Plasma membrane calcium pumps and their emerging roles in cancer

Alterations in calcium signaling and/or the expression of calcium pumps and channels are an increasingly recognized property of some cancer cells.Alterations in the expression of plasma membrane calcium ATPase(PMCA) isoforms have been reported in a variety of cancer types,including those of breast and colon,with some studies of cancer cell line differentiation identifying specific PMCA isoforms,which may be altered in some cancers.Some studies have also begun to assess levels of PMCA isoforms in clinical tumor samples and to address mechanisms of altered PMCA expression in cancers.Both increases and decreases in PMCA expression have been reported in different cancer types and in many cases these alterations are isoform specific.In this review,we provide an overview of studies investigating the expression of PMCA in cancer and discuss how both the overexpression and reduced expression of a PMCA isoform in a cancer cell could bestow a growth advantage,through augmenting responses to proliferative stimuli or reducing sensitivity to apoptosis.

Emanuel Strehler’s work on calcium pumps and calcium signaling

Cells are equipped with mechanisms to control tightly the influx, efflux and resting level of free calcium (Ca 2+ ). Inappropriate Ca 2+ signaling and abnormal Ca 2+ levels are involved in many clinical disorders including heart disease, Alzheimer's disease and stroke. Ca 2+ also plays a major role in cell growth, differentiation and motility; disturbances in these processes underlie cell transformation and the progression of cancer. Accordingly, research in the Strehler laboratory is focused on a better understanding of the molecular "toolkit" needed to ensure proper Ca 2+ homeostasis in the cell, as well as on the mechanisms of localized Ca 2+ signaling. A longterm focus has been on the plasma membrane calcium pumps (PMCAs), which are linked to multiple disorders including hearing loss, neurodegeneration, and heart disease. Our work over the past 20 years or more has revealed a surprising complexity of PMCA isoforms with different functional characteristics, regulation, and cellular localization. Emerging evidence shows how specific PMCAs contribute not only to setting basal intracellular Ca 2+ levels, but also to local Ca 2+ signaling and vectorial Ca 2+ transport. A second major research arearevolves around the calcium sensor protein calmodulin and an enigmatic calmodulin-like protein (CALML3) that is linked to epithelial differentiation. One of the cellular targets of CALML3 is the unconventional motor protein myosin-10, which raises new questions about the role of CALML3 and myosin-10 in cell adhesion and migration in normal cell differentiation and cancer.

Plasma membrane calcium pump regulation by metabolic stress

The plasma membrane Ca2+-ATPase(PMCA)is an ATPdriven pump that is critical for the maintenance of low resting[Ca2+]i in all eukaryotic cells.Metabolic stress, either due to inhibition of mitochondrial or glycolytic metabolism,has the capacity to cause ATP depletion and thus inhibit PMCA activity.This has potentially fatal consequences,particularly for non-excitable cells in which the PMCA is the major Ca2+efflux pathway.This is because inhibition of the PMCA inevitably leads to cytosolic Ca2+ overload and the consequent cell death.However,the relationship between metabolic stress,ATP depletion and inhibition of the PMCA is not as simple as one would have originally predicted.There is increasing evidence that metabolic stress can lead to the inhibition of PMCA activity independent of ATP or prior to substantial ATP depletion.In particular,there is evidence that the PMCA has its own glycolytic ATP supply that can fuel the PMCA in the face of impaired mitochondrial function.Moreover, membrane phospholipids,mitochondrial membrane potential,caspase/calpain cleavage and oxidative stress have all been implicated in metabolic stress-induced inhibition of the PMCA.The major focus of this review is to challenge the conventional view of ATP-dependent regulation of the PMCA and bring together some of the alternative or additional mechanisms by which metabolic stress impairs PMCA activity resulting in cytosolic Ca2+ overload and cytotoxicity.

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.

