Antagonist effect of triptolide on AKT activation by truncated retinoid X receptor-alpha

Background

Retinoid X receptor-alpha (RXRα) is a key member of the nuclear receptor superfamily. We recently demonstrated that proteolytic cleavage of RXRα resulted in production of a truncated product, tRXRα, which promotes cancer cell survival by activating phosphatidylinositol-3-OH kinase (PI3K)/AKT pathway. However, how the tRXRα-mediated signaling pathway in cancer cells is regulated remains elusive.

Methodology/Principal Findings

We screened a natural product library for tRXRα targeting leads and identified that triptolide, an active component isolated from traditional Chinese herb Trypterygium wilfordii Hook F, could modulate tRXRα-mediated cancer cell survival pathway in vitro and in animals. Our results reveal that triptolide strongly induces cancer cell apoptosis dependent on intracellular tRXRα expression levels, demonstrating that tRXRα serves as an important intracellular target of triptolide. We show that triptolide selectively induces tRXRα degradation and inhibits tRXRα-dependent AKT activity without affecting the full-length RXRα. Interestingly, such effects of triptolide are due to its activation of p38. Although triptolide also activates Erk1/2 and MAPK pathways, the effects of triptolide on tRXRα degradation and AKT activity are only reversed by p38 siRNA and p38 inhibitor. In addition, the p38 inhibitor potently inhibits tRXRα interaction with p85α leading to AKT inactivation. Our results demonstrate an interesting novel signaling interplay between p38 and AKT through tRXRα mediation. We finally show that targeting tRXRα by triptolide strongly activates TNFα death signaling and enhances the anticancer activity of other chemotherapies

Conclusions/Significance

Our results identify triptolide as a new xenobiotic regulator of the tRXRα-dependent survival pathway and provide new insight into the mechanism by which triptolide acts to induce apoptosis of cancer cells. Triptolide represents one of the most promising therapeutic leads of natural products of traditional Chinese medicine with unfortunate side-effects. Our findings will offer new strategies to develop improved triptolide analogs for cancer therapy.     

Recombinase polymerase amplification combined with lateral flow dipstick for the rapid detection of Chattonella marina

Journal of Applied Phycology - Chattonella marina (Raphidophyceae) is a common microalgal species that has frequently caused harmful algal blooms (HABs). Here, recombinase polymerase amplification...     

绿脓杆菌对鲎素耐受性特点及耐受性机制的研究

【目的】为了探讨鲎素作为抗菌药物在临床使用中的安全性问题,通过鲎素连续增高浓度法对绿脓杆菌进行耐受性诱导,并对其耐受性机制进行初步研究,以期为鲎素的广泛应用提供理论依据。【方法】绿脓杆菌ATCC27853为试验菌株,通过连续增高浓度诱导法筛选抗药菌株,并通过抗药稳定性、交叉抗药性、抗药性代偿测定来探究其耐受性特点,通过对其胞外蛋白酶活性、生物膜形成、胞外多糖含量的变化来探讨其抗药性机制。【结果】通过连续增高鲎素浓度法对原始菌株进行30多代诱导后,绿脓杆菌ATCC27853对鲎素的MIC值逐渐增高,80多代时产生了明显抗药性。抗药菌株对丁胺卡那以及pexiganan、鲎素同源肽tachyplesin III、polyphemusin I均能产生不同程度的抗药性。在无药培养基中抗药菌株以更长的延滞期作为抗药性代偿,但在有药培养基中具有更短的延滞期和更大的生长速率。抗药菌株较原始菌株分泌的胞外蛋白酶活性增高,并能降低鲎素的抗菌活性。在同样条件下抗药菌株较原始菌株胞外多糖含量增高,更易形成生物膜。【结论】在长期选择压力下绿脓杆菌ATCC27853对鲎素能产生抗药性,其抗药性机制可能与生物膜形成、胞外蛋白酶失活鲎素有关。关于细菌对鲎素的抗药性机制,有待进一步研究。     

