Bcl-2

Bcl - 2
  • 文章类型: Case Reports
    Rosai-Dorfman disease (RDD) is a rare benign condition that presents most commonly with lymphadenopathy and skin lesions and is characterized by infiltration of histiocytes into the skin and soft tissues. We present a case of RDD in an Afro-Caribbean male in his 50s who presented to our chest clinic with shortness of breath, cough, and weight loss of 15 kg over one year. CT scan showed evidence of right pleural effusion, mediastinal and hilar lymphadenopathy, and bony lesions in the spine. Cytology from multiple pleural effusions and endobronchial ultrasound-guided fine needle aspiration from lymph nodes did not show any malignancy. Left axillary excisional biopsy showed a pattern consistent with RDD. The patient was started on interferon therapy by the hematologist and pleurodesis after repeated pleural taps failed to relieve recurrent right pleural effusions. This case emphasizes the importance of tissue diagnosis to avoid misdiagnosis and unnecessary treatment.
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  • 文章类型: Journal Article
    在我们之前的研究中,通过结构修饰合成了3-O-β-D-半乳糖化白藜芦醇(Gal-Res),然后成功制备了3-O-β-D-半乳糖化白藜芦醇聚多巴胺纳米颗粒(Gal-ResNPs),以提高其生物利用度和肝脏分布。然而,Gal-ResNP对肝细胞癌的药效学疗效和具体机制尚不清楚.在这里,通过移植瘤模型成功构建小鼠肝癌模型。Gal-ResNPs(34.2mg/kg)显著抑制肝癌模型小鼠的肿瘤生长,对其体重无显著影响,对主要脏器无明显毒性作用。此外,体外细胞摄取实验显示Gal-ResNPs(37.5μmol/L)增加肝细胞癌(HepG2)细胞对Gal-Res的摄取,并显著抑制细胞的迁移和侵袭。Hoechst33342/丙基碘(PI)双重染色和流式细胞术的实验结果均表明Gal-ResNPs可以显着促进细胞凋亡。此外,Westernblot结果显示Gal-ResNPs显著调节Bcl-2/Bax和AKT/GSK3β/β-catenin信号通路。一起来看,体外/体内结果表明,Gal-ResNP显著提高了Gal-Res的抗肿瘤效率,这是一个潜在的抗肿瘤药物传递系统。
    In our previous studies, 3-O-β-D-galactosylated resveratrol (Gal-Res) was synthesized by structural modification and then 3-O-β-D-galactosylated resveratrol polydopamine nanoparticles (Gal-Res NPs) were successfully prepared to improve the bioavailability and liver distribution of Res. However, the pharmacodynamic efficacy and specific mechanism of Gal-Res NPs on hepatocellular carcinoma remain unclear. Herein, liver cancer model mice were successfully constructed by xenograft tumor modeling. Gal-Res NPs (34.2 mg/kg) significantly inhibited tumor growth of the liver cancer model mice with no significant effect on their body weight and no obvious toxic effect on major organs. Additionally, in vitro cellular uptake assay showed that Gal-Res NPs (37.5 μmol/L) increased the uptake of Gal-Res by Hepatocellular carcinoma (HepG2) cells, and significantly inhibited the cell migration and invasion. The experimental results of Hoechst 33342/propyl iodide (PI) double staining and flow cytometry both revealed that Gal-Res NPs could remarkably promote cell apoptosis. Moreover, the Western blot results revealed that Gal-Res NPs significantly regulated the Bcl-2/Bax and AKT/GSK3β/β-catenin signaling pathways. Taken together, the in vitro/in vivo results demonstrated that Gal-Res NPs significantly improved the antitumor efficiency of Gal-Res, which is a potential antitumor drug delivery system.
