Identification of p53 Sequence Elements That Are Required for MDM2-Mediated Nuclear Export

It has been demonstrated that MDM2 can differentially regulate subcellular distribution of p53 and its close structural homologue p73. In contrast to MDM2-mediated p53 nuclear export, p73 accumulates in the nucleus as aggregates that colocalize with MDM2. Distinct distribution patterns of p53 and p73 suggest the existence of unique structural elements in the two homologues that determine their MDM2-mediated relocalization in the cell. Using a series of p53/p73 chimeric proteins, we demonstrate that three regions of p53 are involved in the regulation of MDM2-mediated nuclear export. The DNA binding domain (DBD) is involved in the maintenance of a proper conformation that is required for functional activity of the nuclear export sequence (NES) of p53. The extreme C terminus of p53 harbors several lysine residues whose ubiquitination by MDM2 appears to be the initial event in p53 nuclear export, as evidenced by the impaired nucleocytoplasmic shuttling of p53 mutants bearing simultaneous substitutions of lysines 370, 372, 373, 381, 382, and 386 to arginines (6KR) or alanines (6KA). Finally, the region between the DBD and the oligomerization domain of p53, specifically lysine 305, also plays a critical role in fully revealing p53NES. We conclude that MDM2-mediated nuclear export of p53 depends on a series of ubiquitination-induced conformational changes in the p53 molecule that lead to the activation of p53NES. In addition, we demonstrate that the p53NES may be activated without necessarily disrupting the p53 tetramer.     

Preliminary study on a potential panel for quality assurance of ELISPOT

The ELISPOT assay is increasingly used for assessing cellular immune responses in clinical trials of HIV-1 or cancer vaccines. However, to date, data from clinical trials do not consistently show that immune responses are correlated with clinical endpoints. This is due in part to the lack of assay standardization and validation across laboratories and therefore, a quality control panel is required to establish competency and comparability amongst different laboratories. In this study peripheral blood mononuclear cells (PBMCs) from healthy individuals were screened and frozen in liquid nitrogen. The recovery and viability of the PBMCs and the frequencies of interferon (IFN)-γ-secreting cells after CEF peptide pool stimulation were detected after various intervals in seven different laboratories. The recovery and viability did not differ significantly after different intervals. Although the frequencies of IFN (interferon)-γ-secreting cells among thawed PBMCs (peripheral blood mononuclear cells) fluctuated after CEF peptide pool stimulation at different intervals, they were not significantly decreased compared with those among fresh PBMCs. However, the viabilities, recoveries and frequencies of IFN-γ-secreting cells differed significantly among the seven laboratories. Our results indicate that cryopreserved PBMCs could be used as a quality control panel for ELISPOT. However, the procedures for ELISPOT need to be standardized amongst different laboratories.     

陆地棉花药愈伤组织的诱导和继代培养

花药培养是自６０年代以来发展起来的一项生物技术,旨在诱导出单倍体花粉植株,应用于育种实践和基础研究〔１〕。以单倍体植株为基础的单倍体育种被认为在以下几个方面具有优越性：第一,缩短育种年限;第二,排除杂种优势对后代选择的干扰〔２,３〕。此外,花药培养在...     

滇黄芩中的两个酮甙

从龙胆科滇黄芩属植物滇黄芩(Veratrilla baillonii Franch.)中分离得到两个新的(口山)酮甙,分别命名为:滇黄芩甙C(I)和滇黄芩甙D(Ⅱ).经各种光谱解析及化学反应证明,其结构推定为:2,3,4,5-四甲氧(口山)酮-1-O-β-D-吡喃葡萄糖基(6←l)-β-D-吡喃木糖甙(I)和3,4,5-三甲氧基(口山)酮-1-O-β-D-吡喃葡萄糖基(6←1)-β-D-吡喃本糖甙(Ⅱ).     

中国钩端螺旋体rRNA基因多态性分析

以ＤｉｇｄＵＴＰ标记的１６ＳｒＲＮＡ及２３ＳｒＲＮＡ基因为探针,分析了八个血清群５４个血清型６４株国内外致病性钩端螺旋体参考株和２７株野生株染色体经限制性内切酶ＥｃｏＲⅠ消化后的ｒＲＮＡ基因限制性图谱。结果发现,９１株菌中共有５６个核糖核酸型（Ｒｉｂｏｔｙｐｅ,简称ＲＴ）,除部分血清群中少数不同的血清型有相同的ＲＴ型外,大部分血清型都有独特的ＲＴ型,同一血清群往往拥有共同的核心片段;除黄疸出血群的黄疸出血型外,同一血清型的国内和国际参考株的ＲＴ型不相同;大多数野生株的ＲＴ和相应血清型国内参考株相同,差异也只表现为谱形上个别带型的缺少和增加,所研究的波摩那型野生株的ＲＴ型和国际参考株相同而和国内参考株不同     

Emerging Piezo1 signaling in inflammation and atherosclerosis; a potential therapeutic target

Purpose of Review: Atherosclerosis is the principal cause of cardiovascular diseases (CVDs) which are the major cause of death worldwide. Mechanical force plays an essential role in cardiovascular health and disease. To bring the awareness of mechanosensitive Piezo1 role in atherosclerosis and its therapeutic potentials we review recent literature to highlight its involvement in various mechanisms of the disease.Recent Findings: Recent studies reported Piezo1 channel as a sensor, and transducer of various mechanical forces into biochemical signals, which affect various cellular activities such as proliferation, migration, apoptosis and vascular remodeling including immune/inflammatory mechanisms fundamental phenomenon in atherogenesis.Summary: Numerous evidences suggest Piezo1 as a player in different mechanisms of cell biology, including immune/inflammatory and other cellular mechanisms correlated with atherosclerosis. This review discusses mechanistic insight about this matter and highlights the drugability and therapeutic potentials consistent with emerging functions Piezo1 in various mechanisms of atherosclerosis. Based on the recent works, we suggest Piezo1 as potential therapeutic target and a valid candidate for future research. Therefore, a deeper exploration of Piezo1 biology and translation towards the clinic will be a novel strategy for treating atherosclerosis and other CVDs.     

