MiR-34 modulates Caenorhabditis elegans lifespan via repressing the autophagy gene atg9

Research Progress of Aging-related MicroRNAs

Senescence refers to the irreversible state in which cells enter cell cycle arrest due to internal or external stimuli. The accumulation of senescent cells can lead to many age-related diseases, such as neurodegenerative diseases, cardiovascular diseases, and cancers. MicroRNAs are short non-coding RNAs that bind to target mRNA to regulate gene expression after transcription and play an important regulatory role in the aging process. From nematodes to humans, a variety of miRNAs have been confirmed to alter and affect the aging process. Studying the regulatory mechanisms of miRNAs in aging can further deepen our understanding of cell and body aging and provide a new perspective for the diagnosis and treatment of aging-related diseases. In this review, we illustrate the current research status of miRNAs in aging and discuss the possible prospects for clinical applications of targeting miRNAs in senile diseases.

Regulation of miR-61 and col-19 via TGF-β and Notch signalling in Caenorhabditis elegans against Klebsiella aerogenes infection

Klebsiella aerogenes, previously known as Enterobacter aerogenes, is a gram-negative bacterium typically present in the gastrointestinal tract. While numerous studies reported the pathogenicity and drug resistance of this bacterium there remains a lack of comprehensive research on K. aerogenes induced alterations in the host cellular mechanisms. In this study, we identify a previously uncharacterized C. elegans miR-61 that defines an evolutionarily conserved miRNA important for development and innate immunity regulation through Notch and TGF-β signaling pathway. We employed C. elegans wild-type (N2) as well as mutant strains, such as TGF-β (sma-6) and notch-signaling pathway mutants (adm-4 and mir-61). Our results have demonstrated that the K. aerogenes infected mutants exhibited significantly reduced survival rate, reduced pharyngeal pumping, altered swimming and chemotactic behavior. Moreover, K. aerogenes affects the healthspan by increasing ROS level in the mutants. The gene expression analysis revealed that K. aerogenes upregulated egl-30, tph-1 and sod-1 in adm-4, mir-61 mutants not in sma-6. The in-silico analysis indicated an interaction between mir-61 and col-19, which was confirmed by the upregulation of miR-61 expression and the downregulation of col-19 in sma-6, adm-4, and wild-type strains. These findings suggest that C. elegans activates mir-61 and col-19 regulation through the Notch and TGF-β signaling pathway against K. aerogenes infection.

Advances in epigenetic modifications of autophagic process in pulmonary hypertension

Pulmonary hypertension is characterized by pulmonary arterial remodeling that results in increased pulmonary vascular resistance, right ventricular failure, and premature death. It is a threat to public health globally. Autophagy, as a highly conserved self-digestion process, plays crucial roles with autophagy-related (ATG) proteins in various diseases. The components of autophagy in the cytoplasm have been studied for decades and multiple studies have provided evidence of the importance of autophagic dysfunction in pulmonary hypertension. The status of autophagy plays a dynamic suppressive or promotive role in different contexts and stages of pulmonary hypertension development. Although the components of autophagy have been well studied, the molecular basis for the epigenetic regulation of autophagy is less understood and has drawn increasing attention in recent years. Epigenetic mechanisms include histone modifications, chromatin modifications, DNA methylation, RNA alternative splicing, and non-coding RNAs, which control gene activity and the development of an organism. In this review, we summarize the current research progress on epigenetic modifications in the autophagic process, which have the potential to be crucial and powerful therapeutic targets against the autophagic process in pulmonary hypertension development.

MicroRNAs in Age-Related Proteostasis and Stress Responses

Aging is associated with the accumulation of damaged and misfolded proteins through a decline in the protein homeostasis (proteostasis) machinery, leading to various age-associated protein misfolding diseases such as Huntington's or Parkinson's. The efficiency of cellular stress response pathways also weakens with age, further contributing to the failure to maintain proteostasis. MicroRNAs (miRNAs or miRs) are a class of small, non-coding RNAs (ncRNAs) that bind target messenger RNAs at their 3'UTR, resulting in the post-transcriptional repression of gene expression. From the discovery of aging roles for lin-4 in C. elegans, the role of numerous miRNAs in controlling the aging process has been uncovered in different organisms. Recent studies have also shown that miRNAs regulate different components of proteostasis machinery as well as cellular response pathways to proteotoxic stress, some of which are very important during aging or in age-related pathologies. Here, we present a review of these findings, highlighting the role of individual miRNAs in age-associated protein folding and degradation across different organisms. We also broadly summarize the relationships between miRNAs and organelle-specific stress response pathways during aging and in various age-associated diseases.

miR-34a/DRP-1-mediated mitophagy participated in cisplatin-induced ototoxicity via increasing oxidative stress

PURPOSE

Cisplatin is a widely used and effective chemotherapeutic agent for most solid malignant tumors. However, cisplatin-induced ototoxicity is a common adverse effect that limits the therapeutic efficacy of tumors in the clinic. To date, the specific mechanism of ototoxicity has not been fully elucidated, and the management of cisplatin-induced ototoxicity is also an urgent challenge. Recently, some authors believed that miR34a and mitophagy played a role in age-related and drug-induced hearing loss. Our study aimed to explore the involvement of miR-34a/DRP-1-mediated mitophagy in cisplatin-induced ototoxicity.

METHODS

In this study, C57BL/6 mice and HEI-OC1 cells were treated with cisplatin. MiR-34a and DRP-1 levels were analyzed by qRT‒PCR and western blotting, and mitochondrial function was assessed via oxidative stress, JC-1 and ATP content. Subsequently, we detected DRP-1 levels and observed mitochondrial function by modulating miR-34a expression in HEI-OC1 cells to determine the effect of miR-34a on DRP-1-mediated mitophagy.

RESULTS

MiR-34a expression increased and DRP-1 levels decreased in C57BL/6 mice and HEI-OC1 cells treated with cisplatin, and mitochondrial dysfunction was involved in this process. Furthermore, the miR-34a mimic decreased DRP-1 expression, enhanced cisplatin-induced ototoxicity and aggravated mitochondrial dysfunction. We further verified that the miR-34a inhibitor increased DRP-1 expression, partially protected against cisplatin-induced ototoxicity and improved mitochondrial function.

CONCLUSION

MiR-34a/DRP-1-mediated mitophagy was related to cisplatin-induced ototoxicity and might be a novel target for investigating the treatment and protection of cisplatin-induced ototoxicity.

