Novel modulators of senescence, aging, and longevity: Small non-coding RNAs enter the stage

Circulating small non-coding RNA profiling for identification of older adults with low muscle strength and physical performance: A preliminary study

BACKGROUND

Small non-coding RNAs (ncRNAs) have recently emerged as potential biomarkers of sarcopenia. However, previous studies have rarely explored the association of small ncRNAs with sarcopenic components, especially muscle strength and physical performance. We aimed to examine circulating small ncRNA profiles to detect low muscle strength and physical performance in older adults.

METHODS

Ninety-eight older adults were randomly selected from Korean Frailty and Aging Cohort Study and classified into the "Normal," "Low muscle strength (MS) only," "Low physical performance (PP) only," and "Low MS and PP" groups by Asian Working Group for Sarcopenia 2019 criteria. We used high-throughput sequencing to delineate small ncRNA profiles in plasma. Differentially expressed small ncRNAs were analyzed to reveal distinct patterns based on muscle strength and physical performance status.

RESULTS

In "Low MS and PP" group, 119 miRNAs, 86 piRNAs, 92 snoRNAs, 106 snRNAs, and 15 tRNAs were differentially expressed compared to "Normal" group (p < 0.05). After Benjamini-Hochberg adjustment, 39 miRNAs, 2 piRNAs, 75 snoRNAs, 48 snRNAs, and 15 tRNAs showed differential expression in "Low MS and PP" group compared to than "Normal" group (adjusted p < 0.05). No significant differences were observed in comparisons between the other groups (adjusted p > 0.05).

CONCLUSION

The expression of circulating small ncRNAs were comprehensively characterized, revealing distinct signatures in older adults with both low muscle strength and physical performance compared to normal individuals. Although preliminary, this characterization can advance small ncRNA research on age-related declines in muscle strength and physical performance by providing foundational data for further investigation.

Urgent needs of caregiving in ageing populations with Alzheimer's disease and other chronic conditions: Support our loved ones

The ageing process begins at birth. It is a life-long process, and its exact origins are still unknown. Several hypotheses attempt to describe the normal ageing process, including hormonal imbalance, formation of reactive oxygen species, DNA methylation & DNA damage accumulation, loss of proteostasis, epigenetic alterations, mitochondrial dysfunction, senescence, inflammation, and stem cell depletion. With increased lifespan in elderly individuals, the prevalence of age-related diseases including, cancer, diabetes, obesity, hypertension, Alzheimer's, Alzheimer's disease and related dementias, Parkinson's, and other mental illnesses are increased. These increased age-related illnesses, put tremendous pressure & burden on caregivers, family members, and friends who are living with patients with age-related diseases. As medical needs evolve, the caregiver is expected to experience an increase in duties and challenges, which may result in stress on themselves, and impact their own family life. In the current article, we assess the biological mechanisms of ageing and its effect on body systems, exploring lifestyle and ageing, with a specific focus on age-related disorders. We also discussed the history of caregiving and specific challenges faced by caregivers in the presence of multiple comorbidities. We also assessed innovative approaches to funding caregiving, and efforts to improve the medical system to better organize chronic care efforts, while improving the skill and efficiency of both informal and formal caregivers. We also discussed the role of caregiving in end-of-life care. Our critical analysis strongly suggests that there is an urgent need for caregiving in aged populations and support from local, state, and federal agencies.

Intrinsic and environmental basis of aging: A narrative review

Longevity has been a topic of interest since the beginnings of humanity, yet its aetiology and precise mechanisms remain to be elucidated. Aging is currently viewed as a physiological phenomenon characterized by the gradual degeneration of organic physiology and morphology due to the passage of time where both external and internal stimuli intervene. The influence of intrinsic factors, such as progressive telomere shortening, genome instability due to mutation buildup, the direct or indirect actions of age-related genes, and marked changes in epigenetic, metabolic, and mitochondrial patterns constitute a big part of its underlying endogenous mechanisms. On the other hand, several psychosocial and demographic factors, such as diet, physical activity, smoking, and drinking habits, may have an even more significant impact on shaping the aging process. Consequentially, implementing dietary and exercise patterns has been proposed as the most viable alternative strategy for attenuating the most typical degenerative aging changes, thus increasing the likelihood of prolonging lifespan and achieving successful aging.

Overview of miR-106a Regulatory Roles: from Cancer to Aging

MicroRNAs (miRNAs) comprise a class of non-coding RNA with extensive regulatory functions within cells. MiR-106a is recognized for its super-regulatory roles in vital processes. Hence, the analysis of its expression in association with diseases has attracted considerable attention for molecular diagnosis and drug development. Numerous studies have investigated miR-106 target genes and shown that this miRNA regulates the expression of some critical cell cycle and apoptosis factors, suggesting miR-106a as an ideal diagnostic and prognostic biomarker with therapeutic potential. Furthermore, the reported correlation between miR-106a expression level and cancer drug resistance has demonstrated the complexity of its functions within different tissues. In this study, we have conducted a comprehensive review on the expression levels of miR-106a in various cancers and other diseases, emphasizing its target genes. The promising findings surrounding miR-106a suggest its potential as a valuable biomolecule. However, further validation assessments and overcoming existing limitations are crucial steps before its clinical implementation can be realized.

[Modern approaches to developing a system of valid methods for monitoring individual health and maintaining active longevity]

Life expectancy In Russia in 2023, according to preliminary data, exceeded 73 years, returning to the pre-pandemic level. The increase in life expectancy is associated both with an improvement in the quality of medical care In Russia and with a more responsible attitude towards the health of citizens, which is confirmed by an improvement in the quality of nutrition, a decrease in alcohol consumption and an increase in the number of people involved in sports. At the same time, there are many signs of aging, both cellular and molecular, some of the main ones are genome stability, telomere shortening, epigenetic alterations, impaired proteostasis and nutrient recognition, mitochondrial dysfunction, depletion of the stem cell pool and changes in intercellular interactions, extracellular matrix rigidity, as well as retrotransposon activation and chronic inflammation. For these reasons, in modern healthcare, the tasks of preventing premature aging and treating age-related diseases are becoming priorities.

MATERIAL AND METHODS

In total, at the first stage of work (in 2023), we examined 80 people, whose average age was 59.6±0.7 years. When analyzing and assessing data, the study adopted a division into age groups (WHO). The following indicators were studied: HbA1, fructosamine, HDL cholesterol, LDL cholesterol, insulin, homocysteine, C-peptide, TSH, free T4, prolactin, total testosterone, cortisol, arginine, asymmetric dimethylarginine, leptin, TNF-a, ferritin, interleukin 1 and 6, telomere length, creatinine, uric acid and urea.

RESULTS

As a result of the study, it was revealed that the aging process of the body affects many indicators, while the main markers that changed in men aged 18 to 44 years were total testosterone, leptin and telomere length; aged 44 to 60 years - HbA1, fructosamine, HDL cholesterol, homocysteine, C-peptide, total testosterone, leptin and telomere length; from 60 to 75 years - fructosamine, HDL cholesterol and telomere length and for 75-90 years - HbA1, HDL cholesterol, insulin, total testosterone, leptin and telomere length, interleukin 6 and uric acid. In women aged 18 to 44 years, only an increase in leptin was observed against the background of shortening telomere length; at the age of 44 to 60 years, the main markers that changed were total testosterone, leptin and telomere length; for the age group 60-75 years - indicators of HbA1, homocysteine, C-peptide, prolactin, total testosterone and leptin, interleukin 6 and uric acid, telomere length was shorter by only 2%; in the age group of 75-90 years, the main markers that changed were insulin, total testosterone, leptin, interleukin 6, while the indicators of uric acid, urea and telomere length differed from the reference values by 2-4%. Shortening of telomere length in all age groups, both men and women, indicates the presence of signs of premature aging. In an individual analysis, data were obtained on a more dramatic shortening of telomeres in 16 subjects in the presence of impaired glucose tolerance and insulin secretion, especially in comparison with healthy subjects, which was confirmed by the data of glycated hemoglobin (HbA1c), while, with shortening of telomere length, the HbA1 indicator was significantly higher (6.8±0.5) than in individuals with long telomeres and no chronic pathology (5.1±0.4).

