首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 62 毫秒
1.
{{@ convertAbstractHtml(article.abstractinfoCn, "cn")}}    相似文献   

2.
多胺是广泛存在于哺乳类组织细胞中的小分子有机化合物,参与细胞的生长和分化等重要的生理过程,也是肿瘤细胞的快速生长所必需。鸟氨酸脱羧酶(omithine decarboxylase,ODC)是多胺合成代谢途径中的第一个限速酶,ODC活性的异常会引起包括肿瘤在内的一系列疾病的发生,由此该酶成为近年来研究的热点。简要综述了ODC与肿瘤关系的研究进展。  相似文献   

3.
多胺是生物体内广泛存在的一类具有多种生物活性的低分子化合物,其合成的关键限速酶是鸟氨酸脱羧酶,鸟氨酸脱羧酶和多胺共同参与生物生长发育等重要生理过程。细菌鸟氨酸脱羧酶在结构上和真核生物略有不同,但是功能类似,其能通过促进多胺的产生发挥对细菌的调节作用。研究发现,细菌鸟氨酸脱羧酶也参与细菌对其他物种的作用,但对人体的作用尚不明确。因此,本文综述了国内外关于细菌鸟氨酸脱羧酶在促进细菌生长、适应环境、抗生素抗性和生物膜形成等方面的作用及相关机制,希望能对细菌鸟氨酸脱羧酶及其作用的后续研究提供一些信息与参考。  相似文献   

4.
探讨鸟氨酸脱羧酶(ornithine decarboxylase,ODC)反义RNA是否对人淋巴瘤细胞Jurkat的生长具有抑制作用。含反义RNA的真核表达载体pcDNA3.1(+)/Rodc用脂质体转染Jurkat细胞,G418筛选ODC表达抑制的细胞株,MTS法分析细胞增殖,Western blotting检测细胞中ODC蛋白表达水平,半定量RT-PCR检测细胞中ODC mRNA含量,流式细胞术检测细胞周期的变化,DNA片段化分析细胞凋亡。结果显示,成功获得ODC表达抑制的淋巴瘤细胞株J/o,ODC反义RNA转染细胞后,引起Jurkat细胞生长缓慢和S/G2细胞周期停滞,细胞对抗癌药物DFMO敏感性显著增加。由此证明,ODC反义RNA能抑制人T淋巴瘤Jurkat细胞的生长,具有治疗人白血病的潜在应用价值。  相似文献   

5.
以部分肝切除诱导的雄性SD大鼠(180~200 g)早期再生肝为材料,用RT-PCR法分析皮质酮处理后再生肝鸟氨酸脱羧酶及抗酶mRNA水平变化.结果表明,皮质酮对鸟氨酸脱羧酶mRNA水平具有剂量依赖性抑制作用;10、20 mg/kg体重皮质酮对抗酶mRNA水平影响不大,40 mg/kg处理可促进其转录.  相似文献   

6.
鸟氨酸脱羧酶基因反义RNA对前列腺癌细胞生长的抑制作用   总被引:4,自引:0,他引:4  
为研究鸟氨酸脱羧酶 (ODC)基因反义RNA对前列腺癌细胞的生长抑制作用 ,将表达ODC第 3外显子反义RNA的重组腺病毒rAd ODC Ex3as分别感染前列腺癌细胞株PC 3和LNCap .通过MTT法观察其对前列腺癌细胞增殖的影响 ,并确定不同细胞合适的感染滴度 ,再采用Western印迹和流式细胞术检测rAd ODC Ex3as对细胞中ODC表达的抑制作用、对细胞周期和凋亡的影响以及与CDK抑制物p2 1的关系 .实验显示 ,rAd ODC Ex3as分别以 5 0MOI、2 5MOI感染PC 3和LNCap细胞可明显抑制其生长增殖 ,而不引起细胞毒性作用 ;其对两种细胞中ODC表达的抑制作用分别为4 5 %和 5 9% .流式细胞DNA含量分析证实 ,rAd ODC Ex3as可引起PC 3和LNCap细胞周期G1期阻滞 ,但并未引起凋亡 .通过Western印迹发现 ,细胞中ODC表达的降低可诱导p2 1蛋白的过表达 .结果表明 ,rAd ODC Ex3as在体外能有效地干扰ODC基因的表达 ,并通过诱导p2 1的过表达使其细胞周期停于G1期 ,从而抑制前列腺癌细胞PC 3和LNCap的增殖 ,为其进一步基因治疗的研究打下基础 .  相似文献   