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  • 文章类型: Journal Article
    microRNAs(miRNAs)是一类小的非编码RNA,是基因表达的重要调控因子。参与各种生物途径。miRNA的异常表达与结直肠癌(CRC)的发生和发展有关。本研究的目的是探讨5种miRNAs(miR-29a,miR-101,miR-125b,miR-146a,和miR-155),发现在CRC患者的组织样本中失调,临床病理特征和组织学标志物。通过用Ki-67,p53,CD34和Bcl-2对肿瘤组织进行免疫组织化学染色来分析组织学标志物。我们的发现揭示了miR-29a表达与Bcl-2水平之间的显著负相关。此外,miR-29a高表达与CRC患者远处转移发生率较低相关.我们观察到miR-101表达与淋巴结转移数之间的负相关。以及最大转移的大小;miR-125b表达和淋巴管浸润;以及miR-155表达和粘液存在。我们的生存分析表明,高miR-29a表达与CRC患者更好的无进展生存期相关。强调其作为预后标志物的潜力。我们的研究揭示了特定miRNA表达与CRC临床病理特征之间的复杂关系。强调miR-29a作为有价值的预后生物标志物的潜在效用。
    MicroRNAs (miRNAs) are a class of small non-coding RNAs that act as important regulators of gene expression, involved in various biological pathways. Aberrant miRNAs expression is associated with the onset and progression of colorectal cancer (CRC). The aim of this study was to investigate the correlation between five miRNAs (miR-29a, miR-101, miR-125b, miR-146a, and miR-155), found to be deregulated in tissue samples of CRC patients, and clinicopathological characteristics and histological markers. Analysis of histological markers was performed by immunohistochemical staining of tumour tissues with Ki-67, p53, CD34, and Bcl-2. Our findings revealed a significant negative correlation between miR-29a expression and Bcl-2 levels. Furthermore, high miR-29a expression was associated with a lower incidence of distant metastasis in CRC patients. We observed negative correlations between miR-101 expression and the number of lymph nodes with metastasis, as well as the size of the largest metastasis; miR-125b expression and lymphovascular invasion; and miR-155 expression and mucus presence. Our survival analysis demonstrated that high miR-29a expression correlated with better progression-free survival of CRC patients, underscoring its potential as a prognostic marker. Our study unveiled intricate relationships between specific miRNA expressions and clinicopathological features in CRC, highlighting the potential utility of miR-29a as a valuable prognostic biomarker.
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  • 文章类型: Journal Article
    目的:本研究的目的是确定二头肌肌腱(LHBT)长头显微变性与凋亡过程之间的相关性。方法:这项研究包括26例连续的患者,这些患者接受了关节镜下肱二头肌肌腱固定术或肌腱切开术,有或没有肩袖撕裂(RCT)。用苏木精染色后,在光学显微镜下对标本进行组织学检查,伊辛,还有Alcian蓝色.使用原始Bonar评分和修改的Bonar评分评估组织病理学变化,然后与随后的凋亡标志物的表达相关:活化的caspase-3(casp3),肿瘤蛋白p53(p53),B细胞淋巴瘤2(BCL-2)。结果:平均原始Bonar评分为8.65(范围5-11),而改良的Bonar评分为7.61。原始Bonar评分与患者年龄无相关性,但改良Bonar评分与患者年龄呈正相关(p=0.0022).患者年龄与BCL-2和casp3的表达指标无相关性。然而,p53指数的表达与患者年龄呈正相关(p=0.0441)。此外,凋亡指数的表达与原始和改良的Bonar量表之间没有相关性。结论:在LHB肌腱病中,细胞凋亡的表达似乎与变性的程度没有直接关系,特别是在肌腱病的晚期。然而,在胶原蛋白和地面物质中观察到的转化与年龄显着相关,以及根据改良的Bonar评分量化的肌腱组织变性。患者的年龄也与p53指数的表达有关,作为研究人群中细胞凋亡的增加。
    Objectives: The purpose of this study was to determine the correlation between microscopic degeneration in the long head of the biceps tendon (LHBT) and the apoptotic process. Methods: This study included 26 consecutive patients who had undergone arthroscopic biceps tenodesis or tenotomy for symptomatic LHBT with or without concomitant rotator cuff tears (RCTs). Histological examination of the specimens under a light microscope was conducted after staining with hematoxylin, eosin, and the Alcian blue. Histopathological changes were assessed using the original Bonar score and the modified Bonar score and then correlated with the expression of the subsequent apoptosis markers: activated caspase-3 (casp3), tumor protein p53 (p53), and B-cell lymphoma 2 (BCL-2). Results: The mean original Bonar score was 8.65 (range 5-11), while the modified Bonar score was 7.61. There was no correlation between the original Bonar score and the age of the patients, but a positive correlation was found between the modified Bonar score and the age of the patients (p = 0.0022). There was no correlation between the age of patients and the expression indexes of BCL-2 and casp3. However, the expression of the p53 index showed a positive correlation with patient aging (p = 0.0441). Furthermore, there was no correlation observed between the expression of apoptotic indexes and both the original and modified Bonar scale. Conclusions: In LHB tendinopathy, the expression of apoptosis does not seem to directly correlate with the extent of degeneration, particularly in the late stages of tendinopathy. However, the transformations observed in collagen and ground substance were significantly associated with age, as well as tendinous tissue degeneration quantified according to modified Bonar score. The age of patients was also linked with the expression of the p53 index, as an increased apoptosis in the studied population.
