Senescence-associated miR-34a and miR-126 in middle-aged Indians with type 2 diabetes

Swimming alleviates myocardial fibrosis of type II diabetic rats through activating miR-34a-mediated SIRT1/PGC-1α/FNDC5 signal pathway

Myocardial fibrosis can trigger heart failure in diabetic cardiomyopathy (DCM), and irisin, an exercise-induced myokine, may have a beneficial effect on cardiac function. However, the specific molecular mechanism between exercise and irisin in the diabetic heart remains not fully explored. This study aimed to investigate how miR-34a mediates exercise-induced irisin to ameliorate myocardial fibrosis and its underlying mechanisms. Type 2 diabetes mellitus (T2DM) with DCM was induced in adult male rats with high-fat diet and streptozotocin injection. The DCM rats were subjected to swimming (60 min/d) and recombinant irisin (r-irisin, 500 μg/kg/d) interventions for 8 weeks, respectively. Cardiac function, cardiomyocyte structure, myocardial fibrosis and its correlated gene and protein expression were analyzed. Swimming intervention alleviated insulin resistance, myocardial fibrosis, and myocardial hypertrophy, and promoted blood glucose homeostasis in T2DM model rats. This improvement was associated with irisin upregulation and miR-34a downregulation in the myocardium, thus enhancing cardiac function. Similar efficacy was observed via intraperitoneal injection of exogenous recombinant irisin. Inhibition of miR-34a in vivo exhibited an anti-myocardial fibrotic effect by promoting irisin secretion through activating sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α)/fibronectin type III domain-containing protein 5 (FNDC5) signal pathway and downregulating myocardial fibrosis markers (collagen I, collagen III, and transforming growth factor-β1). Therefore, swimming-induced irisin has the potential therapeutic effect on diabetic myocardial fibrosis through activating the miR-34a-mediated SIRT1/PGC-1α/FNDC5 signal pathway.

Human Aging and Age-Related Diseases: From Underlying Mechanisms to Pro-Longevity Interventions

As human life expectancy continues to rise, becoming a pressing global concern, it brings into focus the underlying mechanisms of aging. The increasing lifespan has led to a growing elderly population grappling with age-related diseases (ARDs), which strains healthcare systems and economies worldwide. While human senescence was once regarded as an immutable and inexorable phenomenon, impervious to interventions, the emerging field of geroscience now offers innovative approaches to aging, holding the promise of extending the period of healthspan in humans. Understanding the intricate links between aging and pathologies is essential in addressing the challenges presented by aging populations. A substantial body of evidence indicates shared mechanisms and pathways contributing to the development and progression of various ARDs. Consequently, novel interventions targeting the intrinsic mechanisms of aging have the potential to delay the onset of diverse pathological conditions, thereby extending healthspan. In this narrative review, we discuss the most promising methods and interventions aimed at modulating aging, which harbor the potential to mitigate ARDs in the future. We also outline the complexity of senescence and review recent empirical evidence to identify rational strategies for promoting healthy aging.

Aging and Metabolic Reprogramming of Adipose-Derived Stem Cells Affect Molecular Mechanisms Related to Cardiovascular Diseases

We performed a systematic search of the PubMed database for English-language articles related to the function of adipose-derived stem cells in the pathogenesis of cardiovascular diseases. In preclinical models, adipose-derived stem cells protected arteries and the heart from oxidative stress and inflammation and preserved angiogenesis. However, clinical trials did not reiterate successful treatments with these cells in preclinical models. The low success in patients may be due to aging and metabolic reprogramming associated with the loss of proliferation capacity and increased senescence of stem cells, loss of mitochondrial function, increased oxidative stress and inflammation, and adipogenesis with increased lipid deposition associated with the low potential to induce endothelial cell function and angiogenesis, cardiomyocyte survival, and restore heart function. Then, we identify noncoding RNAs that may be mechanistically related to these dysfunctions of human adipose-derived stem cells. In particular, a decrease in let-7, miR-17-92, miR-21, miR-145, and miR-221 led to the loss of their function with obesity, type 2 diabetes, oxidative stress, and inflammation. An increase in miR-34a, miR-486-5p, and mir-24-3p contributed to the loss of function, with a noteworthy increase in miR-34a with age. In contrast, miR-146a and miR-210 may protect stem cells. However, a systematic analysis of other noncoding RNAs in human adipose-derived stem cells is warranted. Overall, this review gives insight into modes to improve the functionality of human adipose-derived stem cells.

