介导硫化氢生理/病理学效应的靶分子及其分子开关调节的原子生物学机制

硫化氢(H_2S)作为继一氧化氮和一氧化碳后的第三种气体信号分子,日渐受到人们的关注,检测技术的发展为研究提供了帮助。H_2S在人体各系统中发挥着重要的作用,如心血管系统、神经系统、呼吸系统等,其与高血压、动脉粥样硬化、神经退行性疾病、哮喘等疾病的发生发展有着密切的联系,具有作为疾病治疗药物的潜能。对于H_2S作用于靶分子机制的阐述深化了小分子物质调控大分子功能的研究,提供了对多种疾病进行干预的新手段。     

H_2O_2诱导Neuro-2a细胞死亡机理的研究

细胞内线粒体呼吸链过程中的电子漏和神经细胞代谢的酶类如单胺氧化酶(MAO)等可产生活性氧物质(ROS)如H_2O_2等。ROS对细胞有毒性作用,导致细胞死亡,在许多疾病特别是神经退行性疾病中具有重要作用。我们用H_2o_2诱导N-2a神经母细胞瘤细胞,利用光镜、荧光显微镜、透射电镜观察了诱导的N-2a细胞的死亡,结果表明其死亡形式不同于典型的细胞凋亡,而类似于Ⅱ型神经细胞编程性死亡,死亡细胞染色质呈团块状凝集,细胞核膜仍保持完整。DNA不降解形成ladder,且不需要caspase-3,1的活性,但是H_2O_2诱导的Neuro-2a细胞死亡可以被Bcl-X_L,抑制。我们的结果可以说明,ROS介导的细胞毒性作用是导致Ⅱ型神经细胞编程性死亡的一个原因。     

H_2S参与植物气孔运动调节与逆境响应过程研究进展

H_2S是近年来确认的植物气态信号分子,内源H_2S介导了乙烯和ABA等激素诱导气孔关闭的过程,参与植物对盐、干旱及重金属胁迫等多种非生物逆境的应答过程。H_2S与Ca~(2+)、H_2O_2和NO等信号分子相互作用调节气孔运动;外源H_2S通过调节抗氧化酶活性及其基因表达,促进脯氨酸等渗透调节物质积累,提高植物的抗逆性。就近年来有关植物体内H_2S的来源,其在气孔运动调控和胁迫应答中的作用及机制进行阐述。     

环境无机汞对泥鳅视网膜S100表达影响

用含低浓度Hg2 的水饲养泥鳅(Misgurnus anguillicaudatus),研究Hg2 污染对视网膜中S100免疫反应阳性结构数量及分布的影响。用免疫组织化学ABC法标记S100免疫阳性(S100-IR)细胞,显微镜下观察S100免疫反应阳性细胞并计数。结果显示,处理组S100首先在神经节细胞层(GCL)、神经纤维层(NFL)表达,然后逐渐在其他各层表达。与对照组相比,处理组S100免疫反应阳性细胞数显著增多,且该变化与环境中无机汞处理时间成正相关;阳性细胞胞体明显膨胀,突起稠密粗大,S100阳性反应强。研究提示,Hg2 的神经毒害作用导致泥鳅视网膜中S100-IR细胞数的增多。推测Hg2 污染可能对视网膜有伤害性影响,而神经胶质细胞在视网膜修复过程中起了重要作用。     

肌红蛋白与H2S反应的结构功能学研究

近年来,内源性H_2S作为第3种被发现的新型气体信号分子,其生理学作用逐渐受到研究者的重视.在哺乳动物体内,H_2S与血红素蛋白的结合有两种方式,一种是H_2S直接键合血红素中心Fe形成Fe-H_2S复合物;另一种则是H_2S修饰血红素卟啉环,形成硫代血红素结构.我们选用肌红蛋白(myoglobin,Mb)作为研究对象,通过点突变技术改变了血红素活性中心结构,结合紫外-可见光谱学以及X-射线晶体学,研究了H_2S与不同突变型Mb反应后的光谱和结构变化.结果显示:血红素中心近、远端腔微环境的变化,如腔体极性、氢键数目、氢键位置等因素直接影响蛋白质与H_2S的结合,以及硫代血红素(sulfheme)的形成.这些结果为研究血红素蛋白参与内源性H_2S代谢机理提供了重要的实验数据.     

