miR-146a-5p Mediates Intermittent Hypoxia-Induced Injury in H9c2 Cells by Targeting XIAP

Advances in non-coding RNA as a biomarker for obstructive sleep apnoea hypoventilation syndrome

PURPOSE

Obstructive sleep apnoea hypoventilation syndrome (OSAHS) is a common sleep disorder that affects multiple body systems, which in turn is closely associated with cognitive dysfunction, diabetes mellitus, oncological cardiovascular diseases and metabolic disorders. In recent years, non-coding RNA (ncRNA) has emerged as a new opportunity for biomarker discovery. We therefore discuss the research progress and potential role of ncRNAs in obstructive sleep apnea hypoventilation syndrome.

METHODS

This review systematically searched relevant academic literature from PubMed, Web of Science and other databases. During the retrieval process, a combination of keywords such as "OSAHS", "ncRNA", "lncRNA", "miRAN", "circRNA" was used for search.

RESULTS

Circulating ncRNA has good area under the ROC curve, sensitivity and specificity in the diagnosis of OSAHS, and has the potential to become a diagnostic marker for OSAHS, while several circulating ncRNAs or circulating ncRNAs in combination with other tests such as the Obstructive Sleep Apnoea Screening Scale have a higher value of application as a test for OSAHS. Further analyses revealed that many circulating ncRNAs were significantly differentially expressed in the serum of OSAHS patients with different very severities, a potential marker for predicting the severity of OSAHS, and that the ncRNA content of patients' serum also had a significant effect during CPAP therapy, suggesting that it may have potential for therapeutic monitoring. Meanwhile, serum ncRNAs from patients have been shown to be effective in the diagnosis of OSAHS complications such as hypertension, Alzheimer's disease, acute myocardial infarction and atherosclerosis. The expression of up- or down-regulated ncRNAs can regulate different signalling pathways, which in turn affects various OSAHS complications such as pulmonary hypertension, diabetes mellitus, and cognitive dysfunction, and is expected to become a new direction for the treatment of these complications.

CONCLUSIONS

The changes in ncRNA expression in OSAHS patients are expected to be a novel biomarker for the diagnosis and treatment of OSAHS, and can also be used as a potential biomarker for the combination of diabetes mellitus, cardiovascular disease, respiratory disease, and cognitive dysfunction in OSAHS. It is believed that the continuous progress of ncRNA-related research is expected to promote the early detection, diagnosis and treatment of OSAHS and its complications.

METTL14-mediated N6-methyladenosine modification induces the ferroptosis of hypoxia/reoxygenation-induced cardiomyocytes

BACKGROUND

Hypoxia/reoxygenation (H/R) induces cardiomyocyte ferroptosis, a core remodeling event in myocardial ischemia/reperfusion injury. Methyltransferase-like 14 (METTL14) emerges as a writer of N6-methyladenosine (m6A) modification. This study was conducted to decipher the role of METTL14 in H/R-induced cardiomyocyte ferroptosis.

METHODS

Mouse cardiomyocytes HL-1 were cultured and underwent H/R treatment. The degree of ferroptosis after H/R treatment was appraised by the cell counting kit-8 assay, assay kits (ROS/GSH/Fe2+), and Western blotting (GPX4/ACSL4). The intracellular expressions of METTL14, pri-miR-146a-5p, miR-146a-5p, or adaptor protein phosphotyrosine interacting with PH domain and leucine zipper 1 (APPL1) were examined by real-time quantitative polymerase chain reaction or Western blotting, with m6A quantification analysis and RNA immunoprecipitation to determine the total m6A level and the expression of pri-miR-146a-5p bound to DiGeorge critical region 8 (DGCR8) and m6A-modified pri-miR-146a-5p. The binding of miR-146a-5p to APPL1 was testified by the dual-luciferase assay.

RESULTS

H/R treatment induced cardiomyocyte ferroptosis (increased ROS, Fe2+, and ACSL4 and decreased GSH and GPX4) and upregulated METTL14 expression. METTL14 knockdown attenuated H/R-induced cardiomyocyte ferroptosis. METTL14 induced the recognition of pri-miR-146a-5p by DGCR8 by increasing m6A modification on pri-miR-146a-5p, which promoted the conversion of pri-miR-146a-5p into miR-146a-5p and further repressed APPL1 transcription. miR-146a-5p upregulation or APPL1 downregulation limited the inhibitory effect of METTL14 downregulation on H/R-induced cardiomyocyte ferroptosis.

CONCLUSION

METTL14 promoted miR-146a-5p expression through the recognition and processing of pri-miR-146a-5p by DGCR8, which repressed APPL1 transcription and triggered H/R-induced cardiomyocyte ferroptosis.

