The Vif (viral infectivity factor) protein of human immunodeficiency virus type-1 (HIV-1) is critical for HIV-1 infectivity. CBF-β is required for HIV-1 Vif function, as it increases the steady-state ...level of the HIV-1 Vif protein to promote host restriction factor APOBEC3 degradation. However, the precise mechanism by which CBF-β promotes HIV-1 Vif levels remains unclear. In the present study, we provided evidences that CBF-β promoted steady-state levels of HIV-1 Vif by inhibiting the degradation of HIV-1 Vif through the proteasome pathway. Our results reveal a new mechanism by which a cellular protein supports viral infectivity by inhibiting viral protein degradation.
•CBF-β blocks the proteasomal degradation of HIV-1 Vif.•HIV-1 Vif lysine free mutant is insensitive to CBF-β.•Altering Vif-CBF-β interaction presents a target for anti-HIV-1 drug design.
•1-MCP reduced browning and delayed quality deterioration of lotus root slices.•1-MCP treatment inhibited the phenolic metabolism of fresh-cut lotus root slices.•1-MCP treatment induced the ...antioxidant system of fresh-cut lotus root slices.•1-MCP were involved in the regulation of ethylene biosynthesis and signal transduction.
The quality of fresh-cut lotus root slices is greatly affected by enzymatic browning. In this study, we investigated the effects of 1-methylcyclopropene treatment on browning and quality deterioration of lotus root slices. When fresh-cut lotus root slices were immersed in 0.1 mg L−1 1-MCP for 1 h and stored at 10 ℃ for twelve days, microbial growth, respiration, total phenolic content, phenylalanine ammonia lyase activity, polyphenol oxidase activity, and soluble quinone levels in fresh-cut lotus root slices were suppressed. Furthermore, 1-MCP treatment improved the antioxidant capacities, peroxidase activities, superoxide dismutase activities, catalase activities, and DPPH free radical scavenging rates in fresh-cut lotus root slices. In addition, 1-MCP treatment inhibited the production of reactive oxide species, which delayed quality deterioration of fresh-cut lotus root slices. Based on transcriptomics and real-time quantitative PCR results, gene expression levels of NnmetK2, NnACO, NnETR2, NnEIN3, and NnERF1 were up-regulated while expression levels of NnEBF1 were down-regulated. These findings indicate that 1-MCP inhibits ethylene biosynthesis and signal transduction, which suppresses a series of ethylene-induced physiological and biochemical reactions. Based on our findings, we propose a new strategy for inhibiting enzymatic browning in fresh-cut lotus root slices.
•The higher the temperature, the more serious the browning in fresh-cut lotus root.•NnPAL1, NnPPOA and NnPOD1-6 were induced by high temperature during storage.•NnPAL1, NnPPOA and NnPOD1-6 could be ...the candidate genes for lotus root browning.
Lotus root (Nelumbo nucifera G.) is an important aquatic vegetable in China. Browning easily during the processing and storage reduces the value of lotus root. Therefore, browning is an important issue for the lotus root industry. PAL, PPO and POD genes were reported as being involved in fruit and vegetable tissue browning, and PAL, PPO and POD enzymes have long been associated with lotus root browning. However, the molecular mechanism of PAL, PPO and POD involved in fresh-cut lotus root browning is poorly understood. This paper analyses the effect of different temperatures on the phenolic content, browning, PPO, PAL and POD enzyme activity and the expression pattern of PPO, PAL and POD genes in fresh-cut lotus root. The results show that the change of PAL, PPO and POD enzymatic activity occurs in parallel with the increase in browning degree in storage at different temperatures. Furthermore, the total phenol content and PAL enzyme activity changes are basically identical, suggesting that PAL might be the key genes involved in the synthesis of total phenol content. Two NnPAL, 2 NnPPO and 7 NnPOD genes were isolated using RNA-seq, and the upregulation of NnPAL1, NnPPOA, NnPOD1, NnPOD2, NnPOD3, NnPOD4, NnPOD5 and NnPOD6 by high temperature coincided with the increase in related enzyme activities and the browning degree of fresh-cut lotus root, which should be considered the most important candidates for fresh-cut lotus root browning.
