NMDA受体介导脑缺血/再灌注诱导GluR6 巯基亚硝基化的研究

目的:研究脑缺血再灌注以及联合给予脑缺血和NMDA(N-甲基-D-天冬氨酸)受体抑制剂MK801对大鼠海马CA1区Glu R6巯基亚硝基化以及海马CA1区锥体细胞凋亡的影响。方法:采用四动脉结扎法构建大鼠全脑缺血再灌注模型,给予SD大鼠腹腔注射NMDA受体特异性抑制剂MK801(3 mg/kg)。主要运用'生物素转化法'(Biotin-Switch method)、SDS-PAGE、免疫印迹、焦油紫染色等方法对Glu R6的巯基亚硝基化(S-亚硝基化)、蛋白表达水平以及海马CA1区锥体细胞的凋亡水平进行研究。结果:脑缺血/再灌注显著促进Glu R6的巯基亚硝基化以及海马CA1区锥体细胞的凋亡,给予NMDA受体特异性抑制剂MK801能够显著抑制脑缺血/复灌诱导增加的Glu R6的S-亚硝基化以及海马CA1区锥体细胞的凋亡。结论:脑缺血/再灌注早期NMDA受体介导了Glu R6的巯基亚硝基化以及海马CA1区锥体细胞的凋亡,从而为临床治疗缺血再灌注脑损伤提供了理论依据。     

水杨酸钠对小鼠下丘核神经元GABAα、NR1表达及听反应的影响

目的:探讨水杨酸钠给药对小鼠下丘核神经元GABAα、NR1表达及听反应的影响。方法:实验将36只成年健康昆明小鼠分三组(n=12):A组:对照组;B组:水杨酸钠给药组(450mg.kg-1.d-1);C组:水杨酸钠(450mg.kg-1.d-1)+利多卡因(10mg.kg-1.d-1)组。各组均经腹腔注射给药,A组给以同等剂量的生理盐水,所有动物自由饮食。给药15 d后进行检测。采用RT-PCR技术检测小鼠下丘核区GABAα、NR1mRNA的表达;采用细胞外电生理记录技术研究下丘核区神经元在水杨酸钠给药后强度-发放率函数、强度-潜伏期函数和频率调谐曲线的变化。结果:①水杨酸钠组的下丘核区GABAαmRNA表达较对照组明显降低(P<0.05);水杨酸钠+利多卡因组与对照组比较无显著性差异(P>0.05);水杨酸钠组NR1mRNA表达较对照组明显升高(P<0.01),水杨酸钠+利多卡因组与对照组比较有显著性差异(P<0.05);②水杨酸钠给药后发放率和潜伏期函数呈非单调性改变,而神经元的调谐曲线从狭窄型向宽阔型转变;③水杨酸钠+利多卡因组发放率和潜伏期函数呈非单调性改变,而神经元的调谐曲线从狭窄型向宽阔型转变例数显著减少(P<0.05,P<0.01)。结论:①水杨酸钠引起实验小鼠下丘核GABAαmRNA表达下调,同时又使小鼠下丘核NR1mRNA表达增高;②水杨酸钠给药后发放率和潜伏期函数呈非单调性改变,而神经元的调谐曲线从狭窄型向宽阔型转变③利多卡因有逆转水杨酸钠给药后发放率和潜伏期函数呈非单调性改变和神经元的调谐曲线从狭窄型向宽阔型转变的作用。     

