MicroRNA in Aging: From Discovery to Biology

Sample-to-answer salivary miRNA testing: New frontiers in point-of-care diagnostic technologies

MicroRNA (miRNA), crucial non-coding RNAs, have emerged as key biomarkers in molecular diagnostics, prognosis, and personalized medicine due to their significant role in gene expression regulation. Salivary miRNA, in particular, stands out for its non-invasive collection method and ease of accessibility, offering promising avenues for the development of point-of-care diagnostics for a spectrum of diseases, including cancer, neurodegenerative disorders, and infectious diseases. Such development promises rapid and precise diagnosis, enabling timely treatment. Despite significant advancements in salivary miRNA-based testing, challenges persist in the quantification, multiplexing, sensitivity, and specificity, particularly for miRNA at low concentrations in complex biological mixtures. This work delves into these challenges, focusing on the development and application of salivary miRNA tests for point-of-care use. We explore the biogenesis of salivary miRNA and analyze their quantitative expression and their disease relevance in cancer, infection, and neurodegenerative disorders. We also examined recent progress in miRNA extraction, amplification, and multiplexed detection methods. This study offers a comprehensive view of the development of salivary miRNA-based point-of-care testing (POCT). Its successful advancement could revolutionize the early detection, monitoring, and management of various conditions, enhancing healthcare outcomes. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices.

MicroRNAs (miRNAs) role in hypertension: pathogenesis and promising therapeutics

Background

MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a crucial role in regulating various cellular processes, including cell proliferation, differentiation, apoptosis, and disease development. Recent studies have highlighted the importance of miRNAs in the development and progression of essential hypertension, a common form of high blood pressure that affects millions of individuals worldwide. The molecular mechanisms by which miRNAs regulate hypertension are complex and multifaceted. MiRNAs target the 3' untranslated regions of mRNA molecules, thereby regulating the synthesis of specific proteins involved in cardiovascular function. For instance, miRNAs are known to regulate the expression of genes involved in blood vessel tone, cardiac function, and inflammation. The growing body of research on miRNAs in hypertension has highlighted their potential as therapeutic targets for managing this condition. Studies have shown that miRNA-based therapies can modulate the expression of key genes involved in hypertension, leading to improvements in blood pressure and cardiovascular function. However, more research is needed to fully understand the mechanisms of miRNA-mediated hypertension and to develop effective therapeutic strategies.

Conclusions

In summary, this review highlights the current understanding of the role of miRNAs in essential hypertension, including their molecular mechanisms and potential therapeutic applications. Further research is needed to fully understand the impact of miRNAs on hypertension and to develop new treatments for this common and debilitating condition.

Hypertrophic cardiomyopathy in MYBPC3 carriers in aging

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, leading to arrhythmias, heart failure, and elevated risk of sudden cardiac death, particularly among the young. This inherited disease is predominantly caused by mutations in sarcomeric genes, among which those in the cardiac myosin binding protein-C3 (MYBPC3) gene are major contributors. HCM associated with MYBPC3 mutations usually presents in the elderly and ranges from asymptomatic to symptomatic forms, affecting numerous cardiac functions and presenting significant health risks with a spectrum of clinical manifestations. Regulation of MYBPC3 expression involves various transcriptional and translational mechanisms, yet the destiny of mutant MYBPC3 mRNA and protein in late-onset HCM remains unclear. Pathogenesis related to MYBPC3 mutations includes nonsense-mediated decay, alternative splicing, and ubiquitin-proteasome system events, leading to allelic imbalance and haploinsufficiency. Aging further exacerbates the severity of HCM in carriers of MYBPC3 mutations. Advancements in high-throughput omics techniques have identified crucial molecular events and regulatory disruptions in cardiomyocytes expressing MYBPC3 variants. This review assesses the pathogenic mechanisms that promote late-onset HCM through the lens of transcriptional, post-transcriptional, and post-translational modulation of MYBPC3, underscoring its significance in HCM across carriers. The review also evaluates the influence of aging on these processes and MYBPC3 levels during HCM pathogenesis in the elderly. While pinpointing targets for novel medical interventions to conserve cardiac function remains challenging, the emergence of personalized omics offers promising avenues for future HCM treatments, particularly for late-onset cases.

Genome-wide RNA polymerase stalling shapes the transcriptome during aging

Gene expression profiling has identified numerous processes altered in aging, but how these changes arise is largely unknown. Here we combined nascent RNA sequencing and RNA polymerase II chromatin immunoprecipitation followed by sequencing to elucidate the underlying mechanisms triggering gene expression changes in wild-type aged mice. We found that in 2-year-old liver, 40% of elongating RNA polymerases are stalled, lowering productive transcription and skewing transcriptional output in a gene-length-dependent fashion. We demonstrate that this transcriptional stress is caused by endogenous DNA damage and explains the majority of gene expression changes in aging in most mainly postmitotic organs, specifically affecting aging hallmark pathways such as nutrient sensing, autophagy, proteostasis, energy metabolism, immune function and cellular stress resilience. Age-related transcriptional stress is evolutionary conserved from nematodes to humans. Thus, accumulation of stochastic endogenous DNA damage during aging deteriorates basal transcription, which establishes the age-related transcriptome and causes dysfunction of key aging hallmark pathways, disclosing how DNA damage functionally underlies major aspects of normal aging.

Epigenetic alterations-The silent indicator for early aging and age-associated health-risks

Aging is the process of gradual physiological deterioration till death and this process perpetually reduce the functionality of an individual. To address the rationale and provide geriatric care, the constant target of geroscience is to identify reliable biomarkers for aging. Over the past decades, diversified advancements in epigenetic studies crescively support the fact that the accumulation of epigenetic changes accompanies the process of aging. A growing number of studies have suggested that alterations occur through three fundamental mechanisms like methylation of DNA, histone protein modification, and production of non-coding microRNAs. Each of these changes occurs silently and provokes alterations in the circumstantial expression of genetic material without altering the underlying gene sequences. The changes in gene expression due to epigenetic alterations are suggested to be the cause of early aging and the onset of age-related health risks. This review would attempt to give an integrated overview of epigenetic changes related to aging and age-associated health risks. This review also discussed epigenomes influencing early aging and factors modulating it. Since epigenetic changes are reversible, early identification of epigenetic markers can be a hope for future geriatric medicine. Finally, this review emphasizes the identification of blood-based epigenetic biomarkers in order to enlighten the future scope for therapeutic intervention to slow down the aging process.

MicroRNAs influence and longevity

Background

MiRNAs play critical roles in the regulation of cellular function, life span, and the aging process. They can affect longevity positively and negatively through different aging pathways.

Main text

MiRNAs are a group of short non-coding RNAs that regulate gene expressions at post-transcriptional levels. The different types of alterations in miRNAs biogenesis, mRNA expressions, and activities of miRNA-protein complexes can affect the regulation of normal post-transcriptional gene process, which may lead to aging, age-related diseases, and an earlier death. It seems that the influence of deregulation of miRNAs on senescence and age-related diseases occurring by targeting aging molecular pathways can be used for diagnosis and prognosis of them. Therefore, the expression and function of miRNAs should be studied more accurately with new applicable and validated experimental tools. However, the current review wishes to highlight simply a connection among miRNAs, senescence and some age-related diseases.

