Protamine‐induced condensation of peptide nanofilaments into twisted bundles with controlled helical geometry

Chiral self‐assembly of peptides is of fundamental interest in the field of biology and material science. Protamine, an alkaline biomacromolecule which is ubiquitous in fish and mammalian, plays crucial roles in directing the helical twisting of DNA. Inspired by this, we reported a bioinspired pathway to direct the hierarchical chiral self‐assembly of a short synthetic dipeptide. The peptide could self‐assemble into negatively charged chiral micelles in water that spontaneously formed a nematic liquid crystalline phase. By incorporation with protamine, the micelles condensed with the protamine into large helical bundles with precisely controlled diameter. Furthermore, to simulate the intracellular environments, we investigated macromolecular crowding on the coassembly of peptide and protamine, which leads to the formation of much thinner helical structures. The results highlight the roles of highly charged biomacromolecules and macromolecular crowding on peptide self‐assembly, which are beneficial for the practical applications of self‐assembling peptides in biomedicine and sensing.     

Higher Matrix Stiffness Upregulates Osteopontin Expression in Hepatocellular Carcinoma Cells Mediated by Integrin β1/GSK3β/β-Catenin Signaling Pathway

Increased stromal stiffness is associated with hepatocellular carcinoma (HCC) development and progression. However, the molecular mechanism by which matrix stiffness stimuli modulate HCC progress is largely unknown. In this study, we explored whether matrix stiffness-mediated effects on osteopontin (OPN) expression occur in HCC cells. We used a previously reported in vitro culture system with tunable matrix stiffness and found that OPN expression was remarkably upregulated in HCC cells with increasing matrix stiffness. Furthermore, the phosphorylation level of GSK3β and the expression of nuclear β-catenin were also elevated, indicating that GSK3β/β-catenin pathway might be involved in OPN regulation. Knock-down analysis of integrin β1 showed that OPN expression and p-GSK3β level were downregulated in HCC cells grown on high stiffness substrate compared with controls. Simultaneously, inhibition of GSK-3β led to accumulation of β-catenin in the cytoplasm and its enhanced nuclear translocation, further triggered the rescue of OPN expression, suggesting that the integrin β1/GSK-3β/β-catenin pathway is specifically activated for matrix stiffness-mediated OPN upregulation in HCC cells. Tissue microarray analysis confirmed that OPN expression was positively correlated with the expression of LOX and COL1. Taken together, high matrix stiffness upregulated OPN expression in HCC cells via the integrin β1/GSK-3β/β-catenin signaling pathway. It highlights a new insight into a pathway involving physical mechanical signal and biochemical signal molecules which contributes to OPN expression in HCC cells.     

我国害鼠不育控制研究进展

害鼠给人类带来巨大的经济损失,导致严重的生态问题。人们采用各种方法防治鼠害,其中不育控制是一种新的方法。不育控制即通过某种手段使雄性或和雌性绝育,或阻碍胚胎着床,甚至阻断幼体生长,以降低生育率。不育控制的概念最早在20世纪60年代提出,近年来,我国在利用不育技术控制害鼠方面做了大量研究,总结了国内该领域研究的部分结果。在实验室测试了多种不育剂。被测试的不育剂对相应的鼠类几乎都有不育作用;一些不育剂会影响鼠类的行为,这会减弱竞争性繁殖干扰的作用;一些不育剂在达到一定剂量后有致死作用,不育和灭杀的双重作用会产生更好的控制效果;还观察到不育个体的复孕现象,这会减弱控制效果;关于不育剂安全性的研究发现更昔洛韦和M001雄性不育灭鼠剂对家鸽没有任何毒性作用。大量野外实验证实不育剂对害鼠大都有较好的控制效果,实际控制中,控制面积不宜太小。利用数学模型所作的理论分析表明不育控制有不比灭杀控制差的效果;在决定种群是否灭绝上,不育率、灭杀率、选择性收获率等的作用是相同的。根据研究的实际情况,本文提出了一些今后研究中应注意的问题。无论在实验室还是野外,除了种群动态外,还要记录更详细的数据,以期对不育控制有更详细的了解。要加大不育剂对非靶向动物和环境影响的研究。在不育控制这种干扰下,害鼠种群的变化必然导致与其相关的种群也作出相应的变化,这一方面的研究需要进行。每种控制方式都有自己的特点,多种控制方法联合使用会达到更理想的效果。竞争性繁殖干扰现象是存在的,它使种群规模更小,在数学模型中,应体现出这一因素。     

Parthenolide regulates oxidative stress-induced mitophagy and suppresses apoptosis through p53 signaling pathway in C2C12 myoblasts

