Expression and significance of SIRT6 in human peritoneal dialysis effluents and peritoneal mesothelial cells.

Sirtuin 6 (SIRT6) can inhibit the fibrosis of many organs. However, the relationship between SIRT6 and peritoneal fibrosis (PF) in peritoneal dialysis (PD) remains unclear. We collected 110 PD patients with a duration of PD for more than 3 months and studied the influence of PD duration and history of peritonitis on SIRT6 levels in PD effluents (PDEs). We also analyzed the relationship between SIRT6 levels in PDEs and transforming growth factor beta 1 (TGF-ß1), IL-6, PD duration, peritoneal function, PD ultrafiltration (UF), and glucose exposure. We extracted human peritoneal mesothelial cells (HPMCs) from PDEs and measured the protein and gene expression levels of SIRT6, E-cadherin, vimentin, and TGF-ß1 in these cells. Based on the clinical results, we used human peritoneal mesothelial cells lines (HMrSV5) to observe the changes in SIRT6 levels and mesothelial-to-mesenchymal transition (MMT) after intervention with PD fluid. By overexpressing and knocking down SIRT6 expression, we investigated the effect of SIRT6 expression on E-cadherin, vimentin, and TGF-ß1 expression to elucidate the role of SIRT6 in mesothelial-to-epithelial transition in PMCs. Results: (1) With the extension of PD duration, the influence of infection on SIRT6 levels in PDEs increased. Patients with the PD duration of more than 5 years and a history of peritonitis had the lowest SIRT6 levels. (2) SIRT6 levels in PDEs were negatively correlated with PD duration, total glucose exposure, TGF-ß1, IL-6 levels, and the dialysate-to-plasma ratio of creatinine (Cr4hD/P), but positively correlated with UF. This indicates that SIRT6 has a protective effect on the peritoneum. (3) The short-term group (PD ≤ 1 year) had higher SIRT6 and E-cadherin gene and protein levels than the mid-term group (1 year < PD ≤ 5 years) and long-term group (PD > 5 years) in PMCs, while vimentin and TGF-ß1 levels were lower in the mid-term group and long-term group. Patients with a history of peritonitis had lower SIRT6 and E-cadherin levels than those without such a history. (4) After 4.25% PD fluid intervention for HPMCs, longer intervention time resulted in lower SIRT6 levels. (5) Overexpressing SIRT6 can lead to increased E-cadherin expression and decreased vimentin and TGF-ß1 expression in HPMCs. Knocking down SIRT6 expression resulted in decreased E-cadherin expression and increased vimentin and TGF-ß1 expression in HPMCs. This indicates that SIRT6 expression can inhibit MMT in HPMCs, alleviate PF associated with PD, and have a protective effect on the peritoneum.

Three new schinortriterpenoids from the leaves of Schisandra chinensis (Turcz.) Baill.

Three undescribed schinortriterpenoids, schinensilactones D-F (1-3), together with five known ones, namely, wuweizidilactone A (4), wuweizidilactone C (5), wuweizidilactone F (6), wuweizidilactone J (7) and wuweizidilactone N (8), were isolated from the leaves of Schisandra chinensis (Turcz.) Baill. The structures of new compounds were established by analysis of their spectroscopic data including MS, IR, 1D- and 2D-NMR spectra. The absolute configuration of 1 was confirmed by single-crystal X-ray diffraction and calculated electronic circular dichroism (ECD) spectra. All compounds were evaluated for their neuroprotective effects against H2O2-induced injury in human neuroblastoma SH-SY5Y cell lines. Cell viability was remarkably reduced to 52.33% in H2O2-treated cells. Compounds 5-7 exhibited moderate neuroprotective activities at 50 µM, with cell viability of 64.84%, 67.34% and 63.73%, respectively.

Melatonin Inhibits Gastric Cancer Cell Proliferation by Suppressing Exosome miR-27b-3p Expression.

