Downregulated LncRNA-ANCR promotes osteoblast differentiation by targeting EZH2 and regulating Runx2 expression

Long non-coding RNAs in bone formation: Key regulators and therapeutic prospects

Recent scientific investigations have revealed the intricate mechanisms underlying bone formation, emphasizing the essential role of long non-coding RNAs (lncRNAs) as critical regulators. This process, essential for skeletal strength and functionality, involves the transformation of mesenchymal stem cells into osteoblasts and subsequent deposition of bone matrix. lncRNAs, including HOX transcript antisense RNA (HOTAIR), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), differentiation antagonizing non-coding RNA (DANCR), and maternally expressed gene 3 (MEG3), have emerged as prominent players in this regulatory network. HOTAIR modulates osteoblast differentiation by interacting with chromatin-modifying enzymes, while MALAT1 regulates osteogenic differentiation through microRNA interactions. DANCR collaborates with Runx2 to fine-tune osteoblast differentiation, and MEG3 orchestrates multiple signaling pathways crucial for bone formation. Moreover, other lncRNAs such as H19, lncRNA for enhancing osteogenesis 3, rhabdomyosarcoma 2-associated transcript, urothelial cancer associated 1, taurine up-regulated gene 1, and nuclear enriched abundant transcript 1 contribute to the complex regulatory network governing osteoblast activities. Understanding the precise roles of these lncRNAs offers promising avenues for developing innovative therapeutic strategies targeting bone-related disorders like osteoporosis. Overall, this review summarizes the pivotal role of lncRNAs in bone formation, highlighting their potential as targets for future research endeavors aimed at advancing therapeutic interventions in bone diseases.

Advances of long non-coding RNAs in osteoclast differentiation and osteoporosis

INTRODUCTION

Osteoclasts, which are responsible for bone resorption, are specialized multinucleated cells generated from monocyte/macrophage progenitor cells or hematopoietic stem cells (HSCs). Physiological bone remodeling can become pathological, such as osteoporosis, when osteoclastogenesis is out of balance. Thousands of long noncoding RNAs (lncRNAs) influence important molecular and biological processes. Recent research has revealed gene expression regulation function that numerous lncRNAs regulate nuclear domain organization, genome stability. Furthermore, the research of lncRNAs has substantial clinical implications for the treatment of existing and new diseases.

AREAS COVERED

In this review, we gather the most recent research on lncRNAs and their potential for basic research and clinical applications in osteoclast and osteoporosis. We also discuss the findings here in order to fully understand the role of lncRNAs in osteoclast differentiation and osteoporosis, as well as to provide a solid basis for future research exploring associated mechanisms and treatments.

EXPERT OPINION

LncRNA has been considered as an important role in the regulation of osteoclast differentiation and osteoporosis. It is exciting to investigate pathophysiological processes in osteoporosis and the therapeutic potential of lncRNAs. We hope that this review will offer promising prospects for the development of precision and individualized approaches to treatment.

N6-Methyladenosine in Cell-Fate Determination of BMSCs: From Mechanism to Applications

The methylation of adenosine base at the nitrogen-6 position is referred to as "N6-methyladenosine (m6A)" and is one of the most prevalent epigenetic modifications in eukaryotic mRNA and noncoding RNA (ncRNA). Various m6A complex components known as "writers," "erasers," and "readers" are involved in the function of m6A. Numerous studies have demonstrated that m6A plays a crucial role in facilitating communication between different cell types, hence influencing the progression of diverse physiological and pathological phenomena. In recent years, a multitude of functions and molecular pathways linked to m6A have been identified in the osteogenic, adipogenic, and chondrogenic differentiation of bone mesenchymal stem cells (BMSCs). Nevertheless, a comprehensive summary of these findings has yet to be provided. In this review, we primarily examined the m6A alteration of transcripts associated with transcription factors (TFs), as well as other crucial genes and pathways that are involved in the differentiation of BMSCs. Meanwhile, the mutual interactive network between m6A modification, miRNAs, and lncRNAs was intensively elucidated. In the last section, given the beneficial effect of m6A modification in osteogenesis and chondrogenesis of BMSCs, we expounded upon the potential utility of m6A-related therapeutic interventions in the identification and management of human musculoskeletal disorders manifesting bone and cartilage destruction, such as osteoporosis, osteomyelitis, osteoarthritis, and bone defect.

Dancr-BRG1 regulates Nfatc1 transcription and Pgc1β-dependent metabolic shifts in osteoclastogenesis

Long non-coding RNA (lncRNA) serves as a vital regulator of bone metabolism, but its role in pathologically overactive osteoclast differentiation remains elusive. Here, we identify lncRNA Dancr (Differentiation Antagonizing Non-protein Coding RNA) as a critical suppressor of osteoclastogenesis and bone resorption, which is down-regulated in response to estrogen deficiency. Global or osteoclast-specific Dancr Knockout mice display significant trabecular bone deterioration and enhanced osteoclast activity, but minimal alteration of bone formation. Moreover, the bone-targeted delivery of Dancr by Adeno-associated viral remarkably attenuates ovariectomy-induced osteopenia in mice. Mechanistically, Dancr establishes a direct interaction with Brahma-related gene 1 to prevent its binding and preserve H3K27me3 enrichment at the nuclear factor of activated T cells 1 and proliferator-activated receptor gamma coactivator 1-beta promoters, thereby maintaining appropriate expression of osteoclastic genes and metabolic programs during osteoclastogenesis. These results demonstrate that Dancr is a key molecule maintaining proper osteoclast differentiation and bone homeostasis under physiological conditions, and Dancr overexpression constitutes a potential strategy for treating osteoporosis.

HOTAIR knockdown impairs metastasis of cervical cancer cells by down-regulating metastasis-related genes

This study investigated the role of LncRNA HOTAIR knockdown in the biological impacts on cervical cancer cells. The HOTAIR gene in two human cervical cancer cell lines was silenced with small interfering (si) RNA siHOTAIR. Proliferation, apoptosis, migration and invasion of cells were assessed following the knockdown. The expressions of Notch1, EpCAM, E-cadherin, vimentin and STAT3 were assessed using qRT-PCR and Western blotting analysis. Compared with controls, HOTAIR levels were reduced significantly, the OD values of cells were significantly decreased in proliferation assays, cell apoptosis was significantly increased, cell migration and invasion were significantly reduced after HOTAIR knockdown. Molecular analysis showed that Notch1, EpCAM, vimentin and STAT3 expressions were decreased significantly, while the expression of E-cadherin was significantly increased after HOTAIR knockdown. Rescue experiments further confirmed that Notch1 and STAT3 were involved in siHOTAIR-mediated reduction of migration and invasion of cervical cancer cells.IMPACT STATEMENTWhat is already known on this subject? Long non-coding RNAs including HOTAIR, is implicated in occurrence and development of cancer and have been explored to develop new therapeutic options for cancer.What do the results of this study add? HOTAIR silencing significantly reduces the viability and migration ability of cells and induces cell apoptosis, adding experimental data supporting the potential use of HOTAIR specific-siRNA as a therapeutic avenue for the cancer.What are the implications of these findings for clinical practice and/or further research? The finding from this study would help develop clinically applicable therapeutic avenues for the cancer and identify new treatment targets in the relevant pathways leading to new drugs or treatments.

N6-methyladenosine-mediated overexpression of long noncoding RNA ADAMTS9-AS2 triggers neuroblastoma differentiation via regulating LIN28B/let-7/MYCN signaling

Neuroblastomas have shed light on the differentiation disorder that is associated with spontaneous regression or differentiation in the same tumor at the same time. Long noncoding RNAs (lncRNAs) actively participate in a broad spectrum of biological processes. However, the detailed molecular mechanisms underlying lncRNA regulation of differentiation in neuroblastomas remain largely unknown. Here, we sequenced clinical samples of ganglioneuroma, ganglioneuroblastoma, and neuroblastoma. We compared transcription profiles of neuroblastoma cells, ganglion cells, and intermediate state cells; verified the profiles in a retinoic acid-induced cell differentiation model and clinical samples; and screened out the lncRNA ADAMTS9 antisense RNA 2 (ADAMTS9-AS2), which contributed to neuroblastoma differentiation. ADAMTS9-AS2 upregulation in neuroblastoma cell lines inhibited proliferation and metastatic potential. Additional mechanistic studies illustrated that the interactions between ADAMTS9-AS2 and LIN28B inhibited the association between LIN28B and primary let-7 (pri-let-7) miRNA, then released pri-let-7 into cytoplasm to form mature let-7, resulting in the inhibition of oncogene MYCN activity that subsequently affected cancer stemness and differentiation. Furthermore, we showed that the observed differential expression of ADAMTS9-AS2 in neuroblastoma cells was due to N6-methyladenosine methylation. Finally, ADAMTS9-AS2 upregulation inhibited proliferation and cancer stem-like capabilities in vivo. Taken together, these results show that ADAMTS9-AS2 loss leads to malignant neuroblastoma by increasing metastasis and causing dysfunctional differentiation.