MicroRNA-34a Mediates High-Fat-Induced Hepatic Insulin Resistance by Targeting ENO3

The etiology of numerous metabolic disorders is characterized by hepatic insulin resistance (IR). Uncertainty surrounds miR-34a's contribution to high-fat-induced hepatic IR and its probable mechanism. The role and mechanism of miR-34a and its target gene ENO3 in high-fat-induced hepatic IR were explored by overexpressing/suppressing miR-34a and ENO3 levels in in vivo and in vitro experiments. Moreover, as a human hepatic IR model, the miR-34a/ENO3 pathway was validated in patients with non-alcoholic fatty liver disease (NAFLD). The overexpression of hepatic miR-34a lowered insulin signaling and altered glucose metabolism in hepatocytes. In contrast, reducing miR-34a expression significantly reversed hepatic IR indices induced by palmitic acid (PA)/HFD. ENO3 was identified as a direct target gene of miR-34a. Overexpression of ENO3 effectively inhibited high-fat-induced hepatic IR-related indices both in vitro and in vivo. Moreover, the expression patterns of members of the miR-34a/ENO3 pathway in the liver tissues of NAFLD patients was in line with the findings of both cellular and animal studies. A high-fat-induced increase in hepatic miR-34a levels attenuates insulin signaling and impairs glucose metabolism by suppressing the expression of its target gene ENO3, ultimately leading to hepatic IR. The miR-34a/ENO3 pathway may be a potential therapeutic target for hepatic IR and related metabolic diseases.

Therapeutic actions of tea phenolic compounds against oxidative stress and inflammation as central mediators in the development and progression of health problems: A review focusing on microRNA regulation

Many health problems including chronic diseases are closely associated with oxidative stress and inflammation. Tea has abundant phenolic compounds with various health benefits including antioxidant and anti-inflammatory properties. This review focuses on the present understanding of the impact of tea phenolic compounds on the expression of miRNAs, and elucidates the biochemical and molecular mechanisms underlying the transcriptional and post-transcriptional protective actions of tea phenolic compounds against oxidative stress- and/or inflammation-mediated diseases. Clinical studies showed that drinking tea or taking catechin supplement on a daily basis promoted the endogenous antioxidant defense system of the body while inhibiting inflammatory factors. The regulation of chronic diseases based on epigenetic mechanisms, and the epigenetic-based therapies involving different tea phenolic compounds, have been insufficiently studied. The molecular mechanisms and application strategies of miR-27 and miR-34 involved in oxidative stress response and miR-126 and miR-146 involved in inflammation process were preliminarily investigated. Some emerging evidence suggests that tea phenolic compounds may promote epigenetic changes, involving non-coding RNA regulation, DNA methylation, histone modification, ubiquitin and SUMO modifications. However, epigenetic mechanisms and epigenetic-based disease therapies involving phenolic compounds from different teas, and the potential cross-talks among the epigenetic events, remain understudied.

Metformin regulates chondrocyte senescence and proliferation through microRNA-34a/SIRT1 pathway in osteoarthritis

BACKGROUND

Osteoarthritis (OA) is the most common degenerative disease in joints among elderly patients. Senescence is deeply involved in the pathogenesis of osteoarthritis. Metformin is widely used as the first-line drug for Type 2 diabetes mellitus (T2DM), and has great potential for the treatment of other aging-related disorders, including OA. However, the role of metformin in OA is not fully elucidated. Therefore, our aim here was to investigate the effects of metformin on human chondrocytes.

