Parkin-mediated K63-polyubiquitination targets ubiquitin C-terminal hydrolase L1 for degradation by the autophagy-lysosome system.

Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a key neuronal deubiquitinating enzyme which is mutated in Parkinson disease (PD) and in childhood-onset neurodegenerative disorder with optic atrophy. Furthermore, reduced UCH-L1 protein levels are associated with a number of neurodegenerative diseases, whereas up-regulation of UCH-L1 protein expression is found in multiple types of cancer. However, very little is known about how UCH-L1 protein level is regulated in cells. Here, we report that UCH-L1 is a novel interactor and substrate of PD-linked E3 ubiquitin-protein ligase parkin. We find that parkin mediates K63-linked polyubiquitination of UCH-L1 in cooperation with the Ubc13/Uev1a E2 ubiquitin-conjugating enzyme complex and promotes UCH-L1 degradation by the autophagy-lysosome pathway. Targeted disruption of parkin gene expression in mice causes a significant decrease in UCH-L1 ubiquitination with a concomitant increase in UCH-L1 protein level in brain, supporting an in vivo role of parkin in regulating UCH-L1 ubiquitination and degradation. Our findings reveal a direct link between parkin-mediated ubiquitin signaling and UCH-L1 regulation, and they have important implications for understanding the roles of these two proteins in health and disease.

Motor and sensory neuropathy due to myelin infolding and paranodal damage in a transgenic mouse model of Charcot-Marie-Tooth disease type 1C.

Charcot-Marie-Tooth disease type 1C (CMT1C) is a dominantly inherited motor and sensory neuropathy. Despite human genetic evidence linking missense mutations in SIMPLE to CMT1C, the in vivo role of CMT1C-linked SIMPLE mutations remains undetermined. To investigate the molecular mechanism underlying CMT1C pathogenesis, we generated transgenic mice expressing either wild-type or CMT1C-linked W116G human SIMPLE. Mice expressing mutant, but not wild type, SIMPLE develop a late-onset motor and sensory neuropathy that recapitulates key clinical features of CMT1C disease. SIMPLE mutant mice exhibit motor and sensory behavioral impairments accompanied by decreased motor and sensory nerve conduction velocity and reduced compound muscle action potential amplitude. This neuropathy phenotype is associated with focally infolded myelin loops that protrude into the axons at paranodal regions and near Schmidt-Lanterman incisures of peripheral nerves. We find that myelin infolding is often linked to constricted axons with signs of impaired axonal transport and to paranodal defects and abnormal organization of the node of Ranvier. Our findings support that SIMPLE mutation disrupts myelin homeostasis and causes peripheral neuropathy via a combination of toxic gain-of-function and dominant-negative mechanisms. The results from this study suggest that myelin infolding and paranodal damage may represent pathogenic precursors preceding demyelination and axonal degeneration in CMT1C patients.

Classification and Prediction of Food Safety Policy Tools in China Based on Machine Learning.

Governments use policy interventions to mitigate food safety risks. Despite its crucial role, empirical studies evaluating the effectiveness of China's food safety policy tools are scarce. Drawing on a dataset encompassing 11,236 food safety policy texts from 2005 to 2021 and the incidence of problematic food products in the Eastern, Central, and Western regions of China, this study employs Latent Dirichlet Allocation (LDA) and eXtreme Gradient Boosting (XGBoost) models to facilitate the classification of policy tools and forecast the effectiveness of policy combinations. The study reveals that (1) local governments have gradually become an important supplementary maker of food safety policies, and have issued an increasing number of policy tools year by year. (2) Mandatory policy tools are predominant in number and have the highest legal hierarchy and authority levels, followed successively by guiding policy and voluntary policy tools. (3) Mandatory policy tools demonstrated the most effective intervention results, followed successively by guiding policy and voluntary policy tools. (4) The forecast analysis reveals that combinations of policies within high-growth frameworks and those driven by mandatory regulations emerge as the most effective. Therefore, the balance of policy tools in terms of type, effectiveness, and quantity, as well as their applicability in different situations, should all be taken into account.

Study on Inerting Characteristics of Gas Coal by the Inerting Concentration and Ratio of an Inert Gas Mixture.

