Bcl2 deficiency activates FoxO through Akt inactivation and accelerates osteoblast differentiation

The miR-184-3p promotes rice black-streaked dwarf virus infection by suppressing Ken in Laodelphax striatellus (Fallén)

BACKGROUND

MicroRNAs (miRNAs) play a key role in various biological processes by influencing the translation of target messenger RNAs (mRNAs) through post-transcriptional regulation. The miR-184-3p has been identified as an abundant conserved miRNA in insects. However, less is known about its functions in insect-plant virus interactions.

RESULTS

The function of miR-184-3p in regulation of plant viral infection in insects was investigated using a rice black-streaked dwarf virus (RBSDV) and Laodelphax striatellus (Fallén) interaction system. We found that the expression of miR-184-3p increased in L. striatellus after RBSDV infection. Injection of miR-184-3p mimics increased RBSDV accumulation, while treatment with miR-184-3p antagomirs inhibits the viral accumulation in L. striatellus. Ken, a zinc finger protein, was identified as a target of miR-184-3p. Knockdown of Ken increased the virus accumulation and promoted RBSDV transmission by L. striatellus.

CONCLUSION

This study demonstrates that RBSDV infection induces the expression of miR-184-3p in its insect vector L. striatellus. The miR-184-3p targets Ken to promote RBSDV accumulation and transmission. These findings provide a new insight into the function of the miRNAs in regulating plant viral infection in its insect vector. © 2023 Society of Chemical Industry.

Bcl2l1 Deficiency in Osteoblasts Reduces the Trabecular Bone Due to Enhanced Osteoclastogenesis Likely through Osteoblast Apoptosis

Bcl2l1 (Bcl-XL) belongs to the Bcl-2 family, Bcl2 and Bcl2-XL are major anti-apoptotic proteins, and the apoptosis of osteoblasts is a key event for bone homeostasis. As the functions of Bcl2l1 in osteoblasts and bone homeostasis remain unclear, we generated osteoblast-specific Bcl2l1-deficient (Bcl2l1fl/flCre) mice using 2.3-kb Col1a1 Cre. Trabecular bone volume and the trabecular number were lower in Bcl2l1fl/flCre mice of both sexes than in Bcl2l1fl/fl mice. In bone histomorphometric analysis, osteoclast parameters were increased in Bcl2l1fl/flCre mice, whereas osteoblast parameters and the bone formation rate were similar to those in Bcl2l1fl/fl mice. TUNEL-positive osteoblastic cells and serum TRAP5b levels were increased in Bcl2l1fl/flCre mice. The deletion of Bcl2l1 in osteoblasts induced Tnfsf11 expression, whereas the overexpression of Bcl-XL had no effect. In a co-culture of Bcl2l1-deficient primary osteoblasts and wild-type bone-marrow-derived monocyte/macrophage lineage cells, the numbers of multinucleated TRAP-positive cells and resorption pits increased. Furthermore, serum deprivation or the deletion of Bcl2l1 in primary osteoblasts increased apoptosis and ATP levels in the medium. Therefore, the reduction in trabecular bone in Bcl2l1fl/flCre mice may be due to enhanced bone resorption through osteoblast apoptosis and the release of ATP from apoptotic osteoblasts, and Bcl2l1 may inhibit bone resorption by preventing osteoblast apoptosis.

Molecular mechanism of a novel root-end filling material containing zirconium oxide on the osteogenic/odontogenic differentiation of human osteosarcoma MG-63 cells

Although the novel root-end filling material containing zirconium oxide (NRFM-Zr) which is hydroxyapatite-based may promote osteoblast differentiation, the molecular mechanism remains unclear. The aim of this study is to investigate it underlying the osteogenic/odontogenic differentiation of human osteosarcoma MG-63 cells induced by NRFM-Zr, compared with calcium silicate-based mineral trioxide aggregate (MTA), and glass ionomer cement (GIC). Firstly, three different types of root filling materials were co-cultured with MG-63 cells, and their cell toxicity, alkaline phosphatase (ALP) activity, and calcium ion concentration were evaluated. Next, gene expression profiling microarray was employed to analyze the impact of the materials on the gene expression profile of MG-63 cells. The results of cell viability revealed that NRFM-Zr group had no significant difference compared to the negative control group. After 5 and 7 days of cultivation, both the NRFM-Zr and MTA groups exhibited significantly higher ALP activity compared to the negative control (p < 0.05). Moreover, the NRFM-Zr group had the highest calcium ion concentration, while the GIC group was the lowest (p < 0.05). Gene expression profiling microarray analysis identified 2915 (NRFM-Zr), 2254 (MTA) and 392 (GIC) differentially expressed genes, respectively. GO functional and KEGG pathway analysis revealed that differentially expressed genes of NRFM-Zr, MTA and GIC participated in 8, 6 and 0 differentiation-related pathways, respectively. Comparing the molecular mechanisms of osteogenic/odontogenic differentiation induced by hydroxyapatite-based NRFM-Zr and calcium silicate-based MTA, it was found that they shared similarities in their molecular mechanisms of promoting osteogenic differentiation. NRFM-Zr primarily promotes differentiation and inhibits cell apoptosis, thereby enhancing osteogenic/odontogenic differentiation of MG-63 cells. Furthermore, the inducing efficacy of NRFM-Zr was found to be superior to MTA.

PLK1 as a cooperating partner for BCL2-mediated antiapoptotic program in leukemia

The deregulation of BCL2 family proteins plays a crucial role in leukemia development. Therefore, pharmacological inhibition of this family of proteins is becoming a prevalent treatment method. However, due to the emergence of primary and acquired resistance, efficacy is compromised in clinical or preclinical settings. We developed a drug sensitivity prediction model utilizing a deep tabular learning algorithm for the assessment of venetoclax sensitivity in T-cell acute lymphoblastic leukemia (T-ALL) patient samples. Through analysis of predicted venetoclax-sensitive and resistant samples, PLK1 was identified as a cooperating partner for the BCL2-mediated antiapoptotic program. This finding was substantiated by additional data obtained through phosphoproteomics and high-throughput kinase screening. Concurrent treatment using venetoclax with PLK1-specific inhibitors and PLK1 knockdown demonstrated a greater therapeutic effect on T-ALL cell lines, patient-derived xenografts, and engrafted mice compared with using each treatment separately. Mechanistically, the attenuation of PLK1 enhanced BCL2 inhibitor sensitivity through upregulation of BCL2L13 and PMAIP1 expression. Collectively, these findings underscore the dependency of T-ALL on PLK1 and postulate a plausible regulatory mechanism.

