Nuclear autoantigenic sperm protein facilitates glioblastoma progression and radioresistance by regulating the ANXA2/STAT3 axis.

AIMS: Although radiotherapy is a core treatment modality for various human cancers, including glioblastoma multiforme (GBM), its clinical effects are often limited by radioresistance. The specific molecular mechanisms underlying radioresistance are largely unknown, and the reduction of radioresistance is an unresolved challenge in GBM research. METHODS: We analyzed and verified the expression of nuclear autoantigenic sperm protein (NASP) in gliomas and its relationship with patient prognosis. We also explored the function of NASP in GBM cell lines. We performed further mechanistic experiments to investigate the mechanisms by which NASP facilitates GBM progression and radioresistance. An intracranial mouse model was used to verify the effectiveness of combination therapy. RESULTS: NASP was highly expressed in gliomas, and its expression was negatively correlated with the prognosis of glioma. Functionally, NASP facilitated GBM cell proliferation, migration, invasion, and radioresistance. Mechanistically, NASP interacted directly with annexin A2 (ANXA2) and promoted its nuclear localization, which may have been mediated by phospho-annexin A2 (Tyr23). The NASP/ANXA2 axis was involved in DNA damage repair after radiotherapy, which explains the radioresistance of GBM cells that highly express NASP. NASP overexpression significantly activated the signal transducer and activator of transcription 3 (STAT3) signaling pathway. The combination of WP1066 (a STAT3 pathway inhibitor) and radiotherapy significantly inhibited GBM growth in vitro and in vivo. CONCLUSION: Our findings indicate that NASP may serve as a potential biomarker of GBM radioresistance and has important implications for improving clinical radiotherapy.

Neuropathologist-level integrated classification of adult-type diffuse gliomas using deep learning from whole-slide pathological images.

Current diagnosis of glioma types requires combining both histological features and molecular characteristics, which is an expensive and time-consuming procedure. Determining the tumor types directly from whole-slide images (WSIs) is of great value for glioma diagnosis. This study presents an integrated diagnosis model for automatic classification of diffuse gliomas from annotation-free standard WSIs. Our model is developed on a training cohort (n = 1362) and a validation cohort (n = 340), and tested on an internal testing cohort (n = 289) and two external cohorts (n = 305 and 328, respectively). The model can learn imaging features containing both pathological morphology and underlying biological clues to achieve the integrated diagnosis. Our model achieves high performance with area under receiver operator curve all above 0.90 in classifying major tumor types, in identifying tumor grades within type, and especially in distinguishing tumor genotypes with shared histological features. This integrated diagnosis model has the potential to be used in clinical scenarios for automated and unbiased classification of adult-type diffuse gliomas.

Artesunate alleviates psoriasis-like dermatitis by reducing interleukin-23 expression in tumor necrosis factor-alpha-induced HaCaT cells.

Artesunate (ART), an antimalarial drug with a multifunctional immunomodulatory effect, reduces psoriasis disease. ART can alleviate psoriasis-like dermatitis in mice but has no effect on proinflammatory cytokines in the blood. Thus, we hypothesized that the skin might be the target tissue of ART during the treatment of psoriasis. The interleukin (IL)-23/IL-17 axis has a key role in the pathogenesis of psoriasis. However, whether and how ART manipulates the IL-23 signal during psoriasis is unknown. This study found that IL-23 is highly expressed in the epidermis of psoriasis lesions and positively correlated with histological neutrophil infiltration and clinical psoriasis area and severity index (PASI) scores. Furthermore, ART inhibits the migration and cell cycle, as well as tumor necrosis factor-alpha (TNF-α)-induced IL-23 expression in HaCaT cells in a dose-dependent manner, probably through interference with the nuclear factor kappa B (NF-κB) signalling pathway. Animal experiments in imiquimod (IMQ)-induced psoriasis-like mice model also suggested that ART dose-dependently reduces IL-23 in the epidermis and ameliorates neutrophil infiltration. These findings thus provide further molecular evidence supporting ART as a promising drug for psoriasis in clinic.

