热休克蛋白在脊髓损伤中的研究进展

脊髓损伤(spinal cord injury, SCI)可造成损伤平面以下神经功能障碍,严重影响患者的生活质量。热休克蛋白(heat shock proteins, HSPs)是机体受到应激后保护细胞或组织,使其免受进一步伤害的重要分子之一,在脊髓损伤后表达升高,并通过促进血管生成、抑制炎症反应、抑制神经元凋亡、抗氧化应激等作用减缓脊髓损伤的进一步加重。本文主要就脊髓损伤后热休克蛋白的产生及其作用机制的研究进展进行综述,为后续相关研究提供参考。     

热休克蛋白与自身免疫病相关研究进展

热休克蛋白(heat shock proteins,HSPs)是动物体内一类热应激蛋白,是机体受到高热或其他理化生物等因素刺激时产生的特殊蛋白质。HSPs与自身免疫病的发生发展有着密切关系,在正常生理状态下,HSPs可以在天然免疫反应和适应性免疫反应中分别发挥作用,以帮助机体应对过激环境;而在异常病理条件下,HSPs可参与多种自身免疫病的发生发展。重点概述了HSP22、HSP27、HSP60、HSP70、HSP90与几种常见自身免疫病的相关作用。     

心血管系统热休克蛋白的研究进展

多种应激因素如热应激,缺血,血流动力学变化能引起细胞内代谢异常,细胞骨架紊乱等一系列的病理改变,同时细胞亦相应合成一系列分子量不同的热休克蛋白分子（HSPs)。研究表明,HSPs通过其分子伴侣功能,对细胞产生保护作用。近年来的研究发现,在心肌缺血,缺血预处理,心肌肥大和血管损伤等病理生理条件下,HSP70,HSP90,HSP47,HSP32,HSP27等热休克蛋白分子均参与心血管系统的保护作用。     

极端嗜热古菌的热休克蛋白

随着生物工程产业对于耐高温酶和菌体的需求, 极端嗜热古菌热休克蛋白(heat shock proteins, HSPs)的研究更受重视, 其热休克蛋白体系非常简洁, 不含HSP100s和HSP90s, 就是HSP70(DnaK)、HSP40、(DnaJ)和GrpE等嗜温古菌可能含有的在极端嗜热古菌中几乎不含有, 即仅包括HSP60, sHSP, prefoldin和AAA+蛋白四大类, 因此对其结构、功能和作用机制的研究在理论和实践上都特别有意义。系统地介绍了这四大类组分的结构、功能和作用机制和协同作用的研究进展, 论述了极端嗜热古菌热休克蛋白的系列研究难点和困惑, 展望了进一步的研究方向和重点。     

热休克因子1活性的调控机制

热休克因子1(HSF1)是调控热休克蛋白(HSPs)表达的核心转录因子,可被热应激、氧化应激、缺氧/血、pH下降等刺激因素激活,与靶基因的热休克元件特异性结合,增强HSPs表达,发挥内源性保护作用.HSF1活性的调控发生在HSF1三聚化、转位入核、结合DNA和调节转录等多个环节,受到分子伴侣蛋白、磷酸化作用、氧化-还原等机制共同调控,其复杂而精确的调控对于应激应答、生长发育等过程有重要意义.     

热休克蛋白70在心血管疾病中的保护作用

热休克蛋白(heat shock protein70,HSP70)是HSP家族中重要成员,在生物细胞中含量最高,可诱导性最强,具有保护细胞免受刺激损伤,促进受损细胞修复及抗炎、抗凋亡、耐受缺血/缺氧损伤等多种生物学功能。许多研究发现在心肌组织中HSP70表达升高可减轻心肌细胞损伤程度,利于损伤心肌细胞的恢复,在预防和延缓心血管疾病中起到重要作用。因此,热休克蛋白70诱导剂在心血管疾病的防治中具有潜在的临床价值。本文主要对HSP70在心血管疾病中的保护作用进行综述。     

果蝇热激蛋白的研究进展

热休克蛋白(heat shock proteins,HSPs)是生物体受到应激刺激时诱导产生的一组保守性蛋白,普遍存在于各种生物体中。近年来,果蝇Drosophila作为生命科学与人类疾病研究的重要模式生物,其热激蛋白的研究取得了许多新的进展。文章对果蝇热激蛋白的类别、热激蛋白基因的表达调控机制、热激蛋白的分子伴侣功能、调节细胞存亡和影响发育及寿命等相关生物学功能进行综述,并对热激蛋白在神经退行性疾病治疗中的应用前景作展望。     

热休克蛋白的产生,分布及功能

生物体在各种应激条件下,诸如高温、缺氧、机体损伤、接触某些重金属离子和其它化学物质时,都可能引起的一种生理效应,称之为“热休克反应”(heat shock response)。在热休克反应过程中,细胞内正常蛋白质合成关闭,热休克基因(heat shock gene)的转录被激活,并诱导产生一组特殊蛋白质——热休克蛋白(heat shock proteins,HSP)。     