Pharmacological inhibition of BCL-2 with the FDA-approved drug venetoclax impairs longitudinal bone growth

Treatment-related skeletal complications are common in childhood cancer patients and survivors. Venetoclax is a BCL-2 inhibitor that has shown efficacy in hematological malignancies in adults and is being investigated in pediatric cancer clinical trials as a promising therapeutic modality. Venetoclax triggers cell death in cancer cells, but whether it exerts similar effects in normal bone cells, is unknown. Chondrogenic ATDC5 cells, E20 fetal rat metatarsal bones, and human growth plate biopsies were treated with different concentrations of venetoclax. Female NMRI nu/nu mice were treated with venetoclax or vehicle for 15 days. Mice were X-rayed at baseline and at the end of the experiment to assess longitudinal bone growth and body weight was monitored throughout the study. Histomorphometric and immunohistochemical analyses were performed to evaluate treatment effects on the growth plate cartilage. Venetoclax decreased the viability of chondrocytes and impaired the growth of ex vivo cultured metatarsals while reducing the height of the resting/proliferative zone and the hypertrophic cell size. When tested in vivo, venetoclax suppressed bone growth and reduced growth plate height. Our experimental data suggest that venetoclax directly targets growth plate chondrocytes suppressing bone growth and we, therefore, encourage careful monitoring of longitudinal bone growth if treating growing children with venetoclax.

Relationship between osteoporosis and benign paroxysmal positional vertigo based on evidence-based medicine and bioinformatics

It has been reported that osteoporosis is a possible risk factor of benign paroxysmal positional vertigo (BPPV).

PURPOSE

We analyzed the correlation between osteoporosis and BPPV and the possible mechanism by performing evidence-based medicine meta-analysis and bioinformatics analysis.

METHODS

Initially, English articles related to osteoporosis and BPPV were obtained through PubMed and EMBASE databases. Stata12.0 software was used for meta-analysis to calculate the odd ratio (OR) and 95% confidence interval (CI) of outcome indicators, and the heterogeneity was evaluated by subgroup analysis, publication bias evaluation, and sensitivity analysis. In addition, microarray datasets related to BPPV and osteoporosis were obtained from gene expression omnibus (GEO) database to screen differentially expressed genes. At last, a mouse model of osteoporosis was established by bilateral oophorectomy for validation. RT-qPCR and Western blot analysis were performed to determine expression of related factors in mouse tissues.

RESULTS

Osteoporosis was suggested as an important risk factor for BPPV through meta-analysis of these 12 articles. It was found that PPP2CA was upregulated in BPPV and low bone mineral density (BMD) samples. Moreover, PPP2CA induced dephosphorylation of BCL2, which may be involved in BPPV through regulation of BMD. Through this mechanism, silencing of PPP2CA could elevate the incidence of BPPV by promoting bone remodeling and reducing the density of otoconia around the macula.

CONCLUSIONS

PPP2CA reduces BMD expression by inducing dephosphorylation of BCL2, which may be one of the mechanisms responsible for the onset of BPPV in osteoporosis.

Regulation and Role of Transcription Factors in Osteogenesis

Bone is a dynamic tissue constantly responding to environmental changes such as nutritional and mechanical stress. Bone homeostasis in adult life is maintained through bone remodeling, a controlled and balanced process between bone-resorbing osteoclasts and bone-forming osteoblasts. Osteoblasts secrete matrix, with some being buried within the newly formed bone, and differentiate to osteocytes. During embryogenesis, bones are formed through intramembraneous or endochondral ossification. The former involves a direct differentiation of mesenchymal progenitor to osteoblasts, and the latter is through a cartilage template that is subsequently converted to bone. Advances in lineage tracing, cell sorting, and single-cell transcriptome studies have enabled new discoveries of gene regulation, and new populations of skeletal stem cells in multiple niches, including the cartilage growth plate, chondro-osseous junction, bone, and bone marrow, in embryonic development and postnatal life. Osteoblast differentiation is regulated by a master transcription factor RUNX2 and other factors such as OSX/SP7 and ATF4. Developmental and environmental cues affect the transcriptional activities of osteoblasts from lineage commitment to differentiation at multiple levels, fine-tuned with the involvement of co-factors, microRNAs, epigenetics, systemic factors, circadian rhythm, and the microenvironments. In this review, we will discuss these topics in relation to transcriptional controls in osteogenesis.

The Skeletal Effects of Tanshinones: A Review

Background: Osteoporosis results from excessive bone resorption and reduced bone formation, triggered by sex hormone deficiency, oxidative stress and inflammation. Tanshinones are a class of lipophilic phenanthrene compounds found in the roots of Salvia miltiorrhiza with antioxidant and anti-inflammatory activities, which contribute to its anti-osteoporosis effects. This systematic review aims to provide an overview of the skeletal beneficial effects of tanshinones. Methods: A systematic literature search was conducted in January 2021 using Pubmed, Scopus and Web of Science from the inception of these databases. Original studies reporting the effects of tanshinones on bone through cell cultures, animal models and human clinical trials were considered. Results: The literature search found 158 unique articles on this topic, but only 20 articles met the inclusion criteria and were included in this review. The available evidence showed that tanshinones promoted osteoblastogenesis and bone formation while reducing osteoclastogenesis and bone resorption. Conclusions: Tanshinones modulates bone remodelling by inhibiting osteoclastogenesis and osteoblast apoptosis and stimulating osteoblastogenesis. Therefore, it might complement existing strategies to prevent bone loss.

Wrong place, wrong time: Runt-related transcription factor 2/SATB2 pathway in bone development and carcinogenesis

Upregulation or aberrant expression of genes such as special AT-rich sequence-binding protein 2 (SATB2) is necessary for normal cell differentiation and tissue development and is often associated with carcinogenesis and metastatic progression. SATB2 is a critical transcription factor for biological development of various specialized cell lineages, such as osteoblasts and neurons. The dysregulation of SATB2 expression has recently been associated with various types of cancer, while the mechanisms and pathways by which it mediates tumorigenesis are not well elucidated. Runt-related transcription factor 2 (RUNX2) is a master regulator for osteogenesis, and it shares common pathways with SATB2 to regulate bone development. Interestingly, these two transcription factors co-occur in several epithelial and mesenchymal cancers and are linked by multiple cancer-related proteins and microRNAs. This review examines the interactions between RUNX2 and SATB2 in a network necessary for normal bone development and the circumstances in which the expression of RUNX2 and SATB2 in the wrong place and time leads to carcinogenesis.

Identification of potential specific biomarkers and key signaling pathways between osteogenic and adipogenic differentiation of hBMSCs for osteoporosis therapy

Background

The differentiation of bone mesenchymal stem cells (BMSCs) into adipogenesis (AD) rather than osteogenesis (OS) is an important pathological feature of osteoporosis. Illuminating the detailed mechanisms of the differentiation of BMSCs into OS and AD would contribute to the interpretation of osteoporosis pathology.