Conclusion

Despite several research indicating the key roles of miRNAs in aging and longevity, further investigations are still needed to elucidate the essential roles of miRNAs in controlling mRNA regulation, cell proliferation, death and/or protection during stress and health problems. Besides, more research on miRNAs will help to identify new targets for alternative strategies regarding effectively screen, treat, and prevent diseases as well as make slow the aging process.

New Roles for MicroRNAs in Old Worms

The use of Caenorhabditis elegans as a model organism in aging research has been integral to our understanding of genes and pathways involved in this process. Several well-conserved signaling pathways that respond to insulin signaling, diet, and assaults to proteostasis have defined roles in controlling lifespan. New evidence shows that microRNAs (miRNAs) play prominent roles in regulating these pathways. In some cases, key aging-related genes have been established as direct targets of specific miRNAs. However, the precise functions of other miRNAs and their protein cofactors in promoting or antagonizing longevity still need to be determined. Here, we highlight recently uncovered roles of miRNAs in common aging pathways, as well as new techniques for the ongoing discovery of miRNA functions in aging C. elegans.

Nuclear and Mitochondrial Genome, Epigenome and Gut Microbiome: Emerging Molecular Biomarkers for Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is currently the second most common neurodegenerative disorder, burdening about 10 million elderly individuals worldwide. The multifactorial nature of PD poses a difficult obstacle for understanding the mechanisms involved in its onset and progression. Currently, diagnosis depends on the appearance of clinical signs, some of which are shared among various neurologic disorders, hindering early diagnosis. There are no effective tools to prevent PD onset, detect the disease in early stages or accurately report the risk of disease progression. Hence, there is an increasing demand for biomarkers that may identify disease onset and progression, as treatment-based medicine may not be the best approach for PD. Over the last few decades, the search for molecular markers to predict susceptibility, aid in accurate diagnosis and evaluate the progress of PD have intensified, but strategies aimed to improve individualized patient care have not yet been established.

CONCLUSIONS

Genomic variation, regulation by epigenomic mechanisms, as well as the influence of the host gut microbiome seem to have a crucial role in the onset and progress of PD, thus are considered potential biomarkers. As such, the human nuclear and mitochondrial genome, epigenome, and the host gut microbiome might be the key elements to the rise of personalized medicine for PD patients.

Transcriptomic Effects of Healthspan-Promoting Dietary Interventions: Current Evidence and Future Directions

Aging is the greatest risk factor most diseases, including cardiovascular disorders, cancers, diabetes, and neurodegeneration, but select nutritional interventions may profoundly reduce the risk for these conditions. These interventions include calorie restriction, intermittent fasting, protein restriction, and reducing intake of certain amino acids. Certain ad libitum diets, including the Mediterranean, Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, and Okinawan diets also promote healthy aging. Evidence indicates that these dietary strategies influence aging and healthspan by acting on the biological "hallmarks of aging" and especially upstream nutrient sensing pathways. Recent advances in "omics" technologies, including RNA-sequencing (transcriptomics), have increased our understanding of how such nutritional interventions may influence gene expression related to these biological mediators of aging, primarily in pre-clinical studies. However, whether these effects are also reflected in the human transcriptome, which may provide insight on other downstream/related cellular processes with aging, is an emerging topic. Broadly, the investigation of how these nutritional interventions influence the transcriptome may provide novel insight into pathways associated with aging, and potential targets to treat age-associated disease and increase healthspan. Therefore, the purpose of this mini review is to summarize what is known about the transcriptomic effects of key dietary/nutritional interventions in both pre-clinical models and humans, address gaps in the literature, and provide insight into future research directions.

Role of the IGF-1 Axis in Overcoming Resistance in Breast Cancer

Over the last two decades, many studies have demonstrated that the insulin-like growth factor-1 (IGF-1) is involved in a number of patho-physiological processes, as well as in the development of different types of solid tumors, including breast cancer (BC). Preclinical and clinical data showed that IGF-1 receptor (R) is overexpressed and hyper-phosphorylated in several subtypes of BCs. The central implications of this pathway in tumor cell proliferation and metastasis make it an important therapeutic target. Moreover, the IGF-1 axis has shown strong interconnection with estrogen regulation and endocrine therapy, suggesting a possible solution to anti-estrogen resistance. IGF-1R might also interfere with other pivotal therapeutic strategies, such as anti HER2 treatments and mTOR inhibitors; several clinical trials are ongoing evaluating the role of IGF-1R inhibition in modulating resistance mechanisms to target therapies. Our aim is to offer an overview of the most recent and significant field of application of IGF-1 inhibitors and relevant therapeutic strategies, weighing their possible future impact on clinical practice.

Mesenchymal stem cell-derived extracellular vesicle-based therapies protect against coupled degeneration of the central nervous and vascular systems in stroke

Stem cell-based treatments have been suggested as promising candidates for stroke. Recently, mesenchymal stem cells (MSCs) have been reported as potential therapeutics for a wide range of diseases. In particular, clinical trial studies have suggested MSCs for stroke therapy. The focus of MSC treatments has been directed towards cell replacement. However, recent research has lately highlighted their paracrine actions. The secretion of extracellular vesicles (EVs) is offered to be the main therapeutic mechanism of MSC therapy. However, EV-based treatments may provide a wider therapeutic window compared to tissue plasminogen activator (tPA), the traditional treatment for stroke. Exosomes are nano-sized EVs secreted by most cell types, and can be isolated from conditioned cell media or body fluids such as plasma, urine, and cerebrospinal fluid (CSF). Exosomes apply their effects through targeting their cargos such as microRNAs (miRs), DNAs, messenger RNAs, and proteins at the host cells, which leads to a shift in the behavior of the recipient cells. It has been indicated that exosomes, in particular their functional cargoes, play a significant role in the coupled pathogenesis and recovery of stroke through affecting the neurovascular unit (NVU). Therefore, it seems that exosomes could be utilized as diagnostic and therapeutic tools in stroke treatment. The miRs are small endogenous non-coding RNA molecules which serve as the main functional cargo of exosomes, and apply their effects as epigenetic regulators. These versatile non-coding RNA molecules are involved in various stages of stroke and affect stroke-related factors. Moreover, the involvement of aging-induced changes to specific miRs profile in stroke further highlights the role of miRs. Thus, miRs could be utilized as diagnostic, prognostic, and therapeutic tools in stroke. In this review, we discuss the roles of stem cells, exosomes, and their application in stroke therapy. We also highlight the usage of miRs as a therapeutic choice in stroke therapy.

Stabilization of telomere by the antioxidant property of polyphenols: Anti-aging potential

Aging is a form of a gradual loss of physiological integrity that results in impaired cellular function and ultimately increased vulnerability to disease and death. This process is a significant risk factor for critical age-related disorders such as cancer, diabetes, cardiovascular disease, and neurological conditions. Several mechanisms contribute to aging, most notably progressive telomeres shortening, which can be counteracted by telomerase enzyme activity and increasing in this enzyme activity associated with partly delaying the onset of aging. Individual behaviors and environmental factors such as nutrition affect the life-span by impact the telomerase activity rate. Healthy eating habits, including antioxidant intakes, such as polyphenols, can have a positive effect on telomere length by this mechanism. In this review, after studying the underlying mechanisms of aging and understanding the relationships between telomeres, telomerase, and aging, it has been attempted to explain the effect of polyphenols on reversing the oxidative stress and aging process.

