Histone deacetylases 1 and 2 control the progression of neural precursors to neurons during brain development

The molecular mechanism by which neural progenitor cells commit to a specified lineage of the central nervous system remains unknown. We show that HDAC1 and HDAC2 redundantly control neuronal development and are required for neuronal specification. Mice lacking HDAC1 or HDAC2 in neuronal precursors show no overt histoarchitectural phenotypes, whereas deletion of both HDAC1 and HDAC2 in developing neurons results in severe hippocampal abnormalities, absence of cerebellar foliation, disorganization of cortical neurons, and lethality by postnatal day 7. These abnormalities in brain formation can be attributed to a failure of neuronal precursors to differentiate into mature neurons and to excessive cell death. These results reveal redundant and essential roles for HDAC1 and HDAC2 in the progression of neuronal precursors to mature neurons in vivo.     

干细胞因子SOX2在肺癌中的表达及意义

目的通过检测肺癌组织中干细胞因子SOX2的表达水平,了解其表达与肺癌病理特征之间的关系。方法应用免疫组织化学方法检测112例肺癌患者术后癌组织标本中SOX2蛋白的表达水平,探讨其与肺癌临床病理特征及发生发展的关系。结果 SOX2蛋白在肺癌组织中的阳性表达率为95.54%,在正常肺组织中无表达。其表达水平与肺癌的分化程度、有无淋巴结转移有关,而与患者的性别、年龄、组织类型等无关。结论 SOX2将可能成为肺癌临床诊断和病理分型的重要检测因子。     

miR-140靶向调控SOX2在结肠癌中的作用机制研究

目的 分析miR-140在结肠癌中的作用机制.方法 qRT-PCR检测miR-140在结肠癌细胞和组织中的表达;CCK8法、细胞划痕实验检测miR-140对结肠癌HT29细胞增殖和迁移的影响.TargetScan筛选miR-140的潜在靶基因并通过双荧光素酶报告基因试验进行验证;采用qRT-PCR和Western bl...     

Culture of leukocyte-derived cells from human peripheral blood: Increased expression of pluripotent genes OCT4, NANOG,SOX2, self-renewal gene TERT and plasticity

There are few stem cells in human peripheral blood (PB). Increasing the population and plasticity of stem cells in PB and applying it to regenerative medicine require suitable culture methods. In this study, leukocyte populations 250 mL of PB were collected using a blood separator before that were cultured in optimal cell culture medium for 4 to 7 days. After culturing, stemness characteristics were analyzed, and red blood cells were removed from the cultured cells. In our results, stemness markers of the leukocyte populations Sca-1⁺ CD45⁺, CD117⁺ CD45⁺, and very small embryonic-like stem cells CD34⁺ Lin⁻ CD45⁻ and CXCR4⁺ Lin⁻ CD45⁻ were significantly increased. Furthermore, the expression of stem cell genes OCT4 (POU5F1), NANOG, SOX2, and the self-renewal gene TERT was analyzed by quantitative real-time polymerase chain reaction in these cells, and it showed a significant increase. These cells could be candidates for multi-potential cells and were further induced using trans-differentiation culture methods. These cells showed multiple differentiation potentials for osteocytes, nerve cells, cardiomyocytes, and hepatocytes. These results indicate that appropriate culture methods can be applied to increase expression of pluripotent genes and plasticity. Leukocytes of human PB can be induced to trans-differentiate into pluripotent potential cells, which will be an important breakthrough in regenerative medicine.     