Methods

To identify the regulated mechanism in lineage commitment of the BMSCs into OS and AD in the early stages, the gene expression profiles with temporal series were downloaded to reveal the distinct fates when BMSCs adopt a committed lineage. For both OS and AD lineages, the profiles of days 2–4 were compared with day 0 to screen the differentially expressed genes (DEGs), respectively. Next, the functional enrichment analysis was utilized to find out the biological function, and protein-protein interaction network to predict the central genes. Finally, experiments were performed to verify our finding.

Results

FoxO signaling pathway with central genes like FoxO3, IL6, and CAT is the crucial mechanism of OS, while Rap1 signaling pathway of VEGFA and FGF2 enrichment is more significant for AD. Besides, PI3K-Akt signaling pathway might serve as the latent mechanism about the initiation of differentiation of BMSCs into multiple lineages.

Conclusion

Above hub genes and early-responder signaling pathways control osteogenic and adipogenic fates of BMSCs, which maybe mechanistic models clarifying the changes of bone metabolism in the clinical progress of osteoporosis. The findings provide a crucial reference for the prevention and therapy of osteoporosis.

The Senolytic Drug Navitoclax (ABT-263) Causes Trabecular Bone Loss and Impaired Osteoprogenitor Function in Aged Mice

Senescence is a cellular defense mechanism that helps cells prevent acquired damage, but chronic senescence, as in aging, can contribute to the development of age-related tissue dysfunction and disease. Previous studies clearly show that removal of senescent cells can help prevent tissue dysfunction and extend healthspan during aging. Senescence increases with age in the skeletal system, and selective depletion of senescent cells or inhibition of their senescence-associated secretory phenotype (SASP) has been reported to maintain or improve bone mass in aged mice. This suggests that promoting the selective removal of senescent cells, via the use of senolytic agents, can be beneficial in the treatment of aging-related bone loss and osteoporosis. Navitoclax (also known as ABT-263) is a chemotherapeutic drug reported to effectively clear senescent hematopoietic stem cells, muscle stem cells, and mesenchymal stromal cells in previous studies, but its in vivo effects on bone mass had not yet been reported. Therefore, the purpose of this study was to assess the effects of short-term navitoclax treatment on bone mass and osteoprogenitor function in old mice. Aged (24 month old) male and female mice were treated with navitoclax (50 mg/kg body mass daily) for 2 weeks. Surprisingly, despite decreasing senescent cell burden, navitoclax treatment decreased trabecular bone volume fraction in aged female and male mice (−60.1% females, −45.6% males), and BMSC-derived osteoblasts from the navitoclax treated mice were impaired in their ability to produce a mineralized matrix (−88% females, −83% males). Moreover, in vitro administration of navitoclax decreased BMSC colony formation and calcified matrix production by aged BMSC-derived osteoblasts, similar to effects seen with the primary BMSC from the animals treated in vivo. Navitoclax also significantly increased metrics of cytotoxicity in both male and female osteogenic cultures (+1.0 to +11.3 fold). Taken together, these results suggest a potentially harmful effect of navitoclax on skeletal-lineage cells that should be explored further to definitively assess navitoclax’s potential (or risk) as a therapeutic agent for combatting age-related musculoskeletal dysfunction and bone loss.

Dual-specificity phosphatase 6 plays a critical role in the maintenance of a cancer stem-like cell phenotype in human endometrial cancer

The prognosis of patients with high‐grade or advanced‐stage endometrial cancer remains poor. As cancer stem‐like cells (CSCs) are thought to be associated with endometrial cancers, it is essential to investigate the molecular mechanisms that regulate endometrial CSCs. Dual‐specificity phosphatase 6 (DUSP6) functions as a negative‐feedback regulator of MAPK–ERK1/2 signaling, but its role in endometrial cancer remains unknown. We investigated whether DUSP6 is involved in cancer cell stemness using endometrial cancer cell lines and specimens from endometrial cancer patients. DUSP6 induced the expression of CSC‐related genes including ALDH1, Nanog, SOX2 and Oct4A, increased the population of cells in the G0/G1 phase, and promoted sphere formation ability. DUSP6 knockdown resulted in reduced cell invasion and metastasis, whereas DUSP6 overexpression inhibited apoptosis under serum‐free conditions. Moreover, DUSP6 decreased phosphorylated ERK1/2 and increased phosphorylated Akt levels, which potentially induces CSC features. In patients with endometrial cancers, DUSP6 expression was determined using immunohistochemistry, and based on the results, the patients were dichotomized into high‐ and low‐DUSP6‐expression groups. Progression‐free survival and overall survival were significantly shorter in the high‐DUSP6‐expression group. These results suggest that DUSP6 has potential value as a biomarker of CSCs and as a target of therapies designed to eliminate CSCs in endometrial cancer.

What's new?

Although cancer stem‐like cells (CSCs) are involved in human endometrial cancers, the underlying molecular mechanisms and biomarkers for CSCs in endometrial cancers remain elusive. Here, the authors found that DUSP6 plays an important role in regulating endometrial CSC phenotypes by increasing self‐renewal ability and starvation resistance. DUSP6 expression was required for inducing invasion and metastasis and resulted in ERK1/2 dephosphorylation and Akt phosphorylation, which potentially contribute to the promotion of CSC phenotypes. As DUSP6 expression was also positively associated with worse progression‐free and overall survival, DUSP6 represents a potential biomarker for endometrial CSCs and a therapeutic target in endometrial cancers.

The Promising Role of miR-21 as a Cancer Biomarker and Its Importance in RNA-Based Therapeutics

MicroRNAs are small noncoding transcripts that posttranscriptionally regulate gene expression via base-pairing complementarity. Their role in cancer can be related to tumor suppression or oncogenic function. Moreover, they have been linked to processes recognized as hallmarks of cancer, such as apoptosis, invasion, metastasis, and proliferation. Particularly, one of the first oncomiRs found upregulated in a variety of cancers, such as gliomas, breast cancer, and colorectal cancer, was microRNA-21 (miR-21). Some of its target genes associated with cancer are PTEN (phosphatase and tensin homolog), PDCD4 (programmed cell death protein 4), RECK (reversion-inducing cysteine-rich protein with Kazal motifs), and STAT3 (signal transducer activator of transcription 3). As a result, miR-21 has been proposed as a plausible diagnostic and prognostic biomarker, as well as a therapeutic target for several types of cancer. Currently, research and clinical trials to inhibit miR-21 through anti-miR-21 oligonucleotides and ADM-21 are being conducted. As all of the evidence suggests, miR-21 is involved in carcinogenic processes; therefore, inhibiting it could have effects on more than one type of cancer. However, whether miR-21 can be used as a tissue-specific biomarker should be analyzed with caution. Consequently, the purpose of this review is to outline the available information and recent advances regarding miR-21 as a potential biomarker in the clinical setting and as a therapeutic target in cancer to highlight its importance in the era of precision medicine.