To study the effect of the inert gas mixture concentration and ratio on the spontaneous combustion reaction of gas coal, a combination of experimental research and theoretical analysis was used to study the pyrolysis and combustion kinetics characteristics of gas coal and further explore the influence of inert gas on the inerting characteristics of gas coal. Research has shown that during the entire heating reaction process of gas coal, the concentration of inert gases has little effect on the drying and desorption stages, but there is a significant lag phenomenon in the characteristic temperature points of active decomposition and degassing stages. Under the same concentration of mixed inert gases, the higher the relative percentage content of CO2, the more significant the change and the better the inhibitory effect. The higher the volume fraction of the inert gas, the higher the cross-temperature point. In the late stage of rapid heating of coal samples, when the volume fraction of inert gas is 40%, the rate of temperature rise increases rapidly. In a pure air environment, CO begins to be released at 80 °C, and when the temperature rises to 130 ∼ 140 °C, the concentration of CO begins to rapidly increase. Under inert conditions, the higher the relative percentage content of inert gas is, the higher the temperature point at which CO is generated. When the experimental conditions are a mixture of 30% N2 and 10% CO2 as inert gas, the optimal inerting effect has been achieved. The research results provide a theoretical basis for determining the optimal ratio of inert gas inerting concentrations to achieve fire prevention and extinguishing.

Historical evolution of basic characteristics, underlying causes, and management tools of food fraud in China: 1949-2022.

The emergence and development of food fraud are closely related to a country's economic system and social development. It has distinct characteristics in different historical stages, and an inherent historical logic links different historical stages. Following the thread of "what", "why", and "what to do", this study uses a broad perspective and comparative historical approach to examine the evolution of the basic characteristics, underlying causes, and management tools of food fraud in China at different historical stages over 70 years from 1949 to 2022. This study argues that the historical evolution of food fraud in China has characteristics unique to China as well as features similar to those in other countries. It provides a window for academics to understand the historical evolution of food fraud in China. It also provides valuable insights for other countries, especially developing countries, for objectively understanding the evolution of food fraud during their economic development process, and how to address it.

Vascular heterogeneity of tight junction Claudins guides organotropic metastasis.

Carcinomas are associated with metastasis to specific organs while sparing others. Breast cancer presents with lung metastasis but rarely kidney metastasis. Using this difference as an example, we queried the mechanism(s) behind the proclivity for organ-specific metastasis. We used spontaneous and implant models of metastatic mammary carcinoma coupled with inflammatory tissue fibrosis, single-cell sequencing analyses and functional studies to unravel the causal determinants of organ-specific metastasis. Here we show that lung metastasis is facilitated by angiopoietin 2 (Ang2)-mediated suppression of lung-specific endothelial tight junction protein Claudin 5, which is augmented by the inflammatory fibrotic microenvironment and prevented by anti-Ang2 blocking antibodies, while kidney metastasis is prevented by non-Ang2-responsive Claudins 2 and 10. Suppression of Claudins 2 and 10 was sufficient to induce the emergence of kidney metastasis. This study illustrates the influence of organ-specific vascular heterogeneity in determining organotropic metastasis, independent of cancer cell-intrinsic mechanisms.

Calibrating stochastic traffic simulation models for safety and operational measures based on vehicle conflict distributions obtained from aerial and traffic camera videos.

Proper calibration process is of considerable importance for traffic safety evaluations using simulation models. Allowing for a pure with and without comparison under identical circumstances that is not directly testable in the field, microsimulation-based approach has drawn considerable attention for the performance evaluation of emerging technologies, such as connected vehicle (CV) safety applications. Different from the traditional approaches to evaluate mobility impacts, safety evaluations of such applications demand the simulation models to be well calibrated to match real-world safety conditions. This paper proposes a novel calibration framework which combines traffic conflict techniques and multi-objective stochastic optimization so that the operational and safety measures can be calibrated simultaneously. The conflict distribution of different severity levels categorized by time-to-collision (TTC) is applied as the safety performance measure. Simultaneous perturbation stochastic approximation (SPSA) algorithm, which can efficiently approximate the gradient of the multi-objective stochastic loss function, is used for model parameters optimization that minimizes the total simulation error of both operational and safety performance measures. The proposed calibration methodology is implemented using an open-source software SUMO on a simulation network of the Flatbush Avenue corridor in Brooklyn, NY. 17 key parameters are calibrated using the SPSA algorithm and are compared with the real-world traffic conflicts extracted using vehicle trajectories from 14 h' high-resolution aerial and traffic surveillance videos. Representative days are identified to create variation envelopes for performance measures. Four acceptability criteria, including control for time-variant outliers and inliers, bounded dynamic absolute and system errors are adopted for results analysis. The results show that the calibrated parameters can significantly improve the performance of the simulation model to represent real-world safety conditions (i.e., traffic conflicts) as well as operational conditions. The case study also demonstrates the usefulness of aerial imagery and the applicability of the proposed model calibration framework, so the calibrated model can be used to evaluate the safety benefits of CV applications more accurately.

