Activation of sirtuin 1/3 improves vascular hyporeactivity in severe hemorrhagic shock by alleviation of mitochondrial damage

Vascular hyporeactivity is one of the major causes responsible for refractory hypotension and associated mortality in severe hemorrhagic shock. Mitochondrial permeability transition (mPT) pore opening in arteriolar smooth muscle cells (ASMCs) is involved in the pathogenesis of vascular hyporeactivity. However, the molecular mechanism underlying mitochondrial injury in ASMCs during hemorrhagic shock is not well understood. Here we produced an in vivo model of severe hemorrhagic shock in adult Wistar rats. We found that sirtuin (SIRT)1/3 protein levels and deacetylase activities were decreased in ASMCs following severe shock. Immunofluorescence staining confirmed reduced levels of SIRT1 in the nucleus and SIRT3 in the mitochondria, respectively. Acetylation of cyclophilin D (CyPD), a component of mPT pore, was increased. SIRT1 activators suppressed mPT pore opening and ameliorated mitochondrial injury in ASMCs after severe shock. Furthermore, administration of SIRT1 activators improved vasoreactivity in rats under severe shock. Our data suggest that epigenetic mechanisms, namely histone post-translational modifications, are involved in regulation of mPT by SIRT1/SIRT3- mediated deacetylation of CyPD. SIRT1/3 is a promising therapeutic target for the treatment of severe hemorrhagic shock.     

狼疮性肾炎患者血浆组蛋白乙酰化酶和组蛋白去乙酰化酶表达及其与IL-6、INF-γ的关系

目的 研究狼疮性肾炎(LN)患者血浆组蛋白乙酰化酶(HAT)、组蛋白去乙酰化酶(HDAC)表达水平,分析其与LN活动性、炎性细胞因子等的关系,探究组蛋白乙酰化酶在LN发病机制中的作用.方法 共收入正常对照组(N组,8例),狼疮性肾炎患者组(18例).狼疮性肾炎组分为非活动期(Ⅰ组,8例),活动期(A组,10例).采用ELISA检测血浆HAT、HDAC、IL-6、INF-γ水平;采用直线相关性分析HAT、HDAC表达与IL-6、INF-γ相关性.结果 Ⅰ组患者血浆HAT含量低于N组,但差异无统计学意义,A组患者HAT含量明显低于N组,差异有统计学意义[(9.74±3.67)vs(15.32±3.32),P＜0.05],但Ⅰ组与A组患者比较,差异无统计学意义;与N组比较,Ⅰ组和A组患者中血浆HDAC含量明显降低[(6.75±2.05)vs (17.08±6.46),P＜0.05;(4.53±3.62)vs(17.08±6.46),P＜0.05],但两组之间比较差异无统计学意义.Ⅰ组和A组患者血浆IL-6、INF-γ均明显高于N组,A组患者血浆中IL-6、INF-γ均明显高于Ⅰ组.相关性分析,发现HAT、HDAC与IL-6呈负相关(r分别为-0.532和-0.665);而HAT、HDAC与INF-γ呈负相关(r分别为-0.621和-0.720).结论 LN患者血浆HDAC含量、活动期患者HAT低于正常人群,与IL-6、INF-γ呈负相关,HAT、HDAC可能影响IL-6、INF-γ等细胞因子水平参与LN的发病.     

Deacetylation of Chitosan: Material Characterization and in vitro Evaluation via Albumin Adsorption and Pre-Osteoblastic Cell Cultures

Degree of deacetylation (DDA) and molecular weight (MW) of chitosans are important to their physical and biological properties. In this study, two chitosans, HS (DDA = 73.3%) and AT (DDA = 76.8%), were deacetylated with 45% sodium hydroxide under nitrogen atmosphere at 80 °C or 90 °C for up to 120 min, to obtain two series of chitosans. The polymers produced were characterized for MW by gel permeation chromatography, DDA by titration and UV-vis methods, and crystallinity, hydrophilicity and thermal stability by X-ray diffraction, water contact angle and differential scanning calorimetry respectively. Films, made by solution casting in dilute acetic acid at ambient conditions, were evaluated for biological activity by albumin adsorption and the attachment and growth of a pre-osteoblast cell line. Chitosans with between 80–93% DDA’s (based on titration) were reproducibly obtained. Even though deacetylation under nitrogen was supposed to limit chain degradation during decetylation, MW decreased (by maximum of 37.4% of HS and 63.0% for AT) with increasing deacetylation reaction time and temperature. Crystallinity and decomposition temperature increased and water contact angles decreased with processing to increase DDA. Significantly less albumin was absorbed on films made with 93% DDA chitosans as compared with the original materials and the AT chitosans absorbed less than the HS chitosans. The cells on higher DDA chitosan films grew faster than those on lower DDA films. In conclusion, processing conditions increased DDA and influenced physicochemical and biological properties. However, additional studies are needed to unambiguously determine the influence of DDA or MW on in vitro and in vivo performance of chitosan materials for bone/implant applications.     

Subnuclear partitioning of rRNA genes between the nucleolus and nucleoplasm reflects alternative epiallelic states

Eukaryotes can have thousands of 45S ribosomal RNA (rRNA) genes, many of which are silenced during development. Using fluorescence-activated sorting techniques, we show that active rRNA genes in Arabidopsis thaliana are present within sorted nucleoli, whereas silenced rRNA genes are excluded. DNA methyltransferase (met1), histone deacetylase (hda6), or chromatin assembly (caf1) mutants that disrupt silencing abrogate this nucleoplasmic–nucleolar partitioning. Bisulfite sequencing data indicate that active nucleolar rRNA genes are nearly completely demethylated at promoter CGs, whereas silenced genes are nearly fully methylated. Collectively, the data reveal that rRNA genes occupy distinct but changeable nuclear territories according to their epigenetic state.     