缺血后处理内源性心脏保护的研究进展

再灌注疗法是临床治疗心肌缺血最有效的措施,但会引起再灌注损伤,调动机体内源性保护机制可以减轻再灌注损伤,保护缺血心肌。缺血预处理（ischemic preconditioning,IPC）和后处理（ischemic postconditioning,I-postC）是缺血心脏有效的内源性保护现象,可以减轻缺血再灌注（ischemia／reperfusion,I／R）后心肌坏死与心肌功能障碍,减少恶性心律失常的发生。内源性心脏保护的机制主要是通过诱导触发因子释放,经多条细胞内信号转导途径的介导,作用于多种效应器,影响氧自由基产生、钙超载等I／R损伤的关键环节而发挥心肌细胞保护作用。特别是可以在缺血后实施的I-postC具有良好的临床应用前景。本文以I-postC为重点综述内源性心脏保护作用、机制及其临床应用现状。     

Ischemic preconditioning phosphorylates mitogen-activated kinases and heat shock protein 27 in the diabetic rat heart

Diabetes mellitus blocks protection by ischemic preconditioning (IPC), but the mechanism is not known. We investigated the effect of ischemic preconditioning on mitogen-activated protein kinases (extracellular signal-regulated kinases 1 and 2, c-Jun N-terminal kinases, p38 mitogen-activated kinase) and heat shock protein 27 phosphorylation in diabetic and nondiabetic rat hearts in vivo. Two groups of anaesthetized nondiabetic and diabetic rats underwent a preconditioning protocol (3 cycles of 3 min coronary artery occlusion and 5 min of reperfusion). Two further groups served as untreated controls. Hearts were excised for protein measurements by Western blot. Four additional groups underwent 25 min of coronary occlusion followed by 2 h of reperfusion to induce myocardial infarction. In these animals, infarct size was measured. IPC reduced infarct size in the nondiabetic rats but not in the diabetic animals. In diabetic rats, IPC induced phosphorylation of the mitogen-activated protein kinases and of heat shock protein 27. We conclude that protection by IPC is blocked by diabetes mellitus in the rat heart in vivo without affecting phosphorylation of mitogen-activated protein kinases or heat shock protein 27. Therefore, the blockade mechanism of diabetes mellitus is downstream of mitogen-activated kinases and heat shock protein 27.     

Myocardial ischemic preconditioning in rodents is dependent on poly (ADP-ribose) synthetase

BACKGROUND: Activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS) in response to oxidant-mediated DNA injury has been shown to play an important role in the pathogenesis of reperfusion injury. Here we investigated the role of PARS in myocardial ischemic preconditioning (IPC). MATERIALS AND METHODS: Mice with or without genetic disruption of PARS and rats in the absence or presence of the PARS inhibitor 3-aminobenzamide underwent coronary occlusion and reperfusion with or without IPC. RESULTS: Both poly(ADP-ribose) synthetase (PARS) deficiency and ischemic preconditioning (IPC) induced protection from reperfusion injury, attenuated inflammatory mediator production, and reduced neutrophil infiltration when compared to the response in wild-type mice. Surprisingly, the protective effect of IPC not only disappeared in PARS-/- mice, but the degree of myocardial injury and inflammatory response was similar to the one seen in wild-type animals. Similarly, in the rat model of IPC, 3-aminobenzamide pretreatment blocked the beneficial effect of IPC. Myocardial NAD+ levels were maintained in the PARS-deficient mice during reperfusion, while depleted in the wild-type mice. The protection against reperfusion injury by IPC was also associated with partially preserved myocardial NAD+ levels, indicating that PARS activation is attenuated by IPC. This conclusion was further strengthened by poly(ADP-ribose) immunohistochemical measurements, demonstrating that IPC markedly inhibits PARS activation during reperfusion. CONCLUSIONS: The mode of IPC's action is related, at least in part, to an inhibition of PARS. This process may occur either by self-auto-ribosylation of PARS during IPC, and/or via the release of endogenous purines during IPC that inhibit PARS activation during reperfusion.     