CONCLUSION

A system of highly valid methods and panels of markers has been developed that indicate the presence of aging processes, taking into account gender and age characteristics, which can be used to identify premature aging processes, monitor individual health and maintain active longevity, as well as for the prevention of age-associated diseases.

Unveiling a novel serpinB2/tripeptidyl peptidase II signaling axis during senescence

Tripeptidyl peptidase II (TPPII) degrades N-terminal tripeptides from proteins and peptides. Studies in both human and mice have shown that TPPII deficiency is linked to cellular immune-senescence, lifespan regulation, and the aging process. However, the mechanism of how TPPII participates in these processes is less clear. In this study, we established a chemical probe-based assay and found that while the mRNA and protein levels of TPPII were not altered during senescence, its enzymatic activity was reduced in senescent human fibroblasts. We also showed that elevation of serine protease inhibitor serpinB2 reduced TPPII activity in senescent cells. Moreover, suppression of TPPII led to elevation of lysosomal contents as well as TPPI and -galactosidase activities, suggesting that the lysosome biogenesis is induced to compensate for the reduction of TPPII activity in senescent cells. Together this study discloses a critical role of the serpinB2/TPPII signaling pathway in proteostasis during senescence. Since serpinB2 level can be increased by a variety of cellular stresses, reduction of TPPII activity through activation of serpinB2 might represent a common pathway for cells to respond to different stress conditions.

MicroRNAs, Long Non-Coding RNAs, and Circular RNAs in the Redox Control of Cell Senescence

Cell senescence is critical in diverse aspects of organism life. It is involved in tissue development and homeostasis, as well as in tumor suppression. Consequently, it is tightly integrated with basic physiological processes during life. On the other hand, senescence is gradually being considered as a major contributor of organismal aging and age-related diseases. Increased oxidative stress is one of the main risk factors for cellular damages, and thus a driver of senescence. In fact, there is an intimate link between cell senescence and response to different types of cellular stress. Oxidative stress occurs when the production of reactive oxygen species/reactive nitrogen species (ROS/RNS) is not adequately detoxified by the antioxidant defense systems. Non-coding RNAs are endogenous transcripts that govern gene regulatory networks, thus impacting both physiological and pathological events. Among these molecules, microRNAs, long non-coding RNAs, and more recently circular RNAs are considered crucial mediators of almost all cellular processes, including those implicated in oxidative stress responses. Here, we will describe recent data on the link between ROS/RNS-induced senescence and the current knowledge on the role of non-coding RNAs in the senescence program.

Small Noncoding RNAome Changes During Human Bone Marrow Mesenchymal Stem Cells Senescence In Vitro

Bone marrow mesenchymal stem cells (BMSCs) have been used in stem cell-based therapy for various diseases due to their self-renewing ability and differentiation potential to various types of cells and immunoprivileged properties. However, the proliferation capability and functionality of BMSCs are known to decline with aging, which severely limits the extensive applications of BMSC-based therapies. To date, the exact mechanism involved in the cellular senescence of BMSCs remains unclear. RNA is thought to be the initial molecular form of life on earth. It also acts as a transmitter and important regulator of genetic information expression. There are many kinds of small noncoding RNAs with different functions in cells that regulate important life activity processes in multiple dimensions, including development process, gene expression, genomic stability, and cellular senescence. In this study, a replicative senescence model of hBMSCs was established and the expression changes of small noncoding RNAs during senescence were detected by small RNA high-throughput sequencing analysis and qPCR. Small RNA sequencing results showed that there were significant differences in the expression of 203 miRNAs, 46 piRNAs, 63 snoRNAs, 12 snRNAs, and 7 rasiRNAs. The results of qPCR, which was performed for the verification of the sequencing results, showed that there were significant differences in the expression of 24 miRNAs, 34 piRNAs, 34 snoRNAs, and 2 snRNAs. These findings might provide a novel insight into hBMSC senescence and contribute to the development of new targeting senescence strategies.

SNPs in miRNAs and Target Sequences: Role in Cancer and Diabetes

miRNAs are fascinating molecular players for gene regulation as individual miRNA can control multiple targets and a single target can be regulated by multiple miRNAs. Loss of miRNA regulated gene expression is often reported to be implicated in various human diseases like diabetes and cancer. Recently, geneticists across the world started reporting single nucleotide polymorphism (SNPs) in seed sequences of miRNAs. Similarly, SNPs are also reported in various target sequences of these miRNAs. Both the scenarios lead to dysregulated gene expression which may result in the progression of diseases. In the present paper, we explore SNPs in various miRNAs and their target sequences reported in various human cancers as well as diabetes. Similarly, we also present evidence of these mutations in various other human diseases.

Epigenetic dysregulation in cardiovascular aging and disease

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity for all sexes, racial and ethnic groups. Age, and its associated physiological and pathological consequences, exacerbate CVD incidence and progression, while modulation of biological age with interventions track with cardiovascular health. Despite the strong link between aging and CVD, surprisingly few studies have directly investigated heart failure and vascular dysfunction in aged models and subjects. Nevertheless, strong correlations have been found between heart disease, atherosclerosis, hypertension, fibrosis, and regeneration efficiency with senescent cell burden and its proinflammatory sequelae. In agreement, senotherapeutics have had success in reducing the detrimental effects in experimental models of cardiovascular aging and disease. Aside from senotherapeutics, cellular reprogramming strategies targeting epigenetic enzymes remain an unexplored yet viable option for reversing or delaying CVD. Epigenetic alterations comprising local and global changes in DNA and histone modifications, transcription factor binding, disorganization of the nuclear lamina, and misfolding of the genome are hallmarks of aging. Limited studies in the aging cardiovascular system of murine models or human patient samples have identified strong correlations between the epigenome, age, and senescence. Here, we compile the findings in published studies linking epigenetic changes to CVD and identify clear themes of epigenetic deregulation during aging. Pending direct investigation of these general mechanisms in aged tissues, this review predicts that future work will establish epigenetic rejuvenation as a potent method to delay CVD.

Beneficial Effects of Exogenous Ketogenic Supplements on Aging Processes and Age-Related Neurodegenerative Diseases

Life expectancy of humans has increased continuously up to the present days, but their health status (healthspan) was not enhanced by similar extent. To decrease enormous medical, economical and psychological burden that arise from this discrepancy, improvement of healthspan is needed that leads to delaying both aging processes and development of age-related diseases, thereby extending lifespan. Thus, development of new therapeutic tools to alleviate aging processes and related diseases and to increase life expectancy is a topic of increasing interest. It is widely accepted that ketosis (increased blood ketone body levels, e.g., β-hydroxybutyrate) can generate neuroprotective effects. Ketosis-evoked neuroprotective effects may lead to improvement in health status and delay both aging and the development of related diseases through improving mitochondrial function, antioxidant and anti-inflammatory effects, histone and non-histone acetylation, β-hydroxybutyrylation of histones, modulation of neurotransmitter systems and RNA functions. Administration of exogenous ketogenic supplements was proven to be an effective method to induce and maintain a healthy state of nutritional ketosis. Consequently, exogenous ketogenic supplements, such as ketone salts and ketone esters, may mitigate aging processes, delay the onset of age-associated diseases and extend lifespan through ketosis. The aim of this review is to summarize the main hallmarks of aging processes and certain signaling pathways in association with (putative) beneficial influences of exogenous ketogenic supplements-evoked ketosis on lifespan, aging processes, the most common age-related neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis), as well as impaired learning and memory functions.

