The mitochondrial UPR induced by ATF5 attenuates intervertebral disc degeneration via cooperating with mitophagy.

Intervertebral disc degeneration (IVDD) is an aging disease that results in a low quality of life and heavy socioeconomic burden. The mitochondrial unfolded protein response (UPRmt) take part in various aging-related diseases. Our research intents to explore the role and underlying mechanism of UPRmt in IVDD. Nucleus pulposus (NP) cells were exposed to IL-1ß and nicotinamide riboside (NR) served as UPRmt inducer to treat NP cells. Detection of ATP, NAD + and NADH were used to determine the function of mitochondria. MRI, Safranin O-fast green and Immunohistochemical examination were used to determine the degree of IVDD in vivo. In this study, we discovered that UPRmt was increased markedly in the NP cells of human IVDD tissues than in healthy controls. In vitro, UPRmt and mitophagy levels were promoted in NP cells treated with IL-1ß. Upregulation of UPRmt by NR and Atf5 overexpression inhibited NP cell apoptosis and further improved mitophagy. Silencing of Pink1 reversed the protective effects of NR and inhibited mitophagy induced by the UPRmt. In vivo, NR might attenuate the degree of IDD by activating the UPRmt in rats. In summary, the UPRmt was involved in IVDD by regulating Pink1-induced mitophagy. Mitophagy induced by the UPRmt might be a latent treated target for IVDD.

Association of plasma high-density lipoprotein cholesterol level with risk of stress urinary incontinence in women: a retrospective study.

BACKGROUND: Studies have found that high density lipoprotein cholesterol (HDL-C) levels are linked to a variety of diseases. However, evidence for the relationship between stress urinary incontinence (SUI) and HDL-C remain limited. METHODS: 590 eligible women were enrolled. Basic characteristic, gynecological examinations and blood sampling were collected. The examination of the possible link between HDL-C and SUI was done using univariate and multivariate logistic regression. Feature importance ranking and Receiver operating characteristic (ROC) curves were performed to further evaluate the association between HDL-C and SUI in women. RESULTS: A significant association was found between HDL-C and SUI in women, revealing higher HDL-C levels were related to a lower risk of SUI (OR 0.238; 95%CI: 0.091-0.623; P < 0.01) after adjustment for potential key confounders. The AUC for the SUI predicted by the combined HDL-C was 0.845 (95%CI: 0.798-0.891, P < 0.001). The feature importance ranking revealed that vaginal delivery, HDL-C were the top two important factors. CONCLUSIONS: HDL-C levels were correlated with the development of SUI. In addition to physical and surgical treatments, HDL-C may offer the possibility of potential targeted treatment and prevention of SUI afterwards.

Tangeretin alleviates inflammation and oxidative response induced by spinal cord injury by activating the Sesn2/Keap1/Nrf2 pathway.

Spinal cord injury (SCI) is a severe disabling disease that is characterized by inflammation and oxidative reactions. Tangeretin has been shown to possess significant antioxidant and anti-inflammatory activities. The Keap1/Nrf2 pathway, downstream of the Sesn2 gene, is involved in regulating the inflammation and oxidative response. The main objective of this study was to investigate the effect of tangeretin on SCI and its possible mechanism through cell and animal models. A T9 clamp injury was used for the mouse model and the LPS-induced stimulation of BV-2 cells was used for the cell model. The improvement of motor function after SCI was assessed by open field, swimming, and footprint experiments. The morphological characteristics of mouse spinal cord tissue and the levels of INOS, Sesn2, TNF-α, Keap1, Nrf2, IL-10, and reactive oxygen species (ROS) in vivo and in vitro were measured by several methods including western blotting, qPCR, immunofluorescence, HE, and Nissl staining. In vivo data showed that tangeretin can improve motor function recovery and reduce neuron loss and injury size in mice with SCI. Simultaneously, the in vitro findings suggested that treatment of BV-2 cells with tangeretin after LPS stimulation reduced the production of inflammatory factors and ROS, and could convert BV-2 cells from the M1 to the M2 type. Furthermore, Sesn2 knockout suppressed Keap1/Nrf2, inflammatory factors, ROS levels, and the M1 to M2 transition. Tangeretin can alleviate the inflammation and oxidative response induced by SCI by activating the Sesn2/Keap1/Nrf2 pathway.

