LncRNA H19 targets miR-22 to modulate H2 O2 -induced deregulation in nucleus pulposus cell senescence, proliferation, and ECM synthesis through Wnt signaling

POSTN promotes nucleus pulposus cell senescence and extracellular matrix metabolism via activing Wnt/β-catenin and NF-κB signal pathway in intervertebral disc degeneration

BACKGROUND

Intervertebral disc (IVD) degeneration (IVDD) is a prevalent condition contributing to back pain and disability. Periostin (POSTN) has emerged as a potential molecular marker and therapeutic target in IVDD, prompting further investigation into its role and mechanisms.

METHODS

This study employs bioinformatics analysis combined with experimental validation to explore the role of POSTN in IVDD. Gene expression datasets from the GEO database were analyzed to identify genes associated with IVDD, and the effects of POSTN on rat nucleus pulposus (NP) cells senescence and extracellular matrix (ECM) metabolism were assessed both in vitro and in vivo.

RESULTS

Elevated POSTN expression was observed in degenerated discs from IVDD patients, correlating with disease severity. In vitro experiments demonstrated that POSTN promotes NP cells senescence and ECM metabolism in a dose- and time-dependent manner. In vivo studies confirmed that POSTN inhibition can ameliorate the progression of IVDD. Further mechanistic insights revealed that POSTN may exert its effects by activating the NF-κB and Wnt/β-catenin signaling pathways.

CONCLUSION

POSTN plays a significant role in the pathogenesis of IVDD, with its upregulated expression closely linked to NP cells senescence and ECM metabolism. Targeting POSTN could offer a novel therapeutic strategy for IVDD. Additionally, the study predicts small molecules that may inhibit POSTN expression, providing potential candidates for the development of new drug treatments.

Identification and validation of ferroptosis-related lncRNA signature in intervertebral disc degeneration

Low back pain influences people of every age and is one of the major contributors to the global cost of illness. Intervertebral disc degeneration (IVDD) is a major contributor to low back pain, but its pathogenesis is unknown. Recently, ferroptosis has been shown to have a substantial role in modulating IVDD progression. However, the function of ferroptosis-related long non-coding RNAs (lncRNAs) has rarely been reported in IVDD. Consequently, the research was conducted to explore the ferroptosis-related lncRNA signature in the IVDD occurrence and development. We analyzed two datasets (GSE167199 and GSE167931) archived in the NCBI Gene Expression Omnibus (GEO) public database. We screened differentially expressed genes (DEGs) and differentially expressed lncRNAs (DELncs) in these datasets using the limma package. Ferroptosis-related genes (FRGs) were derived from the FerrDb V2 website and the intersection of DEGs and FRGs was considered as differentially expressed ferroptosis-related genes (DFGs). These genes were then subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. Correlations between DFGs and DELncs were shown by Pearson test to determine differential expression of ferroptosis-related lncRNAs. The Pearson test showed that CPEB1-HTR2A-AS1 and ACSL3-DNAJC27-AS1 pairs had correlation coefficients over 0.9. Twenty ferroptosis-related lncRNAs were identified and validated in IVDD. Eight of these lncRNAs were upregulated in IVDD nucleus pulposus cells, including HTR2A-AS1, MIF-AS1, SLC8A1-AS1, LINC00942, DUXAP8, LINC00161, LUCAT1 and LINC01615. Twelve were downregulated in IVDD nucleus pulposus cells, including DNAJC27-AS1, H19, LINC01588, LINC02015, FLNC1, CARMN, PRKG1-AS1, APCDD1L-DT, LINC00839, LINC00536, LINC00710 and LINC01535. Eighteen of the 20 lncRNAs (excluding H19 and LUCAT1) were identified as ferroptosis-related lncRNAs for the first time and verified in IVDD. We have identified a ferroptosis-related lncRNA signature involved in IVDD and revealed a close relationship between CPEB1 and HTR2A-AS1, and between ACSL3 and DNAJC27-AS1. Our findings indicate that ferroptosis-related lncRNAs are a new target set for the early detection and therapy of IVDD.

Identification of key eRNAs for intervertebral disc degeneration by integrated multinomial bioinformatics analysis

BACKGROUND

Intervertebral disc degeneration (IVDD) is a common degenerative condition leading to abnormal stress distribution under load, causing intervertebral stenosis, facet joint degeneration, and foraminal stenosis. Very little is known about the molecular mechanism of eRNAs in IVDD.

METHODS

Gene expression profiles of 38 annulus disc samples composed of 27 less degenerated discs (LDs) and 11 more degenerated discs (MDs) were retrieved from the GEO database. Then, differentially expressed enhancer RNAs (DEeRNAs), differentially expressed target genes (DETGs), and differentially expressed transcription factors (DETFs), hallmark of cancer signalling pathways according to GSVA; the types and quantity of immune cells according to CIBERSORT; and immune gene sets according to ssGSEA were analysed to construct an IVDD-related eRNA network. Then, multidimensional validation was performed to explore the interactions among DEeRNAs, DETFs and DEGs in space.

RESULTS

A total of 53 components, 14 DETGs, 15 DEeRNAs, 3 DETFs, 5 immune cells, 9 hallmarks, and 7 immune gene sets, were selected to construct the regulatory network. After validation by online multidimensional databases, 21 interactive DEeRNA-DEG-DETF axes related to IVDD exacerbation were identified, among which the C1S-CTNNB1-CHD4 axis was the most significant.

CONCLUSION

Based upon the results of our study, we theorize that the C1S-CTNNB1-CHD4 axis plays a vital role in IVDD exacerbation. Specifically, C1S recruits CTNNB1 and upregulates the expression of CHD4 in IVDD, and subsequently, CHD4 suppresses glycolysis and activates oxidative phosphorylation, thus generating insoluble collagen fibre deposits and leading to the progression of IVDD. Overall, these DEeRNAs could comprise promising therapeutic targets for IVDD due to their high tissue specificity.

MicroRNA-targeting nanomedicines for the treatment of intervertebral disc degeneration

Low back pain stands as a pervasive global health concern, afflicting almost 80% of adults at some point in their lives with nearly 40% attributable to intervertebral disc degeneration (IVDD). As only symptomatic relief can be offered to patients there is a dire need for innovative treatments.Given the accumulating evidence that multiple microRNAs (miRs) are dysregulated during IVDD, they could have a huge potential against this debilitating condition. The way miRs can profoundly modulate signaling pathways and influence several cellular processes at once is particularly exciting to tackle this multifaceted disorder. However, miR delivery encounters extracellular and intracellular biological barriers. A promising technology to address this challenge is the vectorization of miRs within nanoparticles, providing both protection and enhancing their uptake within the scarce target cells of the degenerated IVD. This comprehensive review presents the diverse spectrum of miRs' connection with IVDD and demonstrates their therapeutic potential when vectorized in nanomedicines.

Mesoporous bioactive glass scaffolds for the delivery of bone marrow stem cell-derived osteoinductive extracellular vesicles lncRNA promote senescent bone defect repair by targeting the miR-1843a-5p/Mob3a/YAP axis

Bone repair in elderly patients poses a huge challenge due to the age-related progressive decline in regenerative abilities attributed to the senescence of bone marrow stem cells (BMSCs). Bioactive scaffolds have been applied in bone regeneration due to their various biological functions. In this study, we aimed to fabricate functionalized bioactive scaffolds through loading osteoinductive extracellular vesicles (OI-EVs) based on mesoporous bioactive glass (MBG) scaffolds (1010 particles/scaffold) and to investigate its effects on osteogenesis and senescence of BMSCs. The results suggested that OI-EVs upregulate the proliferative and osteogenic capacities of senescent BMSCs. More importantly, The results showed that loading OI-EVs into MBG scaffolds achieved better bone regeneration. Furthermore, OI-EVs and BMSCs RNAs bioinformatics analysis indicated that OI-EVs play roles through transporting pivotal lncRNA acting as a "sponge" to compete with Mob3a for miR-1843a-5p to promote YAP dephosphorylation and nuclear translocation, ultimately resulting in elevated proliferation and osteogenic differentiation and reduced senescence-related phenotypes. Collectively, these results suggested that the OI-EVs lncRNA ceRNA regulatory networks might be the key point for senescent osteogenesis. More importantly, the study indicated the feasibility of loading OI-EVs into scaffolds and provided novel insights into biomaterial design for facilitating bone regeneration in the treatment of senescent bone defects. STATEMENT OF SIGNIFICANCE: Constructing OI-EVs/MBG delivering system and verification of its bone regeneration enhancement in senescent defect repair. Aging bone repair poses a huge challenge due to the age-related progressive degenerative decline in regenerative abilities attributed to the senescence of BMSCs. OI-EVs/MBG delivering system were expected as promising treatment for senescent bone repair, which could provide an effective strategy for bone regeneration in elderly patients. Clarification of potential OI-EVs lncRNA ceRNA regulatory mechanism in senescent bone regeneration OI-EVs play important roles through transferring lncRNA-ENSRNOG00000056625 sponging miR-1843a-5p that targeted Mob3a to activate YAP translocation into nucleus, ultimately alleviate senescence, promote proliferation and osteogenic differentiation in O-BMSCs, which provides theoretical basis for EVs-mediated therapy in future clinical works.