METHODS

After metformin treatment, expression level of microRNA-34a and SIRT1 in chondrocyte were detected with quantitative real-time PCR and immunofluorescence staining. Then, microRNA-34a mimic and small interfering RNA (siRNA) against SIRT1 (siRNA-SIRT1) were transfected into chondrocyte. Senescence-associated β-galactosidase (SA-β-gal) staining was performed to assess chondrocyte senescence. Chondrocyte viability was illustrated with MTT and colony formation assays. Western blot was conducted to detect the expression of P16, IL-6, matrix metalloproteinase-13 (MMP-13), Collagen type II (COL2A1) and Aggrecan (ACAN).

RESULTS

We found that metformin treatment (1 mM) inhibited microRNA-34a while promoted SIRT1 expression in OA chondrocytes. Both miR-34a mimics and siRNA against SIRT1 inhibited SIRT1 expression in chondrocytes. SA-β-gal staining assay confirmed that metformin reduced SA-β-gal-positive rate of chondrocytes, while transfection with miR-34a mimics or siRNA-SIRT1 reversed it. MTT assay and colony formation assay showed that metformin accelerated chondrocyte proliferation, while miR-34a mimics or siRNA-SIRT1 weakened this effect. Furthermore, results from western blot demonstrated that metformin suppressed expression of senescence-associated protein P16, proinflammatory cytokine IL-6 and catabolic gene MMP-13 while elevated expression of anabolic proteins such as Collagen type II and Aggrecan, which could be attenuated by transfection with miR-34a mimics.

CONCLUSION

Overall, our data suggest that metformin regulates chondrocyte senescence and proliferation through microRNA-34a/SIRT1 pathway, indicating it could be a novel strategy for OA treatment.

MicroRNAs as Biomarkers for Coronary Artery Disease Related to Type 2 Diabetes Mellitus-From Pathogenesis to Potential Clinical Application

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with still growing incidence among adults and young people worldwide. Patients with T2DM are more susceptible to developing coronary artery disease (CAD) than non-diabetic individuals. The currently used diagnostic methods do not ensure the detection of CAD at an early stage. Thus, extensive research on non-invasive, blood-based biomarkers is necessary to avoid life-threatening events. MicroRNAs (miRNAs) are small, endogenous, non-coding RNAs that are stable in human body fluids and easily detectable. A number of reports have highlighted that the aberrant expression of miRNAs may impair the diversity of signaling pathways underlying the pathophysiology of atherosclerosis, which is a key player linking T2DM with CAD. The preclinical evidence suggests the atheroprotective and atherogenic influence of miRNAs on every step of T2DM-induced atherogenesis, including endothelial dysfunction, endothelial to mesenchymal transition, macrophage activation, vascular smooth muscle cells proliferation/migration, platelet hyperactivity, and calcification. Among the 122 analyzed miRNAs, 14 top miRNAs appear to be the most consistently dysregulated in T2DM and CAD, whereas 10 miRNAs are altered in T2DM, CAD, and T2DM-CAD patients. This up-to-date overview aims to discuss the role of miRNAs in the development of diabetic CAD, emphasizing their potential clinical usefulness as novel, non-invasive biomarkers and therapeutic targets for T2DM individuals with a predisposition to undergo CAD.

Current Insights into miRNA and lncRNA Dysregulation in Diabetes: Signal Transduction, Clinical Trials and Biomarker Discovery

Diabetes is one of the most frequently occurring metabolic disorders, affecting almost one tenth of the global population. Despite advances in antihyperglycemic therapeutics, the management of diabetes is limited due to its complexity and associated comorbidities, including diabetic neuropathy, diabetic nephropathy and diabetic retinopathy. Noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), are involved in the regulation of gene expression as well as various disease pathways in humans. Several ncRNAs are dysregulated in diabetes and are responsible for modulating the expression of various genes that contribute to the 'symptom complex' in diabetes. We review various miRNAs and lncRNAs implicated in diabetes and delineate ncRNA biological networks as well as key ncRNA targets in diabetes. Further, we discuss the spatial regulation of ncRNAs and their role(s) as prognostic markers in diabetes. We also shed light on the molecular mechanisms of signal transduction with diabetes-associated ncRNAs and ncRNA-mediated epigenetic events. Lastly, we summarize clinical trials on diabetes-associated ncRNAs and discuss the functional relevance of the dysregulated ncRNA interactome in diabetes. This knowledge will facilitate the identification of putative biomarkers for the therapeutic management of diabetes and its comorbidities. Taken together, the elucidation of the architecture of signature ncRNA regulatory networks in diabetes may enable the identification of novel biomarkers in the discovery pipeline for diabetes, which may lead to better management of this metabolic disorder.