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  • 文章类型: Journal Article
    促红细胞生成素(EPO),一种主要由肾脏分泌的激素,通过结合其细胞表面受体(EpoR)发挥其生物学功能。EPO和EpoR在男性和女性生殖系统中的存在已得到验证。因此,EPO的一些关键特性,如它的抗氧化和抗凋亡作用,可以提高精子的受精能力。在本研究中,在37°C下解冻后4小时孵育期间,评估了两种不同浓度的EPO(10mIU/μL和100mIU/μL)对牛精子质量参数的影响。EPO对精子活力有积极作用,生存能力,和总抗氧化能力。此外,EPO抑制细胞凋亡,因为它以剂量依赖性方式降低了BCL2相关的X凋亡调节因子(Bax)/B细胞淋巴瘤2(Bcl-2)的比例和裂解的半胱氨酸-天冬氨酸蛋白酶(caspases)底物水平。此外,EPO诱导精子获能和顶体反应。这些结果为EPO在生殖过程中的生理作用奠定了基础,并有望为进一步研究提供动力,以充分破译EPO在精子生理和生殖中的作用。
    Erythropoietin (EPO), a hormone secreted mainly by the kidney, exerts its biological function by binding to its cell-surface receptor (EpoR). The presence of EPO and EpoR in the male and female reproductive system has been verified. Therefore, some of the key properties of EPO, such as its antioxidant and antiapoptotic effects, could improve the fertilizing capacity of spermatozoa. In the present study, the effect of two different concentrations of EPO (10 mIU/μL and 100 mIU/μL) on bovine sperm-quality parameters was evaluated during a post-thawing 4-h incubation at 37 °C. EPO had a positive effect on sperm motility, viability, and total antioxidant capacity. Moreover, EPO inhibited apoptosis, as it reduced both BCL2-associated X apoptosis regulator (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and cleaved cysteine-aspartic proteases (caspases) substrate levels in a dose-dependent manner. In addition, EPO induced sperm capacitation and acrosome reaction in spermatozoa incubated in capacitation conditioned medeia. These results establish a foundation for the physiological role of EPO in reproductive processes and hopefully will provide an incentive for further research in order to fully decipher the role of EPO in sperm physiology and reproduction.
