LINC00473 regulated apoptosis, proliferation and migration but could not reverse cell cycle arrest of human bone marrow mesenchymal stem cells induced by a high-dosage of dexamethasone

Baicalin attenuates dexamethasone-induced apoptosis of bone marrow mesenchymal stem cells by activating the hedgehog signaling pathway

BACKGROUND

Perturbations in bone marrow mesenchymal stem cell (BMSC) differentiation play an important role in steroid-induced osteonecrosis of the femoral head (SONFH). At present, studies on SONFH concentrate upon the balance within BMSC osteogenic and adipogenic differentiation. However, BMSC apoptosis as well as proliferation are important prerequisites in their differentiation. The hedgehog (HH) signaling pathway regulates bone cell apoptosis. Baicalin (BA), a well-known compound in traditional Chinese medicine, can affect the proliferation and apoptosis of numerous cell types via HH signaling. However, the potential role and mechanisms of BA on BMSCs are unclear. Thus, we aimed to explore the role of BA in dexamethasone (Dex)-induced BMSC apoptosis in this study.

METHODS

Primary BMSCs were treated with 10 -6 mol/L Dex alone or with 5.0 μmol/L, 10.0 μmol/L, or 50.0 μmol/L BA for 24 hours followed by co-treatment with 5.0 μmol/L, 10.0 μmol/L, or 50.0 μmol/L BA and 10 -6 mol/L Dex. Cell viability was assayed through the Cell Counting Kit-8 (CCK-8). Cell apoptosis was evaluated using Annexin V-fluorescein isothiocyanate/propidium iodide (PI) staining followed by flow cytometry. The imaging and counting, respectively, of Hochest 33342/PI-stained cells were used to assess the morphological characteristics and proportion of apoptotic cells. To quantify the apoptosis-related proteins (e.g., apoptosis regulator BAX [Bax], B-cell lymphoma 2 [Bcl-2], caspase-3, and cleaved caspase-3) and HH signaling pathway proteins, western blotting was used. A HH-signaling pathway inhibitor was used to demonstrate that BA exerts its anti-apoptotic effects via the HH signaling pathway.

RESULTS

The results of CCK-8, Hoechst 33342/PI-staining, and flow cytometry showed that BA did not significantly promote cell proliferation (CCK-8: 0 μmol/L, 100%; 2.5 μmol/L, 98.58%; 5.0 μmol/L, 95.18%; 10.0 μmol/L, 98.11%; 50.0 μmol/L, 99.38%, F   =  2.33, P   >  0.05), but it did attenuate the effect of Dex on apoptosis (Hoechst 33342/PI-staining: Dex+ 50.0 μmol/L BA, 12.27% vs. Dex, 39.27%, t  = 20.62; flow cytometry: Dex + 50.0 μmol/L BA, 12.68% vs. Dex, 37.43%, t  = 11.56; Both P  < 0.05). The results of western blotting analysis showed that BA reversed Dex-induced apoptosis by activating the HH signaling pathway, which down-regulated the expression of Bax, cleaved-caspase 3, and suppressor of fused (SUFU) while up-regulating Bcl-2, sonic hedgehog (SHH), and zinc finger protein GLI-1 (GLI-1) expression (Bax/Bcl-2: Dex+ 50.0 μmol/L BA, 1.09 vs. Dex, 2.76, t  = 35.12; cleaved caspase-3/caspase-3: Dex + 50.0 μmol/L BA, 0.38 vs . Dex, 0.73, t  = 10.62; SHH: Dex + 50.0 μmol/L BA, 0.50 vs . Dex, 0.12, t  = 34.01; SUFU: Dex+ 50.0 μmol/L BA, 0.75 vs . Dex, 1.19, t  = 10.78; GLI-1: Dex+ 50.0 μmol/L BA, 0.40 vs . Dex, 0.11, t  = 30.68. All P  < 0.05).

CONCLUSIONS

BA antagonizes Dex-induced apoptosis of human BMSCs by activating the HH signaling pathway. It is a potential candidate for preventing SONFH.