MicroRNAs Dysregulation and Mitochondrial Dysfunction in Neurodegenerative Diseases

Neurodegenerative diseases are debilitating and currently incurable conditions causing severe cognitive and motor impairments, defined by the progressive deterioration of neuronal structure and function, eventually causing neuronal loss. Understand the molecular and cellular mechanisms underlying these disorders are essential to develop therapeutic approaches. MicroRNAs (miRNAs) are short non-coding RNAs implicated in gene expression regulation at the post-transcriptional level. Moreover, miRNAs are crucial for different processes, including cell growth, signal transmission, apoptosis, cancer and aging-related neurodegenerative diseases. Altered miRNAs levels have been associated with the formation of reactive oxygen species (ROS) and mitochondrial dysfunction. Mitochondrial dysfunction and ROS formation occur in many neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's diseases. The crosstalk existing among oxidative stress, mitochondrial dysfunction and miRNAs dysregulation plays a pivotal role in the onset and progression of neurodegenerative diseases. Based on this evidence, in this review, with a focus on miRNAs and their role in mitochondrial dysfunction in aging-related neurodegenerative diseases, with a focus on their potential as diagnostic biomarkers and therapeutic targets.

Role of microRNAs in neurodegeneration induced by environmental neurotoxicants and aging

The progressive loss of neuronal structure and functions resulting in the death of neurons is considered as neurodegeneration. Environmental toxicants induced degeneration of neurons is accelerated with aging. In adult brains, most of the neurons are post-mitotic, and their loss results in the development of diseases like amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington's disease (HD). Neurodegenerative diseases have several similarities at the sub-cellular and molecular levels, such as synaptic degeneration, oxidative stress, inflammation, and cognitive decline, which are also known in brain aging. Identification of these similarities at the molecular level offers hope for the development of new therapeutics to ameliorate all neurodegenerative diseases simultaneously. Aging is known as the most strongly associated additive factor in the pathogenesis of neurodegenerative diseases. Studies carried out so far identified several genes, which are responsible for selective degeneration of neurons in different neurodegenerative diseases. Countless efforts have been made in identifying therapeutics for neurodegenerative diseases; however, the discovery of effective therapy remains elusive. Findings made in the last two decades identified microRNAs (miRNAs) as the most potent post-transcription regulatory RNA molecule, which can condition protein levels in the cell and tissue-specific manner. Identification of miRNAs, which regulate both neurotoxicant and aging-associated degeneration of brain cells, raises the possibility that roads leading to aging and neurotoxicant induced neurodegeneration cross at some point. Identification of miRNAs, which are common to aging and neurotoxicant induced neurodegeneration, will help in understanding the complex mechanism of neurodegenerative disease development. In the future, the use of natural miRNAs in vivo in therapy will be able to tackle several issues of aging and neurodegeneration. In the present review, we have provided a summary of findings made on the role of miRNAs in neurodegeneration and explored the common link made by miRNAs between aging and neurotoxicants induced neurodegeneration.

MicroRNA-214 modulates the senescence of vascular smooth muscle cells in carotid artery stenosis

Background

MicroRNAs control gene expression by post-transcriptional inhibition. Dysregulation of the expressions of miR-199a/214 cluster has been linked to cardiovascular diseases. This study aimed at identifying potential microRNAs related to vascular senescence.

Methods

Seven candidate microRNAs (miR-19a, −20a, −26b, −106b, − 126, − 214, and − 374) related to cell proliferation were tested for their expressions under CoCl₂-induced hypoxia in vascular smooth muscle cells (VSMCs). After identification of miR-214 as the candidate microRNA, telomere integrity impairment and cell cycle arrest were examined in VSMCs by using miR-214 mimic, AntagomiR, and negative controls. To investigate the clinical significance of miR-214 in vascular diseases, its plasma level from patients with carotid artery stenosis (CAS) was assessed by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).

Results

CoCl₂ treatment for 48 h suppressed cell proliferation and angiogenesis as well as enhanced cell senescence in VSMCs. Besides, miR-214 level was elevated in both intracellular and exosome samples of VSMCs after CoCl₂ treatment. Manipulating miR-214 in VSMCs demonstrated that miR-214 not only inhibited angiogenic and proliferative capacities but also promoted senescence through the suppression of quaking. Additionally, circulating miR-214 level was upregulated in CAS patients with high low-density lipoprotein cholesterol (LDL-C) value.

Conclusion

Our findings suggested that miR-214 plays a role in the modulation of VSMC angiogenesis, proliferation, and senescence with its plasma level being increased in CAS patients with elevated LDL-C value, implying that it may be a vascular senescence marker and a potential therapeutic target for vascular diseases.

Age and poverty status alter the coding and noncoding transcriptome

Emerging evidence indicates that noncoding RNAs play regulatory roles in aging and disease. The functional roles of long noncoding RNAs (lncRNAs) in physiology and disease are not completely understood. Little is known about lncRNAs in the context of human aging and socio-environmental conditions. Microarray profiling of lncRNAs and mRNAs from peripheral blood mononuclear cells from young and old white (n=16) and African American (AA) males (n=16) living above or below poverty from the Healthy Aging in Neighborhoods of Diversity across the Life Span study revealed changes in both lncRNAs and mRNAs with age and poverty status in white males, but not in AA males. We validated lncRNA changes in an expanded cohort (n=40); CTD-3247F14.2, GAS5, H19, TERC and MEG3 changed significantly with age, whereas AK022914,GAS5, KB-1047C11.2, MEG3 and XLOC_003262 changed with poverty. Mitochondrial function and response to DNA damage and stress were pathways enriched in younger individuals. Response to stress, viral infection, and immune signals were pathways enriched in individuals living above poverty. These data show that both human age and a marker of social adversity influence lncRNA expression, which may provide insight about molecular pathways underlying aging and social factors that affect disparities in aging and disease.

Ancestral stress programs sex-specific biological aging trajectories and non-communicable disease risk

The incidence of non-communicable diseases (NCDs) is rising globally but their causes are generally not understood. Here we show that cumulative ancestral stress leads to premature aging and raises NCD risk in a rat population. This longitudinal study revealed that cumulative multigenerational prenatal stress (MPS) across four generations (F0-F3) raises age- and sex-dependent adverse health outcomes in F4 offspring. MPS accelerated biological aging processes and exacerbated sex-specific incidences of respiratory and kidney diseases, inflammatory processes and tumors. Unbiased deep sequencing of frontal cortex revealed that MPS altered expression of microRNAs and their target genes involved in synaptic plasticity, stress regulation, immune function and longevity. Multi-layer top-down deep learning metabolite enrichment analysis of urine markers revealed altered metabolic homeodynamics in MPS males. Thus, peripheral metabolic signatures may provide sensitive biomarkers of stress vulnerability and disease risk. Programming by MPS appears to be a significant determinant of lifetime mental health trajectories, physical wellbeing and vulnerability to NCDs through altered epigenetic regulation.