Nanomedicine for autophagy modulation in cancer therapy: a clinical perspective

In recent years, progress in nanotechnology provided new tools to treat cancer more effectively. Advances in biomaterials tailored for drug delivery have the potential to overcome the limited selectivity and side effects frequently associated with traditional therapeutic agents. While autophagy is pivotal in determining cell fate and adaptation to different challenges, and despite the fact that it is frequently dysregulated in cancer, antitumor therapeutic strategies leveraging on or targeting this process are scarce. This is due to many reasons, including the very contextual effects of autophagy in cancer, low bioavailability and non-targeted delivery of existing autophagy modulatory compounds. Conjugating the versatile characteristics of nanoparticles with autophagy modulators may render these drugs safer and more effective for cancer treatment. Here, we review current standing questions on the biology of autophagy in tumor progression, and precursory studies and the state-of-the-art in harnessing nanomaterials science to enhance the specificity and therapeutic potential of autophagy modulators.

Cellular autophagy, the compelling roles in hearing function and dysfunction

Sensorineural hearing loss (SNHL) is currently a major health issue. As one of the most common neurodegenerative diseases, SNHL is associated with the degradation of hair cells (HCs), spiral ganglion neurons (SGNs), the stria vascularis, supporting cells and central auditory system cells. Autophagy is a highly integrated cellular system that eliminates impaired components and replenishes energy to benefit cellular homeostasis. Etiological links between autophagy alterations and neurodegenerative diseases, such as SNHL, have been established. The hearing pathway is complex and depends on the comprehensive functions of many types of tissues and cells in auditory system. In this review, we discuss the roles of autophagy in promoting and inhibiting hearing, paying particular attention to specific cells in the auditory system, as discerned through research. Hence, our review provides enlightening ideas for the role of autophagy in hearing development and impairment.

MicroRNA-34a: A Novel Therapeutic Target in Fibrosis

Fibrosis can occur in many organs, and severe cases leading to organ failure and death. No specific treatment for fibrosis so far. In recent years, microRNA-34a (miR-34a) has been found to play a role in fibrotic diseases. MiR-34a is involved in the apoptosis, autophagy and cellular senescence, also regulates TGF-β1/Smad signal pathway, and negatively regulates the expression of multiple target genes to affect the deposition of extracellular matrix and regulate the process of fibrosis. Some studies have explored the efficacy of miR-34a-targeted therapies for fibrotic diseases. Therefore, miR-34a has specific potential for the treatment of fibrosis. This article reviews the important roles of miR-34a in fibrosis and provides the possibility for miR-34a as a novel therapeutic target in fibrosis.

The Role of MicroRNAs in Proteostasis Decline and Protein Aggregation during Brain and Skeletal Muscle Aging

Aging can be defined as the progressive deterioration of cellular, tissue, and organismal function over time. Alterations in protein homeostasis, also known as proteostasis, are a hallmark of aging that lead to proteome imbalances and protein aggregation, phenomena that also occur in age-related diseases. Among the various proteostasis regulators, microRNAs (miRNAs) have been reported to play important roles in the post-transcriptional control of genes involved in maintaining proteostasis during the lifespan in several organismal tissues. In this review, we consolidate recently published reports that demonstrate how miRNAs regulate fundamental proteostasis-related processes relevant to tissue aging, with emphasis on the two most studied tissues, brain tissue and skeletal muscle. We also explore an emerging perspective on the role of miRNA regulatory networks in age-related protein aggregation, a known hallmark of aging and age-related diseases, to elucidate potential miRNA candidates for anti-aging diagnostic and therapeutic targets.

Transcriptional and Post-Transcriptional Regulation of Autophagy

Autophagy is a widely conserved process in eukaryotes that is involved in a series of physiological and pathological events, including development, immunity, neurodegenerative disease, and tumorigenesis. It is regulated by nutrient deprivation, energy stress, and other unfavorable conditions through multiple pathways. In general, autophagy is synergistically governed at the RNA and protein levels. The upstream transcription factors trigger or inhibit the expression of autophagy- or lysosome-related genes to facilitate or reduce autophagy. Moreover, a significant number of non-coding RNAs (microRNA, circRNA, and lncRNA) are reported to participate in autophagy regulation. Finally, post-transcriptional modifications, such as RNA methylation, play a key role in controlling autophagy occurrence. In this review, we summarize the progress on autophagy research regarding transcriptional regulation, which will provide the foundations and directions for future studies on this self-eating process.

Parkinson's disease and microRNAs - Lessons from model organisms and human studies

Parkinson's disease (PD) is a progressive, age-associated neurodegenerative disorder that affects an estimated 10 million people worldwide. PD is characterized by proteinaceous, cytoplasmic inclusions containing α-synuclein, called Lewy Bodies, which form in dopaminergic neurons in an age-dependent manner, and are associated with the emergence of characteristic PD symptoms such as resting tremor, rigidity, slow movements and postural instability. Although considerable progress has been made in recent years in identifying genetic and environmental factors that are associated with PD, early diagnosis and therapeutic options remain severely lacking. Recently, microRNAs (miRNAs) have emerged as novel therapeutic targets in various diseases, such as cancer and neurodegenerative diseases. MiRNAs have been shown to play roles in various aging and neurodegenerative disease models across phyla. More recently, studies have identified specific roles for miRNAs and their targets in the pathogenesis and progression of PD in several model organisms. Here, we discuss the evolving field of miRNAs, their association with PD, and the outlook for the future.

Key miRNAs in Modulating Aging and Longevity: A Focus on Signaling Pathways and Cellular Targets

Aging is a multifactorial procedure accompanied by gradual deterioration of most biological procedures of cells. MicroRNAs (miRNAs) are a class of short non-coding RNAs that post-transcriptionally regulate the expression of mRNAs through sequence-specific binding, and contributing to many crucial aspects of cell biology. Several miRNAs are expressed differently in various organisms through aging. The function of miRNAs in modulating aging procedures has been disclosed recently with the detection of miRNAs that modulate longevity in the invertebrate model organisms, through the IIS pathway. In these model organisms, several miRNAs have been detected to both negatively and positively regulate lifespan via commonly aging pathways. miRNAs modulate age-related procedures and disorders in different mammalian tissues by measuring their tissue-specific expression in older and younger counterparts, including heart, skin, bone, brain, and muscle tissues. Moreover, several miRNAs have been contributed to modulating senescence in different human cells, and the roles of these miRNAs in modulating cellular senescence have allowed illustrating some mechanisms of aging. The review discusses the available data on miRNAs through the aging process and we highlight the roles of miRNAs as aging biomarkers and regulators of longevity in cellular senescence, tissue aging, and organism lifespan.

Rare genetic coding variants associated with human longevity and protection against age-related diseases

Extreme longevity in humans has a strong genetic component, but whether this involves genetic variation in the same longevity pathways as found in model organisms is unclear. Using whole-exome sequences of a large cohort of Ashkenazi Jewish centenarians to examine enrichment for rare coding variants, we found most longevity-associated rare coding variants converge upon conserved insulin/insulin-like growth factor 1 signaling and AMP-activating protein kinase signaling pathways. Centenarians have a number of pathogenic rare coding variants similar to control individuals, suggesting that rare variants detected in the conserved longevity pathways are protective against age-related pathology. Indeed, we detected a pro-longevity effect of rare coding variants in the Wnt signaling pathway on individuals harboring the known common risk allele APOE4. The genetic component of extreme human longevity constitutes, at least in part, rare coding variants in pathways that protect against aging, including those that control longevity in model organisms.