Advances in experimental models of osteonecrosis of the femoral head

Background

Osteonecrosis of the femoral head (ONFH) is a devastating disease affecting young adults, resulting in significant pain, articular surface collapse, and disabling dysfunction. ONFH can be divided into two broad categories: traumatic and non-traumatic. It has been established that ONFH results from an inadequate blood supply that causes the death of osteocytes and bone marrow cells. Nonetheless, the precise mechanism of ONFH remains to be elucidated. In this regard, preclinical animal and cell models to study ONFH have been established to assess the efficacy of various modalities for preventing and treating ONFH. Nevertheless, it should be borne in mind that many models do not share the same physiologic and metabolic characteristics as humans. Therefore, it is necessary to establish a reproducible model that better mimics human disease.

Methods

We systematically reviewed the literatures in regard to ONFH experimental models over the past 30 years. The search was performed in PubMed and Web of Science. Original animal, cell studies with available full-text were included. This review summarizes different methods for developing animal and cell experimental models of ONFH. The advantages, disadvantages and success rates of ONFH models are also discussed. Finally, we provide experimental ONFH model schemes as a reference.

Results

According to the recent literatures, animal models of ONFH include traumatic, non-traumatic and traumatic combined with non-traumatic models. Most researchers prefer to use small animals to establish non-traumatic ONFH models. Indeed, small animal-based non-traumatic ONFH modeling can more easily meet ethical requirements with large samples. Otherwise, gradient concentration or a particular concentration of steroids to induce MSCs or EPCs, through which researchers can develop cell models to study ONFH.

Conclusions

Glucocorticoids in combination with LPS to induce ONFH animal models, which can guarantee a success rate of more than 60% in large samples. Traumatic vascular deprivation combines with non-traumatic steroids to induce ONFH, obtaining success rates ranging from 80% to 100%. However, animals that undergo vascular deprivation surgery may not survive the glucocorticoid induction process. As for cell models, 10-6mol/L Dexamethasone (Dex) to treat bone marrow stem cells, which is optimal for establishing cell models to study ONFH.

The translational potential of this article

This review aims to summarize recent development in experimental models of ONFH and recommended the modeling schemes to verify new models, mechanisms, drugs, surgeries, and biomaterials of ONFH to contribute to the prevention and treatment of ONFH.

Long Non-coding RNAs and CRISPR-Cas Edition in Tumorigenesis

Long non-coding RNAs (lncRNAs) are one of the most abundant and heterogeneous transcripts with key roles in chromatin remodeling and gene regulation at the transcriptional and post-transcriptional levels. Due to their role in cell growth and differentiation, lncRNAs have emerged as an important biomarker in cancer diagnosis, prognosis, and targeted treatment. Recent studies have focused on elucidating lncRNA function during malignant transformation, tumor progression and drug resistance. The advent of the CRISPR system has made it possible to precisely edit complex genomic loci such as lncRNAs. Thus, we summarized the advances in CRISPR-Cas approaches for functional studies of lncRNAs including gene knockout, knockdown, overexpression and RNA targeting in tumorigenesis and drug resistance. Additionally, we highlighted the perspectives and potential applications of CRISPR approaches to treat cancer, as an emerging and promising target therapy.

Mechanical Force Modulates Alveolar Bone Marrow Mesenchymal Cells Characteristics for Bone Remodeling during Orthodontic Tooth Movement through Lactate Production

