Bcl—2的抗细胞凋亡机制

Ｂｃｌ－２的抗细胞凋亡机制＠郑英如＠陈竹钦￥第三军医大学附属大坪医院Ｂｃｌ２的抗细胞凋亡机制郑英如陈竹钦（第三军医大学附属大坪医院，重庆６３００４２）ｂｃｌ２为一原癌基因，通过其所编码蛋白Ｂｃｌ２而发挥其抑制细胞凋亡的功能。在生理情况下，Ｂｃｌ２在...     

细胞色素c与细胞凋亡

在哺乳动物细胞凋亡的发生过程中,位于线粒体内膜外侧的细胞色素ｃ被释放进入胞质,作为辅助因子参与死亡蛋白酶－３的激活,后者在凋亡过程中起到重要作用。Ｂｃｌ－２、Ｂｃｌ－ＸＬ,Ｂａｘ可阻止或诱导线粒体细胞色素ｃ释放入胞质,这可能是Ｂｃｌ－２,Ｂｃｌ－ＸＬ,Ｂａｘ调节凋亡的机制之一。     

细胞凋亡中的钙调节

胞质Ca^2 升高是细胞凋亡中Ca^2 调节的经典模式,但近年来有证据表明胞质Ca^2 下降同样能诱导细胞凋亡,目前研究发现,胞内Ca^2 在细胞质,细胞核以及细胞钙库线粒体和内质网的动态平衡破坏和重新分布直接参与细胞凋亡信号的调控,而Bcl-2家族蛋白在细胞凋亡过程的胞内Ca^2 调节及继后的一系列生理效应中发挥特殊作用。细胞凋亡中Ca^2 调节的深入研究不但有助于阐明细胞凋亡的调控机理,同时为相关疾病防治和药物开发提供新的策略。     

细胞凋亡的分子机制

多细胞生物在发生,发展过程中,为了保持正常的生理机能,一部分的细胞发生自发性细胞死亡,这种细胞死亡是被细胞内一系列相关性的分子所调控,并伴随有典型的形态学改变,这种现象被称为细胞凋亡（ａｐｏｐｔｏｓｉｓ）作为一种积极排队生物体内的过剩细胞和有害细胞的机制在个体形态形成,形态改变等发生过程中,成体的恒常性的维持以及生物体的防御等方面发挥作用,此外在许多病理状态下也存在着细胞凋亡,近年的研究已经明确了     

Bcl—2基因家族在调节细胞凋亡中的作用

Ｂｃｌ－２基因家族包含抑制和促进细胞凋亡两类功能相反的蛋白质,在细胞凋亡中发挥重要的调节作用。本文结合近年来的研究进展,综述了Ｂｃｌ－２基因家族中两类蛋白质分子的结构特征、亚细胞分布、相互间的作用方式以及与它们发挥功能的关系,为认识细胞凋亡中复杂的分子调控机制,寻找凋亡紊乱相关疾病中可资利用的药物干预靶点提供了重要启示。     

促细胞凋亡因子Bid蛋白的研究进展

Bid蛋白是Bcl-家族中促凋亡类的蛋白。它具有可被caspase8酶切高控、高效地诱民细胞色素c从线粒体泄漏到胞浆中的功能,从而在细胞凋亡中起着重要的作用,因而倍受人们的重视。Bid蛋白的功能被发现以来,短短几年间,人们从分子生物学、细胞学、结构分析以及利用脂质体模型膜体系等各方面对Bid蛋白进行研究,取得了很大的进展。     

Bcl—2蛋白家族与细胞凋亡

Bcl-2蛋白家族是调节PCD的关键元件,它们受自身基因表达量的高低及蛋白质磷酸化的调控,可分为Bcl-2,Bax与BH3三个亚放。Bcl-2类蛋白阻遏PCD,Bax及BH3类蛋白则促进PCD,它们通过形成同源或异源二聚体,以及与胞内蛋白因子的相互作用来调节PCD,对其分子机制的阐明,有助于众多遗传病研究的突破。     