Elucidating the mechanism of action of alpha-1-antitrypsin using retinal pigment epithelium cells exposed to high glucose. Potential use in diabetic retinopathy

BACKGROUND

Alpha-1-antitrypsin is a protein involved in avoidance of different processes that are seen in diabetic retinopathy pathogenesis. These processes include apoptosis, extracellular matrix remodeling and damage of vessel walls and capillaries. Furthermore, because of its anti-inflammatory effects, alpha-1-antitrypsin has been proposed as a possible therapeutic approach for diabetic retinopathy. Our group tested alpha-1-antitrypsin in a type 1 diabetes mouse model and observed a reduction of inflammation and retinal neurodegeneration. Thus, shedding light on the mechanism of action of alpha-1-antitrypsin at molecular level may explain how it works in the diabetic retinopathy context and show its potential for use in other retinal diseases.

METHODS

In this work, we evaluated alpha-1-antitrypsin in an ARPE-19 human cell line exposed to high glucose. We explored the expression of different mediators on signaling pathways related to pro-inflammatory cytokines production, glucose metabolism, epithelial-mesenchymal transition and other proteins involved in the normal function of retinal pigment epithelium by RT-qPCR and Western Blot.

RESULTS

We obtained different expression patterns for evaluated mediators altered with high glucose exposure and corrected with the use of alpha-1-antitrypsin.

CONCLUSIONS

The expression profile obtained in vitro for the evaluated proteins and mRNA allowed us to explain our previous results obtained on mouse models and to hypothesize how alpha-1-antitrypsin hinder diabetic retinopathy progression on a complex network between different signaling pathways.

GENERAL SIGNIFICANCE

This network helps to understand the way alpha-1-antitrypsin works in diabetic retinopathy and its scope of action.

Gene Prioritization through Consensus Strategy, Enrichment Methodologies Analysis, and Networking for Osteosarcoma Pathogenesis

Osteosarcoma is the most common subtype of primary bone cancer, affecting mostly adolescents. In recent years, several studies have focused on elucidating the molecular mechanisms of this sarcoma; however, its molecular etiology has still not been determined with precision. Therefore, we applied a consensus strategy with the use of several bioinformatics tools to prioritize genes involved in its pathogenesis. Subsequently, we assessed the physical interactions of the previously selected genes and applied a communality analysis to this protein-protein interaction network. The consensus strategy prioritized a total list of 553 genes. Our enrichment analysis validates several studies that describe the signaling pathways PI3K/AKT and MAPK/ERK as pathogenic. The gene ontology described TP53 as a principal signal transducer that chiefly mediates processes associated with cell cycle and DNA damage response It is interesting to note that the communality analysis clusters several members involved in metastasis events, such as MMP2 and MMP9, and genes associated with DNA repair complexes, like ATM, ATR, CHEK1, and RAD51. In this study, we have identified well-known pathogenic genes for osteosarcoma and prioritized genes that need to be further explored.

Curculigoside Protects against Excess-Iron-Induced Bone Loss by Attenuating Akt-FoxO1-Dependent Oxidative Damage to Mice and Osteoblastic MC3T3-E1 Cells

Summary

The present investigation found that curculigoside (CUR) can prevent excess-iron-induced bone loss in mice and cells through antioxidation and inhibiting excess-iron-induced phosphorylation of the Akt-FoxO1 pathway. CUR can attenuate the decreasing of cell viability, enhance autophagy, potentiate the antioxidant effect, and reduce apoptosis in MC3T3-E1 cells treated with excess iron through regulating the expression of FoxO1 target gene.

Introduction

Oxidative stress induced by iron overload is an important factor involved in primary osteoporosis disease and iron overload-related diseases. Curculigoside (CUR), a phenolic glycoside found abundantly in Curculigo orchioides Gaertn., has been demonstrated to possess antioxidant and antiosteoporotic properties. The aim of the present study is to explore the underlying molecular mechanism of CUR on excess-iron-induced bone loss in mice and osteoblastic MC3T3-E1 cells.

Methods

An iron-overload mice model was used to study the protective effects of CUR on bone loss induced by oxidative stress. Serum bone metabolism markers and antioxidant enzymes were also measured. To explore the antioxidant mechanism of CUR, the MC3T3-E1 osteoblastic cell line was used.

Results

In vivo studies showed that BMD and microarchitectural parameters were improved after a 3-month administration of CUR. CUR improved the biochemical parameters related to bone metabolism and the expressions of Runx2, OCN, and type 1 collagen and increased the formation of bone-mineralized nodules in vitro. CUR also inhibited ROS generation and increased the activities of antioxidant enzymes both in vivo and in vitro treated with excess iron. CUR can upregulate the level of FoxO1 and Nrf2, downregulate the level of p53 and the phosphorylation level of FoxO1, improve nuclear translocation of FoxO1, probably by inhibiting the IGFR/AKT signaling pathway, then increased cell viability and autophagy, and reduced apoptosis of MC3T3-E1 cells treated with excess iron by regulating the expression of FoxO1 target genes MnSOD, Gadd45a, Bim, FasL, and Rab7.

Conclusions

These results demonstrated that CUR was able to alleviate bone loss induced by oxidative stress resulting from iron overload, suggesting its potential use for the treatment of primary osteoporosis and bone loss in iron-overload-related diseases.

The Modulatory Properties of Astragalus membranaceus Treatment on Triple-Negative Breast Cancer: An Integrated Pharmacological Method

Background: Studies have shown that the natural products of Astragalus membranaceus (AM) can effectively interfere with a variety of cancers, but their mechanism of action on breast cancer remains unclear. Triple-negative breast cancer (TNBC) is associated with a severely poor prognosis due to its invasive phenotype and lack of biomarker-driven-targeted therapies. In this study, the potential mechanism of the target composition acting on TNBC was explored by integrated pharmacological models and in vitro experiments.

Materials and Methods: Based on the Gene Expression Omnibus (GEO) database and the relational database of Traditional Chinese Medicines (TCMs), the drug and target components were initially screened to construct a common network module, and multiattribute analysis was then used to characterize the network and obtain key drug-target information. Furthermore, network topology analysis was used to characterize the betweenness and closeness of key hubs in the network. Molecular docking was used to evaluate the affinity between compounds and targets and obtain accurate combination models. Finally, in vitro experiments verified the key component targets. The cell counting kit-8 (CCK-8) assay, invasion assay, and flow cytometric analysis were used to assess cell viability, invasiveness, and apoptosis, respectively, after Astragalus polysaccharides (APS) intervention. We also performed western blot analysis of key proteins to probe the mechanisms of correlated signaling pathways.

