Elevated extracellular calcium ions accelerate the proliferation and migration of HepG2 cells and decrease cisplatin sensitivity

Hepatoblastoma is the most frequent liver malignancy in children.HepG2 has been discovered as a hepatoblastoma-derived cell line and tends to form clumps in culture.Intriguingly,we observed that the addition of calcium ions reduced cell clumping and disassociated HepG2 cells.The calcium signal is in connection with a series of processes critical in the tumorigenesis.Here,we demonstrated that extracellular calcium ions induced morphological changes and enhanced the epithelial-mesenchymal transition in HepG2 cells.Mechanistically,calcium ions promoted HepG2 proliferation and migration by up-regulating the phosphorylation levels of focal adhesion kinase(FAK),protein kinase B,and p38 mitogen-activated protein kinase.The inhibitor of FAK or Ca2+/calmodulin-dependent kinaseⅡ(CaMKⅡ)reversed the Ca2+-induced effects on HepG2 cells,including cell proliferation and migration,epithelial-mesenchymal transition protein expression levels,and phosphorylation levels of FAK and protein kinase B.Moreover,calcium ions decreased HepG2 cells'sensitivity to cisplatin.Furthermore,we found that the expression levels of FAK and CaMKⅡwere increased in hepatoblastoma.The group with high expression levels of FAK and CaMKⅡexhibited significantly lower ImmunoScore as well as CD8+T and NK cells.The expression of CaMKⅡwas positively correlated with that of PDCD1 and LAG3.Correspondingly,the expression of FAK was negatively correlated with that of TNFSF9,TNFRSF4,and TNFRSF18.Collectively,extracellular calcium accelerates HepG2 cell proliferation and migration via FAK and CaMKⅡand enhances cisplatin resistance.FAK and CaMKⅡshape immune cell infiltration and responses in tumor microenvironments,thereby serving as potential targets for hepatoblastoma.

Ca and Sr co-doping induced oxygen vacancies in 3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts for boosting low-temperature oxidative coupling of methane

It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.

Spectral Properties and Sensitization of Ce^(3+) and Eu^(2+) Codoped Calcium Zinc Chlorosilicate

The Ce^3+ and Eu^2+ ions codoped calcium zinc chlorosilicate Ca_8Zn(SiO_4)_4Cl_2 phosphors have been synthesized for the first time. The diffuse reflection, excitation and emission spectra of Ca_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ have been measured at room temperature. The luminescence sensitizaiton of Eu^2+ by Ce^3+ inCa_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ has been expounded under the excitation of ultraviolet light and the efficient nonradiative energy transfer from Ce^3+ to Eu^2+ in this system is confirmed.

水溶液环境下手性配合物Phe·Ca^(2+)对映异构机理的DFT研究

采用DFT(density functional theory)的M06-2X、MN15方法和处理溶剂效应的SMD模型方法,研究了水溶液中S-苯丙氨酸(S-Phe)与二价钙(Ca^(2+))配合物(Phe·Ca^(2+))的对映异构。反应通道研究发现,S-Phe·Ca^(2+)的对映异构可在质子以N和O分别为桥以及O和N联合为桥迁移的3个通道上实现。计算表明:最优势通道是质子以N为桥迁移,隐性水溶剂效应下决速步自由能垒是227.5 kJ/mol,显性水溶剂效应下该能垒降至108.0~117.6 kJ/mol。结果表明:水溶液中手性Phe·Ca^(2+)的消旋过程十分缓慢,将其用于生命体同补苯丙氨酸和钙元素可能比较安全。