COVID-19确诊病例居住环境病毒检测结果分析及防控探讨

新型冠状病毒肺炎(COVID-19)传播速度快、感染范围广,其感染方式主要是聚集性感染,感染途径主要是呼吸道飞沫和接触传播。了解环境中,特别是COVID-19确诊病人生活环境中的病毒存在情况,是做好环境消毒,阻断新型冠状病毒(SARS-CoV-2)传播的重要步骤,对COVID-19防控具有重要意义。本研究旨在探讨COVID-19患者生活环境中SARS-CoV-2的存在情况,从SARS-CoV-2存在的空间部位、病毒核酸含量、消毒效果等方面对SARS-CoV-2的相关特点做出初步研究,为制定有效的SARS-CoV-2防控措施提供科学依据。本研究以COVID-19病例治疗前的3个家庭居住环境和治疗出院后隔离期间的2个宾馆居住环境中采集的样本为研究材料,采用RT-PCR方法检测样本中的SARS-CoV-2核酸并进行比较分析。结果显示,首次从3个家庭环境中采样48份,RTPCR检测SARS-CoV-2核酸阳性5份(10.42%),3个家庭的环境样本中均有阳性样本检出。首次采样48h后在家庭3进行第二次采样16份,SARS-CoV-2核酸检测阳性2份(12.5%),检测Ct值比首次升高。家庭3消毒后24h采集的16份样本SARS-CoV-2核酸检测均为阴性,并且两处宾馆环境采集的24份样本SARS-CoV-2核酸检测也均为阴性。本研究提示,COVID-19病例的生活环境中可以检出SARS-CoV-2,病毒存在区域、存在物品、病毒核酸含量均有差异;对外环境进行消毒可以达到消毒目的,能够起到阻断SARS-CoV-2传播的防控效果。     

仿刺参耳状幼体“烂边症”的病原及其来源分析

【目的】查明仿刺参耳状幼体"烂边症"的病原及其来源,并获得该病的治疗药物。【方法】对烂边症状较为典型的育苗场的发病幼体进行病原学分析,对可疑病原进行人工回接感染并进行形态学、生理生化和16S rDNA序列分析鉴定,对养殖场育苗系统,包括水源、饵料、育苗池水、育苗池底污物和亲参池水进行细菌学分析,对病原菌进行药敏测试。【结果】从患病幼体分离得到1种优势菌株,人工回接感染证明它对健康仿刺参有较强的致病性,且感染发病与自然发病仿刺参幼体的症状相同。鉴定出"烂边症"的病原为弧菌Vibrio lentus。养殖系统中的细菌浓度均较高(2.8×102-8.8×107cells/mL);病原来源较复杂:育苗池水、池底污物和亲参池水均发现了病原菌,病原菌浓度以池底污物中最多,育苗池水次之,亲参池水最少。新霉素等15种常用抗生素可有效抑制该病原菌的生长。【结论】"烂边症"的病原为弧菌Vibrio lentus;池底污物、育苗池及亲参均可能是本次"烂边症"的病原来源;新霉素等15种常用抗生素可用于该病的防治。     

大蒜A病毒CP基因的原核表达及抗血清制备

根据GenBank报道的大蒜A病毒(GarV-A)序列设计引物、扩增其外壳蛋白基因并进行序列分析.结果表明,GarV-A的CP基因与目前已报道的两种GarV-A不同分离物CP基因的核苷酸序列同源性为98％-99％;氨基酸序列同源性均为98％.将GarV-A CP基因插入表达载体pSBET,在大肠杆菌BL21(DE3)Plys E菌株中诱导表达.CP经12％SDS-PAGE和5％-20％SDS-PAGE两次纯化,免疫小鼠获得抗CP血清,Western blotting分析表明确定制备的抗体对CP具有高度特异性,ELISA检测表明制备的抗体能够与天然病毒离子结合,因此可以作为该病毒的检测.     

Neuroprotection of a Novel Cyclopeptide C*HSDGIC* from the Cyclization of PACAP (1–5) in Cellular and Rodent Models of Retinal Ganglion Cell Apoptosis

Purpose

To investigate the protective effects of a novel cyclopeptide C*HSDGIC* (CHC) from the cyclization of Pituitary adenylate cyclase-activating polypeptide (PACAP) (1–5) in cellular and rodent models of retinal ganglion cell apoptosis.

Methodology/Principal Findings

Double-labeling immunohistochemistry was used to detect the expression of Thy-1 and PACAP receptor type 1 in a retinal ganglion cell line RGC-5. The apoptosis of RGC-5 cells was induced by 0.02 J/cm² Ultraviolet B irradiation. MTT assay, flow cytometry, fluorescence microscopy were used to investigate the viability, the level of reactive oxygen species (ROS) and apoptosis of RGC-5 cells respectively. CHC attenuated apoptotic cell death induced by Ultraviolet B irradiation and inhibited the excessive generation of ROS. Moreover, CHC treatment resulted in decreased expression of Bax and concomitant increase of Bcl-2, as was revealed by western-blot analysis. The in vivo apoptosis of retinal ganglion cells was induced by injecting 50 mM N-methyl-D-aspartate (NMDA) (100 nmol in a 2 µL saline solution) intravitreally, and different dosages of CHC were administered. At day 7, rats in CHC+ NMDA-treated groups showed obvious aversion to light when compared to NMDA rats. Electroretinogram recordings revealed a marked decrease in the amplitudes of a-wave, b-wave, and photopic negative response due to NMDA damage. In retina receiving intravitreal NMDA and CHC co-treatment, these values were significantly increased. CHC treatment also resulted in less NMDA-induced cell loss and a decrease in the proportion of dUTP end-labeling-positive cells in ganglion cell line.