The orexinergic system mediates the excitatory effects of caffeine on the arousal and sympathetic activity.

Objective: Caffeine is a non-selective adenosine receptor antagonist with pro-arousal and pro-sympathetic nervous system excitatory effects, and these pharmacological effects fit well with the physiological functions of orexin. The purpose of this study was to investigate the role of the orexinergic nervous system in the pharmacological effects of caffeine. Methods: An animal model of sleepiness caused by adenosine accumulation was established by sleep deprivation, and caffeine's effects on the spontaneous activity and sympathetic nervous system of the model animals were evaluated by using the open-field experiment and gastrointestinal peristaltic observation, respectively, and the intervention of orexin receptor antagonists on the pharmacological effects of caffeine was also observed. Results: Mice with 8 h of sleep deprivation showed a significant decrease in spontaneous activity and a significant increase in gastrointestinal push distance. After caffeine intervention, the spontaneous activities of sleep-deprived mice significantly increased and gastrointestinal peristalsis significantly decreased dose-dependent, while orexin receptors antagonist blocked the pro-arousal and inhibitory gastrointestinal peristalsis effects of caffeine on sleep-deprived mice. Conclusions: Orexinergic nervous system mediated caffeine's excitatory effects on the pro-arousal and pro-sympathetic nervous systems. Orexin is likely to be an important performer in the pharmacological effects of caffeine.

Improving Noninvasive Classification of Molecular Subtypes of Adult Gliomas With Diffusion-Weighted MR Imaging: An Externally Validated Machine Learning Algorithm.

BACKGROUND: Genetic testing for molecular markers of gliomas sometimes is unavailable because of time-consuming and expensive, even limited tumor specimens or nonsurgery cases. PURPOSE: To train a three-class radiomic model classifying three molecular subtypes including isocitrate dehydrogenase (IDH) mutations and 1p/19q-noncodeleted (IDHmut-noncodel), IDH wild-type (IDHwt), IDH-mutant and 1p/19q-codeleted (IDHmut-codel) of adult gliomas and investigate whether radiomic features from diffusion-weighted imaging (DWI) could bring additive value. STUDY TYPE: Retrospective. POPULATION: A total of 755 patients including 111 IDHmut-noncodel, 571 IDHwt, and 73 IDHmut-codel cases were divided into training (n = 480) and internal validation set (n = 275); 139 patients including 21 IDHmut-noncodel, 104 IDHwt, and 14 IDHmut-codel cases were utilized as external validation set. FIELD STRENGTH/SEQUENCE: A 1.5 T or 3.0 T/multiparametric MRI, including T1-weighted (T1), T1-weighted gadolinium contrast-enhanced (T1c), T2-weighted (T2), fluid attenuated inversion recovery (FLAIR), and DWI. ASSESSMENT: The performance of multiparametric radiomic model (random-forest model) using 22 selected features from T1, T2, FLAIR, T1c images and apparent diffusion coefficient (ADC) maps, and conventional radiomic model using 20 selected features from T1, T2, FLAIR, and T1c images was assessed in internal and external validation sets by comparing probability values and actual incidence. STATISTICAL TESTS: Mann-Whitney U test, Chi-Squared test, Wilcoxon test, receiver operating curve (ROC), and area under the curve (AUC); DeLong analysis. P < 0.05 was statistically significant. RESULTS: The multiparametric radiomic model achieved AUC values for IDHmut-noncodel, IDHwt, and IDHmut-codel of 0.8181, 0.8524, and 0.8502 in internal validation set and 0.7571, 0.7779, and 0.7491 in external validation set, respectively. Multiparametric radiomic model showed significantly better diagnostic performance after DeLong analysis, especially in classifying IDHwt and IDHmut-noncodel subtypes. DATA CONCLUSION: Radiomic features from DWI could bring additive value and improve the performance of conventional MRI-based radiomic model for classifying the molecular subtypes especially IDHmut-noncodel and IDHwt of adult gliomas. TECHNICAL EFFICACY: Stage 2.