Bcl—2抑制电离辐射诱发细胞凋亡的线粒体机制探讨

低剂量电离辐射能够诱发细胞凋亡的发生,Ｂｃｌ－２能够抑制多种因素诱发的细胞凋亡,本文报道了Ｂｃｌ－２基因转染细胞克隆对４ＧｙＸ－射线诱发细胞凋亡的影响及其与可能的机制。结果表明,高度表达Ｂｃｌ－２的细胞克隆在７２ｈ内明显抑制了４ＧｙＸ－射线诱发的ＣＨＯ细胞凋亡,进一步的机制探讨表明,Ｂｃｌ－２能够维持或恢复受电离辐射损伤而降低的线粒体膜电位水平,结果提示：Ｂｃｌ－２对低剂量电离辐射诱发的细胞凋亡的     

Bcl—2家族蛋白与细胞凋亡

Bcl 2家族蛋白是在细胞凋亡过程中起关键性作用的一类蛋白质。在线粒体上 ,Bcl 2家族蛋白通过与其他凋亡蛋白的协同作用 ,调控线粒体结构与功能的稳定性 ,发挥着细胞凋亡“主开关”的作用。Bcl 2家族包括两类蛋白质 :一类是抗凋亡蛋白 ,另一类是促凋亡蛋白。在细胞凋亡时 ,Bcl 2家族中的促凋亡蛋白成员发生蛋白质的加工修饰 ,易位到线粒体的外膜上 ,引起细胞色素c、凋亡诱导因子等其他促凋亡因子的释放 ,导致细胞凋亡 ;而平时被隔离在线粒体等细胞器内的该家族的抗凋亡蛋白成员则抑制细胞色素c和凋亡诱导因子等促凋亡因子的释放 ,具有抑制细胞凋亡的功能。但一旦这类抗凋亡蛋白成员与激活的促凋亡蛋白发生相互作用后 ,便丧失了对细胞凋亡的抑制作用 ,造成线粒体等细胞器的功能丧失和细胞器内促凋亡因子的释放 ,导致细胞凋亡。现以Bcl 2家族调控细胞凋亡的最新研究进展为基础 ,对Bcl 2家族成员及其蛋白质结构、分布和调控细胞凋亡的分子机制进行综述。     

滋养层细胞侵袭相关基因表达谱分析

分离收集正常妊娠第8～12周的细胞滋养层细胞和绒毛外滋养层细胞,提取细胞总RNA,制备cRNA探针并与AffymetrixU133plus2.0基因芯片进行杂交,获得正常细胞滋养层细胞和绒毛外滋养层细胞基因表达谱芯片。经计算机分析共筛选到1318个差异表达基因,其中上调基因813个,下调505个。所有差异表达基因按GeneOntoloty功能分类标准进行了功能检索。为胚胎发育早期绒毛外滋养层细胞侵袭的基因调控机制的研究提供了实验基础。     

Influence of maternal smoking on trophoblast apoptosis throughout development: possible involvement of Xiap regulation

Maternal smoking is associated with severe perinatal complications and significant placental pathologies with underlying ultrastructural changes. In this study, we examined the influence of maternal smoking on trophoblast apoptosis throughout development and correlated those findings with changes in expression of X-linked inhibitor of apoptosis protein (Xiap) as well as Fas and Fas ligand (FasL). Trophoblast apoptosis was determined by DNA fragmentation and TUNEL. Protein expression was assessed by Western blotting and immunohistochemistry. Maternal smoking was associated with increased trophoblast apoptosis in the first trimester but decreased trophoblast apoptosis near term. Placental Xiap levels decreased significantly throughout development in nonsmokers (P < 0.05) but remained elevated in smokers. Fas and FasL levels did not vary significantly throughout development nor between groups. However, procaspase-3 levels were significantly increased in smokers at term. Our results suggest that maternal smoking has different effects at different stages of trophoblast differentiation and that this is regulated in part through modulations in placental Xiap expression.     