Autophagy in healthy aging and disease

Autophagy is a fundamental cellular process that eliminates molecules and subcellular elements, including nucleic acids, proteins, lipids and organelles, via lysosome-mediated degradation to promote homeostasis, differentiation, development and survival. While autophagy is intimately linked to health, the intricate relationship among autophagy, aging and disease remains unclear. This Review examines several emerging features of autophagy and postulates how they may be linked to aging as well as to the development and progression of disease. In addition, we discuss current preclinical evidence arguing for the use of autophagy modulators as suppressors of age-related pathologies such as neurodegenerative diseases. Finally, we highlight key questions and propose novel research avenues that will likely reveal new links between autophagy and the hallmarks of aging. Understanding the precise interplay between autophagy and the risk of age-related pathologies across organisms will eventually facilitate the development of clinical applications that promote long-term health.

Autophagy: A Novel Horizon for Hair Cell Protection

As a general sensory disorder, hearing loss was a major concern worldwide. Autophagy is a common cellular reaction to stress that degrades cytoplasmic waste through the lysosome pathway. Autophagy not only plays major roles in maintaining intracellular homeostasis but is also involved in the development and pathogenesis of many diseases. In the auditory system, several studies revealed the link between autophagy and hearing protection. In this review, we aimed to establish the correlation between autophagy and hair cells (HCs) from the aspects of ototoxic drugs, aging, and acoustic trauma and discussed whether autophagy could serve as a potential measure in the protection of HCs.

Epigenetic Regulation of Autophagy in Cardiovascular Pathobiology

Cardiovascular diseases (CVDs) are the number one cause of debilitation and mortality worldwide, with a need for cost-effective therapeutics. Autophagy is a highly conserved catabolic recycling pathway triggered by various intra- or extracellular stimuli to play an essential role in development and pathologies, including CVDs. Accordingly, there is great interest in identifying mechanisms that govern autophagic regulation. Autophagic regulation is very complex and multifactorial that includes epigenetic pathways, such as histone modifications to regulate autophagy-related gene expression, decapping-associated mRNA degradation, microRNAs, and long non-coding RNAs; pathways are also known to play roles in CVDs. Molecular understanding of epigenetic-based pathways involved in autophagy and CVDs not only will enhance the understanding of CVDs, but may also provide novel therapeutic targets and biomarkers for CVDs.

MiR-34a suppression targets Nampt to ameliorate bone marrow mesenchymal stem cell senescence by regulating NAD+-Sirt1 pathway

BACKGROUND

Expansion-mediated replicative senescence and age-related natural senescence have adverse effects on mesenchymal stem cell (MSC) regenerative capability and functionality, thus severely impairing the extensive applications of MSC-based therapies. Emerging evidences suggest that microRNA-34a (miR-34a) has been implicated in the process of MSC senescence; however, the molecular mechanisms with regard to how miR-34a influencing MSC senescence remain largely undetermined.

METHODS

MiR-34a expression in MSCs was evaluated utilizing RT-qPCR. The functional effects of miR-34a exerting on MSC senescence were investigated via gene manipulation. Relevant gene and protein expression levels were analyzed by RT-qPCR and western blot. Luciferase reporter assays were applied to confirm that Nampt is a direct target of miR-34a. The underlying regulatory mechanism of miR-34a targeting Nampt in MSC senescence was further explored by measuring intracellular NAD⁺ content, NAD⁺/NADH ratio and Sirt1 activity.

RESULTS

In contrast to Nampt expression, miR-34a expression incremented in senescent MSCs. MiR-34a overexpression in young MSCs resulted in senescence-associated characteristics as displayed by senescence-like morphology, prolonged cell proliferation, declined osteogenic differentiation potency, heightened senescence-associated-β-galactosidase activity, and upregulated expression levels of the senescence-associated factors. Conversely, miR-34a suppression in replicative senescent and natural senescent MSCs contributed to diminished senescence-related phenotypic features. We identified Nampt as a direct target gene of miR-34a. In addition, miR-34a repletion resulted in prominent reductions in Nampt expression levels, NAD⁺ content, NAD⁺/NADH ratio, and Sirt1 activity, whereas anti-miR-34a treatment exerted the opposite effects. Furthermore, miR-34a-mediated MSC senescence was evidently rescued following the co-treatment with Nampt overexpression.

CONCLUSION

This study identifies a significant role of miR-34a playing in MSC replicative senescence and natural senescence via targeting Nampt and further mediating by NAD⁺-Sirt1 pathway, carrying great implications for optimal strategies for MSC therapeutic applications.

The interplay of microRNAs and transcription factors in autophagy regulation in nonalcoholic fatty liver disease

The autophagy-lysosomal degradation system has an important role in maintaining liver homeostasis by removing unnecessary intracellular components. Impaired autophagy has been linked to nonalcoholic fatty liver disease (NAFLD), which includes hepatitis, steatosis, fibrosis, and cirrhosis. Thus, gaining an understanding of the mechanisms that regulate autophagy and how autophagy contributes to the development and progression of NAFLD has become the focus of recent studies. Autophagy regulation has been thought to be primarily regulated by cytoplasmic processes; however, recent studies have shown that microRNAs (miRNAs) and transcription factors (TFs) also act as key regulators of autophagy by targeting autophagy-related genes. In this review, we summarize the miRNAs and TFs that regulate the autophagy pathway in NAFLD. We further focus on the transcriptional and posttranscriptional regulation of autophagy and discuss the complex regulatory networks involving these regulators in autophagy. Finally, we highlight the potential of targeting miRNAs and TFs involved in the regulation of autophagy for the treatment of NAFLD.

miR34a: a novel small molecule regulator with a big role in bronchopulmonary dysplasia

Preterm infants with bronchopulmonary dysplasia (BPD), characterized by pulmonary inflammation leading to impaired alveolarization and vascular dysregulation, have an increased risk of abnormal lung function in infancy, childhood, and adulthood. These include a heightened risk of pulmonary hypertension, and respiratory illnesses. MicroRNAs (miRNAs) are known to disrupt normal lung development and function by interrupting alveolarization and vascularization resulting in the development of BPD. Among the various miRs involved in BPD, miR34a has been shown to have a significant role in BPD pathogenesis. Targeting miR34a or its downstream targets may be a promising therapeutic intervention for BPD. In this review, we summarize the data on cellular arrest, proliferation, differentiation, epithelial-mesenchymal transition, mitochondrial dysfunction, and apoptosis impacted by miR34a in the development of BPD pulmonary phenotypes while predicting the future perspective of miR34a in BPD.