Radiomic features from dynamic susceptibility contrast perfusion-weighted imaging improve the three-class prediction of molecular subtypes in patients with adult diffuse gliomas.

OBJECTIVES: To investigate whether radiomic features extracted from dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI) can improve the prediction of the molecular subtypes of adult diffuse gliomas, and to further develop and validate a multimodal radiomic model by integrating radiomic features from conventional and perfusion MRI. METHODS: We extracted 1197 radiomic features from each sequence of conventional MRI and DSC-PWI, respectively. The Boruta algorithm was used for feature selection and combination, and a three-class random forest method was applied to construct the models. We also constructed a combined model by integrating radiomic features and clinical metrics. The models' diagnostic performance for discriminating the molecular subtypes (IDH wild type [IDHwt], IDH mutant and 1p/19q-noncodeleted [IDHmut-noncodel], and IDH mutant and 1p/19q-codeleted [IDHmut-codel]) was compared using AUCs in the validation set. RESULTS: We included 272 patients (training set, n = 166; validation set, n = 106) with grade II-IV gliomas (mean age, 48.7 years; range, 19-77 years). The proportions of the molecular subtypes were 66.2% IDHwt, 15.1% IDHmut-noncodel, and 18.8% IDHmut-codel. Nineteen radiomic features (13 from conventional MRI and 6 from DSC-PWI) were selected to build the multimodal radiomic model. In the validation set, the multimodal radiomic model showed better performance than the conventional radiomic model did in predicting the IDHwt and IDHmut-codel subtypes, which was comparable to the conventional radiomic model in predicting the IDHmut-noncodel subtype. The multimodal radiomic model yielded similar performance as the combined model in predicting the three molecular subtypes. CONCLUSIONS: Adding DSC-PWI to conventional MRI can improve molecular subtype prediction in patients with diffuse gliomas. KEY POINTS: • The multimodal radiomic model outperformed conventional MRI when predicting both the IDH wild type and IDH mutant and 1p/19q-codeleted subtypes of gliomas. • The multimodal radiomic model showed comparable performance to the combined model in the prediction of the three molecular subtypes. • Radiomic features from T1-weighted gadolinium contrast-enhanced and relative cerebral blood volume images played an important role in the prediction of molecular subtypes.

CD19+CD24highCD27+ B cell and interleukin 35 as potential biomarkers of disease activity in systemic lupus erythematosus patients.

BACKGROUND: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that associates with aberrant activation of B lymphocytes and excessive autoantibodies. Interleukin 10 (IL-10)/interleukin 35 (IL-35) and IL-10/IL-35-producing regulatory B cells have been demonstrated to possess immunosuppressive functions during systemic lupus erythematosus. Here, we detected the proportion of CD19+CD24highCD27+ B cells as well as IL-10 and IL-35 levels in peripheral blood of SLE patients and healthy individuals, and investigated their relations with clinical features of SLE. METHODS: 41 SLE patients and 25 healthy controls were recruited. The patients were divided into groups based on SLEDAI score, anti-dsDNA antibody, rash, nephritis and hematological disorder. Flow cytometry was used to detect the proportion of CD24hiCD27+ B cells. ELISA was used to detect serum levels of IL-10 and IL-35. RESULTS: Our results showed that the CD19+CD24highCD27+ B population was decreased in active SLE patients, and anti-correlated with the disease activity. Of note, we found significant increase of IL-10 and decrease of IL-35 in SLE patients with disease activity score > 4, lupus nephritis or hematological disorders compared to those without related clinical features. CONCLUSIONS: Reduced CD19+CD24highCD27+ B cells expression may be involved in the pathogenesis of SLE. Moreover, we supposed that IL-35 instead of IL-10 played a crucial role in immune regulation during SLE disease.