干旱胁迫下拟南芥中H_2S与ABA信号关系研究

以野生型拟南芥(WT)、硫化氢(H_2S)合成酶缺失型突变体lcd、脱落酸(ABA)合成缺失型突变体aba1实生苗为材料,以0.3 mol·L^-1甘露醇模拟干旱胁迫,研究干旱胁迫对ABA含量、H_2S含量的影响,及其在拟南芥抵抗干旱胁迫中的作用及信号关系。结果显示:干旱胁迫显著提高LCD和ABA1基因相对表达以及H_2S含量,ABA含量;干旱胁迫显著抑制突变体lcd、aba1的种子萌发;干旱胁迫下,外施NaHS促进干旱胁迫下WT、lcd和aba1中內源H_2S的产生及上调LCD、ABA1基因相对表达,而外施ABA提高干旱胁迫下WT、aba1中H_2S含量及LCD、ABA1基因相对表达,但是对lcd中H_2S含量及LCD基因相对表达没有显著影响。研究结果表明,信号分子H_2S和ABA在拟南芥的干旱胁迫响应中发挥一定的作用,且H_2S位于ABA的下游参与调控拟南芥的信号过程。     

兼性厌氧细菌硫化氢的产生机理及其生理功能

硫化氢(H_2S)是继一氧化氮(NO)和一氧化碳(CO)后发现的第3种气态信号分子,但其细菌生理学研究才刚刚起步。本文根据作者对奥内达希瓦氏菌的研究,结合新近文献,就细菌的H_2S产生机理及其生理功能作了较为全面的阐述。细菌的H_2S产生途径主要有2条,一是通过降解半胱氨酸产生,二是通过厌氧呼吸产生。产生的H_2S除可为互生性微生物提供能源、供氢体和无机矿质营养外,还具有抑制竞争性微生物的生长,有效占领生态位的作用。H_2S在氧化应答中也起着重要的作用,一方面可抑制过氧化氢酶活性,增加过氧化氢对细菌的杀灭效果;另一方面可作为信号分子激活细菌的氧化应答,诱导拮抗系统的表达,保护细胞免受氧化损伤。这两种看似"矛盾"的作用与H_2S的处理时间有关:短时间处理以抑制为主,而延长处理时间则以保护为主。细菌H_2S产生机理及生理功能的阐明可为硫元素生物地球化学循环规律的揭示和感染性病原细菌的控制提供有益的参考。     

硫化氢在心血管保护过程中免疫炎症调节研究进展

硫化氢(hydrogen sulfide,H_2S)是一种无色、具有臭鸡蛋气味的气体,过去认为只是一种有毒的气体。近年来大量研究证实H_2S是继一氧化氮(nitric oxide,NO)和一氧化碳(carbon oxide,CO)后第三种内源性气体信号分子,同时,H_2S在心血管系统疾病发生、发展过程中起关键的调控作用,但其机制还不明确,已有报道主要通过抗凋亡、抗氧化、调节内皮一氧化氮合酶活性、促进血管新生等;而本文总结了H_2S在缺血性心脏病、动脉粥样硬化等心血管疾病中免疫炎症调节作用及其机制,从而为H_2S生物学功能以及相关心血管疾病的防治提供新的思路。     

