced cardiomyopathy, cardiac stress and osteoporosis.

Transcriptomic Analysis of Human Mesenchymal Stem Cell Therapy in Incontinent Rat Injured Urethra

Periurethral human mesenchymal stem cell (hMSC) injections are associated with functional improvement in animal models of postpartum stress urinary incontinence (SUI). However, limited data exist on the role of hMSCs in modulating gene expression in tissue repair after urethral injury. To this end, we quantified temporal gene expression modulation in hMSCs, and in injured rat urethral tissue, using RNA-seq in an animal model of SUI, over a 3-day period following urethral injury, and local hMSC injection. We injected PKH fluorescent-labeled hMSC into the periurethral space of rats following a 4 h vaginal distention (VD) (three rats per time point). Control rats underwent VD injury only, and all animals were euthanized at 12, 24, 36, 72 h postinjury. Rat urethral and vaginal tissues were frozen and sectioned. Fluorescent labeled hMSCs were distinguished from adjacent, unlabeled rat urethral tissue. RNA was prepared from hMSCs and urethral tissue obtained by laser dissection of frozen tissue sections and sequenced on an Illumina HiSeq 2500. Differentially expressed genes (DEGs) over 72 h were evaluated using a two-group t-test (p < 0.05). Our transcriptional analyses identified candidate genes involved in tissue injury that were broadly sorted by injury and exposure to hMSC throughout the first 72 h of acute phase of injury. DEGs in treated urethra, compared with untreated urethra, were functionally associated with tissue repair, angiogenesis, neurogenesis, and oxidative stress suppression. DEGs included a variety of cytokines, extracellular matrix stabilization and regeneration genes, cytokine signaling modification, cell cycle regulation, muscle differentiation, and stabilization. Moreover, our results revealed DEG changes in hMSCs (PKH-labeled) harvested from injured urethra. The expressions are related to DNA damage repair, transcription activation, stem cell regulation, cell survival, apoptosis, self-renewal, cell proliferation, migration, and injury response. Impact statement Stress urinary incontinence (SUI) affects nearly half of women over 40, resulting in reduced quality of life and increased health care cost. Development of SUI is multifactorial and strongly associated with vaginal delivery. While stem cell therapy in animal models of SUI and limited preliminary clinical trials demonstrate functional improvement of SUI, the role of stem cell therapy in modulating tissue repair is unclear impeding advanced clinical trials. Our work provides a new understanding of the transcriptional mechanisms with which human mesenchymal stem cells improve acute injury repair thus guiding the development of cell-based therapies for women with nonacute established SUI.

The Role of Vascular Aging in Atherosclerotic Plaque Development and Vulnerability

BACKGROUND

The ongoing demographical shift is leading to an unprecedented aging of the population. As a consequence, the prevalence of age-related diseases, such as atherosclerosis and its thrombotic complications is set to increase in the near future. Endothelial dysfunction and vascular stiffening characterize arterial aging and set the stage for the development of cardiovascular diseases. Atherosclerotic plaques evolve over time, the extent to which these changes might affect their stability and predispose to sudden complications remains to be determined. Recent advances in imaging technology will allow for longitudinal prospective studies following the progression of plaque burden aimed at better characterizing changes over time associated with plaque stability or rupture. Oxidative stress and inflammation, firmly established driving forces of age-related CV dysfunction, also play an important role in atherosclerotic plaque destabilization and rupture. Several genes involved in lifespan determination are known regulator of redox cellular balance and pre-clinical evidence underlines their pathophysiological roles in age-related cardiovascular dysfunction and atherosclerosis.

OBJECTIVE

The aim of this narrative review is to examine the impact of aging on arterial function and atherosclerotic plaque development. Furthermore, we report how molecular mechanisms of vascular aging might regulate age-related plaque modifications and how this may help to identify novel therapeutic targets to attenuate the increased risk of CV disease in elderly people.

Host genotype and exercise exhibit species-level selection for members of the gut bacterial communities in the mouse digestive system