The phytohormone ethylene responds positively to abiotic stress, but its effect on quality deterioration of fresh-cut Chinese water chestnuts (CWCs) caused by mechanical damage remains unclear. Here, ...the effects of single or combination treatments of ethephon (ET) and 1-methylcyclopropene (1-MCP) on fresh-cut CWCs during storage at 10 °C for 5 d were investigated. The results indicated that ET treatment was most effective in maintaining CWCs’ visual quality, followed by 1-MCP preceding ET treatment, 1-MCP treatment, and 1-MCP following ET treatment. Compared with 1-MCP treatment group, ET-treated fruit exhibited lower expressions of CwPAL, CwCHS1 and CwCHI1 and decreased activity of phenylalanine ammonia-lyase activity to inhibit flavonoid accumulation but higher catalase and superoxide dismutase and peroxidase (POD) activities and lower malonaldehyde content to maintain reactive oxygen species balance and suppress microbial growth. Nevertheless, ET treatment promoted fruit weight loss and CO2 concentration in the package, which was reversed by the preceding 1-MCP application rather than the subsequent 1-MCP treatment. 1-MCP followed by ET treatment not only inhibited the levels of flavonoid compounds and oxidation catalyzed by POD compared with the post-1-MCP treatment, but also reduced H2O2 production and microbial spoilage with a higher catalase activity. These results show that ET could maintain the quality of fresh-cut CWC by boosting antioxidant capacity, inhibiting microbial growth and suppressing enzymatic generation of browning substrates. In addition, compared with ET treatment, 1-MCP followed by ET treatment, despite showing weaker antioxidant enhancement, could inhibit the senescence of fresh-cut CWCs, suggesting its suitability for quality control of fresh-cut CWCs.
•Single or combination treatments of 1-MCP and ethephon maintained quality.•Ethephon was more effective than 1-MCP in alleviating browning.•Post-1-MCP ethephon treatment alleviated browning and inhibited senescence.•Downregulation of CwCHI1 might inhibit the biosynthesis of flavonoids.
The canonical function of phosphodiesterase 3A (PDE3A) is to hydrolyze the phosphodiester bonds in second messenger molecules, such as cyclic AMP (cAMP) and cyclic guanosine monophosphate (cGMP). ...Recently, a phosphodiesterase-activity-independent role for PDE3A was reported. In this noncanonical function, PDE3A physically interacts with Schlafen 12 (SLFN12) upon treatment of cells with cytotoxic PDE3A modulators. Here, we confirmed that the cytotoxic PDE3A modulators act as molecular glues to initiate the association of PDE3A and SLFN12. The PDE3A-SLFN12 interaction increases the protein stability of SLFN12 located in the cytoplasm, while at the same time also inducing SLFN12 dephosphorylation (including serines 368 and 573). Mutational analysis demonstrates that dephosphorylation is required for cell death induced by cytotoxic PDE3A modulators. Finally, we found that dephosphorylation promoted the rRNA RNase activity of SLFN12 and show that this nucleolytic activity is essential for SLFN12’s cell-death-inducing function. Thus, our study deepens the understanding of the biochemical mechanisms underlying SLFN12-mediated cell death.
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•Multiple cytotoxic PDE3A modulators act as molecular glues•PDE3A-SLFN12 interaction reduces the phosphorylation of SLFN12•Dephosphorylation of SLFN12 increases SLFN12’s RNase activity
Yan et al. find that multiple PDE3A modulators act as molecular glues that promote PDE3A-SLFN12 interaction, which results in dephosphorylation of SLFN12. Mutational analyses demonstrate that dephosphorylation of SLFN12 is required for SLFN12’s cell-death-inducing function, which is mediated through SLFN12’s RNase activity against rRNAs.
•Cinnamaldehyde inhibited CWCs browning via different pathways.•Comprehensive exploration of the mechanism of action of cinnamaldehyde on CWCs.•Carefully evaluate changes in CWCs in storage.