7.
Ornithine decarboxylase (ODC) activity increases by 2 times in the process of progesterone-induced Bufo oocyte maturation (Table 1). Tumor promotor phorbol ester (PMA) is unable to affect both basal and stimulated ODC activity (Fig. 5) although it is capable of elevating the rate of steroid-induced maturation (Fig. 4). Spermine can inhibit significantly ODC activity of oocytes (Fig. 3). Hormone-stimulated ODC activity falls by 17% when Bufo oocytes are cultured in the alkaline Ringer's solution containing 5 mM spermine (pH 11.6) (Fig. 2). The period, however, is shortened by more than 50% during which the oocytes undergo GVBD (Fig. 1). Otherwise, spermine is found to repress ODC activity in dose dependent manner when microinjected in Bufo oocytes (Fig. 3). But oocytes undergo GVBD with a frequency of more than 80% when progesterone-induced increment of the enzyme activity is totally inhibited in the oocytes injected with approximately 50 nl 4.0 mM spermine. The conclusion may emerge from the above-stated results that increased ornithine decarboxylase activity is not essential for progesterone-induced Bufo oocyte maturation. In addition, ODC activity begins to increase rapidly when endogenous spermine level has been lowered to the largest extent in the maturation process. Therefore the endogenous spermine probably acts as a physiologically negative regulator of ODC activity since exogenous spermine inhibits seriously ODC activity of Bufo oocytes.  相似文献   

8.
根据鸟氨酸脱羧酶(ODC)催化底物L-鸟氨酸脱羧生成腐胺,从而引起培养基中pH升高的特点,设计了一种高效、经济的筛选方法,并以此作为初筛手段从土壤中快速分离可产生较高ODC活力微生物菌种。研究发现培养后pH的变化与微生物产酶能力存在着明显的正相关性,R2=0.914 2。对从土壤和活性污泥样品中分离得到的343株细菌进行有效初筛以及经过摇瓶发酵测定酶活的复筛试验后,筛选得到6株高酶活的菌株,其中菌株CJW07和CGW27的ODC活性分别达到了121.32 U/mL和109.25 U/mL。  相似文献   

9.
鸟氨酸脱羧酶基因反义RNA对肝癌细胞HepG2的影响   总被引:1,自引:0,他引:1  
目的:探讨鸟氨酸脱羧酶(ornithine decarboxylase,ODC)基因反义RNA对肝癌细胞HepG2的影响。方法:构建ODC反义RNA的真核表达质粒,将此质粒转染HepG2细胞后,RT-PCR和Western印迹法筛选ODC表达抑制的细胞株。以此细胞株为模型,分析ODC反义RNA对细胞生长、细胞周期和对抗癌药物米托蒽醌敏感性的影响。结果:成功构建ODC反义RNA真核表达载体并获得稳定低表达ODC的肝癌细胞株Hr1。与对照细胞相比,ODC低表达引起HepG2细胞生长抑制,72h生长抑制率为31%;流式细胞术检测细胞周期发现,Hr1G1期细胞数(56.2%)显著性高于对照(48.2%),而S期细胞(25.5%)则显著性低于对照(34.9%),提示ODC低表达导致G1期阻滞;用米托蒽醌(100μg/L)处理两种细胞后发现,Hr1对药物的敏感性显著性高于对照细胞,处理48h后药物对HepG2和Hr1的抑制率分别是33.4%和60.6%,72h后的抑制率分别是60.8%和83.8%。结论:ODC反义RNA能抑制肝癌HepG2细胞生长,在抗肿瘤治疗中具有潜在的临应用价值。  相似文献   

10.
克隆人鸟氨酸脱羧酶抗酶1(Homo sapiensornithine decarboxylase antizyme 1,HOAZ1)开放性阅读框+1核糖体移码位点缺失的突变基因,构建突变基因的原核表达质粒,分离纯化其原核表达的重组蛋白。采用巢式-PCR和重叠延伸-PCR技术,从人非小细胞肺癌细胞株A549的cDNA中获得人类鸟氨酸脱羧酶抗酶1开放性阅读框+1核糖体移码(+1RF)位点缺失突变的基因序列(DM-HOAZ1)。将该序列克隆到原核表达载体pET-28a(+)后,转化表达菌Rosseta(DE3)感受态细胞。阳性克隆用IPTG诱导重组蛋白表达,然后在尿素变性条件下经Ni-NTA树脂亲和层析纯化重组HOAZ1。原核表达和纯化的HOAZ1重组蛋白用Western Blot鉴定。结果显示,成功获得HOAZ1开放阅读框中+1RF位点缺失的突变基因和该突变基因的原核表达质粒pET-28a(+)/DM-HOAZ1;用pET-28a(+)/DM-HOAZ1转化大肠杆菌后,HOAZ-1可被IPTG诱导性高表达,且表达量随诱导时间延长递增;原核表达的HOAZ1可用Ni-NTA树脂亲和层析有效纯化。建立了原核表达和分离纯化HOAZ1蛋白的试验方法,为进一步研究HOAZ1的功能和临床应用奠定了基础。  相似文献   