Unraveling the mechanisms of intervertebral disc degeneration: an exploration of the p38 MAPK signaling pathway

Intervertebral disc (IVD) degeneration (IDD) is a worldwide spinal degenerative disease. Low back pain (LBP) is frequently caused by a variety of conditions brought on by IDD, including IVD herniation and spinal stenosis, etc. These conditions bring substantial physical and psychological pressure and economic burden to patients. IDD is closely tied with the structural or functional changes of the IVD tissue and can be caused by various complex factors like senescence, genetics, and trauma. The IVD dysfunction and structural changes can result from extracellular matrix (ECM) degradation, differentiation, inflammation, oxidative stress, mechanical stress, and senescence of IVD cells. At present, the treatment of IDD is basically to alleviate the symptoms, but not from the pathophysiological changes of IVD. Interestingly, the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway is involved in many processes of IDD, including inflammation, ECM degradation, apoptosis, senescence, proliferation, oxidative stress, and autophagy. These activities in degenerated IVD tissue are closely relevant to the development trend of IDD. Hence, the p38 MAPK signaling pathway may be a fitting curative target for IDD. In order to better understand the pathophysiological alterations of the intervertebral disc tissue during IDD and offer potential paths for targeted treatments for intervertebral disc degeneration, this article reviews the purpose of the p38 MAPK signaling pathway in IDD.

Activation of the Nrf-2 pathway by pinocembrin safeguards vertebral endplate chondrocytes against apoptosis and degeneration caused by oxidative stress

AIM

The occurrence and progression of intervertebral disc degeneration (IDD) are significantly influenced by the cartilaginous endplate (CEP). Pinocembrin (PIN), a type of flavonoid present in propolis and botanicals, demonstrates both antioxidant and anti-inflammatory characteristics, which could potentially be utilized in management. Therefore, it is crucial to investigate how PIN protects against CEP degeneration and its mechanisms, offering valuable insights for IDD therapy.

MATERIALS AND METHODS

To investigate the protective impact of PIN in vivo, we created the IDD mouse model through bilateral facet joint transection. In vitro, an IDD pathological environment was mimicked by applying TBHP to treat endplate chondrocytes.

KEY FINDINGS

In vivo, compared with the IDD group, the mouse in the PIN group effectively mitigates IDD progression and CEP calcification. In vitro, the activation of the Nrf-2 pathway improves the process of Parkin-mediated autophagy in mitochondria and decreases ferroptosis in chondrocytes. This enhancement promotes cell survival by addressing the imbalance of redox during pathological conditions related to IDD. Knocking down Nrf-2 with siRNA fails to provide protection to endplate chondrocytes against apoptosis and degeneration.

SIGNIFICANCE

The Nrf-2-mediated activation of mitochondrial autophagy and suppression of ferroptosis play a crucial role in safeguarding against oxidative stress-induced degeneration and calcification of CEP through the protective function of PIN. To sum up, this research offers detailed explanations about how PIN can protect against apoptosis and calcification in CEP, providing valuable information about the development of IDD and suggesting possible treatment approaches.

Cellular Senescence in Intervertebral Disc Aging and Degeneration: Molecular Mechanisms and Potential Therapeutic Opportunities

Closely associated with aging and age-related disorders, cellular senescence (CS) is the inability of cells to proliferate due to accumulated unrepaired cellular damage and irreversible cell cycle arrest. Senescent cells are characterized by their senescence-associated secretory phenotype that overproduces inflammatory and catabolic factors that hamper normal tissue homeostasis. Chronic accumulation of senescent cells is thought to be associated with intervertebral disc degeneration (IDD) in an aging population. This IDD is one of the largest age-dependent chronic disorders, often associated with neurological dysfunctions such as, low back pain, radiculopathy, and myelopathy. Senescent cells (SnCs) increase in number in the aged, degenerated discs, and have a causative role in driving age-related IDD. This review summarizes current evidence supporting the role of CS on onset and progression of age-related IDD. The discussion includes molecular pathways involved in CS such as p53-p21CIP1, p16INK4a, NF-κB, and MAPK, and the potential therapeutic value of targeting these pathways. We propose several mechanisms of CS in IDD including mechanical stress, oxidative stress, genotoxic stress, nutritional deprivation, and inflammatory stress. There are still large knowledge gaps in disc CS research, an understanding of which will provide opportunities to develop therapeutic interventions to treat age-related IDD.

Nucleus pulposus related lncRNA and mRNA expression profiles in intervertebral disc degeneration

In the present study, we aimed to have a comprehensive understanding of nucleus pulposus related long noncoding RNA (lncRNA) and mRNA expression profiles in intervertebral disc degeneration (IDD). In total, 2418 mRNAs and 528 lncRNAs were found to be differentially expressed in the IDD group compared with the Control group. Combining microarray datasets and sequencing data, 5 overlapping DEMs and 7 overlapping DELs were identified. NF-κB signaling pathway, PI3K-Akt signaling pathway and Wnt/β-catenin signaling pathway were strongly linked with enriched GO terms and KEGG pathways. The ceRNA network suggested that lnc-TMEM44-AS1-hsa-miR-206-HDAC4 may be one crucial axis in IDD. PPI network analysis was constructed with 309 nodes and 129 edges. And the highest connectivity degrees were ALB, APOB and CCL2. This study suggested that specific lncRNAs and ceRNA axes may be crucial in the development of IDD. It provides a new perspective for delaying IDD process and enhancing intervertebral disc repair.

Methionine Restriction Improves Cognitive Ability by Alleviating Hippocampal Neuronal Apoptosis through H19 in Middle-Aged Insulin-Resistant Mice

LncRNA H19 has been reported to regulate apoptosis and neurological diseases. Hippocampal neuron apoptosis damages cognitive ability. Methionine restriction (MR) can improve cognitive impairment. However, the effect of MR on hippocampal neuronal apoptosis induced by a high-fat diet (HFD) in middle-aged mice remains unclear. For 25 weeks, middle-aged mice (C57BL/6J) were given a control diet (CON, 0.86% methionine + 4.2% fat), a high-fat diet (HFD, 0.86% methionine + 24% fat), or an HFD + MR diet (HFMR, 0.17% methionine + 24% fat). The HT22 cells were used to establish the early apoptosis model induced by high glucose (HG). In vitro, the results showed that MR significantly improved cell viability, suppressed the generation of ROS, and rescued HT22 cell apoptosis in a gradient-dependent manner. In Vivo, MR inhibited the damage and apoptosis of hippocampal neurons caused by a high-fat diet, reduced hippocampal oxidative stress, improved hippocampal glucose metabolism, relieved insulin resistance, and enhanced cognitive ability. Furthermore, MR could inhibit the overexpression of H19 and caspase-3 induced by HFD, HG, or H2O2 in vivo and in vitro, and promoted let-7a, b, e expression. These results indicate that MR can protect neurons from HFD-, HG-, or H2O2-induced injury and apoptosis by inhibiting H19.