Engineered exosomes reprogram Gli1+ cells in vivo to prevent calcification of vascular grafts and autologous pathological vessels

Calcification of autologous pathological vessels and tissue engineering blood vessels (TEBVs) is a thorny problem in clinic. However, there is no effective and noninvasive treatment that is available against the calcification of TEBVs and autologous pathological vessels. Gli1+ cells are progenitors of smooth muscle cells (SMCs) and can differentiate into osteoblast-like cells, leading to vascular calcification. Our results showed that the spatiotemporal distribution of Gli1+ cells in TEBVs was positively correlated with the degree of TEBV calcification. An anticalcification approach was designed consisting of exosomes derived from mesenchymal stem cells delivering lncRNA-ANCR to construct the engineered exosome-Ancr/E7-EXO. The results showed that Ancr/E7-EXO effectively targeted Gli1+ cells, promoting rapid SMC reconstruction and markedly inhibiting Gli1+ cell differentiation into osteoblast-like cells. Moreover, Ancr/E7-EXO significantly inhibited vascular calcification caused by chronic kidney disease. Therefore, Ancr/E7-EXO reprogrammed Gli1+ cells to prevent calcification of vascular graft and autologous pathological vessel, providing unique insights for an effective anticalcification.

Differential Expression of Non-Coding RNAs in Stem Cell Development and Therapeutics of Bone Disorders

Stem cells' self-renewal and multi-lineage differentiation are regulated by a complex network consisting of signaling factors, chromatin regulators, transcription factors, and non-coding RNAs (ncRNAs). Diverse role of ncRNAs in stem cell development and maintenance of bone homeostasis have been discovered recently. The ncRNAs, such as long non-coding RNAs, micro RNAs, circular RNAs, small interfering RNA, Piwi-interacting RNAs, etc., are not translated into proteins but act as essential epigenetic regulators in stem cells' self-renewal and differentiation. Different signaling pathways are monitored efficiently by the differential expression of ncRNAs, which function as regulatory elements in determining the fate of stem cells. In addition, several species of ncRNAs could serve as potential molecular biomarkers in early diagnosis of bone diseases, including osteoporosis, osteoarthritis, and bone cancers, ultimately leading to the development of new therapeutic strategies. This review aims to explore the specific roles of ncRNAs and their effective molecular mechanisms in the growth and development of stem cells, and in the regulation of osteoblast and osteoclast activities. Furthermore, we focus on and explore the association of altered ncRNA expression with stem cells and bone turnover.

Biological and Mechanical Factors and Epigenetic Regulation Involved in Tendon Healing

Tendons are an important part of the musculoskeletal system. Connecting muscles to bones, tendons convert force into movement. Tendon injury can be acute or chronic. Noticeably, tendon healing requires a long time span and includes inflammation, proliferation, and remodeling processes. The mismatch between endogenous and exogenous healing may lead to adhesion causing further negative effects. Management of tendon injuries and complications such as subsequent adhesion formation are still challenges for clinicians. Due to numerous factors, tendon healing is a complex process. This review introduces the role of various biological and mechanical factors and epigenetic regulation processes involved in tendon healing.

Exosomes in bone remodeling and breast cancer bone metastasis

Exosomes are endosome-derived microvesicles that carry cell-specific biological cargo, such as proteins, lipids, and noncoding RNAs (ncRNAs). They play a key role in bone remodeling by enabling the maintenance of a balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Recent evidence indicates that exosomes disrupt bone remodeling that occurs during breast cancer (BC) progression. The bone is a preferred site for BC metastasis owing to its abundant osseous reserves. In this review, we aimed to highlight the roles of exosomes derived from bone cells and breast tumor in bone remodeling and BC bone metastasis (BCBM). We also briefly outline the mechanisms of action of ncRNAs and proteins carried by exosomes secreted by bone and BCBM. Furthermore, this review highlights the potential of utilizing exosomes as biomarkers or delivery vehicles for the diagnosis and treatment of BCBM.

Roles of LINC01473 and CD74 in osteoblasts in multiple myeloma bone disease

The suppression of osteoblast (OB) activity is partially responsible for multiple myeloma (MM) bone disease. Long non-coding RNAs (lncRNAs) play a vital role in bone formation and resorption. However, their functions in OBs from patients with MM have rarely been reported. Through high-throughput sequencing of OBs from patients with MM and healthy controls, we identified several lncRNAs and messenger RNAs (mRNAs) with different expression profile and validated them using quantitative real-time PCR. In total, 22 upregulated and 21 downregulated lncRNAs were found in OBs from patients with MM. Moreover, 18 upregulated protein-coding mRNAs were identified. The expression levels of LINC01473 and its associated co-expression mRNA, CD74, were higher in patients with MM than in healthy controls (p=0.047 and p=0.016, respectively). LINC01473 expression demonstrated a negative correlation with serum interleukin-2 and tumor necrosis factor α levels, whereas the expression of mRNA CD74 was positively associated with serum lactic dehydrogenase in patients with MM. Aberrant expression of lncRNAs and mRNAs was observed in OBs from patients with MM. This study identifies new promising targets for further research on imbalanced bone formation and resorption and MM immune escape.

LINC01119 negatively regulates osteogenic differentiation of mesenchymal stem cells via the Wnt pathway by targeting FZD4

Background

Mesenchymal stem cells (MSCs) can differentiate into diverse cell types under specific conditions. Dysfunction in the osteogenic differentiation of MSCs can result in bone metabolism-related diseases, including osteoporosis. Accumulating evidence has revealed that long non-coding RNA (lncRNAs) play critical regulatory roles during MSC differentiation.

Methods

In the present study, we identified an evolutionarily conserved lncRNA expressed during the osteogenic differentiation of MSCs, which we termed LINC01119. We first identified LINC01119 as a negative regulator of the osteogenic differentiation of MSCs.

Results

LINC01119 knockdown markedly induced calcium deposition in bone marrow MSCs and promoted the osteogenic differentiation of MSCs. More importantly, we demonstrated the underlying molecular basis through which LINC01119 regulates osteogenesis via the Wnt pathway by targeting FZD4. Furthermore, we observed that transcription factor EBF3 could directly bind the promoter site of LINC01119.

Conclusions

We first explored the molecular regulatory mechanism of LINC01119 during the osteogenic differentiation of MSCs and revealed that LINC01119 negatively regulates osteogenesis through the Wnt pathway by targeting FZD4.

Role of lncRNAs into Mesenchymal Stromal Cell Differentiation

Currently, findings support that 75% of the human genome is actively transcribed, but only 2% is translated into a protein, according to databases such as ENCODE (Encyclopedia of DNA Elements) [1]. The development of high-throughput sequencing technologies, computational methods for genome assembly and biological models have led to the realization of the importance of the previously unconsidered non-coding fraction of the genome. Along with this, noncoding RNAs have been shown to be epigenetic, transcriptional and post-transcriptional regulators in a large number of cellular processes [2]. Within the group of non-coding RNAs, lncRNAs represent a fascinating field of study, given the functional versatility in their mode of action on their molecular targets. In recent years, there has been an interest in learning about lncRNAs in MSC differentiation. The aim of this review is to address the signaling mechanisms where lncRNAs are involved, emphasizing their role in either stimulating or inhibiting the transition to differentiated cell. Specifically, the main types of MSC differentiation are discussed: myogenesis, osteogenesis, adipogenesis and chondrogenesis. The description of increasingly new lncRNAs reinforces their role as players in the well-studied field of MSC differentiation, allowing a step towards a better understanding of their biology and their potential application in the clinic.