Regulation of specific abnormal calcium signals in the hippocampal CA1 and primary cortex M1 alleviates the progression of temporal lobe epilepsy

Temporal lobe epilepsy is a multifactorial neurological dysfunction syndrome that is refractory,resistant to antiepileptic drugs,and has a high recurrence rate.The pathogenesis of temporal lobe epilepsy is complex and is not fully understood.Intracellular calcium dynamics have been implicated in temporal lobe epilepsy.However,the effect of fluctuating calcium activity in CA1 pyramidal neurons on temporal lobe epilepsy is unknown,and no longitudinal studies have investigated calcium activity in pyramidal neurons in the hippocampal CA1 and primary motor cortex M1 of freely moving mice.In this study,we used a multichannel fiber photometry system to continuously record calcium signals in CA1 and M1 during the temporal lobe epilepsy process.We found that calcium signals varied according to the grade of temporal lobe epilepsy episodes.In particular,cortical spreading depression,which has recently been frequently used to represent the continuously and substantially increased calcium signals,was found to correspond to complex and severe behavioral characteristics of temporal lobe epilepsy ranging from gradeⅡto gradeⅤ.However,vigorous calcium oscillations and highly synchronized calcium signals in CA1 and M1 were strongly related to convulsive motor seizures.Chemogenetic inhibition of pyramidal neurons in CA1 significantly attenuated the amplitudes of the calcium signals corresponding to gradeⅠepisodes.In addition,the latency of cortical spreading depression was prolonged,and the above-mentioned abnormal calcium signals in CA1 and M1 were also significantly reduced.Intriguingly,it was possible to rescue the altered intracellular calcium dynamics.Via simultaneous analysis of calcium signals and epileptic behaviors,we found that the progression of temporal lobe epilepsy was alleviated when specific calcium signals were reduced,and that the end-point behaviors of temporal lobe epilepsy were improved.Our results indicate that the calcium dynamic between CA1 and M1 may reflect specific epileptic behaviors corresponding to different grades.Furthermore,the selective regulation of abnormal calcium signals in CA1 pyramidal neurons appears to effectively alleviate temporal lobe epilepsy,thereby providing a potential molecular mechanism for a new temporal lobe epilepsy diagnosis and treatment strategy.

海嘧啶对肿瘤细胞内[Ca^(2+)]_i的影响

研究表明海嘧啶抗癌疗效确切 ,抗癌机制与其诱导肿瘤细胞凋亡有关 .旨在进一步揭示海嘧啶诱导肿瘤细胞凋亡的机制 ,采用激光扫描共聚焦技术观察海嘧啶对肿瘤细胞内 [Ca2 +]i 的影响及 [Ca2 +]i 变化时Ca2 +的来源 ,采用定磷法测定海嘧啶对肿瘤细胞膜钙泵活性的影响 .海嘧啶可显著升高肿瘤细胞内[Ca2 +]i 的浓度 ;[Ca2 +]i 升高时 ,Ca2 +同时来源于细胞外钙内流和细胞内钙释放 .海嘧啶可显著降低肿瘤细胞膜钙泵活性 .海嘧啶通过升高肿瘤细胞内 [Ca2 +]i 的浓度 ,从而启动肿瘤细胞凋亡机制 ,诱导肿瘤细胞凋亡 ;海嘧啶升高肿瘤细胞内的作用是通过开放肿瘤细胞膜钙通道、引起肿瘤细胞内钙库释放、降低肿瘤细胞钙泵活性三条途径达到的 .

海嘧啶对肿瘤细胞内[Ca^(2+)]_i的影响

目的 揭示海嘧啶诱导肿瘤细胞凋亡的机制。方法 采用激光扫描共聚焦技术观察海嘧啶对肿瘤细胞内[Ca2 +]i 的影响及 [Ca2 +]i 变化时 Ca2 +的来源 ,采用定磷法测定海嘧啶对肿瘤细胞膜钙泵活性的影响。结果 海嘧啶可显著升高肿瘤细胞内 [Ca2 +]i 的浓度 ,[Ca2 +]i 升高时 ,Ca2 +同时来源于细胞外钙内流和细胞内钙释放。海嘧啶可显著降低肿瘤细胞膜钙泵活性。结论 海嘧啶通过升高肿瘤细胞内 [Ca2 +]i 的浓度 ,从而启动肿瘤细胞凋亡机制 ,诱导肿瘤细胞凋亡 ;海嘧啶升高肿瘤细胞内的作用是通过开放肿瘤细胞膜钙通道、引起肿瘤细胞内钙库释放、降低肿瘤细胞钙泵活性 3条途径达到的。