Ultrasonic Diagnosis of Intestinal Loop Obstruction After Introducing Loop Syndrome After Subtotal Gastrectomy

In this paper, a graphical diagnosis of intestinal loop obstruction input into the loop syndrome after subtotal gastrectomy based on ultrasound diagnosis is more fluid accumulating in the bridge loop. The pressure in the intestinal loop is constantly rising, causing bile and pancreatic juice excretion disorder, and dilation of intrahepatic and external bile ducts or dilation of pancreatic ducts, which is similar to the anatomical features of low biliary obstruction. For dilated bowel, the expansion of the upstream drainage pipe organ changes in physiological and pathological anatomy pathological bridge loop obstruction. The ultrasound can show good and on the ming stomach ultrasound pictures of patients with loop syndrome after major resection were analyzed. Most patients with hepatic shape changed the left hepatic duct dilatation, and the inner diameter is 4.8 cm and the length is 18.0 cm. The wall of the tube is a multi-layer structure, and fold-like echoes can be seen. The lumen does not pass through the angle between the superior mesenteric artery and the abdominal aorta. Patients with a history of pancreas Whillp or Child type surgery or a history of Roux-en-Y type biliary jejunum have clinical manifestations of bowel obstruction. The ultrasound of their bridge loop obstruction showed a long tubular anechoic dark area in the upper abdomen and dilation of the upstream drainage organ duct.

Voluntary wheel-running exercise attenuates brain aging of rats through activating miR-130a-mediated autophagy

Autophagy is a highly regulated intracellular process for the degradation of protein aggregates and damaged organelles. Recently, autophagy has been implicated in Alzheimer's disease (AD) and aging. Autophagy process is regulated by the recruitment and assembly of several autophagy-related genes (Atgs) such as, Atg7 and LC3, as the highly conserved and important markers involved in the regulation of autophagy. We recently reported the reduced LC3-II/LC3-I ratio, down-regulated ATG7, and increased p62 protein levels in hippocampal tissues of aging rats. MicroRNA-130a (miR-130a) plays a crucial role in physiological and pathological processes, but whether miR-130a affects the autophagy of brain is unknown. We aim to explore the regulatory role of miR-130a on the autophagy and cell senescence of SH-SY5Y, as well as LC3-II/LC3-I ratio, and the expression of p62, ATG7, Ac-p53 and p21 during exercise intervention of aging rats. In this study, miR-130a expression was markedly down-regulated in the hippocampal of aged rats companying with up-regulated expression of Ac-p53 and p21 when compared with young rats. In contrast, voluntary wheel running could up-regulate miR-130a expression; decrease the expression of Ac-p53 and p21 in aging rats. Interestingly, exercise reversed the impaired autophagy resulted from aging possibly by activating AMPK signaling. Moreover, overexpression of miR-130a in d-galactose (D-gal)-induced SH-SY5Y cell senescence model attenuated d-gal-induced impaired autophagy and cell senescence, demonstrated by decreased levels of LC3, Ac-p53, p21 and increased p62, suggesting that voluntary wheel running can alleviate brain aging in natural aging rats by up-regulating miR-130a-mediated autophagy.

MicroRNA-34a-5p Promotes Joint Destruction During Osteoarthritis

Objective

MicroRNA‐34a‐5p (miR‐34a‐5p) expression is elevated in the synovial fluid of patients with late‐stage knee osteoarthritis (OA); however, its exact role and therapeutic potential in OA remain to be fully elucidated. This study was undertaken to examine the role of miR‐34a‐5p in OA pathogenesis.

Methods

Expression of miR‐34a‐5p was determined in joint tissues and human plasma (n = 71). Experiments using miR‐34a‐5p mimic or antisense oligonucleotide (ASO) treatment were performed in human OA chondrocytes, fibroblast‐like synoviocytes (FLS) (n = 7–9), and mouse OA models, including destabilization of the medial meniscus (DMM; n = 22) and the accelerated, more severe model of mice fed a high‐fat diet and subjected to DMM (n = 11). Wild‐type (WT) mice (n = 9) and miR‐34a–knockout (KO) mice (n = 11) were subjected to DMM. Results were expressed as the mean ± SEM and analyzed by t‐test or analysis of variance, with appropriate post hoc tests. P values less than 0.05 were considered significant. RNA sequencing was performed on WT and KO mouse chondrocytes.

Results

Expression of miR‐34a‐5p was significantly increased in the plasma, cartilage, and synovium of patients with late‐stage OA and in the cartilage and synovium of mice subjected to DMM. Plasma miR‐34a‐5p expression was significantly increased in obese patients with late‐stage OA, and in the plasma and knee joints of mice fed a high‐fat diet. In human OA chondrocytes and FLS, miR‐34a‐5p mimic increased key OA pathology markers, while miR‐34a‐5p ASO improved cellular gene expression. Intraarticular miR‐34a‐5p mimic injection induced an OA‐like phenotype. Conversely, miR‐34a‐5p ASO injection imparted cartilage‐protective effects in the DMM and high‐fat diet/DMM models. The miR‐34a–KO mice exhibited protection against DMM‐induced cartilage damage. RNA sequencing of WT and KO chondrocytes revealed a putative miR‐34a‐5p signaling network.

Conclusion

Our findings provide comprehensive evidence of the role and therapeutic potential of miR‐34a‐5p in OA.

Genes and pathways involved in senescence bypass identified by functional genetic screens

Cellular senescence is a state of stable and irreversible cell cycle arrest with active metabolism, that normal cells undergo after a finite number of divisions (Hayflick limit). Senescence can be triggered by intrinsic and/or extrinsic stimuli including telomere shortening at the end of a cell's lifespan (telomere-initiated senescence) and in response to oxidative, genotoxic or oncogenic stresses (stress-induced premature senescence). Several effector mechanisms have been proposed to explain senescence programmes in diploid cells, including the induction of DNA damage responses, a senescence-associated secretory phenotype and epigenetic changes. Senescent cells display senescence-associated-β-galactosidase activity and undergo chromatin remodeling resulting in heterochromatinisation. Senescence is established by the pRb and p53 tumour suppressor networks. Senescence has been detected in in vitro cellular settings and in premalignant, but not malignant lesions in mice and humans expressing mutant oncogenes. Despite oncogene-induced senescence, which is believed to be a cancer initiating barrier and other tumour suppressive mechanisms, benign cancers may still develop into malignancies by bypassing senescence. Here, we summarise the functional genetic screens that have identified genes, uncovered pathways and characterised mechanisms involved in senescence evasion. These include cell cycle regulators and tumour suppressor pathways, DNA damage response pathways, epigenetic regulators, SASP components and noncoding RNAs.

The Epigenetic Link between Polyphenols, Aging and Age-Related Diseases

Aging is a complex process mainly categorized by a decline in tissue, cells and organ function and an increased risk of mortality. Recent studies have provided evidence that suggests a strong association between epigenetic mechanisms throughout an organism’s lifespan and age-related disease progression. Epigenetics is considered an evolving field and regulates the genetic code at several levels. Among these are DNA changes, which include modifications to DNA methylation state, histone changes, which include modifications of methylation, acetylation, ubiquitination and phosphorylation of histones, and non-coding RNA changes. As a result, these epigenetic modifications are vital targets for potential therapeutic interventions against age-related deterioration and disease progression. Dietary polyphenols play a key role in modulating these modifications thereby delaying aging and extending longevity. In this review, we summarize recent advancements linking epigenetics, polyphenols and aging as well as critical findings related to the various dietary polyphenols in different fruits and vegetables. In addition, we cover studies that relate polyphenols and their epigenetic effects to various aging-related diseases such as cardiovascular diseases, neurodegenerative diseases, autoimmune disorders, diabetes, osteoporosis and cancer.