Association of latent class analysis-derived subphenotypes of acute kidney injury with mortality in critically ill patients with cardiovascular disease: a retrospective cohort study.

BACKGROUND: To explore the potential heterogeneity of acute kidney injury (AKI) and evaluate the prognostic differences among AKI subphenotypes in critically ill patients with cardiovascular diseases. METHODS: Data were extracted from the Medical Information Mart for Intensive Care (MIMIC)-III database. Latent class analysis (LCA) was used to explore the potential subphenotypes of AKI in critically ill patients with cardiovascular diseases. The number of classes was identified by the Bayesian information criterion and entropy. The differences in prognostic ability among the AKI subphenotypes were evaluated by logistic regression analysis. RESULT: A total of 7738 AKI patients were enrolled in this study. Using LCA, AKI patients were divided into 4 heterogeneous subphenotypes, which were obviously different from the Kidney Disease: Improving Global Outcomes (KDIGO) stages. Interestingly, class 3 classified by LCA was dominated by stage 2, while the mortality rate in class 3 was significantly different from that in class 1 (15.2% vs. 1.6%, p < 0.05). After further adjustment, the mortality rate in class 3 remained higher than that in class 1, with an odds ratio of 12.31 (95% confidence interval, 8.96-16.89). CONCLUSIONS: LCA was feasible for AKI classification in critically ill patients with cardiovascular disease, and 4 distinct subphenotypes of AKI patients with different prognoses were identified. Our results highlighted the potential heterogeneity of AKI patients, which is worthy of further investigation.

Can wastewater surveillance assist China to cost-effectively prevent the nationwide outbreak of COVID-19?

China has controlled the nationwide spread of COVID-19 since April 2020, but it is still facing an enormous threat of disease resurgence originating from infected international travelers. Taking the rapid transmission and the mutation of SARS-CoV-2 into consideration, the current status would be easily jeopardized if sporadic locally-transmitted individuals are not identified at an early stage. Clinical diagnosis is the gold standard for COVID-19 surveillance, but it is hard to screen presymptomatic or asymptomatic cases in those who have not exhibited symptoms. Since presymptomatic or asymptomatic individuals are infectious, it is urgent to establish a surveillance system based on other tools that can profile the entire population. Infected people including those who are symptomatic, presymptomatic, and asymptomatic shed SARS-CoV-2 RNA in feces and thereby endow wastewater-based epidemiology (WBE) with an early-warning ability for mass COVID-19 surveillance. In the context of China's "COVID-zero" strategy, this work intends to discuss the practical feasibility of WBE applications as an early warning and disease surveillance system in hopes that WBE together with clinical testing would cost-effectively restrain sporadic COVID-19 outbreaks in China.

Effectively remove p-arsanilic acid from water over amphiphilic amino modified collagen fiber.

Efficient and rapid removal of p-arsanilic acid (p-ASA) in water is very important in environmental protection and human health, however it is still a severe challenge in actual engineering. Herein, a novel sorbent (CF-PEI) was successfully fabricated by simply modifying the amphiphilic skin collagen fiber (CF) substrate with Polyethylenimine (PEI). The as-prepared CF-PEI exhibits high-efficiency adsorption for negatively charged p-ASA with aromatic rings due to the introduction of amino groups and the existence of hydrophobic bands, and the maximum adsorption capacity of CF-PEI for p-ASA was high up to 285.71 mg g-1. In addition, the adsorption mechanism of CF-PEI on p-ASA mainly includes electrostatic interaction, hydrogen bond and amphiphilicity. The multi-level all-fiber structure of CF makes it mainly focus on surface mass transfer with short mass transfer distance, and its capillary drainage effect can realize large flow and rapid separation. CF-PEI based on CF can realize the ability to separate low-concentration p-ASA with high flow rate and high efficiency. The effective processing volume was 12.5 L g-1 when the separation flux reached as high as 9931.27 L m-2 h-1. Notably, the p-ASA adsorbed on CF-PEI was almost completely eluted by NaOH (0.5 mol L-1). The adsorbent is convenient to prepare, recyclable, high in efficiency, and has a great application prospect in removing organic micro-pollutants.

