d-Ribose glycates β(2)-microglobulin to form aggregates with high cytotoxicity through a ROS-mediated pathway

β(2)-Microglobulin (β(2)M) modified with advanced glycation end products (AGEs) is a major component of the amyloid deposits in hemodialysis-associated amyloidosis (HAA). However, the effect of glycation on the misfolding and aggregation of β(2)M has not been studied so far. Here we examine the molecular mechanism of aggregate formation of HAA-related ribosylated β(2)M in vitro. We find that the glycating agent d-ribose interacts with human β(2)M to generate AGEs that form aggregates in a time-dependent manner. Ribosylated β(2)M molecules are highly oligomerized compared with unglycated β(2)M, and have granular morphology. Furthermore, such ribosylated β(2)M aggregates show significant cytotoxicity to both human SH-SY5Y neuroblastoma and human foreskin fibroblast FS2 cells and induce intracellular reactive oxygen species (ROS). Presence of the antioxidant N-acetylcysteine (1.0mM) attenuated intracellular ROS and prevented cell death induction in both SH-SY5Y and FS2 cells, indicating that the cytotoxicity of ribosylated β(2)M aggregates depends on a ROS-mediated pathway in both cell lines. In other words, d-ribose reacts with β(2)M and induces the ribosylated protein to form granular aggregates with high cytotoxicity through a ROS-mediated pathway. These findings suggest that ribosylated β(2)M aggregates could contribute to the dysfunction and death of cells and could play an important role in the pathogenesis of β(2)M-associated diseases such as HAA.     

鼎湖山季风常绿阔叶林小气候特征分析

阐述了鼎湖山季风常绿阔叶林小气候特征与空旷地的差异 ,并分析了这些差异产生的原因。结果表明 :季风常绿阔叶林冠层顶部的太阳总辐射量年平均为 3488.8MJ·m- 2 ,由辐射强度和辐射总量计算出的反射率分别为 1 0 .5%、1 1 .4% ,年平均气温为 1 9.9℃ ,此 3项都比空旷地低 ,而年平均相对湿度高于空旷地 ,其值为 87% ;季风常绿阔叶林年蒸散力为987.50 mm,湿润指数为 0 .96;季风常绿阔叶林土壤表层温度日变化不及空旷地显著 ;无论是季风常绿阔叶林 ,还是空旷地 ,土壤温度在春、夏季节自上而下逐步降低 ,在秋、冬季节自上而下逐步升高。     

R-ISSR as a new tool for genomic fingerprinting, mapping, and gene tagging

In the present study we propose and test the concept of R-ISSR, a new tool for genomic fingerprinting, mapping, and gene tagging. The concept is based on the fact that primers for inter-simple sequence repeat (ISSR) and random-amplified polymorphic DNA (RAPD) analysis elicit different genomic information, and the combined use of these 2 kinds of primers in the same polymerase chain reaction (PCR) reactions might reveal new genomic loci that could not be detected with either technique alone. The feasibility of this tool was first electronically simulated with sequence analysis software andArabidopsis chromosome sequence. Next, different combinations of ISSR and RAPD primers were applied in real PCR reactions to detect new genomic loci in 2 maize lines (Q319 and 1145). Sequencing gels were used to separate PCR products and showed good resolving ability in comparison with agarose gels. RAPD primers could be successfully used with ISSR primers for the detection of new genomic loci and applied in a new way for genomic mapping, fingerprinting, and gene tagging.     

