氧化型胆固醇诱导血管细胞凋亡的机制

氧化型胆固醇（Ch—Ox）能诱导血管细胞凋亡,它是氧化低密度脂蛋白诱导细胞凋亡的主要活性成分之一,在动脉粥样硬化的形成过程中起重要作用。本文综合目前Ch—Ox的细胞毒性作用的研究进展,讨论了Ch-Ox诱导细胞凋亡的可能机制,并对凋亡的两种可能途径及信号转导进行分析,认为Ch-Ox通过线粒体途径诱导细胞凋亡已得到大量研究结果的证明;而通过死亡受体途径的可能性仍有待于进一步研究;胞内钙离子浓度的升高是Ch—Ox诱导细胞凋亡的早期信号转导事件;活性氧在Ch-Ox诱导细胞凋亡过程中也可能作为第二信使发挥重要作用。     

猪丁型冠状病毒诱导的细胞线粒体凋亡

猪丁型冠状病毒(Porcine deltacoronavirus,PDCoV)是一种新型的猪肠道致病性冠状病毒,可引起猪群剧烈腹泻及呕吐,但致病机制尚不清楚。本研究检测了PDCoV感染诱导的细胞凋亡。Caspase酶活性检测显示,在PDCoV感染的细胞中,caspase 3、caspase 8和caspase 9的活性随病毒感染量的增多而显著提高,类似的现象未能在紫外灭活病毒感染的细胞中观察到,表明PDCoV感染可同时激活内源性与外源性细胞凋亡通路,并暗示细胞凋亡的诱导依赖于病毒复制。为深入探究PDCoV诱导的内源性细胞凋亡,分别检测胞浆和线粒体中细胞色素C与凋亡诱导因子。结果显示,与正常细胞相比,PDCoV感染细胞从线粒体释放到胞浆的细胞色素C显著增多,且其释放量随着感染时间的延长而增多,而凋亡诱导因子始终定位于线粒体,提示PDCoV感染通过促使线粒体膜间隙的细胞色素C进入胞浆而启动caspase依赖的线粒体凋亡通路。本研究初步揭示了PDCoV诱导细胞凋亡的机制。     

离子胁迫诱导洋葱鳞茎内表皮细胞凋亡

通过不同浓度离子胁迫诱导剂(NaCl、CaCl2)对洋葱鳞茎内表皮细胞进行不同时间的处理,发现0.1M、0.5M的NaCl和CaCl2处理2小时即可诱导出细胞凋亡现象,随处理时间延长直至10小时,细胞核凋亡的形态学变化和凋亡小体更加明显,基因组DNA降解更加梯状条带化。本实验对离子诱导的洋葱鳞茎内表皮细胞凋亡现象做了较系统的描述,为植物细胞凋亡的研究及细胞凋亡实验教学提供了经济、快捷、有效的诱导方法。     

PrP106-126多肽诱导凋亡细胞中14-3-3β的降解

本研究将PrP106-126多肽和HeLa细胞共孵育4h和8h,采用Hoechst染色分析发现PrP106-126诱导凋亡细胞细胞核出现不同程度的染色质浓集,固缩及碎裂的细胞凋亡征象。Western blotting检测发现PrP106-126诱导细胞中的多聚ADP核糖聚合酶(poly ADP-ribose polymerase,PARP)降解,提示PrP106-126通过caspase3途径引起细胞凋亡现象。PrP106-126诱导的细胞中14-3-3β在不同孵育时间也出现降解,而Real-time PCR检测14-3-3β mRNA未发生变化。本研究证明PrP106-126通过caspase3诱导HeLa细胞凋亡,并可导致抗凋亡蛋白14-3-3β的降解而加速凋亡的形成。     