Decreased tetrahydrobiopterin and disrupted association of Hsp90 with eNOS by hyperglycemia impair myocardial ischemic preconditioning

Cardioprotection by ischemic preconditioning (IPC) is impaired during hyperglycemia, but the mechanisms underlying this phenomenon are poorly understood. This study investigated the role of hyperglycemia to adversely modulate tetrahydrobiopterin (BH(4)) and heat shock protein 90 (Hsp90) during cardioprotection by IPC. Rabbits or mice underwent 30 min of coronary occlusion followed by reperfusion with or without IPC in the presence or absence of hyperglycemia. IPC significantly (P < 0.05) decreased myocardial infarct size (46 ± 1 to 19 ± 2% of the area at risk in control and IPC rabbits, respectively) and increased BH(4) concentrations (HPLC; 7.6 ± 0.2 to 10.2 ± 0.3 pmol/mg protein, respectively), Hsp90-endothelial nitric oxide synthase (eNOS) association (coimmunoprecipitation and Western blotting in mice; 4.0 ± 0.3 to 5.4 ± 0.1, respectively), and the ratio of phosphorylated eNOS/total eNOS. These beneficial actions of IPC on infarct size, BH(4), Hsp90/eNOS, and phosphorylated eNOS were eliminated by hyperglycemia. Pretreatment of animals with the Hsp90 inhibitor geldanamycin (0.6 mg/kg) or the BH(4) synthesis inhibitor diamino-6-hydroxypyrimidine (1.0 g/kg) also eliminated cardioprotection produced by IPC. In contrast, the BH(4) precursor sepiapterin (2 mg/kg iv) restored the beneficial effects of IPC on myocardial BH(4) concentrations, eNOS dimerization, and infarct size during hyperglycemia. A-23871 increased Hsp90-eNOS association (0.33 ± 0.06 to 0.59 ± 0.3) and nitric oxide production (184 ± 17%) in human coronary artery endothelial cells cultured in normal (5.5 mM) but not high (20 mM) glucose media. These data indicate that hyperglycemia eliminates protection by IPC via decreases in myocardial BH(4) concentration and disruption of the association of Hsp90 with eNOS. The results suggest that eNOS dysregulation may be a central mechanism of impaired cardioprotection during hyperglycemia.     

Enhanced IPC by activation of pertussis toxin-sensitive and -insensitive G protein-coupled purinoceptors

Extracellular ATP plays an important role in ischemic preconditioning (IPC) through the activation of P(2y) purinoceptors. This study examined whether ATP-stimulated P(2y) purinoceptors are coupled to pertussis toxin (PTX)-insensitive G protein and whether activation of this pathway enhances myocardial protection afforded by IPC. The rat was treated with PTX for 48 h, and the heart was then isolated and buffer perfused. The heart underwent IPC by three cycles of 5-min ischemia and 5-min reperfusion before 25 min of global ischemia. Isovolumic left ventricular function was measured, and functional recovery at 30 min after reperfusion was taken as an end point of myocardial protection. PTX pretreatment partially inhibited functional protection by IPC. Treatment with 100 microM 8-(p-sulfophenyl) theophylline (SPT) during IPC had no further effect on PTX-induced inhibition of functional protection by IPC, whereas suramin (300 microM) or reactive blue (RB) (10 microM) completely abolished myocardial protection in the preconditioned heart pretreated with PTX. Supplementation with adenosine (30 microM), ATP (30 microM), or UTP (50 microM) significantly enhanced IPC-induced functional protection, although preconditioning with these nucleotides without IPC had no protective effect. Adenosine-enhanced IPC was inhibited by pretreatment with PTX and SPT but not by suramin or RB, whereas ATP-enhanced IPC was inhibited by suramin or RB in combination with PTX pretreatment. On the other hand, UTP-enhanced IPC was not affected by PTX pretreatment but was inhibited by suramin or RB. Adenosine supplemented IPC without PTX pretreatment and ATP supplemented IPC with PTX pretreatment were not affected by nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (100 microM). Although the protein kinase C inhibitor Ro318425 (0.3 microM) or tyrosine kinase inhibitor genistein (50 microM) had no significant effect on the functional protection afforded by adenosine-supplemented IPC without PTX pretreatment and ATP-supplemented IPC with PTX pretreatment, the combination of Ro318425 and genistein attenuated functional protection afforded by both the purinoceptor agonist-supplemented IPC. These results suggest the crucial involvement of PTX-sensitive and -insensitive G protein coupled purinoceptors in enhanced IPC by supplementation with adenosine, ATP, and UTP.     

Does the chloroplast small heat shock protein protect photosystem II during heat stress in vitro?

It has been suggested that the function of the chloroplast-localized small heat shock protein (sHsp) is to protect photosystem II (PSII) from heat inactivation. This paper reports that addition of purified sHsp protein to isolated thylakoid membranes gave no protection of PSII and questions that there is any direct effect of the sHsp on PSII. The opinion is forwarded that the primary role for the chloroplast-localized sHsp may not even be protection of PSII.     

Heat stress proteins and myocardial protection: experimental model or potential clinical tool?

