ABCA1基因调控与动脉粥样硬化的关系

ATP结合盒转运体A1(ABCA1)足一种整合膜蛋白,它以ATP为能源,转运细胞内的游离胆固醇、磷脂至细胞外并与载脂蛋白A1结合,形成高密度脂蛋白.ABCA1基因是胆固醇逆转运和高密度脂蛋白(HDL)生成起始步骤的关键基因.ABCA1的表达在转录和转录后水平受肝X受体/视黄醇X受体(LXR/RXR)等多种因子调控.ABCA1功能障碍将导致动脉粥样硬化的发生、发展,与心脑血管疾病密切相关.     

microRNA对ABCA1调控的研究进展

microRNA(miRNA)对许多生物学过程具有微调作用,ATP结合盒转运体A1(ABCA1)是调节高密度脂蛋白(HDL)代谢和功能的关键蛋白。目前已发现多种miRNA可抑制ABCA1表达,进而抑制胆固醇流出,降低血清HDL水平。而沉默miRNA或抑制其表达则无法抑制胆固醇流出,血清HDL水平无改变。目前对miRNA调控ABCA1表达进行了大量研究,有望带来治疗技术的革新,在调节脂代谢和抗动脉粥样硬化领域具有广阔前景。     

ABCA1促胆固醇流出防治动脉粥样硬化的机制及调控

动脉血管的炎症反应和胆固醇的积累是动脉粥样硬化形成的高危因素,因此抑制巨噬细胞炎症反应和促进胆固醇流出已成为治疗动脉粥样硬化的有效途径。三磷酸腺苷结合盒转运体A1（ATP binding cassette transporter A1,ABCA1）能将细胞内游离胆固醇转运给贫脂的载脂蛋白A-I,从而促进高密度脂蛋白的形成,介导胆固醇的流出。miRNA（microRNA,miRNA） 作为一种非编码的微小RNA,通过降解靶基因mRNA或阻碍其翻译,发挥ABCA1转录后的调控作用。因此探究ABCA1的作用机制及调控有利于动脉粥样硬化的有效防治。     

胆固醇逆向转运关键蛋白介导药物和小分子调控脂代谢的机制研究

胆固醇逆向转运(RCT)异常导致脂代谢紊乱是动脉粥样硬化发病重要环节,探讨介导RCT的关键蛋白在脂代谢中的作用及调控机制对阐明动脉粥样硬化发病的分子机制具有重要意义。本期专题收集的论文探讨了利拉鲁肽、苦瓜素以及生长分化因子11对细胞胆固醇流出及介导RCT中关键蛋白三磷酸腺苷结合盒转运体A1(ABCA1)、ABCG1和B类Ⅰ型清道夫受体表达的影响,分别从不同角度阐释RCT关键蛋白参与药物或小分子物质调控胆固醇流出的分子机制。     

黄芪多糖在动脉粥样硬化发展过程中保护性作用的研究

目的:通过研究黄芪多糖(APS)对肿瘤坏死因子α(TNF-α)诱导的人急性单核白血病细胞(THP-1)源性泡沫细胞胆固醇流出率、细胞内总胆固醇含量以及细胞膜上脂质流出通道ATP-结合盒转运子A1(ABCA1)表达水平的影响,探讨APS在动脉粥样硬化发展过程中的保护作用。方法:将培养的THP-1源性巨噬细胞分为4组:对照组、单纯TNF-α组、TNF-α+APS组和单纯APS组。分别用RT-PCR法、Western blotting法检测ABCA1的mRNA及蛋白表达水平,闪烁计数法计算胆固醇流出率,酶化学法检测细胞内脂质含量,酶联免疫吸附法(ELISA法)测核因子-κB(NF-κB)的水平。结果:单纯TNF-α组ABCA1的mRNA和蛋白表达量、胆固醇流出率显著低于对照组(P<0.01),细胞内总胆固醇含量、NF-κB的水平显著高于对照组(P<0.05),而单纯APS组与对照组在上述指标上差异无统计学意义(P>0.05);与单纯TNF-α组比较,TNF-α+APS组ABCA1的mRNA和蛋白表达量、胆固醇流出率显著升高(P<0.01),细胞内总胆固醇含量、NF-κB的水平显著降低(P<0.01)。结论:APS能够使泡沫细胞ABCA1的表达及胆固醇流出率上升,而细胞内总胆固醇含量显著下降,并能够减弱泡沫细胞中NF-κB的活化水平。这些发现提示APS能够拮抗TNF-α对于ABCA1的下调作用,从而发挥抗动脉粥样硬化作用。     