Morroniside attenuates nucleus pulposus cell senescence to alleviate intervertebral disc degeneration via inhibiting ROS-Hippo-p53 pathway

Intervertebral disc (IVD) degeneration (IVDD) which is highly prevalent within the elderly population, is a leading cause of chronic low back pain and disability. Nucleus pulposus (NP) cell senescence plays an indispensable role in the pathogenesis of IVDD. Morroniside is a major iridoid glycoside and one of the quality control metrics of Cornus officinalis Siebold & Zucc (CO). An increasing body of evidence suggests that morroniside and CO-containing formulae share many similar biological effects, including anti-inflammatory, anti-oxidative, and anti-apoptotic properties. In a previous study, we reported that Liuwei Dihuang Decoction, a CO-containing formula, is effective for treating IVDD by targeting p53 expression; however, the therapeutic role of morroniside on IVDD remains obscure. In this study, we assessed the pharmacological effects of morroniside on NP cell senescence and IVDD pathogenesis using a lumbar spine instability surgery-induced mouse IVDD model and an in vitro H2O2-induced NP cell senescence model. Our results demonstrated that morroniside administration could significantly ameliorate mouse IVDD progression, concomitant with substantial improvement in extracellular matrix metabolism and histological grading score. Importantly, in vivo and in vitro experiments revealed that morroniside could significantly reduce the increase in SA-β-gal activities and the expression of p53 and p21, which are the most widely used indicators of senescence. Mechanistically, morroniside suppressed ROS-induced aberrant activation of Hippo signaling by inhibiting Mst1/2 and Lats1/2 phosphorylation and reversing Yap/Taz reduction, whereas blockade of Hippo signaling by Yap/Taz inhibitor-1 or Yap/Taz siRNAs could antagonize the anti-senescence effect of morroniside on H2O2-induced NP cell senescence model by increasing p53 expression and activity. Moreover, the inhibition of Hippo signaling in the IVD tissues by morroniside was further verified in mouse IVDD model. Taken together, our findings suggest that morroniside protects against NP cell senescence to alleviate IVDD progression by inhibiting the ROS-Hippo-p53 pathway, providing a potential novel therapeutic approach for IVDD.

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.

Treatment of Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) causes a variety of signs and symptoms, such as low back pain (LBP), intervertebral disc herniation, and spinal stenosis, which contribute to high social and economic costs. IDD results from many factors, including genetic factors, aging, mechanical injury, malnutrition, and so on. The pathological changes of IDD are mainly composed of the senescence and apoptosis of nucleus pulposus cells (NPCs), the progressive degeneration of extracellular matrix (ECM), the fibrosis of annulus fibrosus (AF), and the inflammatory response. At present, IDD can be treated by conservative treatment and surgical treatment based on patients' symptoms. However, all of these can only release the pain but cannot reverse IDD and reconstruct the mechanical function of the spine. The latest research is moving towards the field of biotherapy. Mesenchymal stem cells (MSCs) are regard as the potential therapy of IDD because of their ability to self-renew and differentiate into a variety of tissues. Moreover, the non-coding RNAs (ncRNAs) are found to regulate many vital processes in IDD. There have been many successes in the in vitro and animal studies of using biotherapy to treat IDD, but how to transform the experimental data to real therapy which can apply to humans is still a challenge. This article mainly reviews the treatment strategies and research progress of IDD and indicates that there are many problems that need to be solved if the new biotherapy is to be applied to clinical treatment of IDD. This will provide reference and guidance for clinical treatment and research direction of IDD.

CB2R Attenuates Intervertebral Disc Degeneration by Delaying Nucleus Pulposus Cell Senescence through AMPK/GSK3β Pathway

Nucleus pulposus (NP) cell (NPC) senescence is one of the main causes of intervertebral disc degeneration (IVDD). However, the underlying mechanism of NPC senescence is still unclear. The cannabinoid type 2 receptor (CB2R) is a member of the cannabinoid system and plays an important role in antioxidative stress, anti-inflammatory and antisenescence activities. In this study, we used a hydrogen peroxide (H₂O₂)-induced NPC senescence model and a rat acupuncture IVDD model to explore the role of CB2R in IVDD in vitro and in vivo. First, we confirmed that the expression of p16INK4a in the NP tissues of IVDD patients and rat acupuncture IVDD models obviously increased accompanied by a decrease in CB2R expression. Subsequently, we found that activation of CB2R significantly reduced the number of SA-β-gal positive cells and suppressed the expression of p16INK4a and senescence-related secretory phenotypes [SASP, including matrix metalloproteinase 9 and 13 (MMP9, MMP13) and high mobility group protein b1 (HMGB1)]. In addition, activation of CB2R promoted the expression of collagen type II (Col-2) and SRY-Box transcription factor 9 (SOX9), inhibit the expression of collagen type X (Col-X), and restore the balance of extracellular matrix (ECM) metabolism. In addition, the AMPK/GSK3β pathway was shown to play an important role in CB2R regulation of NPC senescence. Inhibition of AMPK expression reversed the effect of JWH015 (a CB2R agonist). Finally, we further demonstrated that in the rat IVDD model, the AMPK/GSK3β pathway was involved in the regulation of CB2R on NPC senescence. In conclusion, our experimental results prove that CB2R plays an important role in NPC senescence. Activation of CB2R can delay NPC senescence, restore the balance of ECM metabolism, and attenuate IVDD.

Long Non-Coding RNAs H19 and HOTAIR Implicated in Intervertebral Disc Degeneration

Objective: Intervertebral disc degeneration (IDD) is the major cause of low back pain. We aimed to identify the key genes for IDD pathogenesis.

Methods: An integrated analysis of microarray datasets of IDD archived in public Gene Expression Omnibus was performed. Bioinformatics analyses including identification of differentially expressed mRNAs/microRNAs/long non-coding RNAs (DEMs/DEMis/DELs), pathway enrichment, and competitive endogenous RNA (ceRNA) network construction were performed to give insights into the potential functions of differentially expressed genes (DEGs, including DEMs, DEMis, and DELs). The diagnostic value of DEMis in distinguishing IDD from normal controls was evaluated through receiver operating characteristic (ROC) analysis.

Results: DEGs were identified in IDD, including H19 and HOTAIR. In the DEMis–DEMs network of IDD, miR-1291, miR-4270, and miR-320b had high connectivity with targeted DEMs. Cell death biological processes and the JAK–STAT pathway were significantly enriched from targeted DEMs. The area under the curve (AUC) of 10 DEMs including miR-1273e, miR-623, miR-518b, and miR-1291 in ROC analysis was more than 0.8, which indicated that those 10 DEMs had diagnostic value in distinguishing IDD from normal individuals.

Conclusions: DELs H19 and HOTAIR were related to IDD pathogenesis. Cell death biological processes and the JAK–STAT pathway might play key roles in IDD development.

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

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

SKI knockdown suppresses apoptosis and extracellular matrix degradation of nucleus pulposus cells via inhibition of the Wnt/β-catenin pathway and ameliorates disc degeneration

This study aimed to determine the effects of SKI on interleukin (IL)-1β-induced apoptosis of nucleus pulposus (NP) cells, intervertebral disc degeneration (IDD), and the Wnt signaling pathway. NP tissue specimens of different Pfirrmann grades (II-V) were collected from patients with different grades of IDD. Real-time polymerase chain reaction and western blotting were used to compare SKI mRNA and protein expression in NP tissues from patients. Using the IL-1β-induced IDD model, NP cells were infected with lentivirus-coated si-SKI to downregulate the expression of SKI and treated with LiCl to evaluate the involvement of the Wnt/β-catenin signaling pathway. Western blotting, immunofluorescence, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were used to detect NP cell apoptosis, extracellular matrix (ECM) metabolism, and related protein expression changes in the Wnt/β-catenin signaling pathway. To investigate the role of SKI in vivo, a rat IDD model was established by needle puncture of the intervertebral disc. Rats were injected with lentivirus-coated si-SKI and evaluated by magnetic resonance imaging (MRI), and hematoxylin and eosin (HE) and safranin O staining. SKI expression positively correlated with the severity of human IDD. In the IL-1β-induced NP cell degeneration model, SKI expression increased significantly and reached a peak at 24 h. SKI knockdown protected against IL-1β-induced NP cell apoptosis and ECM degradation. LiCl treatment reversed the protective effects of si-SKI on NP cells. Furthermore, lentivirus-coated si-SKI injection partially reversed the NP tissue damage in the IDD model in vivo. SKI knockdown reduced NP cell apoptosis and ECM degradation by inhibiting the Wnt/β-catenin signaling pathway, ultimately protecting against IDD. Therefore, SKI may be an effective target for IDD treatment.

Bioinformatics-Based Research on Key Genes and Pathways of Intervertebral Disc Degeneration

OBJECTIVE

To find out the pathways and key genes and to reveal disc degeneration pathogenesis based on bioinformatic analyses.

