Contribution of plasma membrane Ca^(2+) ATPase to cerebellar synapse function

The cerebellum expresses one of the highest levels of the plasma membrane Ca2+ATPase,isoform 2 in the mammalian brain.This highly efficient plasma membrane calcium transporter protein is enriched within the main output neurons of the cerebellar cortex;i.e. the Purkinje neurons(PNs) .Here we review recent evidence,including electrophysiological and calcium imaging approaches using the plasma membrane calcium ATPase 2(PMCA2) knockout mouse,to show that PMCA2 is critical for the physiological control of calcium at cerebellar synapses and cerebellar dependent behaviour.These studies have also revealed that deletionof PMCA2 throughout cerebellar development in the PMCA2 knockout mouse leads to permanent signalling and morphological alterations in the PN dendrites. Whilst these findings highlight the importance of PMCA2 during cerebellar synapse function and development,they also reveal some limitations in the use of the PMCA2 knockout mouse and the need for additional experimental approaches including cell-specific and reversible manipulation of PMCAs.

Role of platelet plasma membrane Ca^(2+)-ATPase in health and disease

Platelets have essential roles in both health and disease. Normal platelet function is required for hemostasis.Inhibition of platelet function in disease or by pharmacological treatment results in bleeding disorders.On the other hand,hyperactive platelets lead to heart attack and stroke.Calcium is a major second messenger in platelet activation,and elevated intracellular calcium leads to hyperactive platelets.Elevated platelet calcium has been documented in hypertension and diabetes;both conditions increase the likelihood of heart attack and stroke. Thus,proper regulation of calcium metabolism in the platelet is extremely important.Plasma membrane Ca2+-ATPase(PMCA)is a major player in platelet calcium metabolism since it provides the only significant route for calcium efflux.In keeping with the important role of calcium in platelet function,PMCA is a highly regulated transporter.In human platelets,PMCA is activated by Ca2+/calmodulin,by cAMP-dependent phosphorylation and by calpain-dependent removal of the inhibitory peptide.It is inhibited by tyrosine phosphorylation and calpain-dependent proteolysis.In addition,the cellular location of PMCA is regulated by a PDZ-domain-dependent interaction with the cytoskeleton during platelet activation.Rapid regulation by phosphorylation results in changes in the rate of platelet activation,whereas calpain-dependent proteolysis and interaction with the cytoskeleton appears to regulate later events such as clot retraction.In hypertension and diabetes,PMCA expression is upregulated while activity is decreased, presumably due to tyrosine phosphorylation.Clearly,a more complete understanding of PMCA function in human platelets could result in the identification of new ways to control platelet function in disease states.

Plasma membrane Ca^(2+)-ATPases:Targets of oxidative stress in brain aging and neurodegeneration

The plasma membrane Ca2+-ATPase(PMCA)pumps play an important role in the maintenance of precise levels of intracellular Ca2+[Ca2+]i,essential to the functioning of neurons.In this article,we review evidence showing age-related changes of the PMCAs in synaptic plasma membranes(SPMs).PMCA activity and protein levels in SPMs diminish progressively with increasing age. The PMCAs are very sensitive to oxidative stress and undergo functional and structural changes when exposed to oxidants of physiological relevance.The major signatures of oxidative modification in the PMCAs are rapid inactivation,conformational changes,aggregation, internalization from the plasma membrane and proteolytic degradation.PMCA proteolysis appears to be mediated by both calpains and caspases.The predominance of one proteolytic pathway vs the other,the ensuing pattern of PMCA degradation and its consequence on pump activity depends largely on the type of insult,its intensity and duration.Experimental reduction of PMCA expression not only alters the dynamics of cellular Ca2+ handling but also has a myriad of downstream conse-quences on various aspects of cell function,indicating a broad role of these pumps.Age-and oxidation-related down-regulation of the PMCAs may play an important role in compromised neuronal function in the aging brain and its several-fold increased susceptibility to neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease,and stroke.Therapeutic approaches that protect the PMCAs and stabilize[Ca2+]i homeostasis may be capable of slowing and/or preventing neuronal degeneration.The PMCAs are therefore emerging as a new class of drug targets for therapeutic interventions in various chronic degenerative disorders.

Changes in erythrocyte membrane ATPases and plasma lipid peroxides in upper abdominal surgery under intravenous procaine-balanced anesthesia

ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｄｂｌｏｏｄｃｅｌｓａｒｅｒｅｓｐｏｎｓｉｂｌｅｆｏｒｔｈｅｔｒａｎｓｐｏｒｔａｔｉｏｎｏｆｏｘｙｇｅｎａｎｄｃａｒｂｏｎｄｉｏｘｉｄｅｉｎｔｏａｎｄｏｕｔｏｆｔｉｓｕｅｓａｎｄｏｒｇａｎｓｏｆｔｈｅｂｏｄｙ．Ｉｔｓｓｈａ...