MicroRNA-34a causes ceramide accumulation and effects insulin signaling pathway by targeting ceramide kinase (CERK) in aging skeletal muscle

Aging skeletal muscle shows perturbations in metabolic functions. MicroRNAs have been shown to play a critical role in aging and metabolic functions of skeletal muscle. MicroRNA-34a (miR-34a) is implicated in the brain and cardiac aging, however, its role in aging muscle is unclear. We analyzed levels of miR-34a, ceramide kinase (CERK) and other insulin signaling molecules in skeletal muscle from old mice. In addition to in vivo model, levels of these molecules were also analyzed in myoblast derived from insulin resistant (IR) humans and C2C12 myoblasts overexpressing mir-34a. Our results show that miR-34a is elevated in the muscles of 2-year-old mice and in the myoblasts of IR humans. Overexpression of miR-34a in C2C12 myoblasts leads to alterations in the insulin signaling pathway, which were rescued by its antagonism. Our analyses revealed that miR-34a targets CERK resulting in ceramide accumulation, activation of PP2A and the pJNK pathway in muscle and C2C12 myoblasts. Also, myostatin (Mstn) levels were increased in 2-year-old mouse muscle and Mstn treatment upregulated miR-34a in C2C12 myoblasts. In addition, miR-34a expression and ceramide levels did not increase during aging in Mstn^-/- mice muscle. In summary, we, therefore, propose that Mstn levels increase in aging muscle and upregulate miR-34a, which inhibits CERK resulting in increased ceramide levels. This ceramide accumulation activates PP2A and pJNK causing hypophosphorylation of AKT and hyperphosphorylation of IRS1 (Ser307), respectively, impairing insulin signaling pathway and eventually inhibiting the sarcolemma localization of GLUT4. These changes would result in reduced glucose uptake and insulin resistance. This study is the first to explain the phenomenon of ceramide accrual and impairment of insulin signaling pathway in aging muscle through a miR-34a based mechanism. In conclusion, our results suggest that Mstn and miR-34a antagonism can help ameliorate ceramide accumulation and loss of insulin sensitivity in aging skeletal muscle.

Cell-free miRNAs as non-invasive biomarkers in breast cancer: Significance in early diagnosis and metastasis prediction

Breast cancer is one of the genetic diseases causing a high mortality among women around the world. Despite the availability of advanced diagnostic tools and treatment strategies, the incidence of breast cancer is increasing every year. This is due to the lack of accurate and reliable biomarkers whose deficiency creates difficulty in early breast cancer recognition, subtypes determination, and metastasis prophecy. Although biomarkers such as ER, PR, Her2, Ki-67, and other genetic platforms e.g. MammaPrint®, Oncotype DX®, Prosigna® or EndoPredict® are available for determination of breast cancer diagnosis and prognosis. However, pertaining to heterogeneous nature, lack of sensitivity, and specificity of these markers, it is still incessant to overcome breast cancer burden. Therefore, a novel biomarker is urgently needed for therapeutic diagnosis and improving prognosis. Lately, it has become more evident that cell-free miRNAs might be useful as good non-invasive biomarkers that are associated with different events in carcinogenesis. For example, some known biomarkers such as miR-21, miR-23a, miR-34a are associated with molecular subtyping and different biomolecular aspects i.e. apoptosis, angiogenesis, metastasis, and miR-1, miR-10b, miR-16 are associated with drug response. Cell-free miRNAs present in human body fluids have proven to be potential biomarkers with significant prognostic and predictive values. Numerous studies have found a distinct expression profile of circulating miRNAs in breast tumour versus non-tumour and in early and advanced-stage, thus implicating its clinical relevance. This review article will highlight the importance of different cell-free miRNAs as a biomarker for early breast cancer detection, subtype classification, and metastasis forecast.

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.

Epigenetic Regulation by Dietary Restriction: Part II

In the first part of our review, we extensively discuss the different variants of dietary restriction (DR) regimens, as well as its corresponding mechanism(s) and subsequent effects. We also provide a detailed analysis of the different epigenetic mechanisms based on current knowledge. We postulate that DR may represent an environmental intervention that can modulate the epigenomic profile of an individual. It is highly plausible that epigenetic regulation by DR may help explain the asymmetric manifestation of DR effects in different individuals. Additionally, epigenetic modifications via DR may lead to epigenetic programming, providing protection against age-associated diseases, which in turn could lead to reduced morbidity and increased lifespan. In the second part of the review, we summarize recent findings that highlight the epigenomic axis of DR, which provides a better understanding of the mechanisms by which its numerous health benefits are achieved.

Rn7SK small nuclear RNA is involved in cellular senescence

Rn7SK is a conserved small nuclear noncoding RNA which its function in aging has not been studied. Recently, we have demonstrated that Rn7SK overexpression reduces cell viability and is significantly downregulated in stem cells, human tumor tissues, and cell lines. In this study, we analyzed the role of Rn7SK on senescence in adipose tissue-derived mesenchymal stem cells (AD-MSCs). For this purpose, Rn7SK expression was downregulated and upregulated via transfection and transduction, respectively, in AD-MSCs and subsequently, various distinct characteristics of senescence including cell viability, proliferation, colony formation, senescence-associated β galactosidase activity, and differentiation potency was analyzed. Our results demonstrated the transient knockdown of Rn7SK in MSCs leads to delayed senescence, while its overexpressions shows opposite effects. When osteogenic differentiation was started, however, they exhibited a greater differentiation potential than the original MSCs, suggesting a potential tool for stem cell-based regenerative medicine.

Immunosenescence: A systems-level overview of immune cell biology and strategies for improving vaccine responses

Immunosenescence contributes to a decreased capacity of the immune system to respond effectively to infections or vaccines in the elderly. The full extent of the biological changes that lead to immunosenescence are unknown, but numerous cell types involved in innate and adaptive immunity exhibit altered phenotypes and function as a result of aging. These manifestations of immunosenescence at the cellular level are mediated by dysregulation at the genetic level, and changes throughout the immune system are, in turn, propagated by numerous cellular interactions. Environmental factors, such as nutrition, also exert significant influence on the immune system during aging. While the mechanisms that govern the onset of immunosenescence are complex, systems biology approaches allow for the identification of individual contributions from each component within the system as a whole. Although there is still much to learn regarding immunosenescence, systems-level studies of vaccine responses have been highly informative and will guide the development of new vaccine candidates, novel adjuvant formulations, and immunotherapeutic drugs to improve vaccine responses among the aging population.

Lack of Association Between Select Circulating miRNAs and Bone Mass, Turnover, and Fractures: Data From the OFELY Cohort

Postmenopausal osteoporosis is characterized by the occurrence of fragility fracture with an increase in morbidity and mortality. Recently, microRNAs (miRNAs) have raised interest as regulators of translational repression, mediating a number of key processes, including bone tissue in both physiological and diseased states. The aim of this study was to examine the serum levels of 32 preselected miRNAs with reported function in bone and their association with osteoporotic fracture. We performed cross-sectional and longitudinal analyses from the OFELY Cohort. Serum levels of the miRNAs were quantified by qRT-PCR in 682 women: 99 premenopausal and 583 postmenopausal women, with 1 and 122 women with prevalent fragility fractures in each group, respectively. We have collected clinical variables (such as age, prevalent, and incident fractures), bone turnover markers (BTMs), BMD by dual X-ray absorptiometry, and bone microarchitecture with HRpQCT. We observed a number of miRNAs to be associated with fragility fractures (prevalent or incident), BTMs, BMD, and microarchitecture. This effect, however, was negated after age adjustment. This may be because age was also strongly associated with the serum levels of the 32 miRNAs (correlation coefficient up to 0.49), confirming previous findings. In conclusion, in a well-characterized prospective cohort with a sizeable sample size, we found no evidence that these 32 preselected miRNAs were not associated with BTMs, BMD, microarchitecture, and or fragility fractures. © 2019 American Society for Bone and Mineral Research.