钙蛋白酶抑制剂Calpeptin在脓毒症膈肌功能障碍中的作用研究

摘要 目的：探究钙蛋白酶抑制剂Calpeptin在脓毒症膈肌功能障碍中的保护作用及其分子机制。方法：通过腹腔内注射8 mg/kg LPS的方法构建大鼠脓毒症模型,将雄性SD大鼠分为3组（n=6/组）：正常对照组（Con组）、脓毒症组（Sepsis组）和钙蛋白酶抑制剂预处理组（Calpeptin组）。处死大鼠,快速分离大鼠膈肌组织,采用苏木精-伊红(HE)染色法检测膈肌组织病理学改变,通过实时荧光定量PCR法（qRT-PCR）分别检测膈肌组织中钙蛋白酶μ-Calpain、凋亡相关基因天冬氨酸特异性半胱氨酸蛋白酶-3（Caspase-3）、自噬相关蛋白Beclin-1、肿瘤坏死因子-α（TNF-α）和白介素-6（IL-6）mRNA表达水平。结果：与正常对照组相比,LPS处理24 h的脓毒症组大鼠膈肌组织HE染色未见明显膈肌萎缩改变,但膈肌收缩力下降,这与我们以往的研究结果一致。qRT-PCR法检测到脓毒症组大鼠膈肌组织中上述基因mRNA表达量明显增加（P<0.05）,而Calpeptin预处理后,上述基因mRNA表达水平显著下降（P<0.05）。结论：脓毒症时膈肌发生功能障碍,钙蛋白酶抑制剂Calpeptin可显著减轻LPS诱导的炎症、凋亡、自噬的激活。     

miR-487b在改善慢性心力衰竭中的作用机制

为了考察miR-487b在慢性心力衰竭发病过程中的作用及机制,本研究检测了miR-487b在慢性心力衰竭患者中的表达情况,通过冠状动脉左前降支结扎建立大鼠心力衰竭模型,并通过转染miR-487b模拟物和miR-487b抑制剂来调控其表达。研究发现,慢性心力衰竭患者心肌组织中mir-487b的表达水平显著低于健康人(p0.05)。此外,慢性心力衰竭模型大鼠心肌组织中miR-487b的表达也显著下调(p0.05)。上调miR-487b则有效抑制了慢性心力衰竭大鼠心肌细胞肥大,减少了胶原纤维和炎症细胞浸润程度(p0.05)。上调miR-487b还有效减少了心肌细胞凋亡(p0.05)。上调miR-487b则可显著升高大鼠心肌组织中SOD水平并降低MDA水平。采用ELISA法检测慢性心力衰竭患者和健康人血清中IL-33和ST2的水平,发现慢性心力衰竭患者和大鼠中的IL-33和ST2的水平均显著升高。此外,上调miR-487b可显著抑制IL-33和ST2mRNA和蛋白的表达。本研究表明miR-487b在慢性心力衰竭患者和大鼠中均显著下调;上调miR-487b的表达可显著改善慢性心力衰竭大鼠的心脏功能,抑制心肌纤维化和细胞凋亡,提高抗氧化能力;miR-487b可能通过抑制IL-33/ST2信号通路来发挥心脏保护作用。     

雌激素快速影响大鼠发育期海马NMDA受体活性的机制

为了探讨雌激素对发育期大鼠海马NMDA受体活性的快速影响,对出生后18d的雄性大鼠进行苯甲酸雌二醇皮下注射,1h后用WesternBlot检测海马NMDA受体NR1和NR2B亚基、雌激素β受体、ERK1/2蛋白的表达,以及NR2B和ERK1/2的磷酸化水平;并通过海马内给予雌激素受体拮抗剂ICI182,780和MEK1/2抑制剂U0126预处理,进一步分析苯甲酸雌二醇影响NR2B和ERK1/2磷酸化的作用机制。结果显示,苯甲酸雌二醇不影响NR1、NR2B、ERβ和ERK1/2的表达,但能快速增强NR2B和ERK1/2的磷酸化水平。雌激素受体拮抗剂ICI182,780和MEK1/2抑制剂U0126均能明显抑制苯甲酸雌二醇诱导的NR2B和ERK1/2磷酸化水平的增加。以上结果提示,雌激素可能通过雌激素受体的非基因组机制激活ERK/MAPK信号转导通路,快速诱导NMDA受体NR2B亚基磷酸化,激活NMDA受体。     

