SYNJ2BP Improves the Production of Lentiviral Envelope Protein by Facilitating the Formation of Mitochondrion-Associated Endoplasmic Reticulum Membrane.

Equine infectious anemia virus (EIAV) and HIV are both members of the Lentivirus genus and are similar in major virological characters. EIAV endangers the horse industry. In addition, EIAV can also be used as a model for HIV research. The maturation of the lentiviral Env protein, which is necessary for viral entry, requires Env to be folded in the endoplasmic reticulum (ER). It is currently unclear how this process is regulated. Mitochondrion-associated endoplasmic reticulum membrane (MAM) is a specialized part of the close connection between the ER and mitochondria, and one of the main functions of MAM is to promote oxidative protein production in the ER. SYNJ2BP is one of the key proteins that make up the MAM, and we found that SYNJ2BP is essential for EIAV replication. We therefore constructed a SYNJ2BP knockout HEK293T cell line in which the number of MAMs is significantly reduced. Moreover, overexpression of SYNJ2BP could increase the number of MAMs. Our study demonstrates that SYNJ2BP can improve the infectivity of the EIAV virus with elevated production of the viral Env protein through increased MAM formation. Interestingly, SYNJ2BP was able to improve the production of not only EIAV Env but also HIV. Further investigation showed that MAMs can provide more ATP and calcium ions, which are essential factors for Env production, to the ER and can also reduce ER stress induced by HIV or EIAV Envs to increase the Env production level in cells. These results may help us to understand the key production mechanisms of lentiviral Env. IMPORTANCE Lentiviral Env proteins, which are rich in disulfide bonds, need to be fully folded in the ER; otherwise, misfolded Env proteins will induce ER stress and be degraded by ER-associated protein degradation (ERAD). To date, it is still unclear about Env production mechanism in the ER. MAM is the structure of closely connection between the ER and mitochondria. MAMs play important roles in the calcium steady state and oxidative stress, especially in the production of oxidative protein. For the first time, we found that SYNJ2BP can promote the production of lentiviral Env proteins by providing the ATP and calcium ions required for oxidative protein production in the ER and by reducing ER stress through facilitating formation of MAMs. These studies shed light on how MAMs improve lentiviral Env production, which will lay the foundation for the study of replication mechanisms in other lentiviruses from the perspective of the cellular organelle microenvironment.

Friend or Foe? Essential Roles of Osteoclast in Maintaining Skeletal Health.

Heightened activity of osteoclast is considered to be the culprit in breaking the balance during bone remodeling in pathological conditions, such as osteoporosis. As a "foe" of skeletal health, many antiosteoporosis therapies aim to inhibit osteoclastogenesis. However, bone remodeling is a dynamic process that requires the subtle coordination of osteoclasts and osteoblasts. Severe suppression of osteoclast differentiation will impair bone formation because of the coupling effect. Thus, understanding the complex roles of osteoclast in maintaining proper bone remodeling is highly warranted to develop better management of osteoporosis. This review aimed to determine the varied roles of osteoclasts in maintaining skeletal health and to highlight the positive roles of osteoclasts in maintaining normal bone remodeling. Generally, osteoclasts interact with osteocytes to initiate targeted bone remodeling and have crosstalk with mesenchymal stem cells and osteoblasts via secreted factors or cell-cell contact to promote bone formation. We believe that a better outcome of bone remodeling disorders will be achieved when proper strategies are made to coordinate osteoclasts and osteoblasts in managing such disorders.

Titanium particles induce apoptosis by promoting autophagy in macrophages via the PI3K/Akt signaling pathway.

Chronic inflammation and infection in the tissue surrounding implants after total joint replacement is closely associated with the innate immune response to surgical implants. Wear particles are known to increase apoptosis and impair the innate immunity in macrophages, which can cause immunosuppression around the implants. Excessive autophagy can induce apoptosis. However, the link between autophagy and apoptosis in macrophages during chronic inflammation and infection remains unknown. In this study, we investigated the autophagy and apoptosis induced by titanium particles in RAW264.7 macrophages, and in the interface membrane of patients with late-onset periprosthetic joint infection (PJI). We found that titanium particles stimulated autophagy and apoptosis in macrophages. Inhibition of autophagy significantly reduced titanium particle-induced apoptosis in macrophages, which may be related to the PI3K/Akt signaling pathway. The secretion of inflammatory factors, such as IL-1ß, IL-6, and TNF-α, decreased after inhibition of autophagy in titanium particle-stimulated macrophages, which may be caused by immune dysfunction due to titanium particle-induced autophagy and apoptosis in macrophages. Furthermore, our in vivo mouse calvarial model also showed that autophagy inhibitors lowered the rate of cell apoptosis. Our findings indicate that wear particle-induced apoptosis may be caused by enhanced autophagy in macrophages, which could potentially impair the local innate immunity in periprosthetic tissues and could be a risk factor for PJI. Based on these results, autophagy modulators may act as a new therapeutic option for PJI.

Circ-ITGA7 sponges miR-3187-3p to upregulate ASXL1, suppressing colorectal cancer proliferation.