猪链球菌2型溶菌酶释放蛋白诱导上皮细胞融合和凋亡

猪链球菌2型（SS2）溶菌酶释放蛋白(MRP)的致病作用迄今不明,为此,以Hep2细胞为上皮细胞体外模型,将纯化的MRP溶液和细胞共孵育,光镜观察,发现MRP可诱导细胞发生两种典型形态学变化：一是诱导细胞融合形成多核巨细胞,随后巨细胞发生凋亡;二是诱导单个细胞凋亡。透射电镜观察和流式细胞分析确证MRP具有诱导上皮细胞凋亡的功能,凋亡率达18%。证明MRP可单独作为SS2的毒力因子。     

土荆芥挥发油对蚕豆根尖细胞的化感潜力

化感作用是外来植物成功入侵的机制之一。本研究以蚕豆根尖为材料,采用DNA Ladder分析技术和蚕豆根尖微核技术,分析了入侵植物土荆芥挥发油经土壤载体诱导的细胞凋亡以及对细胞的遗传损伤。结果表明：（1）经挥发油处理24 h和48 h,低剂量（＜5 μL）挥发油对蚕豆根的生长与根尖细胞有丝分裂具有显著的促进作用,但随着处理剂量增大（＞5 μL）和处理时间延长,根的生长与细胞有丝分裂过程明显受到抑制。（2）挥发油具有诱导染色体畸变的效应,根尖细胞微核率随处理剂量增加和时间延长而增大,但当挥发油剂量大于15 μL,这种诱导效应降低。（3）通过DNA Ladder分析,经挥发油处理后根尖细胞发生了凋亡,其中24 h处理组DNA未发生特异性降解,当剂量大于15 μL处理48 h和剂量大于10 μL处理72 h后,DNA开始发生特异性降解,形成DNA Ladder,表明随着挥发油剂量增大和作用时间延长,细胞凋亡过程加剧。本研究结果表明土荆芥释放的挥发性化感物质能以土壤为载体对根细胞产生影响。     

植物生长发育中程序性细胞死亡

本文简要介绍了植物细胞凋亡的一些特点以及植物在营养生长和生殖生长过程中发生的细胞凋亡现象。指出细胞凋亡是植物生长发育过程中正常的生理现象。     

参与细胞凋亡的核酸酶

细胞凋亡是机体内一种重要而且保守的细胞去除机制。染色质的降解是凋亡的重要标志之一,它需要核酸酶的参与。到目前为止,参与凋亡的核酸内切酶可以分为三类:DNaseⅠ家族,DNaseⅡ家族,CAD。不同的细胞在凋亡的时候会激活不同的核酸酶,相同的细胞在不同的诱导方式下也会激活不同的核酸酶,因此,凋亡过程中,那些核酸酶的激活是由细胞种类和诱导方式等特异性所决定的。     

来源于鸡贫血病毒的凋亡素研究进展

肿瘤化疗药物多以p53依赖性途径诱导细胞凋亡,而许多肿瘤在发生过程中丧失了D53功能;此外,在肿瘤发生过程中往往伴随着抑制细胞凋亡的bcl-2蛋白的高水平表达。而来源于鸡贫血病毒的凋亡素能够选择性地诱导肿瘤细胞和转化细胞发生凋亡,并以非p53依赖性途径诱导细胞凋亡,不受bcl-2蛋白的抑制作用。因此,凋亡素作为1种抗肿瘤制剂用于肿瘤治疗能够选择性地诱导肿瘤细胞和转化细胞发生凋亡,而并不杀伤人和鼠的正常二倍体细胞,且无毒副作用…,具有很好的临床应用前景。     

狂犬病毒感染与细胞凋亡

在狂犬病毒感染中,宿主细胞会发生凋亡性坏死.研究表明,在病毒感染过程中,狂犬病毒糖蛋白及基质蛋白均能诱导宿主细胞发生凋亡,有许多凋亡分子参与这个过程并起着作用.理解狂犬病毒感染与细胞凋亡的关系以及凋亡发生的可能机制,能为狂犬病的防治提供一些药物研究上的新思路.     