Orthodontic tooth movement (OTM) relies on mechanical force-induced bone remodeling. As a metabolic intermediate of glycolysis, lactate has recently been discovered to participate in bone remodeling by serving as a signaling molecule. However, whether lactate could respond to mechanical stimulus during OTM, as well as whether lactate has an impact on the alveolar bone remodeling during orthodontics, remain to be further elucidated. In the current study, we observed physiologically elevated production of lactate along with increased osteogenic differentiation, proliferation, and migration of alveolar bone marrow mesenchymal cells (ABMMCs) under mechanical force. Inhibition of lactate, induced by cyclic mechanical stretch by GNE-140, remarkably suppressed the osteogenic differentiation, proliferation, and migration, yet enhanced apoptosis of ABMMCs. Mechanistically, these regulatory effects of lactate were mediated by histone lactylation. Taken together, our results suggest that force-induced lactate is involved in controlling bone remodeling-related cellular activities in ABMMCs and plays a vital role in the alveolar bone remodeling during OTM. Our findings indicate that lactate might be a critical modulator for alveolar bone remodeling during OTM, providing a novel therapeutic target for the purpose of more effectively controlling tooth movement and improving the stability of orthodontic results.

Dexamethasone attenuates dry eye-induced pyroptosis by regulating the KCNQ1OT1/miR-214 cascade

Dry eye disease (DED) is an inflammatory disorder of the ocular surface seriously affecting the quality of life of patients. Topical dexamethasone (Dex) administration protects the cornea from the hyperosmotic stress (HS) induced by tears. Pyroptosis participates in the activation of epithelial inflammation during DED. However, it remains unclear whether Dex attenuates the progression of DED through pyroptosis. In this study, we aimed to investigate the effect of Dex on DED using both cell and animal models and its underlying mechanism. The inflammatory factors contained in tears were detected using a cytokine assay. The pyroptosis in DED mice and human corneal epithelial cells (HCECs) treated with hyperosmotic medium under various treatments was evaluated by immunohistochemical assays (IHC) or western blotting (WB). RNA expression was manipulated with siRNA or agomir microRNAs and measured using a polymerase chain reaction. The scratch assay was used to assess the migration rate of HCECs. Remaining corneal defects were evaluated using fluorescein staining and photographed using a digital camera. Dex could suppress the release of inflammatory factors and notably attenuate pyroptosis, KCNQ1OT1 expression, and NF-κB activation induced by HS injury in vivo and in vitro. KCNQ1OT1 upregulation could activate pyroptosis by sponging miR-214. Furthermore, KCNQ1OT1 knockdown and miR-214 overexpression reversed the effect of HS, promoted the migration of HCECs, and accelerated corneal wound healing. Dex effectively suppressed HS-induced pyroptosis through the KCNQ1OT1/miR-214/caspase-1 signaling axis by inhibiting the NF-κB activation. Our results provide a novel understanding of the mechanism of Dex as an anti-inflammatory drug in DED.

LINC00473-modified bone marrow mesenchymal stem cells incorporated thermosensitive PLGA hydrogel transplantation for steroid-induced osteonecrosis of femoral head: A detailed mechanistic study and validity evaluation

The pathogenesis of steroid-induced osteonecrosis of the femoral head (SONFH) involves a glucocorticoid-induced imbalance of osteogenic and adipogenic differentiation, and apoptosis of bone marrow mesenchymal stem cells (BMSCs). An increasing number of genes, especially noncoding RNAs, have been implicated in the function of BMSCs. Our previous studies have confirmed the key role of LINC00473 and miR-23a-3p on the osteogenic, adipogenic differentiation, and apoptosis of BMSCs. However, the underlying mechanism of this process is still unclear. Based on bioinformatics analysis, here we investigated the effects of LINC00473 on the LRP5/Wnt/β-catenin signaling pathway in the osteogenesis and adipogenesis of BMSCs, as well as the PEBP1/Akt/Bad/Bcl-2 signaling pathway in dexamethasone- (Dex-) induced apoptosis of BMSCs. Our data showed that LINC00473 could promote osteogenesis and suppress the adipogenesis of BMSCs through the activation of the miR-23a-3p/LRP5/Wnt/β-catenin signaling pathway axis, while rescuing BMSCs from Dex-induced apoptosis by activating the miR-23a-3p/PEBP1/Akt/Bad/Bcl-2 signaling pathway axis. Notably, we observed that LINC00473 interacted with miR-23a-3p in an Argonaute 2 (AGO2)-dependent manner based on dual-luciferase reporter assay, AGO2-related RNA immunoprecipitation, and RNA antisense purification assay. Furthermore, injectable thermosensitive polylactic-co-glycolic acid (PLGA) hydrogel loaded with rat-derived BMSCs (rBMSCs) modified by LINC00473 were used for the treatment of SONFH in a rat model. Our results demonstrated that PLGA hydrogels provided a suitable environment for harboring rBMSCs. Besides, transplantation of PLGA hydrogels loaded with rBMSCs modified by LINC00473 could significantly promote the bone repair and reconstruction of the necrotic area at the femoral head in our SONFH rat model. Surprisingly, compared with the transplantation of BMSCs alone, the transplanted rBMSCs encapsulated within the PLGA hydrogel could migrate from the medullary cavity to the femoral head. In summary, LINC00473 promoted osteogenesis, inhibited adipogenesis, and antagonized Dex-induced apoptosis of BMSCs. Therefore, LINC00473 could provide a new strategy for the treatment of SONFH.