Emerging role of stem cell-derived extracellular microRNAs in age-associated human diseases and in different therapies of longevity

Organismal aging involves the progressive decline in organ function and increased susceptibility to age-associated diseases. This has been associated with the aging of stem cell populations within the body that decreases the capacity of stem cells to self-renew, differentiate, and regenerate damaged tissues and organs. This review aims to explore how aging is associated with the dysregulation of stem cell-derived extracellular vesicles (SCEVs) and their corresponding miRNA cargo (SCEV-miRNAs), which are short non-coding RNAs involved in post-transcriptional regulation of target genes. Recent evidence has suggested that in aging stem cells, SCEV-miRNAs may play a vital role regulating various processes that contribute to aging: cellular senescence, stem cell exhaustion, telomere length, and circadian rhythm. Hence, further clarifying the age-dependent molecular mechanisms through which SCEV-miRNAs exert their downstream effects may inform a greater understanding of the biology of aging, elucidate their role in stem cell function, and identify important targets for future regenerative therapies. Additionally, current studies evaluating therapeutic role of SCEVs and SCEV-miRNAs in treating several age-associated diseases are also discussed.

Nicotinamide mononucleotide (NMN) supplementation promotes anti-aging miRNA expression profile in the aorta of aged mice, predicting epigenetic rejuvenation and anti-atherogenic effects

Understanding molecular mechanisms involved in vascular aging is essential to develop novel interventional strategies for treatment and prevention of age-related vascular pathologies. Recent studies provide critical evidence that vascular aging is characterized by NAD+ depletion. Importantly, in aged mice, restoration of cellular NAD+ levels by treatment with the NAD+ booster nicotinamide mononucleotide (NMN) exerts significant vasoprotective effects, improving endothelium-dependent vasodilation, attenuating oxidative stress, and rescuing age-related changes in gene expression. Strong experimental evidence shows that dysregulation of microRNAs (miRNAs) has a role in vascular aging. The present study was designed to test the hypothesis that age-related NAD+ depletion is causally linked to dysregulation of vascular miRNA expression. A corollary hypothesis is that functional vascular rejuvenation in NMN-treated aged mice is also associated with restoration of a youthful vascular miRNA expression profile. To test these hypotheses, aged (24-month-old) mice were treated with NMN for 2 weeks and miRNA signatures in the aortas were compared to those in aortas obtained from untreated young and aged control mice. We found that protective effects of NMN treatment on vascular function are associated with anti-aging changes in the miRNA expression profile in the aged mouse aorta. The predicted regulatory effects of NMN-induced differentially expressed miRNAs in aged vessels include anti-atherogenic effects and epigenetic rejuvenation. Future studies will uncover the mechanistic role of miRNA gene expression regulatory networks in the anti-aging effects of NAD+ booster treatments and determine the links between miRNAs regulated by NMN and sirtuin activators and miRNAs known to act in the conserved pathways of aging and major aging-related vascular diseases.

Tat-Mediated Induction of miRs-34a & -138 Promotes Astrocytic Activation via Downregulation of SIRT1: Implications for Aging in HAND

Astrocyte activation is a hallmark of HIV infection and aging in the CNS. In chronically infected HIV patients, prolonged activation of astrocytes has been linked to accelerated aging including but not limited to neurocognitive impairment and frailty. The current study addresses the role of HIV protein Tat in inducing a set of small noncoding microRNAs (miRNA) that play critical role in astrogliosis. In our efforts to link astrocyte activation as an indicator of aging, we assessed the brains of both wild type and HIV transgenic rats for the expression of glial fibrillary acidic protein (GFAP). As expected, in the WT animals we observed age-dependent increase in astrogliosis in the older animals compared to the younger group. Interestingly, compared to the young WT group, young HIV Tg rats exhibited higher levels of GFAP in this trend was also observed in the older HIV Tg rats compared to the older WT group. Based on the role of SIRT1 in aging and the regulation of SIRT1 by miRNAs-34a and -138, we next assessed the expression levels of these miRs in the brains of both the young an old WT and HIV Tg rats. While there were no significant differences in the young WT versus the HIV Tg rats, in the older HIV Tg rats there was a significant upregulation in the expression of miRs-34a & -138 in the brains. Furthermore, increased expression of miRs-34a & -138 in the older Tg rats, correlated with a concomitant decrease in their common anti-aging target protein SIRT1, in the brains of these animals. To delineate the mechanism of action we assessed the role of HIV-Tat (present in the Tg rats) in inducing miRs-34a & -138 in both the primary astrocytes and the astrocytoma cell line A172, thereby leading to posttranscriptional suppression of SIRT1 with a concomitant up regulation of NF-kB driven expression of GFAP.

The serine protease inhibitor serpinB2 binds and stabilizes p21 in senescent cells

SerpinB2 is a serine protease inhibitor also known as plasminogen activator inhibitor type 2 (PAI-2). It has been well documented that serpinB2 is an inhibitor of urokinase plasminogen activator (uPA) and tissue plasminogen activator (tPA). Interestingly, serpinB2 levels are increased in senescent cells and serpinB2 is thus considered a senescence biomarker. In this study, by mimicking the elevated levels of serpinB2 in senescent cells, proliferating human fibroblasts were induced into senescence. Senescence induced by serpinB2 did not relate to its extracellular function, as inhibition of serpinB2 secretion, exogenous introduced serpinB2, or a serpinB2 mutant that failed to bind to its extracellular target uPA did not affect senescence. We also showed that serpinB2 is a direct downstream target of p53 that is activated by the DNA damage response pathway. Significantly, serpinB2 bound to and stabilized p21 to mediate senescence in a proteasome-independent manner, indicating that serpinB2 has a direct role in senescence. Thus, this study reveals a unique mechanism by which serpinB2 maintains senescence through stabilization of p21 protein levels.

Molecular and physiological manifestations and measurement of aging in humans

Biological aging is associated with a reduction in the reparative and regenerative potential in tissues and organs. This reduction manifests as a decreased physiological reserve in response to stress (termed homeostenosis) and a time-dependent failure of complex molecular mechanisms that cumulatively create disorder. Aging inevitably occurs with time in all organisms and emerges on a molecular, cellular, organ, and organismal level with genetic, epigenetic, and environmental modulators. Individuals with the same chronological age exhibit differential trajectories of age-related decline, and it follows that we should assess biological age distinctly from chronological age. In this review, we outline mechanisms of aging with attention to well-described molecular and cellular hallmarks and discuss physiological changes of aging at the organ-system level. We suggest methods to measure aging with attention to both molecular biology (e.g., telomere length and epigenetic marks) and physiological function (e.g., lung function and echocardiographic measurements). Finally, we propose a framework to integrate these molecular and physiological data into a composite score that measures biological aging in humans. Understanding the molecular and physiological phenomena that drive the complex and multifactorial processes underlying the variable pace of biological aging in humans will inform how researchers assess and investigate health and disease over the life course. This composite biological age score could be of use to researchers seeking to characterize normal, accelerated, and exceptionally successful aging as well as to assess the effect of interventions aimed at modulating human aging.