Skin-Expressing lncRNAs in Inflammatory Responses

Long non-coding RNAs (lncRNAs) have attracted attention for their potential roles in modulating keratinocyte differentiation and inflammatory response; however, for many identified skin-expressing lncRNAs, there is no comprehensive characterization regarding their biological roles. In addition, the reported expression profiles for lncRNAs can be ambiguous due to their low-expressing nature. The objective of this review is to utilize large scale genomic data to characterize the prominent skin-expressing lncRNAs, aiming to provide additional insights for their potential roles in the pathology of inflammatory skin of psoriasis and atopic dermatitis by integrating in vitro and in vivo data. We highlighted the different skin-expressing lncRNAs, including H19, which is significantly down-regulated in lesional skin of AD/psoriasis and upon cytokine stimulation in keratinocytes; it is also negatively correlated with CYP1A1 (r = -0.75, p = 8 × 10^-73), a gene involved in drug metabolism and skin barrier homeostasis, in keratinocytes. In addition, SPRR2C, a potential regulator that modulates IL-22 stimulation, was upregulated in both atopic dermatitis and psoriasis lesional skin and was also downstream of the IL-17A and IL-17 + TNF signaling in keratinocytes. Using scRNAseq, we further revealed the cell type specificity of lncRNAs, including basal-expressing nature of H19 in the epidermis. Interestingly, instead of having cell type specific expression profile, we found few lncRNAs that are express across different cell types in skin, including MALAT1, NEAT1, and GAS5. While lncRNAs in general have lower expression, our results combining in vitro and in vivo experimental data demonstrate how some of these lncRNAs can play mediator roles in the cytokine-stimulated pathway.

Epigenetic modifications of histones during osteoblast differentiation

In bone biology, epigenetics plays a key role in mesenchymal stem cells' (MSCs) commitment towards osteoblasts. It involves gene regulatory mechanisms governed by chromatin modulators. Predominant epigenetic mechanisms for efficient osteogenic differentiation include DNA methylation, histone modifications, and non-coding RNAs. Among these mechanisms, histone modifications critically contribute to altering chromatin configuration. Histone based epigenetic mechanisms are an essential mediator of gene expression during osteoblast differentiation as it directs the bivalency of the genome. Investigating the importance of histone modifications in osteogenesis may lead to the development of epigenetic-based remedies for genetic disorders of bone. Hence, in this review, we have highlighted the importance of epigenetic modifications such as post-translational modifications of histones, including methylation, acetylation, phosphorylation, ubiquitination, and their role in the activation or suppression of gene expression during osteoblast differentiation. Further, we have emphasized the future advancements in the field of epigenetics towards orthopaedical therapeutics.

LncRNA MALAT1 promotes osteogenic differentiation of BMSCs and inhibits osteoclastic differentiation of Mø in osteoporosis via the miR-124-3p/IGF2BP1/Wnt/β-catenin axis

Osteoporosis is defined as a skeletal disorder characterized by impairment in bone strength. The potential application of lncRNAs as therapeutic targets for osteoporosis has been unveiled. This study investigated the regulatory mechanism of lncRNA MALAT1 in the differentiation of bone marrow stem cells (BMSCs) and macrophages (Mø) in osteoporosis. MALAT1 expression in peripheral blood of elderly osteoporosis patients and healthy volunteers was detected. BMSCs and mononuclear Mø were isolated and cultured. Osteogenic differentiation of BMSCs and osteoclastic differentiation of Mø were induced. BMSCs and Mø were transfected with si-MALAT1, miR-124-3p mimics, miR-124-3p inhibitor, or pcDNA IGF2BP1, followed by detection of cell differentiation. The target microRNAs (miRs) and downstream genes and signaling pathways of MALAT1 were examined. The ovariectomy-induced mouse model of osteoporosis was established, and the mice were injected with pcDNA-MALAT1. MALAT1 was downregulated in osteoporosis patients, increased in BMSCs after osteogenic differentiation, and diminished in Mø after osteoclastic differentiation. Downregulation of MALAT1 repressed osteogenic differentiation of BMSCs and facilitated osteoclastic differentiation of Mø. MALAT1 upregulated IGF2BP1 expression by competitively binding to miR-124-3p. miR-124-3p silencing reversed the effect of si-MALAT1 on BMSCs and Mø differentiation, and IGF2BP1 upregulation averted the effect of overexpressed-miR-124-3p by activating the Wnt/β-catenin pathway. Upregulation of MALAT1 activated the Wnt/β-catenin pathway and attenuated bone injury in mice. In conclusion, lncRNA MALAT1 promoted the osteogenic differentiation of BMSCs and inhibited osteoclastic differentiation of Mø in osteoporosis via the miR-124-3p/IGF2BP1/Wnt/β-catenin axis. This article is protected by copyright. All rights reserved.

LncRNA SNHG1 modulates adipogenic differentiation of BMSCs by promoting DNMT1 mediated Opg hypermethylation via interacting with PTBP1

Recent evidence indicates that the abnormal differentiation of bone marrow‐derived mesenchymal stem cells (BMSCs) plays a pivotal role in the pathogenesis of osteoporosis. LncRNA SNHG1 has been found to be associated with the differentiation ability of BMSCs. In this study, we aimed to elucidate the role of lncRNA SNHG1 and its associated pathway on the differentiation of BMSCs in osteoporosis. Mice that underwent bilateral ovariectomy (OVX) were used as models of osteoporosis. Induced osteogenic or adipogenic differentiation was performed in mouse BMSCs. Compared to sham animals, lncRNA SNHG1 expression was upregulated in OVX mice. Also, the in vitro expression of SNHG1 was increased in adipogenic BMSCs but decreased in osteogenic BMSCs. Moreover, overexpression of SNHG1 enhanced the adipogenic capacity of BMSCs but inhibited their osteogenic capacity as determined by oil red O, alizarin red, and alkaline phosphatase staining, while silencing of SNHG1 led to the opposite results. LncRNA SNHG1 interacting with the RNA‐binding polypyrimidine tract‐binding protein 1 (PTBP1) promoted osteoprotegerin (Opg) methylation and suppressed Opg expression via mediating DNA methyltransferase (DNMT) 1. Furthermore, Opg was showed to regulate BMSC differentiation. Knockdown of SNHG1 decreased the expressions of adipogenic related genes but increased that of osteogenic related genes. However, the knockdown of Opg partially reversed those effects. In summary, lncRNA SNHG1 upregulated the expression of DNMT1 via interacting with PTBP1, resulting in Opg hypermethylation and decreased Opg expression, which in turn enhanced BMSC adipogenic differentiation and contributed to osteoporosis.

The control of polycomb repressive complexes by long noncoding RNAs

The polycomb repressive complexes 1 and 2 (PRCs; PRC1 and PRC2) are conserved histone-modifying enzymes that often function cooperatively to repress gene expression. The PRCs are regulated by long noncoding RNAs (lncRNAs) in complex ways. On the one hand, specific lncRNAs cause the PRCs to engage with chromatin and repress gene expression over genomic regions that can span megabases. On the other hand, the PRCs bind RNA with seemingly little sequence specificity, and at least in the case of PRC2, direct RNA-binding has the effect of inhibiting the enzyme. Thus, some RNAs appear to promote PRC activity, while others may inhibit it. The reasons behind this apparent dichotomy are unclear. The most potent PRC-activating lncRNAs associate with chromatin and are predominantly unspliced or harbor unusually long exons. Emerging data imply that these lncRNAs promote PRC activity through internal RNA sequence elements that arise and disappear rapidly in evolutionary time. These sequence elements may function by interacting with common subsets of RNA-binding proteins that recruit or stabilize PRCs on chromatin. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

The regulation mechanism of LINC00707 on the osteogenic differentiation of human periodontal ligament stem cells

The osteogenic differentiation of periodontal ligament stem cells (PDLSCs) is important for periodontal tissue repair and regeneration. Long non-coding RNAs (lncRNAs) are key regulators of diverse biological processes. However, their roles in PDLSC osteogenic differentiation are still largely unknown. This study explored the effect of LINC00707 and its mechanism on the osteogenic differentiation of human PDLSCs. Results showed an increase in LINC00707 and forkhead box O1 (FOXO1) but a decrease in miR-490-3p during PDLSC osteogenic differentiation. LINC00707 and FOXO1 promoted osteogenic differentiation as evidenced by the formation of calcium nodules and the increase in osteogenic markers such as alkaline phosphatase, osteocalcin (OCN), and runt-related transcription factor 2 (Runx2). LINC00707 and FOXO1 knockdown exhibited opposite effects. Dual-luciferase reporter assay and qRT-PCR showed that LINC00707 can specially bind to miR-490-3p, which reversed the effect of LINC00707 on PDLSCs. MiR-490-3p inhibitor relieved the inhibiting effect of sh-LINC00707 on osteogenic differentiation. Further investigation revealed that LINC00707 can promote osteogenic differentiation by regulating FOXO1 expression through miR-490-3p sponging. Thus, the LINC00707/miR-490-3p/FOXO1 axis modulated PDLSC osteogenic differentiation and might be a promising therapeutic target for periodontal diseases.