Bactericidal Activity of Glycinecin A, a Bacteriocin Derived from Xanthomonas campestris pv. glycines, on Phytopathogenic Xanthomonas campestris pv. vesicatoria Cells

The ability of glycinecin A, a bacteriocin derived from Xanthomonas campestris pv. glycines 8ra, to kill closely related bacteria has been demonstrated previously by our group (S. G. Heu et al., Appl. Environ. Microbiol. 67:4105-4110, 2001). In the present study, we aimed at determining the glycinecin A-induced cause of death. Treatment with glycinecin A caused slow dissipation of membrane potential and rapid depletion of the pH gradient. Glycinecin A treatment also induced leakage of potassium ions from X. campestris pv. vesicatoria YK93-4 cells and killed sensitive bacterial cells in a dose-dependent manner. Sensitive cells were killed within 2 h of incubation, most likely due to the potassium ion efflux caused by glycinecin A. These results suggest that the bactericidal mechanism of action of glycinecin A is correlated with the permeability of membranes to hydroxyl and potassium ions, leading to the lethal activity of the bacteriocin on the target bacteria.     

Temperature regulates tuber-inducing lipoxygenase-derived metabolites in potato (Solanum tuberosum)

Temperature is one of the major environmental factors affecting potato tuberization. It has been suggested that lipoxygenase (LOX) mediates between temperature and tuber induction. In this study, the contents of the LOX-derived metabolites hydroperoxylinolenic acid (HPOT), jasmonic acid (JA), tuberonic acid (TA) and tuberonic acid glucoside (TAG) were analyzed in leaves of potatoes growing at different temperatures. At low, tuber-inducing temperature, endogenous levels of JA, TA and TAG rise, indicating their crucial role in tuber induction. The concentration of 13(S)-HPOT seems not to be directly affected by temperature. Instead, the molecule has only a short half-life in leaves and is readily metabolized.     

Necrostatin-1 protects against glutamate-induced glutathione depletion and caspase-independent cell death in HT-22 cells

Glutamate, a major excitatory neurotransmitter in the CNS, plays a critical role in neurological disorders such as stroke and Parkinson's disease. Recent studies have suggested that glutamate excess can result in a form of cell death called glutamate-induced oxytosis. In this study, we explore the protective effects of necrostatin-1 (Nec-1), an inhibitor of necroptosis, on glutamate-induced oxytosis. We show that Nec-1 inhibits glutamate-induced oxytosis in HT-22 cells through a mechanism that involves an increase in cellular glutathione (GSH) levels as well as a reduction in reactive oxygen species production. However, Nec-1 had no protective effect on free radical-induced cell death caused by hydrogen peroxide or menadione, which suggests that Nec-1 has no antioxidant effects. Interestingly, the protective effect of Nec-1 was still observed when cellular GSH was depleted by buthionine sulfoximine, a specific and irreversible inhibitor of glutamylcysteine synthetase. Our study further demonstrates that Nec-1 significantly blocks the nuclear translocation of apoptosis-inducing factor (a marker of caspase-independent programmed cell death ) and inhibits the integration of Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 (a pro-death member of the Bcl-2 family) into the mitochondrial membrane. Taken together, these results demonstrate for the first time that Nec-1 prevents glutamate-induced oxytosis in HT-22 cells through GSH related as well as apoptosis-inducing factor and Bcl-2/adenovirus E1B 19 kDa-interacting protein 3-related pathways.     

尼古丁调节大鼠冠状动脉平滑肌细胞大电导钙激活钾通道

目的:研究尼古丁对Wistar大鼠冠状动脉平滑肌大电导钙激活钾通道(BKca)活性的抑制作用及其细胞信号转导机制。方法:8周雄性Wistar大鼠随机分为两组:生理盐水组和尼古丁组;分别予以生理盐水和尼古丁2mg/(kg.d)注射21 d,蛋白酶法分离冠状动脉血管平滑肌细胞,将两组平滑肌细胞分别以对氯苯硫基环腺苷酸(CPT-cAMP,100μmol/L)和佛司可林(forskolin,10μmol/L)干预,单通道膜片钳记录干预前后平滑肌细胞单通道电流的平均开放时间(To)、平均关闭时间(Tc)、平均开放概率(Po)。结果:CPT-cAMP和Forskolin均能显著延长生理盐水组大鼠BKca的平均开放时间,缩短平均关闭时间,增加通道开放概率(P均<0.01)。对尼古丁组BKca的To、Tc、Po均无明显影响。结论:尼古丁促使冠状动脉血管收缩的生理机制是通过抑制cAMP/PKA途径诱导的大电导钙激活钾通道活性增加实现的。     