DESIGN

The GSE70362 dataset was downloaded from the GEO (Gene Expression Omnibus) database. Differentially expressed genes (DEGs) between the patients having disc degeneration and healthy controls were screened by Limma package in R language. Critical genes were identified by adopting gene ontologies (GOs), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and protein-protein interaction (PPI) networks.

RESULTS

We identified 112 DEGs, including 60 genes which were upregulated and 52 that were downregulated. Analyses, such as GO and KEGG demonstrated that the DEGs got enriched in 4 biological processes and 2 signaling pathways, mainly related to disc degeneration. The PPI network analyses identified 5 key proteins, CCND1 (cyclin D1), GATA3, TNFSF11, LEF1, and DKK1 (Dickkopf related protein 1).

CONCLUSION

In this study, the DEGs and pathways determined promoted us understand the disc degeneration mechanisms. Also, the study may contribute novel biomarkers for the diagnosis and prevention of disc degeneration, and seek new treatment methods to repair and even regenerate degenerative intervertebral disc.

The Functions of LncRNA H19 in the Heart

Cardiovascular diseases (CVDs) are major causes of morbidity and mortality worldwide. Great effort has been put into exploring early diagnostic biomarkers and innovative therapeutic strategies for preventing CVD progression over the last two decades. Long non-coding RNAs (lncRNAs) have been identified as novel regulators in cardiac development and cardiac pathogenesis. For example, lncRNA H19 (H19), also known as a fetal gene abundant in adult heart and skeletal muscles and evolutionarily conserved in humans and mice, has a regulatory role in aortic aneurysm, myocardial hypertrophy, extracellular matrix reconstitution, and coronary artery diseases. Yet, the exact function of H19 in the heart remains unknown. This review summarises the functions of H19 in the heart and discusses the challenges and possible strategies of H19 research for cardiovascular disease.

Interactions Among lncRNA/circRNA, miRNA, and mRNA in Musculoskeletal Degenerative Diseases

Musculoskeletal degenerative diseases (MSDDs) are pathological conditions that affect muscle, bone, cartilage, joint and connective tissue, leading to physical and functional impairments in patients, mainly consist of osteoarthritis (OA), intervertebral disc degeneration (IDD), rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) are novel regulators of gene expression that play an important role in biological regulation, involving in chondrocyte proliferation and apoptosis, extracellular matrix degradation and peripheral blood mononuclear cell inflammation. Research on MSDD pathogenesis, especially on RA and AS, is still in its infancy and major knowledge gaps remain to be filled. The effects of lncRNA/circRNA-miRNA-mRNA axis on MSDD progression help us to fully understand their contribution to the dynamic cellular processes, provide the potential OA, IDD, RA and AS therapeutic strategies. Further studies are needed to explore the mutual regulatory mechanisms between lncRNA/circRNA regulation and effective therapeutic interventions in the pathology of MSDD.

MAPK /ERK signaling pathway: A potential target for the treatment of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a chronic skeletal muscle degenerative disease, which is considered the main cause of low back pain. It seriously affects the quality of life of patients and consequently brings a heavy economic burden to their families and the society. Although IDD is considered a natural process in degenerative lesions, it is mainly caused by aging, trauma, genetic susceptibility and other factors. It is closely related to changes in the tissue structure and function, including the progressive destruction of extracellular matrix, cell aging, cell death of the intervertebral disc (IVD), inflammation, and impairment of tissue biomechanical function. Currently, the treatment of IDD is aimed at alleviating symptoms rather than at targeting pathological changes in the IVD. Furthermore, the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway is closely related to various pathological processes in IDD, and the activation of the MAPK/ERK pathway promotes the degradation of the IVD extracellular matrix, cell aging, apoptosis, and inflammatory responses. It also induces autophagy and oxidative stress that accelerate the IVD process. In our current review, we summarize the latest developments in the negative regulation of IDD after activation of the MAPK/ERK signaling pathway and emphasize on its influence on IDD. Targeting this pathway may become an attractive treatment strategy for IDD in the near future.

SIRT3 mitigates intervertebral disc degeneration by delaying oxidative stress-induced senescence of nucleus pulposus cells

Senescence of nucleus pulposus (NP) cells (NPC) is a major cause of intervertebral disc degeneration (IVDD), so delay NPC senescence may be beneficial for mitigating IVDD. We studied the effect and mechanism of silent information regulator 2 homolog 3 (SIRT3) on NPC senescence in vivo and in vitro. First, we observed SIRT3 expression in normal and degenerated NPC with immunohistochemical and immunofluorescence staining. Second, using SIRT3 lentivirus transfection, reactive oxygen species probe, senescence-associated β-galactosidase staining, polymerase chain reaction, and western blot to observe the oxidative stress, senescence, and degeneration degree among groups. Subsequently, pretreatment with adenosine monophosphate-activated protein kinase (AMPK) agonists and inhibitors, observing oxidative stress, senescence, and degeneration degree among groups. Finally, the IVDD model was constructed and divided into Ctrl, Vehicle, LV-shSIRT3, and LV-SIRT3 groups. X-ray and magnetic resonance imaging scans were performed on rat's tails after 1 week; hematoxylin and eosin and safranin-O staining were used to evaluate the degree of IVDD; immunofluorescence staining was used to observe SIRT3 expression; immunohistochemical staining was used to observe oxidative stress, senescence, and degeneration degree of NP. We found that SIRT3 expression is reduced in degenerated NP tissues but increased in H2 O2 -induced NPC. Moreover, SIRT3 upregulation decreased oxidative stress, delayed senescence, and degeneration of NPC. In addition, activation of the AMPK/PGC-1α pathway can partially mitigate the NPC oxidative stress, senescence, and degeneration caused by SIRT3 knockdown. The study in vivo revealed that local SIRT3 overexpression can significantly reduce oxidative stress and ECM degradation of NPC, delay NPC senescence, thereby mitigating IVDD. In summary, SIRT3 mediated by the AMPK/PGC-1α pathway mitigates IVDD by delaying oxidative stress-induced NPC senescence.

LncRNA H19 Aggravates Intervertebral Disc Degeneration by Promoting the Autophagy and Apoptosis of Nucleus Pulposus Cells Through the miR-139/CXCR4/NF-κB Axis

The etiology of lumbocrural pain is closely related to intervertebral disc degeneration (IDD). Long noncoding RNAs (lncRNAs) serve crucial roles in IDD progression. This study investigated the effect of lncRNA H19 on autophagy and apoptosis of nucleus pulposus cells (NPCs) in IDD. The rat model of IDD was established. Normal NPCs and degenerative NPCs (DNPCs) were cultured in vitro. H19 expression in IDD rat was detected. DNPCs were treated with si-H19 to evaluate autophagy and apoptosis of DNPCs. The binding relationships between H19 and miR-139-3p, and miR-139-3p and CXCR4 were verified. DNPCs were co-transfected si-H19 and miR-139-3p inhibitor. The phosphorylation of NF-κB pathway-related p65 in DNPCs was detected. LncRNA H19 was upregulated in IDD rats. Downregulation of H19 inhibited autophagy and apoptosis of DNPCs. LncRNA H19 sponged miR-139-3p to inhibit CXCR4 expression. si-H19 and miR-139-3p inhibitor co-treatment induced autophagy and apoptosis, and enhanced CXCR4 expression. si-H19 decreased p-p65 phosphorylation, while si-H19 and miR-139-3p inhibitor co-treatment partially elevated p-p65 phosphorylation. In conclusion, lncRNA H19 facilitated the autophagy and apoptosis of DNPCs by the miR-139-3p/CXCR4/NF-κB axis, thereby aggravating IDD. This study may offer new insights for the management of IDD.