Effects of obstructive sleep apnea on myocardial injury and dysfunction: a review focused on the molecular mechanisms of intermittent hypoxia

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia (IH) and is strongly associated with adverse cardiovascular outcomes. Myocardial injury and dysfunction have been commonly observed in clinical practice, particularly in patients with severe OSA. However, the underlying mechanisms remain obscure. In this review, we summarized the molecular mechanisms by which IH impact on myocardial injury and dysfunction. In brief, IH-induced cardiomyocyte death proceeds through the regulation of multiple biological processes, including differentially expressed transcription factors, alternative epigenetic programs, and altered post-translational modification. Besides cell death, various cardiomyocyte injuries, such as endoplasmic reticulum stress, occurs with IH. In addition to the direct effects on cardiomyocytes, IH has been found to deteriorate myocardial blood and energy supply by affecting the microvascular structure and disrupting glucose and lipid metabolism. For better diagnosis and treatment of OSA, further studies on the molecular mechanisms of IH-induced myocardial injury and dysfunction are essential.

The role of exosomal circular RNA ZNF292 in intermittent hypoxia-induced AC16 cardiomyocytes injury

BACKGROUND

Exosomes are involved in cell-to-cell communication in numerous diseases including cardiovascular diseases, neurological diseases. Little attention has been dedicated to exosomal circular RNAs in obstructive sleep apnea (OSA)-related cardiovascular diseases. The aim of this study was to explore the role of exosomal circular RNA ZNF292 (circZNF292) on AC16 cells exposure to intermittent hypoxia (IH).

METHODS

Exosome release inhibitor GW4869 was used to examine the effect of exosomes on IH-induced AC16 cells apoptosis. The expression of exosomal circZNF292 was detected by qRT-PCR in AC16 cells exposure to IH, and a luciferase reporter assay was conducted to confirm the connection between circZNF292 and miR-146a-5p. Exosomal circZNF292 was stably transfected with short hairpin RNAs (shRNAs) against circZNF292 and co-cultured with AC16 cells. The expression of miR-146a-5p and apoptosis-related protein was then measured to evaluate the effect of exosomal circZNF292.

RESULTS

We found that IH contributed to the AC16 cells apoptosis, and the administration of GW4869 increased the apoptosis of cardiomyocytes when exposed to IH. The expression of exosomal circZNF292 decreased and miR-146a-5p increased significantly in AC16 cells exposed to IH compared to normoxic conditions. Bioinformatics analysis predicted a circZNF292/miR-146a-5p axis in IH-induced cardiomyocytes apoptosis. The dual-luciferase reporter system validated the direct interaction of circZNF292 and miR-146a-5p. Knockdown of circZNF292 increased the expressions of miR-146a-5p and accelerated the AC16 cardiomyocytes apoptosis.

CONCLUSIONS

The findings of this study suggested a novel mechanism by which exosomes transmit intrinsic regulatory signals to the myocardium through the exosomal circZNF292/miR-146a-5p axis. This finding highlights the potential of targeting this pathway as a therapeutic approach for treating cardiovascular diseases associated with OSA.

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.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

Identification of key biomarkers associated with immune cells infiltration for myocardial injury in dermatomyositis by integrated bioinformatics analysis

BACKGROUND

Dermatomyositis (DM) is an acquired autoimmune disease that can cause damage to various organs, including the heart muscle. However, the mechanisms underlying myocardial injury in DM are not yet fully understood.

METHODS

In this study, we utilized publicly available datasets from the Gene Expression Omnibus (GEO) database to identify hub-genes that are enriched in the immune system process in DM and myocarditis. Weighted gene co-expression network analysis (WGCNA), differentially expressed genes (DEGs) analysis, protein-protein interaction (PPI), and gene ontology (GO) analysis were employed to identify these hub-genes. We then used the CIBERSORT method to analyze immune cell infiltration in skeletal muscle specimens of DM and myocardium specimens of myocarditis respectively. Correlation analysis was performed to investigate the relationship between key genes and infiltrating immune cells. Finally, we predicted regulatory miRNAs of hub-genes through miRNet and validated their expression in online datasets and clinical samples.