Phosphorylation of parkin by Parkinson disease-linked kinase PINK1 activates parkin E3 ligase function and NF-kappaB signaling.

Mutations in PTEN-induced putative kinase 1 (PINK1) or parkin cause autosomal recessive forms of Parkinson disease (PD), but how these mutations trigger neurodegeneration is poorly understood and the exact functional relationship between PINK1 and parkin remains unclear. Here, we report that PINK1 regulates the E3 ubiquitin-protein ligase function of parkin through direct phosphorylation. We find that phosphorylation of parkin by PINK1 activates parkin E3 ligase function for catalyzing K63-linked polyubiquitination and enhances parkin-mediated ubiquitin signaling through the IkappaB kinase/nuclear factor kappaB (NF-kappaB) pathway. Furthermore, the ability of PINK1 to promote parkin phosphorylation and activate parkin-mediated ubiquitin signaling is impaired by PD-linked pathogenic PINK1 mutations. Our findings support a direct link between PINK1-mediated phosphorylation and parkin-mediated ubiquitin signaling and implicate the deregulation of the PINK1/parkin/NF-kappaB neuroprotective signaling pathway in the pathogenesis of PD.

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust.

In order to master the combustion kinetic characteristics of semi-coking dust in the early pyrolysis stage of lignite combustion explosion, a vacuum tube furnace was used to prepare semi-coking dust with different pyrolysis degrees, and the experimental samples were studied by a synchronous differential thermal analyzer. By means of theoretical analysis, the reaction mechanism of lignite and semi-coking dust was revealed. The results show that when the final pyrolysis temperature rises to 920 °C, the percentage of volatile matter decreases by 94.6%. The reaction in this process also causes the original pores to be cross-linked and collapsed, and a large number of new pores are generated, and the original pore structure is significantly enlarged. With the increase of the final temperature of pyrolysis, the ignition temperature (T b) of the dust increased from 354 to 455 °C, the fastest reaction temperature (T c) increased from 399 to 495 °C, and the ember temperature (T d) increased from 558 to 658 °C. The maximum combustion rate decreased by 65.97%, and the average combustion rate decreased by 84.67%. The apparent activation energy increased by 4.7 times from 45.219 to 257.665 kJ/mol, and the combustion kinetics of semi-coke became worse. The thermal reaction of lignite and semi-coking dust conforms to the diffusion mechanism of the three-dimensional spherical symmetry model. The research results provide a new idea for discussing the mechanism of coal dust explosion and the development of explosion suppression technology.

N-terminal Domain of Amyloid-ß Impacts Fibrillation and Neurotoxicity.

Alzheimer's disease is characterized by the presence of distinct amyloid-ß peptide (Aß) assemblies with diverse sizes, shapes, and toxicity. However, the primary determinants of Aß aggregation and neurotoxicity remain unknown. Here, the N-terminal amino acid residues of Aß42 that distinguished between humans and rats were substituted. The effects of these modifications on the ability of Aß to aggregate and its neurotoxicity were investigated using biochemical, biophysical, and cellular techniques. The Aß-derived diffusible ligand, protofibrils, and fibrils formed by the N-terminal mutational peptides, including Aß42(R5G), Aß42(Y10F), and rat Aß42, were indistinguishable by conventional techniques such as size-exclusion chromatography, negative-staining transmission electron microscopy and silver staining, whereas the amyloid fibrillation detected by thioflavin T assay was greatly inhibited in vitro. Using circular dichroism spectroscopy, we discovered that both Aß42 and Aß42(Y10F) generated protofibrils and fibrils with a high proportion of parallel ß-sheet structures. Furthermore, protofibrils formed by other mutant Aß peptides and N-terminally shortened peptides were incapable of inducing neuronal death, with the exception of Aß42 and Aß42(Y10F). Our findings indicate that the N-terminus of Aß is important for its fibrillation and neurotoxicity.

Influence of Volatile Content on the Explosion Characteristics of Coal Dust.