NFKB2 inhibits NRG1 transcription to affect nucleus pulposus cell degeneration and inflammation in intervertebral disc degeneration

Extracellular matrix degradation, reactive oxygen species (ROS) generation, and inflammation in nucleus pulposus (NP) cells contribute to the progression of intervertebral disc degeneration (IDD). NRGs (Neuregulins) play a vital role in the development of the nervous system. In the present study, we found that NRG1 was downregulated within degenerative intervertebral disc and NP tissues, according to both bioinformatics and experimental analyses. Within IL-1β-stimulated NP cells, we observed degenerative and inflammatory changes, including inhibited cell viability, promoted cell apoptosis and ROS accumulation, reduced collagen II and aggrecan proteins, elevated MMP-3/13 and ADAMTS-4/5 proteins, and upregulated IL-6 and TNF-α mRNA levels. Within IL-1β-stimulated NP cells, NRG1 expression was also downregulated. NRG1 overexpression attenuated, whereas NRG1 silencing aggravated IL-1β-induced degenerative and inflammatory changes. Moreover, NRG1 regulated ErbB2/3 activation, contributing to the NRG1 protective function in NP cells. NFKB2 directly targeted the promoter region of NRG1 and inhibited NRG1 expression. In IL-1β-stimulated NP cells, silencing NFKB2 attenuated, whereas silencing NRG1 aggravated the degenerative changes and inflammation; the effects of NFKB2 silencing were significantly reversed by NRG1 silencing. In conclusion, NRG1 expression is downregulated within degenerative NP tissue samples and IL-1β-stimulated NP cells. NRG1 might protect against IL-1β-induced degenerative changes and inflammation. The upregulated NFKB2 might be the reason of NRG1 downregulation in degenerative NP tissues.

The role of miRNA, lncRNA and circRNA in the development of intervertebral disk degeneration (Review)

Intervertebral disc degeneration (IVDD) is a degenerative musculoskeletal disorder with multiple causative factors, such as age, genetics, mechanics and life style. IVDD contributes to non-specific lower back pain (NLBP), which is a globally prevalent and debilitating musculoskeletal disorder. NLBP has a substantial impact on medical resources and creates an economic burden for the public. Dysregulated phenotypes of nucleus pulposus (NP) cells and endplate chondrocytes, such as proliferation, senescence and apoptosis, along with aberrant expression of extracellular matrix components, including type II collagen and aggrecan, are involved in the pathological process of IVDD. Evidence indicates that non-coding RNAs, mainly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), play a vital role in the development of IVDD. In the present review, the potential molecular mechanisms of miRNAs, lncRNAs and circRNAs in the initiation and progression of IVDD were described based on the latest literature. Furthermore, ways to influence the functions of NP cells and endplate chondrocytes in IVDD were also summarized. The presented insights suggested that non-coding RNAs may function as potential targets for the treatment of IVDD.

MicroRNA-27b inhibits the development of melanoma by targeting MYC

Cutaneous malignant melanoma is a malignancy with one of the fastest increasing incidence rates worldwide; however, the mechanism underlying the occurrence and development of melanoma remains unclear. The aim of the present study was to identify novel biomarkers for the occurrence and development of melanoma. The results of the present study demonstrated that the expression levels of microRNA (miR)-27b were decreased in melanoma tissue samples compared with those in adjacent noncancerous tissue samples and cells according to online and experimental data. By contrast, MYC expression levels were upregulated in melanoma compared with those in adjacent noncancerous tissue samples. miR-27b overexpression significantly inhibited A375 and A2085 melanoma cell DNA synthesis, viability and invasive ability. Dual-luciferase reporter assay results demonstrated that miR-27b inhibited MYC expression through binding to the 3′-untranslated region of MYC mRNA. MYC knockdown in melanoma cells exerted similar effects to those of miR-27b overexpression on DNA synthesis, cell viability and invasive ability; the effects of miR-27b inhibition were significantly reversed by MYC knockdown. In conclusion, the miR-27b/MYC axis may modulate malignant melanoma cell biological behaviors and may be a potential target for melanoma treatment.

Role of the Wnt pathway in the formation, development, and degeneration of intervertebral discs

Intervertebral disc degeneration (IVDD) is an age-related degenerative disease that is the main cause of low back pain. It seriously affects the quality of life of patients and places a heavy economic burden on families and society. The Wnt pathway plays an important role in the growth, development, and degeneration of intervertebral discs (IVDs). In the embryonic stage, the Wnt pathway participates in the growth and development of IVD by promoting the transformation of progenitor cells into notochord cells and the extension of the notochord. However, the activation of the Wnt pathway after birth promotes IVD cell senescence, apoptosis, and degradation of the extracellular matrix and induces the production of inflammatory factors, thereby accelerating the IVDD process. This article reviews the relationship between the Wnt pathway and IVD, emphasizing its influence on IVD growth, development, and degeneration. Targeting this pathway may become an effective strategy for the treatment of IVDD.

The NLRP3 inflammasome: Multiple activation pathways and its role in primary cells during ventricular remodeling

Inflammasomes are a group of multiprotein signaling complexes located in the cytoplasm. Several inflammasomes have been identified, including NLRP1, NLRP2, NLRP3, AIM2, and NLRC4. Among them, NLRP3 was investigated in most detail, and it was reported that it can be activated by many different stimuli. Increased NLRP3 protein expression and inflammasome assembly lead to caspase-1 mediated maturation and release of IL-1β, which triggers inflammation and pyroptosis. The activation of the NLRP3 inflammasome has been widely reported in studies of tumors and neurological diseases, but relatively few studies on the cardiovascular system. Ventricular remodeling (VR) is an important factor contributing to heart failure (HF) after myocardial infarction (MI). Consequently, delaying VR is of great significance for improving heart function. Studies have shown that the NLRP3 inflammasome plays an essential role in the process of VR. Here, we reviewed the latest studies on the activation pathway of the NLRP3 inflammasome, focusing on the effects of the NLRP3 inflammasome in primary cells during VR, and finally discuss future research directions in this field.

The miR-623/CXCL12 axis inhibits LPS-induced nucleus pulposus cell apoptosis and senescence

Nucleus pulposus cell (NPC) is the major cell type maintaining the physiological function of intervertebral discs by producing extracellular matrix (ECM). NPC apoptosis and senescence together contribute to NPC loss, finally leading to intervertebral disc degeneration (IDD). Herein, miR-623 showed to be downregulated within IDD tissue samples according to both bioinformatics and experimental analyses. In LPS-injured NPCs, miR-623 overexpression promoted LPS-suppressed cell proliferation; moreover, miR-623 overexpression inhibited cell apoptosis and senescence, increased ECM secretion, and reduced levels of inflammatory factors. In contrast to miR-623, CXCL12 expression was significantly upregulated in IDD tissues; miR-623 directly bound CXCL12 to inhibit its expression. In LPS-stimulated NPCs, CXCL12 silencing also LPS-induced changes in cell proliferation, cell senescence, ECM secretion, and inflammatory factor levels. More importantly, CXCL12 overexpression aggravated LPS-induced changes and significantly reversed the protective effects of miR-623 overexpression. In conclusion, the miR-623/CXCL12 axis could affect NPC apoptosis and senescence, ECM deposition, and inflammatory factor levels under LPS stimulation in vitro. The p65 signaling might be involved.

Circ-CCS is identified as a cancer-promoting circRNA in lung cancer partly by regulating the miR-383/E2F7 axis

BACKGROUND

Increasing biomolecules have been found to be involved in the lung cancer development. This study will perform the function and mechanism analyses of a novel circular RNA copper chaperone for superoxide dismutase (circ-CCS) in lung cancer.

METHODS

Circ-CCS, microRNA-383 (miR-383) and E2F transcription factor 7 (E2F7) were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was detected using Cell Counting Kit-8 (CCK-8). Clonal ability was measured by colony formation assay. Cell apoptosis was determined via flow cytometry. Cell migration and invasion were assessed by transwell assay. Detection of protein was completed using western blot. Xenograft assay was used for the functional analysis of circ-CCS in vivo. The binding between targets was proved by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. E2F7 protein level was also examined by Immunohistochemistry (IHC) analysis in human tissues.

RESULTS

Circ-CCS was upregulated in lung cancer and could predict poor prognosis. Downregulation of circ-CCS inhibited lung cancer cell growth and metastasis while promoted apoptosis in vitro, and suppressed tumorigenesis of lung cancer in vivo. Circ-CCS had sponge effect on miR-383 and the function of si-circ-CCS was achieved by upregulating miR-383. E2F7 was a target gene of miR-383 and its downregulation was responsible for the anti-cancerous role of miR-383 in lung cancer. Circ-CCS could elevate E2F7 expression via interacting with miR-383.

CONCLUSION

Circ-CCS was shown to facilitate lung cancer progression via the miR-383/E2F7 axis, exhibiting the pivotal value of circ-CCS in diagnosis and treatment of lung cancer.