Mesenchymal Stem Cells Activate the MEK/ERK Signaling Pathway and Enhance DNA Methylation via DNMT1 in PBMC from Systemic Lupus Erythematosus.

The defective MEK/ERK signaling pathway and downstream hypomethylation pattern of lymphocytes are crucial for the pathogenesis of systemic lupus erythematosus (SLE). However, the role that the mesenchymal stem cells play in the MEK/ERK signaling pathway and DNA methylation of peripheral blood mononuclear cells (PBMC) from SLE patients remains unknown. In this study, we found that the MEK/ERK signaling pathway of PBMC from SLE patients was activated after the coculture with bone marrow-derived mesenchymal stem cells (BM-MSC) compared with that from the control group. In addition, the expression level of DNA methyltransferase 1 (DNMT1) increased while the levels of CD70, integrin, alpha L (ITGAL), selectin-l, and IL-13 were reduced in PBMC from SLE patients. However, no obvious effect of BM-MSC on PBMC from healthy controls was observed. These findings revealed that BM-MSC might downregulate the expression of methylation-sensitive genes and then suppress the autoactivated PBMC via the MEK/ERK signaling pathway. And it may be one of the mechanisms that BM-MSC ameliorated SLE.

Hand eczema among healthcare workers in Guangzhou City: a cross-sectional study.

BACKGROUND: Healthcare workers are at high risk of developing hand eczema. This study aimed to investigate the association between occupational hygiene and self-reported hand eczema among nurses and doctors in Guangzhou. METHODS: A cross-sectional study using a self-administrated questionnaire sent to 740 health care workers in two tertiary hospitals between 1st April and 1st July 2019 was conducted. RESULTS: In total, 521 healthcare workers responded (70.4%). The prevalence of self-reported hand eczema was 9.6% [95% confidence interval (CI): 7.1-12.1%], with 10.8% in nurses and 6.9% in doctors. According to multivariable logistic regression analysis, the prevalence was higher in those who were excessively exposed to hair dye (OR: 3.871, 95% CI: 1.106-13.549) and those having a history of food allergy were at 3.013 (95% CI: 1.314-6.907) times greater risk of having hand eczema than those who did not. The odds of having hand eczema were 4.863 (95% CI: 1.037-22.803) times greater in those who hand washed more than 50 times daily in comparison to those who washed hands less than 10 times per day. The symptoms of hand eczema were mild during the investigation period. CONCLUSIONS: Hand eczema is common among healthcare workers in Guangzhou. The prevention of hand eczema by educational programs is needed for Chinese healthcare workers.

The Correlation Between Tuberous Sclerosis Complex Genotype and Renal Angiomyolipoma Phenotype.

Tuberous sclerosis complex (TSC) is a rare multisystem autosomal dominant genetic disease that occurs between 1 in 6,000 and 1 in 10,000 live births. Additionally, renal angiomyolipoma is the most common form of renal disease in patients affected by TSC. Although a genetic mutation analysis of TSC is not rare, the correlation between the TSC gene mutation and renal angiomyolipoma phenotype is poorly understood. This study aims to analyze the mutation sites in 261 types of selected TSC patients. The results reveal that: (1) female patients develop more renal angiomyolipoma than male patients [p = 0.008, OR = 2.474, 95%CI (1.258-4.864)]; (2). The missense mutation of TSC1 led to a higher risk of renal angiomyolipoma [p < 0.01, OR = 15, 95%CI (2.859-78.691)], and in contrast, showed a reduced risk in patients with frameshift mutation [p = 0.03, OR = 0.252, 95%CI (0.07-0.912)]; (3). Patients with TSC2 mutations in the transcription activation domain 1 coding genes, had increased renal angiomyolipoma [p = 0.019, OR = 3.519, 95%CI (1.226-10.101)]. Therefore, our genotype-phenotype correlation study might shed light on the early monitoring and evaluation of renal angiomyolipoma in TSC patients.