To study the influence of different volatile contents on the explosion characteristics of coal dust, the volatile content in coal dust was controlled under different final temperatures of pyrolysis. The maximum explosion pressure, maximum pressure rising rate, and explosion index were used to characterize the pressure behavior, the pressure ratio to characterize the explosibility, and the minimum ignition temperature of the coal dust cloud to characterize the sensitive characteristics. A 20 L of nearly spherical coal dust explosion parameter measuring device and a dust cloud minimum ignition temperature measuring device were used to study the influence of the explosion characteristics of dust with different volatile contents prepared under different pyrolysis temperature conditions. The results showed that the volatile matter content in lignite dust has little effect on the maximum explosion pressure, with an average change rate of 5.435%. When the volatile content was reduced from 45.4 to 2.45%, the maximum explosion pressure rise rate dropped by 65.976%. The explosion index of the experimental sample was in the range of 0-1.6, with weak explosion characteristics; the lower the volatile content, the weaker the explosion intensity. When the volatile content was only 2.45%, the pressure ratio was still greater than 2, that is, the dust was still explosive. When the volatile content in lignite was reduced from 45.4 to 18.21%, the lowest ignition temperature of the dust cloud was consistently 490 °C. At this stage, the contents of H2, CO, CH4, CO2, and other precipitated dases were low. When the volatile content was reduced from 18.21 to 2.45%, the precipitated volatile gas increased rapidly, the remaining precipitated gas content decreased, and the dust could not be easily ignited. The experimental results lay the foundation for studying the influence mechanism of volatile matter in coal dust on the explosion characteristics.

Mechanism of neuroprotective function of taurine.

Taurine has potent protective function against glutamate-induced neuronal injury presumably through its function in regulation of intracellular free calcium level, [Ca2+]i. In this communication, we report that taurine exerts its protective function through one or more of the following mechanisms: 1. Inhibition of glutamate-induced calcium influx through L-, N- and P/Q-type voltage-gated calcium channels and NMDA receptor calcium channel; 2. Attenuation of glutamate-induced membrane depolarization; 3. Prevention of glutamate-induced apoptosis via preventing glutamate-mediated down-regulation of Bcl-2; 4. Prevention of cleavage of Bcl-2 by calpain. This action of taurine is due to its inhibition on glutamate induced calpain activation. Based on these observations, we propose that taurine protects neurons against glutamate-induced neurotoxicity in part, by preventing glutamate-induced membrane depolarization, elevation of [Ca2+]i, activation of calpain, reduction of Bcl-2 and apoptosis.

Role of mu-calpain in proteolytic cleavage of brain L-glutamic acid decarboxylase.

Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme for gamma-aminobutyric acid (GABA) biosynthesis. Previously, we reported the presence of truncated forms of GAD in vivo and in vitro. In addition, an unidentified endogenous protease responsible for proteolytic cleavage of full-length GAD (fGAD) to its truncated form (tGAD) was also observed. In this communication, we report that mu-calpain is a good candidate for conversion of fGAD(67) to tGAD(67). This conclusion is based on the following observations: 1. purified recombinant GAD(67) is cleaved by mu-calpain at specific sites; 2. in brain synaptosomal preparation, GAD(67) is cleaved to its truncated form by an endogenous protease which is inhibited by specific calpain inhibitors; 3. in mu-calpain knockout mice, the level of tGAD in the brain is greatly reduced compared with the wild type; 4. when mu-calpain gene is silenced by siRNA, the level of tGAD is also markedly reduced compared to the control group; and 5. mu-calpain is activated by neuronal stimulation and Ca(2+)-influx. The physiological significance of calpain in regulation of GABA synthesis and GABAergic neurotransmission is also discussed.

Parkin Protects Against Misfolded SOD1 Toxicity by Promoting Its Aggresome Formation and Autophagic Clearance.

Mutations in Cu/Zn superoxide dismutase (SOD1) cause autosomal dominant amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease with no effective treatment. Despite ample evidence indicating involvement of mutation-induced SOD1 protein misfolding and aggregation in ALS pathogenesis, the molecular mechanisms that control cellular management of misfolded, aggregation-prone SOD1 mutant proteins remain unclear. Here, we report that parkin, an E3 ubiquitin-protein ligase which is linked to Parkinson's disease, is a novel regulator of cellular defense against toxicity induced by ALS-associated SOD1 mutant proteins. We find that parkin mediates K63-linked polyubiquitination of SOD1 mutants in cooperation with the UbcH13/Uev1a E2 enzyme and promotes degradation of these misfolded SOD1 proteins by the autophagy-lysosome system. In response to strong proteotoxic stress associated with proteasome impairment, parkin promotes sequestration of misfolded and aggregated SOD1 proteins to form perinuclear aggresomes, regulates positioning of lysosomes around misfolded SOD1 aggresomes, and facilitates aggresome clearance by autophagy. Our findings reveal parkin-mediated cytoprotective mechanisms against misfolded SOD1 toxicity and suggest that enhancing parkin-mediated cytoprotection may provide a novel therapeutic strategy for treating ALS.