LncRNA FAM83H-AS1 maintains intervertebral disc tissue homeostasis and attenuates inflammation-related pain via promoting nucleus pulposus cell growth through miR-22-3p inhibition

Background

Intervertebral disc degeneration (IVDD) is regarded as the leading cause of low back pain, resulting in disability and a heavy burden on public health. Several studies have unveiled that long noncoding RNAs (lncRNAs) play a key role in the pathogenesis and progression of IVDD. In this study, we aimed to investigate the biological function and latent molecular mechanism of the lncRNA FAM83H antisense RNA 1 (FAM83H-AS1) in IVDD development.

Methods

Firstly, we established an IVDD model in rats using advanced glycation end products (AGEs) intradiscal injection. Subsequently, gain-of-function assays were conducted to investigate the role of FAM83H-AS1 in the progression of IVDD. Bioinformatics analysis, RNA pull down assay and rescue experiments were employed to shed light on the molecular mechanism underlying FAM83H-AS1 involving in IVDD.

Results

Our findings verified that AGEs treatment aggravated IVDD damage, and FAM83H-AS1 was downregulated in the IVDD group. Additionally, overexpression of FAM83H-AS1 contributed to the growth of nucleus pulposus (NP) cells and ameliorated IVDD injury. It was revealed that FAM83H-AS1 possessed the speculated binding sites of miR-22-3p. More importantly, we confirmed that FAM83H-AS1 functioned as a sponge of miR-22-3p in IVDD. Lastly, we demonstrated that miR-22-3p mediated the impact of FAM83H-AS1 on cell proliferation, ECM degradation, and inflammation.

Conclusions

Our study indicated that FAM83H-AS1 relieved IVDD deterioration through sponging miR-22-3p, and provides novel insights into the mechanisms underlying FAM83H-AS1 in IVDD progression.

Emerging evidence on noncoding-RNA regulatory machinery in intervertebral disc degeneration: a narrative review

Intervertebral disc degeneration (IDD) is the most common cause of low-back pain. Accumulating evidence indicates that the expression profiling of noncoding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long noncoding RNAs (lncRNAs), are different between intervertebral disc tissues obtained from healthy individuals and patients with IDD. However, the roles of ncRNAs in IDD are still unclear until now. In this review, we summarize the studies concerning ncRNA interactions and regulatory functions in IDD. Apoptosis, aberrant proliferation, extracellular matrix degradation, and inflammatory abnormality are tetrad fundamental pathologic phenotypes in IDD. We demonstrated that ncRNAs are playing vital roles in apoptosis, proliferation, ECM degeneration, and inflammation process of IDD. The ncRNAs participate in underlying mechanisms of IDD in different ways. MiRNAs downregulate target genes’ expression by directly binding to the 3′-untranslated region of mRNAs. CircRNAs and lncRNAs act as sponges or competing endogenous RNAs by competitively binding to miRNAs and regulating the expression of mRNAs. The lncRNAs, circRNAs, miRNAs, and mRNAs widely crosstalk and form complex regulatory networks in the degenerative processes. The current review presents novel insights into the pathogenesis of IDD and potentially sheds light on the therapeutics in the future.

A Bioinformatic Analysis of MicroRNAs' Role in Human Intervertebral Disc Degeneration

Objectives The aim of our study was to ascertain the underlying role of microRNAs (miRNAs) in human intervertebral disc degeneration (IDD). Design Bioinformatic analysis from multiple databases. Methods Studies of the association of miRNAs and IDD were identified in multiple electronic databases. All potential studies were assessed by the same inclusion and exclusion criteria. We recorded whether miRNA expression was commonly increased or suppressed in the intervertebral disc tissues and cells of IDD subjects. We used String to identify biological process and cellular component pathways of differentially expressed genes. Results We included fifty-seven articles from 1,277 records in this study. This report identified 40 different dysregulated miRNAs in 53 studies, including studies examining cell apoptosis (26 studies, 49.06%), cell proliferation (15 studies, 28.3%), extracellular matrix (ECM) degradation (10 studies, 18.86%), and inflammation (five studies, 9.43%) in IDD patients. Three upregulated miRNAs (miR-19b, miR-32, miR-130b) and three downregulated miRNAs (miR-31, miR-124a, miR-127-5p) were considered common miRNAs in IDD tissues. The top three biological process pathways for upregulated miRNAs were positive regulation of biological process, nervous system development, and negative regulation of biological process, and the top three biological process pathways for downregulated miRNAs were negative regulation of gene expression, intracellular signal transduction, and negative regulation of biological process. Conclusions This study revealed that miRNAs could be novel targets for preventing IDD and treating patients with IDD by regulating their target genes. These results provide valuable information for medical professionals, IDD patients, and health care policy makers.

miRNA-141 Induced Pyroptosis in Intervertebral Disk Degeneration by Targeting ROS Generation and Activating TXNIP/NLRP3 Signaling in Nucleus Pulpous Cells

The role and mechanism of pyroptosis in intervertebral disk (IVD) degeneration are unclear. MicroRNAs (miRNAs) regulate the viability and function of nucleus pulposus cells (NPCs) in IVDs and are related to pyroptosis. We performed microarray analyses of normal and degenerated nucleus pulposus (NP) to assess the role of pyroptosis and identify key miRNAs in IVD degeneration. We also evaluated the underlying mechanism of miRNA-mediated pyroptosis in NPCs. In addition, we demonstrated the preventative effects of miRNAs on IVD degeneration in a rat model. The levels of the pyroptosis-related proteins cleaved caspase-1, N-terminal gasdermin D (GSDMD), interleukin (IL)-1β, and IL-18 in the degenerative NP were significantly higher than those in the normal NP. miRNA-141 was significantly upregulated in the degenerated NP. miR-141 mimic suppressed the matrix synthesis function of NPCs. By contrast, reactive oxygen species (ROS) generation, and the expression of TXNIP and NLRP3 were significantly downregulated by an miR-141 inhibitor. Furthermore, the miRNA-141 inhibitor prevented the degeneration of IVDs in vivo. Our findings suggest that miRNA-141 induces pyroptosis and extracellular matrix (ECM) catabolism in NPCs by increasing ROS generation and activating TXNIP/NLRP3 signaling. miRNA-141-regulated pyroptosis may be a novel therapeutic target for IVD degeneration.

Cell Senescence: A Nonnegligible Cell State under Survival Stress in Pathology of Intervertebral Disc Degeneration

The intervertebral disc degeneration (IDD) with increasing aging mainly manifests as low back pain (LBP) accompanied with a loss of physical ability. These pathological processes can be preliminarily interpreted as a series of changes at cellular level. In addition to cell death, disc cells enter into the stagnation with dysfunction and deteriorate tissue microenvironment in degenerative discs, which is recognized as cell senescence. During aging, many intrinsic and extrinsic factors have been proved to have strong connections with these cellular senescence phenomena. Growing evidences of these connections require us to gather up critical cues from potential risk factors to pathogenesis and relative interventions for retarding cell senescence and attenuating degenerative changes. In this paper, we try to clarify another important cell state apart from cell death in IDD and discuss senescence-associated changes in cells and extracellular microenvironment. Then, we emphasize the role of oxidative stress and epigenomic perturbations in linking risk factors to cell senescence in the onset of IDD. Further, we summarize the current interventions targeting senescent cells that may exert the benefits of antidegeneration in IDD.

Silencing of Long Non-coding RNA NEAT1 Upregulates miR-195a to Attenuate Intervertebral Disk Degeneration via the BAX/BAK Pathway

Background/Aims

An increasing body of evidence has demonstrated that long non-coding RNAs (lncRNAs) play a vital regulatory role in intervertebral disk degeneration (IVDD). Nucleus enriched abundant transcript 1 (NEAT1), a novel cancer-related lncRNA, is associated with many malignancies, including ovarian cancer, and esophageal squamous cell carcinoma. Nevertheless, the role of NEAT1 in the progression of IVDD remains to be studied. Here, we explored the effect of NEAT1 on the progression of IVDD and the mechanisms involved.

Methods

An IVDD model was constructed in SD rats in vivo, and degeneration was induced by advanced glycation end product (AGE) in human nucleus pulposus cells (HNPC) in vitro. Quantitative real-time PCR was performed to detect the relative NEAT1 and miR-195a expressions and further confirmed the relationship between NEAT1 and miR-195a. Cell apoptosis was evaluated by TUNEL assay. The related mechanisms were explored by Western blot assay.

