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高等植物己糖激酶基因研究进展 总被引:1,自引:0,他引:1
己糖激酶(HXK)具有催化己糖磷酸化的作用,是植物体呼吸代谢过程中的关键酶之一。近十几年的研究发现,HXK在植物的糖感知和糖信号转导过程中扮演重要的角色。目前GenBank已登录28种高等植物的HXK同源基因,其在不同物种中均以多基因家族形式存在。HXK基因家族多数成员包括9个外显子,编码492-522个氨基酸。HXK亚细胞定位研究发现,植物HXK家族成员主要分布于线粒体,少数成员存在于细胞质、叶绿体和质体基质中。植物HXK基因家族大部分成员在不同器官或组织中均有表达,但是拟南芥(Arabidopsis thaliana)AtHKL3和水稻(Oryza sativa)OsHXK10仅在花中表达。高等植物部分HXK不仅影响植物生长发育,还调控植物激素信号转导以及调节植物花青素合成途径中相关基因表达。应用MEGA 4.0软件对18个物种HXK基因氨基酸序列构建系统进化树,HXK基因序列聚为7小支,聚类关系能反映不同基因结构和功能的差异。 相似文献
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糖酵解过度活跃是肿瘤细胞能量代谢的显著特征。抑制过度糖酵解已经成为一种新的癌症疗法。重组荞麦胰蛋白酶抑制剂 (recombinant buckwheat trypsin inhibitor, rBTI)可以通过上调磷酸酶及张力蛋白同源基因 (PTEN) 进而抑制HepG2细胞增殖。有关rBTI对肿瘤细胞能量代谢的影响仍未见报道。本研究中的MTT和ATP检测分析表明,rBTI以剂量依赖性方式抑制细胞活力及胞内ATP含量。qRT-PCR和Western印迹分析表明,rBTI处理HepG2细胞后,己糖激酶Ⅱ转录显著下调,但是糖酵解过程中的其他酶及葡萄糖转运蛋白基因在转录水平未发生显著变化,同时己糖激酶Ⅱ蛋白水平的表达也显著下调。酶活性分析也表明,rBTI能显著降低己糖激酶的活性。进一步分析表明, rBTI使细胞内PTEN转录及表达水平明显上调,己糖激酶Ⅱ转录和p-AKT,p-mTOR、己糖激酶Ⅱ的表达下调。当PTEN抑制剂phen存在时,可阻断rBTI诱导的己糖激酶 Ⅱ表达下降,表明rBTI能通过上调PTEN进而影响己糖激酶Ⅱ的表达。免疫荧光及Western印迹分析显示,rBTI作用后减弱了己糖激酶 Ⅱ在线粒体的定位,导致己糖激酶Ⅱ与线粒体电压依赖性阴离子通道蛋白 (voltage-dependent anion channel, VDAC) 分离,促使己糖激酶Ⅱ从线粒体转位到细胞质,降低糖酵解的效率。上述结果证明,rBTI对肿瘤细胞能量代谢的调控作用主要通过抑制PI3K/AKT信号通路,下调己糖激酶Ⅱ的表达并影响空间定位,进而抑制肿瘤细胞糖酵解过程,导致癌细胞生长受到抑制。 相似文献
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目的:探讨大黄素对人胃癌BGC-823细胞凋亡及糖酵解的影响。方法:采用不同浓度大黄素(30μmol/L、90μmol/L、180μmol/L)、磷脂酰肌醇3-激酶(Phosphatidylinositol 3 kinase,PI3K)抑制剂处理人胃癌BGC-823细胞,通过四甲基偶氮唑盐(MTT)检测细胞活力,采用试剂盒检测细胞葡萄糖消耗及乳酸水平,western blotting检测细胞己糖激酶Ⅱ、Bcl-2相关蛋白(Bcl-2 Associated X Protein,Bax)、PI3K、人低氧诱导因子1α(Human Hypoxia-inducible factor 1α,HIF-α)的表达。结果:大黄素能浓度依赖性的抑制BGC-823细胞增殖、葡萄糖消耗,降低乳酸水平;并降低己糖激酶Ⅱ的表达,促进凋亡蛋白Bax表达。PI3K抑制剂可抑制胃癌细胞糖酵解水平,而将大黄素与PI3K抑制剂联合使用后,与单一抑制剂组比,对细胞糖酵解抑制水平进一步加强,大黄素可下调PI3K下游蛋白及HIF-α的表达。结论:大黄素对人胃癌BGC-823细胞的增殖抑制作用其作用机制与调节PI3K途径及HIF-α,并抑制己糖激酶Ⅱ表达降低胃癌细胞糖酵解水平相关。 相似文献
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己糖激酶-Ⅱ与肿瘤的糖代谢 总被引:2,自引:0,他引:2
己糖激酶作为糖酵解途径的第一个关键酶,在肿瘤细胞中有高度表达,并使肿瘤细胞表现出高度的糖分解代谢表型。该介绍己糖激酶一Ⅱ基因的组成特点及其在肿瘤细胞中的表达特征等。 相似文献
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花色形成与花生长的调控 总被引:16,自引:2,他引:16
结合笔者的研究结果,对光、糖和GAs在花生长及花色形成中的作用和可能的调节机制进行了综述。光通过光受体介导的高辐照度反应(HIR)和光合作用调控花生长及花色素苷合成;糖作为碳源和渗透调节因子,影响花瓣细胞的生长及花色素苷积累,依赖己糖激酶的信号途径可能在糖的调控中起作用;GAs通过调节特异基因的转录间接地诱导花色素苷合成途径中结构基因的表达。 相似文献
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转化酶和己糖激酶调控草莓聚合果内糖积累 总被引:4,自引:0,他引:4
以设施栽培的草莓品种‘枥乙女’为试材,用高效液相色谱法分析了果实发育进程中草莓聚合果内不同部位糖含量及相关酶活性的变化。果实成熟过程中草莓聚合果果顶部分含糖量高,中间部位次之,果柄端最低。转化酶活性呈现与糖含量相似的梯度变化。己糖激酶和果糖激酶则表现出与糖梯度相反的变化。上述结果表明,聚合果顶端转化酶活性高,有利于形成蔗糖梯度,从而促进光合产物向果顶端转移;聚合果近果柄端的己糖代谢酶活性高,促进果柄端的己糖消耗,导致果柄端相对低的糖含量。 相似文献
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Rajagopal Balasubramanian Abhijit Karve Brandon d Moore 《Plant signaling & behavior》2008,3(5):322-324
Glucose functions in plants both as a metabolic resource as well as a hormone that regulates expression of many genes. Arabidopsis hexokinase1 (HXK1) is the best understood plant glucose sensor/transducer, yet we are only now appreciating the cellular complexity of its signaling functions. We have recently shown that one of the earliest detectable responses to plant glucose treatments are extensive alterations of cellular F-actin. Interestingly, AtHXK1 is predominantly located on mitochondria, yet also can interact with actin. A normal functioning actin cytoskeleton is required for HXK1 to act as an effector in glucose signaling assays. We have suggested that HXK1 might alter F-actin dynamics and thereby influence the formation and/or stabilization of cytoskeleton-bound polysomes. In this Addendum, we have extended our initial observations on the subcellular targeting of HXK1 and its interaction with F-actin. We then further consider the cellular context in which HXK1 might regulate gene expression.Key words: Arabidopsis, F-actin, glucose signaling, hexokinase, hTalin, mitochondria, polysomes, protoplasts, transient expression assay, fluorescence microscopy 相似文献
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Phosphate (Pi) is one of the least available plant nutrients in soils. It is associated with dynamic changes in carbon fluxes
and several crucial processes that regulate plant growth and development. Pi levels regulate the expression of large number
of genes including those involved in photosynthesis and carbon metabolism. Herein we show that sugar is required for Pi starvation