11.
Abstract: Heparin, a highly sulfated glycosaminoglycan, is known to be obligatory for long-term endothelial cell cultures; it potentiates the mitogenic activities of endothelial cell growth factors and prolongs the replicative life span of the cells. Here we have shown that besides its growth factor-supportive role, heparin exerts a specific action on cerebral capillary endothelial cells (cECs), unrelated to serum or growth factors, by increasing activity of ornithine decarboxylase (ODC; EC 4.1.1.17) in these cells. For our experiments we have used two different types of cloned cECs: type I cECs, grown in the presence of endothelial cell growth factor and heparin, and type II cECs, usually cultivated without growth factors. Heparin action on ODC activity was shown to be dose dependent within the range of 1–100 μg/ml. Increasing concentrations of or depletion of endothelial cell growth factor from type I cultures had no effect on ODC activity. The increase in enzyme activity was highest after 30 min to 1 h of heparin treatment. As evidenced by northern analysis, the heparin-mediated enhancement of ODC activity was not accompanied by changes of ODC mRNA levels. Studies of DNA replication revealed that in the absence of heparin-binding growth factors, heparin did not affect the proliferative activity of cloned cECs.  相似文献   

12.
Detection of Ornithine Decarboxylase Antizyme in Mouse Brain   总被引:1,自引:4,他引:1  
Ornithine decarboxylase, the rate-limiting enzyme in polyamine synthesis, is known to be regulated by a macromolecular inhibitor, termed antizyme, in a number of cellular systems. The present results show that the antizyme is also a functional component of polyamine metabolism in the brain. It could be demonstrated both in normal randomly selected mice and in animals which had been subjected either to intracerebroventricular injection of saline, which is known to cause a transient activation of ornithine decarboxylase, or to 1,3-diamino-2-propanol, an antizyme-inducing agent. When compared to tissues or cell systems studied so far, the cytosol fraction from mouse brain homogenate appeared to contain an exceptionally high amount of antizyme, that was bound to some material other than active ornithine decarboxylase. This feature was seen in all the animal groups studied, being most prominent after saline injection, when the amount of dissociable antizyme exceeded 14-fold the corresponding released ornithine decarboxylase activity. In untreated animals the excess was about eightfold and after 1,3-diamino-2-propanol about fivefold.  相似文献   

13.
DL-Allylglycine causes a marked increase in mouse brain ornithine decarboxylase (ODC) activity. The amount of immunoreactive enzyme protein increases concomitantly with the activity, but the enzyme protein decreases more slowly than that of the activity. The amount of immunoreactive ODC in brain is many hundred times that of the catalytically active enzyme. The fact that mouse brain cytosol contains high amounts of dissociable antizyme (an inactivating protein) indicates the existence of an inactive, immunoreactive ODC-antizyme pool. The total antizyme content does not change markedly, but instead there are significant changes in different antizyme pools. Putrescine concentrations start to increase 8 h after treatment with allylglycine and concomitantly with this increase, antizyme is released to inhibit enzyme activity. These results indicate the involvement of antizyme in the inactivation process of ODC.  相似文献   

14.
Changes in the activity of choline kinase were measured in the cerebellum during development. Early transient increase was found in the enzyme activity just prior to and during birth. This period of increase did not coincide with the periods of transient elevation in ornithine decarboxylase and choline acetyltransferase previously observed in the developing cerebellum. The effects of the naturally occurring polyamines (putrescine, spermidine, and spermine) on choline kinase and choline acetyltransferase activities, and of phosphorylcholine (the product of the reaction catalyzed by choline kinase) on ornithine decarboxylase and choline acetyltransferase activities, were also examined. Choline acetyltransferase activity was not influenced by either polyamines or phosphorylcholine. However, choline kinase activity from 7-day-old, but not from adult, cerebellum was increased 25% in the presence of 4 mM spermine. In contrast, low spermidine concentrations (less than 2 mM) inhibited choline kinase activity selectively in 7-day-old cerebellum. Ornithine decarboxylase activity from 7-day-old cerebellum was inhibited in a concentration-dependent manner by phosphorylcholine. The present data together with other previous reports suggest that: (a) polyamines may play a role in choline utilization during development via their regulation of choline kinase activity, on the one hand, and of acetylcholinesterase activity on the other; and (b) during development, a reciprocal regulation of choline kinase and ornithine decarboxylase activities by their respective reaction products may exist, whereby choline kinase activity is regulated in a complex manner by polyamines and, in turn, ornithine decarboxylase is inhibited by phosphorylcholine.  相似文献   