BACKGROUND/AIM: In addition to its established role in regulating circadian rhythms and reducing inflammation, melatonin has been demonstrated to possess anti-cancer properties. In this study, we investigated the effects of exosomal miRNAs released by melatonin-treated GC cells on gastric cancer. MATERIALS AND METHODS: To identify the potential exosomal miRNAs involved in the treatment of gastric cancer, we performed exosome small RNA sequencing (sRNA-seq) to screen significant changes in 34 exosomal miRNAs in AGS cells before and after melatonin treatment. CCK-8, wound healing, and transwell invasion assays were used to examine the effects of miRNAs on cancer characteristics. Furthermore, a dual-luciferase reporter gene assay was performed to identify the miRNA targets. RESULTS: Exosomal miR-27b-3p was down-regulated by approximately 1.37-fold following melatonin treatment. The CCK-8 assay revealed a significant increase in cell proliferation in the miR-27b-3p mimic group compared to that in the miR-27b-3p mimic NC group. In the wound healing assay, cells treated with miR-27b-3p mimics displayed significantly more rapid wound closure than that observed in the miR-27b-3p mimic NC group. The transwell invasion assay revealed a substantial increase in the number of invading cells in the miR-27b-3p mimic group compared to that in the miR-27b-3p mimic NC group. Additional analysis revealed that miR-27b-3p directly targets ADAMTS5 and that its up-regulation results in increased proliferation, invasion, and metastasis of GC cells. CONCLUSION: Melatonin suppressed the progression of gastric cancer by regulating the exosomal miR-27b-3p-ADAMTS5 pathway. Thus, melatonin represents a promising potential therapeutic agent for patients with gastric cancer.

Mallory-Weiss syndrome in four hemodialysis patients: a case study.

BACKGROUND: Hemodialysis patients are prone to gastrointestinal bleeding, and Mallory-Weiss syndrome (MWS) is one of the causes. Mallory-Weiss syndrome is often induced by severe vomiting, manifests as upper gastrointestinal bleeding, and is self-limited with a good prognosis. However, mild vomiting in hemodialysis patients can lead to the occurrence of MWS, and the mild early symptoms are easy to misdiagnose, leading to the aggravation of the disease. CASE PRESENTATION: In this paper, we report four hemodialysis patients with MWS. All patients displayed symptoms of upper gastrointestinal bleeding. The diagnosis of MWS was confirmed by gastroscopy. One patient had a history of severe vomiting; however, the other three reported histories of mild vomiting. Three patients received the conservative hemostasis treatment, and the gastrointestinal bleeding stopped. One patient underwent the gastroscopic and interventional hemostasis treatments. The conditions of three of the patients improved. Unfortunately, one of the patients died due to the cardia insufficiency. CONCLUSIONS: We think that the mild symptoms of MWS are easily covered up by other symptoms. This may lead to delays in diagnosis and treatment. For patients with severe symptoms, gastroscopic hemostasis is still the first choice, and interventional hemostasis can also be considered. For patients with mild symptoms, drug hemostasis is the first consideration.

Awareness of initiative practice for health in the Chinese population: A questionnaire survey based on a network platform.

BACKGROUND: In 2016, the Chinese government issued the Healthy China 2030 plan, which also produced the initiative practice for health (IPFH) concept. However, people's knowledge and awareness of the IPFH are unclear. AIM: To investigate awareness of IPFH in the Chinese population and explore the relevant influential factors. METHODS: An internet-based self-designed questionnaire survey was used to collect respondents' demographic characteristics and awareness of health and the IPFH from March 26 to April 18, 2020. IPFH consciousness was assessed by the scores for different related questions. The Student's t test, the Chi-square test, and multiple logistic regression analysis were performed to analyze the differences and influencing factors. RESULTS: A total of 2678 valid questionnaires were collected. Of the respondents, 973 (36.3%) had heard of the IPFH concept. In addition, 89.5% of participants agreed with the view that the IPFH is beneficial to improving quality of life, and over half thought that a regular schedule, a reasonable diet, tobacco and alcohol control, a cheerful mood, specific life goals and plans, taking the initiative to accept health-related education and implement health knowledge, good interpersonal relationships, and regular physical examinations were closely related to the IPFH. The majority of respondents paid attention to their health and usually obtained health-related knowledge via social media and were also willing to promote the IPFH. Most of the participants underestimated the role of hospitals, family doctors, and health managers in promoting the IPFH. Age, monthly income, and medical-related work experience were the influencing factors for IPFH awareness. CONCLUSION: The Chinese population has limited knowledge of the IPFH. People with strong IPFH awareness are older, earn more, and have medical-related work experience.

Schisandraceae triterpenoids: A review of phytochemistry, bioactivities and synthesis.