The ...quality of fresh-cut Chinese water chestnuts (CWCs) rapidly deteriorates with prolonged storage time, thus affecting its commercial value. This study aimed to investigate the effect of cinnamaldehyde (CA) treatment on the quality of fresh-cut CWCs and its mechanism of action. CA treatment maintained good appearance and higher total soluble solids content (TSS) of fresh-cut CWCs and also significantly inhibited microbial proliferation, respiration, phenylalanine ammonia-lyase activity (PAL) and enzymatic browning substance content. Moreover, CA treatment increased the antioxidant capacity and defense function-related enzyme activities (PPO and POD) of fresh-cut CWCs, and suppressed ·OH production rate and MDA content. Meanwhile, CA treatment significantly increased the content of antioxidant compounds and enzyme activities of the AsA-GSH cycle system. In conclusion, CA can inhibit surface discoloration of fresh-cut CWCs and extend their shelf life, thus increasing their commercial value.
Lentiviruses threaten human and animal health. Virion infectivity factor (Vif) is essential for the infectivity of most lentiviruses, except for the equine infectious anaemia virus (EIAV). Vif ...promotes viral infectivity by recruiting a Cullin-based E3 ligase to induce the degradation of a class of host restriction factors, named APOBEC3. Core binding factor beta (CBF-β) is necessary for several primate lentiviral Vif functions, including HIV-1 Vif. Although much progress has been made in understanding the contribution of CBF-β to Vif function, the precise mechanism has not yet been fully elucidated. In this study, we found that an interaction with CBF-β altered the oligomerization and subcellular distribution pattern and increased the stability of two primate lentiviral Vifs, HIV-1 Vif and Macaca simian immunodeficiency virus (SIVmac) Vif. Moreover, using a CBF-β loss-of-function mutant, we demonstrated that the interaction between CBF-β and Vif was not sufficient for Vif assistance; a region including F68 in CBF-β was also required for the stability and function of Vif. For the first time, this study separates the binding and regulating processes of CBF-β when it is promoting Vif function, which further extends our understanding of the biochemical regulation of Vif by CBF-β.
Summary
Preoperative bone density assessment is necessary to predict screw loosening. The forearm BMD is a useful predictor of BMD-related complications after lumbar operation. Our results show that ...the forearm BMD is as effective a predictor of screw loosening as the lumbar average HU value. Measurement of the forearm BMD may be a useful adjunct in predicting screw loosening following lumbar fusion.
Purpose
To determine the relationship between forearm bone mineral density (BMD) and the risk of pedicle screw loosening in patients with lumbar spondylolisthesis.
Methods
We retrospectively evaluated 270 patients who underwent posterior lumbar interbody fusion for lumbar spondylolisthesis. The patients were divided into two groups on the basis of the with or without loose screws: the loosening group and the non-loosening group. The patient’s gender, age, BMI, smoking and diabetes histories, and the operative segment were recorded as the basic information. The Hounsfield unit (HU) value for the BMD of the L1-4 lumbar was measured using computed tomography. The patient’s distal one-third of the length of the radius and ulna of the non-dominant forearm was chosen as the site for dual-energy X-ray (DXA) bone density testing.
Results
The rate of screw loosening was 13% at a minimum 12 months follow-up. Average forearm BMD (0.461 ± 0.1 vs 0.577 ± 0.1,
p
< 0.001) and mean HU value (L1-4) (121.1 ± 27.3 vs 155.6 ± 32.2,
p
< 0.001) were lower in the screw loosening group than those in the non-loosening group. In multivariate logistic regression analysis, the forearm BMD (OR 0.840; 95%CI 0.797–0.886) and HU value (L1-4) (OR 0.952; 95%CI 0.935–0.969) were independent risk factor for screw loosening. The area under the curve (AUC) for the forearm BMD and HU value for prediction of pedicle screw loosening was 0.802 and 0.811. The forearm BMD cut-off for predicting pedicle screw loosening was 0.543 (sensitivity, 0.800; specificity, 0.864).
Conclusions
The forearm BMD was an independent risk factor for loosening of the lumbar pedicle screws. The forearm BMD was a valid predictor of pedicle screw loosening in patients undergoing lumbar fusion, as was the CT HU value.
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