Senescence-associated microRNAs target cell cycle regulatory genes in normal human lung fibroblasts

Senescence recapitulates the ageing process at the cell level. A senescent cell stops dividing and exits the cell cycle. MicroRNAs (miRNAs) acting as master regulators of transcription, have been implicated in senescence. In the current study we investigated and compared the expression of miRNAs in young versus senescent human fibroblasts (HDFs), and analysed the role of mRNAs expressed in replicative senescent HFL-1 HDFs. Cell cycle analysis confirmed that HDFs accumulated in G₁/S cell cycle phase. Nanostring analysis of isolated miRNAs from young and senescent HFL-1 showed that a distinct set of 15 miRNAs were significantly up-regulated in senescent cells including hsa-let-7d-5p, hsa-let-7e-5p, hsa-miR-23a-3p, hsa-miR-34a-5p, hsa-miR-122-5p, hsa-miR-125a-3p, hsa-miR-125a-5p, hsa-miR-125b-5p, hsa-miR-181a-5p, hsa-miR-221-3p, hsa-miR-222-3p, hsa-miR-503-5p, hsa-miR-574-3p, hsa-miR-574-5p and hsa-miR-4454. Importantly, pathway analysis of miRNA target genes down-regulated during replicative senescence in a public RNA-seq data set revealed a significant high number of genes regulating cell cycle progression, both G₁/S and G₂/M cell cycle phase transitions and telomere maintenance. The reduced expression of selected miRNA targets, upon replicative and oxidative-stress induced senescence, such as the cell cycle effectors E2F1, CcnE, Cdc6, CcnB1 and Cdc25C was verified at the protein and/or RNA levels. Induction of G1/S cell cycle phase arrest and down-regulation of cell cycle effectors correlated with the up-regulation of miR-221 upon both replicative and oxidative stress-induced senescence. Transient expression of miR-221/222 in HDFs promoted the accumulation of HDFs in G1/S cell cycle phase. We propose that miRNAs up-regulated during replicative senescence may act in concert to induce cell cycle phase arrest and telomere erosion, establishing a senescent phenotype.

The role of epigenetics in renal ageing

An ability to separate natural ageing processes from processes specific to morbidities is required to understand the heterogeneity of age-related organ dysfunction. Mechanistic insight into how epigenetic factors regulate ageing throughout the life course, linked to a decline in renal function with ageing, is already proving to be of value in the analyses of clinical and epidemiological cohorts. Noncoding RNAs provide epigenetic regulatory circuits within the kidney, which reciprocally interact with DNA methylation processes, histone modification and chromatin. These interactions have been demonstrated to reflect the biological age and function of renal allografts. Epigenetic factors control gene expression and activity in response to environmental perturbations. They also have roles in highly conserved signalling pathways that modulate ageing, including the mTOR and insulin/insulin-like growth factor signalling pathways, and regulation of sirtuin activity. Nutrition, the gut microbiota, inflammation and environmental factors, including psychosocial and lifestyle stresses, provide potential mechanistic links between the epigenetic landscape of ageing and renal dysfunction. Approaches to modify the renal epigenome via nutritional intervention, targeting the methylome or targeting chromatin seem eminently feasible, although caution is merited owing to the potential for intergenerational and transgenerational effects.

XIAP-associating factor 1, a transcriptional target of BRD7, contributes to endothelial cell senescence

X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is well known as an antagonist of XIAP-mediated caspase inhibition. Although XAF1 serves as a tumor-suppressor gene, the role of XAF1 in cellular senescence remains unclear. We found that XAF1 expression was increased by genotoxic agents, such as doxorubicin and ionizing radiation in pulmonary microvascular endothelial cells, consequently leading to premature senescence. Conversely, downregulation of XAF1 in premature senescent cells partially overcame endothelial cell senescence. p53 knockdown, but not p16 knockdown, abolished senescence phenotypes caused by XAF1 induction. XAF1 expression was transcriptionally regulated by Bromodomain 7 (BRD7). XAF1 induction with interferon-gamma (IFN-γ) treatment was abrogated by BRD7 knockdown, which resulted in blocking interferon-induced senescence. In lung cancer cells, XAF1 tumor suppressor activity was decreased by BRD7 knockdown, and inhibition of tumor growth by IFN-γ did not appear in BRD7-depleted xenograft tumors. These data suggest that XAF1 is involved in BRD7-associated senescence and plays an important role in the regulation of endothelial senescence through a p53-dependent pathway. Furthermore, regulation of the BRD7/XAF1 system might contribute to tissue or organismal aging and protection against cellular transformation.

Anti-aging pharmacology: Promises and pitfalls

Life expectancy has grown dramatically in modern times. This increase, however, is not accompanied by the same increase in healthspan. Efforts to extend healthspan through pharmacological agents targeting aging-related pathological changes are now in the spotlight of geroscience, the main idea of which is that delaying of aging is far more effective than preventing the particular chronic disorders. Currently, anti-aging pharmacology is a rapidly developing discipline. It is a preventive field of health care, as opposed to conventional medicine which focuses on treating symptoms rather than root causes of illness. A number of pharmacological agents targeting basic aging pathways (i.e., calorie restriction mimetics, autophagy inducers, senolytics etc.) are now under investigation. This review summarizes the literature related to advances, perspectives and challenges in the field of anti-aging pharmacology.

MicroRNA-17-5p: At the Crossroads of Cancer and Aging - A Mini-Review

The miR-17-92 cluster, led by its most prominent member, miR-17-5p, has been identified as the first miRNA with oncogenic potential. Thus, the whole cluster containing miR-17-5p has been termed oncomiR-1. It is strongly expressed in embryonic stem cells and has essential roles in vital processes like cell cycle regulation, proliferation and apoptosis. The importance of miR-17-5p for fundamental biological processes is underscored by the fact that a miR17-deficient mouse is neonatally lethal. Recently, miR-17-5p was identified in the context of aging, since it is comprised in a common signature of miRNAs that is downregulated in several models of aging research. Recently, miR-17-5p turned out to be the first 'longevimiR' in an animal model, extending the lifespan of a transgenic miR-17-5p-overexpressing mouse. Here, we summarize the current status of research on miR-17-5p with emphasis on its role in cellular senescence, aging and cancer, which points to a pleiotropic function of miR-17-5p regulating multiple targets involved in autophagy, cell cycle regulation and apoptosis in a tissue-dependent fashion. In addition, its elevated presence in serum or plasma of a wide range of tumor patients suggests using it as an 'alarmiR', a general indicator of a potential tumor pathology. However, amounts of circulating miR-17-5p of healthy individuals as reference values are still missing, before any miRNA can be classified as such an 'alarmiR'. In conclusion, miR-17-5p is at the crossroads of aging, longevity and cancer and might represent a promising biomarker or even therapeutic tool and target in this context.

Extracellular Vesicles as New Players in Cellular Senescence

Cell senescence is associated with the secretion of many factors, the so-called "senescence-associated secretory phenotype", which may alter tissue microenvironment, stimulating the organism to clean up senescent cells and replace them with newly divided ones. Therefore, although no longer dividing, these cells are still metabolically active and influence the surrounding tissue. Much attention has been recently focused not only on soluble factors released by senescent cells, but also on extracellular vesicles as conveyors of senescence signals outside the cell. Here, we give an overview of the role of extracellular vesicles in biological processes and signaling pathways related to senescence and aging.

IGF-1 deficiency in a critical period early in life influences the vascular aging phenotype in mice by altering miRNA-mediated post-transcriptional gene regulation: implications for the developmental origins of health and disease hypothesis

Epidemiological findings support the concept of Developmental Origins of Health and Disease, suggesting that early-life hormonal influences during a sensitive period of development have a fundamental impact on vascular health later in life. The endocrine changes that occur during development are highly conserved across mammalian species and include dramatic increases in circulating IGF-1 levels during adolescence. The present study was designed to characterize the effect of developmental IGF-1 deficiency on the vascular aging phenotype. To achieve that goal, early-onset endocrine IGF-1 deficiency was induced in mice by knockdown of IGF-1 in the liver using Cre-lox technology (Igf1 ^f/f mice crossed with mice expressing albumin-driven Cre recombinase). This model exhibits low-circulating IGF-1 levels during the peripubertal phase of development, which is critical for the biology of aging. Due to the emergence of miRNAs as important regulators of the vascular aging phenotype, the effect of early-life IGF-1 deficiency on miRNA expression profile in the aorta was examined in animals at 27 months of age. We found that developmental IGF-1 deficiency elicits persisting late-life changes in miRNA expression in the vasculature, which significantly differed from those in mice with adult-onset IGF-1 deficiency (TBG-Cre-AAV8-mediated knockdown of IGF-1 at 5 month of age in Igf1 ^f/f mice). Using a novel computational approach, we identified miRNA target genes that are co-expressed with IGF-1 and associate with aging and vascular pathophysiology. We found that among the predicted targets, the expression of multiple extracellular matrix-related genes, including collagen-encoding genes, were downregulated in mice with developmental IGF-1 deficiency. Collectively, IGF-1 deficiency during a critical period during early in life results in persistent changes in post-transcriptional miRNA-mediated control of genes critical targets for vascular health, which likely contribute to the deleterious late-life cardiovascular effects known to occur with developmental IGF-1 deficiency.