Sertoli cell survival and barrier function are regulated by miR-181c/d-Pafah1b1 axis during mammalian spermatogenesis.

Sertoli cells contribute to the formation of the blood-testis barrier (BTB), which is necessary for normal spermatogenesis. Recently, microRNAs (miRNAs) have emerged as posttranscriptional regulatory elements in BTB function during spermatogenesis. Our previous study has shown that miR-181c or miR-181d (miR-181c/d) is highly expressed in testes from boars at 60 days old compared with at 180 days old. Herein, we found that overexpression of miR-181c/d via miR-181c/d mimics in murine Sertoli cells (SCs) or through injecting miR-181c/d-overexpressing lentivirus in murine testes perturbs BTB function by altering BTB-associated protein distribution at the Sertoli cell-cell interface and F-actin organization, but this in vivo perturbation disappears approximately 6 weeks after the final treatment. We also found that miR-181c/d represses Sertoli cell proliferation and promotes its apoptosis. Moreover, miR-181c/d regulates Sertoli cell survival and barrier function by targeting platelet-activating factor acetylhydrolase 1b regulatory subunit 1 (Pafah1b1) gene. Furthermore, miR-181c/d suppresses PAFAH1B1 expression, reduces the complex of PAFAH1B1 with IQ motif-containing GTPase activating protein 1, and inhibits CDC42/PAK1/LIMK1/Cofilin pathway which is required for F-actin stabilization. In total, our results reveal the regulatory axis of miR-181c/d-Pafah1b1 in cell survival and barrier function of Sertoli cells and provide additional insights into miRNA functions in mammalian spermatogenesis.

Involvement of oxidative stress-induced annulus fibrosus cell and nucleus pulposus cell ferroptosis in intervertebral disc degeneration pathogenesis.

Ferroptosis is a necrotic form of regulated cell death that was associated with lipid peroxidation and free iron-mediated Fenton reactions. It has been reported that iron deficiency had been implicated in the pathogenesis of intervertebral disc degeneration (IVDD) by activating apoptosis. However, the role of ferroptosis in the process of IVDD has not been illuminated. Here, we demonstrate the involvement of ferroptosis in IVDD pathogenesis. Our in vitro models show the changes in protein levels of ferroptosis marker and enhanced lipid peroxidation level during oxidative stress. Safranin O staining, hematoxylin-eosin staining, and immunohistochemical were used to assess the IVDD after 8 weeks of surgical procedure in vivo. Treatment with ferrostatin-1, deferoxamine, and RSL3 demonstrate the role of ferroptosis in tert-butyl hydroperoxide (TBHP)-treated annulus fibrosus cells (AFCs) and nucleus pulposus cells (NPCs). Ferritinophagy, nuclear receptor coactivator 4 (NCOA4)-mediated ferritin selective autophagy, is originated during the process of ferroptosis in response to TBHP treatment. Knockdown and overexpression NCOA4 further prove TBHP may induce ferroptosis of AFCs and NPCs in an autophagy-dependent way. These findings support a role for oxidative stress-induced ferroptosis in the pathogenesis of IVDD.

Exosomes derived from vascular endothelial cells antagonize glucocorticoid-induced osteoporosis by inhibiting ferritinophagy with resultant limited ferroptosis of osteoblasts.

High dose and long-term steroid treatment can alter antioxidative ability and decrease the viability and function of osteoblasts, leading to osteoporosis and osteonecrosis. Ferroptosis, a new type of cell death characterized by excessive lipid peroxidation due to the downregulation of GPX4 and system Xc- , is involved in glucocorticoid-induced osteoporosis. Endothelial cell-secreted exosomes (EC-Exos) are important mediators of cell-to-cell communication and are involved in many physiological and pathological processes. However, the effect of EC-Exos on osteoblasts exposed to glucocorticoids has not been reported. Here, we explored the role of EC-Exos in glucocorticoid-induced osteoporosis. In vivo and in vitro experiments indicated that EC-Exos reversed the glucocorticoid-induced osteogenic inhibition of osteoblasts by inhibiting ferritinophagy-dependent ferroptosis.