Bone Marrow-Derived Mesenchymal Stem Cells (BMSCs)-Derived MicroRNA-378a-3p (miR-378a-3p) Inhibits the Migration of Gestational Trophoblast Cells and Epithelial Mesenchymal Transition via Regulating X-Linked Inhibitor of Apoptosis Protein (XIAP) Pathway

The components of the in vivo microenvironment are BMSCs and miRNAs that have a critical role in the development of pregnancy. Our aim was to further investigate the effect of the miRNAs of BMSC origin on pregnancy injury. Exosomal miR-378a-3p secreted by BMSCs was identified by electron microscopy and miR-378a-3p expression was measured during gestational injury. Target scan detects the correlation of XIAP and miR-378a-3p which was confirmed by luciferase activity along with analysis of cell growth by MTT assay and cell invasion by Transwell and EMT expression. Exosomal miR-378a-3p derived from BMSCs promoted proliferation and migration and invasion of trophoblast. miR-378a-3p targeted XIAP and its overexpression could significantly increase EMT switching. The miR-378a-3p/XIAP axis is critical in trophoblastic cell migration and EMT and is involved in pregnancy injury progression, indicating that it might be a novel potential target for the treatment of pregnancy injury.

lncRNA GAS5 regulates angiogenesis by targeting miR‑10a‑3p/VEGFA in osteoporosis

Osteoporosis is a severe bone disease commonly occurring in older males and postmenopausal females. Previous studies have shown that long non‑coding (lnc)RNA growth arrest‑specific 5 (GAS5) serves an important role in osteoporosis. However, its role is unclear and requires further exploration. The relative expression levels of GAS5 and miR‑10a‑3p in the serum samples of patients with osteoporosis, as well as the relative expression levels of GAS5, microRNA (miR)‑10a‑3p and vascular endothelial growth factor A (VEGFA) mRNA in osteoblasts, were detected by reverse transcription‑quantitative PCR. ELISA and western blotting were used to detect the expression levels of VEGFA. A Matrigel angiogenesis test was used to assess the effects on angiogenesis. RNA binding interactions between GAS5/miR‑10a‑3p and miR‑10a‑3p/VEGFA were evaluated using dual‑luciferase reporter assays. Furthermore, the effects of the GAS5/miR‑10a‑3p/VEGFA axis were investigated via ELISA, western blotting and Matrigel angiogenesis. GAS5 was significantly downregulated and miR‑10a‑3p was upregulated in patients with osteoporosis. Overexpression of GAS5 promoted angiogenesis. GAS5 acted as a sponge of miR‑10a‑3p; VEGFA was a target gene of miR‑10a‑3p. GAS5 induced angiogenesis by inhibiting miR‑10a‑3p and enhancing VEGFA expression. These results indicated that GAS5 overexpression increased angiogenesis by inhibiting miR‑10a‑3p, promoting the expression of VEGFA. The present study revealed a novel mechanism and provided novel targets for the clinical treatment of osteoporosis.

Contribution of miRNAs and lncRNAs in osteogenesis and related disorders

Non-coding RNAs have been found to regulate several developmental processes among them is osteogenesis. Although these transcripts have several distinct classes, two classes i.e. microRNAs and long non-coding RNAs have attained more attention. These transcripts regulate intramembranous as well as endochondral ossification processes. The effects of microRNAs on osteogenesis are mostly mediated through modulation of Wnt/β-catenin and TGFβ/BMP pathways. Long non-coding RNAs can directly affect expression of these pathways or osteogenic transcription factors. Moreover, they can serve as a molecular sponge for miRNAs. MALAT1/miR-30, MALAt1/miR-214, LEF1-AS1/miR-24-3p, MCF2L-AS1/miR-33a, MSC-AS1/miR-140-5p and KCNQ1OT1/miR-214 are examples of such kind of interaction between lncRNAs and miRNAs in the context of osteogenesis. In the current paper, we explain these two classes of non-coding RNAs in the osteogenesis and related disorders.

miR-1 Activates NF-κB to Promote the Differentiation of Bone Marrow Mesenchymal Stem Cells in Mouse Models of Glioma

NF-κB activation and its abnormal expression are involved in the progression of glioma. miRNA plays a crucial role in bone diseases. The role of NF-κB is becoming more and more important. The purpose of this study is to explore the mechanism by how miR-1 regulates NF-κB signaling. C57 glioma mouse models were divided into osteoporosis (OP) group and control group. qPCR was used to measure miR-1 levels in OP and control mice. Bone marrow mesenchymal stem cells (BMSCs) were cultured and transfected with miR-1 specific siRNA to establish miR-1 knockout cell model followed by analysis of cell apoptosis, expression of NF-κB signaling molecules by western blot. qPCR results showed that miR-1 levels in OP mice were significantly reduced compared to control mice. A large number of siRNA particles were observed in transfected BMSCs under a fluorescence microscope. qPCR results showed that siRNA transfection significantly suppressed miR-1, indicating successful transfection. Flow cytometry revealed significant differences in cell apoptosis between miR-1 siRNA group and the NC group. Western blot indicated miR-1 promoted BMSCs differentiation via NF-κB mediated up-regulation of ALP activity. The expression of miR-1 is low in BMSCs of mice with glioma. In addition, BMSCs differentiation is enhanced by NF-κB activation via up-regulating miR-1.

The Roles of Long Non-coding RNA in Osteoporosis

The Human Genome Project (HGP) announced in 2001 that it had sequenced the entire human genome, yielding nearly complete human DNA. About 98.5 percent of the human genome has been found to be non-coding sequences. Long non-coding RNA (lncRNA) is a non-coding RNA with a length between 200 and 100,000 nucleotide units. Because of shallow research on lncRNA, it was believed that it had no biological functions, but exists as a by-product of the transcription process. With the development of high-throughput sequencing technology, studies have shown that lncRNA plays important roles in many processes by participating in epigenetics, transcription, translation and protein modification. Current researches have shown that lncRNA also has an important part in the pathogenesis of osteoporosis. Osteoporosis is a common disorder of bone metabolism, also a major medical and socioeconomic challenge worldwide. It is characterized by a systemic reduction in bone mass and microstructure changes, which increases the risk of brittle fractures. It is more common in postmenopausal women and elderly men. However, the roles of lncRNA and relevant mechanisms in osteoporosis remain unclear. Based on this background, we hereby review the roles of lncRNA in osteoporosis, and how it influences the functions of osteoblasts and osteoclasts, providing reference to clinical diagnosis, treatment and prognosis of osteoporosis.

The Role of LncRNA H19 in MAPK Signaling Pathway Implicated in the Progression of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD), also known as neonatal chronic lung disease, is an important cause of respiratory illness in preterm newborns that results in significant morbidity and mortality. Long noncoding RNAs (lncRNAs) have been discovered with many biological functions. However, the role of lncRNAs in the pathogenesis of BPD remains poorly understood. Here, we established a mouse lung injury model that mimicked human BPD. Subsequently, we found the lncRNA H19 expression level was significantly increased in BPD compared with normal lung tissues using quantitative real-time polymerase chain reaction. Next, we observed that overexpression of lncRNA H19 enhanced mitogen-activated protein kinase (MAPK) signaling pathway. In addition, we also found that dysfunction of lncRNA H19 altered the expression of inflammatory factors. Thus, our study validates that lncRNA H19 contributes to the progression of BPD by regulating MAPK signaling pathway, which could be used as a potential target for treating BPD.