Molecular biomarkers for chronological age in animal ecology

The chronological age of an individual animal predicts many of its biological characteristics, and these in turn influence population-level ecological processes. Animal age information can therefore be valuable in ecological research, but many species have no external features that allow age to be reliably determined. Molecular age biomarkers provide a potential solution to this problem. Research in this area of molecular ecology has so far focused on a limited range of age biomarkers. The most commonly tested molecular age biomarker is change in average telomere length, which predicts age well in a small number of species and tissues, but performs poorly in many other situations. Epigenetic regulation of gene expression has recently been shown to cause age-related modifications to DNA and to cause changes in abundance of several RNA types throughout animal lifespans. Age biomarkers based on these epigenetic changes, and other new DNA-based assays, have already been applied to model organisms, humans and a limited number of wild animals. There is clear potential to apply these marker types more widely in ecological studies. For many species, these new approaches will produce age estimates where this was previously impractical. They will also enable age information to be gathered in cross-sectional studies and expand the range of demographic characteristics that can be quantified with molecular methods. We describe the range of molecular age biomarkers that have been investigated to date and suggest approaches for developing the newer marker types as age assays in nonmodel animal species.

Identification of Molecular Markers of Delayed Graft Function Based on the Regulation of Biological Ageing

Introduction

Delayed graft function is a prevalent clinical problem in renal transplantation for which there is no objective system to predict occurrence in advance. It can result in a significant increase in the necessity for hospitalisation post-transplant and is a significant risk factor for other post-transplant complications.

Methodology

The importance of microRNAs (miRNAs), a specific subclass of small RNA, have been clearly demonstrated to influence many pathways in health and disease. To investigate the influence of miRNAs on renal allograft performance post-transplant, the expression of a panel of miRNAs in pre-transplant renal biopsies was measured using qPCR. Expression was then related to clinical parameters and outcomes in two independent renal transplant cohorts.

Results

Here we demonstrate, in two independent cohorts of pre-implantation human renal allograft biopsies, that a novel pre-transplant renal performance scoring system (GRPSS), can determine the occurrence of DGF with a high sensitivity (>90%) and specificity (>60%) for donor allografts pre-transplant, using just three senescence associated microRNAs combined with donor age and type of organ donation.

Conclusion

These results demonstrate a relationship between pre-transplant microRNA expression levels, cellular biological ageing pathways and clinical outcomes for renal transplantation. They provide for a simple, rapid quantitative molecular pre-transplant assay to determine post-transplant allograft function and scope for future intervention. Furthermore, these results demonstrate the involvement of senescence pathways in ischaemic injury during the organ transplantation process and an indication of accelerated bio-ageing as a consequence of both warm and cold ischaemia.

Aging Biology in the Kidney

The notion that kidney function declines with age in the general population is well known in the Nephrology community and the average loss of glomerular filtration rate (GFR) about 1ml per year in most longitudinal studies. There is much debate within the community about whether this represents "normal aging" or whether this constitutes a form of renal disease. However this debate turns out, the real question is whether this decline is preventable - can it be modified or slowed? Efforts to find drivers of this decline are still in the very earliest stages, but have shown some promise at elucidating some of the pathologies involved. This article will address both the wider issue of the biology of aging as well as the specific pathologies of the aging kidney.

Use of miRNAs in biofluids as biomarkers in dietary and lifestyle intervention studies

The selection of biomarkers in nutrigenomics needs to reflect subtle changes in homoeostasis representing the relation between nutrition and health, or nutrition and disease. It is believed that noncoding RNAs, such as circulating microRNAs (miRNAs), may represent such a new class of integrative biomarkers. Until now, the most relevant body fluids for miRNA quantification in response to nutrition have not been clearly defined, but recent studies listed in this review indicate that miRNAs from plasma or serum, PBMC and faeces might be relevant biomarkers to quantify the physiological impacts of dietary or lifestyle intervention studies. In addition, a number of recent studies also indicate that miRNAs could permit to monitor the impact of diet on gut microbiota. We also discuss the main preanalytical considerations that are important to take into account before miRNA screening which can affect the reproducibility of the data.

Investigations into cytotoxic effects of the herbal preparation Abnormal Savda Munziq

OBJECTIVE

To evaluate the effects of Abnormal Savda Munziq (ASMq), a traditional herbal medicine, for the prevention and treatment of human diseases, e.g. bowel cancer.

METHODS

The parameters total polyphenol content, cell proliferation and DNA-damage as well as RNA and protein-oxidation were analysed in vitro. Besides, the expressions of miRNA and tumor suppressor genes as well as cellular senescence were evaluated.

RESULTS

ASMq had a high polyphenol content and induced damage to proteins, RNA as well as to DNA, which is correlated with its cytotoxicity. Furthermore ASMq up-regulated the tumor suppressor genes p21, p53 and p16 and down-regulated the micro-RNAs hsa-mir-17 and hsa-mir-106b. In addition cellular growth arrest and SA-β-gal-staining were induced.

CONCLUSION

ASMq has the ability to induce DNA damage and cellular senescence, which are double-edged mechanisms in fighting cancer, as they might also have harmful side effects.

Polymorphisms Falling Within Putative miRNA Target Sites in the 3'UTR Region of SIRT2 and DRD2 Genes Are Correlated With Human Longevity

Many studies have suggested that individual differences in aging phenotypes may be associated to polymorphisms affecting gene regulation. As single-nucleotide polymorphisms (SNPs) in the 3'-untranslated regions (3'UTR) targeted by microRNAs (miRNAs) can alter the strength of miRNA binding (and, consequently, the regulation of target genes), we wondered whether these SNPs (known as miRSNPs) affect the individual chance to become long-lived. Thus, we estimated the effect of miRSNPs falling in the 3'-untranslated regions of 140 aging-related genes on the DNA/miRNA bond. The 24 miRSNPs with the highest difference of binding energy between the two alleles were then investigated for their association with longevity by case-control analysis. Two SNPs,SIRT2-rs45592833 G/T and DRD2-rs6276 A/G, provided a significant association with human longevity, also after correcting for multiple comparisons. For both SNPs, the minor allele was associated with a significantly decreased chance to became long-lived in an allele dose-dependent manner (p= 1.090 × 10(-6)and 1.964 × 10(-4)forSIRT2 and DRD2, respectively). The results indicate that the individual aging phenotype may be affected by the variability of specific miRNA targeted regions, as shown for SIRT2 and DRD2, and may suggest further studies to analyze the variability of gene expression regulation as a modulator of aging phenotypes.