抑制IP3R-Ca^(2+)途径对对乙酰氨基酚所致肝损伤及其线粒体内质网结构偶联的影响

目的探讨抑制肌醇-1,4,5-三磷酸受体(IP3R)-Ca^(2+)途径对对乙酰氨基酚(APAP)所致肝损伤及其线粒体内质网结构偶联(MAMs)的影响。方法40只SPF级雄性C57BL/6小鼠随机分为正常对照组、模型组、IP3R抑制剂(2-APB)组、钙离子螯合剂(BAPTA-AM)组,每组10只。模型组、2-APB组、BAPTA-AM组单次腹腔注射APAP(300 mg/kg)。注射APAP前30 min,2-APB组腹腔注射2-APB(20 mg/kg),BAPTA-AM组腹腔注射BAPTA-AM(2.5 mg/kg)。腹腔注射APAP 24 h后处死各组小鼠。测定血清丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)水平;HE染色观察肝脏病理变化;透射电镜观察肝细胞中线粒体、内质网结构及MAMs变化;测定肝组织匀浆中的Ca^(2+)水平;Western blot测定肝组织中线粒体融合蛋白1(MFN1)、线粒体融合蛋白2(MFN2)、1,4,5-三磷酸肌醇受体1(IP3R1)、葡萄糖调节蛋白75(GRP75)蛋白表达水平。结果与正常对照组相比,模型组小鼠血清ALT及AST水平有所升高(P<0.01),肝脏组织病理学可见肝细胞排列紊乱,并出现肝细胞变性、小叶中心性坏死;透射电镜示线粒体嵴断裂、消失,内质网肿胀断裂,MAMs数量增加;肝组织匀浆中Ca^(2+)含量增加(P<0.01);MFN1、MFN2蛋白表达降低(P<0.01),IP3R1及GRP75蛋白表达增加(P<0.01)。与模型组相比,2-APB组和BAPTA-AM组小鼠血清ALT、AST水平下降(P<0.01),肝脏病理变化明显改善,MAMs减少,肝组织匀浆中Ca^(2+)含量减少(P<0.01),MFN1、MFN2的蛋白表达水平上调(P<0.01),IP3R1及GRP75蛋白表达降低(P<0.01)。结论抑制IP3R-Ca^(2+)途径可以保护APAP所致的肝损伤,其机制与降低肝脏Ca^(2+)水平、减少MAMs数量、调节MAMs相关蛋白的表达有关。

粒度和温度对纳米Ca(OH)_(2)溶解行为的影响

以微米级到纳米级的Ca(OH)_(2)粉末作为原料,采用pH玻璃电极的测试方法分析粉末粒度和溶解温度对Ca(OH)_(2)溶解过程的影响。研究表明:溶解过程在表面反应控制条件下,拟合得到的表观溶解速率常数随着粒度的减小而增大,当溶解温度由25℃增加到55℃、平均粒度由3.81μm降低到56.47 nm时,Ca(OH)_(2)的表观溶解速率常数从6.17×10^(-4)mol/(L·s)增加到了2.01×10^(-3)mol/(L·s),Ca(OH)_(2)的表观溶解反应级数为1.78;当温度分别为25℃、35℃、45℃、55℃时,粒度与表观溶解速率常数呈函数关系。利用Arrhenius方程回归获得平均粒度为3.81μm、0.82μm、78.90 nm、56.47 nm的Ca(OH)_(2)粉末在25~55℃条件下的表观溶解活化能分别为31.99 kJ/mol、31.73 kJ/mol、27.55 kJ/mol、17.80 kJ/mol。纳米Ca(OH)_(2)溶解能够在更短的时间达到较高的pH值,有提高根管消毒效率的可能。

三元材料LiNi_(0.7)Co_(0.15)Mn_(0.15)O_(2)的制备及Ca^(2+)掺杂改性

高镍三元正极材料LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)(NCM,x≥0.6)具有能量密度高、成本合理等优势,是目前最具发展潜力的锂离子电池正极材料之一.然而,NCM在高截止电压下(≥4.3V)会出现加剧的不可逆相变、阳离子混排及过渡金属溶出等问题,这极大地阻碍了其商业化进程.本文中选用Ca^(2+)对LiNi_(0.7)Co_(0.15)Mn_(0.15)O_(2)(NCM70)材料进行掺杂改性,采用共沉淀法制备出前驱体LiNi0.7Co0.15Mn0.15(OH)2,随后通过高温固相法合成不同Ca^(2+)掺杂量的NCM70正极材料,并探究了Ca^(2+)掺杂量对材料晶体结构、表面形貌、电化学性能的影响及其失效机制.结果表明:与本体NCM70材料相比,Ca^(2+)掺杂改性的样品电化学性能得到显著提升;当掺杂量为0.5%时,NCM70-0.5%Ca材料具有最优的改性效果,它在倍率1 C、电压2.95~4.5 V下,首圈放电比容量为181.2 mAh/g, 150圈循环后仍维持其初始容量的71.3%.

