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Acetaminophen (APAP) overdose is a major cause of liver injury. Neural precursor cell expressed developmentally downregulated 4-1 (NEDD4-1) is an E3 ubiquitin ligase that has been implicated in the pathogenesis of numerous liver diseases; however, its role in APAP-induced liver injury (AILI) is unclear. Thus, this study aimed to investigate the role of NEDD4-1 in the pathogenesis of AILI. We found that NEDD4-1 was dramatically downregulated in response to APAP treatment in mouse livers and isolated mouse hepatocytes. Hepatocyte-specific NEDD4-1 knockout exacerbated APAP-induced mitochondrial damage and the resultant hepatocyte necrosis and liver injury, while hepatocyte-specific NEDD4-1 overexpression mitigated these pathological events both in vivo and in vitro. Additionally, hepatocyte NEDD4-1 deficiency led to marked accumulation of voltage-dependent anion channel 1 (VDAC1) and increased VDAC1 oligomerization. Furthermore, VDAC1 knockdown alleviated AILI and weakened the exacerbation of AILI caused by hepatocyte NEDD4-1 deficiency. Mechanistically, NEDD4-1 was found to interact with the PPTY motif of VDAC1 through its WW domain and regulate K48-linked ubiquitination and degradation of VDAC1. Our present study indicates that NEDD4-1 is a suppressor of AILI and functions by regulating the degradation of VDAC1.
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Objective:To investigate the efficacy and safety of sequential treatment with tirofiban and argatroban in acute isolated pontine infarction (AIPI) caused by branch atheromatous disease (BAD).Methods:Consecutive patients with AIPI caused by BAD within 48 h of onset and admitted to Zhengzhou Central Hospital from April 2021 to April 2022 were enrolled retrospectively. The patients were divided into sequential treatment group and tirofiban group according to their therapeutic modalities. In the tirofiban group, tirofiban was pumped intravenously within 48 h after admission, and dual antiplatelet therapy with aspirin and clopidogrel was added 4 h before tirofiban was discontinued. On the basis of tirofiban treatment, the sequential treatment group was followed by argatroban for 5 days when tirofiban is discontinued. The main outcome measure was the modified Rankin Scale (mRS) score at 3 months after the onset . A score of <2 was defined as a good outcome. The secondary outcome measure was all the adverse events during the treatment and follow-up. Multivariate logistic regression analysis was used to determine the independent factors of the outcomes. Results:A total of 64 patients with AIPI caused by BAD were enrolled, including 32 in the sequential treatment group and 32 in the tirofiban group. There was no statistical difference in baseline data between the two groups, but the rate of good outcomes at 3 months after onset in the sequential treatment group was significantly higher than that in the tirofiban group (78.1% vs. 50.0%; χ2=5.497, P=0.019). Multivariate logistic regression analysis showed that after adjusting for low-density lipoprotein cholesterol, the higher baseline National Institutes of Health Stroke Scale score was independently associated with the poor outcomes (odds ratio 2.067, 95% confidence interval 1.343-3.182; P=0.001), while the sequential treatment was independently associated with the good outcomes (odds ratio 0.248, 95% confidence interval 0.064-0.957; P=0.043). Conclusion:Early application of sequential treatment with tirofiban and argatroban in AIPI caused by BAD may effectively improve the outcomes of patients, and the safety is good.
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Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis and insulin resistance and there are currently no approved drugs for its treatment. Hyperactivation of mTOR complex 1 (mTORC1) and subsequent impairment of the transcription factor EB (TFEB)-mediated autophagy-lysosomal pathway (ALP) are implicated in the development of NAFLD. Accordingly, agents that augment hepatic TFEB transcriptional activity may have therapeutic potential against NAFLD. The objective of this study was to investigate the effects of nuciferine, a major active component from lotus leaf, on NAFLD and its underlying mechanism of action. Here we show that nuciferine activated ALP and alleviated steatosis, insulin resistance in the livers of NAFLD mice and palmitic acid-challenged hepatocytes in a TFEB-dependent manner. Mechanistic investigation revealed that nuciferine interacts with the Ragulator subunit hepatitis B X-interacting protein and impairs the interaction of the Ragulator complex with Rag GTPases, thereby suppressing lysosomal localization and activity of mTORC1, which activates TFEB-mediated ALP and further ameliorates hepatic steatosis and insulin resistance. Our present results indicate that nuciferine may be a potential agent for treating NAFLD and that regulation of the mTORC1-TFEB-ALP axis could represent a novel pharmacological strategy to combat NAFLD.