responses including changes in root architecture and expression of phosphate starvation induced (PSI) genes in Arabidopsis. Active photosynthesis or the supplementation of sugar in the medium was essential for the expression of PSI genes under
Pi limiting conditions. Expression of these genes was not only induced by sucrose but also detected, albeit at reduced levels,
with other metabolizable sugars. Non-metabolizable sugar analogs did not induce the expression of PSI genes. Although sugar
input appears to be downstream of initial Pi sensing, it is absolutely required for the completion of the PSI signaling pathway.
Altered expression of PSI genes in the hexokinase signaling mutant gin2 indicates that hexokinase-dependent signaling is involved in this process. The study provides evidence for requirement of
sugars in PSI signaling and evokes a role for hexokinase in some components of Pi response mechanism. 相似文献
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Smeekens S 《Current opinion in plant biology》1998,1(3):230-234
The molecular details of sugar sensing and sugar-mediated signal transduction pathways are unclear but recent results suggest that hexokinase functions as an important plant sugar sensor in a way that is similar to that found in yeast. The use of mutants in Arabidopsis defective in specific signaling steps is of particular importance because these give access to the genes encoding components in the signaling pathways. In addition, the physiological analysis of such mutants may reveal the interaction of sugar-induced signaling pathways and those induced by other stimuli such as environmental or biotic stress. 相似文献
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A novel type of chloroplast stromal hexokinase is the major glucose-phosphorylating enzyme in the moss Physcomitrella patens 总被引:1,自引:0,他引:1
Hexokinase catalyzes the first step in the metabolism of glucose but has also been proposed to be involved in sugar sensing and signaling both in yeast and in plants. We have cloned a hexokinase gene, PpHXK1, in the moss Physcomitrella patens where gene function can be studied directly by gene targeting. PpHxk1 is a novel type of chloroplast stromal hexokinase that differs from previously studied membrane-bound plant hexokinases. Enzyme assays on a knock-out mutant revealed that PpHxk1 is the major glucose-phosphorylating enzyme in Physcomitrella, accounting for 80% of the total activity in protonemal tissue. The mutant is deficient in the response to glucose, which in wild type moss induces the formation of caulonemal filaments that protrude from the edge of the colony. Growth on glucose in the dark is strongly reduced in the mutant. Sequence data suggest that most plants including Physcomitrella and Arabidopsis have both chloroplast-imported hexokinases similar to PpHxk1 and traditional membrane-bound hexokinases. We propose that the two types of plant hexokinases have distinct physiological roles. 相似文献
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《Trends in plant science》1999,4(3):117-120
The molecular mechanisms by which plant cells sense sugar levels are not understood, but current models (adapted from models for sugar sensing in yeast) favour hexokinase as the primary sugar sensor. However, the hypothesis that yeast hexokinase has a signalling function has not been supported by more recent studies and the idea that hexokinase is involved in sugar sensing in plants has yet to be proven. 相似文献
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A Whittaker A Bochicchio C Vazzana G Lindsey J Farrant 《Journal of experimental botany》2001,52(358):961-969
