The different dissipation behavior of chiral pesticide paclobutrazol in the brine during Chinese cabbage pickling process

Paclobutrazol (PBZ) is a kind of chiral pesticide, which is a plant growth regulator and has fungicidal activity. Because of the steric‐hindrance effect, there are two enantiomers (2S, 3S; 2R, 3R) in the production. This research studied on the dissipation behavior of chiral pesticide PBZ in the brine during the Chinese cabbage pickled process by phase column‐high performance liquid chromatography (HPLC). The result demonstrated the PBZ enantiomers had the different dissipation in the brine. The study on the behavior of chiral pesticide PBZ in food may provide more sufficient data and information for understanding the potential risk in food and evaluating the environmental pollution at the enantiomer level.     

Mimotopes selected with a neutralizing antibody against urease B from <Emphasis Type="Italic">Helicobacter pylori</Emphasis>induce enzyme inhibitory antibodies in mice upon vaccination

Background  

Urease B is an important virulence factor that is required for Helicobacter pylori to colonise the gastric mucosa. Mouse monoclonal antibodies (mAbs) that inhibit urease B enzymatic activity will be useful as vaccines for the prevention and treatment of H. pylori infection. Here, we produced murine mAbs against urease B that neutralize the enzyme's activity. We mapped their epitopes by phage display libraries and investigated the immunogenicity of the selected mimotopes in vivo.     

Crystal structure of the C2 domain of class II phosphatidylinositide 3-kinase C2alpha

Phosphatidylinositide (PtdIns) 3-kinase catalyzes the addition of a phosphate group to the 3'-position of phosphatidyl inositol. Accumulated evidence shows that PtdIns 3-kinase can provide a critical signal for cell proliferation, cell survival, membrane trafficking, glucose transport, and membrane ruffling. Mammalian PtdIns 3-kinases are divided into three classes based on structure and substrate specificity. A unique characteristic of class II PtdIns 3-kinases is the presence of both a phox homolog domain and a C2 domain at the C terminus. The biological function of the C2 domain of the class II PtdIns 3-kinases remains to be determined. We have determined the crystal structure of the mCPK-C2 domain, which is the first three-dimensional structural model of a C2 domain of class II PtdIns 3-kinases. Structural studies reveal that the mCPK-C2 domain has a typical anti-parallel beta-sandwich fold. Scrutiny of the surface of this C2 domain has identified three small, shallow sulfate-binding sites. On the basis of the structural features of these sulfate-binding sites, we have studied the lipid binding properties of the mCPK-C2 domain by site-directed mutagenesis. Our results show that this C2 domain binds specifically to PtdIns(3,4)P(2) and PtdIns(4,5)P(2) and that three lysine residues at SBS I site, Lys-1420, Lys-1432, and Lys-1434, are responsible for the phospholipid binding affinity.     

Effect of the Platelet-Activating Factor Antagonist BN 50739 and Its Diluents on Mitochondrial Respiration and Membrane Lipids During and Following Cerebral Ischemia

Abstract: Recent evidence suggests that platelet-activating factor plays a role in ischemia-induced neural injury. The Pulsinelli-Brierley four-vessel occlusion model was used to study the effect of a synthetic platelet-activating factor antagonist, BN 50739, and its solvents, either dimethyl sulfoxide or hydroxypropyl-β-cyclodextrin, on cerebral ischemia-reperfusion. Rats were subjected to either 30 min of ischemia or 30 min of ischemia followed by 60 min of recirculation. Changes in the brain mitochondrial free fatty acid pool size, fatty acyl composition of phospholipids, and respiratory function were monitored. When the BN 50739 (2 mg of BN 50739/kg of body weight i.v.) was administered at the onset of recirculation, it significantly reversed the ischemia-induced accumulation of mitochondrial free fatty acids and loss of polyunsaturated fatty acyl chains from phosphatidylcholine and phosphatidylethanolamine while simultaneously improving mitochondrial respiration. Dimethyl sulfoxide alone decreased the mitochondrial level of malonyldialdehyde and total free fatty acid pool size, but there was no improvement in mitochondrial respiration. Hydroxypropyl-β-cyclodextrin was reported to be pharmacologically inactive and capable of dissolving BN 50739. However, hydroxypropyl-β-cyclodextrin alone also caused a significant increase in content of cerebral mitochondrial membrane free fatty acids and hydrolysis of phosphatidylcholine in normoxic control animals. The overall effect of BN 50739 on mitochondrial structure and energy metabolism supports the hypothesis that platelet-activating factor may play a key role in ischemia-induced cerebral injury.     