MiR-127-3p targeting CISD1 regulates autophagy in hypoxic-ischemic cortex

Neonatal hypoxic-ischemic (HI) injury derived from asphyxia during perinatal period, is a serious complication of neonatal asphyxia and the main cause of neonatal acute death and chronic neurological injury. Aberrant autophagy occurs in many nervous system diseases, but its role and underlying mechanism in HI injury is largely unknown. Here, we successfully constructed a newborn rat model of HI brain injury, and the knockout-miR-127-3p (KO-miR-127-3p) rats were structured by using CRISPR/Cas9. Subsequently, the in vitro functional experiments, in vivo zea-longa scores, as well as bioinformatics analyses and biological experiments were applied. The expression of autophagy-related proteins, including ATG12, P62, Beclin-1, LC3II in HI cortex with miR-127-3p knockout was significantly decreased, and autophagic vacuoles were disappeared. Moreover, miR-127-3p has a specific regulatory effect on CISD1 expression, another crucial molecule in autophagy process. Accordingly, the overexpression of CISD1 effectively inhibited the autophagic cell death and physiological dysfunction in the brain of HI injury, whereas si-CISD1 reversed the neuroprotective effects of KO-miR-127-3p. Our findings explained the underlying mechanism for HI injury, and miR-127-3p targeting CISD1 signal could be supposed as a new treatment strategy to prevent and treat HI injury.

MicroRNAs as Candidate Biomarkers for Alzheimer's Disease

The neurological damage of Alzheimer’s disease (AD) is thought to be irreversible upon onset of dementia-like symptoms, as it takes years to decades for occult pathologic changes to become symptomatic. It is thus necessary to identify individuals at risk for the development of the disease before symptoms manifest in order to provide early intervention. Surrogate markers are critical for early disease detection, stratification of patients in clinical trials, prediction of disease progression, evaluation of response to treatment, and also insight into pathomechanisms. Here, we review the evidence for a number of microRNAs that may serve as biomarkers with possible mechanistic insights into the AD pathophysiologic processes, years before the clinical manifestation of the disease.

Global, cell non-autonomous gene regulation drives individual lifespan among isogenic C. elegans

Across species, lifespan is highly variable among individuals within a population. Even genetically identical Caenorhabditis elegans reared in homogeneous environments are as variable in lifespan as outbred human populations. We hypothesized that persistent inter-individual differences in expression of key regulatory genes drives this lifespan variability. As a test, we examined the relationship between future lifespan and the expression of 22 microRNA promoter::GFP constructs. Surprisingly, expression of nearly half of these reporters, well before death, could effectively predict lifespan. This indicates that prospectively long- vs. short-lived individuals have highly divergent patterns of transgene expression and transcriptional regulation. The gene-regulatory processes reported on by two of the most lifespan-predictive transgenes do not require DAF-16, the FOXO transcription factor that is a principal effector of insulin/insulin-like growth factor (IGF-1) signaling. Last, we demonstrate a hierarchy of redundancy in lifespan-predictive ability among three transgenes expressed in distinct tissues, suggesting that they collectively report on an organism-wide, cell non-autonomous process that acts to set each individual’s lifespan.

Potential role of specific microRNAs in the regulation of thermal stress response in livestock

Thermal stress is known to have harmful effects on livestock productivity and can cause livestock enterprises considerable financial loss. These effects may be aggravated by climate change. Stress responses to nonspecific systemic actions lead to perturbation of molecular pathways in the organism. The molecular response is regulated in a dynamic and synchronized manner that assurances robustness and flexibility for the restoration of functional and structural homeostasis in stressed cells and tissues. MicroRNAs (miRNAs) are micro molecules of small non-coding RNA that control gene expression at the post-transcriptional level. Recently, various studies have discovered precise types of miRNA that regulate cellular machinery and homeostasis under various types of stress, suggesting a significant role of miRNA in thermal stress responses in animals. The miRNAs revealed in this paper could serve as promising candidates and biomarkers for heat stress and could be used as potential pharmacological targets for mitigating the consequences of thermal stress. Stress miRNA pathways may be associated with thermal stress, which offers some potential approaches to combat the negative impacts of thermal stress in livestock. The review provides new data that can assist the elucidation of the miRNA mechanisms that mediate animals' responses to thermal stress.

MicroRNAs Regulating Autophagy in Neurodegeneration

Social and economic impacts of neurodegenerative diseases (NDs) become more prominent in our constantly aging population. Currently, due to the lack of knowledge about the aetiology of most NDs, only symptomatic treatment is available for patients. Hence, researchers and clinicians are in need of solid studies on pathological mechanisms of NDs. Autophagy promotes degradation of pathogenic proteins in NDs, while microRNAs post-transcriptionally regulate multiple signalling networks including autophagy. This chapter will critically discuss current research advancements in the area of microRNAs regulating autophagy in NDs. Moreover, we will introduce basic strategies and techniques used in microRNA research. Delineation of the mechanisms contributing to NDs will result in development of better approaches for their early diagnosis and effective treatment.

MicroRNA-34a: the bad guy in age-related vascular diseases

The age-related vasculature alteration is the prominent risk factor for vascular diseases (VD), namely, atherosclerosis, abdominal aortic aneurysm, vascular calcification (VC) and pulmonary arterial hypertension (PAH). The chronic sterile low-grade inflammation state, alias inflammaging, characterizes elderly people and participates in VD development. MicroRNA34-a (miR-34a) is emerging as an important mediator of inflammaging and VD. miR-34a increases with aging in vessels and induces senescence and the acquisition of the senescence-associated secretory phenotype (SASP) in vascular smooth muscle (VSMCs) and endothelial (ECs) cells. Similarly, other VD risk factors, including dyslipidemia, hyperglycemia and hypertension, modify miR-34a expression to promote vascular senescence and inflammation. miR-34a upregulation causes endothelial dysfunction by affecting ECs nitric oxide bioavailability, adhesion molecules expression and inflammatory cells recruitment. miR-34a-induced senescence facilitates VSMCs osteoblastic switch and VC development in hyperphosphatemia conditions. Conversely, atherogenic and hypoxic stimuli downregulate miR-34a levels and promote VSMCs proliferation and migration during atherosclerosis and PAH. MiR34a genetic ablation or miR-34a inhibition by anti-miR-34a molecules in different experimental models of VD reduce vascular inflammation, senescence and apoptosis through sirtuin 1 Notch1, and B-cell lymphoma 2 modulation. Notably, pleiotropic drugs, like statins, liraglutide and metformin, affect miR-34a expression. Finally, human studies report that miR-34a levels associate to atherosclerosis and diabetes and correlate with inflammatory factors during aging. Herein, we comprehensively review the current knowledge about miR-34a-dependent molecular and cellular mechanisms activated by VD risk factors and highlight the diagnostic and therapeutic potential of modulating its expression in order to reduce inflammaging and VD burn and extend healthy lifespan.