Genome-wide profiling of the microRNA-mRNA regulatory network in skeletal muscle with aging

Skeletal muscle degenerates progressively, losing mass (sarcopenia) over time, which leads to reduced physical ability and often results in secondary diseases such as diabetes and obesity. The regulation of gene expression by microRNAs is a key event in muscle development and disease. To understand genome‐wide changes in microRNAs and mRNAs during muscle aging, we sequenced microRNAs and mRNAs from mouse gastrocnemius muscles at two different ages (6 and 24 months). Thirty‐four microRNAs (15 up‐regulated and 19 down‐regulated) were differentially expressed with age, including the microRNAs miR‐206 and ‐434, which were differentially expressed in aged muscle in previous studies. Interestingly, eight microRNAs in a microRNA cluster at the imprinted Dlk1‐Dio3 locus on chromosome 12 were coordinately down‐regulated. In addition, sixteen novel microRNAs were identified. Integrative analysis of microRNA and mRNA expression revealed that microRNAs may contribute to muscle aging through the positive regulation of transcription, metabolic processes, and kinase activity. Many of the age‐related microRNAs have been implicated in human muscular diseases. We suggest that genome‐wide microRNA profiling will expand our knowledge of microRNA function in the muscle aging process.

The role of microRNAs in cellular senescence and age-related conditions of cartilage and bone

BACKGROUND AND PURPOSE

We reviewed the current state of research on microRNAs in age-related diseases in cartilage and bone.

METHODS

PubMed searches were conducted using separate terms to retrieve articles on (1) the role of microRNAs on aging and tissue degeneration, (2) specific microRNAs that influence cellular and organism senescence, (3) microRNAs in age-related musculoskeletal conditions, and (4) the diagnostic and therapeutic potential of microRNAs in age-related musculoskeletal conditions.

RESULTS

An increasing number of studies have identified microRNAs associated with cellular aging and tissue degeneration. Specifically in regard to frailty, microRNAs have been found to influence the onset and course of age-related musculoskeletal conditions such as osteoporosis, osteoarthritis, and posttraumatic arthritis. Both intracellular and extracellular microRNAs may be suitable to function as diagnostic biomarkers.

INTERPRETATION

The research data currently available suggest that microRNAs play an important role in orchestrating age-related processes and conditions of the musculoskeletal system. Further research may help to improve our understanding of the complexity of these processes at the cellular and extracellular level. The option to develop microRNA biomarkers and novel therapeutic agents for the degenerating diseases of bone and cartilage appears to be promising.

miR-543 and miR-590-3p regulate human mesenchymal stem cell aging via direct targeting of AIMP3/p18

Previously, AIMP3 (aminoacyl-tRNAsynthetase-interacting multifunctional protein-3) was shown to be involved in the macromolecular tRNA synthetase complex or to act as a tumor suppressor. In this study, we report a novel role of AIMP3/p18 in the cellular aging of human mesenchymal stem cells (hMSCs). We found that AIMP3/p18 expression significantly increased in senescent hMSCs and in aged mouse bone marrow-derived MSCs (mBM-MSCs). AIMP3/p18 overexpression is sufficient to induce the cellular senescence phenotypes with compromised clonogenicity and adipogenic differentiation potential. To identify the upstream regulators of AIMP3/p18 during senescence, we screened for potential epigenetic regulators and for miRNAs. We found that the levels of miR-543 and miR-590-3p significantly decreased under senescence-inducing conditions, whereas the AIMP3/p18 protein levels increased. We demonstrate for the first time that miR-543 and miR-590-3p are able to decrease AIMP3/p18 expression levels through direct binding to the AIMP/p18 transcripts, which further compromised the induction of the senescence phenotype. Taken together, our data demonstrate that AIMP3/p18 regulates cellular aging in hMSCs possibly through miR-543 and miR-590-3p.

Circulating MicroRNAs as easy-to-measure aging biomarkers in older breast cancer patients: correlation with chronological age but not with fitness/frailty status

Circulating microRNAs (miRNAs) hold great promise as easily accessible biomarkers for diverse (patho)physiological processes, including aging. We have compared miRNA expression profiles in cell-free blood from older versus young breast cancer patients, in order to identify “aging miRNAs” that can be used in the future to monitor the impact of chemotherapy on the patient’s biological age. First, we assessed 175 miRNAs that may possibly be present in serum/plasma in an exploratory screening in 10 young and 10 older patients. The top-15 ranking miRNAs showing differential expression between young and older subjects were further investigated in an independent cohort consisting of another 10 young and 20 older subjects. Plasma levels of miR-20a-3p, miR-30b-5p, miR106b, miR191 and miR-301a were confirmed to show significant age-related decreases (all p≤0.004). The remaining miRNAs included in the validation study (miR-21, miR-210, miR-320b, miR-378, miR-423-5p, let-7d, miR-140-5p, miR-200c, miR-374a, miR376a) all showed similar trends as observed in the exploratory screening but these differences did not reach statistical significance. Interestingly, the age-associated miRNAs did not show differential expression between fit/healthy and non-fit/frail subjects within the older breast cancer cohort of the validation study and thus merit further investigation as true aging markers that not merely reflect frailty.

Age- and glycemia-related miR-126-3p levels in plasma and endothelial cells

Circulating miR-126-3p levels were determined in 136 healthy subjects (CTRs) aged 20-90 years and 193 patients with type-2 diabetes mellitus (T2DMs) aged 40-80 years, to explore the combined effect of age and glycemic state on miR-126-3p expression. Moreover, intra/extracellular miR-126-3p levels were measured in human endothelial cells (HUVECs) undergoing senescence under normo/hyper-glycemic conditions. Plasma miR-126-3p was significantly higher in the oldest compared with the youngest CTRs ( <45 vs. >75 years; relative expression: 0.27±0.29 vs. 0.48±0.39, p=0.047). Age-based comparison between CTRs and T2DM demonstrated significantly different miR-126-3p levels only in the oldest (0.48±0.39 vs. 0.22±0.23, p<0.005). After multiple adjustments, miR-126-3p levels were seen to be lower in patients with poor glycemic control, compared with age-matched CTRs. The age-related increase in plasma miR-126-3p found in CTRs was paralleled by a 5/6-fold increase in intra/extracellular miR-126-3p in in vitro-cultured HUVECs undergoing senescence. Notably, significant down- regulation of SPRED-1 protein, a validated miR-126-3p target, was found in senescent HUVECs. Moreover, miR-126-3p expression was down-regulated in intermediate-age HUVECs grown in high-glucose medium until senescence. Aging/senescence-associated miR-126-3p up-regulation is likely a senescence-associated compensatory mechanism that is blunted when endothelial cells are exposed to high glucose levels, a phenomenon that probably occurs in vivo in T2DM patients.

Role of microRNAs in the age-related changes in skeletal muscle and diet or exercise interventions to promote healthy aging in humans

Progressive age-related changes in skeletal muscle mass and composition, underpin decreases in muscle function, which can inturn lead to impaired mobility and quality of life in older adults. MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression in skeletal muscle and are associated with aging. Accumulating evidence suggests that miRNAs play an important role in the age-related changes in skeletal muscle mass, composition and function. At the cellular level, miRNAs have been demonstrated to regulate muscle cell proliferation and differentiation. Furthermore, miRNAs are involved in the transitioning of muscle stem cells from a quiescent, to either an activated or senescence state. Evidence from animal and human studies has shown miRNAs are modulated in muscle atrophy and hypertrophy. In addition, miRNAs have been implicated in changes in muscle fiber composition, fat infiltration and insulin resistance. Both exercise and dietary interventions can combat age-related changes in muscle mass, composition and function, which may be mediated by miRNA modulation in skeletal muscle. Circulating miRNA species derived from myogenic cell populations represent potential biomarkers of aging muscle and the molecular responses to exercise or diet interventions, but larger validation studies are required. In future therapeutic approaches targeting miRNAs, either through exercise, diet or drugs may be able to slow down or prevent the age-related changes in skeletal muscle mass, composition, function, hence help maintain mobility and quality of life in old age.