Functional domains of Litopenaeus vannamei transglutaminase and their involvement in immunoregulation in shrimp.

Shrimps, which mainly rely on their innate immune system to response to infectious pathogens, have clottable proteins as an important component of this system. While transglutaminases (TGase) are found in Litopenaeus vannamei and constitute part of the coagulation system, the specific immune-related roles played by its functional domains in the immunoregulation of shrimp has not been well understood. In the present study, we report that the Ig-like domain of L. vannamei transglutaminase (TGase-C) is the main immune-related domain among the three functional domains, as it had higher bacterial agglutinative activity against Vibrio parahaemolyticus and Streptococcus iniae. Using Co-immunoprecipitation and LC-MS/MS analysis, TGase-C was shown to interact with 474 proteins, of which 52 proteins were annotated to L. vannamei. More than half of the L. vannamei annotated proteins have immune-related functions, including apoptosis. Further analysis using pull-down assay revealed that TGase-C interacted with CAP-3 (a homologue of caspase 3). In addition, siRNA-mediated knockdown of LvTGase significantly (p < 0.01) increased the expression level of LvCAP-3 coupled with a significant (p < 0.01) increase in caspase 3/7 activity, suggesting that probably LvTGase participates in shrimp immune response by modulating the activity of LvCAP-3. These findings thus suggest the Ig-like functional domain of L. vannamei's transglutaminase is the domain that is involved in immunoregulation in shrimp.

Neuropeptide Y1 Receptor Regulates Glucocorticoid-Induced Inhibition of Osteoblast Differentiation in Murine MC3T3-E1 Cells via ERK Signaling.

High dose glucocorticoid (GC) administration impairs the viability and function of osteoblasts, thus causing osteoporosis and osteonecrosis. Neuropeptide Y1 receptor (Y1 receptor) is expressed in bone tissues and cells, and regulates bone remodeling. However, the role of Y1 receptor in glucocorticoid-induced inhibition of osteoblast differentiation remains unknown. In the present study, osteoblastic cell line MC3T3-E1 cultured in osteogenic differentiation medium was treated with or without of 10-7 M dexamethasone (Dex), Y1 receptor shRNA interference, Y1 receptor agonist [Leu31, Pro34]-NPY, and antagonist BIBP3226. Cell proliferation and apoptosis were assessed by cell counting kit-8 (CCK-8) assay and cleaved caspase expression, respectively. Osteoblast differentiation was evaluated by Alizarin Red S staining and osteogenic marker gene expressions. Protein expression was detected by Western blot analysis. Dex upregulated the expression of Y1 receptor in MC3T3-E1 cells associated with reduced osteogenic gene expressions and mineralization. Blockade of Y1 receptor by shRNA transfection and BIBP3226 significantly attenuated the inhibitory effects of Dex on osteoblastic activity. Y1 receptor signaling modulated the activation of extracellular signal-regulated kinases (ERK) as well as the expressions of osteogenic genes. Y1 receptor agonist inhibited ERK phosphorylation and osteoblast differentiation, while Y1 receptor blockade exhibited the opposite effects. Activation of ERK signaling by constitutive active mutant of MEK1 (caMEK) abolished Y1 receptor-mediated Dex inhibition of osteoblast differentiation in MC3T3-E1 cells. Taken together, Y1 receptor regulates Dex-induced inhibition of osteoblast differentiation in murine MC3T3-E1 cells via ERK signaling. This study provides a novel role of Y1 receptor in the process of GC-induced suppression in osteoblast survival and differentiation.

Neutropenia and invasive fungal infection in patients with hematological malignancies treated with chemotherapy: a multicenter, prospective, non-interventional study in China.