Results: We constructed “compound-target” (339 nodes and 695 edges) and “compound-disease” (414 nodes and 6458 edges) networks using interaction data. Topology analysis and molecular docking were used as secondary screens to identify key hubs of the network. Finally, the key component APS and biomarkers PIK3CG, AKT, and BCL2 were identified. The in vitro experimental results confirmed that APS can effectively inhibit TNBC cell activity, reduce invasion, promote apoptosis, and then counteract TNBC symptoms in a dose-dependent manner, most likely by inhibiting the PIK3CG/AKT/BCL2 pathway.

Conclusion: This study provides a rational approach to discovering compounds with a polypharmacology-based therapeutic value. Our data established that APS intervenes with TNBC cell invasion, proliferation, and apoptosis via the PIK3CG/AKT/BCL2 pathway and could thus offer a promising therapeutic strategy for TNBC.

Hydrogen sulphide mitigates homocysteine-induced apoptosis and matrix remodelling in mesangial cells through Akt/FOXO1 signalling cascade

Cellular damage and accumulation of extracellular matrix (ECM) protein in the glomerulo-interstitial space are the signatures of chronic kidney disease (CKD). Hyperhomocysteinemia (HHcy), a high level of homocysteine (Hcy) is associated with CKD and further contributes to kidney damage. Despite a large number of studies, the signalling mechanism of Hcy-mediated cellular damage and ECM remodelling in kidney remains inconclusive. Hcy metabolizes to produce hydrogen sulphide (H2S), and a number of studies have shown that H2S mitigates the adverse effect of HHcy in a variety of diseases involving several signalling molecules, including forkhead box O (FOXO) protein. FOXO is a group of transcription factor that includes FOXO1, which plays important roles in cell growth and proliferation. On the other hand, a cell survival factor, Akt regulates FOXO under normal condition. However, the involvement of Akt/FOXO1 pathway in Hcy-induced mesangial cell damage remains elusive, and whether H2S plays any protective roles has yet to be clearly defined. We treated mouse mesangial cells with or without H2S donor, GYY4137 and FOXO1 inhibitor, AS1842856 in HHcy condition and determined the involvement of Akt/FOXO1 signalling cascades. Our results indicated that Hcy inactivated Akt and activated FOXO1 by dephosphorylating both the signalling molecules and induced FOXO1 nuclear translocation followed by activation of the FOXO1 transcription factor. These led to the induction of cellular apoptosis and synthesis of excessive ECM protein, in part, due to increased ROS production, loss of mitochondrial membrane potential (ΔΨm), reduction in intracellular ATP concentration, increased MMP-2, -9, -14 mRNA and protein expression, and Col I, IV and fibronectin protein expression. Interestingly, GYY4137 or AS1842856 treatment prevented these changes by modulating Akt/FOXO1 axis in HHcy. We conclude that GYY4137 and/or AS1842856 mitigates HHcy induced mesangial cell damage and ECM remodelling by regulating Akt/FOXO1 pathway.

AKT-GSK3β Signaling Pathway Regulates Mitochondrial Dysfunction-Associated OPA1 Cleavage Contributing to Osteoblast Apoptosis: Preventative Effects of Hydroxytyrosol

Oxidative stress (OS) induces osteoblast apoptosis, which plays a crucial role in the initiation and progression of osteoporosis. Although OS is closely associated with mitochondrial dysfunction, detailed mitochondrial mechanisms underlying OS-induced osteoblast apoptosis have not been thoroughly elucidated to date. In the present study, we found that mitochondrial abnormalities largely contributed to OS-induced osteoblast apoptosis, as evidenced by enhanced production of mitochondrial reactive oxygen species; considerable reduction in mitochondrial respiratory chain complex activity, mitochondrial membrane potential, and adenosine triphosphate production; abnormality in mitochondrial morphology; and alteration of mitochondrial dynamics. These mitochondrial abnormalities were primarily mediated by an imbalance in mitochondrial fusion and fission through a protein kinase B- (AKT-) glycogen synthase kinase 3β- (GSK3β-) optic atrophy 1- (OPA1-) dependent mechanism. Hydroxytyrosol (3,4-dihydroxyphenylethanol (HT)), an important compound in virgin olive oil, significantly prevented OS-induced osteoblast apoptosis. Specifically, HT inhibited OS-induced mitochondrial dysfunction by decreasing OPA1 cleavage and by increasing AKT and GSK3β phosphorylation. Together, our results indicate that the AKT-GSK3β signaling pathway regulates mitochondrial dysfunction-associated OPA1 cleavage, which may contribute to OS-induced osteoblast apoptosis. Moreover, our results suggest that HT could be an effective nutrient for preventing osteoporosis development.

Ligustilide, a major bioactive component of Angelica sinensis, promotes bone formation via the GPR30/EGFR pathway

Angelica sinensis (Oliv.) Diels is a widely-used traditional Chinese herbal medicine in treating osteoporosis. Ligustilide (LIG) is the main component of A. sinensis and is considered to be the most effective biologically active ingredient in this plant. LIG has been found to have multiple pharmacological activities, such as anti-atherosclerosis, neuroprotection, anticancer, anti-inflammatory and analgesic. However, little is known regarding its anti-osteoporotic effects. The aims of this study were to investigate any protective effect of LIG on bone formation. The results showed that LIG significantly ameliorated inhibition of bone formation in zebrafish caused by prednisolone. LIG promoted osteoblast differentiation, including that of the pre-osteoblastic cell line MC3T3-E1 and bone marrow mesenchymal stem cells. LIG greatly improved the viability of MC3T3-E1 cells exposed to H₂O₂, attenuated H₂O₂-induced apoptosis and increased the expression of Bcl-2. Furthermore, LIG treatment lead to marked activation of phosphorylated EGFR and ERK1/2. These effects could be obviously inhibited by blocking GPR30 signaling with the specific inhibitor G15. Collectively, the results reveal that GPR30 is a positive switch for LIG to increase bone formation via regulation of EGFR, and these results provide evidence for the potential of LIG to treat osteoporosis.

Bidirectional regulation of osteogenic differentiation by the FOXO subfamily of Forkhead transcription factors in mammalian MSCs

Through loss‐ and gain‐of‐function experiments in knockout and transgenic mice, Forkhead box O (FOXO) family transcription factors have been demonstrated to play essential roles in many biological processes, including cellular proliferation, apoptosis and differentiation. Osteogenic differentiation from mesenchymal stem cells (MSCs) into osteoblasts is a well‐organized process that is carefully guided and characterized by various factors, such as runt‐related transcription factor 2 (Runx2), β‐catenin, osteocalcin (OCN), alkaline phosphatase (ALP) and activating transcription factor 4 (ATF4). Accumulating evidence suggests multiple interactions among FOXO members and the differentiation regulatory factors listed above, resulting in an enhancement or inhibition of osteogenesis in different stages of osteogenic differentiation. To systematically and integrally understand the role of FOXOs in osteogenic differentiation and explain the contrary phenomena observed in vitro and in vivo, we herein summarized FOXO‐interacting differentiation regulatory genes/factors and following alterations in differentiation. The underlying mechanism was further discussed on the basis of binding types, sites, phases and the consequent downstream transcriptional alterations of interactions among FOXOs and differentiation regulatory factors. Interestingly, a bidirectional effect of FOXOs on balancing osteogenic differentiation was discovered in MSCs. Moreover, FOXO factors are reported to be activated or suppressed by several context‐dependent signalling inputs during differentiation, and the underlying molecular basis may offer new drug development targets for treatments of bone formation defect diseases.