The p53/miRNAs/Ccna2 pathway serves as a novel regulator of cellular senescence: Complement of the canonical p53/p21 pathway

Aging is a multifactorial process characterized by the progressive deterioration of physiological functions. Among the multiple molecular mechanisms, microRNAs (miRNAs) have increasingly been implicated in the regulation of Aging process. However, the contribution of miRNAs to physiological Aging and the underlying mechanisms remain elusive. We herein performed high-throughput analysis using miRNA and mRNA microarray in the physiological Aging mouse, attempted to deepen into the understanding of the effects of miRNAs on Aging process at the "network" level. The data showed that various p53 responsive miRNAs, including miR-124, miR-34a and miR-29a/b/c, were up-regulated in Aging mouse compared with that in Young mouse. Further investigation unraveled that similar as miR-34a and miR-29, miR-124 significantly promoted cellular senescence. As expected, mRNA microarray and gene co-expression network analysis unveiled that the most down-regulated mRNAs were enriched in the regulatory pathways of cell proliferation. Fascinatingly, among these down-regulated mRNAs, Ccna2 stood out as a common target of several p53 responsive miRNAs (miR-124 and miR-29), which functioned as the antagonist of p21 in cell cycle regulation. Silencing of Ccna2 remarkably triggered the cellular senescence, while Ccna2 overexpression delayed cellular senescence and significantly reversed the senescence-induction effect of miR-124 and miR-29. Moreover, these p53 responsive miRNAs were significantly up-regulated during the senescence process of p21-deficient cells; overexpression of p53 responsive miRNAs or knockdown of Ccna2 evidently accelerated the cellular senescence in the absence of p21. Taken together, our data suggested that the p53/miRNAs/Ccna2 pathway might serve as a novel senescence modulator independent of p53/p21 pathway.

MicroRNAs and the Genetic Nexus of Brain Aging, Neuroinflammation, Neurodegeneration, and Brain Trauma

Aging is a complex and integrated gradual deterioration of cellular activities in specific organs of the body, which is associated with increased mortality. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, neurovascular disorders, and neurodegenerative diseases. There are nine tentative hallmarks of aging. In addition, several of these hallmarks are increasingly being associated with acute brain injury conditions. In this review, we consider the genes and their functional pathways involved in brain aging as a means of developing new strategies for therapies targeted to the neuropathological processes themselves, but also as targets for many age-related brain diseases. A single microRNA (miR), which is a short, non-coding RNA species, has the potential for targeting many genes simultaneously and, like practically all other cellular processes, genes associated with many features of brain aging and injury are regulated by miRs. We highlight how certain miRs can mediate deregulation of genes involved in neuroinflammation, acute neuronal injury and chronic neurodegenerative diseases. Finally, we review the recent progress in the development of effective strategies to block specific miR functions and discuss future approaches with the prediction that anti-miR drugs may soon be used in the clinic.

Epigenetic changes during aging and their reprogramming potential

The aging process results in significant epigenetic changes at all levels of chromatin and DNA organization. These include reduced global heterochromatin, nucleosome remodeling and loss, changes in histone marks, global DNA hypomethylation with CpG island hypermethylation, and the relocalization of chromatin modifying factors. Exactly how and why these changes occur is not fully understood, but evidence that these epigenetic changes affect longevity and may cause aging, is growing. Excitingly, new studies show that age-related epigenetic changes can be reversed with interventions such as cyclic expression of the Yamanaka reprogramming factors. This review presents a summary of epigenetic changes that occur in aging, highlights studies indicating that epigenetic changes may contribute to the aging process and outlines the current state of research into interventions to reprogram age-related epigenetic changes.

Temporal Integrative Analysis of mRNA and microRNAs Expression Profiles and Epigenetic Alterations in Female SAMP8, a Model of Age-Related Cognitive Decline

A growing body of research shows that epigenetic mechanisms are critically involved in normal and pathological aging. The Senescence-Accelerated Mouse Prone 8 (SAMP8) can be considered a useful tool to better understand the dynamics of the global epigenetic landscape during the aging process since its phenotype is not fully explained by genetic factors. Here we investigated dysfunctional age-related transcriptional profiles and epigenetic programming enzymes in the hippocampus of 2- and 9-month-old SAMP8 female mice using the Senescent-Accelerated Resistant 1 (SAMR1) mouse strain as control. SAMP8 mice presented 1,062 genes dysregulated at 2 months of age, and 1,033 genes at 9 months, with 92 genes concurrently dysregulated at both ages compared to age-matched SAMR1. SAMP8 mice showed a significant decrease in global DNA methylation (5-mC) at 2 months while hydroxymethylation (5-hmC) levels were increased in SAMP8 mice at 2 and 9 months of age compared to SAMR1. These changes were accompanied by changes in the expression of several enzymes that regulate 5-mC and methylcytosine oxidation. Acetylated H3 and H4 histone levels were significantly diminished in SAMP8 mice at 2-month-old compared to SAMR1 and altered Histone DeACetylase (HDACs) profiles were detected in both young and old SAMP8 mice. We analyzed 84 different mouse miRNAs known to be altered in neurological diseases or involved in neuronal development. Compared with SAMR1, SAMP8 mice showed 28 and 17 miRNAs differentially expressed at 2 and 9 months of age, respectively; 6 of these miRNAs overlapped at both ages. We used several bioinformatic approaches to integrate our data in mRNA:miRNA regulatory networks and functional predictions for young and aged animals. In sum, our study reveals interplay between epigenetic mechanisms and gene networks that seems to be relevant for the progression toward a pathological aging and provides several potential markers and therapeutic candidates for Alzheimer's Disease (AD) and age-related cognitive impairment.

Loss of miR-83 extends lifespan and affects target gene expression in an age-dependent manner in Caenorhabditis elegans

MicroRNAs (miRNAs) are short non-coding RNAs that are involved in the post-transcriptional regulation of protein-coding genes. miRNAs modulate lifespan and the aging process in a variety of organisms. In this study, we identified a role of miR-83 in regulating lifespan of Caenorhabditis elegans. mir-83 mutants exhibited extended lifespan, and the overexpression of miR-83 was sufficient to decrease the prolonged lifespan of the mutants. We observed upregulation of the expression levels of a set of miR-83 target genes in young mir-83 mutant adults; while different sets of genes were upregulated in older mir-83 mutant adults. In vivo assays showed that miR-83 regulated expression of target genes including din-1, spp-9 and col-178, and we demonstrated that daf-16 and din-1 were required for the extension of lifespan in the mir-83 mutants. The regulation of din-1 by miR-83 during aging resulted in the differential expression of din-1 targets such as gst-4 and gst-10. In daf-2 mutants, the expression level of miR-83 was significantly reduced compared to wild-type animals. We identified a role for miR-83 in modulating lifespan in C. elegans and provided molecular insights into its functional mechanism.