泡沫细胞形成与胞浆Ca^(2+)水平变化

目的 :探讨巨噬细胞在泡沫化过程中 ,胞浆Ca2 +水平的变化规律及其病理机制。方法 :选择动脉粥样硬化易感性C5 7BL/ 6J小鼠 ,取其腹膜巨噬细胞 ,在 10mg·L-1氧化低密度脂蛋白中孵育 96h ,制备了富含脂质成分的泡沫样细胞。在此基础上 ,应用Ca2 +荧光指示剂技术和NADH氧化偶联差光谱变化的分析方法 ,检测了前述泡沫样细胞的胞浆Ca2 +水平及膜成分Ca2 +-ATP酶活性。结果 :泡沫样细胞的胞浆Ca2 +水平是对照巨噬细胞的 2 7倍 ,膜成分Ca2 +-ATP酶活性为后者的 2 4 %。结论 :在巨噬细胞源性泡沫细胞的形成过程中 ,伴随着缓慢的膜外Ca2 +内流或肌质网Ca2 +释放 ,这可能与初期膜上Ca2 +通道的持续性开放及后期膜上Ca2 +泵功能的不可逆性钝化有关。

采用RNA干扰技术分析拟南芥Ca^(2+)泵基因ECAJ的功能

构建了含拟南芥Ca^(2+)泵基因ECA1特异片段反向重复结构的RNA干扰(RNAi)载体,以根癌农杆菌介导转化拟南芥,用卡那霉素筛选和PCR检测,获得了11个T_3代纯合体转基因株系;半定量RT-PCR方法检测ECA1在转基因株系中转录的结果表明,其转录产物比野生型(WT)明显低,且转基因株系之间差异明显,表达水平有一个梯度关系;在1/2MS培养基上转基因株系与野生型的差异不明显,相对于野生型而言,在相对低Ca^(2+)(0.2mmol·L^(-1))或相对高Mn^(2+)(0.5 mmol·L^(-1))的培养基上的转基因株系生长受到不同程度的抑制,ECA1转录量越低,生长受到的抑制越大。据此认为:ECA1对植物的生长发育和抵御逆境胁迫有作用。

拟南芥Ca^(2+)泵基因ACA_2的RNAi载体的构建及转基因植株的筛选

构建了含拟南芥Ca2+泵基因ACA2特异片段反向重复结构的RNA i载体,通过根癌农杆菌介导转化拟南芥,用卡那霉素筛选和PCR检测,获得了12个T3代纯合体转基因株系;半定量RT-PCR方法检测ACA2在转基因株系中转录的结果表明,其转录产物比野生型(WT)明显降低,且转基因株系之间差异明显,表达水平有1个梯度关系,因此,我们初步确定沉默Ca2+泵基因ACA2的RNA i载体是起作用的。

Ca^(2+) cytochemical changes of hepatotoxicity caused by halothane and sevoflurane in enzyme-induced hypoxic rats

AIM： To investigat the relation between hepatotoxicity of halothane and sevoflurane and altered hepatic calcium homeostasis in enzyme-induced hypoxic rats. METHODS： Forty-eight rats were pretreated with phenobarbital and randomly divided into six groups （eight in each group） and exposed to O2/N2/1.2 MAC anesthetics for 1 h： normal control （NC）, 21% O2/79% N2; hypoxic control （HC）, 14% O2/86% N2; normal sevoflurane （NS）, 21% O2/ N2/1.2MAC sevoflurane; hypoxic sevoflurane （HS）, 14% O2/N2/1.2MAC sevoflurane; normal halothane （NH）21%O2/79%N2/1.2MAC halothane; hypoxic halothane （HH）, 14%O2/N2/1.2MAC halothane. Liver specimens and blood were taken 24 h after exposure to calcium and determined by EDX microanalysis. RESULTS： The liver of all rats given halothane （14% O2） had extensive centrilobular necrosis and denaturation. Morphologic damage was accompanied with an increase in serum glutarnic pyruvic transminase. In groups NH and HH, more calcium was precipitated in cytoplasm and mitochondria. CONCLUSION： These results suggest that halothane increases cytosolic Ca^2＋ concentration in hepatocytes. Elevation in Ca^2＋ concentration is implicated in the mechanism of halothane-induced hepatotoxicity. sevoflurane is less effective in affecting hepatic calcium homeostasis than halothane.

Aluminum neurotoxicity effects on intracellular Ca^(2+) homeostasis in the rat cerebral cortex

Studies have suggested that aluminum, a neurotoxic metal, is involved in the progression of neurodegenerative diseases. Previous studies have confirmed that aluminum influences intracellular Ca^2＋ homeostasis. However, it remains unclear whether aluminum increases or decreases intracellular Ca^2＋ concentrations. The present study demonstrated that Al^3＋ competitively binds to calmodulin （CAM）, together with Ca^2＋, which resulted in loss of capacity of CaM to bind to Ca^2＋, leading to increased [Ca^2＋]i. Al^3＋ stimulated voltage-gated calcium channels on cell membranes, which allowed a small quantity of Ca^2＋ into the cells. Al^3＋ also promoted calcium release from organelles by stimulating L-Ca^2＋αlc to trigger calcium-induced calcium release. Although Al^3＋ upregulated expression of Na＋/Ca^2＋exchanger mRNA, increased levels of Ca^2＋ and Na＋/Ca^2＋ exchanger did not maintain a normal Ca^2＋ balance. Al^3＋ resulted in disordered intracellular calcium homeostasis by affecting calcium channels, calcium buffering, and calcium expulsion.