15.
Abstract: Ornithine decarboxylase (ODC), the rate-limiting enzyme in the biosynthesis of polyamines, was measured in the brain and the liver of adrenalectomized rats after an acute S.C. treatment with glucocorticoids. The effects of corticosterone and dexamethasone were compared in three brain areas, the cerebral cortex, hippocampus, and cerebellum. These structures have similar concentrations of cytosolic glucocorticoid receptor, as measured by an in vitro exchange assay using a specific glucocorticoid ligand, [3H]RU 26988, but contain different amounts of mineralocorticoid receptor. Corticosterone and dexamethasone increased ODC activity in the liver and brain areas in a dose dependent manner, dexamethasone being more active than corticosterone in all tissues. Moreover, estradiol, progesterone, and testosterone were inactive. Aldosterone, at high doses, increased brain ODC activity. Glucocorticoids, selected for their weak binding, or lack of binding to the mineralocorticoid receptor, were tested and found to be highly active in inducing brain and liver ODC, thus showing that ODC induction by steroids is specific for glucocorticoids. These results are among the first to suggest biochemically a central action of glucocorticoids following an acute treatment and confirm that the brain is a glucocorticoid target organ.  相似文献   

16.
Ornithine decarboxylase (ODC; EC 4.1.1.17) is a highly inducible, rate-limiting enzyme of the polyamine pathway. We have studied the mechanisms that lead to the induction of ODC activity in response to electrical stimulation in three brain regions. Hippocampal ODC activity was found to exhibit much larger elevations than that of the neocortex and the cerebellum. The levels of ODC gene expression were also followed to examine its relationship to the existing regional differences in ODC activity. In the neocortex, there was an elevation of both the ODC mRNA and enzyme activity. However, the hippocampal ODC mRNA level was not increased by electroconvulsive shock. Furthermore, the effects of hormonal changes and seizures on these regional differences in ODC induction were also examined. Adrenalectomy did not affect ODC activity, but pretreatment with the anticonvulsant MK-801 caused a depression of the induced levels of enzyme activity. Our data suggest that ODC activity in all the brain regions studied is directly elevated by electrically stimulated seizures. However, this induced ODC activity may or may not involve enhanced gene expression.  相似文献   

17.
Mouse brain ornithine decarboxylase activity is about 70-fold higher at the time of birth compared with that of adult mice. Enzyme activity declines rapidly after birth and reaches the adult level by 3 weeks. Immunoreactive enzyme concentration parallels very closely the decrease of enzyme activity during the first postnatal week, remaining constant thereafter. The content of brain antizyme, the macromolecular inhibitor to ornithine decarboxylase, in turn is very low during the first 7 days and starts then to increase and at the age of 3 weeks it is about six times the level of that in newborn mice. This may explain the decrease in enzyme activity during brain maturation, and suggests the regulation of polyamine biosynthesis by an antizyme-mediated mechanism in adult brain.  相似文献   

18.
Abstract: Age-dependent decreases in the levels of ornithine decarboxylase activity were observed in the optic lobes, cerebral hemispheres, and midbrain-diencephalon of 6–17-day-old chick embryos. In dissociated cell cultures from chick embryonic brains a similar pattern of declining ornithine decarboxylase activity with time in culture was observed. Ornithine decarboxylase activity in the dissociated brain cell cultures was stimulated by changing the culture medium. The peak stimulatory effect was shown to occur 12 h after changing the medium. Although serum-free medium stimulated ornithine decarboxylase activity slightly, the presence of serum in the medium was the primary stimulatory factor. Both fetal calf serum and heat-inactivated fetal calf serum produced dose-dependent stimulation of ornithine decarboxylase activity. Dialyzed fetal calf sera stimulated ornithine decarboxylase, but to a lower level than that produced by nondialyzed sera. Insulin (0.5–10 μg/ml) stimulated ornithine decarboxylase activity in a dose-dependent manner in serum free medium. In addition, 102 M-L-asparagine stimulated ornithine decarboxylase activity in serum-free medium.  相似文献   

19.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号