干旱胁迫下H_2S信号增强植物叶片的光合作用

干旱胁迫是影响农作物产量最重要的环境因素之一。硫化氢(H_2S)作为第三种气体信号分子在植物体内具有多样且积极的生理功能。目前已了解,H_2S在响应植物干旱胁迫应答以及增强植物光合作用的过程中发挥重要作用,但关于内源性H_2S对干旱胁迫下植物光合作用的调节机制未见报道。该研究以拟南芥哥伦比亚野生型(wild type Col-0,WT)、H_2S产生酶编码基因DES缺失突变体des以及H_2S产生酶编码基因DES过表达突变体OE-DES为实验材料,研究内源性H_2S对干旱胁迫下拟南芥光合作用的调节机制。研究结果显示,植株在正常生长条件下,内源性H_2S促使叶片净光合速率、蒸腾速率、叶绿素含量显著升高;植株遭受干旱胁迫时,内源性H_2S可以显著上调Rubisco和Rubisco活化酶(Rubisco activase,RCA)的表达水平,保护叶绿体结构的完整性,促使叶片净光合速率显著上升,维持叶片相应的蒸腾速率,并且引起叶片气孔关闭和胞间CO_2浓度显著升高。     

H_2S与Ca~(2+)互作提高黄瓜幼苗耐冷性

硫化氢(hydrogen sulfide,H_2S)是一种新型气体信号分子,钙离子(calcium,Ca~(2+))为重要的第二信使,两者在调控植物生长发育及多种逆境胁迫中分别起着重要作用。然而,H_2S和Ca~(2+)信号在调控植物耐冷性中的作用关系并不十分清楚。本研究针对以上问题以‘津优35号’黄瓜为试材进行研究,结果表明,低温胁迫可诱导H_2S信号的产生,且这种信号可被外源Ca~(2+)增强;低温胁迫可诱导Ca~(2+)信号转导相关基因CaM、CIPK5的mRNA表达,且外源H_2S能够上调低温下CaM、CIPK5的表达量;进一步研究发现,外源H_2S和Ca~(2+)可显著增强植株的抗氧化能力,减少活性氧积累,从而降低低温胁迫对黄瓜幼苗的损伤,且加入Ca~(2+)螯合剂乙二醇二乙醚二胺四乙酸(ethylene glycol tetraacetic acid,EGTA)或钙调素拮抗剂氯丙嗪(chlorpromazine,CPZ)后,H_2S对黄瓜幼苗抗氧化能力的促进效应明显减弱,同样的,H_2S清除剂次牛磺酸(hypotaurine,HT)也会降低Ca~(2+)的作用。以上结果表明H_2S与Ca~(2+)信号间存在着复杂的联系,而且他们可以通过相互作用调控黄瓜幼苗的抗氧化系统,从而增强植株耐冷性。     

硫化氢对抗脑缺血再灌注损伤的机制研究进展

硫化氢（H2S）是一种新型内源性气体信使分子,在许多生理和病理生理过程中,尤其在神经保护中,扮演重要角色,既是神经调节剂, 也是神经保护剂。近年来的研究发现,H2S对于脑缺血再灌注损伤具有积极的防治作用,它可通过抗氧化应激、抗炎及抗细胞凋亡等多个途径, 对脑缺血再灌注损伤起保护作用,具有良好的临床应用前景。简介脑内H2S生成途径,综述H2S在中枢神经系统中的生物学效应及其对脑 缺血再灌注损伤的保护作用与机制研究进展,以期为脑缺血再灌注损伤的临床防治提供新思路。     

Hydrogen sulfide as a vasodilator

Gases such as nitric oxide (NO) and carbon monoxide (CO) play important roles both in normal physiology and in disease. The toxic effects of hydrogen sulphide (H2S) on living organisms have been recognized for nearly 300 years. In recent years, however, interest has been directed towards H2S as the third gaseous mediator, which has been shown to exhibit potent vasodilator activity both in vitro and in vivo most probably by opening vascular smooth muscle K(ATP) channels. Of the two enzymes, cystathionine-gamma-lyase (CSE) and cystathionine-beta-synthetase (CBS), which utilize L-cysteine as substrate to form H2S, CSE is believed to be the key enzyme which forms H2S in the cardiovascular system. Recent studies have shown an important role of the vasodilator action of H2S in health and disease.     