ETHNOPHARMACOLOGICAL RELEVANCE: Plants of the Schisandraceae family have a rich and medicinal history dating back to ancient times. Many of them are used as folk medicine in the treatment of chronic coughs, asthma, nocturnal emission, spontaneous sweating, night sweats, palpitation, insomnia and thirst. AIM OF THE REVIEW: The current review is carried out on triterpenoids from the Schisandraceae family, aiming to comprehensively summarize their phytochemistry, pharmacology and synthesis and provide new insights to the chemical and pharmacological study and rational utilization on medicinal plants of the Schisandarceae family. MATERIALS AND METHODS: The information was searched from the scientific literature published from June 2014 to November 2021 on the online databases (including PubMed, CNKI, Elsevier, SciFinder and Web of Science) and other bibliography (e.g. the Chinese Pharmacopoeia, 2020 edition, Chinese herbal books). The scientific literature related to phytochemistry, pharmacology, biological activites and synthesis of triterpenoids from the Schisandraceae family was gathered. RESULTS: From June 2014 to November 2021, there were approximately 211 novel triterpenoids isolated and identified from 18 species of the Schisandraceae family. These compounds exhibit tremendous diversity in their structures, and some of them possess promising pharmacological activities, including anti-viral, anti-tumor, anti-inflammatory, hepatoprotective, immunosuppressive activities and neuroprotective effects. In the attempt to synthesize active compounds, the total synthesis of 13 schinortriterpenoids belonging to five structural types was successfully completed. CONCLUSIONS: Studies of triterpenoids from the Schisandraceae family are well documented in this review (from June 2014 to November 2021), and it is also well acknowledged that they are valuable resources with medicinal efficacy. However, relevant pharmacological studies are limited to in vitro tests, and data from in vivo studies and toxicology are lacking or unavailable. Fortunately, there is growing interest in the synthesis of active compounds, which should serve as an approach for accessing active compounds to develop in vivo or toxicity studies, with a view of clarifying their in vitro and vivo mechanisms for more effective and safe natural drugs.

Horseshoe kidney with PLA2R-positive membranous nephropathy.

BACKGROUND: Horseshoe kidney (HSK) is a common congenital defect of the urinary system. The most common complications are urinary tract infection, urinary stones, and hydronephrosis. HSK can be combined with glomerular diseases, but the diagnosis rate of renal biopsy is low due to structural abnormalities. There are only a few reports on HSK with glomerular disease. Here, we have reported a case of PLA2R-positive membranous nephropathy occurring in a patient with HSK. CASE PRESENTATION: After admission to the hospital due to oedema of both the lower extremities, the patient was diagnosed with nephrotic syndrome due to abnormal 24-h urine protein (7540 mg) and blood albumin (25 g/L) levels. Abdominal ultrasonography revealed HSK. The patient's brother had a history of end-stage renal disease due to nephrotic syndrome. Therefore, the patient was diagnosed with PLA2R-positive stage II membranous nephropathy through renal biopsy under abdominal ultrasonography guidance. He was administered adequate prednisone and cyclophosphamide, and after 6 months of treatment, urinary protein excretion levels significantly decreased. CONCLUSION: The risk and difficulty of renal biopsy in patients with HSK are increased due to structural abnormalities; however, renal biopsy can be accomplished through precise positioning with abdominal ultrasonography. In the literature, 20 cases of HSK with glomerular disease have been reported thus far. Because of the small number of cases, estimating the incidence rate of glomerular diseases in HSK is impossible, and the correlation between HSK and renal pathology cannot be stated. Further studies should be conducted and cases should be accumulated to elucidate this phenomenon.

Chinese Medicine Involving Triple Rehabilitation Therapy for Knee Osteoarthritis in 696 Outpatients: A Multi-Center, Randomized Controlled Trial.

OBJECTIVE: To determine the effects of Chinese medicine (CM) involving triple rehabilitation therapy on the progression of knee osteoarthritis (KOA). METHODS: A total of 722 patients recruited from 38 community health service centers located in China from March 2013 to March 2017 were randomly divided into treatment and control groups equally, using a cluster randomization design. Health education combined with CM involving triple rehabilitation therapy for KOA (electro-acupuncture, Chinese medicinal herb fumigating-washing, and traditional exercises) was administered in the treatment group while conventional rehabilitation therapy (physical factor therapy, joint movement training, and muscle strength training) was administered in the control group. Patients with a visual analog scale (VAS) scores ≽4 were treated with dispersible meloxicam tablets (7.5 mg, once daily). The Lequesne index scores, VAS scores, range of motion (ROM), lower limb muscle strength, knee joint circumference, quantitative scores of KOA symptoms, and the short-form 36 item health survey questionnaire (SF-36) scores were measured for each patient at 5 checkpoints (before treatment, at the 2nd week and the 4th week during the 4-week treatment period, at 1 month and 3 months after end of treatment), and adverse reactions were observed also. RESULTS: A total of 696 patients completed the entire process, with 351 in the treatment group and 345 in the control group. At all treatment checkpoints, the treatment group demonstrated better outcomes than the control group with regard to the total Lequesne index scores, effective rate and improvement rate of the total Lequesne index scores, VAS scores, lower limb muscle strength, knee circumference, quantitative scores of KOA symptoms, and SF-36 scores as well (P<0.05 or P<0.01). No adverse reactions were encountered in this study. CONCLUSIONS: CM involving triple rehabilitation therapy can alleviate KOA-related pain and swelling, improve lower limb muscle strength, promote flexion and activity of the knee and improve the quality of life in patients undergoing KOA. It is suitable for patients with early or mid-stage KOA. (Registration No. ChiCTR-TRC-12002538).