15N-ammonium and 15N-nitrate uptake of a 15-year-old Picea abies plantation

Throughfall nitrogen of a 15-year-old Picea abies (L.) Karst. (Norway spruce) stand in the Fichtelgebirge, Germany, was labeled with either ¹⁵N-ammonium or ¹⁵N-nitrate and uptake of these two tracers was followed during two successive growing seasons (1991 and 1992). ¹⁵N-labeling (62 mg ¹⁵N m^-2 under conditions of 1.5 g N m^-2 atmospheric nitrogen deposition) did not increase N concentrations in plant tissues. The ¹⁵N recovery within the entire stand (including soils) was 94%±6% of the applied ¹⁵N-ammonium tracer and 100%±6% of the applied ¹⁵N-nitrate tracer during the 1st year of investigation. This decreased to 80%±24% and 83%±20%, respectively, during the 2nd year. After 11 days, the ¹⁵N tracer was detectable in 1-year-old spruce needles and leaves of understory species. After 1 month, tracer was detectable in needle litter fall. At the end of the first growing season, more than 50% of the ¹⁵N taken up by spruce was assimilated in needles, and more than 20% in twigs. The relative distribution of recovered tracer of both ¹⁵N-ammonium and ¹⁵N-nitrate was similar within the different foliage age classes (recent to 11-year-old) and other compartments of the trees. ¹⁵N enrichment generally decreased with increasing tissue age. Roots accounted for up to 20% of the recovered ¹⁵N in spruce; no enrichment could be detected in stem wood. Although ¹⁵N-ammonium and ¹⁵N-nitrate were applied in the same molar quantities (¹⁵NH ₄ ⁺ : ¹⁵NO ₃ ^- =1:1), the tracers were diluted differently in the inorganic soil N pools (¹⁵NH ₄ ⁺ /NH ₄ ⁺ : ¹⁵NO ₃ ^- /NO ₃ ^- =1:9). Therefore the measured ¹⁵N amounts retained by the vegetation do not represent the actual fluxes of ammonium and nitrate in the soil solution. Use of the molar ammonium-to-nitrate ratio of 9:1 in the soil water extract to estimate ¹⁵N uptake from inorganic N pools resulted in a 2–4 times higher ammonium than nitrate uptake by P. abies.     

Combined IL-15/IL-15Ralpha immunotherapy maximizes IL-15 activity in vivo

IL-15 has substantial potential as an immunotherapeutic agent for augmenting immune responses. However, the activity of IL-15 is mediated by a unique mechanism in which the cytokine is transpresented by cell-bound high-affinity IL-15Ralpha to target cells expressing the IL-15Rbeta and the common gamma-chain. Thus, the efficacy of administered IL-15 alone may be limited by the availability of free IL-15Ralpha. We now show that administration of soluble IL-15/IL-15Ralpha complexes greatly enhanced IL-15 half-life and bioavailability in vivo. Treatment of mice with this complex, but not with IL-15 alone, resulted in robust proliferation of memory CD8 T cells, NK cells, and NK T cells. The activity of the complex required IL-15Rbeta, but not IL-15Ralpha, expression by the responding cells and was IL-7-independent. Interestingly, IL-15/IL-15Ralpha immunotherapy also caused naive CD8 T cell activation and development into effector cells and long-term memory T cells. Lastly, complexed IL-15, as compared with IL-15 alone, dramatically reduced tumor burden in a model of B16 melanoma. These findings hold significant importance for the use of IL-15 as a potential adjuvant/therapeutic and inducer of homeostatic proliferation, without the necessity for prior immunodepletion.     