Complement factor H deficiency combined with smoking promotes retinal degeneration in a novel mouse model

Age-related macular degeneration is the leading cause of blindness in the elderly. The Y402H polymorphism in complement factor H promotes disease-like pathogenesis, and a Cfh^+/− murine model can replicate this phenotype, but only after two years. We reasoned that by combining CFH deficiency with cigarette smoke exposure, we might be able to accelerate disease progression to facilitate preclinical research in this disease. Wild-type and Cfh^+/− mice were exposed to nose-only cigarette smoke for three months. Retinal tissue morphology and visual function were evaluated by optical coherence tomography, fundus photography and autofluorescence, and electroretinogram. Retinal pigment epithelial cell phenotype and ultrastructure were evaluated by immunofluorescence staining and transmission electron microscopy. Cfh^+/− smoking mice showed a dome-like protruding lesion at the ellipsoid zone (drusen-like deposition), many retinal hyper-autofluorescence spots, and a marked decrease in A- and B-wave amplitudes. Compared with non-smoking mice, wild-type and Cfh^+/− smoking mice showed sub-retinal pigment epithelium complement protein 3 deposition, activation of microglia, metabolic waste accumulation, and impairment of tight junctions. Microglia cells migrated into the photoreceptor outer segment layer in Cfh^+/− smoking mice showed increased activation. Our results suggest that exposing Cfh^+/− mice to smoking leads to earlier onset of age-related macular degeneration than in other animal models, which may facilitate preclinical research into the pathophysiology and treatment of this disease.     

Mitochondrial replacement in macaque monkey offspring by first polar body transfer

Dear Editor, Mitochondrial DNA(mtDNA)mutations are maternally inherited to the offspring and mitochondrial replacement therapy(MRT)provides a promising approach...     

长江上游朱杨溪江段圆筒吻鮈种群参数和资源量

圆筒吻鮈为长江上游特有种,三峡、向家坝、溪洛渡等梯级水利工程的建设,可能对其物种生存产生较大影响。为了解三峡工程蓄水后、金沙江一期工程蓄水前该物种的种群动态,2007-2009年对长江上游朱杨溪江段的圆筒吻鮈进行了调查,利用体长频率数据对其种群参数和资源量进行了估算。长江上游朱杨溪江段圆筒吻鮈渔获群体体长范围为69.0-268.0mm,体重范围为3.9-230.4 g,平均体长为(181.4±26.9)mm,平均体重为(78.5±33.0)g;优势体长组为125.0-225.0 mm,约占总数的93.0%。圆筒吻鮈体长体重关系为:W=1.58×10~(-5)L~(2.95)(R~2=0.94,P0.01,n=401),为匀速生长类型,可用Von Bertalalfffy生长方程描述其生长规律。圆筒吻鮈生长参数为,L_∞=361 mm、k=0.21a~(-1)、t_0=-0.68;死亡系数为Z=1.70、M=0.50、F=1.20。其开捕体长为163.4 mm资源开发率为0.70超过了其资源最适开发率(0.60)而接近最大开发率(0.75)。2007-2009年朱杨溪江段圆筒吻鮈年渔获量分别为6716尾(0.50t)、22772尾(1.87 t)和16139尾(1.20 t),平均值为15209尾(1.19 t)。由体长股分析法估算出2007-2009年朱杨溪江段圆筒吻鮈年资源量分别为16361尾/km(1.25 t/km)、13922尾/km(1.74 t/km)和26836尾/km.(1.93 t/km)均值为19040尾/km(1.64 t/km)。目前圆筒吻鮈资源开发率偏高,建议提高开捕体长至193.5 mm,降低其开发率。建议逐步引导渔民转产转业,实施全年禁渔措施,加强筒吻鮈等特有鱼类的保护。     

大孔树脂纯化嘉宝果叶片多酚及其生物活性和组成分析

为探讨嘉宝果(Myrciaria cauliflora)叶片多酚的分离纯化方法,对4种树脂(NKA-2、NKA-9、HPD-826和HPD-400A)进行了筛选,并分析了其多酚的抗氧化、体外降糖活性和组成成分。结果表明,NKA-9树脂适于嘉宝果叶片多酚纯化,最佳工艺条件为:上样液质量浓度2.00 mg/mL、洗脱液乙醇体积分数70%、上样流速1.0 mL/min、上样量204 mL、洗脱流速0.9 mL/min、洗脱量70 mL。嘉宝果叶多酚纯度可达69.86%。嘉宝果叶片纯化后的多酚抗氧化及α-葡萄糖苷酶抑制活性高于纯化前,但α-淀粉酶抑制活性低于纯化前。HPLC结果表明,嘉宝果叶片中含有杨梅苷、芦丁、金丝桃苷和鞣花酸,其中鞣花酸含量最高[(16.15±0.49) mg/g]。因此,NKA-9树脂适合分离纯化嘉宝果叶片多酚,纯化后的多酚抗氧化及α-葡萄糖苷酶抑制活性增强。