NMDA受体通道参与大鼠脊髓背角C纤维诱发电位LTP的表达

以往研究表明,激动NMDA受体是引起海马长时程增强(LTP)的必备条件,而LTP的表达主要与AMPA受体的磷酸化及其受体组装到突触后膜有关.但是,近年来有研究表明NMDA受体通道也参与了LTP的表达.为探讨NMDA受体通道是否参与了脊髓背角C纤维诱发电位LTP的表达,诱导LTP后,分别静脉或脊髓局部给予NMDA受体拮抗剂MK801或APV,观察其作用.发现静脉注射非竞争性NMDA受体MK801(0.1mg/kg)对脊髓LTP无影响,注射0.5mg/kg显著抑制LTP,但是当剂量增高到1.0mg/kg时,抑制作用并未进一步增大.脊髓局部给予MK801也能抑制脊髓背角LTP.为验证上述结果,使用了竞争性NMDA受体拮抗剂APⅤ.结果显示,脊髓局部给予50μmol/LAPⅤ对LTP无影响,100μmol/L对LTP有显著的抑制作用,当浓度升至200μmol/L时,抑制作用并未见进一步增强.因此认为,NMDA受体通道部分地参与了脊髓背角C纤维诱发电位LTP的表达.     

癫痫大鼠海马NMDA受体亚基NR2A和BDNFmRNA水平的检测

目的通过锂一匹罗卡品癫痫模型（ithium—pilocarpine seizures rats model of epilepsy,LPS）,研究NMDA受体亚基NR2A、BDNF mRNA的表达,探讨NR2A、BDNF在LPS中的作用。方法建立氯化锂-匹罗卡品大鼠模型,运用原位杂交技术检测致痫后各组不同时间点海马CAI、CA3及DG区NR2A与BDNF mRNA的表达。结果LPS海马NR2A、BDNF mRNA在各观察时间点及部位模型组与正常对照组比较均有明显上调,且有显著统计学差异（P〈0．05）。模型组NR2A mRNA的表达上调7d达峰值（P〈0．05）;而BDNF mRNA表达上调14d达峰值。VPA干预组NR2A mRNA在大鼠海马不同时间及部位（除1d的CA3区）的表达较模型组明显下调（P〈0．05）;BDNF mRNA在大鼠海马不同时间及部位（除28d的DG区）的表达较模型组明显下调（P〈0．05）。结论锂－匹罗卡品腹腔注射可诱导大鼠海马NR2A和BDNF mRNA的表达明显上调;NR2A mRNA表达的增强可能是诱导调控BDNF mRNA表达增强的重要机制之一,说明NMDA受体亚基NR2A可能成为抑制癫痫发作的新靶点。     

不同训练方式建立大鼠空间记忆后海马结构NMDA受体表达的变化

短期强化训练能否建立可靠的空间长时记忆？用不同训练方式建立空间记忆后,大鼠海马结构NMDA受体的表达发生怎样的变化？目前尚未见明确报道。本研究应用Morris水迷宫方法分别采用以下模式对大鼠进行训练：空间长时记忆训练模式（LT组）、空间短时记忆训练模式（ST组）以及短期强化训练模式（SRT组）,对不同训练模式建立的空间记忆进行了比较,应用免疫荧光组织化学方法检测各组大鼠海马结构NMDA／NR1受体表达的变化。结果表明,Morris水迷宫训练过程中,LT和SRT组大鼠寻找站台的半均潜伏期和策略均无显著性差异：记忆检测发现,除LT组大鼠在站台所在象限的停留时间明显长于SRT组大鼠外,两组大鼠寻找站台的潜伏期和策略以及穿越站台的次数均无显著性差异。ST组大鼠海马结构NMDA／NR1的免疫反应强度与对照组相比,无显著差异。但是,LT和SRT组大鼠海马CA1区锥体细胞联及齿状回的颗粒细胞层NMDA／NR1免疫荧光反应都明显增强,两组之间比较无显著差异,但是两组分别与对照组和ST组相比均有显著性差异。上述结果提示,短期强化训练可建立与长期训练基本相同的空间长时记忆。大鼠海马结构CA1区和齿状回NMDA受体表达的增加,可能是空间长时记忆形成的机制之一。     