Hydrogen sulfide: clandestine microbial messenger?

Although the toxicity of hydrogen sulfide (H(2)S) has been substantiated for almost 230 years, its pivotal roles in both aerobic and anaerobic organisms have only recently become evident. In low oxygen environments with millimolar concentrations of H(2)S, it functions as an electron donor and as an energy source in some systems. At micromolar levels, intracellular H(2)S in aerobic organisms has a vital role in redox balancing. At even lower concentrations, H(2)S provides essential signals in yeast, in the brain and in smooth and cardiac muscles. Here, other possible coordinating roles within and between microorganisms are suggested, including the possibility that H(2)S functions as a signalling mediator in prokaryotes. It is expected that future research will uncover a host of novel functions, not only in eukaryotes but also in prokaryotic species.     

Distinctive core histone post-translational modification patterns in Arabidopsis thaliana

Post-translational modifications of histones play crucial roles in the genetic and epigenetic regulation of gene expression from chromatin. Studies in mammals and yeast have found conserved modifications at some residues of histones as well as non-conserved modifications at some other sites. Although plants have been excellent systems to study epigenetic regulation, and histone modifications are known to play critical roles, the histone modification sites and patterns in plants are poorly defined. In the present study we have used mass spectrometry in combination with high performance liquid chromatography (HPLC) separation and phospho-peptide enrichment to identify histone modification sites in the reference plant, Arabidopsis thaliana. We found not only modifications at many sites that are conserved in mammalian and yeast cells, but also modifications at many sites that are unique to plants. These unique modifications include H4 K20 acetylation (in contrast to H4 K20 methylation in non-plant systems), H2B K6, K11, K27 and K32 acetylation, S15 phosphorylation and K143 ubiquitination, and H2A K144 acetylation and S129, S141 and S145 phosphorylation, and H2A.X S138 phosphorylation. In addition, we found that lysine 79 of H3 which is highly conserved and modified by methylation and plays important roles in telomeric silencing in non-plant systems, is not modified in Arabidopsis. These results suggest distinctive histone modification patterns in plants and provide an invaluable foundation for future studies on histone modifications in plants.     

硫化氢与糖尿病

硫化氢是继一氧化氮和一氧化碳之后的第三种内源性气体信号分子。近年来,内源性硫化氢的产生及生理意义已经被认识,其代谢异常与多种疾病有关。本文综述了近年报道的硫化氢及其内生酶在糖尿病发病及进展中的变化情况,并重点概述硫化氢效应的细胞机制,包括硫化氢对β细胞胰岛素释放和对脂肪细胞葡萄糖摄取的影响。深入理解硫化氢在糖尿病中的作用将为以硫化氢为靶点的糖尿病治疗和抗糖尿病新药设计提供新的思路。     

Relative contribution of OAT1 and OAT3 transport activities in isolated perfused rabbit renal proximal tubules

The expression of both OAT1 and OAT3 along the isolated rabbit renal proximal tubule (RPT) was determined using RT-PCR. They were found to be very strong in S2 segment and weak in S1 and S3 segments. We further examined the relative transport activity of these transporters in isolated perfused rabbit RPT using [(3)H]para-aminohippurate ([(3)H]PAH), and estrone sulfate ([(3)H]ES) as specific substrates for rbOAT1 and rbOAT3, respectively. The transport activity of OAT1 was in the order S2>S1=S3 segments and that of OAT3 was in the order S1=S2>S3 segments. The addition of alpha-ketoglutarate (100 muM) in the bathing medium increased both OAT1 and OAT3 transport activities in all segments of proximal tubule. The kinetics of [(3)H]succinic acid transport, used to measure the activity of sodium dicarboxylate transporter 3 (NaDC3), were examined. The J(max) for succinic acid was in the order S2>S3 and unmeasurable in the S1 segment. Our data indicate that both OAT1 and OAT3 play quantitatively significant roles in the renal transport of organic anions along the proximal tubule but predominately in S2 segment. The relative contribution of both transporters depends on their relative expression levels and may possibly be affected by the activity of NaDC3 in RPT.     