K+alkalization promoted Ca2+intercalation in V2CTx MXene for enhanced Li storage

Although MXenes is highly attractive as anode materials of lithium ion batteries,it sets a bottleneck for higher capacity of the V2CTxMXene due to the limited interlayer space and the derived surface terminations.Herein,the cation intercalation and ion-exchange were well employed to achieve a K+and Ca2+intercalated V2CTxMXene.A larger interlayer distance and low F surface terminations were thereof obtained,which accelerates the ion transport and promotes the delicate surface of V2CTx MXene.As a result,a package of enhanced capacity,rate performance and cyclability can be achieved.Furthermore,the ion exchange approach can be extended to other 2 D layered materials,and both the interlayer control and the surface modification will be achieved.

Simultaneous CO_(2) capture and thermochemical heat storage by modified carbide slag in coupled calcium looping and CaO/Ca(OH)2 cycles

The simultaneous CO_(2) capture and heat storage performances of the modified carbide slag with byproduct of biodiesel were investigated in the process coupled calcium looping and CaO/Ca(OH)2 thermochemical heat storage using air as the heat transfer fluid.The modified carbide slag with by-product of biodiesel exhibits superior CO_(2) capture and heat storage capacities in the coupled calcium looping and heat storage cycles.The hydration conversion and heat storage density of the modified carbide slag after 30 heat storage cycles are 0.65 mol·mol^(-1) and 1.14 GJ·t^(-1),respectively,which are 1.6 times as high as those of calcined carbide slag.The negative effect of CO_(2) in air as the heat storage fluid on the heat storage capacity of the modified carbide slag is overcome by introducing CO_(2) capture cycles.In addition,the CO_(2) capture reactivity of the modified carbide slag after the multiple calcium looping cycles is enhanced by the introduction of heat storage cycles.By introducing 10 heat storage cycles after the 10th and 15th CO_(2) capture cycles,the CO_(2) capture capacities of the modified carbide slag are subsequently improved by 32%and 43%,respectively.The porous and loose structure of modified carbide slag reduces the diffusion resistances of CO_(2) and steam in the material in the coupled process.The formed CaCO_(3)in the modified carbide slag as a result of air as the heat transfer fluid in heat storage cycles decomposes to regenerate CaO in calcium looping cycles,which improves heat storage capacity.Therefore,the modified carbide slag with by-product of biodiesel seems promising in the coupled calcium looping and CaO/Ca(OH)_(2) heat storage cycles.

Altered expression of stromal interaction molecule(STIM)-calcium release-activated calcium channel protein(ORAI) and inositol1,4,5-trisphosphate receptors(IP_3Rs)in cancer:will they become a new battlefield for oncotherapy?

The stromal interaction molecule(STIM)-calcium release-activated calcium channel protein(ORAI) and inositol1,4,5-trisphosphate receptors(IP_3Rs) play pivotal roles in the modulation of Ca^(2+)-regulated pathways from gene transcription to cell apoptosis by driving calcium-dependent signaling processes.Increasing evidence has implicated the dysregulation of STIM-ORAI and IP_3Rs in tumorigenesis and tumor progression.By controlling the activities,structure,and/or expression levels of these Ca^(2+)-transporting proteins,malignant cancer cells can hijack them to drive essential biological functions for tumor development.However,the molecular mechanisms underlying the participation of STIM-ORAI and IP_3Rs in the biological behavior of cancer remain elusive.In this review,we summarize recent advances regarding STIM-ORAI and IP_3Rs and discuss how they promote cell proliferation,apoptosis evasion,and cell migration through temporal and spatial rearrangements in certain types of malignant cells.An understanding of the essential roles of STIM-ORAI and IP_3Rs may provide new pharmacologic targets that achieve a better therapeutic effect by inhibiting their actions in key intracellular signaling pathways.