Artesunate alleviates imiquimod-induced psoriasis-like dermatitis in BALB/c mice.

Artesunate (ART), a derivative of artemisinin, is a medication to treat malaria. Beyond that, the anti-inflammatory and immunoregulatory activities of ART have been identified in autoimmune diseases. However, whether ART functions in psoriasis-like dermatitis induced by imiquimod (IMQ, a TLR7/8 agonist) is currently unkown. There, we found that the cumulative score, epidermal thickening and expression of Ki-67 of ART-treated BALB/c mice were significantly lower than those in the IMQ psoriatic model group. In addition, ART treatment ameliorated mice from systemic inflammation. Mechanistically, ART reduced γδ T cells in draining lymph nodes, which might be benefit the improvement of dermatitis. These findings suggested that ART could be a promising drug of psoriasis in clinic.

Identification of Mutation Regions on NF1 Responsible for High- and Low-Risk Development of Optic Pathway Glioma in Neurofibromatosis Type I.

Neurofibromatosis type I is a rare neurocutaneous syndrome resulting from loss-of-function mutations of NF1. The present study sought to determine a correlation between mutation regions on NF1 and the risk of developing optic pathway glioma (OPG) in patients with neurofibromatosis type I. A total of 215 patients with neurofibromatosis type I, from our clinic or previously reported literature, were included in the study after applying strict inclusion and exclusion criteria. Of these, 100 patients with OPG were classified into the OPG group and 115 patients without OPG (aged ≥ 10 years) were assigned to the Non-OPG group. Correlation between different mutation regions and risk of OPG was analyzed. The mutation clustering in the 5' tertile of NF1 was not significantly different between OPG and Non-OPG groups (P = 0.131). Interestingly, patients with mutations in the cysteine/serine-rich domain of NF1 had a higher risk of developing OPG than patients with mutations in other regions [P = 0.019, adjusted odds ratio (OR) = 2.587, 95% confidence interval (CI) = 1.167-5.736], whereas those in the HEAT-like repeat region had a lower risk (P = 0.036, adjusted OR = 0.396, 95% CI = 0.166-0.942). This study confirms a new correlation between NF1 genotype and OPG phenotype in patients with neurofibromatosis type I, and provides novel insights into molecular functions of neurofibromin.

Manganese-enhanced MRI of rat brain based on slow cerebral delivery of manganese(II) with silica-encapsulated Mn x Fe(1-x) O nanoparticles.

In this work, we report a monodisperse bifunctional nanoparticle system, MIO@SiO2 -RITC, as an MRI contrast agent [core, manganese iron oxide (MIO); shell, amorphous silica conjugated with rhodamine B isothiocyanate (RITC)]. It was prepared by thermal decomposition and modified microemulsion methods. The nanoparticles with varying iron to manganese ratios displayed different saturated magnetizations and relaxivities. In vivo MRI of rats injected intravenously with MIO@SiO2-RITC nanoparticles exhibited enhancement of the T1 contrast in brain tissue, in particular a time-delayed enhancement in the hippocampus, pituitary gland, striatum and cerebellum. This is attributable to the gradual degradation of MIO@SiO2-RITC nanoparticles in the liver, resulting in the slow release of manganese(II) [Mn(II)] into the blood pool and, subsequently, accumulation in the brain tissue. Thus, T1-weighted contrast enhancement was clearly detected in the anatomic structure of the brain as time progressed. In addition, T2*-weighted images of the liver showed a gradual darkening effect. Here, we demonstrate the concept of the slow release of Mn(II) for neuroimaging. This new nanoparticle-based manganese contrast agent allows one simple intravenous injection (rather than multiple infusions) of Mn(II) precursor, and results in delineation of the detailed anatomic neuroarchitecture in MRI; hence, this provides the advantage of the long-term study of neural function.