MiR-490-3p inhibits osteogenic differentiation in thoracic ligamentum flavum cells by targeting FOXO1

Thoracic ossification of the ligamentum flavum (TOLF) is a rare heterotopic ossification of spinal ligaments, which is the major cause of thoracic spinal canal stenosis and myelopathy. In this study, the roles of miR-490-3p and forkhead box O1 (FOXO1) in osteogenesis of human thoracic ligamentum flavum cells were investigated. MiR-490-3p was found to be down-regulated during osteogenic differentiation of thoracic ligamentum flavum cells, while their overexpression inhibited osteogenic differentiation. In addition, the analysis of target prediction and dual luciferase reporter assays supported that miR-490-3p directly targeted FOXO1 and suppressed the expression of FOXO1. Moreover, FOXO1 knockdown was displayed to attenuate the effect of miR-490-3p inhibition. ChIP assays showed that miR-490-3p negatively regulated the interaction of FOXO1 and RUNX2. These findings suggest that miR-490-3p performs an inhibitory role in osteogenic differentiation of thoracic ligamentum flavum cells by potentially targeting FOXO1.

RAGE-dependent mitochondria pathway: a novel target of silibinin against apoptosis of osteoblastic cells induced by advanced glycation end products

Advanced glycation end products (AGEs) can stimulate osteoblast apoptosis and have a critical role in the pathophysiology of diabetic osteoporosis. Mitochondrial abnormalities are closely related to osteoblast dysfunction. However, it remains unclear whether mitochondrial abnormalities are involved in AGE-induced osteoblastic cell apoptosis. Silibinin, a major flavonolignan compound of silimarin, has strong antioxidant and mitochondria-protective properties. In the present study, we explored the possible mitochondrial mechanisms underlying AGE-induced apoptosis of osteoblastic cells and the effect of silibinin on osteoblastic cell apoptosis. We demonstrated that mitochondrial abnormalities largely contributed to AGE-induced apoptosis of osteoblastic cells, as evidenced by enhanced mitochondrial oxidative stress, conspicuous reduction in mitochondrial membrane potential and adenosine triphosphate production, abnormal mitochondrial morphology, and altered mitochondrial dynamics. These AGE-induced mitochondrial abnormalities were mainly mediated by the receptor of AGEs (RAGE). In addition, we found that silibinin directly downregulated the expression of RAGE and modulated RAGE-mediated mitochondrial pathways, thereby preventing AGE-induced apoptosis of osteoblastic cells. This study not only provides a new insight into the mitochondrial mechanisms underlying AGE-induced osteoblastic cell apoptosis, but also lays a foundation for the clinical use of silibinin for the prevention or treatment of diabetic osteoporosis.

New Insights into Protein Kinase B/Akt Signaling: Role of Localized Akt Activation and Compartment-Specific Target Proteins for the Cellular Radiation Response

Genetic alterations driving aberrant activation of the survival kinase Protein Kinase B (Akt) are observed with high frequency during malignant transformation and cancer progression. Oncogenic gene mutations coding for the upstream regulators or Akt, e.g., growth factor receptors, RAS and phosphatidylinositol-3-kinase (PI3K), or for one of the three Akt isoforms as well as loss of the tumor suppressor Phosphatase and Tensin Homolog on Chromosome Ten (PTEN) lead to constitutive activation of Akt. By activating Akt, these genetic alterations not only promote growth, proliferation and malignant behavior of cancer cells by phosphorylation of various downstream signaling molecules and signaling nodes but can also contribute to chemo- and radioresistance in many types of tumors. Here we review current knowledge on the mechanisms dictating Akt’s activation and target selection including the involvement of miRNAs and with focus on compartmentalization of the signaling network. Moreover, we discuss recent advances in the cross-talk with DNA damage response highlighting nuclear Akt target proteins with potential involvement in the regulation of DNA double strand break repair.

HIF-1-mediated expression of Foxo1 serves an important role in the proliferation and apoptosis of osteoblasts derived from children's iliac cancellous bone

Activation of the transcription factor hypoxia inducible factor‑1α (HIF-1α) is considered critical for the stimulation of osteogenic markers including runt‑related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and osteocalcin, which are closely associated with forkhead boxclass O1 (Foxo1) levels in osteoblasts. The present study explored the associations between HIF‑1α and Foxo1 in the regulation of cell viability, proliferation and apoptosis of osteoblasts. Osteoblasts obtained from children's iliac cancellous bone were used in the present study, which were confirmed by immunofluorescence staining for the osteoblast marker osteocalcin. The results revealed that the levels of reactive oxygen species and apoptosis were markedly increased in cells with knockdown of HIF‑1α. By contrast, these were reduced in response to overexpressed HIF‑1α. In addition, HIF‑1α overexpression significantly stimulated cell viability, which was suppressed by silencing HIF‑1α. HIF‑1α overexpression also significantly increased the transcriptional and translational levels of Foxo1. Conversely, silencing HIF‑1α markedly suppressed the expression levels of Foxo1. Furthermore, silencing HIF‑1α reduced the expression of osteogenic markers, including Runx2, ALP and osteocalcin. Runx2 and ALP expression induced by HIF1α were markedly reversed by Foxo1 small interfering (si)RNA, whereas osteocalcin was not significantly affected by Foxo1 siRNA. Therefore, the cooperation of and interactions between HIF‑1α and Foxo1 may be involved in the regulation of osteoblast markers, and serve a pivotal role in the proliferation and apoptosis of osteoblast. The HIF1α‑induced expression of Runx2 and ALP may be completely dependent on the expression levels of Foxo1, and in turn, osteocalcin may be partially dependent on Foxo1 expression.