Changes of plasma membrane ATPase activity, membrane potential and transmembrane proton gradient in Kandelia candel and Avicennia marina seedlings with various salinities

The salt-secreting mangrove, Avicennia marina, and non-salt-secreting mangrove, Kandelia candel were cultivated in sand with various salinities(0‰, 10‰, 20‰, 30‰, 40‰) for 60 d. Plasma membrane vesicles of high-purity in leaves and roots of A.marina and K. candel seedlings were obtained by two-phase partitioning. The function of the plasma membranes, the activity of ATPase, membrane potential and transmembrane proton gradient, at various salinities were investigated. The results showed that within a certain range of salinity(A. marina and roots of K. candel: 0—30‰; leaves of K.candel: 0—20‰), the activity of ATPase increased with increasing salinity, while high salinity(above 30‰ or 20‰) inhibited ATPase activity. In comparison with A. marina, K. candel appeared to be more sensitive to salinity. The dynamics of membrane potential and transmembrane proton gradient in leaves and roots of A. marina and K. candel seedlings were similar to that of ATPase. When treated directly by NaCl all the indexes were inhibited markedly: there was a little increase within 0—10‰(K. candel) or 0—20‰(A. marina) followed by sharp declining. It indicated that the structure and function of plasma membrane was damaged severely.

The investigation for the relationship among serum leptin, erythrocyte membrane Ca^(2+)-ATPase activity and hypertensive disorder complicating pregnancy

Objective： To study the significance of Leptin and the activity of erythrocyte membrane Ca^2＋-ATPase（EMCA） in the development of hypertensive disorder complicating pregnancy. Methods： Radioimmunoassay was used to test the level of serum Leptin, and the activity of EMCA was determined chemically in 38 pregnant women with hypertensive disorder complicating pregnancy and 36 normotensive pregnant women. Results： The level of serum Leptin in hypertensive disorder complicating pregnancy（gestational hypertension： 13.76 ± 3.46 ng/ml; preeclampsia： 15.76 ± 5.47 ng/ml; eclampsia： 18.32 ± 6.38 ng/ml）was significantly higher than that in normotensive pregnant women （11.33 ± 2.93 ng/ml） ,respectively. The average EMCA activity of patients with hypertensive disorder complicating pregnancy （gestational hypertension： 1.65 ± 0.24 μmol·pi/mg.h ; preeclampsia： 1.37 ± 0.19 μ mol·pi/mg·h;eclampsia：1.12 ± 0.14 μmol·pi/mg·h） was significantly lower than that of normotensive pregnant women（1.83 ± 0.38 μ mol·pi/mg·h）,respectively. There was a negative correlation between the level of serum Leptin and the activity of RMCA in hypertensive disorder complicating pregnancy （r = -0.63）. Conclusion： Inhibition of EMCA activity of erythrocyte in hypertensive disorder complicating pregnancy may increase cytoplasmic free calcium, which contributes to the development of hypertensive disorder complicating pregnancy. The negative correlation between the level of serum Leptin and the activity of EMCA, also suggested that serum Leptin and the activity of EMCA may play a role in the development of hypertensive disorder complicating pregnancy.

Involvement of Plasma Membrane Ca^(2+)/H^+ Antiporter in Cd^(2+) Tolerance

Cation exchangers （CAXs） belong to the cation/Ca2＋exchanger superfamily which have been extensively investigated in plant tonoplasts over the last decade. Recently, the roles of CAXs involved in heavy metal accumulation and tolerance in plants have been studied for phytoremediation and food security. In this mini review, we summarize the roles of the Ca2＋/H＋ antiporter in Ca2＋ signal transduction, maintaining ion homeostasis and sequestering heavy metals into the vacuole. Moreover, we present a possible role of the plasma membrane Ca2＋/H＋ antiporter in heavy metal detoxification.