Differential autophagic cell death under stress with ectopic cytoplasmic and mitochondrial-specific PPP2R2B in human neuroblastoma cells.

Protein phosphatase 2A is one of four major classes of serine/threonine phosphatases. Overexpression of brain-specific regulatory subunit PPP2R2 in neuron cells is implicated in pathogenesis. The alternative splicing of PPP2R2B encodes two isoforms. They are subunit of cytoplasmic specific Bß1 and mitochondria-targeted Bß2. The two constructs were transfected into human neuroblastoma cells, SK-N-SH, respectively, and the stable clones overexpressing either Bß1 or Bß2 established. We have reported that Bß2 clones are sensitive to reactive oxygen species (ROS) treatment by inducing autophagic cell death. To study more on the onset of neuropathogenesis under strain, both clones were exposed to different environmental stress, e.g. starvation and endoplasmic reticulum (ER) stress. To learn how PPP2R2B overexpression responds to starvation, cells were incubated in Hank's buffered salt solution of deprived nutrient. Cell death was induced in Bß1 clones after 6 h starvation, but not in Bß2 clones. The pharmacological inhibitor, Bafilomycin A1, rescued the cell death while suppressing autophagy. On the other hand, to assess how cells respond to ER stress, the cells were treated with 0.1 µM of N-glycosylation inhibitor, tunicamycin (TM). In contrast with Bß1, the apoptotic cell death appeared in Bß2 after 48 h treatment. The formation of autophagolysosome was detected in Bß2 following 12 h treatment with TM as evidenced by lysotracker and GFP-LC3 staining for fluorescence microscopy analysis. The autophagy inhibitor, 3-methyladenine, salvaged the final apoptosis. The stable cell lines with ectopically transfected PPP2R2B genes encoding isoforms of brain-specific regulatory subunit exhibit distinct apoptosis under different stressors. The induced autophagic apoptotic cell death is related to mitochondrial membrane potential drop and ROS generation. Disturbance of autophagy alleviates the induced cell death. The results promised a good model for understanding the onset in pathogenesis under stress in neuron cells with aberrant PPP2R2B expression.

Oxidative stress promotes autophagic cell death in human neuroblastoma cells with ectopic transfer of mitochondrial PPP2R2B (Bbeta2).

BACKGROUND: The multifunctional protein phosphatase 2A (PP2A) is a heterotrimeric serine/threonine protein phosphatase composed of a scaffolding, catalytic and regulatory subunits. By modifying various downstream signal transducers, the aberrant expression of the brain-targeted regulatory subunit PPP2R2B is associated with the onset of a panel of neuronal disorders. The alternatively splicing of PPP2R2B encodes two regulatory subunit isoforms that determine cellular distribution of the neuron-specific holoenzyme to mitochondria (Bbeta2) and cytoplasm (Bbeta1), respectively. RESULTS: Human neuroblastoma cells were transfected with PPP2R2B constructs encoding the complete sequences of Bbeta2 and Bbeta1, respectively. The colonies with antibiotic resistance were selected as stable cell lines. Both ectopic Bbeta1 and Bbeta2 clones exhibited characteristics of autophagy. To test how cells respond to reactive oxygen species generators, the cells were treated with either hydrogen peroxide or t-butyl hydroperoxide and Bbeta2 clones induced cell death. Suppression of autophagy using either RNA interference of the essential autophagy gene or pharmacological inhibitor rescued cell death caused by oxidative stress. CONCLUSIONS: Cells with ectopically expressed mitochondria-targeted regulatory subunit PPP2R2B of the holoenzyme PP2A were shown predisposed to autophagy and oxidative stress induced cell death that is related to apoptosis. The results promised a model for studying the mechanism and function of aberrant PPP2R2B expression in neuronal cells. The work provided a new target for understanding and prevention of neuropathogenesis.