RESULTS

Using integrated bioinformatics analysis, we identified 10 and 5 hub-genes that were enriched in the immune system process in the database of DM and myocarditis respectively. The subsequent intersections between hub-genes were IFIT3, OAS3, ISG15, and RSAD2. We found M2 macrophages increased in DM and myocarditis compared to the healthy control, associating with the expression of IFIT3, OAS3, ISG15, and RSAD2 in DM and myocarditis positively. Gene function enrichment analysis (GSEA) showed that IFIT3, OAS3, ISG15, and RSAD2 were mainly enriched in type I interferon (IFN) signaling pathway, cellular response to type I interferon, and response to type I interferon. Finally, we verified that the expression of miR-146a-5p was significantly higher in the DM with myocardial injury than those without myocardial injury (p = 0.0009).

CONCLUSION

Our findings suggest that IFIT3, OAS3, ISG15, and RSAD2 may play crucial roles in the underlying mechanism of myocardial injury in DM. Serum miR-146a-5p could be a potential biomarker for myocardial injury in DM.

Role of epigenetic abnormalities and intervention in obstructive sleep apnea target organs

ABSTRACT

Obstructive sleep apnea (OSA) is a common condition that has considerable impacts on human health. Epigenetics has become a rapidly developing and exciting area in biology, and it is defined as heritable alterations in gene expression and has regulatory effects on disease progression. However, the published literature that is integrating both of them is not sufficient. The purpose of this article is to explore the relationship between OSA and epigenetics and to offer better diagnostic methods and treatment options. Epigenetic modifications mainly manifest as post-translational modifications in DNA and histone proteins and regulation of non-coding RNAs. Chronic intermittent hypoxia-mediated epigenetic alterations are involved in the progression of OSA and diverse multiorgan injuries, including cardiovascular disease, metabolic disorders, pulmonary hypertension, neural dysfunction, and even tumors. This article provides deeper insights into the disease mechanism of OSA and potential applications of targeted diagnosis, treatment, and prognosis in OSA complications.

Molecular Pathology, Oxidative Stress, and Biomarkers in Obstructive Sleep Apnea

Obstructive sleep apnea syndrome (OSAS) is characterized by intermittent hypoxia (IH) during sleep due to recurrent upper airway obstruction. The derived oxidative stress (OS) leads to complications that do not only concern the sleep-wake rhythm but also systemic dysfunctions. The aim of this narrative literature review is to investigate molecular alterations, diagnostic markers, and potential medical therapies for OSAS. We analyzed the literature and synthesized the evidence collected. IH increases oxygen free radicals (ROS) and reduces antioxidant capacities. OS and metabolic alterations lead OSAS patients to undergo endothelial dysfunction, osteoporosis, systemic inflammation, increased cardiovascular risk, pulmonary remodeling, and neurological alterations. We treated molecular alterations known to date as useful for understanding the pathogenetic mechanisms and for their potential application as diagnostic markers. The most promising pharmacological therapies are those based on N-acetylcysteine (NAC), Vitamin C, Leptin, Dronabinol, or Atomoxetine + Oxybutynin, but all require further experimentation. CPAP remains the approved therapy capable of reversing most of the known molecular alterations; future drugs may be useful in treating the remaining dysfunctions.

LncRNA XR_595552 inhibition alleviates intermittent hypoxia-induced cardiomyocyte damage via activating the PI3K/AKT pathway

BACKGROUND

Although the long noncoding RNAs (lncRNAs) expression profiles have been observed in previous study, the biological functions and underlying mechanisms of lncRNAs in OSA-related cardiac injury have not been elucidated. In the present study, we investigated a novel lncRNA, lncRNA XR_595552, and evaluated its role in intermittent hypoxia (IH)-induced damage in H9c2 cardiomyocytes.

METHODS

H9c2 cells were exposed to IH condition. Real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to measure the expression changes of lncRNA XR_595552 in H9c2 cells stimulated by IH. H9c2 cells were subjected to IH after transfection. CCK-8 was used to evaluate cell viability, and apoptosis was analyzed by Western blotting. Additionally, the regulatory relationship between lncRNA XR_595552 and PI3K/AKT was tested by RT-qPCR and Western blot.

RESULTS

IH significantly induced injury in H9c2 cells (inhibited cell viability and promoted cell apoptosis). lncRNA XR_595552 was upregulated in a cell model of IH. Inhibition of lncRNA XR_595552 protected H9c2 cells against IH-induced damage, as the viability was increased, Bax, Caspase-9, and Caspase-3 were downregulated, and Bcl-2 was upregulated. More interestingly, lncRNA XR_595552 downregulation activated the PI3K/AKT pathway. Blocking the PI3K/AKT signal pathway by the use of LY294002 eliminated the myocardioprotective effects of lncRNA XR_595552 in H9c2 cells under IH condition.