Roles of Na^+/Ca^(2+) exchanger 1 in digestive system physiology and pathophysiology

The Na^+/Ca^(2+) exchanger(NCX) protein family is a part of the cation/Ca^(2+) exchanger superfamily and participates in the regulation of cellular Ca^(2+) homeostasis. NCX1, the most important subtype in the NCX family, is expressed widely in various organs and tissues in mammals and plays an especially important role in the physiological and pathological processes of nerves and the cardiovascular system. In the past few years, the function of NCX1 in the digestive system has received increasing attention; NCX1 not only participates in the healing process of gastric ulcer and gastric mucosal injury but also mediates the development of digestive cancer, acute pancreatitis, and intestinal absorption.This review aims to explore the roles of NCX1 in digestive system physiology and pathophysiology in order to guide clinical treatments.

The effect of external Ca^(2+) and Ca^(2+)-channel modulators on red-light-induced swelling of protoplasts of Phaseolus radiatus L.

Red-light-induced swelling of the protoplasts isolated from hypocotyl of etiolated mung bean (Phaseolus radiatus L.) was observed only when Ca2+ ions were present in the medium. The optimal CaCl2 concentration was 250 μM. Swelling response declined when Ca2+ was supplied into the medium after red light irradiation. The Ca2+-chelator EGTA eliminated the red-light-induced swelling and 45Ca2+ accumulation in the protoplasts. In contrast, A23187, a Ca2+-ionophore, could mimic the effect of red light in darkness. These results indicate that Ca2+ may play a role in light signal transduction. In addition, swelling response was prevented by TFP and CPZ (both are CaM antagonists), implying the involvement of CaM in red-light-induced and Ca2+ -dependent protoplast swelling.

黄精多糖对小鼠心肌组织Ca^(2+)-ATP酶活性的影响

目的研究黄精多糖对小鼠心肌组织Ca泵(Ca2+-ATP酶)活性的影响。方法 72只昆明种小鼠随机分为对照组和黄精多糖低、剂量组、黄精多糖高剂量组,每组24只。经口灌胃4周,将三组小鼠分别于安静时、力竭即刻、力竭恢复24 h三种状态下断头处死,测定心肌组织中Ca2+-ATP酶的活性。结果力竭即刻及力竭恢复24 h,黄精多糖高剂量组Ca2+-ATP酶活性分别为(1.09±0.08)、(0.58±0.07),明显高于对照组和低剂量组(P<0.01)。结论黄精多糖可维持细胞膜内外Ca2+的分布平衡,效果以高剂量黄精多糖最佳。

Relation between Neodymium and Calcium in Rape under Ca-Deficiency

The function of Nd^(3+) with different concentrations in oilseed rape under Ca-deficiency was studied. The results indicate that the root surface-area of rape which treated with 3 μmol·L^(-1) Nd(NO_3)_3 is enlarged, and the taproot length, root dry weight and root CEC all increase as well as roots oxidizing capacity. Nd^(3+) can replace Ca^(2+) partially, and the replacement action is embodied likely through plasmolemma Ca^(2+)-ATPase with signal transduction pathway. Nd^(3+) shows mainly its toxic action under high concentration (60 μmol·L^(-1)).