Preparation of hydrophilic luffa sponges and their water absorption performance.

Hydrophilic luffa sponges are prepared by grafting polymerization of acrylamide (AM) on luffa cylindrica and subsequent partial hydrolysis under alkaline conditions. Attenuated total reflection infrared spectroscopy is used to verify the composition of the grafted (luffa-g-PAM) and hydrolyzed (luffa-g-(PAM-co-PAANa)) samples. Alkalization conditions, including aqueous NaOH concentrations, alkalization temperature, and time, are studied extensively. Optimized conditions are then obtained. The grafting percentage (GP) of polyacrylamide increases with the feed ratios of [AM]/[OH] and [Ce]/[OH], reaction temperature, and time. Furthermore, the GP can reach up to 160%. Pristine, alkalized, grafted, and hydrolyzed luffa sponges show rapid absorption kinetics, and the pseudo second-order rate equation is applied to describe their kinetic procedure. Reaction conditions, such as [AM]/[OH], [Ce]/[OH], reaction temperature and time, influence the water absorption capacities of grafted and hydrolyzed samples. The hydrolyzed luffa sponges particularly exhibit high water absorption capacities of 75gg(-1). The absorption mechanism is also discussed.

Molecular cloning, expression, purification, and characterization of shorter forms of human glutamic decarboxylase 67 in an E. coli expression system.

Previously, we reported the presence of truncated form of human brain l-glutamic decarboxylase 65 (tGAD65) in vivo as well as in vitro and found that tGAD65 was more active than the full-length GAD65 (Wei et al., J. Biomed. Sci., 10: 617-624, 2003). Here, we report the presence of two shorter forms of hGAD67, namely, hGAD67 (Delta1-70) and hGAD(67) (Delta1-90), referring to a deletion of 1-70 and 1-90 amino acids from the N-terminal, respectively. The molecular masses of hGAD67 (Delta1-70) and hGAD67 (Delta1-90) were found to be 59 kDa and 57 kDa, respectively. Both shorter forms were cloned, expressed, and characterized. In contrast to hGAD65, the shorter forms of hGAD67 were much less active than the full-length due to decrease in affinity of PLP towards the shorter enzymes. Both the full-length and one of the shorter forms of GAD67 were detected in porcine brain extract. Furthermore, the full-length GAD67 could be converted to both shorter forms by crude brain extract, suggesting that an endogenous protease may be present in the brain, which is responsible for the conversion. The cleavage of GAD67 seems to be Ca+(2)-dependent. The model for the conversion of GAD from full-length GAD to shorter forms of GAD and its physiological implications was proposed.

Mode of action of taurine as a neuroprotector.

Previously, it has been shown that taurine exerts its protective function against glutamate-induced neuronal excitotoxicity through its action in reducing glutamate-induced elevation of intracellular free calcium, [Ca2+]i. Here, we report the mechanism underlying the effect of taurine in reducing [Ca2+]i. We found that taurine inhibited glutamate-induced calcium influx through L-, P/Q-, N-type voltage-gated calcium channels (VGCCs) and NMDA receptor calcium channel. Surprisingly, taurine had no effect on calcium influx through NMDA receptor calcium channel when cultured neurons were treated with NMDA in Mg2+-free medium. Since taurine was found to prevent glutamate-induced membrane depolarization, we propose that taurine protects neurons against glutamate excitotoxicity by preventing glutamate-induced membrane depolarization, probably through its effect in opening of chloride channels and, therefore, preventing the glutamate-induced increase in calcium influx and other downstream events.

H8-BINOL chiral imidodiphosphoric acid catalyzed highly enantioselective aza-Friedel-Crafts reactions of pyrroles and enamides/imines.

The first enantioselective aza-Friedel-Crafts reaction between pyrroles and enamides has been achieved by using a novel H8-BINOL-type imidodiphosphoric acid catalyst. This methodology was also applied to the highly enantioselective aza-Friedel-Crafts reaction between pyrroles and imines. The catalyst loadings in these two reactions are low (0.3-2 mol%). Both processes are amenable to gram scales.