GSK3β-mediated tau hyperphosphorylation triggers diabetic retinal neurodegeneration by disrupting synaptic and mitochondrial functions

Background

Although diabetic retinopathy (DR) has long been considered as a microvascular disorder, mounting evidence suggests that diabetic retinal neurodegeneration, in particular synaptic loss and dysfunction of retinal ganglion cells (RGCs) may precede retinal microvascular changes. Key molecules involved in this process remain poorly defined. The microtubule-associated protein tau is a critical mediator of neurotoxicity in Alzheimer’s disease (AD) and other neurodegenerative diseases. However, the effect of tau, if any, in the context of diabetes-induced retinal neurodegeneration has yet to be ascertained. Here, we investigate the changes and putative roles of endogeneous tau in diabetic retinal neurodegeneration.

Methods

To this aim, we combine clinically used electrophysiological techniques, i.e. pattern electroretinogram and visual evoked potential, and molecular analyses in a well characterized high-fat diet (HFD)-induced mouse diabetes model in vivo and primary retinal ganglion cells (RGCs) in vitro.

Results

We demonstrate for the first time that tau hyperphosphorylation via GSK3β activation causes vision deficits and synapse loss of RGCs in HFD-induced DR, which precedes retinal microvasculopathy and RGCs apoptosis. Moreover, intravitreal administration of an siRNA targeting to tau or a specific inhibitor of GSK3β reverses synapse loss and restores visual function of RGCs by attenuating tau hyperphosphorylation within a certain time frame of DR. The cellular mechanisms by which hyperphosphorylated tau induces synapse loss of RGCs upon glucolipotoxicity include i) destabilizing microtubule tracks and impairing microtubule-dependent synaptic targeting of cargoes such as mRNA and mitochondria; ii) disrupting synaptic energy production through mitochondria in a GSK3β-dependent manner.

Conclusions

Our study proposes mild retinal tauopathy as a new pathophysiological model for DR and tau as a novel therapeutic target to counter diabetic RGCs neurodegeneration occurring before retinal vasculature abnormalities.

     

BCL10 regulates RNF8/RNF168-mediated ubiquitination in the DNA damage response

Timely and proper cellular response to DNA damage is essential for maintenance of genome stability and integrity. B-cell lymphoma/leukemia 10 (BCL10) facilitates ubiquitination of NEMO in the cytosol, activating NFκB signaling. Translocation and/or point mutations of BCL10 associate with mucosa-associated lymphoid tissue lymphomas and other malignancies. However, the mechanisms by which the resulting aberrant expression of BCL10 leads to cellular oncogenesis are poorly understood. In this report, we found that BCL10 in the nucleus is enriched at the DNA damage sites in an ATM- and RNF8-dependent manner. ATM-dependent phosphorylation of BCL10 promotes its interaction with and presentation of UBC13 to RNF8, and RNF8-mediated ubiquitination of BCL10 enhances binding of BCL10 and UBC13 to RNF168. This allows mono-ubiquitination on H2AX by RNF168 and further poly-ubiquitination by the RNF8/RNF168-containing complex. Depletion of BCL10 compromised homology recombination-mediated DNA double-strand break (DSB) repair because of insufficient recruitment of BRCA1, RAD51, and the ubiquitinated DNA damage response factors. Taken together, our results demonstrate a novel function of BCL10 in delivering UBC13 to RNF8/RNF168 to regulate ubiquitination-mediated DSB signaling and repair.     

Protection of Retina by αB Crystallin in Sodium Iodate Induced Retinal Degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness in the developed world. The retinal pigment epithelium (RPE) is a critical site of pathology in AMD and αB crystallin expression is increased in RPE and associated drusen in AMD. The purpose of this study was to investigate the role of αB crystallin in sodium iodate (NaIO₃)-induced retinal degeneration, a model of AMD in which the primary site of pathology is the RPE. Dose dependent effects of intravenous NaIO₃ (20-70 mg/kg) on development of retinal degeneration (fundus photography) and RPE and retinal neuronal loss (histology) were determined in wild type and αB crystallin knockout mice. Absence of αB crystallin augmented retinal degeneration in low dose (20 mg/kg) NaIO₃-treated mice and increased retinal cell apoptosis which was mainly localized to the RPE layer. Generation of reactive oxygen species (ROS) was observed with NaIO₃ in mouse and human RPE which increased further after αB crystallin knockout or siRNA knockdown, respectively. NaIO₃ upregulated AKT phosphorylation and peroxisome proliferator–activator receptor–γ (PPAR_γ) which was suppressed after αB crystallin siRNA knockdown. Further, PPAR_γ ligand inhibited NaIO₃-induced ROS generation. Our data suggest that αB crystallin plays a critical role in protection of NaIO₃-induced oxidative stress and retinal degeneration in part through upregulation of AKT phosphorylation and PPAR_γ expression.