Osteoblast Differentiation and Signaling: Established Concepts and Emerging Topics

Osteoblasts, the cells that build up our skeleton, are remarkably versatile and important cells that need tight regulation in all the phases of their differentiation to guarantee proper skeletal development and homeostasis. Although we know many of the key pathways involved in osteoblast differentiation and signaling, it is becoming clearer and clearer that this is just the tip of the iceberg, and we are constantly discovering novel concepts in osteoblast physiology. In this review, we discuss well-established pathways of osteoblastic differentiation, i.e., the classical ones committing mesenchymal stromal cells to osteoblast, and then osteocytes as well as recently emerged players. In particular, we discuss micro (mi)RNAs, long non-coding (lnc)RNAs, circular (circ)RNAs, and extracellular vesicles, focusing on the mechanisms through which osteoblasts are regulated by these factors, and conversely, how they use extracellular vesicles to communicate with the surrounding microenvironment.

LncRNA Nron Inhibits Bone Resorption in Periodontitis

Periodontitis is the most common chronic oral disease and is characterized by active osteoclast activity and significant alveolar bone resorption. However, the key regulatory factors of periodontal bone loss have yet to be determined, and reasonable intervention methods for periodontitis have not been developed. Currently, long noncoding RNAs (lncRNAs) have shown a remarkable ability to maintain normal cell and tissue homeostasis. Interestingly, we recently found that the lncRNA Nron is negatively correlated with alveolar bone resorption in periodontitis model. To explore the role of Nron in periodontal bone loss, osteoclastic-specific Nron knockout mice and osteoclastic-specific Nron transgenic mice were generated. Nron effectively inhibited osteoclastogenesis and alveolar bone resorption. Mechanistically, Nron was found to effectively promote the nuclear transport of NF-κb repressing factor (NKRF). In addition, NKRF in the nucleus significantly repressed the transcription of Nfatc1, which is a major NF-κb signaling molecule. Importantly, local injection of the Nron overexpression vector significantly inhibited osteoclastogenesis and alveolar bone resorption, which indicated the translational application potential of lncRNAs in the treatment of bone resorption in periodontitis.

The potential role of lncRNAs in osteoporosis

Osteoporosis is a common bone disease characterized by low bone mass and deterioration of bone microstructure, which predisposes to higher risks of bone fragility and bone fracture. Long non-coding RNAs (lncRNAs) are a class of RNAs with a length of > 200 nucleotides without protein-coding function, which control the expression of genes and affect multiple biological processes. Accumulating evidence suggests that lncRNAs are widely involved in the molecular mechanisms of osteoporosis. This review aims to summarize the function and underlying mechanism of lncRNAs involved in the development of osteoporosis, and how it contributes to osteoblast and osteoclast function. This knowledge will shed new light on the modulation and potential treatment of osteoporosis.

Analysis of crucial genes, pathways and construction of the molecular regulatory networks in vascular smooth muscle cell calcification

Vascular calcification (VC) accompanies the trans-differentiation of vascular smooth muscle cells (VSMCs) into osteo/chondrocyte-like cells and resembles physiological bone mineralization. However, the molecular mechanisms underlying VC initiation and progression have remained largely elusive. The aim of the present study was to identify the genes and pathways common to VSMC and osteoblast calcification and construct a regulatory network of non-coding RNAs and transcription factors (TFs). To this end, the Gene Expression Omnibus dataset GSE37558 including mRNA microarray data of calcifying VSMCs (CVSMCs) and calcifying osteoblasts (COs) was analyzed. The differentially expressed genes (DEGs) were screened and functionally annotated and the microRNA (miRNA/mRNA)-mRNA, TF-miRNA and long non-coding RNA (lncRNA)-TF regulatory networks were constructed. A total of 318 DEGs were identified in the CVSMCs relative to the non-calcified VSMCs, of which 43 were shared with the COs. The CVSMC-related DEGs were mainly enriched in the functional terms cell cycle, extracellular matrix (ECM), inflammation and chemotaxis-mediated signaling pathways, of which ECM was enriched by the DEGs for the COs as well. The protein-protein interaction network of CVSMCs consisted of 281 genes and 3,650 edges. There were 30 hub genes in this network, including maternal embryonic leucine zipper kinase (MELK), which potentially regulates the differentially expressed TF (DETF) forkhead box (FOX)M1 and is a potential target gene of Homo sapiens miR-485-3p and miR-181d. The TF-miRNA network included 251 TFs and 60 miRNAs, including 10 DETFs such as FOXO1 and snail family transcriptional repressor 2 (SNAI2). Furthermore, the lncRNAs H19 imprinted maternally expressed transcript (H19) and differentiation antagonizing non-protein coding RNA (DANCR) were predicted as the upstream regulators of FOXO1 and SNAI2 in the lncRNA-TF regulatory network. DANCR, MELK and FOXM1 were downregulated, and H19, FOXO1 and SNAI2 were upregulated in the CVSMCs. Taken together, the CVSMCs and COs exhibited similar molecular changes in the ECM. In addition, the MELK-FOXM1, H19/DANCR-FOXO1 and SNAI2 regulatory pathways likely mediate VSMC calcification.

Experimental Study of lncRNA RP11-815M8.1 Promoting Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Objective

This study is aimed at investigating the role of long noncoding RNA (lncRNA) RP11-815M8.1 in the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs).

Methods

RT-PCR was used to detect the expression of lncRNA RP11-815M8.1 before and after osteogenic differentiation of hBMSCs. The lncRNA RP11-815M8.1 in hBMSCs was overexpressed or silenced via lentiviral transfection. The transfection efficiency was detected by RT-PCR, and the proliferation of hBMSCs was determined by CCK-8. After 14 days of osteogenic differentiation of transfected hBMSCs, the expression of osteogenic transcription factors (ALP, OCN, OPN, Runx2, and Osterix) was detected by alizarin red staining and RT-PCR. The mRNAs directly regulated by lncRNA RP11-815M8.1 and targeted miRNAs were analyzed according to the positional relationship between lncRNA and mRNA in the genome and miRanda software.

Results

The expression of lncRNA RP11-815M8.1 enhanced with increasing osteogenic differentiation time of hBMSCs. Two days after the transfection of hBMSCs, lncRNA RP11-815M8.1 expression was significantly increased in the overexpression group and significantly decreased in the knockdown group, compared to control cells. The CCK-8 assay showed that overexpression and knockdown of lncRNA RP11-815M8.1 did not affect the proliferation of hBMSCs. After 14 days of differentiation of hBMSCs, stronger alizarin red staining was observed in the overexpression groups, and the expression of osteogenic transcription factors was increased in the overexpression group compared to the control. In the knockdown group, alizarin red staining and the expression of osteogenic transcription factors were decreased. Bioinformatics analysis showed that lncRNA RP11-815M8.1 was directly associated with one mRNA, 27 interacting miRNAs, and 20 miRNA-targeted mRNAs.

Conclusion

The osteogenic differentiation of hBMSCs can be promoted by lncRNA RP11-815M8.1 in vitro.

Long non-coding RNA ADAMTS9-AS2 inhibits liver cancer cell proliferation, migration and invasion

Long non-coding RNA (lncRNA) ADAM metallopeptidase with thrombospondin type 1 motif 9 antisense RNA 2 (ADAMTS9-AS2) is involved in various types of cancer, such as ovarian cancer, lung cancer and clear cell renal cell carcinoma. However, the roles of ADAMTS9-AS2 in liver cancer are not completely understood. The present study aimed to determine the functional role of ADAMTS9-AS2 in human liver cancer and investigate the potential underlying molecular mechanisms. The expression levels of ADAMTS9-AS2 and ADAMTS9 were determined following ADAMTS9-AS2 overexpression and knockdown. The results indicated that ADAMTS9-AS2 overexpression and knockdown increased and decreased ADAMTS9 mRNA and protein expression levels, respectively, indicating that alterations in ADAMTS9 expression corresponded with ADAMTS9-AS2 expression. Subsequently, the effects of ADAMTS9-AS2 on liver cancer cell proliferation, migration and invasion were analyzed by performing Cell Counting Kit-8, wound healing and Transwell assays, respectively. The results demonstrated that ADAMTS9-AS2 inhibited liver cancer cell proliferation, migration and invasion. Finally, the effect of ADAMTS9 on PI3K/AKT/mTOR signaling pathway-associated proteins [AKT, phosphorylated-AKT, phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit β (PIK3CB), mTOR and phosphorylated-mTOR], several key autophagy-related proteins [light chain 3-I/II (LC3-I/II), beclin 1 (BECN1) and sequestosome 1 (SQSTM1)] and apoptosis-related proteins (Bax and Bcl-2) was detected via western blotting. The results suggested that ADAMTS9-AS2 downregulated the phosphorylation of AKT and mTOR, the protein expression level of PIK3CB, as well as the expression levels of autophagy protein SQSTM1 and antiapoptotic protein Bcl-2. By contrast, ADAMTS9-AS2 upregulated the expression levels of autophagy proteins LC3-II and BECN1, and the proapoptotic protein Bax. Collectively, ADAMTS9-AS2 inhibited liver cancer cell proliferation, migration and invasion via inhibiting the PI3K/AKT/mTOR signaling pathway. The present study provided a novel insight into the role of ADAMTS9-AS2 in liver cancer.