亚硝酸盐暴露致雄性小鼠生殖毒性的探讨

目的 探讨亚硝酸盐暴露对雄性小鼠生殖毒性的分子机制。 方法 36只2月龄健康雄性小鼠,随机分为对照组(生理盐水）、低剂量组（60 mg/kg）和高剂量组（120 mg/kg）,每组12只进行亚硝酸盐灌胃3个月,观察小鼠的生长状况,HE染色法观察睾丸组织病理变化,免疫荧光和Western blotting方法分析检测睾丸组织细胞增殖与凋亡情况及DNA甲基化、组蛋白去乙酰化相关酶的表达情况。 结果 亚硝酸盐暴露组小鼠较对照组小鼠体重增加缓慢,睾丸指数降低（P<0.01）,形态发生病理性改变;亚硝酸盐暴露组小鼠睾丸组织细胞增殖较对照组明显减少,细胞凋亡较对照组明显增加（P<0.01）;同时DNA甲基化和组蛋白去乙酰化水平高于对照组（P<0.01）,且均具有剂量依赖性。 结论 亚硝酸盐暴露通过抑制雄性小鼠生长发育及睾丸生精细胞增殖,诱导睾丸生精细胞凋亡,造成雄性生殖毒性;DNA甲基化及组蛋白去乙酰化水平升高,提示表观遗传学可能参与了亚硝酸盐暴露对雄性生殖系统的损伤过程及调控机制。     

MPTP小鼠脑沉默信息调节因子1和缺氧诱导因子-1α的表达及行为学检测

目的本研究旨在研究MPTP模型小鼠中沉默信息调节因子1(SIRT1)和缺氧诱导因子1α(HIF-1α)的表达情况以及行为学的变化。方法选用MPTP处理C57BL/6小鼠构建PD动物模型,采用行为学实验、高效液相色谱(HPLC)、免疫组化等方法检验模型的建立是否成功,并在小鼠模型中检测SIRT1和HIF-1α的表达情况。结果 MPTP处理的小鼠表现出显著的行为学异常,主要体现在自主活动减少(P0.001)、步距缩短(P0.001),且有显著运动迟缓(P0.001)。HPLC结果发现,模型组小鼠纹状体区域多巴胺(DA)及其代谢产物减少(P0.001)。免疫组化结果提示黑质区域多巴胺能神经元标志物酪氨酸羟化酶(TH)和多巴胺转运体(DAT)的表达明显下调(P0.01)。分子生物学方面,PD模型小鼠的SIRT1表达降低(P0.05),HIF-1α表达增加(P0.05)。结论 PD模型小鼠表现出明显的行为学异常,多巴胺能神经元标志物检测提示成功复制PD动物模型,同时发现模型小鼠的SIRT1/HIF-1α的表达异常,提示该信号通路可能参与了PD的疾病过程。     

Aging defined by a chronologic-replicative protein network in Saccharomyces cerevisiae: An interactome analysis

Aging is a multifactorial condition that results in the loss of an organism's fitness over time. Different theories have been formulated to explain the mechanisms of aging, but a synthesis of these theories has not been possible until now. In addition, the increase in molecular data gathered by proteomics projects utilizing different organisms has permitted a better picture of proteins that function in aging. In this sense, the yeast Saccharomyces cerevisiae is a biological model for aging, and it shows two distinct aging states: a replicative state termed the replicative lifespan (RLS) and a quiescent state known as the chronological lifespan (CLS). Interestingly, both RLS and CLS appear to share common groups of proteins, but a combined model of both aging mechanisms has not been defined. Thus, by applying systems biology tools that allow mining of the yeast proteins associated with aging, it was possible to obtain an interactome network in which both RLS and CLS are represented. In addition, four subgraphs comprising ubiquitin-dependent proteasome/regulation of cell growth, nucleic acid metabolism, carbohydrate metabolism/RNA metabolism, and carbohydrate-organic acid-amino acid/DNA metabolism were found within the interactome, defining a new model of aging for yeast termed the chronologic-replicative protein network (CRPN).     

Chromatin condensation in terminally differentiating mouse erythroblasts does not involve special architectural proteins but depends on histone deacetylation

Terminal erythroid differentiation in vertebrates is characterized by progressive heterochromatin formation and chromatin condensation and, in mammals, culminates in nuclear extrusion. To date, although mechanisms regulating avian erythroid chromatin condensation have been identified, little is known regarding this process during mammalian erythropoiesis. To elucidate the molecular basis for mammalian erythroblast chromatin condensation, we used Friend virus-infected murine spleen erythroblasts that undergo terminal differentiation in vitro. Chromatin isolated from early and late-stage erythroblasts had similar levels of linker and core histones, only a slight difference in nucleosome repeats, and no significant accumulation of known developmentally regulated architectural chromatin proteins. However, histone H3(K9) dimethylation markedly increased while histone H4(K12) acetylation dramatically decreased and became segregated from the histone methylation as chromatin condensed. One histone deacetylase, HDAC5, was significantly upregulated during the terminal stages of Friend virus-infected erythroblast differentiation. Treatment with histone deacetylase inhibitor, trichostatin A, blocked both chromatin condensation and nuclear extrusion. Based on our data, we propose a model for a unique mechanism in which extensive histone deacetylation at pericentromeric heterochromatin mediates heterochromatin condensation in vertebrate erythroblasts that would otherwise be mediated by developmentally-regulated architectural proteins in nucleated blood cells. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.