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OBJECTIVE@#To develop a cell-based system for the diagnosis of vitamin K-dependent coagulation factor deficiency 1 (VKCFD1).@*METHODS@#In HEK293 cells stably expressing the reporter gene FIX-Gla-PC, the gamma-glutamyl carboxylase (GGCX) gene was knocked out by using CRISPR/Cas9 technology. Enzyme-linked immunosorbent assay (ELISA), DNA sequencing and Western blotting were used to identify the GGCX gene knockout cells. A quickchange point variant method was used to construct the GGCX variant. ELISA was used to assess the influence of GGCX variant on the activity of reporter gene.@*RESULTS@#Two monoclonal cell lines with no reporter activity by ELISA was identified. Edition and knockout of the GGCX gene was confirmed by DNA sequencing and Western blotting. The activity of the reporter gene was recovered by transfection of the wild-type GGCX gene. Thereby two monoclonal cells with GGCX knockout were obtained. By comparing the wild-type and pathogenic GGCX variants, the reporter activity was decreased in the pathogenic variants significantly.@*CONCLUSION@#A cell-based system for the detection of GGCX activity was successfully developed, which can be used for the diagnosis of VKCFD1 caused by GGCX variants.
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In recent years, mass spectrometry has been widely used to study membrane protein structure and function. However, the application of mass spectrometry to study integral membrane protein is limited because there are many hydrophobic amino acids in the trans-membrane domain of integral membrane protein to cause low sequence coverage detected by LC-MS/MS. Therefore, we used vitamin K epoxide reductase (VKORC1), a human integral membrane protein, as a model to optimize the digestion conditions of chymotrypsin, and developed an in-gel digestion method of chymotrypsin to improve sequence coverage of membrane protein by mass spectrometry. By exploring the effects of calcium concentration, pH value and buffer system on the percentage of sequence coverage, number of total detected and types of unique peptide, and the size of unique peptide, sequence coverage and peptide diversity could be considered under condition of Tris-HCl buffer with 5-10 mmol/L calcium ion concentration and pH value 8.0-8.5. This method could make the sequence coverage of membrane protein to reach more than 80%. It could be widely used in the study of membrane protein structure and function, identification of interaction site between membrane proteins, and identification of binding site between membrane protein and small molecular drug.
Subject(s)
Humans , Amino Acid Sequence , Chromatography, Liquid , Chymotrypsin/metabolism , Digestion , Membrane Proteins , Tandem Mass Spectrometry , Trypsin , Vitamin K Epoxide ReductasesABSTRACT
OBJECTIVE@#To investigate the effect of the chemoprotectant tempol on the anti-tumor activity of cisplatin (DDP).@*METHODS@#The cellular toxicity of tempol in human colon cancer SW480 cells and mouse colon cancer CT26 cells were evaluated using MTT and cell counting kit-8 assays. CalcuSyn software analysis was used to determine the interaction between tempol and DDP in inhibition of the cell viability. A subcutaneous homograft mouse model of colon cancer was established. The mice were randomly divided into control group, tempol group, cisplatin group and tempol + DDP treatment group with intraperitoneal injections of the indicated agents. The tumor size, body weight and lifespan of the mice were measured, and HE staining was used to analyze the cytotoxic effect of the agents on the kidney and liver. Immunohistochemistry and Western blotting were performed to detect the expression of Bax and Bcl2 in the tumor tissue, and TUNEL staining was used to analyze the tumor cell apoptosis. The level of reactive oxygen species (ROS) in the tumor tissue was determined using flow cytometry.@*RESULTS@#Tempol showed inhibitory effects on the viability of SW480 and CT26 cells. CalcuSyn software analysis showed that tempol had a synergistic anti-tumor effect with DDP (CI < 1). In the homograft mouse model, tempol treatment alone did not produce obvious anti-tumor effect. HE staining showed that the combined use of tempol and DDP alleviated DDP-induced fibrogenesis in the kidneys, but tempol also reduced the anti-tumor activity of DDP. Compared with the mice treated with DDP alone, the mice treated with both tempol and DDP had a significantly larger tumor size ( < 0.01) and a shorter lifespan ( < 0.05). Tempol significantly reversed DDP-induced expression of Bax and Bcl2 in the tumor tissue and tumor cell apoptosis ( < 0.001), and obviously reduced the elevation of ROS level in the tumor tissue induced by DDP treatment ( < 0.05).@*CONCLUSIONS@#Tempol can attenuate the anti-tumor effect of DDP while reducing the side effects of DDP. Caution must be taken and the risks and benefits should be carefully weighed when considering the use of tempol as an anti-oxidant to reduce the toxicities of DDP.