Muscle redox disturbances and oxidative stress have emerged as a common pathogenetic mechanism and potential therapeutic intervention in some muscle diseases. Parthenolide (PTL), a sesquiterpene lactone found in large amounts in the leaves of feverfew, possesses anti-inflammatory, anti-migraine, and anticancer properties. Although PTL was reported to alleviate cancer cachexia and improve skeletal muscle characteristics in a cancer cachexia model, its actions on oxidative stress-induced damage in C2C12 myoblasts have not been reported and the regulatory mechanisms have not yet been defined. In our study, PTL attenuated H₂O₂-induced growth inhibition and morphological changes. Furthermore, PTL exhibited scavenging activity against reactive oxygen species and protected C2C12 cells from apoptosis in response to H₂O₂. Meanwhile, PTL suppressed collapse of the mitochondrial membrane potential, thereby contributing to normalizing H₂O₂-induced autophagy flux and mitophagy, correlating with inhibiting degradation of mitochondrial marker protein TIM23, the increase in LC3-II expression and the reduction of mitochondria DNA. Besides its protective effect on mitochondria, PTL also prevented H₂O₂-induced lysosomes damage in C2C12 cells. In addition, the phosphorylation of p53, cathepsin B, and Bax/Bcl-2 protein levels, and the translocation of Bax from the cytosol to mitochondria induced by H₂O₂ in C2C12 cells was significantly reduced by PTL. In conclusion, PTL modulates oxidative stress-induced mitophagy and protects C2C12 myoblasts against apoptosis, suggesting a potential protective effect against oxidative stress-associated skeletal muscle diseases.     

β-半乳糖苷酶酶学性质及其在低聚半乳糖合成中的应用

研究乳酸克鲁维酵母所产β-半乳糖苷酶的酶学性质及低聚半乳糖(galactooligosaccharides,GOS)的酶法合成条件。利用高效液相色谱法进行检测,以GOS(聚合度n3)生成量为指标,考察温度、pH、金属离子种类和浓度对酶活性的影响,以及K+存在时,底物浓度、反应时间、加酶量对乳糖转化率及GOS生成浓度的影响。结果表明:一价离子对β-半乳糖苷酶转糖苷活性具有促进作用,其中K+、NH+4对水解活性同样起促进作用,而Na+起抑制作用;制备低聚半乳糖的最佳工艺条件为37℃、pH8.0、K+0.08mol/L、初始乳糖质量浓度500g/L、反应时间5h、加酶量10μL/g乳糖,此条件下低聚半乳糖的生成质量浓度达到94.74g/L。     

Photo-induced inhibition of insulin amyloid fibrillation on online laser measurement

Shigella flexneri serotype 2a is a major public health concern in the developing and under-developed countries which contributes to shigellosis endemic and mortality. Thus, there is an urgent need for a rapid diagnostic test for effective therapy and disease management. Previous study showed that a ∼35 kDa antigenic protein from S. flexneri is a potential biomarker. We therefore modelled the three-dimensional structure of the antigen to probe its functionality which could aid in the development of an antigen-based diagnostic. Results showed that the antigen is a transmembrane protein consists of OmpA and OmpA-like domains. The OmpA domain is a beta-barrel embedded in the outer membrane with four surface-exposed extracellular loops. The OmpA-like domain is linked to the OmpA domain with a 17 amino acids linker and located in the periplasmic. Docking of peptidoglycan into the groove of OmpA-like domain might help in catalyzing the bacterial cell wall formation. Both domains are expected to be involved in the virulence, structural stability, pathogenesis and survival of Shigella thus made the 35 kDa protein a suitable shigellosis diagnostic biomarker. This structural elucidation will also enable a better identification of the epitope regions for the development of specific binders to the 35 kDa antigen.     

Photo-induced inhibition of insulin amyloid fibrillation on online laser measurement

Protein aggregation and amyloid fibrillation can lead to several serious diseases and protein drugs ineffectiveness; thus, the detection and inhibition of these processes have been of great interest. In the present study, the inhibition of insulin amyloid fibrillation by laser irradiation was investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM), far-UV circular dichroism (far-UV CD), and thioflavin T (ThT) fluorescence. During heat-induced aggregation, the size distribution of two insulin solutions obtained by online and offline dynamic light scattering were different. The laser-on insulin in the presence of 0.1 M NaCl exhibited fewer fibrils than the laser-off insulin, whereas no insulin fibril under laser irradiation was observed in the absence of 0.1 M NaCl for 45 h incubation. Moreover, our CD results showed that the laser-irradiated insulin solution maintained mainly an α-helical conformation, but the laser-off insulin solution formed bulk fibrils followed by a significant increase in β-sheet content for 106 h incubation. These findings provide an inhibition method for insulin amyloid fibrillation using the laser irradiation and demonstrate that the online long-time laser measurements should be carefully used in the study of amyloid proteins because they may change the original results.