Expression and phosphorylation of FOXO1 influences cell proliferation and apoptosis in the gastrointestinal stromal tumor cell line GIST-T1

The mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways are activated during pathogenesis of gastrointestinal stromal tumors (GISTs). Forkhead box protein O1 (FOXO1) is a transcription factor regulated by the MAPK and PI3K pathways and is associated with multiple metabolic reactions. The present study aims to investigate the association of FOXO1 with cell proliferation and apoptosis in the cell line, GIST-T1. Cell counting kit-8 assay revealed that cell growth was inhibited by the PI3K inhibitor, LY294002, and/or MAPK inhibitor, UO126. Western blotting demonstrated that the expression of p-FOXO1 and B-cell lymphoma 2 (Bcl2) were significantly reduced, whereas the expression of Bcl-2-associated X protein was significantly increased following treatment with LY294002 and/or UO126 (all P<0.05). However, no significant change was revealed in the level of total FOXO1. Flow cytometry revealed that apoptosis was significantly increased by the pathway inhibitors (P<0.05). Specifically, the proportion of cells in the G1 phase was increased whereas the proportion in the S phase was reduced. The changes of protein expression and cell apoptosis were more evident in the LY294002 + UO126 group than in either single-inhibitor group. The results indicated that FOXO1 was able to affect cell proliferation, apoptosis and the cell cycle of GISTs. The regulation of FOXO1 was part of the PI3K and MAPK signaling network, while this regulation was mostly activated by phosphorylation of FOXO1.

LncRNA DANCR involved osteolysis after total hip arthroplasty by regulating FOXO1 expression to inhibit osteoblast differentiation

Background

Aseptic loosening of artificial hip joint is a major complication affecting the long-term use of the artificial hip joint, and is the main cause of joint replacement failure. However, the mechanism of aseptic loosening of THR has not yet cleared. The aim of this study was to investigate the underlying mechanism of DANCR in osteoblast differentiation (OD).

Methods

We detected the expressions of DANCR and FOXO1 in clinical samples and mesenchymal stem cells (MSCs) by qRT-PCR and western blotting. The effects of polymethylmethacrylate (PMMA) on OD of MSCs were examined by alkaline phosphatase (ALP) activity and Alizarin Red S (ARS) staining. The expressions of OD markers were measured by qRT-PCR and western blotting. The mechanism of DANCR in OD was detected by RNA pull-down, RNA immunoprecipitation (RIP) assay and ubiquitination assays.

Results

Compared with the surrounding normal tissues, DANCR expression was up-regulated and FOXO1 expression was down-regulated in periprosthetic tissues. PMMA suppressed ALP activity, increased DANCR expression, and decreased the expressions of FOXO1, Runx2, Osterix (Ostx) and osteocalcin (OCN). ARS staining showed that PMMA inhibited the OD of MSCs. Knockdown of DANCR attenuated the inhibitory effect of PMMA on OD. Knockdown of FOXO1 could reverse the effect of si-DANC. RNA pull-down and RIP assay implicated that DANCR bound to FOXO1. Ubiquitination assay indicated that si-DANCR could repress Skp2-mediated ubiquitination of FOXO1.

Conclusion

LncRNA DANCR could inhibit OD by regulating FOXO1 expression.

Role of endoplasmic reticulum stress in disuse osteoporosis

Osteoporosis is a major skeletal disease with low bone mineral density, which leads to an increased risk of bone fracture. Salubrinal is a synthetic chemical that inhibits dephosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) in response to endoplasmic reticulum (ER) stress. To understand possible linkage of osteoporosis to ER stress, we employed an unloading mouse model and examined the effects of salubrinal in the pathogenesis of disuse osteoporosis. The results presented several lines of evidence that osteoclastogenesis in the development of osteoporosis was associated with ER stress, and salubrinal suppressed unloading-induced bone loss. Compared to the age-matched control, unloaded mice reduced the trabecular bone area/total area (B.Ar/T.Ar) as well as the number of osteoblasts, and they increased the osteoclasts number on the trabecular bone surface in a time-dependent way. Unloading-induced disuse osteoporosis significantly increased the expression of Bip, p-eIF2α and ATF4 in short-term within 6h of tail suspension, but time-dependent decreased in HU2d to HU14d. Furthermore, a significant correlation of ER stress with the differentiation of osteoblasts and osteoclasts was observed. Administration of salubrinal suppressed the unloading-induced decrease in bone mineral density, B.Ar/T.Ar and mature osteoclast formation. Salubrinal also increased the colony-forming unit-fibroblasts and colony-forming unit-osteoblasts. It reduced the formation of mature osteoclasts, suppressed their migration and adhesion, and increased the expression of Bip, p-eIF2α and ATF4. Electron microscopy showed that rough endoplasmic reticulum expansion and a decreased number of ribosomes on ER membrane were observed in osteoblast of unloading mice, and the abnormal ER expansion was significantly improved by salubrinal treatment. A TUNEL assay together with CCAAT/enhancer binding protein homologous protein (CHOP) expression indicated that ER stress-induced osteoblast apoptosis was rescued by salubrinal. Collectively, the results support the notion that ER stress plays a key role in the pathogenesis of disuse osteoporosis, and salubrinal attenuates unloading-induced bone loss by altering proliferation and differentiation of osteoblasts and osteoclasts via eIF2α signaling.

Cell Death in Chondrocytes, Osteoblasts, and Osteocytes

Cell death in skeletal component cells, including chondrocytes, osteoblasts, and osteocytes, plays roles in skeletal development, maintenance, and repair as well as in the pathogenesis of osteoarthritis and osteoporosis. Chondrocyte proliferation, differentiation, and apoptosis are important steps for endochondral ossification. Although the inactivation of P53 and RB is involved in the pathogenesis of osteosarcomas, the deletion of p53 and inactivation of Rb are insufficient to enhance chondrocyte proliferation, indicating the presence of multiple inhibitory mechanisms against sarcomagenesis in chondrocytes. The inflammatory processes induced by mechanical injury and chondrocyte death through the release of danger-associated molecular patterns (DAMPs) are involved in the pathogenesis of posttraumatic osteoarthritis. The overexpression of BCLXL increases bone volume with a normal structure and maintains bone during aging by inhibiting osteoblast apoptosis. p53 inhibits osteoblast proliferation and enhances osteoblast apoptosis, thereby reducing bone formation, but also exerts positive effects on osteoblast differentiation through the Akt–FoxOs pathway. Apoptotic osteocytes release ATP, which induces the receptor activator of nuclear factor κ-B ligand (Rankl) expression and osteoclastogenesis, from pannexin 1 channels. Osteocyte death ultimately results in necrosis; DAMPs are released to the bone surface and promote the production of proinflammatory cytokines, which induce Rankl expression, and osteoclastogenesis is further enhanced.

Cell-free DNA induced apoptosis of granulosa cells by oxidative stress

BACKGROUND

Cell-free DNA is a DNA fragment that is produced by cell apoptosis which can affect the micro-environment of cell apoptosis. The levels of Cell-free DNA have been associated with successful rate of in vitro fertilization-embryo transfer (IVF-ET) and embryonic development. Our aim is to determine the relationship between cell-free DNA and embryo quality. The mechanisms of cell-free DNA in granulose and the apoptosis will be determined also.