The phosphorylation of glucose and fructose is an important step in regulating the supply of hexose sugars for biosynthesis and metabolism. Changes in leaf hexokinase (EC 2.7.1.1) activity and in vivo metabolite levels were examined during drying in desiccation-tolerant Sporobolus stapfianus and Xerophyta viscosa. Leaf hexokinase activity was significantly induced from 85% to 29% relative water content (RWC) in S. stapfianus and from 89% to 55% RWC in X. viscosa. The increase in hexokinase corresponded to the region of sucrose accumulation in both species, with the highest activity levels coinciding with region of net glucose and fructose removal. The decline of hexose sugars and accumulation of sucrose in both plant species was not associated with a decline in acid and neutral invertase. The increase in hexokinase activity may be important to ensure that the phosphorylation and incorporation of glucose and fructose into metabolism exceeded production from potential hydrolytic activity. Total cellular glucose-6-phosphate (Glc-6-P) and fructose-6-phosphate (Fru-6-P) levels were held constant throughout dehydration. In contrast to hexokinase, fructokinase activity was unchanged during dehydration. Hexokinase activity was not fully induced in leaves of S. stapfianus dried detached from the plant, suggesting that the increase in hexokinase may be associated with the acquisition of desiccation-tolerance. 相似文献
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Silber Avner Ben-Jaacov Jaacov Ackerman Alexander Bar-Tal Asher Levkovitch Irit Matsevitz-Yosef Tania Swartzberg Dvora Riov Josef Granot David 《Plant and Soil》2002,245(2):249-260
Phosphorus, an essential plant nutrient, may become toxic when accumulated by plants to high concentrations. Certain plant species such as Verticordia plumosa L. suffer from P toxicity at solution concentrations far lower than most other plant species. In this study, exposure of V. plumosa plants to a solution containing as low as 3 mg l–1 P resulted in significant growth inhibition and typical symptoms of P toxicity. In a wide range of P levels studied, micronutrient concentrations in V. plumosa leaves were within the range considered adequate for optimal growth. Notably, tomato plants with high hexokinase activity due to overexpression of Arabidopsis hexokinase (AtHXK1) exhibited senescence symptoms similar to those of P toxic V. plumosa. The resemblance in senescence symptoms between P-toxic tomato plants and those with high hexokinase activity suggested that increased sugar metabolism could play a role in P toxicity in plants. To test this hypothesis, we determined the amount of hexose phosphate, the product of hexokinase, in V. plumosa leaves grown at various P levels in the nutrient solution. Positive correlations were found between concentration in the medium, P concentration in the plant, hexose phosphate concentration in leaves and P toxicity symptoms. Foliar Zn application suppressed P toxicity symptoms and reduced the level of hexose phosphate in leaves. Furthermore, Zn also inhibited hexokinase activity in vitro. Based on these results we suggest that P toxicity involves sugar metabolism via increased activity of hexokinase that accelerates senescence 相似文献
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Master regulators in plant glucose signaling networks 总被引:1,自引:0,他引:1
Jen Sheen 《Journal of Plant Biology》2014,57(2):67-79
The daily life of photosynthetic plants revolves around sugar production, transport, storage and utilization, and the complex sugar metabolic and signaling networks integrate internal regulators and environmental cues to govern and sustain plant growth and survival. Although diverse sugar signals have emerged as pivotal regulators from embryogenesis to senescence, glucose is the most ancient and conserved regulatory signal that controls gene and protein expression, cell-cycle progression, central and secondary metabolism, as well as growth and developmental programs. Glucose signals are perceived and transduced by two principal mechanisms: direct sensing through glucose sensors and indirect sensing via a variety of energy and metabolite sensors. This review focuses on the comparative and functional analyses of three glucose-modulated master regulators in Arabidopsis thaliana, the hexokinase1 (HXK1) glucose sensor, the energy sensor kinases KIN10/KIN11 inactivated by glucose, and the glucoseactivated target of rapamycin (TOR) kinase. These regulators are evolutionarily conserved, but have evolved universal and unique regulatory wiring and functions in plants and animals. They form protein complexes with multiple partners as regulators or effectors to serve distinct functions in different subcellular locales and organs, and play integrative and complementary roles from cellular signaling and metabolism to development in the plant glucose signaling networks. 相似文献