CONCLUSIONS

The results show that lncRNA XR_595552, a novel lncRNA, may play a protective role in attenuating IH-induced injury in cardiomyocytes via a regulating PI3K/AKT pathway. The findings suggest that this lncRNA could serve as a therapeutic target to treat OSA-related cardiovascular disorders.

Research progress on the role of exosomes in obstructive sleep apnea-hypopnea syndrome-related atherosclerosis

Cardiovascular disease (CVD) is a leading cause of mortality worldwide. Atherosclerosis, a multifactorial disease with complicated pathogenesis, is the main cause of CVD, underlying several major adverse cardiovascular events. Obesity is the main cause of obstructive sleep apnea (OSA) and a significant risk for atherosclerosis. OSA is an independent risk factor for CVD. Recent research has focused on understanding the underlying molecular mechanisms by which OSA influences atherosclerosis pathogenesis. The role of exosomes in this process has attracted considerable attention. Exosomes are a type of extracellular vesicles (EV) that are released from many cells (both healthy and diseased) and mediate cell-to-cell communication by transporting microRNAs (miRNAs), proteins, mRNAs, DNA, or lipids to target cells, thereby modulating the functions of target cells and tissues. Intermittent hypoxia in OSA alters the exosomal carrier in circulation and promotes the permeability and dysfunction of endothelial cells, which have been associated with the pathogenesis of atherosclerosis. This review discusses the potential roles of exosomes and exosome-derived molecules in the development and progression of OSA-related atherosclerosis. Additionally, we explore the possible mechanisms underlying OSA-related atherosclerosis and provide new insights for the development of novel exosome-based therapeutics for OSA-related atherosclerosis and CVD.

Advances in Molecular Pathology of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common syndrome that features a complex etiology and set of mechanisms. Here we summarized the molecular pathogenesis of OSA, especially the prospective mechanism of upper? airway dilator fatigue and the current breakthroughs. Additionally, we also introduced the molecular mechanism of OSA in terms of related studies on the main signaling pathways and epigenetics alterations, such as microRNA, long non-coding RNA, and DNA methylation. We also reviewed small molecular compounds, which are potential targets for gene regulations in the future, that are involved in the regulation of OSA. This review will be beneficial to point the way for OSA research within the next decade.

Micro-RNA in obstructive sleep apnoea: biomarker of cardiovascular outcome?

PURPOSE OF REVIEW

Obstructive sleep apnoea (OSA) is a global health problem with important cardiovascular consequences. Risk assessment tools are essential in OSA to identify patients at increased risk of cardiovascular disease and to achieve a cost-effective clinical management of the disease in the era of precision medicine. The objective is to provide an updated perspective on the role of microRNAs (miRNAs) in OSA as a biomarker of cardiovascular risk.

RECENT FINDINGS

Specific miRNAs have already been associated with patients with OSA and specific cardiovascular diseases such as hypertension, myocardial infarction or endothelial dysfunction. Numerous studies have addressed the use of miRNAs to identify the cardiovascular risk associated with OSA, both in patients and in animals with in vivo hypoxia models. Thus, these studies identified profiles of differentially expressed miRNAs in patients with OSA. In addition, the in vitro studies suggest that therapies with miRNA inhibitors that could help reduce cardiovascular risk. Therefore, this review highlights the primary approaches of the potential of miRNAs as biomarkers at the prognostic, diagnostic and therapeutic strategy levels.

SUMMARY

Given the heterogeneity of OSA and its cardiovascular consequences, miRNAs have emerged as powerful biomarkers that can help improve the clinical management of OSA and its cardiovascular risk.

Bcl-2 19-kDa Interacting Protein 3 (BNIP3)-Mediated Mitophagy Attenuates Intermittent Hypoxia-Induced Human Renal Tubular Epithelial Cell Injury

Background

As a novel pathophysiological characteristic of obstructive sleep apnea, intermittent hypoxia (IH) contributes to human renal tubular epithelial cells impairment. The underlying pathological mechanisms remain unrevealed. The present study aimed to evaluate the influence of Bcl-2 19-kDa interacting protein 3 (BNIP3)-mediated mitophagy on IH-induced renal tubular epithelial cell impairment.

Material/Methods

Human kidney proximal tubular (HK-2) cells were exposed to IH condition. IH cycles were as follows: 21% oxygen for 25 min, 21% descended to 1% for 35 min, 1% oxygen sustaining for 35 min, and 1% ascended to 21% for 25 min. The IH exposure lasted 24 h with 12 cycles of hypoxia and re-oxygenation. Both the siBNIP3 and BNIP3 vector were transfected to cells. Cell viability and apoptosis, mitochondrial morphology and function, and mitophagy were detected by cell counting kit-8, flow cytometry and TUNEL staining, transmission electron microscopy, western blotting, and immunofluorescence, respectively.