不同补钙方式对固定献血者血清Ca^(2+)及PTH的影响分析

目的探讨不服钙剂、口服葡萄糖酸钙、口服乳酸钙颗粒三种情况对于固定单采血小板献血者血清钙(Ca^(2+))、血清甲状旁腺素(PTH)和献血不良反应的影响,比较哪种钙剂的效果更好。方法2020年7月—9月从本中心固定献血者人群中招募35名志愿者(男性21名,女性14名)共同参与三组实验:第一组实验为对照组,即在单采血小板前不予补充钙剂;第二组在采前20 min(采样后)补充10%葡萄糖酸钙口服液;第三组在采前20 min(采样后)补充乳酸钙颗粒。三组实验中,每一组都分别在采样时(采前20 min)、穿刺时(采集0 min)、采集初中期(采集20 min)、采集中后期(采集40 min)留取全血标本5 mL用于血清Ca^(2+)和血清PTH的检测。比较三组血清Ca^(2+)和血清PTH数值的变化趋势,探讨钙剂的作用效果。结果献血者血清Ca^(2+)随时间的改变在显著变化(F=101.979,P<0.001),组间效应不显著(F=0.059,P=0.943>0.05);血清PTH随时间的改变在显著变化(F=495.834,P<0.001),组间效应不显著(F=1.241,P=0.294>0.05);血清Ca^(2+)和血清PTH数值随采血时间的变化成负相关。两种钙剂均能减少枸橼酸盐反应的发生概率(P<0.001)。结论无论是否预防性补充钙剂,或是补充何种钙剂,献血者体内血清Ca^(2+)均能够在PTH的作用下保持稳定;预防性补充钙剂可以降低枸橼酸盐反应发生率。

EFFECT OF ELECTROACUPUNCTURE AND CALCIUM-CHANNEL INHIBITORS ON CYTOPLASMIC FREE CALCIUM CONCENTRATION OF MOUSE BRAIN CELLS

Objective: To study the effect of electroacupuncture (EA) and Verapamil and Nifedipine (calcium channel inhibitors) on free calcium concentrations of cells and intrasynaptosomes in hypothalamus (HT), periaqueductual grey matter (PAG) and hippocampus (HIP) of mice. Methods: The female ICR mice were randomly divided into control, EA, CaCl2 and CaCl2+EA groups (n=8 in each group). Pain threshold was detected by using radiation-heat irradiation-induced tail flick method. EA (8 Hz, a suitable stimulating strength, dense-sparse waves and duration of 30 min) was applied to“Shuigou” (水沟 GV 26) and “Chengjiang” (承浆CV 24). CaCl2 (10 μL, 0.2 μmol/L) was injected into the lateral cerebral ventricle of mice after EA. The concentrations of cytosolic free calcium ([Ca 2+]i) in HIP, PAG, HT cell suspension specimen and hippocampal intrasynaptosome suspension of mice were determined by the fluorescent calcium indicator Fura-2-AM and a spectrofluorometer. Results: During EA analgesia, the intracellular free [Ca 2+]i in HT and PAG specimens and intrsynaptosomal [Ca 2+]i of the 3 cerebral regions decreased considerably (P<0.05～0.01), but that in hippocampal cell suspension increased significantly (P<0.01) in comparison with control group. The concentrations of hippocampal intrasynaptosomal free [Ca 2+]i decreased significantly after adding Verapamil and Nifedipine to the extracted hippocampal intrasynaptosomal specimen. Microinjection of CaCl2 into lateral ventricle had no apparent influence on degree of analgesia (DA)% and intracellular and intrasynapsotomal [Ca 2+]i, but significantly lower DA% and reduce changes of cytosolic and intrasynaptosomal [Ca 2+]i induced by EA stimulation. Conclusion: Calcium ion in the neurons and intrasynaptosome of HT, PAG and HIP is involved in electroacupuncture analgesia.

Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid–nitric acid aqueous solution by strong acid cation resin

The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.

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.