木犀草素对子痫前期大鼠滋养层细胞凋亡的影响及其机制

目的探讨木犀草素（LUT）对子痫前期（PE）大鼠滋养层细胞凋亡的影响及其机制。 方法取妊娠10 d SD大鼠,按随机数字表法随机分为对照组、模型组、20、40、60 mmol/L LUT （LUT-L、LUT-M、LUT-H）组,每组各12只,模型组和给药组大鼠皮下注射100 mg/（kg·d）亚硝基左旋精氨酸甲酯建立PE大鼠模型,对照组大鼠皮下注射等量生理盐水,每天1次,注射6 d。妊娠16 d的大鼠分别予以20、40、60 mmol/L LUT腹腔注射,对照组、模型组大鼠腹腔注射等量生理盐水,每天1次,注射5 d。测量各组大鼠妊娠10、16、21 d尾动脉血压及24 h尿蛋白水平;妊娠21 d,原位末端标记法（TUNEL）检测滋养层组织细胞凋亡情况,Western blot法检测滋养层组织B淋巴细胞瘤-2 （Bcl-2）、Bcl-2相关X蛋（Bax）、磷脂酰肌醇3-激酶（PI3K）、磷酸化PI3K （p-PI3K）、蛋白激酶B （Akt）、磷酸化AKT （p-Akt）、内皮型一氧化氮合酶（eNOS）和磷酸化eNOS （p-eNOS）蛋白表达量。多组间比较采用单因素方差分析,组间两两比较采用SNK-q检验。 结果妊娠10 d,各组大鼠尾动脉收缩压、舒张压、24 h尿蛋白含量差异无统计学意义;妊娠16 d,与对照组比较,模型组、LUT-L组、LUT-M组、LUT-H组大鼠尾动脉收缩压、舒张压、24 h尿蛋白含量升高（P均< 0.05）;妊娠21 d,与对照组比较,模型组、LUT-L组、LUT-M组、LUT-H组收缩压[（110.33±3.67）比（147.28±4.16）,（131.29±4.31）,（124.46±4.27）,（118.54±4.18）mmHg]、24 h蛋白尿、细胞凋亡率[（1.38±0.34）%,（43.45±3.72）%,（39.21±3.53）%,（27.86±3.41）%,（23.21±3.28）%]和Bax蛋白表达量均升高;Bcl-2、p-PI3K/PI3K （1.06±0.09比0.25±0.02,0.37±0.03,0.57±0.06,0.73±0.08）、p-Akt/Akt（0.87±0.08比0.11±0.01,0.23±0.03,0.56±0.07,0.78±0.06）和p-eNOS/eNOS蛋白表达水平（0.85±0.07比0.09±0.01,0.16±0.02,0.38±0.04,0.69±0.07）均降低（P均< 0.05）。与模型组比较,LUT-L组、LUT-M组、LUT-H组大鼠尾动脉收缩压、舒张压、滋养层组织细胞凋亡率和Bax蛋白表达量降低,Bcl-2、p-PI3K/PI3K、p-Akt/Akt和p-eNOS/eNOS蛋白表达量升高（P均< 0.05）。 结论LUT可抑制PE大鼠滋养层组织细胞凋亡,其机制可能与PI3K/Akt/eNOS信号通路激活,调控凋亡相关蛋白表达有关。     

Paracrine regulation of distinct trophoblast functions in vitro by placental macrophages

In view of the accumulating evidence for paracrine mechanisms regulating trophoblast function, we tested the hypothesis that placental macrophages affect trophoblast activity in a paracrine fashion. Trophoblast was isolated from 17 term placentas (-IP). One aliquot of cells was further immunopurified (+IP) using an HLA class I antibody. This increased the proportion of trophoblast (+IP >97%; -IP ~70%) as identified by rigorous immunocytochemistry. Most (~70%) non-trophoblast cells in -IP were macrophages. The cells were cultured for 5 days with a daily medium change. In addition, +IP cells from seven placentas were cultured with lipopolysaccharide (LPS)-stimulated or -unstimulated macrophage-conditioned media. The concentrations of lactate, trophoblast-specific hormones, human chorionic gonadotropin-# (hCG-#) and human placental lactogen (hPL), of several prostanoids and of endothelin-1 and angiotensin II were determined in the culture media. The accumulated amounts of substances released into the culture media, corrected for the greater proportion of trophoblast in +IP cultures, were on average two- to threefold higher (hCG-#: 18-fold) in +IP than in -IP, with the exception of endothelin-1,2 (no change), angiotensin II (-70%) and 6-keto-prostaglandin-F_1! (-40%). [³H]leucine incorporation into the trichloroacetic acid (TCA)-precipitable pool measured on day 5 was twofold higher in +IP than in -IP. Addition of conditioned media reverted these changes. The data demonstrate that placental macrophages in culture affect trophoblast biosynthetic activity in a paracrine fashion. We conclude that macrophages are important regulators of trophoblast activity.     