Nutrition and microRNAs: Novel Insights to Fight Sarcopenia

Sarcopenia is a progressive age-related loss of skeletal muscle mass and strength, which may result in increased physical frailty and a higher risk of adverse events. Low-grade systemic inflammation, loss of muscle protein homeostasis, mitochondrial dysfunction, and reduced number and function of satellite cells seem to be the key points for the induction of muscle wasting, contributing to the pathophysiological mechanisms of sarcopenia. While a range of genetic, hormonal, and environmental factors has been reported to contribute to the onset of sarcopenia, dietary interventions targeting protein or antioxidant intake may have a positive effect in increasing muscle mass and strength, regulating protein homeostasis, oxidative reaction, and cell autophagy, thus providing a cellular lifespan extension. MicroRNAs (miRNAs) are endogenous small non-coding RNAs, which control gene expression in different tissues. In skeletal muscle, a range of miRNAs, named myomiRNAs, are involved in many physiological processes, such as growth, development, and maintenance of muscle mass and function. This review aims to present and to discuss some of the most relevant molecular mechanisms related to the pathophysiological effect of sarcopenia. Besides, we explored the role of nutrition as a possible way to counteract the loss of muscle mass and function associated with ageing, with special attention paid to nutrient-dependent miRNAs regulation. This review will provide important information to better understand sarcopenia and, thus, to facilitate research and therapeutic strategies to counteract the pathophysiological effect of ageing.

Dihydromyricetin Prevents Diabetic Cardiomyopathy via miR-34a Suppression by Activating Autophagy

PURPOSE

The pro-aging miRNA, miR-34a, is hyperactivated in the cardiac myocardial tissues of patients and mice with diabetes, leading to diabetic cardiomyopathy (DCM). Increasing evidence suggests that dihydromyricetin (DHM) can be used to effectively treat cardiomyopathy. In this study, we investigated whether DHM affects the expression of miR-34a in DCM.

METHODS

The expression of miR-34a in high-glucose-induced cardiomyocytes and in the heart tissue of diabetic mice was determined by microRNA isolation and quantitative reverse transcription-polymerase chain reaction. Lipofectamine 3000 was used to transfect cardiomyocytes with miR-34a inhibitor, miR-34a mimics, and miR-control. These agents were intravenously injected into the tail vein of streptozotocin-induced diabetic mice. Autophagy and apoptosis were assessed in high-glucose-induced cardiomyocytes and cardiac tissue in diabetic mice by western blotting, immunofluorescence, Masson staining, hematoxylin and eosin staining (H&E), and electron microscopy.

RESULTS

DHM clearly ameliorated the cardiac dysfunction in the diabetic mice. The expression of miR-34a was up-regulated in high-glucose-induced cardiomyocytes and in the hearts of diabetic mice, thus impairing autophagy. Treatment with DHM decreased the expression of miR-34a and rescued the impairment of autophagy in high-glucose-induced cardiomyocytes and in the heart tissue of diabetic mice, while the miR-34a mimic offset the effect of DHM with respect to the development of DCM by inhibiting autophagy.

CONCLUSIONS

By decreasing the expression of miR-34a, DHM restores impaired autophagy, and thus ameliorates DCM. Therefore, DHM may potentially be used in the treatment of DCM.

Nanomaterials for Autophagy-Related miRNA-34a Delivery in Cancer Treatment

Autophagy is an evolutionary conserved physiological process with a fundamental role during development, differentiation, and survival of eukaryotic cells. On the other hand, autophagy dysregulation is observed in many pathological conditions, including cancer. In particular, tumor growth and progression are accompanied and promoted by increased autophagy that allows cancer cells to escape apoptosis and to proliferate also in harsh microenvironments. It is, therefore, clear that the impairment of the autophagic process may represent a valid strategy to inhibit or reduce cancer growth and progression. Among the plethora of molecular players controlling cancer growth, a group of small endogenous noncoding RNAs called microRNAs (miRNAs) has recently emerged. In fact, miRNAs can act as either oncogenes or oncosuppressors depending on their target genes. Moreover, among miRNAs, miRNA-34a has been connected with both tumor repression and autophagy regulation, and its expression is frequently lost in many cancers. Therefore, enforced expression of miRNA-34a in cancer cells may represent a valid strategy to reduce cancer growth. However, such strategy is limited by the fast biodegradation and short half-life of miRNA-34a and by the lack of an efficient intracellular delivery system. The following review describes the autophagic process and its role in cancer as well as the role of miRNAs in general and miRNA-34a in particular in regulating tumor growth by modulating autophagy. Finally, we describe the use of nanoparticles as a promising strategy to selectively deliver miRNA-34a to tumor cells for therapeutic and diagnostic purposes.

Autophagy modulation in animal models of corneal diseases: a systematic review

Autophagy is an intracellular catabolic process implicated in the recycling and degradation of intracellular components. Few studies have defined its role in corneal pathologies. Animal models are essential for understanding autophagy regulation and identifying new treatments to modulate its effects. A systematic review (SR) was conducted of studies employing animal models for investigations of autophagy in corneal diseases. Studies were identified using a structured search strategy (TS = autophagy AND cornea*) in Web of Science, Scopus, and PubMed from inception to September 2019. In this study, 230 articles were collected, of which 28 were analyzed. Mouse models were used in 82% of the studies, while rat, rabbit, and newt models were used in the other 18%. The most studied corneal layer was the epithelium, followed by the endothelium and stroma. In 13 articles, genetically modified animal models were used to study Fuch endothelial corneal dystrophy (FECD), granular corneal dystrophy type 2 (GCD2), dry eye disease (DED), and corneal infection. In other 13 articles, animal models were experimentally induced to mimic DED, keratitis, inflammation, and surgical scenarios. Furthermore, in 50% of studies, modulators that activated or inhibited autophagy were also investigated. Protective effects of autophagy activators were demonstrated, including rapamycin for DED and keratitis, lithium for FECD, LYN-1604 for DED, cysteamine and miR-34c antagomir for damaged corneal epithelium. Three autophagy suppressors were also found to have therapeutic effects, such as aminoimidazole-4-carboxamide-riboside (AICAR) for corneal allogeneic transplantation, celecoxib and chloroquine for DED.

Autophagy in cancers including brain tumors: role of MicroRNAs

Autophagy has a crucial role in many cancers, including brain tumors. Several types of endogenous molecules (e.g. microRNAs, AKT, PTEN, p53, EGFR, and NF1) can modulate the process of autophagy. Recently miRNAs (small non-coding RNAs) have been found to play a vital role in the regulation of different cellular and molecular processes, such as autophagy. Deregulation of these molecules is associated with the development and progression of different pathological conditions, including brain tumors. It was found that miRNAs are epigenetic regulators, which influence the level of proteins coded by the targeted mRNAs with any modification of the genetic sequences. It has been revealed that various miRNAs (e.g., miR-7-1-3p, miR-340, miR-17, miR-30a, miR-224-3p, and miR-93), as epigenetic regulators, can modulate autophagy pathways within brain tumors. A deeper understanding of the underlying molecular targets of miRNAs, and their function in autophagy pathways could contribute to the development of new treatment methods for patients with brain tumors. In this review, we summarize the various miRNAs, which are involved in regulating autophagy in brain tumors. Moreover, we highlight the role of miRNAs in autophagy-related pathways in different cancers.