Effect of diabetes on efferocytosis process

Diabetes is a complex of genetic, metabolic, and autoimmune disorders that are characterized by hyperglycemia. Elevated apoptotic cell count following defective clearance of dead cells that can cause chronic inflammation is a hallmark of the diabetic wound. Effective dead cell clearance is a prerequisite for rapid inflammation resolution and successful recovery. Efferocytosis is a multistep process in which phagocytes engulf the dead cells. Cell body elimination is of great significance in disease and homeostasis. Recent research has clarified that diabetic wounds have an enhanced load of the apoptotic cell, which is partly attributed to the dysfunction of macrophages in apoptotic clearance at the site of the diabetic wounds. In the current work, we highlight the pathways implicated in efferocytosis, from the diagnosis of apoptotic cells to the phagocytic swallowing and the homeostatic resolution, and explain the possible pathophysiological episodes occurring when the proceeding is abrogated. Also, we describe the last development in the management of inflammation in diabetes wound and future directions of surveillance.

Emerging Role of Non-Coding RNAs in Senescence

Senescence is defined as a gradual weakening of functional features of a living organism. Cellular senescence is a process that is principally aimed to remove undesirable cells by prompting tissue remodeling. This process is also regarded as a defense mechanism induced by cellular damage. In the course of oncogenesis, senescence can limit tumor progression. However, senescence participates in the pathoetiology of several disorders such as fibrotic disorders, vascular disorders, diabetes, renal disorders and sarcopenia. Recent studies have revealed contribution of different classes of non-coding RNAs in the cellular senescence. Long non-coding RNAs, microRNAs and circular RNAs are three classes of these transcripts whose contributions in this process have been more investigated. In the current review, we summarize the available literature on the impact of these transcripts in the cellular senescence.

MicroRNAs and Efferocytosis: Implications for Diagnosis and Therapy

About 10-100 billion cells are generated in the human body in a day, and accordingly, 10-100 billion cells predominantly die for maintaining homeostasis. Dead cells generated by apoptosis are also rapidly engulfed by macrophages (Mθs) to be degraded. In case of the inefficient engulfment of apoptotic cells (ACs) via Mθs, they experience secondary necrosis and thus release intracellular materials, which display damage-associated molecular patterns (DAMPs) and result in diseases. Over the last decades, researchers have also reflected on the significant contribution of microRNAs (miRNAs) to autoimmune diseases through the regulation of Mθs functions. Moreover, miRNAs have shown intricate involvement with completely adjusting basic Mθs functions, such as phagocytosis, inflammation, efferocytosis, tumor promotion, and tissue repair. In this review, the mechanism of efferocytosis containing "Find-Me", "Eat-Me", and "Digest-Me" signals is summarized and the biogenesis of miRNAs is briefly described. Finally, the role of miRNAs in efferocytosis is discussed. It is concluded that miRNAs represent promising treatments and diagnostic targets in impaired phagocytic clearance, which leads to different diseases.

Overexpression of miR-126 Protects Hypoxic-Reoxygenation-Exposed HUVEC Cellular Injury through Regulating LRP6 Expression