The Role of Noncoding RNAs in Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

Chronic inflammatory diseases, including periodontitis, are the most common causes of bone tissue destruction. Periodontitis often leads to loss of connective tissue homeostasis and reduced alveolar bone levels. Human periodontal ligament stem cells (PDLSCs), a population of multipotent stem cells derived from periodontal ligament tissues, are considered as candidate cells for the regeneration of alveolar bone and periodontal tissues. Periodontitis impairs the osteogenic differentiation of human PDLSCs. Noncoding RNAs (ncRNAs), including long noncoding RNA (lncRNA), microRNA (miRNA), and circular RNA (circRNA), have been proposed as vital regulators influencing several differentiation processes including bone regeneration. Still, the molecular mechanisms of ncRNAs regulating osteogenic differentiation of human PDLSCs remain poorly understood. Exploring the influence of ncRNAs in the process of osteogenic differentiation of human PDLSCs may provide novel therapeutic strategies for tissue regeneration as the regeneration of the lost periodontium is the ultimate goal of periodontal therapy.

The Roles of Epigenetics Regulation in Bone Metabolism and Osteoporosis

Osteoporosis is a metabolic disease characterized by decreased bone mineral density and the destruction of bone microstructure, which can lead to increased bone fragility and risk of fracture. In recent years, with the deepening of the research on the pathological mechanism of osteoporosis, the research on epigenetics has made significant progress. Epigenetics refers to changes in gene expression levels that are not caused by changes in gene sequences, mainly including DNA methylation, histone modification, and non-coding RNAs (lncRNA, microRNA, and circRNA). Epigenetics play mainly a post-transcriptional regulatory role and have important functions in the biological signal regulatory network. Studies have shown that epigenetic mechanisms are closely related to osteogenic differentiation, osteogenesis, bone remodeling and other bone metabolism-related processes. Abnormal epigenetic regulation can lead to a series of bone metabolism-related diseases, such as osteoporosis. Considering the important role of epigenetic mechanisms in the regulation of bone metabolism, we mainly review the research progress on epigenetic mechanisms (DNA methylation, histone modification, and non-coding RNAs) in the osteogenic differentiation and the pathogenesis of osteoporosis to provide a new direction for the treatment of bone metabolism-related diseases.

Involvement of the long noncoding RNA H19 in osteogenic differentiation and bone regeneration

Osteogenic differentiation and bone regeneration are complex processes involving multiple genes and multiple steps. In this review, we summarize the effects of the long noncoding RNA (lncRNA) H19 on osteogenic differentiation.

Osteogenic differentiation includes matrix secretion and calcium mineralization as hallmarks of osteoblast differentiation and the absorption of calcium and phosphorus as hallmarks of osteoclast differentiation. Mesenchymal stem cells (MSCs) form osteoprogenitor cells, pre-osteoblasts, mature osteoblasts, and osteocytes through induction and differentiation. lncRNAs regulate the expression of coding genes and play essential roles in osteogenic differentiation and bone regeneration. The lncRNA H19 is known to have vital roles in osteogenic induction.

This review highlights the role of H19 as a novel target for osteogenic differentiation and the promotion of bone regeneration.

LncRNA DANCR represses Doxorubicin-induced apoptosis through stabilizing MALAT1 expression in colorectal cancer cells

Long non-coding RNA (lncRNA) DANCR has been reported to participate in key processes such as stem cell differentiation and tumorigenesis. In a high throughput screening for lncRNAs involved in Doxorubicin-induced apoptosis, we found DANCR was suppressed by Doxorubicin and it acted as an important repressor of apoptosis in colorectal cancer. Further studies demonstrated that DANCR promoted the oncogenic lncRNA MALAT1 expression via enhancing the RNA stability of MALAT1 to suppress apoptosis. MALAT1 could efficiently mediate the suppressive function of DANCR on apoptosis. Mechanistic studies found the RNA-binding protein QK served as an interacting partner of both DANCR and MALAT1, and the protein level of QK was subjected to the regulation by DANCR. Furthermore, QK was able to modulate the RNA stability of MALAT1, and the interaction between QK and MALAT1 was controlled by DANCR. In addition, QK could mediate the function of DANCR in regulating the expression of MALAT1 and suppressing apoptosis. These results revealed DANCR played a critical role in Doxorubicin-induced apoptosis in colorectal cancer cells, which was achieved by the interaction between DANCR and QK to enhance the expression of MALAT1.

Emerging trends in chromatin remodeler plasticity in mesenchymal stromal cell function

Emerging evidences highlight importance of epigenetic regulation and their integration with transcriptional and cell signaling machinery in determining tissue resident adult pluripotent mesenchymal stem/stromal cell (MSC) activity, lineage commitment, and multicellular development. Histone modifying enzymes and large multi-subunit chromatin remodeling complexes and their cell type-specific plasticity remain the central defining features of gene regulation and establishment of tissue identity. Modulation of transcription factor expression gradient ex vivo and concomitant flexibility of higher order chromatin architecture in response to signaling cues are exciting approaches to regulate MSC activity and tissue rejuvenation. Being an important constituent of the adult bone marrow microenvironment/niche, pathophysiological perturbation in MSC homeostasis also causes impaired hematopoietic stem/progenitor cell function in a non-cell autonomous mechanism. In addition, pluripotent MSCs can function as immune regulatory cells, and they reside at the crossroad of innate and adaptive immune response pathways. Research in the past few years suggest that MSCs/stromal fibroblasts significantly contribute to the establishment of immunosuppressive microenvironment in shaping antitumor immunity. Therefore, it is important to understand mesenchymal stromal epigenome and transcriptional regulation to leverage its applications in regenerative medicine, epigenetic memory-guided trained immunity, immune-metabolic rewiring, and precision immune reprogramming. In this review, we highlight the latest developments and prospects in chromatin biology in determining MSC function in the context of lineage commitment and immunomodulation.

Long Noncoding RNA MALAT1 Promotes Colorectal Cancer Progression by Acting as a ceRNA of miR-508-5p to Regulate RAB14 Expression

Accumulating evidence suggested that lncRNA MALAT1 plays critical roles in the commencement and progression of malignant cancers. Nevertheless, the function of MALAT1 in colorectal cancer (CRC) remains largely unknown. In the present study, we reported that MALAT1 expression is significantly upregulated in CRC and correlated with advanced TNM stage, lymph node metastasis, and worse prognosis in patients. Functional assays revealed that MALAT1 knockdown reduced CRC cell growth and invasion abilities in vitro. Mechanistically, we discovered that MALAT1 may serve as a competing endogenous RNA (ceRNA) to miR-508-5p in CRC progression. Bioinformatics analysis and luciferase assays confirmed that RAB14 acts as a target of miR-508-5p. In addition, downregulation of RAB14 reduced the progression of CRC. Collectively, our findings indicated that MALAT1 could promote CRC progress by sponging miR-508-5p and enhancing RAB14 expression, which provides a therapeutic target in CRC treatment.