Pro-Senescence and Anti-Senescence Mechanisms of Cardiovascular Aging: Cardiac MicroRNA Regulation of Longevity Drug-Induced Autophagy

Chronological aging as well as biological aging accelerated by various pathologies such as diabetes and obesity contribute to cardiovascular aging, and structural and functional tissue damage of the heart and vasculature. Cardiovascular aging in humans is characterized by structural pathologic remodeling including cardiac and vascular fibrosis, hypertrophy, stiffness, micro- and macro-circulatory impairment, left ventricular diastolic dysfunction precipitating heart failure with either reduced or preserved ejection fraction, and cardiovascular cell death. Cellular senescence, an important hallmark of aging, is a critical factor that impairs repair and regeneration of damaged cells in cardiovascular tissues whereas autophagy, an intracellular catabolic process is an essential inherent mechanism that removes senescent cells throughout life time in all tissues. Several recent reviews have highlighted the fact that all longevity treatment paradigms to mitigate progression of aging-related pathologies converge in induction of autophagy, activation of AMP kinase (AMPK) and Sirtuin pathway, and inhibition of mechanistic target of rapamycin (mTOR). These longevity treatments include health style changes such as caloric restriction, and drug treatments using rapamycin, the first FDA-approved longevity drug, as well as other experimental longevity drugs such as metformin, rapamycin, aspirin, and resveratrol. However, in the heart tissue, autophagy induction has to be tightly regulated since evidence show excessive autophagy results in cardiomyopathy and heart failure. Here we discuss emerging evidence for microRNA-mediated tight regulation of autophagy in the heart in response to treatment with rapamycin, and novel approaches to monitor autophagy progression in a temporal manner to diagnose and regulate autophagy induction by longevity treatments.

Epigenetic changes during ageing and their underlying mechanisms

As life expectancy increases worldwide, ageing and age-related diseases arise as a major issue for societies around the globe. Understanding the biological mechanisms underlying the ageing process is thus instrumental for the development of efficient interventions aimed to prevent and treat age-related conditions. Current knowledge in the biogerontology field points to epigenetics as a critical component of the ageing process, not only by serving as a bona-fide marker of biological age but also by controlling and conferring inheritability to cellular and organismal ageing. This is reflected by a myriad of evidences demonstrating the relationship between DNA methylation, histone modifications, chromatin remodeling and small non-coding RNAs and several age-related phenotypes. Given the reversibility of epigenetic alterations, epigenetic reprogramming may also be envisioned as a potential approach to treat age-related disorders. Here we review how different types of epigenetic mechanisms are involved in the ageing process. In addition, we highlight how interventions modulate epigenetics and thus promote health- and lifespan.

Astragaloside-IV protects H9C2(2-1) cardiomyocytes from high glucose-induced injury via miR-34a-mediated autophagy pathway

Diabetic cardiomyopathy (DCM) is an important cardiac disorder in patients with diabetes. High glucose (HG) levels lead to inflammation of cardiomyocytes, oxidative stress, and long-term activation of autophagy, resulting in myocardial fibrosis and remodelling. Astragaloside-IV (AS-IV) has a wide range of pharmacological effects. This study aimed to investigate the effects of AS-IV on injury induced by HG in rat cardiomyocytes (H9C2(2-1)) and the involvement of the miR-34a-mediated autophagy pathway. An AS-IV concentration of 100 μM was selected based on H9C2(2-1) cell viability using the cell counting kit-8 (CCK-8). We found that 33 mM HG induced a morphologic change in cells and caused excessive oxidative stress, whereas AS-IV inhibited lipid peroxidation and increased superoxide dismutase activity. In terms of mRNA expression, HG increased miR-34a and inhibited Bcl2 and Sirt1, whereas AS-IV and miR-34a-inhibitor reversed the above effects. Further, LC3-GFP adenovirus infection and western blotting showed that HG increased autophagy, which was reversed synergistically by AS-IV and miR-34a-inhibitor. Bcl2 and pAKT/AKT protein expressions in the HG group was significantly lower than that in controls, but AS-IV and miR-34a-inhibitor antagonized the process. Thus, AS-IV inhibits HG-induced oxidative stress and autophagy and protects cardiomyocytes from injury via the miR-34a/Bcl2/(LC3II/LC3I) and pAKT/Bcl2/(LC3II/LC3I) pathways.

MicroRNAs as modulators of longevity and the aging process

MicroRNAs (miRNAs) are short, non-coding RNAs that post-transcriptionally repress translation or induce mRNA degradation of target transcripts through sequence-specific binding. miRNAs target hundreds of transcripts to regulate diverse biological pathways and processes, including aging. Many microRNAs are differentially expressed during aging, generating interest in their use as aging biomarkers and roles as regulators of the aging process. In the invertebrates Caenorhabditis elegans and Drosophila, a number of miRNAs have been found to both positive and negatively modulate longevity through canonical aging pathways. Recent studies have also shown that miRNAs regulate age-associated processes and pathologies in a diverse array of mammalian tissues, including brain, heart, bone, and muscle. The review will present an overview of these studies, highlighting the role of individual miRNAs as biomarkers of aging and regulators of longevity and tissue-specific aging processes.

MicroRNA-34a mediates ethanol-induced impairment of neural differentiation of neural crest cells by targeting autophagy-related gene 9a

Neural crest cells (NCCs) are multipotent progenitor cells that are sensitive to ethanol and are implicated in Fetal Alcohol Spectrum Disorders (FASD). The objective of this study is to test whether ethanol exposure can inhibit the neural differentiation of NCCs by inhibiting autophagy and whether miR-34a is involved in ethanol-induced inhibition of autophagy in NCCs. We found that ethanol exposure resulted in the inhibition of neural differentiation of NCCs. Exposure to ethanol also significantly decreased autophagy in NCCs, as indicated by a decreased LC3II/I ratio and an elevated expression of p62 protein. Knockdown of p62 restored the expression of the neurogenesis genes, NF and Mash1, in ethanol-exposed NCCs, suggesting that ethanol exposure can inhibit the neural differentiation of NCCs by inhibiting autophagy. We also found that ethanol exposure resulted in a significant increase in miR-34a expression in NCCs. Inhibition of miR-34a restored the expression of Atg9a, a direct target of miR-34a and significantly decreased ethanol-induced inhibition of autophagy in NCCs. Down-regulation of miR-34a also prevented ethanol-induced inhibition of neural differentiation of NCCs. These results demonstrate that ethanol-induced inhibition of neural differentiation of NCCs is mediated by the miR-34a through targeting Atg9a.