Results

The relative NEAT1 expression was significantly upregulated in the IVDD rat model and the denatured HNPC. Silencing of NEAT1 expression in HNPC significantly promoted the Collagen II and TIMP-1 expression induced by AGE while greatly suppressing the expressions of MMP-3 and cleaved caspase-3. Besides, downregulation of NEAT1 obviously reversed the AGE-induced apoptosis in HNPC. More interestingly, these effects of NEAT1 knockout on HNPC were largely reversed by silencing of miR-195a or overexpression of BAX under the AGE treatment. Mechanically, the direct combination of NEAT1 with miR-195a resulted in upregulation of MMP-3, cleaved caspase-3, BAX, and BAK, as well as downregulation of Collagen II and TIMP-1, which are associated with EMT and apoptosis. We also demonstrated similar results in the in vivo experiments.

Conclusion

NEAT1 played its role in IVDD progression via partly by mediating the miR-195 expression and might be used as a potential target for IVDD therapy.

LncRNA H19 Overexpression Activates Wnt Signaling to Maintain the Hair Follicle Regeneration Potential of Dermal Papilla Cells

Androgenetic alopecia (AGA) is a common hair loss disorder resulting in seriously abnormal social interaction and psychological disorders. Transplantation with autologous dermal papilla cells represents a prospective therapy. However, the ability of dermal papilla cells to induce hair follicle development is lost upon cell culturing. Long non-coding RNAs (lncRNAs) are an important class of genes involved in various biological functions, are aberrantly expressed in disease and may play roles in the regulation of Wnt signaling, a critical pathway in maintaining the hair follicle-inducing capability of dermal papilla cells. Examination of dermal papilla cells by lncRNA microarray revealed that H19 was highly expressed in early passage dermal papilla cells compared with late-passage dermal papilla cells. In this study, we constructed H19-overexpressing dermal papilla cells to examine the role of H19 on hair follicle inductivity. Dermal papilla cells infected with lentivirus encoding H19 maintained their cell shape, and continued to display both multiple-layer aggregation and hair follicle-inducing ability upon prolonged culture. H19 exerted these effects through inducing miR-29a to activate Wnt signaling by directly downregulating the expression of Wnt suppressors, including DKK1, Kremen2, and sFRP2, thereby forming a novel regulatory feedback loop between H19 and miR-29a to maintain hair follicle- inducing potential. These results suggest that lncRNA H19 maintains the hair follicle-inducing ability of dermal papilla cells through activation of the Wnt pathway and could be a target for treatment of androgenetic alopecia.

LncRNA TRPC7-AS1 regulates nucleus pulposus cellular senescence and ECM synthesis via competing with HPN for miR-4769-5p binding

Intervertebral disc (IVD) degeneration (IDD) is identified as an abnormal, cell-mediated, age-dependent and genetics-dependent molecular degeneration process in which NPCs (nucleus pulposus cells) senesce and the balance of ECM (extracellular matrix) synthesis and catabolism is disrupted. Increasing evidence reveals that IDD can be modulated by genetic factors, including non-coding RNAs. In the present study, we downloaded non-coding RNA profiling (GSE56081 and GSE63492) and performed GO annotation and enrichment analysis and association analyses on differentially-expressed genes. LncRNA TRPC7-AS1, miR-4769-5p, and Hepsin (HPN) may form a lncRNA-miRNA-mRNA network that can regulate NPC proliferation, senescence and ECM in IDD. LncRNA TRPC7-AS1 directly targets miR-4769-5p while miR-4769-5p directly targets HPN 3'UTR. miR-4769-5p overexpression inhibited HPN expression, suppressed NPC senescence, promoted NPC viability, and promoted ECM synthesis. The effect of TRPC7-AS1 silence on NPCs was similar as miR-4769-5p overexpression while the effect of HPN overexpression was opposite to miR-4769-5p overexpression. miR-4769-5p suppression or HPN overexpression could significantly attenuate the effect of TRPC7-AS1 silence. LncRNA TRPC7-AS1 relieves miR-4769-5p-induced inhibition on HPN via acting as a ceRNA, thus regulating NPC viability, senescence, and ECM synthesis. In summary, we regard lncRNA-miRNA-mRNA modulation as a new potent target for IDD treatment.

The circular RNA 001971/miR-29c-3p axis modulates colorectal cancer growth, metastasis, and angiogenesis through VEGFA

Background

Colorectal cancer (CRC) is one of the most common malignant tumors globally. Angiogenesis is a key event maintaining tumor cell survival and aggressiveness. The expression of vascular endothelial growth factor A (VEGFA), one of the most significant tumor cell-secreted proangiogenic factors, is frequently upregulated in CRC.

Methods

The MTT assay was used to detect the viability of CRC cells. Transwell assays were performed to detect the invasion capacity of target cells. Relative protein levels were determined by immunoblotting. Pathological characteristics of tissues were detected by H&E staining and immunohistochemical (IHC) staining. A RIP assay was conducted to validate the predicted binding between genes.

Results

We observed that circ-001971 expression was dramatically increased in CRC tissue samples and cells. Circ-001971 knockdown suppressed the capacity of CRC cells to proliferate and invade and HUVEC tube formation in vitro, as well as tumor growth in mice bearing SW620 cell-derived tumors in vivo. The expression of circ-001971 and VEGFA was dramatically increased whereas the expression of miR-29c-3p was reduced in tumor tissue samples. Circ-001971 relieved miR-29c-3p-induced inhibition of VEGFA by acting as a ceRNA, thereby aggravating the proliferation, invasion and angiogenesis of CRC. Consistent with the above findings, the expression of VEGFA was increased, whereas the expression of miR-29c-3p was decreased in tumor tissue samples. miR-29c-3p had a negative correlation with both circ-001971 and VEGFA, while circ-001971 was positively correlated with VEGFA.

Conclusions

In conclusion, the circ-001971/miR-29c-3p axis modulated CRC cell proliferation, invasion, and angiogenesis by targeting VEGFA.

H19 Increases IL-17A/IL-23 Releases via Regulating VDR by Interacting with miR675-5p/miR22-5p in Ankylosing Spondylitis

Long non-coding RNA (lncRNA) H19 is associated with inflammatory diseases, but the molecular mechanism of H19 in the inflammatory process of ankylosing spondylitis (AS) is unclear. Here, we investigated the role of H19 and its downstream molecules in the inflammation of AS by microarray analysis, qRT-PCR, western blot, and dual-luciferase reporter assay. H19 small interfering RNA (siRNA) (Si-H19) and adenovirus (AD-H19) were used to decrease and increase H19 expression, respectively. 42 annotated lncRNAs were identified, and H19 was overexpressed. H19, vitamin D receptor (VDR), and transforming growth factor β (TGF-β) can bind to microRNA22-5p (miR22-5p) and miR675-5p. Si-H19 significantly downregulated miR22-5p and upregulated miR675-5p expression; Si-H19 decreased the protein and mRNA expression of VDR and decreased the cytokine and mRNA levels of interleukin-17A (IL-17A) and IL-23. These results were verified by AD-H19. In addition, miR22-5p and miR675-5p inhibitors increased the protein and mRNA expression of VDR and increased the cytokine and mRNA levels of IL-17A and IL-23. These results were also confirmed by miRNA mimics. Furthermore, H19 directly interfered with miR22-5p and miR675-5p expression, whereas the two miRNAs directly inhibited VDR expression. Overall, the H19-miR22-5p/miR675-5p-VDR-IL-17A/IL-23 signaling pathways have important roles in the pathogenesis of AS.

The osteogenic differentiation of human adipose-derived stem cells is regulated through the let-7i-3p/LEF1/β-catenin axis under cyclic strain

Background

The Wnt/β-catenin pathway is involved in the osteogenic differentiation of human adipose-derived stem cells (hASCs) under cyclic strain. Very little is known about the role of microRNAs in these events.

Methods

Cells were obtained using enzyme digestion methods, and proliferation was detected using Cell Counting Kit 8. Cell cycles and immunophenotypes were detected by flow cytometry. The multilineage potential of hASCs was induced by induction media. Cyclic strain was applied to hASCs (0.5 Hz, 2 h/day, 6 days) to induce osteogenic differentiation and miRNA changes. Bioinformatic and dual-luciferase analyses confirmed lymphoid enhancer factor 1 (LEF1) as a potential target of let-7i-3p. The effect of let-7i-3p on LEF1 in hASCs transfected with a let-7i-3p mimic and inhibitor was analyzed by immunofluorescence. hASCs were transfected with a let-7i-3p mimic, inhibitor, or small interfering RNA (siRNA) against LEF1 and β-catenin. Quantitative real-time PCR (qPCR) and western blotting were performed to examine the osteogenic markers and Wnt/β-catenin pathway at the mRNA and protein levels, respectively. Immunofluorescence and western blotting were performed to confirm the activation of the Wnt/β-catenin pathway.