Conclusions

C*HSDGIC*, a novel cyclopeptide from PACAP (1–5) attenuates apoptosis in RGC-5 cells and inhibits NMDA-induced retinal neuronal death. The beneficial effects may occur via the mitochondria pathway. PACAP derivatives like CHC may serve as a promising candidate for neuroprotection in glaucoma.     

贵州省野生皂荚种实表型性状多样性分析

为深入了解贵州省野生皂荚(Gleditsia sinensis)荚果表型性状的遗传多样性及其变异类型,为皂荚的遗传改良、种质鉴定、亲本选择以及品种培育奠定理论基础。该研究以贵州省7个野生皂荚群体70个个体为研究对象,采用方差分析、主成分分析、相关性分析及多性状综合评价等方法对皂荚群体的10个种实表型性状进行系统分析和综合评价。结果显示：(1)所测皂荚的表型性状差异在群体内均达到极显著水平(P＜0.01);在群体间,除每荚粒数、种子宽、种子长宽积以及种子长宽比之外,其余表型性状的差异均达极显著水平(P＜0.01)。(2)7个居群野生皂荚各性状平均变异系数为21.16%,其中凯里市(P4)居群的变异系数最高(24.44%);居群间荚果的变异(29.22%)高于种子的变异(11.04%),且变异主要来自于群体内。(3)相关分析显示,皂荚种实各性状之间存在不同程度的关联性;主成分分析显示,前4个主成分(皂荚种子大小、单个荚果出籽数量、种子形态指数因子、与荚果长和种子厚相关的因子)的累积贡献率达69.783%,可基本反映皂荚表型性状的大部分信息;以10个种实性状对皂荚野生群体进行综合评价发现,来自于惠水县(P7)群体的皂荚种实性状综合评价最高。研究表明,贵州省野生皂荚在群体间及群体内具有丰富的表型变异,且群体内的变异大于群体间的变异,变异主要来自于群体内。     

油菜含油量相关基因Gpat、Lpat在不同肥密条件下表达规律研究

油菜是我国第一大自产油料作物,具有重要的食用、饲用等价值。提高油菜籽含油量一直是育种家们不懈追求的目标之一,不同的栽培措施对油菜含油量有较大影响,为了研究不同施肥量、种植密度对油菜中控制含油量相关基因Gpat、Lpat表达量的影响,本研究采用qRT-PCR测定不同时期、不同肥密条件下Gpat、Lpat基因的表达量,并对其表达情况进行了分析。研究得知:Gpat、Lpat表达量变化规律是相同的,即:随着氮肥的增加而降低,随着密度的增加而升高,随着硼肥的增加而先升高后下降。此外,本研究在A1B3C1、A1B2C2及A2B3C2处理下可同时促进Gpat与Lpat的表达,是比较理想的肥密条件,可为提高油菜的含油量提供参考。     

The naturally occurring xanthone α-mangostin induces ROS-mediated cytotoxicity in non-small scale lung cancer cells

Small cell lung cancer (NSCLC) accounts for 85% of total deaths globally, and recent studies indicate the increasing risks of NSCLC in China and South Asian countries. Hence, development of new therapeutics against NSCLC has been a major concern. α-Mangostin, a naturally occurring xanthone, found abundantly in pericarps of mangosteen fruit is well known for its medicinal importance. The anticancer properties of α-mangostin against several types of cancer are also well documented. But the mechanism of action of α-mangostin against lung cancer is not well understood and requires further investigation. Therefore in the present study, we explored the therapeutic potential of α-mangostin against A549 cells. Treatment of A549 cells with α-mangostin resulted in a dose-dependent loss of cell viability, while the non-malignant cells such as hPBMC and WI-38 remained unaffected. Further we observed that the ROS plays an important role in α-mangostin -induced apoptosis in A549 cells, and administration of N-acetyl cysteine significantly abrogates α-mangostin -mediated cytotoxicity in lung cancer cells. Overall, α-mangostin induces ROS-mediated cytotoxicity in NSCLC cells.