Silencing of long non-coding RNA LINC01270 inhibits esophageal cancer progression and enhances chemosensitivity to 5-fluorouracil by mediating GSTP1methylation

Esophageal cancer (EC) is a serious digestive malignancy which remains the sixth leading cause of cancer-related deaths worldwide. Emerging evidence suggests the involvement of long non-coding RNAs (lncRNAs) in the tumorigenesis of EC and thus, in this study we explored the potential effects of lncRNA LINC01270 on EC cell proliferation, migration, invasion and, drug resistance via regulation of glutathione S-transferase P1 (GSTP1) methylation. First, we screened out the EC-related differentially expressed lncRNAs, and the expression of our top candidate LINC01270 was quantified in EC tissues and cells. To define the role of LINC01270 in EC progression, we evaluated the proliferation, migration and invasion of EC cells when the LINC01270 was overexpressed or knocked down, in the presence of the GSTP1 methylation inhibitor SGI-1027 and 5-fluorouracil (5-FU). In addition, interaction between LINC01270 and methylation of the GSTP1 promoter was identified. Finally, we assessed transplantable tumor growth in nude mice. LINC01270 was up-regulated and GSTP1 was down-regulated in EC tissues and cells. Silencing of LINC01270 inhibited migration and invasion, and enhanced the sensitivity of 5-FU in EC cells. We found that LINC01270 recruited the DNA methyltransferases DNMT1, DNMT3A and DNMT3B initiating GSTP1 promoter methylation, thereby leading to the proliferation, migration, invasion and drug resistance of EC cells. Moreover, GSTP1 overexpression was observed to reverse the effects of LINC01270 overexpression on EC cells and their response to 5-FU. Taken together, this study shows that inhibition of LINC01270 can lead to suppression of EC progression via demethylation of GSTP1, highlighting this lncRNA as a potential target for EC treatment.

Long non-coding RNA XIST binding to let-7c-5p contributes to rheumatoid arthritis through its effects on proliferation and differentiation of osteoblasts via regulation of STAT3

BACKGROUND

Rheumatoid arthritis (RA), a chronic autoimmune disease, affects around 1% population worldwide, with the life quality of patients severely reduced. In this study, it is intended to explore the role of long non-coding RNA X-inactive specific transcript (lncRNA XIST) in RA and the underlying mechanisms associated with let-7c-5p and signal transducer and activator of transcription 3 (STAT3).

METHODS

LncRNA XIST, let-7c-5p, and STAT3 expressions were determined in RA and normal cartilage tissues, and their relationship was analyzed in osteoblasts. The regulatory effects of lncRNA XIST in RA were investigated when XIST expression was upregulated or downregulated in osteoblasts. TNF-α, IL-2, IL-6, alkaline phosphatase (ALP), osteocalcin, TGF-β1, and IGF1 were measured in vivo in RA rats.

RESULTS

LncRNA XIST and STAT3 were expressed at high levels and let-7c-5p expressed at a low level in RA cartilage tissues. LncRNA XIST silencing or let-7c-5p enhancement led to decreased levels of TNF-α, IL-2, and IL-6, suggestive of suppressed inflammatory response, and increased levels of ALP, osteocalcin, TGF-β1, and IGF-1 as well as reduced damage in cartilage tissues.

CONCLUSION

LncRNA XIST downregulation could promote proliferation and differentiation of osteoblasts in RA, serving as a future therapeutic target for RA.

Exosomal lncRNAs NONMMUT000375.2 and NONMMUT071578.2 derived from titanium particle treated RAW264.7 cells regulate osteogenic differentiation of MC3T3-E1 cells

Periprosthetic osteolysis and the subsequent aseptic loosening can lead to the failure of joint replacement. Wear particles are well known to be the initiative cause inducing osteolysis through enhancing osteoclast-mediated bone resorption and reducing osteogenic differentiation. The purpose of this study was to investigate the effects of osteoclast-secreted exosomal long noncoding RNAs (lncRNAs) on osteogenesis in the process of particle-induced osteolysis. RAW264.7 cells were treated by titanium particles (TI). The inflammatory cytokines were increased, and expression of Receptor Activator of Nuclear Factor-κB and Nuclear factor of activated T cells c1 were also increased, indicating osteoclast differentiation occurred. The purified exosomes from RAW264.7 cells induced with TI inhibited osteogenic differentiation of MC3T3-E1 cells. RNA sequencing generated lncRNAs expression profiles (458 up-regulated and 1641 down-regulated) of the exosomes derived from RAW264.7 cells treated with TI. Based on the results of gene ontology/Kyoto Encyclopedia of Genes and Genomes analysis and quantitative real time polymerase chain reaction validation, we confirmed two candidate lncRNAs, NONMMUT000375.2 and NONMMUT071578.2. The regulation network presented that some vital genes involved in osteoclast differentiation, such as Bcl2, Wnt11, TGF-β, and Pdk1, were under the regulation of NONMMUT000375.2 and NONMMUT071578.2. Taken together, exosomes derived from TI treated RAW264.7 cells inhibit the osteogenic activity of MC3T3-E1 cells. Exosomal lncRNAs, NONMMUT000375.2 and NONMMUT071578.2 may potentially play their roles in promoting osteoclast differentiation and suppressing osteogenesis, which aggravates the osteoclastogenesis/osteogenesis imbalance.

Genome-wide identification of lncRNAs and mRNAs differentially expressed in human vascular smooth muscle cells stimulated by high phosphorus

Background: Cardiovascular events are the primary cause of death for chronic kidney disease patients, which occurred via vascular calcification evolving pathogenically. Although a high level of phosphorus contributes to the induction of osteogenic differentiation of vascular smooth muscle cells (VSMCs), the role of lncRNA in this process awaits further study.Methods: In this study, we systematically investigated the variation of gene expression in human VSMCs induced by high phosphorus. LncRNAs and mRNAs expression were revealed by microarray analyses of the control group and high-phosphorus (HP) group. LncRNA-mRNA co-expression network was established based on the specific lncRNA-mRNA relationships. Hierarchical clustering was used to identify a common set of regulated genes. In addition, Gene Ontology enrichment, Kyoto Gene-Encyclopedia and genomic analyses were conducted for the mRNAs differentially expressed under high phosphorus.Result: RT-qPCR results confirmed that the expression of RUNX2, BMP2 and osteocalcin in HP group exhibited significant increases than in control group (p < .05). VSMC in HP group also showed higher intracellular calcium content. Volcano plots results show that 379 mRNAs and 728 lncRNAs different expressed in HP group. LncRNA-mRNA co-expression networks analysis revealed that 8 lncRNAs were the most highly connected lncRNAs. Quantitative analysis indicated that two lncRNAs were confirmed to increase significantly in the HP group. The mRNA expression of NT5E and ICAM1 were higher in group HP, while MAP3K7CL was lower than CON group (p < .05).Conclusion: This study provided a working list of lncRNAs that may be relevant to osteogenic differentiation, which presents a new insights into the mechanism of vascular calcification induced by high phosphorus in VSMCs.

Aberrant NSUN2-mediated m5C modification of H19 lncRNA is associated with poor differentiation of hepatocellular carcinoma

RNA methylation is an important epigenetic modification. Recent studies on RNA methylation mainly focus on the m⁶A modification of mRNA, but very little is known about the m⁵C modification. NSUN2 is an RNA methyltransferase responsible for the m⁵C modification of multiple RNAs. In this study, we knocked down the NSUN2 gene in HepG2 cells by CRISPR/Cas9 technology and performed high-throughput RNA-BisSeq. An important tumor-related lncRNA H19 was identified to be targeted by NSUN2. Studies have shown that the expression of H19 lncRNA is abnormally elevated and has a carcinogenic effect in many types of tumors. Our results demonstrated that m⁵C modification of H19 lncRNA can increase its stability. Interestingly, m⁵C-modified H19 lncRNA can be specifically bound by G3BP1, a well-known oncoprotein which further leads to MYC accumulation. This may be a novel mechanism by which lncRNA H19 exerts its oncogenic effect. Besides, both the m⁵C methylation level and the expression level of H19 lncRNA in hepatocellular carcinoma tissues were significantly higher than those in adjacent non-cancer tissues, which were closely associated with poor differentiation of hepatocellular carcinoma (HCC). In conclusion, we found that H19 RNA is a specific target for the NSUN2 modifier. The m⁵C-modified H19 lncRNA may promote the occurrence and development of tumors by recruiting the G3BP1 oncoprotein. Our findings may provide a potential target and biomarker for the diagnosis and treatment of HCC.

lncRNA Neat1 Stimulates Osteoclastogenesis Via Sponging miR-7

Increasing evidence uncover the essential role of long noncoding RNA (lncRNAs) in bone metabolism and the association of lncRNA with genetic risk of osteoporosis. However, whether lncRNA nuclear paraspeckle assembly transcript 1 (Neat1) is involved remains largely unknown. In the present study, we found that Neat1 is induced by osteoclastic differentiation stimuli. Knockdown of Neat1 attenuates osteoclast formation whereas overexpression of Neat1 accelerates osteoclast formation. In vivo evidence showed that enhanced Neat1 expression stimulates osteoclastogenesis and reduces bone mass in mice. Mechanically, Neat1 competitively binds with microRNA 7 (miR-7) and blocks its function for regulating protein tyrosine kinase 2 (PTK2). Intergenic SNP rs12789028 acts as allele-specific long-range enhancer for NEAT1 via chromatin interactions. We establish for the first time that Neat1 plays an essential role in osteoclast differentiation, and provide genetic mechanism underlying the association of NEAT1 locus with osteoporosis risk. These results enrich the current knowledge of NEAT1 function, and uncover the potential of NEAT1 as a therapeutic target for osteoporosis. © 2020 American Society for Bone and Mineral Research.

