结核分枝杆菌原核泛素蛋白酶体的研究进展

泛素-蛋白酶体系统是细胞内蛋白质降解的重要机制,并参与细胞生理功能调控。研究发现,结核分枝杆菌泛素样蛋白-蛋白酶体系统可调控并介导结核杆菌逃避宿主的免疫监视和杀灭。因此,介于结核分枝杆菌中的类泛素-蛋白酶体系统在结核分枝杆菌的生理功能及其致病过程中的重要性,且被认为是新的结核病药物治疗靶点。此文就真核生物泛素-蛋白酶体系统(Ubiquitin-proteasome system,UPS)与Mtb中的类泛素-蛋白酶体系统(Pup-proteasome system,PPS)的差异展开比较,通过辅助因子Pup,Mpa,Dop,PafA及靶蛋白在Mtb中类泛素-蛋白酶体系统中介导蛋白质降解的过程,进一步阐明辅助因子的缺失和突变对新兴的耐药结核杆菌产生的影响展开作一综述。     

蛋白酶体抑制剂与心肌再灌注损伤

泛素-蛋白酶体系统是真核细胞内蛋白质代谢的重要途径,参与了细胞周期调节、基因转录和表达、脱氧核糖核酸修复、抗原递呈和炎症过程。现就泛素-蛋白酶体系统与心肌再灌注损伤的关系以及抑制蛋白酶体的活性后对心肌再灌注损伤的影响进行综述。     

去泛素化酶在动脉粥样硬化中的研究进展

研究发现泛素-蛋白酶体系统具有重要的泛素化与去泛素化功能,参与许多细胞生物学过程.去泛素化酶是真核细胞中泛素-蛋白酶体系统重要组成部分,可以直接或间接影响炎症、凋亡以及增殖等细胞活动,并调控动脉粥样硬化的进程.鉴于去泛素化酶的重要性,本文综述了去泛素化酶在动脉粥样硬化中的作用及其机制,为临床动脉粥样硬化的诊治提供依据.     

蛋白酶体抑制剂--一种新型抗肿瘤药物

真核细胞增殖、生长及凋亡、生存受到细胞内一系列蛋白质的调控。因此,细胞内蛋白的有序降解对细胞功能、生存极为重要。80%以上的细胞内蛋白质,包括调节细胞周期的多种蛋白的降解均由泛素-蛋白酶体完成。因此,泛素-蛋白酶体通路是细胞内蛋白质降解的主要通路,蛋白酶体自然成为肿瘤治疗中令人关注的靶点[1]。1泛素-蛋白酶体通路泛素-蛋白酶体由两部分组成,即泛素和蛋白酶体。蛋白酶体由20S的核心成分及19S的周边成分构成。核心区成分的主要功能是蛋白裂解,周边成分是调节蛋白。首先由泛素结合目标蛋白质,然后19S调节蛋白识别并结合泛素化…     

泛素-蛋白酶体系统及其与肝病关系的研究现状

泛素-蛋白酶体系统（UPS）主要由泛素、泛素活化酶、泛素结合酶、泛素连接酶、26S蛋白酶体及去泛素化酶等组成,是降解细胞内蛋白质的非溶酶体途径。UPS与多种疾病的发生发展有关,在肝病研究中也具有重要的病理生理意义。本文就UPS及其与肝病关系的研究现状作一综述。     

蛋白酶体抑制剂MG132诱导人巨噬细胞THP-1凋亡

泛素-蛋白酶体途径是生物体内进行蛋白质选择性降解的重要途径之一，广泛参与细胞周期调控、DNA修复、细胞信号转导、细胞凋亡等多种生理过程。为了研究调控泛素一蛋白酶体途径表达对巨噬细胞THP-1凋亡和细胞内载脂蛋白B的蓄积的影响，本实验采用蛋白酶体抑制剂MG132(5／μmol／L)处理THP-1细胞，流式细胞术检测细胞凋亡率和细胞内载脂蛋白B含量，用半定量逆转录一聚合酶链反应检测细胞内UPP途径相关基因的表达。结果发现：MG132可以诱导THP-1细胞凋亡；实验组细胞内载脂蛋白B蓄积增加；实验组细胞内泛素活化酶、泛素缀合酶和泛素-蛋白连接酶mRNA表达均降低，而26S蛋白酶体mRNA无显著改变。结果提示，蛋白酶体抑制荆MG132能够诱导THP-1细胞凋亡，其机制可能与MG132抑制泛素-蛋白酶体途径中泛素活化酶、泛素缀合酶和泛素一蛋白连接酶活性，使细胞内载脂蛋白B经泛素-蛋白酶体途径降解减少，在细胞内蓄积而使细胞凋亡率增加。     