生后早期听觉剥夺、经验改变大鼠听皮层NMDA受体NR2B蛋白表达

应用蛋白质印迹检测技术,研究早期听觉剥夺、经验对大鼠听皮层NMDA受体NR2B蛋白表达的影响.结果表明,听觉剥夺使生后14天龄组和28天龄组动物听皮层NR2B蛋白表达水平明显下降(P<0.05,P<0.01),听觉剥夺7天后再给予纯音暴露则又使NR2B表达水平明显提高(P<0.05),呈现双向调节趋势.听觉剥夺和纯音暴露对生后42天龄组大鼠听皮层NR2B表达不再产生明显调节作用(P>0.05).结果提示,在大鼠生后发育关键期,听觉剥夺、经验可改变听皮层NMDA受体NR2B蛋白表达水平.研究结果为研究感觉功能发育可塑性的机制提供了重要实验资料.     

水杨酸钠对小鼠下丘核神经元γ-氨基丁酸和谷氨酸表达及听反应特性的影响

本研究探讨水杨酸钠对小鼠下丘核神经元γ-氨基丁酸（γ-aminobutyricacid,GABA）、谷氨酸（glutamate,Glu）表达及听反应的影响。36只成年健康昆明小鼠分为三组（每组12只）：对照组;NaSA组（水杨酸钠给药何天450mg／kg）;NaSA＋lidocaine组（水杨酸钠给药每天450mg/kg＋利多卡因给药每天10mg／kg）。各组均经腹腔注射给药,对照组给以同等剂量的生理盐水。给药15d后,免疫组织化学方法检测下丘核区神经元GABA、Glu的表达;细胞外电生理记录技术观察下丘核区神经元强度-发放率函数、强度-潜伏期函数和频率-调谐曲线的变化。结果如下：（1）NaSA组与NaSA＋lidocaine组GABA表达明显较对照组降低,但该两组比较无显著性差异;NaSA组Glu表达较对照组和NaSA＋lidocaine组明显增加,NaSA＋lidocaine组与对照组比较无显著性差异。（2）NaSA组强度-发放率函数呈低强度时上移,高强度时下降的非单调性改变;强度-潜伏期函数下移;调谐曲线从狭窄型向宽阔型转变。（3）NaSA＋lidocaine给药后强度-发放率函数无非单调性改变现象,强度-潜伏期函数下移的程度较NaSA组明显减轻,而神经元的调谐曲线从狭窄型向宽阔型转变例数也显著减少。以上结果提示：水杨酸钠能增强Glu阳性神经元表达,但抑制GABA阳性神经元表达;水杨酸钠可影响下丘核神经元的听反应特性,强度-发放率函数呈非单调性变化,强度-潜伏期函数下移,调谐曲线尖部变宽。利多忙因有逆转水杨酸钠改变下丘核神经元听反应的作用。     

Cross-talk Between Calpain and Caspase-3 in Penumbra and Core During Focal Cerebral Ischemia-reperfusion

Aims Some data have shown the functional connection between calpain and caspase-3. Here, we investigated the cross-talk between calpain and caspase-3 in penumbra and core during focal cerebral ischemia-reperfusion. Methods The activities of calpain and the levels of calpastatin, microtubule-associated protein-2 (MAP-2), and spectrin in penumbra and core at 3 or 23 h of reperfusion (R 3 h or R 23 h) after 1-h focal cerebral ischemia in rats were determined in sham- or caspase-3 inhibitor z-DEVD-CHO-treated rats.On the other hand, the determination of the activities of caspase-3 and the levels of MAP-2 and spectrin was done in sham- or calpain-inhibitor I-treated rats. Results z-DEVD-CHO (600 ng/rat, i.c.v.) markedly reduced the μ- and m-calpain activities in penumbra and the m-calpain activities in core at R 3 h and R 23 h, and enhanced the calpastatin levels in penumbra at R 3 h and in core at R 3 h and R 23 h significantly; however, it had no significant effects on the μ-calpain activities in core and the calpastatin levels in penumbra at R 23 h. Calpain inhibitor I (0.8 mg/rat, i.c.v.) markedly reduced the caspase-3 activities in core at R 3 h and R 23 h, but not in penumbra. Both calpain and caspase-3 inhibitors increased the levels of MAP-2 and spectrin in penumbra and core significantly after focal cerebral ischemia-reperfusion. Conclusions Our data provide direct evidence to demonstrate the cross-talk between calpain and caspase-3 in penumbra and core during focal cerebral ischemia-reperfusion.     

