Acetylation changes tau interactome to degrade tau in Alzheimer’s disease animal and organoid models

Alzheimer's disease (AD) is an age‐related neurodegenerative disease. The most common pathological hallmarks are amyloid plaques and neurofibrillary tangles in the brain. In the brains of patients with AD, pathological tau is abnormally accumulated causing neuronal loss, synaptic dysfunction, and cognitive decline. We found a histone deacetylase 6 (HDAC6) inhibitor, CKD‐504, changed the tau interactome dramatically to degrade pathological tau not only in AD animal model (ADLP^APT) brains containing both amyloid plaques and neurofibrillary tangles but also in AD patient‐derived brain organoids. Acetylated tau recruited chaperone proteins such as Hsp40, Hsp70, and Hsp110, and this complex bound to novel tau E3 ligases including UBE2O and RNF14. This complex degraded pathological tau through proteasomal pathway. We also identified the responsible acetylation sites on tau. These dramatic tau‐interactome changes may result in tau degradation, leading to the recovery of synaptic pathology and cognitive decline in the ADLP^APT mice.     

蛋白质序列的六维表示与相似性分析

给出了蛋白质序列的一种六维表示方法,根据这种表示方法有3种不同表示形式,利用这3种形式来构造距离矩阵的信息熵,然后通过信息熵向量的欧式距离、夹角来比较序列之间的相似性。     

An integrated approach for thermal stabilization of a mesophilic adenylate kinase

Thermally stable proteins are desirable for research and industrial purposes, but redesigning proteins for higher thermal stability can be challenging. A number of different techniques have been used to improve the thermal stability of proteins, but the extents of stability enhancement were sometimes unpredictable and not significant. Here, we systematically tested the effects of multiple stabilization techniques including a bioinformatic method and structure‐guided mutagenesis on a single protein, thereby providing an integrated approach to protein thermal stabilization. Using a mesophilic adenylate kinase (AK) as a model, we identified stabilizing mutations based on various stabilization techniques, and generated a series of AK variants by introducing mutations both individually and collectively. The redesigned proteins displayed a range of increased thermal stabilities, the most stable of which was comparable to a naturally evolved thermophilic homologue with more than a 25° increase in its thermal denaturation midpoint. We also solved crystal structures of three representative variants including the most stable variant, to confirm the structural basis for their increased stabilities. These results provide a unique opportunity for systematically analyzing the effectiveness and additivity of various stabilization mechanisms, and they represent a useful approach for improving protein stability by integrating the reduction of local structural entropy and the optimization of global noncovalent interactions such as hydrophobic contact and ion pairs. Proteins 2014; 82:1947–1959. © 2014 Wiley Periodicals, Inc.     

The WEE1 regulators CPEB1 and miR-15b switch from inhibitor to activators at G2/M

MicroRNAs (miRNAs) in the AGO-containing RISC complex control messenger RNA (mRNA) translation by binding to mRNA 3′ untranslated region (3′UTR). The relationship between miRNAs and other regulatory factors that also bind to mRNA 3′UTR, such as CPEB1 (cytoplasmic polyadenylation element-binding protein), remains elusive. We found that both CPEB1 and miR-15b control the expression of WEE1, a key mammalian cell cycle regulator. Together, they repress WEE1 protein expression during G1 and S-phase. Interestingly, the 2 factors lose their inhibitory activity at the G2/M transition, at the time of the cell cycle when WEE1 expression is maximal, and, moreover, rather activate WEE1 translation in a synergistic manner. Our data show that translational regulation by RISC and CPEB1 is essential in cell cycle control and, most importantly, is coordinated, and can be switched from inhibition to activation during the cell cycle.     

New protein isoforms identified within Arabidopsis thaliana seed oil bodies combining chymotrypsin/trypsin digestion and peptide fragmentation analysis

Plant seed oil bodies, subcellular lipoprotein inclusions providing storage reserves, are composed of a neutral lipid core surrounded by a phospholipid monolayer with several integrated proteins that play a significant role in stabilization of the particles and probably also in lipid mobilization. Oil bodies' proteins are generally very hydrophobic, due to the long uncharged sequences anchoring them into the lipid core, which makes them extremely difficult to handle and to digest successfully. Although oil bodies have been intensively studied during last decades, not all their proteins have been identified yet. To overcome the problems connected with their identification, a method based on SDS-PAGE, in-gel digestion and LC-MS/MS analysis was used. Digestion was carried out with trypsin and chymotrypsin, single or in combination, which increased significantly the number of identified peptides, namely the hydrophobic ones. Thanks to this methodology it was possible to achieve an extensive coverage of proteins studied, to analyze their N-terminal modifications and moreover, to detect four new oil bodies' protein isoforms, which demonstrates the complexity of oil bodies' protein composition.     