Circulating small noncoding RNAs as biomarkers of aging

Small noncoding RNAs (sncRNAs) mediate a variety of cellular functions in animals and plants. Deep sequencing has made it possible to obtain highly detailed information on the types and abundance of sncRNAs in biological specimens, leading to the discovery that sncRNAs circulate in the blood of humans and mammals. The most abundant types of circulating sncRNAs are microRNAs (miRNAs), 5' transfer RNA (tRNA) halves, and YRNA fragments, with minute amounts of other types that may nevertheless be significant. Of the more abundant circulating sncRNAs only miRNAs have well described functions, but characteristics of the others suggest specific processing and secretion as complexes that protect the RNA from degradation. The properties of circulating sncRNAs are consistent with their serving as signaling molecules, and investigations of circulating miRNAs support the view that they can enter cells and regulate cellular functions. The serum levels of specific sncRNAs change markedly with age, and these changes can be mitigated by calorie restriction (CR), indicating that levels are under physiologic control. The ability of circulating sncRNAs to transmit functions between cells and to regulate a broad spectrum of cellular functions, and the changes in their levels with age, implicate them in the manifestations of aging. Our understanding of the functions of circulating sncRNA, particularly in relation to aging, is currently at a very early stage; results to date suggest that more extensive investigation will yield important insights into mechanisms of aging.

MicroRNA-663 induction upon oxidative stress in cultured human fibroblasts depends on the chronological age of the donor

MicroRNAs, regulators of messenger RNA translation, have been observed to influence many physiological processes, amongst them the process of aging. Higher levels of microRNA-663 (miR-663) have previously been observed in human dermal fibroblasts subject to both replicative and stress-induced senescence compared to early passage cells. Also, higher levels of miR-663 have been found in memory T-cells and in human fibroblasts derived from older donors compared to younger donors. In previous studies we observed that dermal fibroblasts from donors of different chronological and biological age respond differentially to oxidative stress measured by markers of cellular senescence and apoptosis. In the present study we set out to study the association between miR-663 levels and chronological and biological age. Therefore we tested in a total of 92 human dermal fibroblast strains whether the levels of miR-663 in non-stressed and stressed conditions (fibroblasts were treated with 0.6 μM rotenone in stressed conditions) were different in young, middle aged and old donors and whether they were different in middle aged donors dependent on their biological age, as indicated by the propensity for familial longevity. In non-stressed conditions the level of miR-663 did not differ between donors of different age categories and was not dependent on biological age. Levels of miR-663 did not differ dependent on biological age in stressed conditions either. However, for different age categories the level of miR-663 in stressed conditions did differ: the level of miR-663 was higher at higher age categories. Also, the ratio of miR-663 induction upon stress was significantly higher in donors from older age categories. In conclusion, we present evidence for an association of miR-663 upon stress and chronological age.

Slowing the aging process

Research into the aging process is very new. For many years aging was thought to be the natural and inevitable consequence of a life of wear and tear. The idea that aging could be influenced by the genetic code and had a modifiable biologic component is less than 20 years old. During this time, aging has come to be understood as a complex biologic process controlled by signaling pathways and transcription factors. Similar attitudes pervade the field of nephrology. Whether a decline in renal function with age represents normal aging or kidney disease is the subject of much debate.

The biochemistry and cell biology of aging: metabolic regulation through mitochondrial signaling

Cellular and organ metabolism affects organismal lifespan. Aging is characterized by increased risks for metabolic disorders, with age-associated degenerative diseases exhibiting varying degrees of mitochondrial dysfunction. The traditional view of the role of mitochondria generated reactive oxygen species (ROS) in cellular aging, assumed to be causative and simply detrimental for a long time now, is in need of reassessment. While there is little doubt that high levels of ROS are detrimental, mounting evidence points toward a lifespan extension effect exerted by mild to moderate ROS elevation. Dietary caloric restriction, inhibition of insulin-like growth factor-I signaling, and inhibition of the nutrient-sensing mechanistic target of rapamycin are robust longevity-promoting interventions. All of these appear to elicit mitochondrial retrograde signaling processes (defined as signaling from the mitochondria to the rest of the cell, for example, the mitochondrial unfolded protein response, or UPR(mt)). The effects of mitochondrial retrograde signaling may even spread to other cells/tissues in a noncell autonomous manner by yet unidentified signaling mediators. Multiple recent publications support the notion that an evolutionarily conserved, mitochondria-initiated signaling is central to the genetic and epigenetic regulation of cellular aging and organismal lifespan.

Immunosenescence is associated with altered gene expression and epigenetic regulation in primary and secondary immune organs

Deterioration of the immune system (immunosenescence) with age is associated with an increased susceptibility to infection, autoimmune disease and cancer, and reduced responsiveness to vaccination. Immunosenescence entails a reduced supply of naïve T cells from the thymus and increased specialization of peripheral T cell clones. Both thymic involution and peripheral T cell homeostasis are thought to involve cellular senescence. In order to analyze this at the molecular level, we studied gene expression profiles, epigenetic status, and genome stability in the thymus and spleen of 1-, 4-, and 18-month-old Long Evans rats. In the thymus, altered gene expression, DNA and histone H3K9 hypomethylation, increased genome instability, and apoptosis were observed in 18-month-old animals compared to 1- and 4-month-old animals. In the spleen, alterations in gene expression and epigenetic regulation occurred already by the age of 4 months compared to 1 month and persisted in 18-month-old compared to 1-month-old rats. In both organs, these changes were accompanied by the altered composition of resident T cell populations. Our study suggests that both senescence and apoptosis may be involved in altered organ function.

microRNA-141 regulates BMI1 expression and induces senescence in human diploid fibroblasts

Polycomb group protein BMI1 is an important regulator of senescence, aging, and cancer. On one hand, it is overexpressed in cancer cells and is required for self-renewal of stem cells. On the other hand, it is downregulated during senescence and aging. MicroRNAs have emerged as major regulators of almost every gene associated with cancer, aging, and related pathologies. At present, very little is known about the miRNAs that regulate the expression of BMI1. Here, we report that miR-141 posttranscriptionally downregulates BMI1 expression in human diploid fibroblasts (HDFs) via a miR-141 targeting sequence in the 3' untranslated region of BMI1 mRNA. We also show that overexpression of miR-141 induces premature senescence in HDFs via targeting of BMI1 in normal but not in exogenous BMI1-overexpressing HDFs. Induction of premature senescence in HDFs was accompanied by upregulation of p16INK4a, an important downstream target of BMI1 and a major regulator of senescence. Our results suggest that miR-141-based therapies could be developed to treat pathologies where BMI1 is deregulated.

Deep sequencing identifies circulating mouse miRNAs that are functionally implicated in manifestations of aging and responsive to calorie restriction

MicroRNAs (miRNAs) function to modulate gene expression, and through this property they regulate a broad spectrum of cellular processes. They can circulate in blood and thereby mediate cell-to-cell communication. Aging involves changes in many cellular processes that are potentially regulated by miRNAs, and some evidence has implicated circulating miRNAs in the aging process. In order to initiate a comprehensive assessment of the role of circulating miRNAs in aging, we have used deep sequencing to characterize circulating miRNAs in the serum of young mice, old mice, and old mice maintained on calorie restriction (CR). Deep sequencing identifies a set of novel miRNAs, and also accurately measures all known miRNAs present in serum. This analysis demonstrates that the levels of many miRNAs circulating in the mouse are increased with age, and that the increases can be antagonized by CR. The genes targeted by this set of age-modulated miRNAs are predicted to regulate biological processes directly relevant to the manifestations of aging including metabolic changes, and the miRNAs themselves have been linked to diseases associated with old age. This finding implicates circulating miRNAs in the aging process, raising questions about their tissues of origin, their cellular targets, and their functional role in metabolic changes that occur with aging.