Cellular mechanism underlying the facilitation of contractile response of vas deferens smooth muscle by sodium orthovanadate

Hydrogen sulfide (H(2)S) has been shown to exert cardioprotective effects. However, the roles of extracellular signal-regulated protein kinases 1/2 (ERK1/2) in H(2)S-induced cardioprotection have not been completely elucidated. In this study, cobalt chloride (CoCl(2)), a chemical hypoxia mimetic agent, was applied to treat H9c2 cells to establish a chemical hypoxia-induced cardiomyocyte injury model. The results showed that pretreatment with NaHS (a donor of H(2)S) before exposure to CoCl(2) attenuated the decreased cell viability, the increased apoptosis rate, the loss of mitochondrial membrane potential (ΔΨm), and the intracellular accumulation of reactive oxygen species (ROS) in H9c2 cells. Exposure of H9c2 cells to CoCl(2) or hydrogen peroxide (H(2)O(2)) upregulated expression of phosphorylated (p) ERK1/2, which was reduced by pretreatment with NaHS or N-acetyl-L-cysteine, a ROS scavenger. More importantly, U0126, a selective inhibitor of ERK1/2, mimicked the above cytoprotection of H(2)S against CoCl(2)-induced injury in H9c2 cells. In conclusion, these results indicate that H(2)S protects H9c2 cells against chemical hypoxia-induced injury partially by inhibiting ROS-mediated activation of ERK1/2.     

硫化氢与细胞的增殖和凋亡

硫化氢是内源性气体分子家族中的一员,是一种气体递质（gasotransmitter）。近年来,内源性硫化氢的产生及生理意义已经被认识,其代谢异常与许多疾病有关。本文综述了最近发现的硫化氢对细胞增殖和凋亡的调节作用,并重点概述硫化氢细胞效应的分子机制,包括丝裂原活化蛋白激酶、细胞周期相关激酶、细胞死亡相关基因以及离子通道等的改变。对硫化氢调节细胞生长或死亡的深入了解将为新药设计及许多疾病的治疗提供新的思路。     

Hydrogen sulfide protects H9c2 cells against doxorubicin-induced cardiotoxicity through inhibition of endoplasmic reticulum stress

The roles of hydrogen sulfide (H(2)S) and endoplasmic reticulum (ER) stress in doxorubicin (DOX)-induced cardiotoxicity are still unclear. This study aimed to dissect the hypothesis that H(2)S could protect H9c2 cells against DOX-induced cardiotoxicity by inhibiting ER stress. Our results showed that exposure of H9c2 cells to DOX significantly inhibited the expression and activity of cystathionine-γ-lyase (CSE), a synthetase of H(2)S, accompanied by the decreased cell viability and the increased reactive oxygen species (ROS) accumulation. In addition, exposure of cells to H(2)O(2) (an exogenous ROS) mimicked the inhibitory effect of DOX on the expression and activity of CSE. Pretreatment with N-acetyl-L: -cysteine (NAC) (a ROS scavenger) attenuated intracellular ROS accumulation, cytotoxicity, and the inhibition of expression and activity of CSE induced by DOX. Notably, the ER stress-related proteins, including glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) were obviously upregulated in DOX-treated H9c2 cells. Pretreatment with sodium hydrosulfide (NaHS, a H(2)S donor) before DOX exposure markedly suppressed DOX-induced overexpressions of GRP78 and CHOP, cytotoxicity and oxidative stress. In conclusion, we have demonstrated that ROS-mediated inhibition of CSE is involved in DOX-induced cytotoxicity in H9c2 cells, and that exogenous H(2)S can confer protection against DOX-induced cardiotoxicity partly through inhibition of ER stress.