MiR-34c Participates in Diabetic Corneal Neuropathy Via Regulation of Autophagy

Purpose

To investigate the contribution and mechanism of miRNAs and autophagy in diabetic peripheral neuropathy.

Methods

In this study, we used streptozotocin (STZ)-induced type I diabetes C57 mice as animal models, and we detected the expression of miR-34c and autophagic intensity in trigeminal ganglion (TG) tissue. The bioinformatics software was used to predict and analyze the potential targets of miR-34c. Primary trigeminal ganglion neurons were cultured in vitro to investigate the effect of miR-34c on axon growth and survival of TG cells. A corneal epithelial damage-healing model was established on the diabetic mice, then miR-34c antagomir was injected subconjunctivally. The condition of corneal epithelial healing was observed through sodium fluorescein staining, and the peripheral nerve degeneration of the cornea was evaluated by β-tublin corneal nerve staining.

Results

The expression of miR-34c was significantly increased in TG tissue of type I diabetic mice by real-time PCR. Western blot showed that autophagy-related proteins Atg4B and LC3-II were significantly down-regulated in diabetes TG compared with normal control. Trigeminal neuron immunofluorescence showed that the length of the trigeminal ganglion cell synapses was significantly increased after miR-34c antagomir treatment compared with normal cultures. Subconjunctival injection of miR-34c antagomir can significantly promote corneal epithelium healing of diabetic mice and appreciably promote the regeneration of corneal nerve. At the same time, it can significantly increase the expression of autophagy in TG tissue of type I diabetic mice.

Conclusions

In this study , miR-34c was found to affect the growth of trigeminal sensory neurons and the repair of diabetic corneal nerve endings by acting directly on Atg4B.

Slowing Down Ageing: The Role of Nutrients and Microbiota in Modulation of the Epigenome

The human population is getting ageing. Both ageing and age-related diseases are correlated with an increased number of senescent cells in the organism. Senescent cells do not divide but are metabolically active and influence their environment by secreting many proteins due to a phenomenon known as senescence associated secretory phenotype (SASP). Senescent cells differ from young cells by several features. They possess more damaged DNA, more impaired mitochondria and an increased level of free radicals that cause the oxidation of macromolecules. However, not only biochemical and structural changes are related to senescence. Senescent cells have an altered chromatin structure, and in consequence, altered gene expression. With age, the level of heterochromatin decreases, and less condensed chromatin is more prone to DNA damage. On the one hand, some gene promoters are easily available for the transcriptional machinery; on the other hand, some genes are more protected (locally increased level of heterochromatin). The structure of chromatin is precisely regulated by the epigenetic modification of DNA and posttranslational modification of histones. The methylation of DNA inhibits transcription, histone methylation mostly leads to a more condensed chromatin structure (with some exceptions) and acetylation plays an opposing role. The modification of both DNA and histones is regulated by factors present in the diet. This means that compounds contained in daily food can alter gene expression and protect cells from senescence, and therefore protect the organism from ageing. An opinion prevailed for some time that compounds from the diet do not act through direct regulation of the processes in the organism but through modification of the physiology of the microbiome. In this review we try to explain the role of some food compounds, which by acting on the epigenetic level might protect the organism from age-related diseases and slow down ageing. We also try to shed some light on the role of microbiome in this process.

Non-Coding RNAs in Caenorhabditis elegans Aging

Non-coding RNAs (ncRNAs) comprise various RNA species, including small ncRNAs and long ncRNAs (lncRNAs). ncRNAs regulate various cellular processes, including transcription and translation of target messenger RNAs. Recent studies also indicate that ncRNAs affect organismal aging and conversely aging influences ncRNA levels. In this review, we discuss our current understanding of the roles of ncRNAs in aging and longevity, focusing on recent advances using the roundworm Caenorhabditis elegans. Expression of various ncRNAs, including microRNA (miRNA), tRNA-derived small RNA (tsRNA), ribosomal RNA (rRNA), PIWI-interacting RNA (piRNA), circular RNA (circRNA), and lncRNA, is altered during aging in C. elegans. Genetic modulation of specific ncRNAs affects longevity and aging rates by modulating established aging-regulating protein factors. Because many aging-regulating mechanisms in C. elegans are evolutionarily conserved, these studies will provide key information regarding how ncRNAs modulate aging and lifespan in complex organisms, including mammals.

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.

MicroRNAs as Potential Pharmaco-targets in Ischemia-Reperfusion Injury Compounded by Diabetes

BACKGROUND

Ischemia-Reperfusion (I/R) injury is the tissue damage that results from re-oxygenation of ischemic tissues. There are many players that contribute to I/R injury. One of these factors is the family of microRNAs (miRNAs), which are currently being heavily studied. This review aims to critically summarize the latest papers that attributed roles of certain miRNAs in I/R injury, particularly in diabetic conditions and dissect their potential as novel pharmacologic targets in the treatment and management of diabetes.

METHODS

PubMed was searched for publications containing microRNA and I/R, in the absence or presence of diabetes. All papers that provided sufficient evidence linking miRNA with I/R, especially in the context of diabetes, were selected. Several miRNAs are found to be either pro-apoptotic, as in the case of miR-34a, miR-144, miR-155, and miR-200, or anti-apoptotic, as in the case of miR-210, miR-21, and miR-146a. Here, we further dissect the evidence that shows diverse cell-context dependent effects of these miRNAs, particularly in cardiomyocytes, endothelial, or leukocytes. We also provide insight into cases where the possibility of having two miRNAs working together to intensify a given response is noted.

CONCLUSIONS

This review arrives at the conclusion that the utilization of miRNAs as translational agents or pharmaco-targets in treating I/R injury in diabetic patients is promising and becoming increasingly clearer.

Molecular biomarkers in cardiac hypertrophy

Cardiac hypertrophy is characterized by an increase in myocyte size in the absence of cell division. This condition is thought to be an adaptive response to cardiac wall stress resulting from the enhanced cardiac afterload. The pathogenesis of heart dysfunction, which is one of the primary causes of morbidity and mortality in elderly people, is often associated with myocardial remodelling caused by cardiac hypertrophy. In order to well understand the potential mechanisms, we described the molecules involved in the development and progression of myocardial hypertrophy. Increasing evidence has indicated that micro‐RNAs are involved in the pathogenesis of cardiac hypertrophy. In addition, molecular biomarkers including vascular endothelial growth factor B, NAD‐dependent deacetylase sirtuin‐3, growth/differentiation factor 15 and glycoprotein 130, also play important roles in the development of myocardial hypertrophy. Knowing the regulatory mechanisms of these biomarkers in the heart may help identify new molecular targets for the treatment of cardiac hypertrophy.