PMCA1-4及其A端和C端剪接变异体在成年大鼠前庭组织中的表达

目的研究质膜钙ATP酶异构体1-4(plasma membrane Ca^(2+)-ATPase 1-4,PMCA1-4)在成年大鼠前庭组织的分布部位,及其A端和C端剪接变异体的表达类型。方法选择8周龄健康SD大鼠,解剖出内耳器官行前庭切片,同时取前庭椭圆囊斑和球囊斑提取总RNA。通过免疫荧光方法检测PMCA1-4在成年大鼠内耳前庭组织的表达部位,通过逆转录聚合酶链反应(RT-PCR)法检测PMCA1-4的A端和C端剪接变异体在成年大鼠前庭组织的表达类型。结果球囊和椭圆囊荧光染色切片中,于毛细胞和支持细胞的胞体外侧膜可见PMCA1表达,毛细胞纤毛中可见PMCA2强表达,毛细胞和支持细胞的胞体外侧膜可见PMCA3弱表达,PMCA4几乎不表达。4种PMCA亚型在球囊表达的剪接体分别为PMCA1x/b、PMCA2w/b、PMCA3z/(a,b)和PMCA4x/b,它们在椭圆囊的表达类型与球囊相同。结论PMCA1-4在成年大鼠前庭器官的表达部位存在差异,这4种PMCA亚型的剪接体类型也各不相同。这种差异性可能是为了满足前庭组织和亚细胞结构域对Ca2+调节的特殊需求。

大白菜干烧心病发生过程中Ca^(2+)-ATPase活性的变化

人为诱导大白菜干烧心病发生，通过超速离心制备心叶组织细胞膜微囊，测定各细胞器膜的Ｃａ２＋－ＡＴＰａｓｅ活性变化。结果表明，随缺钙天数增加，细胞膜总Ｃａ２＋－ＡＴＰａｓｅ、ＰＭ－Ｃａ２＋－ＡＴＰａｓｅ和ＴＮ－Ｃａ２＋－ＡＴＰａｓｅ活性迅速上升，在处理后第３天达到高峰，随后逐渐下降，而潜在性Ｃａ２＋－ＡＴＰａｓｅ活性却呈逐渐上升趋势。同时，细胞膜透性和丙二醛含量逐渐增大，超氧化物歧化酶（ＳＯＤ）和过氧化物酶（ＰＯＤ）活性则逐渐下降。推测该病的发生与细胞膜钙泵活性变化诱导的钙的第二信使功能有关。

草莓采后微粒体膜Ca^(2+)-ATPase活性与膜脂过氧化水平

测定了常温 (2 5℃ )和低温 (4℃ )贮藏的草莓果实中微粒体膜Ca2 + ATP酶 (Ca2 + ATPase)与超氧化物歧化酶 (SOD)活性、超氧阴离子 (O-·2 )产生速率和丙二醛 (MDA)含量的变化。结果显示 ,随果实衰老 ,低温贮藏的果实微粒体膜Ca2 + ATPase总活性和质膜、线粒体膜及液泡膜上的Ca2 + ATPase活性 ,微粒体膜SOD活性和O-·2 产生速率呈先升高后降低的趋势 ,MDA含量变化与之相反 ;常温贮藏的果实Ca2 + ATPase活性和O-·2 产生速率变化较为迅速 ,与低温类似 ,而SOD活性逐步下降 ,MDA含量不断升高。这些表明 ,草莓果实衰老与细胞质内Ca2 +

外源乙烯对桃果实微粒体膜Ca^(2+)-ATPase活性和膜脂过氧化水平的影响

以'迎庆'桃果实为材料,研究了经外源乙烯(50μL/L)处理12h后,在常温(25℃)下贮藏过程中,果实微粒体膜Ca2+-ATPase活性和膜脂过氧化水平的变化。结果表明:外源乙烯促进果实内源乙烯的生成,刺激膜Ca2+-ATPase活性先上升而后下降,同时加速超氧自由基的产生,提高膜脂过氧化产物丙二醛含量,增强了膜脂过氧化作用;钙调素拮抗剂三氟拉嗪(TFP)和钙通道阻塞剂异博定(VER)均在一定程度上抑制乙烯诱导的上述效应,这表明细胞内Ca2+和CaM参与了外源乙烯反应。

Allosteric inhibitors of plasma membrane Ca^(2+) pumps: Invention and applications of caloxins

Plasma membrane Ca2+pumps(PMCA)play a major role in Ca2+homeostasis and signaling by extruding cellular Ca2+with high affinity.PMCA isoforms are encoded by four genes which are expressed differentially in various cell types in normal and disease states.Therefore, PMCA isoform selective inhibitors would aid in delineating their role in physiology and pathophysiology.We are testing the hypothesis that extracellular domains of PMCA can be used as allosteric targets to obtain a novel class of PMCA-specific inhibitors termed caloxins. This review presents the concepts behind the invention of caloxins and our progress in this area.A section is also devoted to the applications of caloxins in literature. We anticipate that isoform-selective caloxins will aid in understanding PMCA physiology in health and disease. With strategies to develop therapeutics from bioactive peptides,caloxins may become clinically useful in car diovascular diseases,neurological disorders,retinopathy,cancer and contraception.