Results

In the IH-induced HK-2 cells, inhibition of BNIP3 further aggravated mitochondrial structure damage, and decreased mitophagy level, leading to increased cell apoptosis and decreased cell viability. While overexpression of BNIP3 enhanced mitophagy, which protected mitochondrial structure, it can decrease cell death in HK-2 cells exposed to IH.

Conclusions

The present study showed that BNIP3-mediated mitophagy plays a protective role against IH-induced renal tubular epithelial cell impairment.

Orexin-A Reverse Bone Mass Loss Induced by Chronic Intermittent Hypoxia Through OX1R-Nrf2/HIF-1α Pathway

Background

Recent studies suggest that there is a potential connection between obstructive sleep apnea (OSA) and osteoporosis through dysregulation of bone metabolism. Orexin-A, a neuroprotective peptide secreted by the hypothalamus, is at a lower level in the plasma of OSA patients, which regulates appetite, energy expenditure and sleep-wake states. However, the protective effect of orexin-A on bone metabolism in OSA is unclear.

Purpose

To investigate whether the activation of OX1R by orexin-A can reverse bone mass loss induced by chronic intermittent hypoxia (CIH).

Methods

Mice were randomly divided into the normoxia group and CIH group. Within the CIH or normoxia groups, treatment groups were given a subcutaneous injection of either orexin-A or saline vehicle once every day for 4 weeks and then femurs were removed for micro-CT scans. Histology and immunohistochemical staining were performed to observe and calculate the changes in femurs as a result of hypoxia. Cell immunofluorescence and immunohistochemical staining were used to detect the expression of orexin receptors in MC3T3-E1 cells or in bones. CCK-8 assay, ALP assay kit and alizarin red staining were used to detect the viability, alkaline phosphatase (ALP) activity, and capacity of mineralization, respectively. The effect of orexin-A on osteogenic differentiation of MC3T3-E1 cells was evaluated using qRT-PCR, Western blot and cell staining.

Results

CIH led to a decrease in the amount and density of trabecular bone, downregulated OCN expression while increasing osteoclast numbers in femurs and inhibited the expression of RUNX2, OSX, OPN and Nrf2 in MC3T3-E1 cells. Orexin-A treatment alleviated these CIH-induced effects by combining to OX1R. The level of HIF-1α was elevated both in CIH and orexin-A treatment groups.

Conclusion

CIH environment inhibits osteogenesis and orexin-A can reverse bone mass loss induced by CIH through OX1R-Nrf2/HIF-1α pathway.

MicroRNA-577 aggravates bone loss and bone remodeling by targeting thyroid stimulating hormone receptor in hyperthyroid-associated osteoporosis

Traditionally, hyperthyroid-associated osteoporosis has been considered to be the result of increased thyroid hormone levels. The pathogenesis of hyperthyroid-associated osteoporosis remains unclear. Thyroid stimulating hormone receptor (TSHR) is closely associated with osteoporosis. Our study aimed to explore the role of TSHR and its upstream microRNA (miRNA) in hyperthyroid-associated osteoporosis. Bioinformatics analysis (starBase and Targetscan) and a wide range of experiments including reverse-transcription quantitative polymerase chain reaction, luciferase reporter, western blot analysis of osteogenic differentiation markers including OSX, OCN, ALP, OPN, and COL1, hematoxylin and eosin staining, Alizarin Red staining assays were used to explore the function and mechanism of TSHR in hyperthyroid-associated osteoporosis. First, we observed that TSHR was downregulated in bone marrow mesenchymal stem cells (BMSCs) isolated from rats after culture in osteogenic medium for 7 days. Functionally, overexpression of TSHR accelerates BMSC osteogenic differentiation. Mechanistically, we predicted four potential miRNAs for TSHR. MiR-577 was validated to bind with TSHR. Rescue assays showed that miR-577 overexpression inhibited BMSC osteogenic differentiation via targeting TSHR. In vivo experiments showed that miR-577 aggravated bone loss and bone remodeling and our data showed that it is achieved by targeting TSHR in hyperthyroid-associated osteoporosis. This finding may deep our understanding of the pathogenesis of hyperthyroid-associated osteoporosis.

miR-146a-5p Promotes Chondrocyte Apoptosis and Inhibits Autophagy of Osteoarthritis by Targeting NUMB

OBJECTIVE

miR-146a-5p was found to be significantly upregulated in cartilage tissue of patients with osteoarthritis (OA). NUMB was shown to be involved in the autophagy regulation process of cells. We aimed to learn whether NUMB was involved in the apoptosis or autophagy process of chondrocytes in OA and related with miR-146a-5p.