Exosomal miR-155-5p promotes proliferation and migration of gastric cancer cells by inhibiting TP53INP1 expression.

Exosomal microRNA (miRNA) secreted by tumor cells plays an important biological role in tumorigenesis and development. We aimed to explore the effects of exosomal miR-155-5p in gastric cancer (GC) and understand its mechanism of action in GC progression. We isolated exosomes from the human gastric mucosal epithelial cell line GES-1 and gastric cancer cell line AGS, and then identified them according to their surface markers by flow cytometry. Later, we detected the miR-155-5p expression levels in tissues and isolated exosomes using RT-qPCR. Bioinformatics analysis showed that miR-155-5p directly binds to the 3' untranslated region (3'-UTR) of tumor protein p53-induced nuclear protein 1 (TP53INP1) mRNA. We also investigated whether the miR-155-5p-rich exosomes caused changes in cell cycle, proliferation, and migration in AGS cells. In this study, we found that the levels of miR-155-5p were significantly increased in GC tissues and AGS cells, and that the TP53INP1 protein level was downregulated in GC tissues using IHC and IFC. TP53INP1 was found to be directly regulated by miR-155-5p following a dual luciferase-based reporter assay. After co-culturing with the isolated miR-155-5p-rich exosomes, the proliferation and migration capabilities of AGS cells were enhanced. Thus, our results reveal that exosomal miR-155-5p acts as an oncogene by targeting TP53INP1 mRNA in human gastric cancer.

CRISPR/Cas9-mediated knockout of the PDEF gene inhibits migration and invasion of human gastric cancer AGS cells.

Gastric cancer is one of the most common malignant tumors worldwide and has the second highest incidence and mortality rate among malignant tumors in China. Prostate-derived Ets factor (PDEF) is a member of the Ets family of transcription factors. Although PDEF plays an important role in tumorigenesis, its biological function in gastric cancer is still unclear. Here, we evaluated PDEF expression in 30 cases of human gastric carcinoma and the corresponding peritumoral tissues, using immunohistochemistry and immunofluorescence. Significantly higher levels of PDEF were detected in tumors compared to peritumoral tissues. We then investigated PDEF expression in the gastric cancer cell lines SGC and AGS and the normal gastric epithelial cell line GES; The CRISPR/Cas9 genome-editing system was used to knockout PDEF in AGS cells as a model for gastric cancer. Cell proliferation, apoptosis, migration, and invasion of PDEF-knockout AGS cells were evaluated using CCK-8, flow cytometry, scratch wound, and transwell assays, respectively. The results illustrated that PDEF-knockout inhibited AGS cell proliferation, migration, and invasion. Taken together, the results imply that PDEF plays important roles in the proliferation, migration, and invasion of AGS cells and may serve as a new treatment target in gastric cancer.

[Effects of LncRNA H19 on Proliferation of Human Colorectal Cancer SW620 Cells].

OBJECTIVE: To determine the expression level of long non-coding RNA (lncRNA) imprinted maternallyexpressed transcript (H19) in colorectal cancer tissues and its effect on proliferation of colorectal cancer SW620 cells. METHODS: Real-time quantitative PCR (qRT-PCR) was applied to detect the expression of H19 in 20 paired tumor tissues and adjacent normal tissues,and in normal NCM460 cells and colorectal cancer SW480,HCT116 and SW620 cells. The specific small interfering RNA for H19 (si-H19 group) or negative control sequence (si-NC group) were transfected into SW620 cells. Proliferation of the transfected cells was detected using flow cytometry,CCK8 assay and clone formation experiment. The expressions of CyclinD1 and cyclin dependent kinase 4 (CDK4) were detected by qRT-PCR and Western blot. RESULTS: The expression levels of H19 in colorectal cancer tissues and cells were higher compared with those in adjacent normal tissues and normal NCM460 cells. Lower H19 level,cell activities and cell clone numbers were found in si-H19 transfected cells compared with those in si-NC transfected cells ( P<0.05). si-H19transfected cells had decreased expression of CyclinD1 and CDK4 ( P<0.05). CONCLUSION: H19expression in colorectal cancer is high. Knock-down H19 expression can inhibit proliferation of colorectal cancer cells,which provides a potential strategy for targeted therapy of colorectal cancer.