泛素表达和蛋白酶体活性在胃癌及癌旁组织中的研究

目的研究26S蛋白酶体水解活性及泛素在胃癌、癌旁组织与正常胃黏膜组织中的差异。方法对75例胃癌患者分别在胃癌、癌旁及远端正常黏膜组织取样进行研究。采用免疫印迹方法分析泛素表达,免疫荧光方法分析26S蛋白酶体活性。结果泛素表达及26S蛋白酶体活性在胃癌及癌旁组织中增强,均高于正常胃黏膜组织。胃癌中泛素水平(4.24vs3.27)及26S蛋白酶体活性(628.3vs431.8)均高于癌旁组织,差异有统计学意义。结论胃癌中泛素-蛋白酶体系统被异常活化,与胃癌的发生与进展有关。     

泛素连接酶与结缔组织病的关系

蛋白质的泛素化是泛素-蛋白酶体系统降解细胞内蛋白质的主要步骤,通过由泛素激活酶(ubiquitin-activating enzyme,E1)、泛素结合酶(ubiquitin conjugating enzyme,E2)和泛素连接酶(ubiquitin ligase,E3)等一系列酶活动将泛素连接到特定蛋白质分子上,然后连接泛素的蛋白质被蛋白酶体降解或发生功能改变。泛素连接酶(E3)在这个系统中起重要作用,它能够结合特异性底物和E2-泛素复合物,并将底物由E2转移到泛素上。泛素连接酶功能的异常可以引起异常免疫反应,从而导致结缔组织病。本综述将讨论SSA/Ro52、roquin和synoviolin等泛素连接酶与干燥综合征、类风湿关节炎和系统性红斑狼疮等结缔组织病的关系,以明确泛素连接酶在结缔组织病发病机制中的作用。     

类泛素-蛋白酶体系统和药物外排泵抑制剂对结核分枝杆菌单纯利福平耐药性影响的研究

目的探讨类泛素-蛋白酶体系统对结核分枝杆菌单纯利福平耐药性的影响。方法采用刃天青显色法检测利福平对结核分枝杆菌的最低抑菌浓度(minimum inhibitory concentration,MIC),比较分析结核分枝杆菌Pup、Dop、PafA、Mpa基因的过表达或缺失突变对结核分枝杆菌利福平MIC的差异;检测分别加入羰基氰氯苯腙、利血平、维拉帕米和氯丙嗪4种外排泵抑制剂前后各菌株对利福平MIC的影响。结果结核分枝杆菌Pup、Dop、PafA和Mpa基因的过表达均能增强单纯耐利福平结核分枝杆菌对利福平的耐药性,而Pup、Mpa、Dop和PafA基因的缺失均能显著降低单纯耐利福平结核分枝杆菌对利福平的耐药性,P值均0.05。4种药物外排泵抑制剂能不同程度的降低各过表达菌株对利福平的MIC,P值均0.05,并且,类泛素-蛋白酶体系统与外排泵抑制剂之间存在一定交互作用。结论类泛素-蛋白酶体系统对结核分枝杆菌单纯利福平耐药性的产生有影响;类泛素-蛋白酶体系统可能通过调控外排相关通路蛋白来影响结核分枝杆菌单纯利福平耐药性的产生。     

泛素-蛋白酶体系统与呼吸系统疾病

蛋白是细胞功能的主要执行者,蛋白的质量和数量与细胞功能和疾病有着密切的联系。蛋白的降解系统控制着蛋白的数量,泛素一蛋白酶体系统是细胞内蛋白的主要降解系统,负责细胞内大部分蛋白的降解。对于泛素一蛋白酶体与心血管、肿瘤和神经系统的关系目前研究的比较多,一些新的I艋床药物也应运到临床为患者带来福音。而该系统与呼吸系统疾病关系的研究并不多,了解泛素一蛋白酶体系统在呼吸系统疾病中的作用对于呼吸系统疾病的防治有重要的意义。     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

Serological survey of HIV and syphilis in pregnant women in Madagascar

Objectives Peripartal transmission of human immunodeficiency virus (HIV) and Treponema pallidum, the causative agent of syphilis, leads to severe consequences for newborns. Preventive measures require awareness of the maternal infection. Although HIV and syphilis testing in Madagascar could be theoretically carried out within the framework of the national pregnancy follow‐up scheme, the required test kits are rarely available at peripheral health centres. In this study, we screened blood samples of pregnant Madagascan women for HIV and syphilis seroprevalence to estimate the demand for systemic screening in pregnancy. Methods Retrospective anonymous serological analysis for HIV and syphilis was performed in plasma samples from 1232 pregnant women that were taken between May and July 2010 in Ambositra, Ifanadiana, Manakara, Mananjary, Moramanga and Tsiroanomandidy (Madagascar) during pregnancy follow‐up. Screening was based on Treponema pallidum haemagglutination tests for syphilis and rapid tests for HIV, with confirmation of positive screening results on line assays. Results Out of 1232 pregnant women, none were seropositive for HIV and 37 (3%) were seropositive for Treponema pallidum. Conclusions Our findings are in line with previous studies that describe considerable syphilis prevalence in the rural Madagascan population. The results suggest a need for screening to prevent peripartal Treponema pallidum transmission, while HIV is still rare. If they are known, Treponema pallidum infections can be easily, safely and inexpensively treated even in pregnancy to reduce the risk of transmission.     