In this study, we explored the relationship between neutropenia (absolute neutrophil count (ANC) <1,500/mm(3)) and invasive fungal infection (IFI) in Chinese patients who had hematological malignancies treated with chemotherapy. We conducted a multicenter, prospective, non-interventional study of consecutive patients with hematological malignancies undergoing chemotherapy in China and determined clinical characteristics of patients who developed neutropenia and IFI. The results indicated that for the 2,177 neutropenic patients, 88 (4.0 %) were diagnosed with IFI. We found that a high risk of IFI (P<0.05) is associated with male gender, non-remission of the primary disease, use of two or more broad-spectrum antibiotics, treatment with parenteral nutrition, presence of cardiovascular disease, history of IFI, and neutropenia. When the ANC was less than 1,000, 1,000∼500, 500∼100, and <100/mm(3), the incidence of IFI was 0.5, 5.2, 3.9, and 4.7 %, respectively (ANC>1,000/mm(3) versus other groups, P<0.001). When the ANC was less than 1,000, 500, or 100/mm(3) for 10 days or more, the incidence of IFI was 3.2 versus 6.1 % (P=0.0052), 3.5 versus 7.1 % (P=0.0021), and 3.1 versus 10.0 % (P<0.001). When the ANC was less than 100/mm(3), taking antifungal prophylaxis reduced the incidence of IFI (P<0.05). The IFI-attributable mortality rate was 11.7 %. In conclusion, Chinese patients with IFI, severe and prolonged neutropenia increases the incidence of IFI. The incidence of IFI associated with neutropenia was reduced when antifungal prophylaxis was given. IFI was associated with a significantly increased high mortality rate in hematological malignancy patients with neutropenia.

Risk-factor analysis of poor graft function after allogeneic hematopoietic stem cell transplantation.

The objective of this study was to investigate the main risk factors for poor graft function (PGF) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), to allow the improvement of transplantation outcomes through preventive measures. Clinical data for 124 patients who received allo-HSCT were analyzed retrospectively. There were 83 males (66.9%) and 41 females (33.1%) with a median age of 28 years (4-60 years). The median follow-up time was 7 months (1-116 months). Factors analyzed included age, gender, disease diagnosis, source of hematopoietic stem cells, donor type, human leukocyte antigen (HLA) matching, conditioning regimen, numbers of infused mononuclear cells and CD34(+) cells, donor-recipient sex and blood-type matching, prophylactic treatment of graft-versus-host disease (GVHD), grades of GVHD, Epstein-Barr virus or cytomegalovirus (CMV) infection, post-transplantation lymphoproliferative disorders and hepatic veno-occlusive disease. Data were analyzed by univariate and multivariate conditional logistic regression analyses. Among the 124 patients who underwent allo-HSCT, 15 developed PGF (12.1%). Univariate logistic regression analysis identified age, donor-recipient blood type and CMV infection (in 30 days) as potential risk factors for PGF. Multivariate analysis of factors with P<0.1 in univariate analysis showed that age, donor-recipient blood type and CMV infection (in 30 days) were significant risk factors for PGF. Patients were divided into subgroups based on age <20, 20-30, 30-40, and >40 years. The risk of PGF increased 2.747-fold (odds ratio (OR)=2.625, 95% confidence interval: 1.411-5.347) for each increment in age level. Patients with mismatched blood type (OR=4.051) or CMV infection (OR=9.146) had an increased risk of PGF. We conclude that age, donor-recipient blood-type matching and CMV infection are major risk factors for PGF after allo-HSCT.

Selenium nanoparticles/carboxymethyl chitosan/alginate antioxidant hydrogel for treating steroid-induced osteonecrosis of the femoral head.

Oxidative stress plays a crucial role in steroid-induced osteonecrosis of the femoral head (SONFH). Although several antioxidant strategies have been investigated for treating SONFH, their antioxidant efficiencies and therapeutic effects remain unsatisfactory. Here, we developed a selenium nanoparticles/carboxymethyl chitosan/alginate (SeNPs/CMC/Alg) antioxidant hydrogel and evaluated its ability to treat SONFH. In vitro assays indicated that the SeNPs/CMC/Alg hydrogel exhibited excellent properties, such as low cytotoxicity, sustained SeNPs release, and favorable antioxidant activity. Under oxidative stress, the SeNPs/CMC/Alg hydrogel promoted reactive oxygen species (ROS) elimination and enhanced the osteogenic and proangiogenic abilities of bone marrow mesenchymal stem cells (BMSCs). After establishing a rabbit model of SONFH, the SeNPs/CMC/Alg hydrogel was transplanted into the femoral head after core decompression (CD) surgery. Radiographic and histological analyses revealed that the hydrogel treatment alleviated SONFH by eliminating ROS and promoting osteogenesis and angiogenesis compared to those in the CD and CMC/Alg groups. In vitro and in vivo studies indicated that the Wnt/ß-catenin signaling pathway was activated by the SeNPs/CMC/Alg hydrogel in both hydrogen peroxide-conditioned BMSCs and necrotic femoral heads. These findings indicate that local transplantation of the SeNPs/CMC/Alg hydrogel is beneficial for treating SONFH, as it promotes ROS elimination and activation of the Wnt/ß-catenin signaling pathway.