Overexpression of CST4 promotes gastric cancer aggressiveness by activating the ELFN2 signaling pathway.

Gastric cancer is one of the most lethal malignancies of gastrointestinal cancer and its prognosis remains dismal because of the paucity of effective therapeutic targets. Here, we show that cystatin 4 (CST4) is markedly upregulated in gastric cancer cell lines and clinical tissues. Ectopic expression of CST4 in gastric cancer cells promoted proliferation, migration, and invasion of gastric cancer cells in vitro. Furthermore, CST4 overexpression significantly promoted the tumorigenicity of gastric cancer cells in vivo, whereas silencing endogenous CST4 caused an opposite outcome. In addition, extracellular leucine rich repeat and fibronectin type III domain containing 2 (ELFN2) was identified as a downstream target of CST4 in gastric cancer cells and was positively correlated with ELFN2 expression in gastric cancer tissues. Finally, we demonstrated that CST4 enhanced gastric cancer aggressiveness by regulating ELFN2 signaling. Together, our results provide new evidence that CST4 overexpression promotes the progression of gastric cancer and might represent a novel therapeutic target for its treatment.

TMPyP4-regulated cell proliferation and apoptosis through the Wnt/ß-catenin signaling pathway in SW480 cells.

BACKGROUND: The aim of this study was to investigate the potential effects of the 5, 10, 15, 20-tetrakis (1-methylpyridinium-4-yl) porphyrin (TMPyP4) on the proliferation and apoptosis of SW480 cells and the underlying mechanisms by which TMPyP4 exerted its actions. METHODS: After treated with different doses of TMPyP4, cell viability was determined by MTT method, the apoptosis was observed by flow cytometry (FCM) and the expression of Wnt, GSK-3ß, ß-catenin and cyclinD1 was measured by RT-PCR and Western blot analysis. RESULTS: The analysis revealed that TMPyP4 potently suppressed cell viability and induced the apoptosis of SW480 cells in a dose-dependent manner. In addition, the downregulation of Wnt, ß-catenin and cyclinD1 expression levels was detected in TMPyP4-treated SW480 cells. However, followed by the block of Wnt signaling pathway using siRNA methods, the effects of TMPyP4 on proliferation and apoptosis of SW480 cells were significantly reduced. CONCLUSION: It indicates that the TMPyP4-inhibited proliferation and -induced apoptosis in SW480 cells was accompanied by the suppression of Wnt/ß-catenin signaling pathway. Therefore, TMPyP4 may represent a potential therapeutic method for the treatment of colon carcinoma.

[Variation characteristics of total gaseous mercury at Wuzhi mountain (Wuzhishan) background station in Hainan].

Total gaseous mercury (TGM) was continuously monitored at Wuzhi mountain (Wuzhishan) using the high-resolution automatic atmospheric mercury vapor analyzer (Tekran 2537B) from May 2011 to May 2012. The annual geometric mean TGM concentration was (1.58 ± 0.71) ng x m(-3), suggesting that the atmosphere was not obviously polluted. The TGM level at WuZhi mountain remained low from June to August in 2011 and from March to May in 2012, while higher values were observed from September in 2011 to January in 2012. Tropical monsoons played an important role in the monthly variation of TGM. TGM concentrations showed a clear diurnal trend with the minimum concentration occurring at 09:00 AM and the peak concentration at 19:00 PM due to the combined impact of the long-range transport of atmospheric mercury and local meteorological conditions. The temporal trend of TGM highlighted the impact of long-range transport from the mainland of China on the distribution of TGM in ambient air at Wuzhi mountain by the results of backward trajectory analysis using HYSPLIT.

Compare the differences of synonymous codon usage between the two species within cardiovirus.