Calpain inhibition delays neutrophil apoptosis via cyclic AMP-independent activation of protein kinase A and protein kinase A-mediated stabilization of Mcl-1 and X-linked inhibitor of apoptosis (XIAP)

Human neutrophils underwent spontaneous apoptosis, which was accompanied with proteasome-mediated degradation of Mcl-1 and X-linked inhibitor of apoptosis (XIAP). Calpain inhibitors (PD150606 and N-acetyl-Leu-Leu-Nle-CHO) prevented spontaneous neutrophil apoptosis and degradation of Mcl-1 and XIAP, and the effects of calpain inhibitors on neutrophils were resistant to cycloheximide. Calpain inhibitors induced protein kinase A (PKA) activation, which was unaccompanied with an increase in intracellular cyclic AMP. Calpain inhibition-mediated delayed neutrophil apoptosis, stabilization of Mcl-1 and XIAP, and phosphorylation of PKA substrates were suppressed by H-89 (specific PKA inhibitor). These findings suggest that calpain inhibition delays neutrophil apoptosis via cyclic AMP-independent activation of PKA and PKA-mediated stabilization of Mcl-1 and XIAP.     

The role of calpain in the regulation of ADAM17-dependent GPIbα ectodomain shedding

There are evidence that both a disintegrin and metalloproteinase 17 (ADAM17) and calpain are involved in platelet glycoprotein (GP)Ibα ectodomain cleavage. However, the relationship between the two enzymes in the shedding process remains unclear. Here we show that calcium ionophore A23187- and α-thrombin-induced GPIbα shedding is completely inhibited by the metalloproteinase inhibitor GM6001, whereas it is only partially inhibited by calpain inhibitors. Calpain activator dibucaine-induced GPIbα shedding was completely inhibited by both metalloproteinase and calpain inhibitors. On the other hand, calpain inhibitors did not inhibit GPIbα shedding induced by the reagents that specifically activate ADAM17. Furthermore, A23187-induced GPIbα shedding in Chinese hamster ovary cells expressing wild-type or mutant GPIb-IX was also partially inhibited by calpain inhibitors and almost completely inhibited by GM6001. Therefore, these data indicate that calpain plays an important role in the regulation of ADAM17-dependent GPIbα ectodomain shedding in both platelets and nucleated cells.     

Apoptosis-suppressing and autophagy-promoting effects of calpain on oridonin-induced L929 cell death

Calpain, calcium-dependent cysteine protease, is reported here to impose the crucial influence on oridonin-induced L929 cell apoptosis and autophagy. We found that inhibition of calpain increased oridonin-induced Bax activation, cytochrome c release and PARP cleavage, indicating that calpain plays an anti-apoptotic role in oridonin-induced L929 cell apoptosis. To explore this potential anti-apoptotic mechanism, we inhibited calpain and proteasome activity in oridonin-induced L929 cell apoptosis, and discovered that the inducible IκBα proteolysis was partially blocked by the inhibition of either calpain or proteasome, but completely blocked by the inhibition of both. It demonstrated that calpain and proteasome were two distinct pathways participating in IκBα degradation. To further study the role of calpain in oridonin-induced L929 cell autophagy, we discovered that calpain inhibitor decreased oridonin-induced autophagy, as well as Beclin 1 activation and the conversion from LC3-I to LC3-II. Moreover, Inhibition of autophagy by 3-MA increased oridonin-induced apoptosis. In conclusion, besides suppressing apoptosis, calpain promotes autophagy in oridonin-induced L929 cell death, and inhibition of autophagy might contribute to up-regulation of apoptosis.     