Sesn2 Serves as a Regulator between Mitochondrial Unfolded Protein Response and Mitophagy in Intervertebral Disc Degeneration.

Mitochondrial unfold protein response (UPRmt) can induce mitophagy to protect cell from unfold protein. However, how UPRmt induces mitophagy to protect cell is not yet clear. Herein, Sesn2 was considered to be a key molecule that communicated UPRmt and mitophagy in the intervertebral disc. Silencing of Sesn2 was able to reverse the protective effects of Nicotinamide riboside (NR) on nucleus pulposus (NP) cells and inhibit mitophagy induced by UPRmt. UPRmt upregulated Sesn2 through Eif2ak4/eIF2α/Atf4, and further induced mitophagy. Sesn2 promoted the translocation of cytosolic Parkin and Sqstm1 to the defective mitochondria respectively, thereby enhancing mitophagy. The translocation of cytosolic Sqstm1 to the defective mitochondria was dependent on Parkin. The two functional domains of Sesn2 were necessary for the interaction of Sesn2 with Parkin and Sqstm1. The cytosolic interaction of Sesn2 between Parkin and Sqstm1 was independent on Pink1 (named as PINK1 in human) but the mitochondrial translocation was dependent on Pink1. Sesn2-/- mice showed a more severe degeneration and NR did not completely alleviate the intervertebral disc degeneration (IVDD) of Sesn2-/- mice. In conclusion, UPRmt could attenuate IVDD by upregulation of Sesn2-induced mitophagy. This study will help to further reveal the mechanism of Sesn2 regulating mitophagy, and open up new ideas for the prevention and treatment of IVDD.

Analysis of Data on Fludarabine, Cyclophosphamide, and Rituximab Chemoimmunotherapy for Chronic Lymphocytic Leukemia Shows High Patient Heterogeneity and the Need for More Consideration of Individualized Treatment.

Methods: Data from single-cell RNA sequencing (RNA-seq) of CLL patients were obtained from the Gene Expression Omnibus database. The R package was utilized to analyze the data, and the relation of results was predicted via the GeneMANIA website. The information of 7 samples covered three stages: observation stage, pretreatment by CIT with rituximab, fludarabine, and cyclophosphamide (pre-CIT), and post-CIT. The differentially expressed genes (DEGs) were identified, and functional enrichment analyses were performed. B cell subpopulations and pseudotime trajectories analysis was conducted. Results: A total of 70,659 DEGs were identified. Each patient's DEGs presented their own characteristics, with low similarity. Therefore, it is difficult to identify potential hub genes. Similarly, pathway enrichment analysis showed significant tumor heterogeneity among CLL patients. Analysis of relapsed post-CIT compared to the observation stage suggested that the TP53 pathway should be taken seriously as it is closely related to treatment strategy and patient prognosis. Conclusions: Tumor heterogeneity may be a more common manifestation of CLL. Individualized treatment should be considered for CLL. TP53 abnormality and its regulatory factors should still be the focus of CLL diagnosis and treatment.

Regulation of external electric field on the high-energy polynitrogen compound 1,5-diaminotetrazole-4 N-oxide.