Background: As a class of endogenous noncoding RNAs, some circular RNAs (circRNAs) have recently been reported to play a role in the regulation of tumorigenesis and progression in colorectal cancer (CRC). However, the mechanisms by which most these circRNAs function in CRC are still unclear. Purpose: The objective of this study was to identify the role of circRNA-ITGA7 in CRC cell proliferation. Patients and methods: Human genome-wide circRNA microarray v2 analysis was used for expression profile analysis. Target genes were predicted using online bioinformatics database, including TargetScan, miRDB, miRTarbase and miRMap. Gene overexpression and silencing cell models were built using cell transfection. qRT-PCR and Western blot were performed for gene and protein expression assessment. CCK8, colony formation and cell cycle analysis were used for proliferation testing. Annexin V-FITC analysis was performed for apoptosis detection. Results: CircRNA sequencing analysis suggested that compared to that in adjacent normal control tissue, the expression of circ-ITGA7, a novel circRNA, is decreased significantly in CRC. Gain-of-function studies further demonstrated that circ-ITGA7 suppressed proliferation of CRC cells. Based on prediction and verification, we subsequently revealed that miR-3187-3p is a circ-ITGA7-associated miRNA. Furthermore, RNA sequencing and bioinformatics analyses showed that ASXL1-5'UTR, the target of miR-3187-3p, is upregulated in circ-ITGA7-overexpressed cells and mediates the circ-ITGA7-induced suppression of proliferation. Conclusion: Circ-ITGA7 might suppress CRC proliferation by sponging miR-3187-3p and increasing ASXL1 expression. Thus, circ-ITGA7 might be a potential diagnostic biomarker and a therapeutic target for CRC.

SPHK-2 Promotes the Particle-Induced Inflammation of RAW264.7 by Maintaining Consistent Expression of TNF-α and IL-6.

Aseptic implant loosening is a devastating long-term complication of total joint arthroplasty. It is mainly initiated by the interaction of wear debris and macrophages. However, how does the chronic inflammation persist and how to stop it is poorly understood. Sphingosine kinases (SPHKs) are an essential feature of immunosuppressive M2 polarisation in macrophages and a promoter for chronic inflammation. In this study, RAW 264.7 macrophages were exposed to stimulation with titanium particles (0.1 mg/ml), and the subsequent expression of SPHKs and pro-inflammatory cytokines was evaluated. The effect of inhibitors of SPHKs (FTY720, PF543, and ABC294640) on titanium particle-challenged macrophages was analysed. As for results, the amount of sphingosine kinase (SPHK)-1 and SPHK-2 in RAW264.7 macrophages increased in the presence of titanium particles in a time-dependent manner. Two inhibitors of SPHKs (FTY720 and ABC294640) suppressed titanium particle-induced tumour necrosis factor (TNF)-α and interleukin (IL)-6 production in RAW264.7 macrophages. These findings suggest that persistent stimulation with titanium particles may lead to a consistent release of TNF-α and IL-6 via SPHK-2 activity, which may lead to aseptic implant loosening. Appropriate regulation of SPHK-2 may serve as a potential new strategy in the treatment of aseptic implant loosening.

Protein Disulfide Isomerase Silence Inhibits Inflammatory Functions of Macrophages by Suppressing Reactive Oxygen Species and NF-κB Pathway.

Macrophages play an essential role in inflammation. Protein disulfide isomerase (PDI) is central to the redox system, which is closely linked with the inflammatory function of macrophages. However, the relationship between PDI and inflammation is still unknown. In this study, we tested the effects of PDI on inflammatory responses in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). Using CRISPR/Cas9 system, we found that PDI knockout suppressed migration, M1 polarization, and secretion of tumor necrosis factor-α (TNF-α) and interluekin-6 (IL-6). The repression of these inflammatory processes was accompanied by decreased production of reactive oxygen species (ROS). PDI ablation also inactivated the phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activated the phosphorylation of NF-κB inhibitor alpha (IκBα). These findings demonstrate that PDI knockout inhibits the inflammatory function of macrophages by decreasing ROS production and inactivating NF-κB pathway.

Patellar non-eversion in primary TKA reduces the complication rate.

PURPOSE: This study was designed to evaluate the isolated benefits of patellar non-eversion in total knee arthroplasty (TKA). METHODS: This systematic review and meta-analysis was conducted following the PRISMA statement. A comprehensive search of the MEDLINE/PubMed, Cochrane Library, and Embase databases was performed in August 2014. Randomized controlled trials (RCTs) that considered the handling of the patella as the only variable were included in our review. Quality assessment of RCTs was performed according to the CONSORT statement. The meta-analysis was performed to pool the available data for some parameters. RESULTS: The searches of the MEDLINE/PubMed, Cochrane Library, and Embase databases yielded 10 RCTs, and five RCTs were selected for inclusion in the review. This results suggested that tourniquet time [mean difference (MD) = -5.69; 95% confidence interval (CI) -9.77 to -1.60], length of hospitalization (MD = 1.24; 95% CI 0.54-1.94) and the incidence of complications [odds ratio (OR) = 2.23; 95% CI 1.12-4.44] differed significantly between the eversion group and non-eversion group. No differences in postoperative pain, alignment, and the Insall-Salvati ratio were observed between the groups. CONCLUSION: The patellar non-eversion approach offers a shorter length of hospitalization and lower incidence of postoperative complications, but requires more operative time. The merits of patellar non-eversion for recovery of knee function remain controversial, and more high-quality RCTs are needed to draw clear conclusions. In general, avoidance of patellar eversion is recommended when exposing the knee joint for TKA.