METHODS

QRT-PCR was used to detect miR-146a-5p level in 22 OA cartilage tissues and 22 controls. The targets of miR-146a-5p were analyzed using software and the luciferase reporter experiment. The apoptosis and autophagy, and related proteins were detected in chondrocytes treated with miR-146a-5p mimic/inhibitor or pcDNA3.1-NUMB/si-NUMB and IL-1β, respectively. In vivo experiment, intra-articular injection of miR-146a-5p antagomir/NC was administered at the knee of OA male mice before and after model construction. Chondrocyte apoptosis and the expression of apoptosis and autophagy-related proteins were also detected.

RESULTS

miR-146a-5p was highly expressed in knee cartilage tissue of patients with OA, while NUMB was lowly expressed and negatively regulated by miR-146a-5p. Upregulation of miR-146a-5p can promote cell apoptosis and reduce autophagy of human and mouse chondrocytes by modulating the levels of cleaved caspase-3, cleaved PARP, Bax, Beclin 1, ATG5, p62, LC3-I, and LC3-II. Increasing the low level of NUMB reversed the effects of miR-146a-5p on chondrocyte apoptosis and autophagy. Intra-articular injection of miR-146a-5p antagomir can also reverse the effects of miR-146a-5p on the apoptosis and autophagy of knee joint chondrocytes in OA mice.

CONCLUSION

Downregulation of miR-146a-5p suppresses the apoptosis and promotes autophagy of chondrocytes by targeting NUMB in vivo and in vitro.

MicroRNA-146a-3p/HDAC1/KLF5/IKBα signal axis modulates plaque formation of atherosclerosis mice

BACKGROUND

Atherosclerosis (AS) is a multifocal, smoldering immune inflammatory disease of medium and large arteries driven by lipids. The aim of this study is to discuss the mechanism of microRNA-146a-3p (miR-146a-3p)/histone deacetylase 1 (HDAC1)/Krüppel-like factor 5 (KLF5)/inhibitors of kappa B α (IKBα) signal axis in plaque formation of AS mice.

METHODS

ApoE-/- mice were fed with high-fat feed for 12 weeks to establish AS mice model. The expression of miR-146a-3p, KLF5, HDAC1 and IKBα in aortic wall tissues of AS mice was tested. The targeting relationship between miR-146a-3p and HDAC1 was verified. AS mice were injected with miR-146a-3p antagomir or HDAC1 overexpression to verify the impacts of miR-146a-3p and HDAC1 on blood lipids and inflammatory factors in serum, aortic wall apoptotic cells, antioxidant stress capacity and the plaque area in AS mice. VECs proliferation and apoptosis were also measured in vitro.

RESULTS

miR-146a-3p and KLF5 were increased while HDAC1 and IKBα were reduced in aortic wall tissues of AS mice. miR-146a-3p directly targeted to HDAC1. Depletion of miR-146a-3p or restoration of HDAC1 was correlated to lower plasma lipid level, reduced inflammatory factors in serum, attenuated aortic wall apoptosis, increased antioxidant stress capacity and improved the stability of pathological plaque of AS mice. miR-146a-3p down-regulation or HDAC1 up-regulation promoted VECs proliferation and inhibited apoptosis.

CONCLUSION

Functional studies show that depleted miR-146a-3p advances HDAC1 and IKBα expression as well as inhibits KLF5 expression to facilitate the stability of pathological plaques in AS mice.

MKRN1 Ubiquitylates p21 to Protect against Intermittent Hypoxia-Induced Myocardial Apoptosis

Although chronic intermittent hypoxia- (IH-) induced myocardial apoptosis is an established pathophysiological process resulting in a poor prognosis for patients with obstructive sleep apnea syndrome, its underlying mechanism remains unclear. This study is aimed at exploring the role of makorin ring finger protein 1 (MKRN1) in IH-induced myocardial apoptosis and elucidating its molecular activity. First, the GSE2271 dataset was downloaded from the Gene Expression Omnibus database to identify the differentially expressed genes. Then, an SD rat model of IH, together with rat cardiomyocyte H9C2 and human cardiomyocyte AC16 IH models, was constructed. TUNEL, Western blot, and immunohistochemistry assays were used to detect cell apoptosis. Dihydroethidium staining was conducted to analyze the concentration of reactive oxygen species. In addition, RT-qPCR, Western blot, and immunohistochemistry were performed to measure the expression levels of MKRN1 and p21. The direct interaction between MKRN1 and p21 was determined using coimmunoprecipitation and ubiquitination analysis. MKRN1 expression was found to be downregulated in IH rat myocardial tissues as well as in H9C2 and AC16 cells. Upregulated expression of MKRN1 in H9C2 and AC16 cells alleviated the IH-induced reactive oxygen species production and cell apoptosis. Mechanistically, MKRN1 promoted p21 protein ubiquitination and the proteasome pathway degradation to negatively regulate p21 expression. Thus, MKRN1 regulates p21 ubiquitination to prevent IH-induced myocardial apoptosis.

