IAP家族抑制衰老的骨髓间充质干细胞的凋亡

目的:探讨衰老的大鼠骨髓间充质干细胞凋亡抗性是否增加且是否通过凋亡抑制蛋白(IAP)家族介导。方法:用DMEM/F12中加入10%胎牛血清(FBS)的完全培养基培养大鼠骨髓间充质干细胞(BMSC)至第三代,使用D-半乳糖(D-gal)诱导成衰老的BMSC并用β-半乳糖苷酶染色做衰老鉴定。用肿瘤坏死因子α(TNF-α)和环己酰亚胺(CHX)共同处理正常对照组与衰老组的BMSC,通过贴壁细胞计数统计其生存率,并通过蛋白印迹法检测两组细胞中Cleaved PARP、Cleaved Caspase3蛋白、IAP家族成员c-IAP1、c-IAP2、XIAP以及衰老相关标志蛋白的水平。再用IAP抑制剂AT-406处理衰老的细胞,CCK-8检测处理组以及未处理组细胞的细胞活力。最后用凋亡抑制剂z-VAD-fmk和AT-406共同处理正常对照组与衰老组细胞,观察z-VAD-fmk能否减少IAP蛋白被抑制后所引起的细胞死亡。结果:与正常对照组相比,衰老的BMSC中由TNF-α和CHX共同诱导引起的细胞死亡数明显减少,凋亡标志物Cleaved PARP和Cleaved Caspase3蛋白的水平降低,而IAP家族成员c-IAP1、c-IAP2和XIAP的蛋白水平升高。用AT-406处理衰老BMSC后细胞的死亡数明显高于未处理的衰老BMSC组,通过z-VAD-fmk抑制凋亡通路后,AT-406处理的衰老细胞的死亡数减少。结论:衰老BMSC通过升高IAP家族蛋白水平从而提高对凋亡的抵抗能力。     

不同年龄大鼠血清对骨髓间充质干细胞衰老影响的实验研究

制备成年(8～12周龄)和老年(64～72周龄)SD大鼠血清,实验随机分为两组:年轻血清组和老年血清组,分别采用成年和老年SD大鼠血清培养成年MSCs 36小时后,衰老相关β-半乳糖苷酶和活性氧染色观察细胞衰老,MTT法检测细胞增殖,AO/EB法和Hoechst 33342染色法观察细胞凋亡及存活情况。免疫细胞化学和Western blot法检测衰老相关蛋白γ-H2A.X、p53表达,RT-PCR法观察p53、p21 mRNA表达。结果发现,与年轻血清组相比,老年血清组MSCs衰老细胞数明显增加((96.2±24.1)/500细胞vS(30.8±8.2)/500细胞,P<0.01)、增殖能力减弱,凋亡率升高,γ-H2A.X、p53蛋白表达水平升高,p53、p21 mRNA表达升高。这些结果说明、老年SD大鼠血清可促进MSCs发生衰老变化,并抑制MSCs增殖及存活能力,这一作用可能与DNA损伤反应和p53/p21信号通路有关。     

miRNAs与衰老相关信号通路的研究进展

miRNAs是一类负调控基因表达的内源性非编码小分子RNA,在细胞衰老过程中发挥重要作用. 细胞衰老是指可增殖细胞在各种应激下出现细胞周期阻滞,并且丧失增殖能力,进入一种不可逆的、相对稳定的状态. p53、p21、p16、SIRT1、胰岛素/IGF-1及mTOR等蛋白是衰老相关信号通路中的重要分子,参与细胞衰老过程. 研究表明,miRNAs可以通过调控这些衰老相关蛋白所在的信号通路,促进或延缓细胞衰老. 本文综述细胞衰老相关的miRNAs,以及它们对衰老相关信号通路的影响,为深化认识衰老和衰老相关疾病的分子机制奠定基础.     

齐墩果酸对自然衰老大鼠睾丸DNA损伤保护作用及机制研究

探讨齐墩果酸(Oleanolic Acid,OA)对自然衰老大鼠睾丸DNA损伤的保护作用及其可能机制。将30只SPF级18月龄SD大鼠随机分为三组:自然衰老组、OA低、高剂量组,每组10只,另取10只3月龄大鼠作为青年对照组。OA低、高剂量组分别灌胃给予OA 5、25 mg/kg,自然衰老组和青年对照组给予生理盐水,每周灌胃6天,周日不给药,连续给药6个月。末次给药后禁食不禁水12 h,称重,麻醉后处死大鼠,快速取出睾丸组织。HE染色观察睾丸组织形态变化,免疫组织化学法检测DNA损伤相关蛋白53BP1、ATR的表达,Western Blot检测睾丸组织中衰老相关蛋白p21和DNA损伤相关蛋白γ-H2AX、Chk1、p-p53的表达水平。HE结果表明,OA能显著改善增龄所致的睾丸组织形态变化;与青年对照组相比,自然衰老组睾丸组织DNA损伤标志蛋白γ-H2AX表达水平明显升高,而给予OA干预后其表达显著降低;此外,与青年对照组比较,自然衰老组睾丸组织中衰老相关蛋白p21的表达显著增高,DNA损伤相关蛋白53BP1、ATR的阳性灶点数及其下游Chk1、p-p53的蛋白表达明显升高,OA低、高剂量组均能显著降低上述蛋白的表达。以上结果表明OA对自然衰老大鼠睾丸组织DNA损伤有较好的保护作用,机制与调节ATR/Chk1/P53信号通路有关。     