桃果实采后微粒体膜Ca^(2+)-ATPase活性与膜脂过氧化

以常温(25℃)和低温(4℃)贮藏的迎庆桃果实为试验材料,对其果实硬度、呼吸强度进行了测定,并对微粒体膜Ca2+-ATPase、超氧化物歧化酶(SOD)活性、氧自由基变化和膜的伤害程度进行了研究.结果表明,随桃果实衰老,常温贮藏的果实硬度迅速下降、微粒体膜上的Ca2+-ATPase活性、SOD活性和O2-产生速率均呈跃变式变化,先升高后降低;膜脂过氧化产物MDA的含量逐渐增加;与常温相比,低温可以抑制果实硬度的下降、呼吸速率、Ca2+-ATPase和SOD活性的下降及推迟峰值的出现,同时降低O2?-产生速率和MDA含量.以上结果表明,桃果实衰老与细胞质内Ca2+稳态的破坏和膜脂过氧化作用的加强有密切关系.

糖尿病视网膜病变患者红细胞膜Ca^(2+)-Mg^(2+)-ATPase活性变化及相关研究

目的探讨糖尿病视网膜病变发生发展的有关因素。对40例糖尿病机网膜病变患者红细胞膜Ca^(2+)－Mg^(2+)－ATPasc活性进行了检测，并与红细胞内Ca^(2+)－Ms^(2+)－ATPasc含量、空腹血糖、糖基化血红蛋白及红细胞变形指数等进行了分析。结果糖尿病机网膜病变患者红细胞膜Ca^(2+)－Ms^(2+)－ATPasc活性显著下降（P＜0．01），细胞内Ca^(2+)含量增加（P＜0．01）而Mg^(2+)含量则显著下降（P＜0．01）。糖尿病视网膜病变者红细胞膜Ca^(2+)－Ms^(2+)－ATPasc活性下降与空腹血糖、糖基化血红蛋白、红细胞变形指数及红细胞内Ca^(2+)－Ms^(2+)－ATPasc含量等变化密切相关。结论糖尿病视网膜病变患者红细胞膜Ca^(2+)－Ms^(2+)－ATPasc活性异常下降可能是导致或加速视网膜病变发生发展的原因之一。

渗透胁迫下外源试剂对玉米幼苗微粒体膜Ca^2＋-ATPase活性的影响

以钙离子鳌合剂EGTA、钙通道阻断剂Vp、钙调素拮抗剂TFP和ABA分别处理玉米幼苗,对渗透胁迫下根系和叶片质膜、液泡膜、线粒体膜以及总微膜Ca2+-ATPase活性进行了测定。结果表明,正常条件下,叶片和根系微膜系统总Ca2+-ATPase活性随光照时间延长出现一个峰值。总体比较,渗透胁迫下三种膜上Ca2+-ATPase活性相当,而且均随渗透胁迫发生不同程度的变化。就微膜系统总酶活变化而言,叶片高于根系,渗透胁迫降低叶片酶活;而渗透胁迫对根系酶活性影响不大。分解到三种膜上,渗透胁迫对叶片酶活的提高均表现为正效应,根系上,对线粒体膜和液泡膜酶活提高表现为正效应,而对质膜酶活表现为显著抑制。外源试剂处理发现,ABA和EGTA在叶片上均可逆转PEG降低总酶活的效应,且在处理6 h时使得酶活性显著超过正常水平;而根系上表现不一:其中,Vp对质膜上PEG提高酶活效应抑制作用较大,且显著提高线粒体膜酶活;ABA显著提高液泡膜上酶活性;TFP处理在胁迫前期基本表现为促进作用,而6 h之后大都表现为抑制效应。说明:渗透胁迫下,玉米叶片质膜、液泡膜以及线粒体膜均参与了胞质钙离子稳态的调控过程,外源试剂处理对Ca2+-ATPase具不同程度的调节作用,叶片和根系Ca2+-ATPase对外源试剂响应存在差异性。