Role of AUF1 in modulating the proliferation, migration and senescence of skin cells

AU-rich element RNA-binding factor 1 (AUF1) is a classical RNA-binding protein. AUF1 influences the process of development, apoptosis and tumorigenesis by interacting with adenylate-uridylate rich element-bearing mRNAs. Human skin is the largest organ of the body and acts as a protective barrier against pathogens and injuries. The aim of the present study was to explore the function and potential molecular pathways of AUF1 in human skin cells. AUF1 was overexpressed in human keratinocyte HaCaT cells and human skin fibroblast WS1 cells using adenoviruses and silenced using lentiviruses. AUF1 overexpression facilitated cell proliferation, whereas AUF1 knockdown induced the opposite effect. AUF1 reduced apoptosis but did not affect cell cycle progression. Forced AUF1 expression promoted the migration of human skin cells, as demonstrated by a scratch wound healing assay. Cell senescence was alleviated in AUF1-overexpressing skin cells, while AUF1 knockdown increased cell senescence. WS1 cells with AUF1 overexpression and silencing were used for RNA-sequencing and Kyoto Encyclopedia of Genes and Genomes-based pathway analysis to identify AUF1-affected mRNAs. A total of 18 mRNAs (eight mRNAs with positive associations and 10 mRNAs with negative associations) revealed consistent associations with both AUF1 overexpression and silencing. Enriched pathways associated with AUF1 expression included 'MAPK', 'cell adhesion molecules', 'proteasome', 'cellular senescence' and 'TGF-β signaling', indicating a complex regulatory network. Overall, the results of the present study revealed that AUF1 is involved in the proliferation, migration and senescence of skin cells in vitro and may be a potential target for cosmetic and disease treatment of skin.

Astragalus polysaccharide ameliorates steroid-induced osteonecrosis of femoral head through miR-206/HIF-1α/BNIP3 axis

Declining autophagy and rising apoptosis are the main factors driving the development of steroid-induced osteonecrosis of the femoral head (SONFH). Here, we showed that astragalus polysaccharide (APS) improved femoral head necrosis via regulation of cell autophagy and apoptosis through microRNA (miR)-206/hypoxia inducible factor-1 (HIF-1α)/BCL2 interacting protein 3 (BNIP3) axis. The expression of miR-206, HIF-1α, and BNIP3 in SONFH specimens and cell model were measured using qPCR. SONFH cell model was treated with APS. Cell autophagy was evaluated using LC3-immunofluorescence assays. Flow cytometry was conducted to assess cell apoptosis. Apoptosis-related proteins and autophagy-related proteins were determined using western blot. Besides, dual-luciferase reporter assay was employed to investigate the relationship between miR-206 and HIF-1α. Here we showed that miR-206 expression was upregulated in SONFH tissues and cell model. APS promoted autophagy and inhibited apoptosis in SONFH cell model via downregulating miR-206. What is more, HIF-1α was the target of miR-206. Knockdown of HIF-1α reversed the recovery effect of miR-206 inhibitor on SONFH cell model. Furthermore, BNIP3 was the target of HIF-1α. HIF-1α overexpression promoted autophagy and inhibited apoptosis, and knockdown of BNIP3 abolished the recovery effect of HIF-1α overexpression in SONFH cell model. These results provided evidence that APS reduced miR-206 expression, and the downregulated miR-206 increased BNIP3 expression by targeting HIF-1α to promote autophagy and inhibit bone cell apoptosis. Our research proved that APS effectively improved SONFH by regulating cell autophagy and apoptosis.