Identification and Characterization of MAPK Signaling Pathway Genes and Associated lncRNAs in the Ileum of Piglets Infected by Clostridium perfringens Type C

Clostridium perfringens type C (C. perfringens type C) is one of the main microbial pathogens responsible for piglet diarrhea worldwide, causing substantial economic losses for pig-rearing industries. The mitogen-activated protein kinase (MAPK) signaling pathway is a key regulator of inflammatory bowel disease, especially necrotic enteritis. However, whether and how the MAPK signaling pathway is involved in regulating the process of piglet diarrhea when challenged by C. perfringens type C are still unknown. Here, we screened 38 differentially expressed genes (DEGs) in piglets' ileum tissues experimentally infected with C. perfringens type C that were enriched in the Sus scrofa MAPK signaling pathway, based on our previous transcriptome data. Of these DEGs, 12 genes (TRAF2, MAPK8, and GADD45G, among others) were upregulated whereas 26 genes (MAPK1, TP53, and CHUK, among others) were downregulated in the infected group. Our results showed that MAPK1, TP53, MAPK8, MYC, and CHUK were in the core nodes of the PPI network. Additionally, we obtained 35 lncRNAs from the sequencing data, which could be trans-targeted to MAPK signaling pathway genes and were differentially expressed in the ileum tissues infected with C. perfringens. We used qRT-PCR to verify the expression levels of genes and lncRNAs related to the MAPK signaling pathway; their expression patterns were consistent with RNA sequencing data. Our results provide strong support for deeply exploring the role of the MAPK signaling pathway in diarrhea caused by C. perfringens type C.

LncRNA DANCR and miR-320a suppressed osteogenic differentiation in osteoporosis by directly inhibiting the Wnt/β-catenin signaling pathway

Our study aimed to determine how lncRNA DANCR, miR-320a, and CTNNB1 interact with each other and regulate osteogenic differentiation in osteoporosis. qRT-PCR and western blotting were performed to determine the expression of DANCR, miR-320a, CTNNB1, and the osteoporosis- or Wnt/β-catenin pathway-related markers T-cell factor 1 (TCF-1), runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). Interactions between CTNNB1, DANCR, and miR-320a were predicted by bioinformatics approaches and validated using a luciferase assay. Osteoblastic phenotypes were evaluated by ALP staining, ALP activity assay and Alizarin Red staining. The bilateral ovariectomy method was used to establish an in vivo osteoporosis model. Bone morphological changes were examined using hematoxylin and eosin (H&E) and Alcian Blue staining. The expression levels of DANCR and miR-320a in BMSCs derived from osteoporosis patients were upregulated, whereas CTNNB1 expression was downregulated compared with that in healthy controls. Importantly, we demonstrated that miR-320a and DANCR acted independently from each other and both inhibited CTNNB1 expression, whereas the inhibitory effect was additive when miR-320a and DANCR were cooverexpressed. Moreover, we found that DANCR overexpression largely abrogated the effect of the miR-320a inhibitor on CTNNB1 expression and the Wnt/β-catenin signaling pathway in BMSCs during osteogenic differentiation. We further confirmed the results above in BMSCs derived from an osteoporosis animal model. Taken together, our findings revealed that DANCR and miR-320a regulated the Wnt/β-catenin signaling pathway during osteogenic differentiation in osteoporosis through CTNNB1 inhibition. Our results highlight the potential value of DANCR and miR-320a as promising therapeutic targets for osteoporosis treatment.

Two non-coding RNAs are potential targets for reducing bone loss in post-menopausal osteoporosis. Bones are constantly being remodeled; when resorption outpaces generation of new bone, bones are weakened, causing osteoporosis and leading to decreased quality of life and injuries. Although treatments exist, they often have undesirable side effects, and new treatments are needed. The molecular basis of the changes that accompany osteoporosis are poorly understood. Da Zhong at the Xiangya Hospital of Central South University in Changsha, China, and co-workers investigated how two non-coding RNAs, small molecules that regulate gene expression, are involved in the progression of post-menopausal osteoporosis. They found that levels of both molecules are increased in osteoporosis, and that silencing them increases building of new bone, key to maintaining bone strength. These results illuminate a potential new direction in treatments for osteoporosis.

SNHG14 induces osteogenic differentiation of human stromal (mesenchymal) stem cells in vitro by downregulating miR-2861

BACKGROUND

The differentiation of human stromal (mesenchymal) stem cells (hMSCs) is a critical procedure for the development of osteoblast. SNHG14 is a newly discovered lncRNA that has been barely studied. Our preliminary experiments showed that SNHG14 may be dysregulated in the differentiation of hMSCs. In this study, we focused on elucidating the relationships among SNGH14, miR-2861, and osteoblastic differentiation of hMSCs.

METHOD

To investigate the roles of SNHG14 and miR2861 in hMSCs differentiation, qRT-PCR, luciferase activity, cell transfections, the detections of ALP activity, and Alizarin Red staining were performed.

RESULT

We found that the expression of SNHG14 was enhanced, while the expression of miR-2861 was suppressed in serum and hMSCs from patients with osteoporosis. SNHG14 could target miR-2861, and shSNHG14 suppressed osteoblast differentiation of hMSC. MiR-2861 suppressed osteoblast differentiation of hMSC. In addition, the effects of SNHG14 on osteoblast differentiation of hMSC were attenuated by miR-2861.

CONCLUSION

In conclusion, our experimental data showed that the induction effects of SNHG14 on osteoblast differentiation of hMSC were attenuated by miR-2861. SNHG14 could induce osteogenic differentiation of hMSC in vitro by targeting miR-2861.

RP11-480I12.5-004 Promotes Growth and Tumorigenesis of Breast Cancer by Relieving miR-29c-3p-Mediated AKT3 and CDK6 Degradation

Pseudogenes have been reported to exert oncogenic or tumor-suppressive functions in cancer. However, the expression, role, and mechanism of pseudogene-derived RNAs in breast cancer remain unclear. The RNA levels and prognostic values of pseudogenes in breast cancer were determined. The levels of RP11-480I12.5 in cell lines and clinical samples were validated by quantitative real-time PCR. In vitro effects of RP11-480I12.5 on cell growth were measured by cell counting kit-8 (CCK-8) assay, colony formation assay, cell counting assay, and flow cytometry analysis. Xenograft model was established to detect its in vivo effect. The potential mechanism of RP11-480I12.5 was also studied by a combination of bioinformatic analysis and experimental confirmation. Finally, the possible functional parental genes of RP11-480I12.5 in breast cancer were explored. After a series of bioinformatic analyses, RP11-480I12.5 was selected as the most potential pseudogene in breast cancer. RP11-480I12.5 expression was significantly upregulated in breast cancer cell lines and clinical breast cancer tissues. Knockdown of RP11-480I12.5 markedly suppressed cell proliferation and colony formation, induced cell apoptosis of breast cancer in vitro, and inhibited tumor growth in vivo. Four transcripts of RP11-480I12.5 (001/002/003/004) were identified. Only overexpression of RP11-480I12.5-004 significantly enhanced cell growth of breast cancer both in vitro and in vivo. RP11-480I12.5-004 mainly located in cytoplasm and increased AKT3 and CDK6 mRNA expression, at least in part, by competitively binding to miR-29c-3p. Six parental genes of RP11-480I12.5 were found, among which TUBA1B and TUBA1C were statistically linked to RP11-480I12.5 expression, possessed prognostic values, and were upregulated in breast cancer. Our findings suggested that pseudogene-derived long non-coding RNA (lncRNA) RP11-480I12.5-004 promoted growth and tumorigenesis of breast cancer via increasing AKT3 and CDK6 expression by competitively binding to miR-29c-3p.