An empirical EEG analysis in brain death diagnosis for adults

Electroencephalogram (EEG) is often used in the confirmatory test for brain death diagnosis in clinical practice. Because EEG recording and monitoring is relatively safe for the patients in deep coma, it is believed to be valuable for either reducing the risk of brain death diagnosis (while comparing other tests such as the apnea) or preventing mistaken diagnosis. The objective of this paper is to study several statistical methods for quantitative EEG analysis in order to help bedside or ambulatory monitoring or diagnosis. We apply signal processing and quantitative statistical analysis for the EEG recordings of 32 adult patients. For EEG signal processing, independent component analysis (ICA) was applied to separate the independent source components, followed by Fourier and time-frequency analysis. For quantitative EEG analysis, we apply several statistical complexity measures to the EEG signals and evaluate the differences between two groups of patients: the subjects in deep coma, and the subjects who were categorized as brain death. We report statistically significant differences of quantitative statistics with real-life EEG recordings in such a clinical study, and we also present interpretation and discussions on the preliminary experimental results.

细胞寒害的热力学熵理论(Ⅱ)──超熵产生作为寒害稳定性判据的理论研究

本文从物质和能量交换的角度,运用非平衡态热力学超熵产生理论,分析了寒害定态的稳定性,并建立了超熵产生判据．理论分析所得的结论与实验结果基本相符．     

应用小波熵分析大鼠脑电信号的动态变化特性

应用小波熵（一种新的信号复杂度测量方法）分析大鼠在不同生理状态下脑电复杂度的动态时变特性。采用慢性埋植电极记录自由活动大鼠的皮层EEG,使用多分辨率小波变换将EEG信号分解为δ、θ、α和β四个分量,求得随时间变化的小波熵。结果表明：在清醒、慢波睡眠和快动眼睡眠三种生理状态下,EEG的小波熵之间存在显著差别,并且在不同时期其值与各个分解分量之间具有不同的关系,其中,慢波睡眠期小波熵还具有较明显的变化节律,反映了EEG微状态中慢波和纺锤波的互补性。由此可见,小波熵既能区别长时间段EEG复杂度之间的差别,又能反映EEG微状态的快速变化特性。     

The RNA binding protein Musashi1 regulates apoptosis,gene expression and stress granule formation in urothelial carcinoma cells

The RNA‐binding protein Musashi1 (MSI1) is a marker of progenitor cells in the nervous system functioning as a translational repressor. We detected MSI1 mRNA in several bladder carcinoma cell lines, but not in cultured normal uroepithelial cells, whereas the paralogous MSI2 gene was broadly expressed. Knockdown of MSI1 expression by siRNA induced apoptosis and a severe decline in cell numbers in 5637 bladder carcinoma cells. Microarray analysis of gene expression changes after MSI1 knockdown significantly up‐regulated 735 genes, but down‐regulated only 31. Up‐regulated mRNAs contained a highly significantly greater number and density of Musashi binding sites. Therefore, a much larger set of mRNAs may be regulated by Musashi1, which may affect not only their translation, but also their turnover. The study confirmed p21^CIP1 and Numb proteins as targets of Musashi1, suggesting additionally p27^KIP1 in cell‐cycle regulation and Jagged‐1 in Notch signalling. A significant number of up‐regulated genes encoded components of stress granules (SGs), an organelle involved in translational regulation and mRNA turnover, and impacting on apoptosis. Accordingly, heat shock induced SG formation was augmented by Musashi1 down‐regulation. Our data show that ectopic MSI1 expression may contribute to tumorigenesis in selected bladder cancers through multiple mechanisms and reveal a previously unrecognized function of Musashi1 in the regulation of SG formation.