BACKGROUND: The external electric field (EEF) tends to have a significant impact on chemicals, especially energetic materials. METHODS: Molecular structure, electrostatic potential (ESP), electron density difference, density of states (DOS), and frontier molecular orbitals (FMOs) of 1,5-diaminotetrazole-4N-oxide (SYX-9) are calculated by density functional theory (DFT) at B3LYP/6-311G+(d, p) and M062X/def2-TZVP under external electric field. RESULTS: Calculated results reveal that EEF has definite influence on the trigger bond of SYX-9, especially in positive direction, and the shortening of the trigger bond caused by it can effectively reduce the sensitive of SYX-9. In addition, EEF has an effect on the electron density of SYX-9. The positive EEF can reduce the HOMO-LUMO gap. From the perspective of components of energy variation and the force on atoms, the factors of structural deformation are specifically investigated. The aromaticity of SYX-9 makes its structure stable under the influence of EEF, which is verified by the method of the iso-chemical shielding surface (ICSS).

Increased Expression of Prolyl Endopeptidase Induced by Oxidative Stress in Nucleus Pulposus Cells Aggravates Intervertebral Disc Degeneration.

A healthy microenvironment of the intervertebral disc tissue is characterized by hypoxia owing to its sparse vascular distribution. Oxidative stress plays a pivotal role in the pathological development of intervertebral disc degeneration (IVDD). We found that the expression of prolyl endopeptidase (PREP) increased in degenerative nucleus pulposus (NP) tissues. The purpose of this study was to determine whether PREP is involved in oxidative-stress-induced IVDD. Tertbutyl hydroperoxide can inhibit the expression of PREP by activating the PI3K/AKT signaling pathway at low concentrations in NP cells. Knockdown of PREP protected NP cells from apoptosis induced by oxidative stress, whereas overexpression of PREP exacerbated the apoptosis of NP cells. We also investigated the connection between the PI3K/AKT signaling pathway and PREP and found that the activation of the PI3K/AKT signaling pathway downregulated the expression of PREP by inhibiting p53. As a crucial transcription factor, p53 binds to the PREP promoter region and promotes its transcription. Overexpression of PREP also impairs protein secretion in the extracellular matrix of NP cells. Furthermore, the in vivo knockout of PREP could attenuate puncture-induced IVDD. These findings suggested that the downregulation of PREP might maintain the viability of NP cells and attenuate IVDD under oxidative stress.

Vascular endothelial cell-secreted exosomes facilitate osteoarthritis pathogenesis by promoting chondrocyte apoptosis.

Exosomes are major mediators of cell-to-cell communication, and are involved in many physiological and pathological processes. Recently, the roles of exosomes in osteoarthritis (OA) and their therapeutic potential have received increasing attention. Exosomes derived from vascular endothelial cells have been confirmed to participate in the occurrence and development of numerous diseases; however, their effects in OA have not been reported. Here, we demonstrated the roles of exosomes secreted by vascular endothelial cells in the development of OA. Through in vivo and in vitro experiments, we demonstrated that exosomes derived from vascular endothelial cells decreased the ability of chondrocytes to resist oxidative stress by inhibiting autophagy and p21 expression, thereby increasing the cellular ROS content and inducing apoptosis. These findings indicate that exosomes derived from vascular endothelial cells promote the progression of OA, thus, providing new ideas for the diagnosis and treatment of OA.

The m6A "reader" YTHDF1 promotes osteogenesis of bone marrow mesenchymal stem cells through translational control of ZNF839.

N6-methyladenosine (m6A) is required for differentiation of human bone marrow mesenchymal stem cells (hBMSCs). However, its intrinsic mechanisms are largely unknown. To identify the possible role of m6A binding protein YTHDF1 in hBMSCs osteogenesis in vivo, we constructed Ythdf1 KO mice and showed that depletion of Ythdf1 would result in decreased bone mass in vivo. Both deletion of Ythdf1 in mouse BMSCs and shRNA-mediated knockdown of YTHDF1 in hBMSCs prevented osteogenic differentiation of cells in vitro. Using methylated RNA immunoprecipitation (Me-RIP) sequencing and RIP-sequencing, we found that ZNF839 (a zinc finger protein) served as a target of YTHDF1. We also verified its mouse homolog, Zfp839, was translationally regulated by Ythdf1 in an m6A-dependent manner. Zfp839 potentiated BMSC osteogenesis by interacting with and further enhancing the transcription activity of Runx2. These findings should improve our understanding of the mechanism of BMSC osteogenesis regulation and provide new ideas for the prevention and treatment of osteoporosis.