MiR-34a and stroke: Assessment of non-modifiable biological risk factors in cerebral ischemia

Aging of the nervous system, and the occurrence of age-related brain diseases such as stroke, are associated with changes to a variety of cellular processes controlled by many distinct genes. MicroRNAs (miRNAs), short non-coding functional RNAs that can induce translational repression or site-specific cleavage of numerous target mRNAs, have recently emerged as important regulators of cellular senescence, aging, and the response to neurological insult. Here, we focused on the assessment of the role of miR-34a in stroke. We noted increases in miR-34a expression in the blood of stroke patients as well as in blood and brain of mice subjected to experimental stroke. Our methodical genetic manipulation of miR-34a expression substantially impacted stroke-associated preclinical outcomes and we have in vitro evidence that these changes may be driven at least in part by disruptions to blood brain barrier integrity and mitochondrial oxidative phosphorylation in endothelial cells. Finally, aging, independent of brain injury, appears to be associated with shifts in circulating miRNA profiles. Taken together, these data support a role for miRNAs, and specifically miR-34a, in brain aging and the physiological response to age-related neurological insult, and lay the groundwork for future investigation of this novel therapeutic target.

Unique patterns of trimethylation of histone H3 lysine 4 are prone to changes during aging in Caenorhabditis elegans somatic cells

Tri-methylation on histone H3 lysine 4 (H3K4me3) is associated with active gene expression but its regulatory role in transcriptional activation is unclear. Here we used Caenorhabditis elegans to investigate the connection between H3K4me3 and gene expression regulation during aging. We uncovered around 30% of H3K4me3 enriched regions to show significant and reproducible changes with age. We further showed that these age-dynamic H3K4me3 regions largely mark gene-bodies and are acquired during adult stages. We found that these adult-specific age-dynamic H3K4me3 regions are correlated with gene expression changes with age. In contrast, H3K4me3 marking established during developmental stages remained largely stable with age, even when the H3K4me3 associated genes exhibited RNA expression changes during aging. Importantly, the genes associated with changes in H3K4me3 and RNA levels with age are enriched for functional groups commonly implicated in aging biology. Therefore, our findings suggested divergent roles of H3K4me3 in gene expression regulation during aging, with important implications on aging-dependent pathophysiologies.

Histone modifications, the specific chemical modifications on histone proteins, are key for regulating the packing of DNA, and thus have important influence on diverse biological processes. An intensely studied function of histone modifications is their contribution to regulating gene expression. Recent studies in diverse model organisms demonstrated that the global alterations of particular histone modifications, for instance H3K4me3, extend the lifespan of the organism. However, the underlying molecular mechanisms remain largely unclear. In this study, we monitored whether and how the genome-wide pattern of the histone modification H3K4me3 changes during aging in the somatic cells of the model organism C. elegans. We identified interesting and non-conventional patterns of H3K4me3, which span gene-bodies and are acquired during adulthood, that are particularly prone to changes with aging. This is contrasted to the well-studied H3K4me3 patterns that span transcriptional start sites and 5’ promoter regions and are established early during development, which remain stable with age. Consistent with the close association between H3K4me3 marking and active transcription, we observed that the age-dynamic H3K4me3 markings are highly correlated with corresponding RNA expression changes. Importantly, the genes that are associated with both H3K4me3 and RNA expression changes with age are over-represented for functional groups commonly implicated in aging biology. In summary, our findings revealed a lesser known pattern of H3K4me3 modification that can have important biological roles in aging.

Nutrition and Ageing

The ageing trajectory is plastic and can be slowed down by lifestyle factors, including good nutrition, adequate physical activity and avoidance of smoking. In humans, plant-based diets such as the Mediterranean dietary pattern are associated with healthier ageing and lower risk of age-related disease, whereas obesity accelerates ageing and increases the likelihood of most common complex diseases including CVD, T2D, dementia, musculoskeletal diseases and several cancers. As yet, there is only weak evidence in humans about the molecular mechanisms through which dietary factors modulate ageing but evidence from cell systems and animal models suggest that it is probable that better dietary choices influence all 9 hallmarks of ageing. It seems likely that better eating patterns retard ageing in at least two ways including (i) by reducing pervasive damaging processes such as inflammation, oxidative stress/redox changes and metabolic stress and (ii) by enhancing cellular capacities for damage management and repair. From a societal perspective, there is an urgent imperative to discover, and to implement, cost-effective lifestyle (especially dietary) interventions which enable each of us to age well, i.e. to remain physically and socially active and independent and to minimise the period towards the end of life when individuals suffer from frailty and multi-morbidity.

Fat-specific Dicer deficiency accelerates aging and mitigates several effects of dietary restriction in mice

Aging increases the risk of type 2 diabetes, and this can be prevented by dietary restriction (DR). We have previously shown that DR inhibits the downregulation of miRNAs and their processing enzymes - mainly Dicer - that occurs with aging in mouse white adipose tissue (WAT). Here we used fat-specific Dicer knockout mice (AdicerKO) to understand the contributions of adipose tissue Dicer to the metabolic effects of aging and DR. Metabolomic data uncovered a clear distinction between the serum metabolite profiles of Lox control and AdicerKO mice, with a notable elevation of branched-chain amino acids (BCAA) in AdicerKO. These profiles were associated with reduced oxidative metabolism and increased lactate in WAT of AdicerKO mice and were accompanied by structural and functional changes in mitochondria, particularly under DR. AdicerKO mice displayed increased mTORC1 activation in WAT and skeletal muscle, where Dicer expression is not affected. This was accompanied by accelerated age-associated insulin resistance and premature mortality. Moreover, DR-induced insulin sensitivity was abrogated in AdicerKO mice. This was reverted by rapamycin injection, demonstrating that insulin resistance in AdicerKO mice is caused by mTORC1 hyperactivation. Our study evidences a DR-modulated role for WAT Dicer in controlling metabolism and insulin resistance.

Dysregulation of both miR-140-3p and miR-140-5p in synovial fluid correlate with osteoarthritis severity

Objectives

This study looked to analyse the expression levels of microRNA-140-3p and microRNA-140-5p in synovial fluid, and their correlations to the severity of disease regarding knee osteoarthritis (OA).

Methods

Knee joint synovial fluid samples were collected from 45 patients with OA of the knee (15 mild, 15 moderate and 15 severe), ten healthy volunteers, ten patients with gouty arthritis, and ten with rheumatoid arthritis. The Kellgren–Lawrence grading (KLG) was used to assess the radiological severity of knee OA, and the patients were stratified into mild (KLG < 2), moderate (KLG = 2), and severe (KLG > 2). The expression of miR-140-3p and miR-140-5p of individual samples was measured by SYBR Green quantitative polymerase chain reaction (PCR) analysis. The expression of miR-140-3p and miR-140-5p was normalised to U6 internal control using the 2^-△△CT method. All data were processed using SPSS software.

Results

Expression of both miR-140-3p and miR-140-5p was downregulated in OA synovial fluid, showing a statistical difference between the OA and non-OA group, and increased OA severity was associated with a decreased expression of miR-140-3p or miR-140-5p. The Spearman rank correlation analysis suggested that the expression of miR-140-3p or miR-140-5p was negatively correlated with OA severity. In addition, the expression of miR-140-5p was 7.4 times higher than that of miR-140-3p across all groups.