METHODS

The study enrolled patients who were undergone IVF for the first time and grouped the patients as pregnant (n=130) and non-pregnant (n=59). The relationship was determined by statistical analysis between the levels of cell-free DNA in the follicular fluid and clinical data of IVF patients. Flow cytometry was done to detect the rate of granulosa cell apoptosis and intracellular reactive oxygen species (ROS) level. Western blotting and fluorescent quantitative PCR detected the apoptosis-related gene expressions.

RESULTS

Clinical data statistics showed that cell-free DNA levels were positively correlated with granulosa cell apoptosis and negatively correlated with embryo quality and pregnancy rates. High levels of cell-free DNA lead to increased ROS in granulosa cells and activated caspase through Fas/FasL that induced apoptosis.

CONCLUSION

High levels of cell-free DNA triggers granulosa cell apoptosis and influences oocyte maturation embryo development and pregnancy rates in IVF treatments. Cell-free DNA can be as a secondary criteria and predictive marker for the quality control of IVF embryo.

Overexpression of BCLXL in Osteoblasts Inhibits Osteoblast Apoptosis and Increases Bone Volume and Strength

The Bcl2 family proteins, Bcl2 and BclXL, suppress apoptosis by preventing the release of caspase activators from mitochondria through the inhibition of Bax subfamily proteins. We reported that BCL2 overexpression in osteoblasts using the 2.3 kb Col1a1 promoter increased osteoblast proliferation, failed to reduce osteoblast apoptosis, inhibited osteoblast maturation, and reduced the number of osteocyte processes, leading to massive osteocyte death. We generated BCLXL (BCL2L1) transgenic mice using the same promoter to investigate BCLXL functions in bone development and maintenance. Bone mineral density in the trabecular bone of femurs was increased, whereas that in the cortical bone was similar to that in wild-type mice. Osteocyte process formation was unaffected and bone structures were similar to those in wild-type mice. A micro-CT analysis showed that trabecular bone volume in femurs and vertebrae and the cortical thickness of femurs were increased. A dynamic bone histomorphometric analysis revealed that the mineralizing surface was larger in trabecular bone, and the bone-formation rate was increased in cortical bone. Serum osteocalcin but not TRAP5b was increased, BrdU-positive osteoblastic cell numbers were increased, TUNEL-positive osteoblastic cell numbers were reduced, and osteoblast marker gene expression was enhanced in BCLXL transgenic mice. The three-point bending test indicated that femurs were stronger in BCLXL transgenic mice than in wild-type mice. The frequency of TUNEL-positive primary osteoblasts was lower in BCLXL transgenic mice than in wild-type mice during cultivation, and osteoblast differentiation was enhanced but depended on cell density, indicating that enhanced differentiation was mainly owing to reduced apoptosis. Increased trabecular and cortical bone volumes were maintained during aging in male and female mice. These results indicate that BCLXL overexpression in osteoblasts increased the trabecular and cortical bone volumes with normal structures and maintained them majorly by preventing osteoblast apoptosis, implicating BCLXL as a therapeutic target of osteoporosis. © 2016 American Society for Bone and Mineral Research.

Foxo3 activity promoted by non-coding effects of circular RNA and Foxo3 pseudogene in the inhibition of tumor growth and angiogenesis

It has recently been shown that the upregulation of a pseudogene specific to a protein-coding gene could function as a sponge to bind multiple potential targeting microRNAs (miRNAs), resulting in increased gene expression. Similarly, it was recently demonstrated that circular RNAs can function as sponges for miRNAs, and could upregulate expression of mRNAs containing an identical sequence. Furthermore, some mRNAs are now known to not only translate protein, but also function to sponge miRNA binding, facilitating gene expression. Collectively, these appear to be effective mechanisms to ensure gene expression and protein activity. Here we show that expression of a member of the forkhead family of transcription factors, Foxo3, is regulated by the Foxo3 pseudogene (Foxo3P), and Foxo3 circular RNA, both of which bind to eight miRNAs. We found that the ectopic expression of the Foxo3P, Foxo3 circular RNA and Foxo3 mRNA could all suppress tumor growth and cancer cell proliferation and survival. Our results showed that at least three mechanisms are used to ensure protein translation of Foxo3, which reflects an essential role of Foxo3 and its corresponding non-coding RNAs.

Impairment of insulin receptor substrate 1 signaling by insulin resistance inhibits neurite outgrowth and aggravates neuronal cell death

In the central nervous system (CNS), insulin resistance (I/R) can cause defective neurite outgrowth and neuronal cell death, which can eventually lead to cognitive deficits. Recent research has focused on the relationship between I/R and the cognitive impairment caused by dementia, with the goal of developing treatments for dementia. Insulin signal transduction mediated by insulin receptor substrate (IRS-1) has been thoroughly studied in the CNS of patients with I/R. In the present study, we investigated whether the impairment of IRS-1-mediated insulin signaling contributes to neurite outgrowth and neuronal loss, both in mice fed a high-fat diet and in mouse neuroblastoma (Neuro2A) cells. To investigate the changes caused by the inhibition of IRS-1-mediated insulin signaling in the brain, we performed Cresyl Violet staining and immunochemical analysis. To investigate the changes caused by the inhibition of IRS-1-mediated insulin signaling in neuroblastoma cells, we performed Western blot analysis, reverse transcription-PCR, and immunochemical analysis. We show that the deactivation of IRS-1-mediated insulin signaling can inhibit neuronal outgrowth and aggravate neuronal cell death in the insulin-resistant CNS. Thus, IRS-1-mediated insulin signal transduction may be an important factor in the treatment of cognitive decline induced by I/R.

Antioxidative fullerol promotes osteogenesis of human adipose-derived stem cells

Antioxidants were implicated as potential reagents to enhance osteogenesis, and nano-fullerenes have been demonstrated to have a great antioxidative capacity by both in vitro and in vivo experiments. In this study, we assessed the impact of a polyhydroxylated fullerene, fullerol, on the osteogenic differentiation of human adipose-derived stem cells (ADSCs). Fullerol was not toxic against human ADSCs at concentrations up to 10 μM. At a concentration of 1 μM, fullerol reduced cellular reactive oxygen species after a 5-day incubation either in the presence or in the absence of osteogenic media. Pretreatment of fullerol for 7 days increased the osteogenic potential of human ADSCs. Furthermore, when incubated together with osteogenic medium, fullerol promoted osteogenic differentiation in a dose-dependent manner. Finally, fullerol proved to promote expression of FoxO1, a major functional isoform of forkhead box O transcription factors that defend against reactive oxygen species in bone. Although further clarification of related mechanisms is required, the findings may help further development of a novel approach for bone repair, using combined treatment of nano-fullerol with ADSCs.