The aim of the study was to explore the clinical impact of circulatory miR-126 as a candidate for novel biomarker in patients with coronary artery disease (CAD) and its protective role against hypoxia/reoxygenation- (H/R-) exposed HUVEC cellular injury. A total of 278 subjects, which included 153 subjects with angiographically confirmed CAD, 70 unstable angina subjects, and 55 healthy individuals, along with 18-hour HR-induced HUVECs were recruited in this study. Plasma miR-126 levels were significantly downregulated in stable and unstable CAD patients as well as 18-hour HR-exposed HUVECs as compared with controls. Stable and unstable CAD subjects were significantly differentiated from healthy individuals with a predictive value of AUC 0.903 and 0.923, respectively. Moreover, peripheral circulatory miR-126 expressions in elderly (71-90 years) stable and unstable CAD patients were comparatively lower than younger (30-50 years) subjects. The caspase-3 activity, intracellular ROS concentrations, and cellular viabilities were evidently increased in 18-hour HR-exposed HUVECs than in normal cells ( $P<0.001$ ). On the contrary, mimic expressions of miR-126 prominently reduced caspase-3 activity and intracellular ROS levels and markedly enhanced HUVEC cellular viabilities ( $P<0.001$ ). LRP6 expressions were significantly elevated in HR-induced HUVECs, whereas overexpression of miR-126 remarkably decreased LRP6 expressions ( $P<0.001$ ). Plasma miR-126 could be used as a novel biomarker for early prediction of CAD subjects. Overexpression of miR-126 significantly improved HUVEC cellular viabilities by downregulation of LRP6 protein expression, suggesting a potential therapeutic target for CAD patients.

miR-34a attenuates myocardial fibrosis in diabetic cardiomyopathy mice via targeting Pin-1

Diabetic cardiomyopathy (DCM) is characterized by myocardial hypertrophy and fibrosis. This study aimed to investigate the effects of microRNA (miR)-34a on myocardial fibrosis in DCM and its potential mechanism of targeting Pin-1 signaling. Vimentin and Pin-1 proteins in mouse cardiac tissues were detected by immunohistochemical staining. Locked nucleic acid in situ hybridization was used to measure miR-34a expression in cardiac tissues. Primary mouse cardiac fibroblasts (CFs) were transfected with a mimics control/miR-34a mimics or Pin-1 plasmid and cultured in high-glucose (HG) Dulbecco's modified Eagle's medium. The miR-34a levels were measured by quantitative polymerase chain reaction. The apoptosis and viability of transfected cells were detected by the terminal deoxynucleotidyl transferase dUTP nick end labeling and Cell Counting Kit-8 assays respectively. A cell migration experiment and dual-luciferase reporter assay were also performed. The body weight and fasting blood glucose of DCM mice were significantly higher than those in the control (CTL) group. In addition, DCM mice had decreased serum insulin levels and impaired cardiac function. The number of CFs in the DCM group was higher than in the CTL group and Pin-1 expression was upregulated. The expression level of miR-34a in the cardiac tissue of mice in the DCM group was obviously downregulated compared with the CTL group. The HG stimulation of CFs for 48 h significantly downregulated the expression level of miR-34a and was associated with increased Type I collagen expression, cell viability, and migration and decreased apoptosis. However, these effects could be reversed by overexpressing miR-34a in HG-induced CFs. Furthermore, we found that Pin-1 was a direct target of miR-34a. Our results suggest that miR-34a can attenuate myocardial fibrosis in DCM by reducing Type I collagen production, cell viability, and migration and increasing the apoptosis of CFs by targeting Pin-1 signaling.

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.

The current state of MiRNAs as biomarkers and therapeutic tools

MicroRNAs (miRNAs) are non-coding RNAs with a length of 18-22 nucleotides that regulate about a third of the human genome at the post-transcriptional level. MiRNAs are involved in almost all biological processes, including cell proliferation, apoptosis, and cell differentiation, but also play a key role in the pathogenesis of many diseases. Most miRNAs are expressed within the cells themselves. Due to various forms of transport from cells like exosomes, circulating miRNAs are stable and can be found in human body fluids, such as blood, saliva, cerebrospinal fluid, and urine. Circulating miRNAs are of great interest as potential noninvasive biomarkers for tumors, lipid disorders, diabetes mellitus, and cardiovascular diseases. However, the possibility of their use in the clinic is limited, and this is associated with a number of problems since currently there are significant differences between the procedures for processing samples, methods of analysis, and especially strategies for standardizing results. Moreover, miRNAs can represent not only potential biomarkers but also become new therapeutic agents and be used in modern clinical practice, which again confirms the need for their study.