参与负性调控胆固醇逆向转运的microRNA

加强胆固醇逆向转运(RCT)具有抗动脉粥样硬化作用,microRNA(miRNA)参与多种生物学过程的调控,研究发现多个miRNA参与RCT调控,其通过对RCT的关键蛋白ATP结合盒转运体A1(ABCA1)和受体B类Ⅰ型清道夫受体(SR-BⅠ)的调控而发挥作用。目前已发现多种miRNA可抑制ABCA1和SR-BⅠ蛋白表达水平,进而抑制RCT和胆固醇流出,本文拟就负性调控RCT的miRNA进行综述。     

三磷酸腺苷结合盒转运子A7在脂质转运过程中作用的研究

目的:探讨三磷酸腺苷结合盒转运子A7(ABCA7)在细胞内脂质流出过程中的作用。方法:以apoAI刺激转染ABCA7-或ABCA1-基因的HEK293细胞24h,利用蛋白印迹法以及酶分析法分别测定ABCA7的变化与细胞内胆固醇和磷脂的流出。结果:apoAI分别上调ABCA7或ABCA1蛋白量,ABCA7与ABCA1同样促进细胞内脂质的转运,其中磷脂的流出较胆固醇流出更为明显。结论:ABCA7与ABCA1同样具有促进细胞内脂质转运的功能。     

ATP结合盒转运子A1与动脉粥样硬化(2)

ATP结合盒转运子A1(ABCA1)在血清脂蛋白代谢及细胞胆固醇平衡的维持中起重要作用。贫脂的载脂蛋白A-I是ABCA1介导的磷脂/胆固醇流出的接受体。ABCA1可以通过将胆固醇从肠壁吸收细胞运至肠腔而调节胆固醇的吸收,肠道ABCA1mRNA含量与胆固醇吸收呈负相关。不饱和脂肪酸减少非脂化胆固醇和磷脂的流出,而饱和脂肪酸没有这种作用。动脉硬化饮食15周后,ABCA1转基因鼠主动脉硬化明显减少。     

亲环素A对THP-1源性泡沫细胞ABCA1表达及胆固醇流出的影响及机制

目的观察亲环素A(CypA)对THP-1源性泡沫细胞三磷酸腺苷结合盒转运体A1(ABCA1)表达和胆固醇流出的影响及机制。方法 160 nmol/L佛波酯诱导人THP-1单核细胞分化为巨噬细胞,与50 mg/L氧化型低密度脂蛋白(ox-LDL)共孵育,使其荷脂形成泡沫细胞,常规体外培养细胞;实验分为对照组和Cyp A处理组;液体闪烁计数仪检测细胞胆固醇流出水平,高效液相色谱检测细胞内脂质成分,实时荧光定量PCR和Western blot检测ABCA1表达,Western blot检测核因子κB(NF-κB)核转位水平;NF-κB抑制剂小白菊内酯抑制NF-κB活化;脂质体2000转染CD147 siRNA至THP-1源性泡沫细胞。结果 CypA显著抑制THP-1源性泡沫细胞胆固醇流出,促进NF-κB核转位,下调ABCA1表达;NF-κB抑制剂小白菊内酯拮抗CypA对ABCA1表达及胆固醇流出的抑制作用;用siRNA干扰CD147后,显著抑制Cyp A诱导的NF-κB核转位,上调ABCA1表达,促进胆固醇流出。结论 CypA可能通过CD147激活NF-κB,下调ABCA1表达,抑制THP-1源性泡沫细胞胆固醇流出。     

微小RNA-130a调控人巨噬细胞三磷酸腺苷结合盒转运体A1在动脉粥样硬化的作用

目的探讨微小RNA-130a(microRNA-130a,miR-130a)靶向调控人巨噬细胞三磷酸腺苷结合盒转运体A1(ABCA1)在动脉粥样硬化的作用。方法培养人单核巨噬细胞(THP-1),分为实验组和对照组。利用lipofectamine2000转染试剂,分别将miR-130amimics或阴性对照转染到THP-1中,通过液体闪烁计数测定荷脂THP-1内胆固醇流出情况,高效液相色谱检测细胞内脂质含量;油红O染色显示细胞内脂滴情况。生物信息学软件预测miR-130a的靶基因,并利用双荧光素酶报告基因系统进行验证。通过Western blot检测靶基因ABCA1蛋白表达变化。结果实验组较对照组显著抑制THP-1内胆固醇流出[(5.24±2.36)%vs(12.58±3.92)%,P0.05]。实验组THP-1内胆固醇、胆固醇酯、游离胆固醇较对照组明显增高(P0.05),细胞内脂滴稠密且体积肥大。生物信息学分析显示,miR-130a的靶基因为ABCA1,经体外双荧光素酶报告基因系统检测,证实ABCA1是miR-130a的靶基因。实验组ABCA1蛋白表达水平较对照组明显降低(0.13±0.05 vs 0.38±0.09,P0.05)。结论 miR-130a具有调控THP-1内胆固醇流出的功能,其机制可能与靶向调控ABCA1有关。     

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.     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

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.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.