Inhibition of MAGL activates the Keap1/Nrf2 pathway to attenuate glucocorticoid-induced osteonecrosis of the femoral head

Glucocorticoids (GCs) are used in treating viral infections, acute spinal cord injury, autoimmune diseases, and shock. Several patients develop GC-induced osteonecrosis of the femoral head (ONFH). However, the pathogenic mechanisms underlying GC-induced ONFH remain poorly understood. GC-directed bone marrow mesenchymal stem cells (BMSCs) fate is an important factor that determines GC-induced ONFH. At high concentrations, GCs induce BMSC apoptosis by promoting oxidative stress. In the present study, we aimed to elucidate the molecular mechanisms that relieve GC-induced oxidative stress in BMSCs, which would be vital for treating ONFH. The endocannabinoid system regulates oxidative stress in multiple organs. Here, we found that monoacylglycerol lipase (MAGL), a key molecule in the endocannabinoid system, was significantly upregulated during GC treatment in osteoblasts both in vitro and in vivo. MAGL expression was positively correlated with expression of the NADPH oxidase family and apoptosis-related proteins. Functional analysis showed that MAGL inhibition markedly reduced oxidative stress and partially rescued BMSC apoptosis. Additionally, in vivo studies indicated that MAGL inhibition effectively attenuated GC-induced ONFH. Pathway analysis showed that MAGL inhibition regulated oxidative stress in BMSCs via the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. The expression of Nrf2, a major regulator of intracellular antioxidants, was upregulated by inhibiting MAGL. Nrf2 activation can mimic the effect of MAGL inhibition and significantly reduce GC-induced oxidative damage in BMSCs. The beneficial effects of MAGL inhibition were attenuated after the blockade of the Keap1/Nrf2 antioxidant signaling pathway. Notably, pharmacological blockade of MAGL conferred femoral head protection in GC-induced ONFH, even after oxidative stress responses were initiated. Therefore, MAGL may represent a novel target for the prevention and treatment of GC-induced ONFH.

LncRNA NORAD promotes bone marrow stem cell differentiation and proliferation by targeting miR-26a-5p in steroid-induced osteonecrosis of the femoral head

BACKGROUND

Steroid-induced osteonecrosis of the femoral head (SONFH) is a devastating orthopedic disease, which seriously affects the quality of life of patients. The study aims to investigate the effects of LncRNA NORAD on SONFH.

METHODS

Human bone marrow-derived mesenchymal stem cells (hBMSCs) were isolated from the proximal femur of patients during routine orthopedic surgery and then cultured with dexamethasone (Dex) and transfected with NORAD overexpression vector, siRNA-NORAD and miR-26a-5p mimics. The mRNA expression of NORAD, miR-26a-5p, OPG, RANK, and RANKL was detected by RT-qPCR. Cell proliferation and apoptosis was measured by CCK-8 assay and flow cytometry, respectively. The protein expression of RUNX2, OPG, RANK, and RANKL was detected by western blot. The dual-luciferase reporter gene assay was performed to confirm the binding between NORAD and miR-26a-5p.

RESULTS

NORAD expression was downregulated in SONFH tissues, while miR-26a-5p expression was upregulated. Overexpression of NORAD improved DEX-induced inhibition of proliferation and differentiation, and promotion of apoptosis in hBMSCs, while knockdown of NORAD led to the opposite results. Moreover, NORAD improved DEX-induced inhibition of proliferation and differentiation, and promotion of apoptosis by regulation of miR-26a-5p in hBMSCs.