Space radiation-induced inhibition of neurogenesis in the hippocampal dentate gyrus and memory impairment in mice: ameliorative potential of the melatonin metabolite, AFMK

Evaluation of potential health effects from high energy charged particle radiation exposure during long duration space travel is important for the future of manned missions. Cognitive health of an organism is considered to be maintained by the capacity of hippocampal precursors to proliferate and differentiate. Environmental stressors including irradiation have been shown to inhibit neurogenesis and are associated with the onset of cognitive impairments. The present study reports on the protective effects of N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK), a melatonin metabolite, against high energy charged particle radiation-induced oxidative damage to the brain. We observed that radiation exposure (2.0 Gy of 500 MeV/nucleon (56)Fe beams, a ground-based model of space radiation) impaired the spatial memory of mice at later intervals without affecting the motor activities. AFMK pretreatment significantly ameliorated these neurobehavioral ailments. Radiation-induced changes in the population of immature and proliferating neurons in the dentate gyrus were localized using anti-doublecortin (Dcx) and anti-Ki-67 expression. AFMK pretreatment significantly inhibited the loss of Dcx and Ki-67 positive cells. Moreover, AFMK pretreatment ameliorated the radiation-induced augmentation of protein carbonyls and 4-hydroxyalkenal + malondialdehyde (MDA + HAE) in the brain and maintained the total antioxidant capacity of plasma and nonprotein sulfhydryl contents in brain.     

Brief Report: Adenosine A2A receptor blockade prevents cisplatin-induced impairments in neurogenesis and cognitive function

Chemotherapy-induced cognitive impairment (CICI) has emerged as a significant medical problem without therapeutic options. Using the platinum-based chemotherapy cisplatin to model CICI, we revealed robust elevations in the adenosine A_2A receptor (A_2AR) and its downstream effectors, cAMP and CREB, by cisplatin in the adult mouse hippocampus, a critical brain structure for learning and memory. Notably, A_2AR inhibition by the Food and Drug Administration–approved A_2AR antagonist KW-6002 prevented cisplatin-induced impairments in neural progenitor proliferation and dendrite morphogenesis of adult-born neurons, while improving memory and anxiety-like behavior, without affecting tumor growth or cisplatin’s antitumor activity. Collectively, our study identifies A_2AR signaling as a key pathway that can be therapeutically targeted to prevent cisplatin-induced cognitive impairments.     

A PHD-polycomb repressive complex 2 triggers the epigenetic silencing of FLC during vernalization

Vernalization, the acceleration of flowering by winter, involves cold-induced epigenetic silencing of Arabidopsis FLC. This process has been shown to require conserved Polycomb Repressive Complex 2 (PRC2) components including the Su(z)12 homologue, VRN2, and two plant homeodomain (PHD) finger proteins, VRN5 and VIN3. However, the sequence of events leading to FLC repression was unclear. Here we show that, contrary to expectations, VRN2 associates throughout the FLC locus independently of cold. The vernalization-induced silencing is triggered by the cold-dependent association of the PHD finger protein VRN5 to a specific domain in FLC intron 1, and this association is dependent on the cold-induced PHD protein VIN3. In plants returned to warm conditions, VRN5 distribution changes, and it associates more broadly over FLC, coincident with significant increases in H3K27me3. Biochemical purification of a VRN5 complex showed that during prolonged cold a PHD-PRC2 complex forms composed of core PRC2 components (VRN2, SWINGER [an E(Z) HMTase homologue], FIE [an ESC homologue], MSI1 [p55 homologue]), and three related PHD finger proteins, VRN5, VIN3, and VEL1. The PHD-PRC2 activity increases H3K27me3 throughout the locus to levels sufficient for stable silencing. Arabidopsis PHD-PRC2 thus seems to act similarly to Pcl-PRC2 of Drosophila and PHF1-PRC2 of mammals. These data show FLC silencing involves changed composition and dynamic redistribution of Polycomb complexes at different stages of the vernalization process, a mechanism with greater parallels to Polycomb silencing of certain mammalian loci than the classic Drosophila Polycomb targets.     