Non-coding RNAs and Autophagy

Autophagy is an important metabolic pathway of cells. Cells degrade harmful intracellular components with the aid of autophagy to maintain a healthy state. In recent decades, the study of non-coding RNA in the regulation of autophagy has been a hot area. Mounting evidence indicates that many ncRNAs are involved in the dynamic process of autophagy, and further studies were undertaken to dissect the detailed cellular and molecular mechanisms underlying this process. In this chapter, we mainly summarized the regulation of different non-coding RNAs in autophagy as well as the detailed mechanisms. Based on these findings, we also discussed the roles of non-coding RNAs in the diagnosis, treatment, and prognosis of diseases with an emphasis on their use as potential biomarkers and therapeutic targets for different diseases.

Enoxacin extends lifespan of C. elegans by inhibiting miR-34-5p and promoting mitohormesis

Alterations in microRNA (miRNA) processing have been previously linked to aging. Here we used the small molecule enoxacin to pharmacologically interfere with miRNA biogenesis and study how it affects aging in C. elegans. Enoxacin extended worm lifespan and promoted survival under normal and oxidative stress conditions. Enoxacin-induced longevity required the transcription factor SKN-1/Nrf2 and was blunted by the antioxidant N-acetyl-cysteine, suggesting a prooxidant-mediated mitohormetic response. The longevity effects of enoxacin were also dependent on the miRNA pathway, consistent with changes in miRNA expression elicited by the drug. Among these differentially expressed miRNAs, the widely conserved miR-34-5p was found to play an important role in enoxacin-mediated longevity. Enoxacin treatment down-regulated miR-34-5p and did not further extend lifespan of long-lived mir-34 mutants. Moreover, N-acetyl-cysteine abrogated mir-34(gk437)-induced longevity. Evidence also points to double-stranded RNA-specific adenosine deaminases (ADARs) as new targets of enoxacin since ADAR loss-of-function abrogates enoxacin-induced lifespan extension. Thus, enoxacin increases lifespan by reducing miR-34-5p levels, interfering with the redox balance and promoting healthspan.

MicroRNAs in Cardiac Autophagy: Small Molecules and Big Role

Autophagy, which is an evolutionarily conserved process according to the lysosomal degradation of cellular components, plays a critical role in maintaining cell homeostasis. Autophagy and mitochondria autophagy (mitophagy) contribute to the preservation of cardiac homeostasis in physiological settings. However, impaired or excessive autophagy is related to a variety of diseases. Recently, a close link between autophagy and cardiac disorders, including myocardial infarction, cardiac hypertrophy, cardiomyopathy, cardiac fibrosis, and heart failure, has been demonstrated. MicroRNAs (miRNAs) are a class of small non-coding RNAs with a length of approximately 21–22 nucleotides (nt), which are distributed widely in viruses, plants, protists, and animals. They function in mediating the post-transcriptional gene silencing. A growing number of studies have demonstrated that miRNAs regulate cardiac autophagy by suppressing the expression of autophagy-related genes in a targeted manner, which are involved in the pathogenesis of heart diseases. This review summarizes the role of microRNAs in cardiac autophagy and related cardiac disorders. Furthermore, we mainly focused on the autophagy regulation pathways, which consisted of miRNAs and their targeted genes.

Autophagy as a promoter of longevity: insights from model organisms

Autophagy is a conserved process that catabolizes intracellular components to maintain energy homeostasis and to protect cells against stress. Autophagy has crucial roles during development and disease, and evidence accumulated over the past decade indicates that autophagy also has a direct role in modulating ageing. In particular, elegant studies using yeasts, worms, flies and mice have demonstrated a broad requirement for autophagy-related genes in the lifespan extension observed in a number of conserved longevity paradigms. Moreover, several new and interesting concepts relevant to autophagy and its role in modulating longevity have emerged. First, select tissues may require or benefit from autophagy activation in longevity paradigms, as tissue-specific overexpression of single autophagy genes is sufficient to extend lifespan. Second, selective types of autophagy may be crucial for longevity by specifically targeting dysfunctional cellular components and preventing their accumulation. And third, autophagy can influence organismal health and ageing even non-cell autonomously, and thus, autophagy stimulation in select tissues can have beneficial, systemic effects on lifespan. Understanding these mechanisms will be important for the development of approaches to improve human healthspan that are based on the modulation of autophagy.

Recent Molecular Genetic Explorations of Caenorhabditis elegans MicroRNAs

MicroRNAs are small, noncoding RNAs that regulate gene expression at the post-transcriptional level in essentially all aspects of Caenorhabditis elegans biology. More than 140 genes that encode microRNAs in C. elegans regulate development, behavior, metabolism, and responses to physiological and environmental changes. Genetic analysis of C. elegans microRNA genes continues to enhance our fundamental understanding of how microRNAs are integrated into broader gene regulatory networks to control diverse biological processes, including growth, cell division, cell fate determination, behavior, longevity, and stress responses. As many of these microRNA sequences and the related processing machinery are conserved over nearly a billion years of animal phylogeny, the assignment of their functions via worm genetics may inform the functions of their orthologs in other animals, including humans. In vivo investigations are especially important for microRNAs because in silico extrapolation of their functions using mRNA target prediction programs can easily assign microRNAs to incorrect genetic pathways. At this mezzanine level of microRNA bioinformatic sophistication, genetic analysis continues to be the gold standard for pathway assignments.

Analysis of the microRNA expression profiles in DEF cells infected with duck Tembusu virus

Duck Tembusu virus (DTMUV), belonging to the Flaviviridae family, is a single-stranded positive-sense RNA virus. Since April 2010, the outbreak of DTMUV in southeast provinces of China has caused great economic losses. MicroRNAs (miRNAs) play important regulatory roles in viral infection through binding to the host target genes or the viral genomes. To better understanding the molecular mechanisms of virus-host interaction, here we identified the miRNA expression profiles in DTMUV-infected and uninfected DEF cells by high-throughput sequencing. A total of 287 known and 63 novel miRNAs were identified. 48 miRNAs, including 26 known miRNAs and 22 novel miRNAs, were differentially expressed in response to DTMUV infection. Among these miRNAs, 37 miRNAs were up-regulated and 11 miRNAs were down-regulated. 9 miRNAs were randomly selected for validation by qRT-PCR experiment. The results of qRT-PCR experiment were consistent with the sequencing data. GO enrichment showed that the predicted targets of these differentially expressed miRNAs were mainly involved in the regulation of immune system, cellular process and metabolic process. KEGG pathways analysis showed that predicted target genes were involved in several signaling pathways such as Wnt signaling pathway, TGF-beta signaling pathway, mTOR signaling pathway and FoxO signaling pathway. This is the first study to evaluate changes of miRNA expression in DEF cells upon DTMUV infection. Our findings provide important clues for better understanding the DTMUV-host interaction.