The mammalian gut microbiome can potentially impact host health and disease state. It is known that the mouse-genome, eating-behavior, and exercise-status promotes higher taxonomic rank-level alterations (e.g. family to phyla-level) of the gut microbiota. Here, host genotype or activity status was investigated to determine if selection of individual bacterial species or strains could be discerned within the murine digestive system. For this study, the fecal bacterial community of adenylyl cyclase 5 knock-out (AC5KO, n = 7) mice or their wild-type (WT, n = 10) littermates under exercise or sedentary conditions were profiled by sequencing rRNA operons. AC5KO mice were chosen since this genotype displays enhanced longevity/exercise capacity and protects against cardiovascular/metabolic disease. Profiling of rRNA operons using the Oxford MinION yielded 65,706 2-D sequences (after size selection of 3.7-5.7 kb) which were screened against an NCBI 16S rRNA gene database. These sequences were binned into 1,566 different best BLAST hits (BBHs) and counted for each mouse sample. Non-metric multidimensional scaling (NMDS) of the gut microbial community demonstrated clustering by physical activity (p = 0.001) but not by host genotype. Additionally, sequence similarity and phylogenetic analysis demonstrated that different bacterial species (closely related to Muribaculum intestinale and Parasutterella excrementihominis) inhabit AC5KO or WT mice depending on activity status. Other bacterial species of the gut microbiota did not follow such patterning (e.g. Turicibacter sanguinis and Turicimonas muris). Our results support the need of improved taxonomic resolution for better characterization of bacterial communities to deepen our understanding of the role of the gut microbiome on host health.

Alterations of the Brain Proteome and Gut Microbiota in d-Galactose-Induced Brain-Aging Mice with Krill Oil Supplementation

Brain aging is commonly associated with neurodegenerative disorders, but the ameliorative effect of krill oil and the underlying mechanism remain unclear. In this study, the components of krill oil were measured, and the antiaging effects of krill oil were investigated in mice with d-galactose (d-gal)-induced brain aging via proteomics and gut microbiota analysis. Krill oil treatment decreased the expression of truncated dopamine- and cAMP-regulated phosphoproteins and proteins involved in the calcium signaling pathway. In addition, the concentrations of dopamine were increased in the serum (p < 0.05) and brain (p > 0.05) due to the enhanced expressions of tyrosine-3-monooxygenase and aromatic l-amino acid decarboxylase. Moreover, krill oil alleviated gut microbiota dysbiosis, decreased the abundance of bacteria that consume the precursor tyrosine, and increased the abundance of Lactobacillus spp. and short-chain fatty acid producers. This study revealed the beneficial effect of krill oil against d-gal-induced brain aging and clarified the underlying mechanism through proteomics and gut microbiota analysis.

Targeting pro-senescence mitogen activated protein kinase (Mapk) enzymes with bioactive natural compounds

Aging is a multifactorial universal process characterized by a gradual decrease in physiological and biochemical functions. Given that life expectancy is on the rise, a better understanding of molecular mechanisms of the aging process is necessary in order to develop anti-aging interventions. Uncontrolled cellular senescence promotes persistent inflammation and accelerates the aging process by decreasing tissue renewal, repair and regeneration. Senescence of immune cells, immunesenescence, is another hallmark of aging. Targeting pro-senescent enzymes increases survival and therefore the lifespan. Although the upregulation of Mitogen Activated Protein Kinases (MAPK) enzymes in aging is still controversial, increasing evidence shows that dysregulation of those enzymes are associated with biological processes that contribute to aging such as irreversible senescence. In this manuscript components of the MAPK pathway will be summarized, including extracellular signal-regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38, as well as natural flavonoids, phenolic and diterpenoids with anti-senescence activity that shows positive effects on longevity and MAPK inhibition. Although more studies using additional aging models are needed, we suggest that these selected natural bioactive compounds that regulate MAPK enzymes and reduce senescent cells can be potentially used to improve longevity and prevent/treat age-related diseases.

Knockout of adenylyl cyclase isoform 5 or 6 differentially modifies the β1-adrenoceptor-mediated inotropic response

Although only β₂-adrenergic receptors (βAR) dually couple with stimulatory G protein (G_s) and inhibitory G protein (G_i), inactivation of G_i enhances both β₁AR and β₂AR responsiveness. We hypothesize that G_i restrains spontaneous adenylyl cyclase (AC) activity independent of receptor activation. Subcellular localization of the AC5/6 subtypes varies contributing to the compartmentation of βAR signaling. The primary objectives were to determine: (1) if β₁AR-mediated inotropic responses were dependent upon either AC5 or AC6; (2) if intrinsic G_i inhibition is AC subtype selective and (3) the role of phosphodiesterases (PDE) 3/4 to regulate β₁AR responsiveness. β₁AR-mediated increases in contractile force and cAMP accumulation in cardiomyocytes were measured from wild type, AC5 and AC6 knockout (KO) mice, with or without pertussis toxin (PTX) pretreatment to inactivate G_i and/or after selective inhibition of PDEs 3/4. Noradrenaline potency at β₁ARs was increased in AC6 KO. PDE4 inhibition increased noradrenaline potency in wild type and AC5 KO, but not AC6 KO. PTX increased noradrenaline potency only in wild type but increased the maximal β₁AR response in all mouse strains. PDE3 inhibition increased noradrenaline potency only in AC5 KO that was treated prior with PTX. β₁AR-evoked cAMP accumulation was increased more by PDE4 inhibition than PDE3 inhibition in wild type and AC5 KO that was amplified by G_i inhibition. These data indicate that β₁AR-mediated inotropic responses are not dependent upon either AC5 or AC6 alone. Inactivation of G_i enhanced β₁AR-mediated inotropic responses despite not coupling to G_i, consistent with G_i exerting a tonic receptor independent inhibition upon AC5/6. PDE4 seems the primary regulator of β₁AR signaling through AC6 in wild type. AC6 KO results in a reorganization of β₁AR compartmentation characterized by signaling through AC5 regulated by G_i, PDE3 and PDE4 that maintains normal contractile function.