TNFalpha-induced apoptosis and integrin switching in human extravillous trophoblast cell line

Differentiation of extravillous trophoblast cells (EVT) to an invasive phenotype plays an essential role in establishing and maintaining feto-placental organization during human pregnancy. A switch in integrin expression occurs during this differentiation and is accompanied by changes in the extracellular matrix (ECM). Alteration of EVT behavior is also modulated by cytokines. To investigate the molecular interactions involved in the EVT differentiation, we examined the effects of cytokines and ECM on the human EVT cell line, TCL1 cells. We found that tumor necrosis factor alpha (TNFalpha) induced apoptosis in TCL1 cells but not in JEG3 cells derived from choriocarcinoma while the addition of interleukin-1beta, leukemia inhibitory factor, or transforming growth factor had no effect on TCL1 cells. This apoptosis was suppressed when TCL1 cells were seeded on fibronectin (Fn), collagen type I (C1), collagen type IV (C4), or laminin (Ln). Wortmannin, a specific PI3 kinase inhibitor, inhibited this suppression. Spreading assays and adhesion blocking assays indicated that TCL1 cells express integrin-alpha5 and -alpha6 and beta1 and beta4 subunits. Adhesion on Fn is mediated by alpha5beta1, and adhesion on C1, C4, or Ln is mediated by alpha6beta1 integrins. TNFalpha suppressed alpha6 integrin expression and enhanced alpha1 integrin expression in a dose-dependent manner. In addition, aggregation of beta1 subunits on C4 was detected after addition of TNFalpha. Taken together, these results suggest that TNFalpha and ECM, through activation of PI3 kinase mediated by beta1 integrin signaling, might collaboratively regulate differentiation of trophoblast cells through integrin signaling in establishing and maintaining successful pregnancy.     

热激蛋白对细胞凋亡的调节作用

细胞凋亡是生物发育过程中或在正常生理状态下清除衰老及受损细胞的一种普遍现象。细胞凋亡的发生受胞外或胞内的多种刺激源所诱导,其中热激蛋白是细胞凋亡的调控因子之一。本文着重讨论了热激蛋白在细胞凋亡调节中所发挥的作用。     

Proteolytic regulation of apoptosis

Much of the proteolysis that occurs during apoptosis is directed by caspases, a family of related cysteinyl proteases. A relatively small number of cellular proteins are targeted by caspases, yet their function is dramatically affected and apoptosis is triggered. Other proteases, such as granzymes and calpain, are also involved in the apoptotic signaling process, but in a much more cell type- and/or stimulus type-specific manner. At least three distinct caspase-signaling pathways exist; one activated through ligand-dependent death receptor oligomerization, the second through mitochondrial disruption, and the third through stress-mediated events involving the endoplasmic reticulum. These pathways also appear to interact to amplify weak apoptotic signals and shorten cellular execution time. Finally, defects in caspases contribute to autoimmune disease, cancer and certain neurological disorders.     

Negative regulation of apoptosis in yeast

In recent years, yeast has been proven to be a useful model organism for studying programmed cell death. It not only exhibits characteristic markers of apoptotic cell death when heterologous inducers of apoptosis are expressed or when treated with apoptosis inducing drugs such as hydrogen peroxide (H(2)O(2)) or acetic acid, but contains homologues of several components of the apoptotic machinery identified in mammals, flies and nematodes, such as caspases, apoptosis inducing factor (AIF), Omi/HtrA2 and inhibitor-of-apoptosis proteins (IAPs). In this review, we focus on the role of negative regulators of apoptosis in yeasts. Bir1p is the only IAP protein in Saccharomyces cerevisiae and has long been known to play a role in cell cycle progression by acting as kinetochore and chromosomal passenger protein. Recent data established Bir1p's protective function against programmed cell death induced by H(2)O(2) treatment and in chronological ageing. Other factors that have a direct or indirect influence on intracellular levels of reactive oxygen species (ROS) and thus lead to apoptosis if they are misregulated or non-functional will be discussed.