Contribution of NMDA and Non-NMDA Receptors to In vivo Glutamate-Induced Calpain Activation in the Rat Striatum. Relation to Neuronal Damage

Glutamate, the major excitatory neurotransmitter, can cause the death of neurons by a mechanism known as excitotoxicity. This is a calcium-dependent process and activation of the NMDA receptor subtype contributes mainly to neuronal damage, due to its high permeability to calcium. Activation of calpain, a calcium-dependent cysteine protease, has been implicated in necrotic excitotoxic neuronal death. We have investigated the contribution of NMDA and non-NMDA ionotropic receptors to calpain activation and neuronal death induced by the acute administration of glutamate into the rat striatum. Calpain activity was assessed by the cleavage of the cytoskeletal protein, α-spectrin. Caspase-3 activity was also studied because glutamate can also lead to apoptosis. Results show no caspase-3 activity, but a strong calpain activation involving both NMDA and non-NMDA receptors. Although neuronal damage is mediated mainly by the NMDA receptor subtype, it can not be attributed solely to calpain activity. Special issue article in honor of Dr. Ricardo Tapia.     

Comparison of the Effect of Calpain Inhibitors on Two Extralysosomal Proteinases: The Multicatalytic Proteinase Complex and m-Calpain

Abstract: The potencies of three peptide aldehyde inhibitors of calpain (calpain inhibitors 1 and 2 and calpeptin) as inhibitors of four catalytic activities of the multicatalytic proteinase complex (MPC) were compared with their potencies as inhibitors of m-calpain. The chymotrypsinlike activity (cleavage after hydrophobic amino acids) and the caseinolytic activity (degradation of β-casein) of MPC were strongly inhibited by calpain inhibitors 1 and 2 (IC₅₀ values in the low micromolar range). Cleavage by MPC after acidic amino acids (peptidylglutamyl-peptide bond hydrolyzing activity) and basic amino acids (trypsinlike activity) was inhibited less effectively, declining moderately with increasing concentrations of calpain inhibitors 1 and 2. Calpeptin only weakly inhibited the four MPC activities, yet was the most potent inhibitor of m-calpain. These results indicate that caution must be exercised when calpain inhibitors 1 and 2 are used to infer calpain function. Calpeptin may be a better choice for such studies, although its effect on other cysteine or serine proteinases remains to be determined.     

Glutamate Neurotoxicity Is Independent of Calpain I Inhibition in Primary Cultures of Cerebellar Granule Cells

Glutamate-induced neurotoxicity and calpain activity were studied in primary cultures of rat cerebellar granule neurons and glial cells. Calpain activation, as monitored by quantitative immunoblotting of spectrin, required micromolar concentrations of Ca2+ in neuronal homogenates (calpain I) and millimolar Ca2+ concentrations in glial homogenates (calpain II). Glutamate-induced toxicity and calpain activation were observed in neuronal, but not in glial, cultures. In neurons, calpain I activation by glutamate was dose-dependent and persisted after withdrawal of neurotoxic doses of glutamate. Natural (GM1) and semisynthetic (LIGA4) gangliosides or the glutamate receptor blocker MK-801 prevented calpain I activation and delayed neuronal death elicited by glutamate. GM1 and LIGA4 had no effect on calpain I activity in neuronal homogenates, however. Furthermore, two calpain I inhibitors (leupeptin and N-acetyl-Leu-Leu-norleucinal) prevented glutamate-induced spectrin degradation, but failed to affect glutamate neurotoxicity. These results thus suggest that glutamate-induced neurotoxicity is independent of calpain I activation.     