Extracellular vesicle microRNA cargoes from intermittent hypoxia-exposed cardiomyocytes and their effect on endothelium

Intermittent hypoxia (IH), a main characteristic of obstructive sleep apnea (OSA) syndrome, is an independent risk factor of cardiovascular complications. However, the mechanism has not been fully elucidated. Growing evidence has revealed alterations of extracellular vesicle (EV) contents, mostly miRNAs, playing a pathogenic role in cardiovascular complications. In current study, we attempt to compare the disparity of myocardial EV miRNA components after IH or normoxia treatment and determine whether EVs from IH-treated cardiomyocytes could affect endothelial function. 63 differentially expressed miRNAs were identified in EVs from IH-exposed cardiomyocytes by miRNA chip assay. Among them, 16 miRNAs with homologous sequence in mouse and human were verified by qPCR assay and 11 miRNAs were proved with the same tendency as miRNA chip assay. KEGG predicted that the function of differentially expressed miRNA was enriched to Akt signaling pathway. Notably, EVs from IH-exposed cardiomyocytes dramatically impaired endothelial-dependent relaxation and inhibited Akt/eNOS expression in endothelial cells. This study provides the first evidence that IH significantly alters myocardial EV miRNA composition and reveals a novel role of myocardial EVs in endothelial function under IH status, which will help to understand the OSA- or IH-related endothelial dysfunction from a new scope.

An Update on Obstructive Sleep Apnea for Atherosclerosis: Mechanism, Diagnosis, and Treatment

The occurrence and development of atherosclerosis could be influenced by intermittent hypoxia. Obstructive sleep apnea (OSA), characterized by intermittent hypoxia, is world-wide prevalence with increasing morbidity and mortality rates. Researches remain focused on the study of its mechanism and improvement of diagnosis and treatment. However, the underlying mechanism is complex, and the best practice for OSA diagnosis and treatment considering atherosclerosis and related cardiovascular diseases is still debatable. In this review, we provided an update on research in OSA in the last 5 years with regard to atherosclerosis. The processes of inflammation, oxidative stress, autonomic nervous system activation, vascular dysfunction, platelet activation, metabolite dysfunction, small molecule RNA regulation, and the cardioprotective occurrence was discussed. Additionally, improved diagnosis such as, the utilized of portable device, and treatment especially with inconsistent results in continuous positive airway pressure and mandibular advancement devices were illustrated in detail. Therefore, further fundamental and clinical research should be carried out for a better understanding the deep interaction between OSA and atherosclerosis, as well as the suggestion of newer diagnostic and treatment options.

miR-3574 ameliorates intermittent hypoxia-induced cardiomyocyte injury through inhibiting Axin1

Objective: miRNAs play critical roles in the regulation of many cardiovascular diseases. However, its role and potential mechanism in cardiac injury caused by obstructive sleep apnea (OSA) remain poorly elucidated. In the present study, we aimed to investigate the effects of miR-3574 on cardiomyocyte injury under intermittent hypoxia (IH).

Results: We confirmed that IH inhibited cell viability, induced cell apoptosis and suppressed miR-3574 expression in the H9c2. miR-3574 overexpression could ameliorate the effects of IH on the cell viability and cell apoptosis in the H9c2. Axin1 was a target gene of miR-3574, and miR-3574 overexpression reduced the expression of Axin1. miR-3574 could inhibit the IH-induced cardiomyocyte injury via downregulating Axin1. However, Axin1 could partially reverse these effects of miR-3574.

Conclusion: Our study first reveals that miR-3574 could alleviate IH-induced cardiomyocyte injury by targeting Axin1, which may function as a novel and promising therapy target for OSA-associated cardiovascular diseases.

Methods: H9c2 were exposed to IH condition. CCK-8 assay was applied to determine cell viability of H9c2. qRT-PCR was conducted to measure the expression level of mRNA and miRNA. Western blot assay was then performed to detect the protein levels. Finally, we used dual-luciferase reporter assay identify the potential target of miR-3574.

