Latent role of in vitro Pb exposure in blocking Aβ clearance and triggering epigenetic modifications

Both β-amyloid (Aβ) catabolism and epigenetic regulation play critical roles in the onset of neurodegeneration. The latter also contribute to Pb neurotoxicity. The present study explored the role of epigenetic modifiers and Aβ degradation enzymes in Pb-induced latent effects on Aβ overproduction in vitro. Our results indicated that in SH-SY5Y cells exposed to Pb, the expression of NEP and IDE remained declined during the recovery period, accompanied with abnormal increase of Aβ_1-42 and amyloid oligomer. A disruption of selective global post-translational histone modifiers including the decrease of H3K9ac and H4K12ac and the induction of H3K9me2 and H3K27me2 dose dependently was also showed in recovery cells. Moreover, histone deacetylase inhibitor VPA could attenuate latent Aβ accumulation and HDAC activity induced by Pb, which might be by regulating the expression of NEP and IDE epigenetically. Overall, our results suggest sustained reduction of NEP and IDE expression in response to Pb sensitizes recovery SH-SY5Y cells to Aβ accumulation; however, administration of VPA is demonstrated to be beneficial in modulating Aβ clearance.     

The effects of selected inhibitors of histone modifying enzyme on C6 glioma cells

BackgroundAberrant epigenetic histone modifications are implicated in cancer pathobiology, therefore histone modifying enzymes are emerging targets for anti-cancer therapy. There is a few evidence for deregulation of the histone modifying enzymes in glioblastomas. Glioma treatment is a clinical challenge due to its resistance to current therapies.MethodsThe effect of selected inhibitors on epigenetic modifications and viability of glioma C6 cells were studied using immunofluorescence and MTT metabolism test.ResultsWe found that VPA and TSA increase histone H4 acetylation in glioma cells, while chaetocin and BIX01294 at low concentrations reduce H3K9me3, and 3DZNep decreases H3K27me3. Long-term treatment with some epigenetic inhibitors affects viability of glioma cells.ConclusionsWe established the concentrations of selected inhibitors which in C6 glioma cells inhibit the enzyme activity, but do not decrease cell viability, hence allow to study the role of histone modifications in C6 glioma biology.     

组蛋白H3K36me3与缺血再灌注诱导小鼠急性肾损伤的相关性研究

目的:研究组蛋白H3K36三甲基化(H3K36me3)在缺血再灌注(IR)诱导的急性肾损伤(AKI)小鼠肾组织中的表达,分析其与肾组织中N-赖氨酸甲基转移酶SMYD2及肾损伤程度的相关性,为临床治疗IR-AKI提供新的靶点。方法:30只ICR小鼠随机分为IR组(n=15)和假手术组(sham组,n=15),应用微动脉夹夹闭双侧肾蒂45 min构建IR模型,于造模后24 h收取小鼠血清和肾组织标本。生化法检测血尿素氮(BUN)和血清肌酐(SCr);HE染色检测肾组织病理学改变;免疫组织化学(IHC)染色检测肾组织中NGAL和cleaved caspase-3的表达;Western blot检测肾组织NGAL、SMYD2、H3K36me3、p-P53、P53、cleaved caspase-3、Bax、Bcl-2、STAT3、p-STAT3、JNK和p-JNK1/2/3蛋白的水平。应用Pearson相关法分析H3K36me3与肾组织SMYD2及NGAL的相关性。结果:与sham组相比,IR组BUN和SCr水平显著升高(P<0.05);HE染色显示,IR组肾小管上皮细胞水肿、脱落、坏死,刷状缘脱落,管腔内大量细胞碎屑残留;IHC染色显示,IR组肾小管上皮细胞中NGAL和cleaved caspase-3明显增多;Western blot结果显示,IR组NGAL、SMYD2、H3K36me3、p-P53、cleaved caspase-3、Bax、STAT3、p-STAT3、JNK及p-JNK1/2/3蛋白的水平明显上调(P<0.05),Bcl-2蛋白水平明显下调(P<0.05);肾组织H3K36me3同SMYD2和NGAL的水平均呈显著正相关。结论:H3K36me3与IR-AKI小鼠肾损伤程度及肾组织SMYD2均密切相关,H3K36me3表达上调可能与STAT3和JNK信号通路活化共同参与调控IR-AKI的发生发展。     

组蛋白甲基化与lncRNAs的表达调控

LncRNAs是长度超过200 nt非编码蛋白质的RNA分子,并参与细胞内多种调控过程.LncRNA在发育和基因表达中发挥着复杂精确的调控功能,补充解释了基因组复杂性的生物意义,同时也使人们重新认识了生命过程中基因表达调控网络的复杂性.LncRNA参与了X染色体沉默、基因组印记、染色质修饰、转录激活、转录干扰以及核内运输等多种重要的调控过程.组蛋白修饰是基因表达调控的重要形式,尤其是组蛋白甲基化的调控作用.研究发现组蛋白甲基化对基因异常表达的调控参与多种肿瘤的发生.组蛋白去甲基化酶的发现又提出了一种新的理念,即组蛋白甲基化对lncRNA表达调控作用,这将是基因表达调控研究的新领域.     

儿童H3K27M突变型弥漫性中线胶质瘤的MRI表现

目的:探讨儿童H3K27M突变型弥漫性中线胶质瘤的MRI特征.方法:回顾性分析9例经手术病理证实的儿童H3K27M突变型弥漫性中线胶质瘤的临床资料及MRI表现.结果:9例病变均位于脑干,8例呈不规则形,1例呈类圆形,边界均清楚;T1WI以低或稍低信号为主(6例混杂低信号,3例稍低信号),T2WI以高或稍高信号为主(6例...     

组蛋白去乙酰化酶抑制剂及PPARγ激动剂在甲状腺肿瘤治疗中的作用

手术、放射性碘及促甲状腺激素抑制治疗等常规疗法对低分化及未分化甲状腺肿瘤疗效不佳。组蛋白去乙酰化酶（HDAC）作为调控基因转录的关键蛋白酶,其功能异常与肿瘤的发生、发展密切相关。过氧化物酶体增殖物活化受体（PPAR）γ属于激素核受体超家族之一,与细胞的生长、分化密切相关。近来发现HDAC抑制剂及PPARγ激动剂可通过抑制肿瘤细胞增殖、促进其凋亡、诱导其再分化治疗血液系统肿瘤及包括甲状腺肿瘤在内的多种实体瘤,为低分化及未分化甲状腺肿瘤的治疗提供了新思路。     

肿瘤表观遗传学研究进展

对肿瘤研究的不断深入使人们认识到几乎所有人类肿瘤都是由表观遗传学异常与基因改变共同引起并促进其演变的.表观遗传学改变主要包括DNA甲基化改变和组蛋白修饰,这两种调控模式本身及之间的相互作用网络可导致印记丢失,染色质重塑,非必需重复序列的转录、基因的异常活化以及抑制肿瘤发生和演进基因的异常沉默等,在异常的克隆性增生和癌性增生的级联事件起始中发挥重要作用,在酵母模型中的研究更深入的理解了肿瘤干细胞的定义以及引起肿瘤的相关分子机制.表观遗传学的研究为进一步了解肿瘤的各种特性,优化肿瘤的早期诊断,改善肿瘤的预后提供了新的策略.