Conclusion

The dysregulation of miR-140-3p and miR-140-5p in synovial fluid and their correlations with the disease severity of OA may provide an important experimental basis for OA classification, and the miR-140-3p/miR-140-5p are of great potential as biomarkers in the diagnosis and clinical management of patients with OA.

Cite this article: C-M. Yin, W-C-W. Suen, S. Lin, X-M. Wu, G. Li, X-H. Pan. Dysregulation of both miR-140-3p and miR-140-5p in synovial fluid correlate with osteoarthritis severity. Bone Joint Res 2017;6:612–618. DOI: 10.1302/2046-3758.611.BJR-2017-0090.R1.

Lung Diseases of the Elderly: Cellular Mechanisms

Natural lung aging is characterized by molecular and cellular changes in multiple lung cell populations. These changes include shorter telomeres, increased expression of cellular senescence markers, increased DNA damage, oxidative stress, apoptosis, and stem cell exhaustion. Aging, combined with the loss of protective repair processes, correlates with the development and incidence of chronic respiratory diseases, including idiopathic pulmonary fibrosis and chronic obstructive pulmonary disease. Ultimately, it is the interplay of age-related changes in biology and the subsequent responses to environmental exposures that largely define the physiology and clinical course of the aging lung.

THE ENDOCRINOLOGY OF AGING: A KEY TO LONGEVITY "GREAT EXPECTATIONS"

ABBREVIATIONS

AMP = adenosine monophosphate CETP = cholesteryl ester transfer protein FOXO = Forkhead box O GH = growth hormone HDL = high-density lipoprotein IGF-1 = insulin-like growth factor 1 LDL = low-density lipoprotein miRNA = microRNA mTOR = mammalian target of rapamycin SIRT = sirtuin T4 = thyroxine TSH = thyroid-stimulating hormone "The Moving Finger writes; and, having writ, Moves on: nor all thy Piety nor Wit Shall lure it back to cancel half a Line, Nor all thy Tears wash out a Word of it." Omar Khayyam ( 1 ).

MicroRNA-434-3p regulates age-related apoptosis through eIF5A1 in the skeletal muscle

Increased activation of catabolic pathways, including apoptosis causes sarcopenia. However, the precise molecular mechanism that initiates apoptosis during aging is not well understood. Here, we report that aging alters miRNA expression profile in mouse skeletal muscle as evidenced by miRNA microarray and real-time PCR. We identified miR-434-3p as a highly downregulated miRNA in the skeletal muscle of aging mice. Myocytes transfected with miR-434-3p mimic prevents apoptosis induced by various apoptotic stimuli, and co-transfection of miR-434-3p antagomir abolishes the inhibitory role of miR-434-3p. We found that miR-434-3p inhibits apoptosis by targeting the eukaryotic translation initiation factor 5A1 (eIF5A1). Overexpression of miR-434-3p in myocytes reduces the loss of mitochondrial transmembrane potential, and activation of caspases-3, -8 and -9 by suppressing eIF5A1 in response to various apoptotic stimuli whereas inhibition of miR-434-3p reversed this scenario. Skeletal muscles from aging mice exhibit low levels of miR-434-3p and high levels of eIF5A1, suggesting a possible role for miR-434-3p in the initiation of apoptosis in aging muscle. Overall, our data identified for the first time that miR-434-3p is an anti-apoptotic miRNA that may be therapeutically useful for treating muscle atrophy in various pathophysiological conditions, including sarcopenia.

Dihydrotestosterone treatment rescues the decline in protein synthesis as a result of sarcopenia in isolated mouse skeletal muscle fibres

BACKGROUND

Sarcopenia, the progressive decline in skeletal muscle mass and function with age, is a debilitating condition. It leads to inactivity, falls, and loss of independence. Despite this, its cause(s) and the underlying mechanism(s) are still poorly understood.

METHODS

In this study, small skeletal muscle fibre bundles isolated from the extensor digitorum longus (a fast-twitch muscle) and the soleus (a slow-twitch muscle) of adult mice of different ages (range 100-900 days old) were used to investigate the effects of ageing and dihydrotestosterone (DHT) treatment on protein synthesis as well as the expression and function of two amino acid transporters; the sodium-coupled neutral amino acid transporter (SNAT) 2, and the sodium-independent L-type amino-acid transporter (LAT) 2.

RESULTS

At all ages investigated, protein synthesis was always higher in the slow-twitch than in the fast-twitch muscle fibres and decreased with age in both fibre types. However, the decline was greater in the fast-twitch than in the slow-twitch fibres and was accompanied by a reduction in the expression of SNAT2 and LAT2 at the protein level. Again, the decrease in the expression of the amino acid transporters was greater in the fast-twitch than in the slow-twitch fibres. In contrast, ageing had no effect on SNAT2 and LAT2 expressions at the mRNA level. Treating the muscle fibre bundles with physiological concentrations (~2 nM) of DHT for 1 h completely reversed the effects of ageing on protein synthesis and the expression of SNAT2 and LAT2 protein in both fibre types.

CONCLUSION

From the observations that ageing is accompanied by a reduction in protein synthesis and transporter expression and that these effects are reversed by DHT treatment, we conclude that sarcopenia arises from an age-dependent reduction in protein synthesis caused, in part, by the lack of or by the low bioavailability of the male sex steroid, DHT.

Prostate Cancer: Is It a Battle Lost to Age?

Age is often considered an important non-modifiable risk factor for a number of diseases, including prostate cancer. Some prominent risk factors of prostate cancer include familial history, ethnicity and age. In this review, various genetic and physiological characteristics affected due to advancing age will be analysed and correlated with their direct effect on prostate cancer.

Replenishment of microRNA-188-5p restores the synaptic and cognitive deficits in 5XFAD Mouse Model of Alzheimer's Disease

MicroRNAs have emerged as key factors in development, neurogenesis and synaptic functions in the central nervous system. In the present study, we investigated a pathophysiological significance of microRNA-188-5p (miR-188-5p) in Alzheimer's disease (AD). We found that oligomeric Aβ_1-42 treatment diminished miR-188-5p expression in primary hippocampal neuron cultures and that miR-188-5p rescued the Aβ_1-42-mediated synapse elimination and synaptic dysfunctions. Moreover, the impairments in cognitive function and synaptic transmission observed in 7-month-old five familial AD (5XFAD) transgenic mice, were ameliorated via viral-mediated expression of miR-188-5p. miR-188-5p expression was down-regulated in the brain tissues from AD patients and 5XFAD mice. The addition of miR-188-5p rescued the reduction in dendritic spine density in the primary hippocampal neurons treated with oligomeric Aβ_1-42 and cultured from 5XFAD mice. The reduction in the frequency of mEPSCs was also restored by addition of miR-188-5p. The impairments in basal fEPSPs and cognition observed in 7-month-old 5XFAD mice were ameliorated via the viral-mediated expression of miR-188-5p in the hippocampus. Furthermore, we found that miR-188 expression is CREB-dependent. Taken together, our results suggest that dysregulation of miR-188-5p expression contributes to the pathogenesis of AD by inducing synaptic dysfunction and cognitive deficits associated with Aβ-mediated pathophysiology in the disease.