Bcl-2、Fas和Bax凋亡调控基因在限食和脑老化小鼠海马神经元中的表达

目的 通过细胞凋亡调控基因Bcl-2、Fas和Bax在限食及脑老化小鼠海马神经元中的表达,研究限食与脑老化的关系.方法 3月龄ICR雄性小鼠40只,随机分为4组:脑老化模型组、脑老化模型限食组、限食对照组、对照组,每组10只.10 w后进行为期7 d Morris水迷宫实验,实验完毕后进行Bcl-2、Fas和Bax免疫组织化学染色.结果 ①Fas、Bax阳性神经元数目脑老化模型组显著高于脑老化模型限食组、限食对照组显著低于对照组;与此相反,Bcl-2阳性神经元数目在脑老化模型限食组显著高于脑老化模型组,限食对照组显著高于对照组.②Morris水迷宫实验测试:脑老化模型组逃避潜伏期显著大于其他各组;撤台后小鼠的记忆性搜台游泳路程结果各组小鼠间均无显著差异.结论 限食可明显降低脑内凋亡相关基因Fas、Bax的表达,同时上调抗凋亡相关基因Bcl-2的表达,从而发挥抗脑细胞凋亡及防止脑老化性学习能力下降的作用.     

Haem-regulated eIF2alpha kinase is necessary for adaptive gene expression in erythroid precursors under the stress of iron deficiency

Haem-regulated eIF2alpha kinase (HRI) is essential for the regulation of globin gene translation and the survival of erythroid precursors in iron/haem deficiency. This study found that that in iron deficiency, fetal definitive erythropoiesis is inhibited at the basophilic erythroblast stage with increased proliferation and elevated apoptosis. This hallmark of ineffective erythropoiesis is more severe in HRI deficiency. Microarray gene profiling analysis showed that HRI was required for adaptive gene expression in erythroid precursors during chronic iron deficiency. The number of genes with expression affected more than twofold increased, from 213 in iron deficiency and 73 in HRI deficiency, to 3135 in combined iron and HRI deficiencies. Many of these genes are regulated by Gata1 and Fog1. We demonstrate for the first time that Gata1 expression in developing erythroid precursors is decreased in iron deficiency, and is decreased further in combined iron and HRI deficiencies. Additionally, Fog1 expression is decreased in combined deficiencies, but not in iron or HRI deficiency alone. Our results indicate that HRI confers adaptive gene expression in developing erythroblasts during iron deficiency through maintaining Gata1/Fog1 expression.     

去除穿膜区序列的线粒体融合素2基因通过线粒体凋亡路径促进大鼠血管平滑肌细胞凋亡

目的 研究去除穿膜区序列的大鼠线粒体融合素2(tMfn2)基因对大鼠血管平滑肌细胞(VSMC)凋亡的影响及其相关的信号通路.方法 用携带tMfn2基因和线粒体融合素2(Mfn2)基因的重组腺病毒(Adv-tMfn2和Adv-Mfn2)感染VSMC.采用流式细胞术、细胞凋亡ELISA、TUNEL染色等方法检测tMfn2对VSMC凋亡的影响.Western blot分析磷酸化蛋白激酶B(p-Akt)以及线粒体凋亡路径中B细胞淋巴瘤/白血病-2蛋白(Bcl-2)、Bcl-2相关的X蛋白(Bax)、有活性的天冬氨酸特异-半胱氨酸蛋白酶9(cleaved caspase-9)的表达变化.结果 流式细胞仪检测和ELISA结果表明.tMfn2促VSMC凋亡的作用显著强于Mfn2,且呈时间依赖性[72 h凋亡率分别为(79.2±0.12)%和(65.0±1.2)%,P<0.01].TUNEL染色发现tMfn2组的凋亡细胞明显多于Mfn2组(P<0.01).Western blot结果显示,tMfn2和Mfn2组中p-Akt水平均明显降低,但前者作用更显著(P<0.01).进一步检测线粒体凋亡路径中的相关蛋白,tMfn2组的Bax蛋白表达显著升高、Bcl-2蛋白表达显著降低,且cleaved caspase-9的活性明显增强,较Mfn2诱导凋亡的作用更强(P<0.01).结论 与Mfn2相比,tMfn2促进VSMC凋亡的作用更强,其机制与抑制Akt磷酸化并激活线粒体凋亡途径有关.