CONCLUSIONS

NORAD expression was downregulated in SONFH tissues, while miR-26a-5p expression was upregulated. NORAD improved DEX-induced inhibition of proliferation and differentiation, and promotion of apoptosis by regulation of miR-26a-5p in hBMSCs.

Differential expression profiles of long noncoding RNAs and mRNAs in human bone marrow mesenchymal stem cells after exposure to a high dosage of dexamethasone

Background

Abnormalities in apoptosis, cell cycle, proliferation, and differentiation of human bone marrow mesenchymal stem cells (hBMSCs) significantly impact bone metabolism and remodeling, resulting in various skeletal disorders. Long-term exposure to a high dosage of dexamethasone (Dex) induces apoptosis and inhibits the proliferation of mesenchymal stromal cells (MSCs), which are probable primary causes of various skeletal disorders. However, to date, the exact mechanisms of action of Dex on hBMSCs have not been fully elucidated.

Methods

To explore the effects of Dex on apoptosis, cell cycle, proliferation, senescence, osteogenic and adipogenic differentiation of hBMSCs at the various exposure times and concentrations, Hoechst 33342/PI staining, flow cytometry, crystal violet assay, β-galactosidase (β-GAL) activity assay, alizarin red S (ARS) staining assay, and Oil Red O (ORO) staining assay were performed. A microarray assay was used to identify differentially expressed lncRNAs and mRNAs in 10^− 6 mol/L Dex-treated hBMSCs, and a bioinformatics analysis was conducted to further explore the role of these differentially expressed lncRNAs and mRNAs in the coding and noncoding (CNC) network. Furthermore, the microarray results were validated using quantitative real-time PCR (qRT-PCR) analysis.

Results

Over the range of 10⁻⁸, 10⁻⁷, and 10⁻⁶ mol/L, Dex induced apoptosis, arrest of the cell cycle, inhibition of osteogenic differentiation, and promotion adipogenic differentiation of the hBMSCs in a dose-dependent manner. In addition, 10⁻⁶ mol/L Dex significantly induced apoptosis, suppressed proliferation, and increased the senescence of hBMSCs in a time-dependent manner. Interestingly, this time-dependent effect of Dex on the apoptosis of hBMSCs plateaued at the 7th day and decreased from the 8th day to the 10th day, while Dex treatment increased senescence of the hBMSCs on the 6th day. Furthermore, the microarray analysis identified a total of 137 differentially expressed mRNAs (90 upregulated and 47 downregulated) and 90 differentially expressed lncRNAs (61 upregulated and 29 downregulated) in hBMSCs after exposure to 10⁻⁶ mol/L Dex. The differentially expressed mRNAs and lncRNAs were associated with the regulation of cell apoptosis, proliferation, and cell cycle. Meanwhile, several signaling pathways involved in these processes, including the mTOR signaling pathway, Ras signaling pathway, HIF-1 signaling pathway, NF-kappa B signaling pathway, and TGF-beta signaling pathway, also were identified through the interaction net in the significant pathways (Path-Net) analysis. Furthermore, the CNC network further identified 78 core regulatory genes involved in the regulation of apoptosis. Additionally, qRT-PCR was used to confirm the identity of the key differentially expressed mRNAs and lncRNAs found to be closely associated with cell apoptosis to confirm the reliability of the microarray dataset.

Conclusions

In summary, the effect of Dex on apoptosis, cell cycle, proliferation, and osteogenic differentiation and adipogenic differentiation of the hBMSCs depended on exposure time and concentration. Continuous exposure to 10⁻⁶ mol/L of Dex for 7 days may be a suitable protocol for inducing the apoptosis of hBMSCs. Under this protocol, differentially expressed lncRNAs and mRNAs associated with apoptosis, cell cycle, and proliferation were identified, providing a new research direction for further studies.

Supplementary information

The online version contains supplementary material available at 10.1186/s13287-020-02040-8.