Impact of Growth Hormone-Related Mutations on Mammalian Aging

Mutations of a single gene can lead to a major increase in longevity in organisms ranging from yeast and worms to insects and mammals. Discovering these mutations (sometimes referred to as “longevity genes”) led to identification of evolutionarily conserved molecular, cellular, and organismal mechanisms of aging. Studies in mice provided evidence for the important role of growth hormone (GH) signaling in mammalian aging. Mice with mutations or gene deletions leading to GH deficiency or GH resistance have reduced body size and delayed maturation, but are healthier and more resistant to stress, age slower, and live longer than their normal (wild type) siblings. Mutations of the same genes in people can provide remarkable protection from age-related disease, but have no consistent impact on lifespan. Ongoing research indicates that genetic defects in GH signaling are linked to extension of healthspan and lifespan via a variety of interlocking mechanism, including improvements in genome and stem cell maintenance, stress resistance, glucose homeostasis, and thermogenesis, along with reductions in the mechanistic target of rapamycin (mTOR) C1 complex signaling and in chronic low grade inflammation.

Combined Therapy With Swimming Exercise and a Diet Supplemented With Diphenyl Diselenide Is Effective Against Age-Related Changes in the Hepatic Metabolism of Rats

Aging is characterized by a widespread loss of homeostasis in biological systems and is accompanied by pathophysiological changes including the liver injury. The aim of the present study was to investigate the effects of the combined therapy with swimming exercise (20 min session, 5 days/week during 4 weeks) and a diet supplemented with 1 ppm of (PhSe)₂ on the hepatic metabolic alterations caused by aging in rats. In this study, male old Wistar rats had an increase in the epididymal fat relative weight, disturbances in the activities of hepatic enzymes associated to the glucose homeostasis, higher hepatic triglyceride content and higher activity of the plasma alanine aminotransferase (ALT), and aspartate aminotransferase (AST). The combined therapy normalized the activities of glucose-6-Pase and tyrosine aminotransferase, gluconeogenic enzymes, increased the hepatic glycogen content and was effective against the increase in the hepatic triglycerides content, without altering the activities of hexoquinase, and citrate synthase. Moreover, the combined therapy normalized the activities of AST and ALT, indicating a hepatoprotective effect. The combined therapy with swimming exercise and a diet supplemented with 1 ppm of (PhSe)₂ contributed to the hepatic glucose homeostasis in old rats. Nevertheless, more studies are needed to investigate the possible mechanisms of action behind these effects. J. Cell. Biochem. 118: 1574-1582, 2017. © 2016 Wiley Periodicals, Inc.

Modulation of Hydrogen Peroxide-Induced Oxidative Stress in Human Neuronal Cells by Thymoquinone-Rich Fraction and Thymoquinone via Transcriptomic Regulation of Antioxidant and Apoptotic Signaling Genes

Nigella sativa Linn. (N. sativa) and its bioactive constituent Thymoquinone (TQ) have demonstrated numerous pharmacological attributes. In the present study, the neuroprotective properties of Thymoquinone-rich fraction (TQRF) and TQ against hydrogen peroxide- (H₂O₂-) induced neurotoxicity in differentiated human SH-SY5Y cells were investigated. TQRF was extracted using supercritical fluid extraction while TQ was acquired commercially, and their effects on H₂O₂ were evaluated using cell viability assay, reactive oxygen species (ROS) assay, morphological observation, and multiplex gene expression. Both TQRF and TQ protected the cells against H₂O₂ by preserving the mitochondrial metabolic enzymes, reducing intracellular ROS levels, preserving morphological architecture, and modulating the expression of genes related to antioxidants (SOD1, SOD2, and catalase) and signaling genes (p53, AKT1, ERK1/2, p38 MAPK, JNK, and NF-κβ). In conclusion, the enhanced efficacy of TQRF over TQ was likely due to the synergism of multiple constituents in TQRF. The efficacy of TQRF was better than that of TQ alone when equal concentrations of TQ in TQRF were compared. In addition, TQRF also showed comparable effects to TQ when the same concentrations were tested. These findings provide further support for the use of TQRF as an alternative to combat oxidative stress insults in neurodegenerative diseases.