Variabilité des concentrations plasmatiques de l’angiotensinogène et risque d’hypertension artérielle chez le rat transgénique

Aim

Genetic polymorphisms of the human angiotensinogen gene are frequent and may induce up to 30% increase of plasma angiotensinogen concentrations with a blood pressure increase of up to 5 mmHg. Their role for the pathogenesis of human arterial hypertension remains unclear. High plasma angiotensinogen levels could increase the sensitivity to other blood pressure stressors.

Methods

Male transgenic rats with a 9-fold increase of plasma angiotensinogen concentrations and male non-transgenic rats aged 10 weeks were treated or not with NG-Nitro-L-arginine-methyl ester for 3 weeks in their drinking water (n = 3/group). Systolic blood pressure and body weight were measured at baseline and at the end of the study when left ventricular weight and ventricular expression of angiotensin I-converting enzyme and procollagen Iα1 were determined (polymerase chain reaction).

Results

At baseline, transgenic rats had +18 mmHg higher bood pressure and –8% lower body weight compared to non-transgenic rats (P < 0.05) without significant changes for the vehicle groups throughout the study (P > 0.05). NG-Nitro-L-arginine-methyl ester increased blood pressure, left ventricular weight and left ventricular weight indexed for body weight by +41%, +17.6% and +18.6% (P < 0.05) in transgenic and +25%, +5.3% and +6.7% (P > 0.05) in non-transgenic rats compared to untreated animals, respectively. Cardiac gene expression showed no differences between groups (P > 0.05).

Conclusion

Increased plasma angiotensinogen levels may sensitize to additional blood pressure stressors. Our preliminary results point towards an independent role of angiotensinogen in the pathogenesis of human hypertension and associated end-organ damage.     

Morphological and immunocytochemical heterogeneity of cultured pinealocytes from one-week-and two-month-old rats: Planimetric and densitometric investigations

Abstract: In vitro preparations of rat pinealocytes are widely used for biochemical analyses of signal transduction processes. This paper deals with morphological and immunocytochemical features of such preparations. Special attention was paid to the problems of whether pinealocytes represent a heterogeneous cell population and how such heterogeneity may develop during ontogeny. The investigations were performed with cells which were obtained from the pineal organ of one-week-and two-month-old rats, attached to synthetic peptide-coated coverslips or tissue culture chamber slides, and maintained under in vitro conditions overnight. The attached cells were then fixed with paraformaldehyde. These preparations yielded monolayers of spherical cells of different sizes; most cells were isolated, but some of them were aggregated and formed small clusters. On the average, the cells from the one-week-old animals were smaller than the cells from the two-month-old animals. Immunocytochemical demonstration of S-antigen, a pinealocyte-specific marker, showed that the majority of the cells from two-month-old animals were intensely or moderately labelled. Pinealocytes from one-week-old animals were less S-antigen immunoreactive. Only very few cells (less than 1% displayed glial fibrillary acidic protein (GFAP)-immunoreactivity. Planimetric investigations of the cell size and semiquantitative densitometric investigations of the intensity of the S-antigen immunoreaction revealed that (i) pinealocytes kept in vitro form a heterogeneous cell population, and that (ii) this heterogeneity increases during postnatal development from one-week-old to two-month-old animals. Two groups of pinealocytes can be distinguished based on their developmental fate: pinealocytes of one group grow dramatically, but show only a moderate increase in S-antigen immunoreactivity, and pinealocytes of the other group retain their size, but display a distinct increment in S-antigen immunoreacti vitv.     

Effects of pinealectomy and melatonin administration on certain indices of ovarian hyperplasia and/or hypertrophy in rats with both ovaries intact or after unilateral ovariectomy

Abstract: In earlier studies from other laboratories it was shown that melatonin decreased ovarian weight in rats and inhibited compensatory hypertrophy of the remaining ovary after unilateral ovariectomy. This study was designed to examine the influence of melatonin on certain indices of ovarian hyperplasia and/or hypertrophy in adult female rats with both ovaries preserved and with either an intact pineal gland or with the pineal gland removed (pinealectomy, PX) or, finally, in sham-PX animals. Similar studies were conducted on rats after unilateral ovariectomy, referring the examined parameters to the remaining intact ovary. The studies included mitotic activity of granulosa layer cells and corpus luteum cells, ovarian weight, ovarian cross-sectional area, cross-sectional area of the granulosa layer of all the Graafian follicles and the cross-sectional areas of the corpora lutea, visible on the ovarian cross-section. On the basis of results, we conclude that: 1) the effect of PX on the processes of ovarian hyperplasia and hypertrophy may vary; analogously, exogenous melatonin administration may influence ovarian hyperplasia and hypertrophy in different ways; 2) PX and exogenous melatonin may, under certain conditions, exert similar biological effects, even synergistic effects; 3) melatonin inhibits ovarian growth processes, while the effects of PX are variable; 4) the results indicate that in experiments performed on rats, with the use of two control groups, i.e., intact and sham-PX, melatonin effects on these two groups may differ.