5-氮胞苷对转化后间充质干细胞增殖、衰老及p16~(INK4a)表达的影响

目的观察5-氮胞苷对体外自发转化的间充质干细胞增殖、衰老及p16INK4a基因表达的影响。方法采用细胞计数、SA-β-gal染色、Western Blot和重硫酸盐修饰后测序(BSP)检测体外自发转化的大鼠间充质干细胞在不同浓度5-氮胞苷处理后增殖、衰老、p16INK4a表达及p16INK4a基因启动子区CpG岛甲基化水平的变化。结果细胞计数显示5-氮胞苷可剂量依赖性地抑制转化后间充质干细胞的增殖,但增殖受抑的细胞SA-β-gal染色仍呈阴性。BSP及Western Blot分析显示:转化后间充质干细胞p16INK4a基因启动子区CpG岛呈现高水平甲基化(87.30±2.39%)。5-氮胞苷可在一定程度上降低该基因的甲基化,使p16INK4a表达得以部分恢复;但即使是高浓度高达100μmol/L,5-氮胞苷也只能使p16INK4a基因甲基化降低到46.20±1.65%。结论 5-氮胞苷可显著抑制转化后间充质干细胞的增殖,但并不能促使这些细胞重新恢复衰老状态;其原因是5-氮胞苷单独作用不足以完全解除p16INK4a基因启动子区DNA的高甲基化。     

主要干性基因与衰老相关基因表达水平的相互拮抗关系

目前广泛地利用传统的体细胞衰老理论和方法对成体干细胞衰老进行研究,忽视了成体干细胞特有的自我更新功能和相应的干性基因的作用.干性基因的下调可能是导致间充质干细胞衰老的主要原因.通过查阅相关资料发现主要干性基因与衰老相关基因表达水平的相互拮抗关系,这体现在以下4个方面:a.干细胞衰老伴随着干性基因的下调;b.干性基因表达抑制细胞的衰老;c.干性基因抑制衰老相关基因的表达;d.抑制衰老相关基因促进干性基因的表达.干性基因与衰老相关基因的表达水平存在相互拮抗关系,这为成体干细胞衰老可能源于成体干细胞的干性降低的观点提供了坚实的分子基础.     

DNA损伤监测及修复相关酶与细胞衰老

衰老是细胞的重要生命现象之一,衰老假说之一认为细胞中残留DNA损伤的积累可加速细胞的衰老.因此,细胞内DNA损伤监测及修复系统的正常运行与细胞衰老调控密切相关,DNA损伤监测及修复相关酶如PARP、DNA-PK、ATM、p53等在细胞衰老中的调控作用日益受到广泛关注.研究这些蛋白质分子间的相互作用及其在细胞衰老过程中的调控功能,有利于揭示DNA损伤应激、损伤修复调控与细胞衰老之间的内在联系,为抗衰老研究及从衰老角度治疗肿瘤提供新的思路.     

脱细胞神经移植物对骨髓间充质干细胞的诱导分化

目的探讨脱细胞神经移植物诱导大鼠骨髓间充质干细胞分化为施旺细胞样细胞的可行性。方法将分离纯化的SD大鼠骨髓间充质干细胞进行体外培养扩增,行表型鉴定后,取第5代细胞,诱导组采用脱细胞神经移植物匀浆进行诱导,非诱导组加入等量无血清培养基,倒置相差显微镜观察诱导后细胞形态变化,免疫细胞化学染色检测诱导后细胞S-100,神经胶质纤维酸性蛋白(glial fibrillary acidic protein GFAP)的表达情况。结果BMSCs表型鉴定为CD44+、CD54+、CD34-,免疫细胞化学染色GFAP、S-100的阳性表达率分别为为(42±4)%和(64±5)%。结果 脱细胞神经移植物可诱导骨髓间充质干细胞分化为施旺细胞样细胞。     

辐射诱导细胞衰老的机制研究进展

辐射诱导细胞衰老属于胁迫诱导的早熟性衰老。研究表明在外界应激条件下,衰老的细胞会出现肿胀、增殖减弱、周期受阻、β-半乳糖苷酶活性增强、p53-p21和p16-RB信号通路以及调控衰老的miRNAs被激活等特点。本文综述了辐射诱导细胞衰老的过程,并着重介绍了细胞衰老的两条信号通路p53-p21和p16-RB以及miRNAs对细胞的调控,为进一步的基础研究提供理论参考。     

高氧胁迫下Peroxiredoxin2蛋白的细胞保护作用的研究

衰老和凋亡是细胞的两个重要生理过程,一直以来都是细胞生物学领域研究的热点。Peroxiredoxin 2(Prdx2)蛋白是过氧化物酶的其中一个亚型,分布于细胞质中。为了研究它在高氧条件诱导的细胞衰老及凋亡中的保护作用,我们分别将大鼠来源的Prdx2基因转染进人间充质干细胞(Human mesenchymal stem cells,hMSCs)和HEK293T细胞中,并建立了稳定表达Prdx2蛋白的HEK293T细胞系,利用SA-β-gal染色(Senescence-Associated β-Galactosidase Assay)、TUNEL染色及磷酸化p53蛋白的免疫印迹来检测高氧处理后细胞的衰老和凋亡情况。实验结果表明,高氧处理细胞后,转染了Prdx2的hMSCs和HEK293T细胞其衰老和凋亡率与对照组相比都有较为明显的减少,暗示Prdx2蛋白在细胞抵抗氧化损伤中发挥了重要作用。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细