Semisynthesis of Arg15, Glu15, Met15, and Nle15-aprotinin involving enzymatic peptide bond resynthesis

The semisynthesis of homologues of aprotinin, the bovine pancreatic trypsin inhibitor, is described. The P₁ lysine¹⁵ residue was replaced by two methods. The first procedure, which consisted of two enzymatic steps for the incorporation of other amino acids has previously been described. The second approach consisted of six steps of both enzymatic and chemical nature. The modified inhibitor, in which the lysine¹⁵-alanine¹⁶ peptide bond is hydrolyzed, was used as the starting material. All carboxyl groups of the modified inhibitor were esterified with methanol; the lysine¹⁵ methylester group was then selectively hydrolyzed. Afterward, lysine¹⁵ itself was split off. Arginine, glutamic acid, methionine, andl-2-aminohexanoic acid (norleucine, Nle) were incorporated using water-soluble carbodiimide combined with an acylation catalyst. The methylester group was used to prevent polymerization. The reactive-site peptide bonds were resynthesized using either chymotrypsin or trypsin.     

The Prader-Willi syndrome and 15-15 translocation]

The association of the Willi-Prader syndrome and a t(15q15q) is reported. This, in conjunction with an earlier report of this association, suggests that a gene related to the Willi-Prader syndrome may be present on chromosome 15.     

Epidermal growth factor pathway substrate 15, Eps15.

Eps15 was originally identified as a substrate for the kinase activity of the epidermal growth factor receptor (EGFR). Eps15 has a tripartite structure comprising a NH2-terminal portion, which contains three EH domains, a central putative coiled-coil region, and a COOH-terminal domain containing multiple copies of the amino acid triplet Aspartate-Proline-Phenylalanine. A pool of Eps15 is localized at clathrin coated pits where it interacts with the clathrin assembly complex AP-2 and a novel AP-2 binding protein, Epsin. Perturbation of Eps15 and Epsin function inhibits receptor-mediated endocytosis of EGF and transferrin, demonstrating that both proteins are components of the endocytic machinery. Since the family of EH-containing proteins is implicated in various aspects of intracellular sorting, biomolecular strategies aimed at interfering with these processes can now be envisioned. These strategies have potentially far reaching implications extending to the control of cell proliferation. In this regard, it is of note that Eps15 has the potential of transforming NIH-3T3 cells and that the eps15 gene is rearranged with the HRX/ALL/MLL gene in acute myelogeneous leukemias, thus implicating this protein in the subversion of cell proliferation in neoplasia.     

Formation of 15alpha-hydroxyestriol and 15alpha-hydroxyestradiol from C19 15alpha-hydroxylated precursors in human pregnancy.

A mixture of 3H-15alpha-hydroxyandrostenedione and 14C-15alpha-hydroxydehydroisoandrosterone was injected intravenously into two subjects in the third trimester of pregnancy and, in a second study, directly into two fetuses in utero during transfusion for erythroblastosis fetalis. The urine was collected for 4-5 days and steroid conjugates in the urine were hydrolyzed into sulfate and glucosiduronate fractions. From the glucosiduronate fraction 15alpha-hydroxyestriol, 15alpha-hydroxyestradiol, 15alpha-hydroxyandrostenedione and 15alpha-hydroxydehydroisoandrosterone were isolated. No metabolites were identified in the sulfate fraction of the urine. A marked difference was observed in the metabolism of 15alpha-hydroxyandrostenedione and 15alpha-hydroxydehydroisoandrosterone which is dependent on the route of administration of the substrates. Both substrates were converted to 15alpha-hydroxyestriol and 15alpha-hydroxyestradiol, and the 3H/14C ratios and percentage conversions suggest that 15alpha-hydroxyandrostenedione seems to be a better precursor of the urinary 15alpha-hydroxylated estrogens than 15alpha-hydroxydehydroisoandrosterone. The 3H/14C ratios also suggest that 15alpha-hydroxydehydroisoandrosterone was converted to 15alpha-hydroxyestriol via 15alpha-hydroxyandrostenedione, and that the formation of 15alpha-hydroxyestradiol from 15alpha-hydroxydehydroisoandrosterone via 15alpha-hydroxyandrostenedione is a pathway of minor importance. Finally, 15alpha-hydroxydehydroisoandrosterone was recovered from the urine only when the precursors were injected into the maternal circulation. Also, an unknown metabolite containing only 14C was detected in the glucosiduronate fraction of the urine of each subject.