Beraprost ameliorates postmenopausal osteoporosis by regulating Nedd4-induced Runx2 ubiquitination.

Bone health requires adequate bone mass, which is maintained by a critical balance between bone resorption and formation. In our study, we identified beraprost as a pivotal regulator of bone formation and resorption. The administration of beraprost promoted differentiation of mouse bone mesenchymal stem cells (M-BMSCs) through the PI3K-AKT pathway. In co-culture, osteoblasts stimulated with beraprost inhibited osteoclastogenesis in a rankl-dependent manner. Bone mass of p53 knockout mice remained stable, regardless of the administration of beraprost, indicating that p53 plays a vital role in the bone mass regulation by beraprost. Mechanistic in vitro studies showed that p53 binds to the promoter region of neuronal precursor cell-expressed developmentally downregulated 4 (Nedd4) to promote its transcription. As a ubiquitinating enzyme, Nedd4 binds to runt-related transcription factor 2 (Runx2), which results in its ubiquitination and subsequent degradation. These data indicate that the p53-Nedd4-Runx2 axis is an effective regulator of bone formation and highlight the potential of beraprost as a therapeutic drug for postmenopausal osteoporosis.

NDUFA4L2 Regulated by HIF-1α Promotes Metastasis and Epithelial-Mesenchymal Transition of Osteosarcoma Cells Through Inhibiting ROS Production.

Osteosarcoma (OS) accounts for a large proportion of the types of bone tumors that are newly diagnosed, and is a relatively common bone tumor. However, there are still no effective treatments for this affliction. One interesting avenue is related to the mitochondrial NDUFA4L2 protein, which is encoded by the nuclear gene and is known to be a critical mediator in the regulation of cell survival. Thus, in this study, we aimed to investigate the effect of NDUFA4L2 upon the metastasis and epithelial-mesenchymal transition of OS. We found that NDUFA4L2 protein expression was upregulated in hypoxic conditions. We also used 2-ME and DMOG, which are HIF-1α inhibitors and agonists, respectively, to assess the effects related to decreasing or increasing HIF-1α expression. 2-ME caused a significant decrease of NDUFA4L2 expression and DMOG had the opposite effect. It was obvious that down-regulation of NDUFA4L2 had a direct interaction with the apoptosis of OS cells. Western blotting, wound healing analyses, Transwell invasion assays, and colony formation assays all indicated and supported the conclusion that NDUFA4L2 promoted OS cell migration, invasion, proliferation, and the epithelial-mesenchymal transition. During experiments, we incidentally discovered that autophagy and the ROS inhibitor could be used to facilitate the rescuing of tumor cells whose NDUFA4L2 was knocked down. Our findings will help to further elucidate the dynamics underlying the mechanism of OS cells and have provided a novel therapeutic target for the treatment of OS.

Inhibition of Y1 Receptor Promotes Osteogenesis in Bone Marrow Stromal Cells via cAMP/PKA/CREB Pathway.

Inhibition of neuropeptide Y1 receptor stimulates osteogenesis in vitro and in vivo. However, the underlying mechanisms involved in these effects remain poorly understood. Here we identify the effects of Y1 receptor deficiency on osteogenic differentiation in human bone marrow stromal cells (BMSCs) by using genetic and pharmacological regulation, and to explore the pathways mediating these effects. In BMSCs, inhibition of Y1 receptor stimulates osteogenesis and upregulates the expression levels of the master transcriptional factor RUNX2. Mechanistically, Y1 receptor deficiency increases the levels of intracellular cAMP, which via protein kinase A (PKA) mediated pathways results in activation of phospho-CREB (p-CREB). We find RUNX2 activation induced by Y1 receptor deficiency is reversed by H-89, a PKA inhibitor. These results indicate Y1 receptor deficiency activates PKA-mediated phosphorylation of CREB, leading to activation of RUNX2 and enhances osteogenic differentiation in BMSCs. In conclusion, these data indicate that Y1 receptor deficiency promotes osteogenic differentiation by RUNX2 stimulation through cAMP/PKA/CREB pathway.