Caribbean maitotoxin elevates [Ca^(2+)]i and activates non-selective cation channels in HIT-T15 cells

AIM:To investigate the cytotoxic mechanism of caribbean maitotoxin(MTX-C) in mammalian cells.METHODS:We used whole-cell patch-clamp techniques and fluorescence calcium imaging to determine the cellular toxic mechanisms of MTX-C in insulin secreting HIT-T15 cells,which is a system where the effects of MTX have been observed.HIT-T15 cells stably express L-type calcium current,making it a suitable model for this study.Using the fluorescence calcium indicator Indo-1 AM,we found that there is a profound increase in HIT-T15 intracellular free calcium 3 min after application of 200 nmol/L MTX-C.RESULTS:About 3 min after perfusion of MTX-C,a gradual increase in free calcium concentration was observed.This elevation was sustained throughout the entire recording period.Application of MTX-C did not elicit the L-type calcium current,but large cationiccurrents appeared after applying MTX-C to the extracellular solution.The current-voltage relationship of the cation current is approximately linear within the voltage range from-60 to 50 mV,but flattened at voltages at-80 and-100 mV.These results indicate that MTX-C induces a non-voltage activated,inward current under normal physiological conditions,which by itself or through a secondary mechanism results in a large amount of cationic influx.The biophysical mechanism of MTX-C is different to its isoform,pacific maitotoxin(MTX-P),when the extracellular calcium is removed.CONCLUSION:We conclude that MTX-C causes the opening of non-selective,non-voltage-activated ion channels,which elevates level of intracellular calcium concentration and leads to cellular toxicities.

Role of Calcium Ion in Apoptosis of MD Cancer Cells Induced by Arsenic Trioxide

In order to observe the role of calcium ion in apoptosis of MD cancer cells induced by arsenic trioxide, inhibition percentage was detected by MTT assay; morphology changes were examined by fluorescence microscope; apoptosis was examined by DNA Ladder; [Ca^2＋]i was investigated by spectrofluorimeter in vitro on MDCC-MSB 1 cells. The results showed that As2O3 inhibited the proliferation of MDCC-MSB1 cells in concentration dependent manner （P〈0.05 or P〈0.01）; typical apoptosis character was observed by fluorescence microscope; DNA Ladder was observed; the [Ca^2＋]i was elevated significantly after the treatment of As203 （P〈0.05 or P〈0.01） and showed a dose-dependent manner. It is concluded that the calcium may play an important role in apoptosis of MD cancer cells induced by arsenic trioxide.

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.

Intestinal Ca2+ absorption revisited: A molecular and clinical approach

Ca2+has an important role in the maintenance of the skeleton and is involved in the main physiological processes.Its homeostasis is controlled by the intestine,kidney,bone and parathyroid glands.The intestinal Ca2+absorption occurs mainly via the paracellular and the transcellular pathways.The proteins involved in both ways are regulated by calcitriol and other hormones as well as dietary factors.Fibroblast growth factor 23(FGF-23)is a strong antagonist of vitamin D action.Part of the intestinal Ca2+movement seems to be vitamin D independent.Intestinal Ca2+absorption changes according to different physiological conditions.It is promoted under high Ca2+demands such as growth,pregnancy,lactation,dietary Ca2+deficiency and high physical activity.In contrast,the intestinal Ca2+transport decreases with aging.Oxidative stress inhibits the intestinal Ca2+absorption whereas the antioxidants counteract the effects of prooxidants leading to the normalization of this physiological process.Several pathologies such as celiac disease,inflammatory bowel diseases,Turner syndrome and others occur with inhibition of intestinal Ca2+absorption,some hypercalciurias show Ca2+hyperabsorption,most of these alterations are related to the vitamin D endocrine system.Further research work should be accomplished in order not only to know more molecular details but also to detect possible therapeutic targets to ameliorate or avoid the consequences of altered intestinal Ca2+absorption.

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.

Ablation of TRPV4 in HepG2 with Its CRISPR/Cas9 Enhances Its Wound Healing

TRPV4 activity modulates cell activities including receptor trafficking and transcriptional or translational regulations. We tested its CRISPR/Cas9 scissor efficacy in HepG2 (HEK293) cell noticed that it worked well in both cell lines to eliminate TRPV4 genome sequences. To confirm TRPV4 functions in the cell morphology maintenance and cell growth (beyond Ca2+ channel), we compared its wound healing, cell surface area, survival property and soft agar growth ability after deletion of TRPV4 gene in the cells with its CRISPR/Cas9 system. With these experiments, we confirmed that TRPV4 is required not only to function as Ca2+ channel but also to maintain its proper cell morphology as a corner stone protein on the cell adhesion junction.