Neuronal Nitric Oxide Synthase and Calmodulin-Dependent Protein Kinase IIα Undergo Neurotoxin-Induced Proteolysis

Abstract: Calpain (calcium-activated neutral protease) has been implicated as playing a role of neuronal injury in cerebral ischemia and excitotoxicity. Here we report that, in addition to extreme excitotoxic conditions [ N -methyl- d -aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainate challenges], other neurotoxins such as maitotoxin, A23187, and okadaic acid also induce calpain activation, as detected by m-calpain autolytic fragmentation and nonerythroid α-spectrin breakdown. Under the same conditions, calmodulin-dependent protein kinase II-α (CaMPK-IIα) and neuronal nitric oxide synthase (nNOS) are both proteolytically cleaved by calpain. Such fragmentation can be reduced by calpain inhibitors (acetyl-Leu-Leu-Nle-CHO and PD151746). In vitro digestion of protein extract from cortical cultures with purified μ- and m-calpain produced fragmentation patterns for CaMPK-IIα and nNOS similar to those produced in situ. Also, several other calpain-sensitive calmodulin-binding proteins (plasma membrane calcium pump, microtubule-associated protein 2, and calcineurin A) and protein kinase C-α are also degraded in neurotoxin-treated cultures. Lastly, in a rat pup model of acute excitotoxicity, intrastriatal injection of NMDA resulted in breakdown of CaMPK-IIα and nNOS. The degradation of CaMPK-IIα, nNOS, and other endogenous calpain substrates may contribute to the neuronal injury associated with various neurotoxins.     

Calpain inhibitors stimulate phagocyte functions via activation of human formyl peptide receptors

Calpain inhibitors induce pertussis toxin (PTx)-sensitive chemotaxis in human neutrophils and monocytes. Here, we show that various calpain inhibitors (PD150606, PD151746, N-acetyl-Leu-Leu-Nle-CHO [ALLN], N-acetyl-Leu-Leu-Met-CHO [ALLM], and calpeptin) and γ-secretase inhibitor I induced PTx-sensitive increase in cytoplasmic free Ca²⁺ ([Ca²⁺]_i) in human neutrophils and neutrophil migration. HEK-293 cells stably expressing human formyl peptide receptor (hFPR) or hFPR-like 1 (hFPRL1) displayed stimulus-specific increase in [Ca²⁺]_i in response to calpain inhibitors (PD150606, PD151746, ALLN, ALLM, MG-132, and calpeptin), γ-secretase inhibitor I, and N-formyl-Met-Leu-Phe. Parent HEK-293 cells also displayed PTx-sensitive increase in [Ca²⁺]_i in response to calpeptin and γ-secretase inhibitor I, whereas they displayed PTx-resistant increase in [Ca²⁺]_i in response to MG-132. MDL-28170 induced neither an increase in [Ca²⁺]_i in neutrophils and HEK-293 cells nor neutrophil migration. Ionomycin-induced cleavage of talin (a substrate of calpain) in neutrophils was inhibited by all inhibitors used here. These findings suggest that potent calpain inhibitors could stimulate phagocyte functions via activation of hFPR, hFPRL1 and/or other G-protein coupled receptors depending on the inhibitors used.     

Calpain inhibitors regulate the conversion of thyroid gland follicles in rats and humans

Effects of calpain inhibitors on thyroid follicle conversion into monolayer was investigated. Human and rat primary thyroid cultures require the follicular structure after enzyme disaggregation of native tissue fragments. Removal of thyroid-stimulating hormone (TSH) from the culture medium causes migration of thyrocytes from follicles into monolayer, some differences were noted in conversion of rat and human thyroid follicles. The locomotion of rat thyrocytes is observed after preliminary incubation with TSH, but migration of thyrocytes from human thyroid follicles does not require such a preincubation. Phorbol esters induce migration of rat and human thyroid cells. Calpain inhibitors exert a significant influence on locomotion of the thyroid gland cells induced by the removal of TSH from the culture medium. Human thyrocyte migration is markedly inhibited by calpain inhibitor I or II. Likewise, addition of calpain inhibitor I into primary culture of rat thyrocytes decreased the number of migrating cells by 52%, and shortened average migration distance by 34%. Also, calpain inhibitors reduced the speed of phorbol ether-induced conversion of rat and human thyroid follicles into monolayer.