Heat stress proteins (hsp) are induced by a variety of stimuli including elevated temperature, ischaemia, hypoxia, pressure overload and some chemicals. They help to maintain the metabolic and structural integrity of the cell, as a protective response to external stresses. They are known to protect the myocardium from the damaging effects of ischaemia and reperfusion. The heat stress response results in accumulation of heat stress proteins. The beneficial effects associated with their expression include improved endothelial and mechanical recovery of the ischaemic heart. In addition, preservation of high energy phosphates and reduction in infarct size. It has also been shown that critical amounts of hsp70 are necessary to ensure protection of the myocardium. However, questions remain regarding the biochemical mechanisms underlying this protective effect. Alterations in the cell metabolism and chaperone function of cells expressing heat shock proteins, are thought to be responsible. Despite the obvious clinical benefits related to the heat stress response in a clinical setting, the application of this phenomena remains limited. Heat, both quantitatively and qualitatively is one of the best inducers of heat stress proteins. However, the effects of heat stress are nonspecific and intracellular damage is a common occurrence. The search for alternative stimuli, particularly within the fields of pharmacotherapy or genetic manipulation may offer more viable options, if the heat stress response is take its place as an established strategy for myocardial protection.     

Both ischemic preconditioning and ghrelin administration protect hippocampus from ischemia/reperfusion and upregulate uncoupling protein-2

Background  

A major endogenous protective mechanism in many organs against ischemia/reperfusion (I/R) injury is ischemic preconditioning (IPC). By moderately uncoupling the mitochondrial respiratory chain and decreasing production of reactive oxygen species (ROS), IPC reduces apoptosis induced by I/R by reducing cytochrome c release from the mitochondria. One element believed to contribute to reduce ROS production is the uncoupling protein UCP2 (and UCP3 in the heart). Although its implication in IPC in the brain has been shown in vitro, no in vivo study of protein has shown its upregulation. Our first goal was to determine in rat hippocampus whether UCP2 protein upregulation was associated with IPC-induced protection and increased ROS production. The second goal was to determine whether the peptide ghrelin, which possesses anti-oxidant and protective properties, alters UCP2 mRNA levels in the same way as IPC during protection.     

KATP channels and myocardial preconditioning: an update

Ischemic or myocardial preconditioning (IPC) is a phenomenon whereby brief periods of ischemia have been shown to protect the myocardium against a more sustained ischemic insult. The result of IPC may be manifest as a marked reduction in infarct size, myocardial stunning, or incidence of cardiac arrhythmias. Whereas many endogenous neurotransmitters, peptides, and hormones have been proposed to play a role in the signal transduction pathways mediating the cardioprotective effect of IPC, nearly universal evidence indicates the involvement of the ATP-sensitive potassium (KATP) channel. Initial evidence suggested that the surface or sarcolemmal KATP (sarcKATP) channel triggered or mediated the cardioprotective effects of IPC; however, more recent findings have suggested a major role for a mitochondrial site or possibly a mitochondrial KATP channel (mitoKATP). This review presents evidence that supports a role for these two channels as a trigger and/or downstream mediator in the phenomenon of IPC or pharmacologically induced PC as well as recent evidence that suggests the involvement of a mitochondrial calcium-activated potassium (mitoKca) channel or the electron transport chain in mediating the beneficial effects of IPC or pharmacologically induced PC.     

Accumulation of specific ceramides in ischemic/reperfused rat heart; effect of ischemic preconditioning.

Ceramide signalling has been implicated in the mechanism of myocardial ischemia/reperfusion injury (IR). This study tested the hypothesis that ceramides containing a specific amino-linked acyl residue mediate the injury, and that ischemic preconditioning (IPC) affords myocardial protection because it prevents increased ceramide accumulation in IR myocardium. Perfused rat hearts were subjected either to the sham perfusion or to 30 min global ischemia, 30 min ischemia/30 min reperfusion (IR) or were preconditioned prior to the standard IR. The ventricles were harvested for biochemical assay that involved transmethylation of ceramide amino-linked acyl residues, and gas liquid chromatography measurement of acyl methyl esters. Fourteen ceramides containing myrystic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, arachidonic, eicosapentaenoic, behenic, docosapentaenoic, docosahexaenoic or nervonic acid were identified in the myocardium of rats. The total basal ceramide concentration in the myocardium was 135 nmol/g tissue, and it was increased by 14.1% and 48.4% in the ischemia and IR group, respectively. However, in fact, IR increased the accumulation of only 7 out of 14 ceramides identified in the heart (i.e., those containing palmitic, stearic, oleic, linoleic, and arachidonic acid), and the relative magnitude of these increases varied between the particular ceramides and was independent from their basal tissue concentration. IPC improved postischemic hemodynamic recovery and partially prevented the reperfusion-induced increases in these 7 ceramides, while the other ceramides were unaffected by IPC. These results support the role of the specific ceramide signalling in the mechanism of myocardial IR injury. We speculate that by preventing tissue accumulation of certain ceramides, IPC attenuates this signalling, that adds to the mechanism of myocardial protection afforded by IPC.