踝泵训练联合低分子肝素钙治疗脑卒中偏瘫合并下肢深静脉血栓有效性及安全性

目的 探讨踝泵训练联合低分子肝素钙治疗脑卒中偏瘫合并下肢深静脉血栓有效性及安全性。方法 随机选取2020-07—2022-09于武汉大学附属同仁医院/武汉市第三医院诊治的119例脑卒中偏瘫合并下肢深静脉血栓患者为研究对象,按照随机数字表法分为训练组40例、药物组40例及联合组39例,分别给予踝泵训练干预、低分子肝素钙干预及联合干预。分析患者治疗有效性及安全性。观察血液相关指标、肢体功能、日常生活能力变化。结果 联合组治疗有效率(92.31%)明显高于训练组(75.00%)及药物组(70.00%,P<0.05)。干预后,3组患者血液相关指标均明显降低(P<0.05),且联合组纤维蛋白原(FIB)、D-二聚体(D-D)、血浆黏度及全血黏度低于训练组与药物组(P<0.05),凝血酶原时间(PT)水平高于训练组与药物组(P<0.05)。干预后3组患者患者肢体功能均明显升高(P<0.05),联合组各指标高于训练组与药物组(P<0.05)。干预后3组患者患者ADL评分及BI评分均明显升高(P<0.05),联合组各指标高于训练组与药物组(P<0.05)。联合组不良反应发生率(2.56%)明显低于训练组(22.50%)及药物组(22.50%,P<0.05)。训练组与药物组各指标均无统计学差异(P>0.05)。结论 踝泵训练联合低分子钙素钙在脑卒中偏瘫合并下肢深静脉血栓患者的治疗中具有较高的有效性,能够显著减轻血液粘稠度,改善凝血功能与肢体运动功能,有利于提高患者的生活质量,且安全性较高。

低分子肝素钙用于高危产妇剖宫产术后静脉血栓形成预防中对APTT及TT水平的影响

目的探究低分子肝素用于高危产妇剖宫产术后静脉血栓形成预防中对凝血活酶时间(APTT)及凝血酶时间(TT)水平的影响。方法选取洛阳市妇幼保健院2021年1月至2023年1月接受剖宫产手术治疗高危产妇146例作为本次研究对象,按照随机数表法分为两组各73例,对照组接受下肢气压泵治疗,观察组接受下肢气压泵联合低分子钙素钙治疗,对比两组治疗前后凝血功能、血小板指标、下肢肿胀及出血风险性。结果两组术前凝血功能、血小板对比差异无统计学意义(P>0.05),观察组术后APTT、凝血酶原时间(PT)、TT高于对照组,纤维蛋白原(FIB)、血小板(PLT)低于对照组,差异有统计学意义(P<0.05);观察组Ⅰ级、Ⅱ级下肢肿胀发生率低于对照组,差异有统计学意义(P<0.05);两组发生出血的患者均为1例,出血的风险对比差异无统计学意义(P>0.05)。结论高危产妇经剖宫产术后预防性应用低分子肝素钙治疗效果良好,能有效调节凝血功能指标,预防术后静脉血栓形成,且不会增加出血风险,安全性较高。

电针内关穴对心肌缺血再灌注损伤大鼠心肌钙泵活性及其基因表达的影响

目的:研究电针内关穴对缺血再灌注损伤心肌钙泵活性及其基因表达的影响,并以神门穴、合谷穴作对比研究。方法:采用冠脉结扎法建立心肌缺血再灌注模型,无机磷比色法测定钙泵活性、用RT-PCR法分析钙泵的基因表达。结果:缺血再灌注损伤大鼠心肌钙泵基因表达下调,活性降低,电针内关穴在一定程度上上调钙泵的基因表达,增强其活性(P<0.01),电针神门也有促进钙泵基因表达上调,抑制钙泵活性降低的作用,但差于内关组(P<0.01),而电针合谷穴对以上两者均无影响(P>0.05)。结论:电针内关穴可能通过上调心肌钙泵基因表达,增强钙泵活性来减少细胞内钙离子浓度,实现对再灌注损伤心肌组织的保护作用。

电针内关对缺血再灌注损伤大鼠心肌肌浆网钙泵活性及mRNA表达的影响

目的:观察电针内关对缺血再灌注损伤大鼠心肌SERCA活性及其基因表达的影响,并以神门穴、合谷穴作对比研究。方法:实验分为假手术组、心肌缺血再灌注模型组(模型组)、电针内关组、电针神门组、电针合谷组,用无机磷比色法测定SERCA活性、RT-PCR法分析SERCA基因表达。结果:与假手术组比,模型组SERCA活性及其基因表达均有非常显著性差异(P<0.01),电针内关组、电针神门组与模型组比较差异有显著性(P<0.05,P<0.01),电针内关组优于电针神门组(P<0.05,P<0.01)。结论:电针内关上调心肌SERCA基因表达,增强SERCA活性是实现对再灌注损伤心肌组织保护作用的途径之一。电针内关与电针神门两组疗效差异说明经穴对靶器官机制调节作用与经脉(穴)脏腑间的特异联系密不可分。