Lnc-PFAR facilitates autophagy and exacerbates pancreatic fibrosis by reducing pre-miR-141 maturation in chronic pancreatitis

Chronic pancreatitis (CP) is described as progressive inflammatory fibrosis of pancreas, accompanied with irreversible impaired endocrine and exocrine insufficiency. Pancreatic stellate cells (PSCs) are widely distributed in the stroma of the pancreas and PSCs activation has been shown as one of the leading causes for pancreatic fibrosis. Our previous study has revealed that autophagy is dramatically activated in CP tissues, which facilitates PSCs activation and pancreatic fibrosis. Long non-coding RNAs (LncRNAs) have been recognized as crucial regulators for fibrosis-related diseases. LncRNAs interact with RNA binding protein or construct competitive endogenous RNA (ceRNA) hypothesis which elicited the fibrotic processes. Until now, the effects of lncRNAs on PSCs activation and pancreatic fibrosis have not been clearly explored. In this study, a novel lncRNA named Lnc-PFAR was found highly expressed in mouse and human CP tissues. Our data revealed that Lnc-PFAR facilitates PSCs activation and pancreatic fibrosis via RB1CC1-induced autophagy. Lnc-PFAR reduces miR-141 expression by suppressing pre-miR-141 maturation, which eventually upregulates the RB1CC1 and fibrosis-related indicators expression. Meanwhile, Lnc-PFAR enhanced PSCs activation and pancreatic fibrosis through trigging autophagy. Our study interrogates a novel lncRNA-induced mechanism in promoting the development of pancreatic fibrosis, and Lnc-PFAR is suggested to be a prospective therapeutic target in clinical scenarios.Subject terms: RNAi, Diagnostic markers, Chronic pancreatitis     

FLZ Alleviates the Memory Deficits in Transgenic Mouse Model of Alzheimer’s Disease via Decreasing Beta-Amyloid Production and Tau Hyperphosphorylation

Alzheimer’s disease (AD) is the most common cause of dementia worldwide and mainly characterized by the aggregated β-amyloid (Aβ) and hyperphosphorylated tau. FLZ is a novel synthetic derivative of natural squamosamide and has been proved to improve memory deficits in dementia animal models. In this study, we aimed to investigate the mechanisms of FLZ’s neuroprotective effect in APP/PS1 double transgenic mice and SH-SY5Y (APPwt/swe) cells. The results showed that treatment with FLZ significantly improved the memory deficits of APP/PS1 transgenic mice and decreased apoptosis of SH-SY5Y (APPwt/swe) cells. FLZ markedly attenuated Aβ accumulation and tau phosphorylation both in vivo and in vitro. Mechanistic study showed that FLZ interfered APP processing, i.e., FLZ decreased β-amyloid precursor protein (APP) phosphorylation, APP-carboxy-terminal fragment (APP-CTF) production and β-amyloid precursor protein cleaving enzyme 1 (BACE1) expression. These results indicated that FLZ reduced Aβ production through inhibiting amyloidogenic pathway. The mechanistic study about FLZ’s inhibitory effect on tau phosphorylation revealed t the involvement of Akt/glycogen synthase kinase 3β (GSK3β) pathway. FLZ treatment increased Akt activity and inhibited GSK3β activity both in vivo and in vitro. The inhibitory effect of FLZ on GSK3β activity and tau phosphorylation was suppressed by inhibiting Akt activity, indicating that Akt/GSK3β pathway might be the possible mechanism involved in the inhibitory effect of FLZ on tau hyperphosphorylation. These results suggested FLZ might be a potential anti-AD drug as it not only reduced Aβ production via inhibition amyloidogenic APP processing pathway, but also attenuated tau hyperphosphoylation mediated by Akt/GSK3β.