卒中型高血压大鼠心肌线粒体Ca^（2＋），Mg^（2＋）—ATPase及膜流动

本文比较了卒中型自发往高血压鼠（ＳＨＲｓｐ）和京都Ｗｉｓｔａｒ正常血压鼠（ＷＫＹ）心肌线粒体Ｃａ￣（２＋），Ｍｇ￣（２＋）－ＡＴＰａｓｅ活力及膜流动性。用定磷法测得ＷＫＹ和ＳＨＲｓｐ的Ｃａ￣（２＋），Ｍｇ￣（２＋）－ＡＴＰａｓｅ活力（２５℃）分别为０．２８７±０．０１６及０．２１８±０．０１７μｍｏｌ／（ｍｉｎ．ｍｇ）（－ｘ±Ｓｘ）。ＳＨＲｓｐ心肌线粒体Ｃａ￣（２＋），Ｍｇ￣（２＋）－ＡＴＰａｓｅ活力降低２４．７％，两组比较有显著差异（Ｐ＜０．０１，ｎ＝９）．以ＤＰＨ标记心肌线粒体膜，测得ＷＫＹ和ＳＨＲｓｐ的荧光偏振值分别为０．１８７±０．００３及０．１８１±０．００３（Ｐ＞０．０５，ｎ＝６）。

问荆碱对大鼠脑囊泡膜Mg^（2＋）－ATPase，Ca^（2＋）－ATPase

问荆碱对大鼠脑囊泡膜Ｍｇ￣（２＋）－ＡＴＰａｓｅ，Ｃａ￣（２＋）－ＡＴＰａｓｅ有显著的抑制作用，对Ｍｇ￣（２＋）－ＡＴＰａｓｅ的抑制机制分别为竞争性抑制（Ｍｇ￣（２＋），Ｋｉ＝４．９３×１０－５ｍｏｌ／Ｌ）、非竞争性抑制（ＡＴＰ，Ｋｉ＝１．０６×１０－４ｍｏｌ／Ｌ），对Ｃａ￣（２＋）－ＡＴＰａｓｅ的抑制机制分别为混合型抑制（Ｃａ￣（２＋），Ｋｉ＝５．０７×１０－５ｍｏｌ／Ｌ）、非竞争性抑制（ＡＴＰ，Ｋｉ＝３．２７×１０－４ｍｏｌ／Ｌ）。

人晶状体上皮细胞系细胞膜Ca^(2+)-ATPase同工异构体2的表达

目的 检测人晶状体上皮细胞系B 3(HLEB 3)中,细胞膜钙ATP酶(PMCA)的同工异构体之一,PMCA2的表达情况。 方法 细胞培养HLEB 3,当细胞培养达 90%融合时,提取其总mRNA,用PMCA2特异性引物,用反向聚合酶链反应(RT PCR)法检测PMCA2在mRNA水平上的表达。提取细胞膜蛋白,经SDS PAGE电泳以及蛋白免疫印记法(Westernblot),用抗 PMCA2的特异抗体检测其在蛋白质水平上的表达。 结果 RT PCR显示PMCA2特异性引物在HLEB 3细胞扩增出唯一 550bp的片段。蛋白免疫印记法证实PMCA2的表达,相对分子质量约为126 000。 结论 HLEB 3细胞中,在mRNA水平以及蛋白质水平均有PMCA2的表达。并有可能在HLEB 3细胞的钙离子平衡调节中发挥重要作用。

若干蝙蝠葛碱衍生物对人红细胞膜Ca^(2+)-Mg^(2+)-ATPase活力的影响

本文测定了数种蝙蝠葛碱衍生物对钙调素(CaM)激活的人红细胞膜Ca^(2+)-Mg^(2+)-ATPase活力的影响。结果表明,这些化合物对该酶都有不同程度的抑制作用,其机制表现为竞争性抑制,过量的CaM能完全逆转这些化合物所引起的抑制。当Ca^(2+)-Mg^(2+)-ATPase被胰蛋白酶(trypsin)限制性酶解完全活化后,其活力不再受CaM激活,但仍被这些化合物所抑制。

质膜Ca^2＋-ATPase的结构与功能

质膜Ca2+-ATPase(PMCA)是P型ATPase家族的一员,在真核细胞中主要负责信号刺激后胞内高浓度Ca2+的清除扫尾工作,并对维持静息状态下较低Ca2+浓度起着重要的调节作用.PMCA的一级结构已被确定,拓扑学结构显示,它有10个跨膜区和3个胞浆功能区.它的4个编码基因可产生4种亚型(PMCA 1~4),这些亚型在功能与分布上存在差异.PMCA的活性可被钙调蛋白等多种因素调节,这与其结构特征息息相关.近年来,PMCA已被证实与脂筏结构有一定关联,它在信号传导和细胞凋亡中的作用也成为目前科学研究的焦点.本文主要对PMCA的结构、亚型和功能的研究现状进行综述.