Results

Flow cytometry showed that 82.12% ± 5.83% of the cells were in G1 phase and 17.88% ± 2.59% of the cells were in S/G2 phase; hASCs were positive for CD29, CD90, and CD105. hASCs could have the potential for osteogenic, chondrogenic, and adipogenic differentiation. MicroRNA screening via microarray showed that let-7i-3p expression was decreased under cyclic strain. Bioinformatic and dual-luciferase analyses confirmed that LEF1 in the Wnt/β-catenin pathway was the target of let-7i-3p. Under cyclic strain, the osteogenic differentiation of hASCs was promoted by overexpression of LEF1and β-catenin and inhibited by overexpression of let-7i-3p. hASCs were transfected with let-7i-3p mimics and inhibitor. Gain- or loss-of-function analyses of let-7i-3p showed that the osteogenic differentiation of hASCs was promoted by decreased let-7i-3p expression and inhibited by increased let-7i-3p expression. Furthermore, high LEF1 expression inactivated the Wnt/β-catenin pathway in let-7i-3p-enhanced hASCs. In contrast, let-7i-3p inhibition activated the Wnt/β-catenin pathway.

Conclusions

Let-7i-3p, acting as a negative regulator of the Wnt/β-catenin pathway by targeting LEF1, inhibits the osteogenic differentiation of hASCs under cyclic strain in vitro.

LncRNA H19 ameliorates myocardial infarction-induced myocardial injury and maladaptive cardiac remodelling by regulating KDM3A

Myocardial infarction (MI) remains the leading cause of morbidity and mortality worldwide, and novel therapeutic targets still need to be investigated to alleviate myocardial injury and the ensuing maladaptive cardiac remodelling. Accumulating studies have indicated that lncRNA H19 might exert a crucial regulatory effect on cardiovascular disease. In this study, we aimed to explore the biological function and molecular mechanism of H19 in MI. To investigate the biological functions of H19, miRNA-22-3p and KDM3A, gain- and loss-of-function experiments were performed. In addition, bioinformatics analysis, dual-luciferase reporter assays, RNA immunoprecipitation (RIP) assays, RNA pull-down assays, quantitative RT-PCR and Western blot analyses as well as rescue experiments were conducted to reveal an underlying competitive endogenous RNA (ceRNA) mechanism. We found that H19 was significantly down-regulated after MI. Functionally, enforced H19 expression dramatically reduced infarct size, improved cardiac performance and alleviated cardiac fibrosis by mitigating myocardial apoptosis and decreasing inflammation. However, H19 knockdown resulted in the opposite effects. Bioinformatics analysis and dual-luciferase assays revealed that, mechanistically, miR-22-3p was a direct target of H19, which was also confirmed by RIP and RNA pull-down assays in primary cardiomyocytes. In addition, bioinformatics analysis and dual-luciferase reporter assays also demonstrated that miRNA-22-3p directly targeted the KDM3A gene. Moreover, subsequent rescue experiments further verified that H19 regulated the expression of KDM3A to ameliorate MI-induced myocardial injury in a miR-22-3p-dependent manner. The present study revealed the critical role of the lncRNAH19/miR-22-3p/KDM3A pathway in MI. These findings suggest that H19 may act as a potential biomarker and therapeutic target for MI.

Long non-coding RNA HOTAIR modulates intervertebral disc degenerative changes via Wnt/β-catenin pathway

BACKGROUND

Intervertebral disc degeneration (IDD) has a complicated and enigmatic pathogenic process. Accumulating evidence shows that long non-coding RNAs (LncRNAs) play a role in the pathogenesis of IDD. This study aimed to investigate the expression and role of the LncRNA HOTAIR in IDD pathogenesis.

METHODS

Nucleus pulposus (NP) tissue samples from 10 patients with idiopathic scoliosis and 10 patients with lumbar disc herniation were collected. qRT-PCR was used to assess the expression of HOTAIR and ECM-related genes; western blotting was used to detect the expression of senescence biomarkers, apoptosis-related proteins, and Wnt/β-catenin pathway; flow cytometry was used to detect apoptosis; and the MTT assay was used to determine cell proliferation. Moreover, a classic needle-punctured rat tail model was used to investigate the role of HOTAIR in IDD in vivo.

RESULTS

The results showed that the expression of HOTAIR significantly increased during IDD progression. The overexpression of HOTAIR was found to induce nucleus pulposus (NP) cell senescence, apoptosis, and extracellular matrix (ECM) degradation. HOTAIR silencing by RNA interference in NP cells prevented interleukin-1β-induced NP cell senescence, apoptosis, and ECM degradation. Furthermore, we found that the Wnt/β-catenin pathway played a role in regulating HOTAIR to induce these changes in NP cells. Moreover, HOTAIR inhibition in a rat model effectively attenuated IDD symptoms in vivo.

CONCLUSIONS

Our findings confirmed that HOTAIR promoted NP cell senescence, apoptosis, and ECM degradation via the activation of the Wnt/β-catenin pathway, while silencing HOTAIR attenuated this degeneration process, indicating a potential therapeutic target against IDD.

LncRNA-H19 promotes hepatic lipogenesis by directly regulating miR-130a/PPARγ axis in non-alcoholic fatty liver disease

Background: As one of the most common liver disorders worldwide, non-alcoholic fatty liver disease (NAFLD) begins with the abnormal accumulation of triglyceride (TG) in the liver. Long non-coding RNA-H19 was reported to modulate hepatic metabolic homeostasis in NAFLD. However, its molecular mechanism of NAFLD was not fully clear.Methods:In vitro and in vivo models of NAFLD were established by free fatty acid (FFA) treatment of hepatocytes and high-fat feeding mice, respectively. Hematoxylin and Eosin (H&E) and Oil-Red O staining detected liver tissue morphology and lipid accumulation. Immunohistochemistry (IHC) staining examined peroxisome proliferator-activated receptor γ (PPARγ) level in liver tissues. ELISA assay assessed TG secretion. Luciferase assay and RNA pull down were used to validate regulatory mechanism among H19, miR-130a and PPARγ. The gene expression in hepatocytes and liver tissues was detected by quantitative real-time PCR (qRT-PCR) and Western blotting.Results: H19 and PPARγ were up-regulated, while miR-130a was down-regulated in NAFLD mouse and cellular model. H&E and Oil-Red O staining indicated an increased lipid accumulation. Knockdown of H19 inhibited steatosis and TG secretion in FFA-induced hepatocytes. H19 could bind to miR-130a, and miR-130a could directly inhibit PPARγ expression. Meanwhile, miR-130a inhibited lipid accumulation by down-regulating NAFLD-related genes PPARγ, SREBP1, SCD1, ACC1 and FASN. Overexpression of miR-130a and PPARγ antagonist GW9662 inhibited lipogenesis and TG secretion, and PPARγ agonist GW1929 reversed this change induced by miR-130a up-regulation.Conclusion: Knockdown of H19 alleviated hepatic lipogenesis via directly regulating miR-130a/PPARγ axis, which is a novel mechanistic role of H19 in the regulation of NAFLD.

LncRNAs Regulatory Networks in Cellular Senescence

Long noncoding RNAs (lncRNAs) are a class of transcripts longer than 200 nucleotides with no open reading frame. They play a key role in the regulation of cellular processes such as genome integrity, chromatin organization, gene expression, translation regulation, and signal transduction. Recent studies indicated that lncRNAs are not only dysregulated in different types of diseases but also function as direct effectors or mediators for many pathological symptoms. This review focuses on the current findings of the lncRNAs and their dysregulated signaling pathways in senescence. Different functional mechanisms of lncRNAs and their downstream signaling pathways are integrated to provide a bird’s-eye view of lncRNA networks in senescence. This review not only highlights the role of lncRNAs in cell fate decision but also discusses how several feedback loops are interconnected to execute persistent senescence response. Finally, the significance of lncRNAs in senescence-associated diseases and their therapeutic and diagnostic potentials are highlighted.