Globular adiponectin alleviates chronic intermittent hypoxia-induced H9C2 cardiomyocytes apoptosis via ER-phagy induction

This study evaluated the effects of endoplasmic reticulum autophagy (ER-phagy) and globular adiponectin (gAPN) on chronic intermittent hypoxia (CIH)-induced H9C2 cardiomyocytes injury while investigating potential mechanisms of action. The CIH model of H9C2 cardiomyocytes was established in this study. CCK-8 assay was used to determine cell viability post-exposure to various CIH times and gAPN concentrations. Flow cytometry was used to observe H9C2 cardiomyocytes apoptosis and immunofluorescence was used to measure ER-phagy and SEC62 activation. Western blot was used to observe ER stress and AMPK pathway. Results indicated that ER stress was activated in H9C2 cardiomyocytes exposed to CIH. Inhibition of ER stress reduced CIH-induced cell apoptosis. gAPN attenuated CIH-induced ER stress and H9C2 cardiomyocytes apoptosis. ER-phagy and SEC62 protein level were induced by CIH, while gAPN highly enhanced these changes. Inhibition of SEC62 expression reduced ER-phagy and increased ER stress and H9C2 cardiomyocytes apoptosis. Moreover, gAPN induced AMPK expression. Inhibition of AMPK expression reduced SEC62-mediated ER-phagy and increased the H9C2 cardiomyocytes apoptosis. Altogether, our study suggested that gAPN upregulated SEC62-mediated ER-phagy to extenuate ER stress, and mitigated H9C2 cardiomyocytes apoptosis induced by CIH through AMPK activation.

Pathophysiological implications of hypoxia in human diseases

Oxygen is essentially required by most eukaryotic organisms as a scavenger to remove harmful electron and hydrogen ions or as a critical substrate to ensure the proper execution of enzymatic reactions. All nucleated cells can sense oxygen concentration and respond to reduced oxygen availability (hypoxia). When oxygen delivery is disrupted or reduced, the organisms will develop numerous adaptive mechanisms to facilitate cells survived in the hypoxic condition. Normally, such hypoxic response will cease when oxygen level is restored. However, the situation becomes complicated if hypoxic stress persists (chronic hypoxia) or cyclic normoxia-hypoxia phenomenon occurs (intermittent hypoxia). A series of chain reaction-like gene expression cascade, termed hypoxia-mediated gene regulatory network, will be initiated under such prolonged or intermittent hypoxic conditions and subsequently leads to alteration of cellular function and/or behaviors. As a result, irreversible processes occur that may cause physiological disorder or even pathological consequences. A growing body of evidence implicates that hypoxia plays critical roles in the pathogenesis of major causes of mortality including cancer, myocardial ischemia, metabolic diseases, and chronic heart and kidney diseases, and in reproductive diseases such as preeclampsia and endometriosis. This review article will summarize current understandings regarding the molecular mechanism of hypoxia in these common and important diseases.

LncRNA CYTOR attenuates sepsis-induced myocardial injury via regulating miR-24/XIAP

This work aims to investigate the function and mechanism of long non-coding RNA (lncRNA) cytoskeleton regulator RNA (CYTOR) in myocardial injury induced by sepsis. The sepsis-induced myocardial injury model in mice was established by intraperitoneal injection of LPS (10 mg/kg) in vivo, and cardiomyocyte H9c2 was treated with LPS to mimic sepsis in vitro. CYTOR expression and miR-24 expression were detected by qRT-PCR. After up-regulation or down-regulation of CYTOR and miR-24 expression in the H9c2 cells, and the viability of the cells was detected via MTT assay, and cell apoptosis was detected by TUNEL assay. Western blot was applied to determine the expression level of caspase 3, Bax and X-chromosome-linked inhibitor of apoptosis (XIAP). Interaction between CYTOR and miR-24 was determined by bioinformatics analysis, RT-PCR and dual luciferase reporter assay. Interaction between miR-24 and XIAP was determined through bioinformatics analysis, RT-PCR, western blot and dual luciferase reporter assay. CYTOR was markedly down-regulated. CYTOR interacted with miR-24, and negatively regulated its expression level. Over-expression of CYTOR or transfection of miR-24 inhibitors significantly promoted viability and inhibited apoptosis of H9c2 cells, while the knockdown of CYTOR and transfection of miR-24 mimics had opposite effects. CYTOR suppressed the expression level of apoptosis-related proteins, but miR-24 increased them. miR-24 directly targeted the 3'UTR of XIAP, and suppressed it, and XIAP was modulated indirectly by CYTOR. Down-regulation of CYTOR aggravates sepsis-induced cardiac injury via regulating miR-24 and XIAP.