Noncoding Transcriptional Landscape in Human Aging

Aging is a universal phenomenon in metazoans, characterized by a general decline of the organism physiology associated with an increased risk of mortality and morbidity. Aging of an organism correlates with a decline in function of its cells, as shown for muscle, immune, and neuronal cells. As the DNA content of most cells within an organism remains largely identical throughout the life span, age-associated transcriptional changes must be achieved by epigenetic mechanisms. However, how aging may impact on the epigenetic state of cells is only beginning to be understood. In light of a growing number of studies demonstrating that noncoding RNAs can provide molecular signals that regulate expression of protein-coding genes and define epigenetic states of cells, we hypothesize that noncoding RNAs could play a direct role in inducing age-associated profiles of gene expression. In this context, the role of long noncoding RNAs (lncRNAs) as regulators of gene expression might be important for the overall transcriptional landscape observed in aged human cells. The possible functions of lncRNAs and other noncoding RNAs, and their roles in the regulation of aging-related cellular pathways will be analyzed.

Age-driven developmental drift in the pathogenesis of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and usually lethal disease of unknown aetiology. A growing body of evidence supports that IPF represents an epithelial-driven process characterised by aberrant epithelial cell behaviour, fibroblast/myofibroblast activation and excessive accumulation of extracellular matrix with the subsequent destruction of the lung architecture. The mechanisms involved in the abnormal hyper-activation of the epithelium are unclear, but we propose that recapitulation of pathways and processes critical to embryological development associated with a tissue specific age-related stochastic epigenetic drift may be implicated. These pathways may also contribute to the distinctive behaviour of IPF fibroblasts. Genomic and epigenomic studies have revealed that wingless/Int, sonic hedgehog and other developmental signalling pathways are reactivated and deregulated in IPF. Moreover, some of these pathways cross-talk with transforming growth factor-β activating a profibrotic feedback loop. The expression pattern of microRNAs is also dysregulated in IPF and exhibits a similar expression profile to embryonic lungs. In addition, senescence, a process usually associated with ageing, which occurs early in alveolar epithelial cells of IPF lungs, likely represents a conserved programmed developmental mechanism. Here, we review the major developmental pathways that get twisted in IPF, and discuss the connection with ageing and potential therapeutic approaches.

Epigenetics and aging

Over the past decade, a growing number of studies have revealed that progressive changes to epigenetic information accompany aging in both dividing and nondividing cells. Functional studies in model organisms and humans indicate that epigenetic changes have a huge influence on the aging process. These epigenetic changes occur at various levels, including reduced bulk levels of the core histones, altered patterns of histone posttranslational modifications and DNA methylation, replacement of canonical histones with histone variants, and altered noncoding RNA expression, during both organismal aging and replicative senescence. The end result of epigenetic changes during aging is altered local accessibility to the genetic material, leading to aberrant gene expression, reactivation of transposable elements, and genomic instability. Strikingly, certain types of epigenetic information can function in a transgenerational manner to influence the life span of the offspring. Several important conclusions emerge from these studies: rather than being genetically predetermined, our life span is largely epigenetically determined; diet and other environmental influences can influence our life span by changing the epigenetic information; and inhibitors of epigenetic enzymes can influence life span of model organisms. These new findings provide better understanding of the mechanisms involved in aging. Given the reversible nature of epigenetic information, these studies highlight exciting avenues for therapeutic intervention in aging and age-associated diseases, including cancer.

miRNA-216 and miRNA-499 target cyb561d2 in zebrafish in response to fipronil exposure

MicroRNA (miRNA) can regulate the expression of its target gene by mediating mRNA cleavage or by translational repression at a post-transcriptional level. Usually, one miRNA may regulate many genes as its targets, while one gene may also be targeted by many miRNAs. We previously demonstrated that cyb561d2, whose protein product is involved in cell defense, and chemical stress, is targeted by miR-155 in adult zebrafish (Danio rerio) when exposed to fipronil (5-amino-1-[2,6-dichloro-4-(trifluoromethyl) phenyl]-4-[(trifluoromethyl) sulphinyl]-1H-pyrazole-3-carbonitrile). Microcosm Targets prediction showed that the cyb561d2 gene is also highly possibly targeted by miR-194a, miR-216b, miR-429, and miR-499. These interactions need to be further validated experimentally. In this study, we evaluated the effects of fipronil on miR-194a, miR-216b, miR-429, miR-499 and cyb561d2 in zebrafish and investigated whether these four miRNAs could regulate the expression of cyb561d2 in both mRNA and protein levels. The expression of cyb561d2 was upregulated in both mRNA and protein level in a dose-dependent manner upon stimulation of fipronil, and miR-216b and miR-499 were downregulated concurrently, whereas there was no significant changes were observed in the expression level of miR-194a and miR-429. The dual luciferase report assay demonstrated that miR-216b and miR-499 interacted with cyb561d2 3'-untranslated regions (3'-UTR), miR-194a and miR-429 did not stimulate degradation of cyb561d2 mRNA. The expression of cyb561d2 was reduced in both mRNA and protein level when ZF4 cells were transfected with miR-499 mimic, whereas expression level of both mRNA and protein was increased when endogenous miR-499 was inhibited by transfection with miR-499 inhibitor. Likewise, the mRNA and protein level of cyb561d2 was affected by treatment with the mimics and the inhibitor of miR-216b. In contrast, when ZF4 cells were transfected with a mimic of miR-194a or miR-429, the expression of cyb561d2 mRNA was not significantly changed. As a result, cyb561d2 is targeted by miR-155, miR-216b and miR-499 upon fipronil exposure, and miR-194a and miR-429 can not target cyb561d2. The expression pattern of these 3 miRNAs presents novel fipronil responses that could be used as a toxicological biomarker.

Differential Expression of microRNA in Cerebrospinal Fluid as a Potential Novel Biomarker for Alzheimer's Disease

BACKGROUND AND OBJECTIVE

The need to find a better reflection of Alzheimer's disease (AD) pathophysiology led us to investigate differential expression of microRNA (miRNA) in cerebrospinal fluid (CSF) of AD patients compared to matched controls, using a genome-wide data-driven approach.

METHODS

From the Amsterdam Dementia Cohort, we selected 19 AD patients with CSF indicative of AD pathophysiology and 19 age and gender-matched controls without CSF evidence of AD (67 ± 6 years old, 20 [53%] female). We measured 754 miRNA in CSF using qRT-PCR (Taqman Array MicroRNA cards A and B, v3.0) according to the Megaplex Taqman protocol. Hierarchical cluster analysis was performed and groups were compared using Linear Models for Microarray Data, a modified t-test. We performed validation analysis using qRT-PCR single assays.

RESULTS

144 ± 66 miRNA could be detected using Megaplex array analysis (19% ). Mean Ct (average 32.4 ± 0.5) was correlated to age (r = 0.52, p = 0.001). Five miRNA were differentially expressed in CSF of AD patients. None of these could be replicated. After stratification by age, seven miRNA showed differential expression in late-onset AD, of which lower abundance of let-7a was replicated (log10RQ -1.46, p <  0.05). In early-onset AD, twelve miRNA were differentially expressed of which lower abundance of miRNA-532-3p remained borderline significant (log10RQ -1.27, p = 0.05).

CONCLUSION

Although we could not consistently separate AD patients and controls in the whole group, we have found indications miRNA in CSF are able to reflect aging and perhaps also heterogeneity in AD. Further investigation requires optimizing RNA input, while maintaining strict age matching.