BACKGROUND: Cardioviruses are positive-strand RNA viruses in the Picornaviridae family that can cause enteric infection in rodents and also been detected at lower frequencies in other mammals such as pigs and human beings. The Cardiovirus genus consists two distinct species: Encephalomyocarditis virus (EMCV) and Theilovirus (ThV). There are a lot differences between the two species. In this study, the differences of codon usage in EMCV and ThV were compared. RESULTS: The mean ENC values of EMCV and ThV are 54.86 and 51.08 respectively, higher than 40.And there are correlations between (C+G)12% and (C+G)3% for both EMCV and ThV (r = -0.736; r = 0.986, P < 0.01, repectively). For ThV the (C+G)12%, (C+G)3%, axis f'1 and axis f'2 had a significant correlations respectively but not for EMCV. According to the RSCU values, the EMCV species seemed to prefer U, G and C ending codon, while the ThV spice seemed to like using U and A ending codon. However, in both genus AGA for Arg, AUU for Ile, UCU for Ser, and GGA for Gly were chosen preferentially. Correspondence analysis detected one major trend in the first axis (f'1) which accounted for 22.89% of the total variation, and another major trend in the second axis (f'2) which accounted for 17.64% of the total variation. And the plots of the same serotype seemed at the same region at the coordinate. CONCLUSION: The overall extents of codon usage bias in both EMCV and ThV are low. The mutational pressure is the main factor that determines the codon usage bias, but the (C+G) content plays a more important role in codon usage bias for ThV than for EMCV. The synonymous codon usage pattern in both EMCV and ThV genes is gene function and geography specific, but not host specific. Maybe the serotype is one factor effected the codon bias for ThV, and location has no significant effect on the variations of synonymous codon usage in these virus genes.

Expression and modification of ARC (apoptosis repressor with a CARD domain) is distinctly regulated by oxidative stress in cancer cells.

Apoptosis repressor with a CARD domain (ARC), which has been shown to protect against oxidative stress-induced apoptosis, was initially found to be highly expressed in terminally differentiated tissues like heart and skeletal muscle. Recently, we and others have found that ARC is also expressed at high levels in multiple cancer tissues and cell lines. Here, we compared the regulation of ARC in response to oxidative stress between cancer cells and other types of cells. Similar to cardiomyocyte cell line H9c2 cells, cancer cells with reduced ARC expression were significantly more sensitive to oxidative stress. However, oxidative stress did not down-regulate ARC expression in cancer cells as it did in H9c2 cells. We further found that in H9c2 cells oxidative stress regulates ARC protein expression post-translationally through proteasome-mediated degradation. In cancer cell line HeLa, the majority of ARC exists in phosphorylated state in the absence of oxidative stress, whereas in H9c2 cells only marginal amount of ARC was phosphorylated under similar conditions. Our data suggest that the high level of ARC protein and the constitutive phosphorylation of ARC in cancer cells may play an important role in the protection of cancer cells against oxidative stress.

ARC protects rat cardiomyocytes against oxidative stress through inhibition of caspase-2 mediated mitochondrial pathway.

Apoptosis repressor with a CARD domain (ARC) has been demonstrated to protect heart cells against ischemia/reperfusion (I/R) injury. In this study, we investigated the mechanism by which ARC protects heart cells against oxidative stress. We monitored the extent of apoptosis and activity of multiple components of the intrinsic apoptotic pathway in rat cardiac myoblast cell line H9c2 with either reduced or increased expression of ARC during oxidative stress. Overexpression of ARC-inhibited oxidative stress-induced caspase-2/3 activation, cytochrome c release, and translocation of Bax to mitochondria. Furthermore, phosphorylation of ARC at threonine 149 was found to be critical to its function. ARC containing a T149A mutation failed to translocate to mitochondria, did not inhibit caspase-2 activation, and had a dominant negative effect against the protective effect of endogenous ARC during oxidative stress. In addition, wild-type ARC but not the T149A mutant inhibited cell death induced by overexpression of caspase-2. Using a yeast two-hybrid (YTH) screening approach and co-immunoprecipitation (Co-IP), we found that protein phosphatase 2C (PP2C) interacted with ARC and that PP2C mediated-dephosphorylation of ARC inhibited its anti-apoptotic activity. Eliminating either the N-terminal CARD domain or the C-terminal P/E domain also abolished the anti-apoptotic function of ARC, suggesting that full-length ARC is required for its apoptotic inhibition. These results indicate that ARC plays an important role in protection of H9c2 cells against oxidative stress-induced apoptosis by phosphorylation-dependent suppression of the mitochondria-mediated intrinsic pathway, partially initiated through the activation of caspase-2.