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  • 文章类型: Journal Article
    Prodiginins(PGs)天然色素是由广谱革兰氏阴性和革兰氏阳性细菌产生的次级代谢产物,特别是沙雷氏菌和链霉菌属中的物种。这些化合物表现出不同和有效的生物活性,包括抗癌,免疫抑制,抗菌,抗疟药,和抗病毒作用。在结构上,PG共享一个共同的三吡咯核心,但具有可变的侧链并经历环化,导致结构多样性。研究已经调查了它们对各种癌细胞系的抗增殖作用,随着一些PG进入癌症治疗的临床试验。这篇综述旨在阐明PG诱导癌细胞凋亡的分子机制,并探索与其抗癌特性相关的结构-活性关系。这些见解可以作为抗癌药物开发进一步研究的基础。可能导致小说的创作,基于PG或其衍生物的靶向治疗。
    The Prodiginins (PGs) natural pigments are secondary metabolites produced by a broad spectrum of gram-negative and gram-positive bacteria, notably by species within the Serratia and Streptomyces genera. These compounds exhibit diverse and potent biological activities, including anticancer, immunosuppressive, antimicrobial, antimalarial, and antiviral effects. Structurally, PGs share a common tripyrrolic core but possess variable side chains and undergo cyclization, resulting in structural diversity. Studies have investigated their antiproliferative effects on various cancer cell lines, with some PGs advancing to clinical trials for cancer treatment. This review aims to illuminate the molecular mechanisms underlying PG-induced apoptosis in cancer cells and explore the structure-activity relationships pertinent to their anticancer properties. Such insights may serve as a foundation for further research in anticancer drug development, potentially leading to the creation of novel, targeted therapies based on PGs or their derivatives.
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  • 文章类型: Journal Article
    提高抗凋亡Bcl-2蛋白的水平是癌细胞摆脱凋亡的重要途径。强调了它们作为抗癌疗法有希望的靶标的重要性。最近,发现与WL-276相比,带有噻唑烷-2,4-二酮的主要化合物1表现出相当的Mcl-1抑制活性。在这里,三十九噻唑烷-2,4-二酮类似物是通过掺入不同的联苯部分(R1),1.氨基酸侧链(R2)和磺酰胺(R3)。结果表明,某些化合物对Bcl-2/Mcl-1表现出有利的抑制作用,同时对Bcl-xL表现出有限或可忽略的结合亲和力。特别是,与AT-101、WL-276和1相比,化合物16和20表现出更大的Bcl-2/Mcl-1抑制。此外,它们在U937细胞中表现出显著的抗增殖作用并显著诱导细胞凋亡。蛋白质印迹和共免疫沉淀测定证实,20可以诱导凋亡相关蛋白表达的改变,从而通过靶向Bcl-2和Mcl-1抑制导致凋亡。此外,20在大鼠血浆和大鼠肝微粒体中均表现出良好的稳定性曲线。总的来说,20可以用作发现具有良好治疗性质的Bcl-2/Mcl-1双重抑制剂的有希望的化合物。
    Increasing the levels of antiapoptotic Bcl-2 proteins is an important way that cancer cells utilize to get out of apoptosis, underscoring their significance as promising targets for anticancer therapies. Lately, a primary compound 1 bearing thiazolidine-2,4-dione was discovered to exhibit comparable Mcl-1 inhibitory activity in comparison to WL-276. Herein, thirty-nine thiazolidine-2,4-dione analogs were yielded through incorporating different biphenyl moieties (R1), amino acid side chains (R2) and sulfonamides (R3) on 1. The findings indicated that certain compounds exhibited favorable inhibitory effects against Bcl-2/Mcl-1, while demonstrating limited or negligible binding affinity towards Bcl-xL. In particular, compounds 16 and 20 exhibited greater Bcl-2/Mcl-1 inhibition compared to AT-101, WL-276 and 1. Moreover, they demonstrated notable antiproliferative effects and significantly induced apoptosis in U937 cells. The western blot and co-immunoprecipitation assays confirmed that 20 could induce alterations in the expression of apoptosis-associated proteins to result in apoptosis through on-target Bcl-2 and Mcl-1 inhibition. In addition, 20 exhibited favorable stability profiles in both rat plasma and rat liver microsomes. In total, 20 could be used as a promising compound to discover Bcl-2/Mcl-1 dual inhibitors with favorable therapeutic properties.
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  • 文章类型: Journal Article
    简介:蜂胶具有广泛的生物和药理作用,包括抗氧化特性-特别是其酚类和类黄酮成分-可以潜在地保护生殖系统免受氧化损伤。方法:随机分为4组,每组40只雄性Wistar大鼠。将载体给予第一组正常对照大鼠阴性对照。第二个,第三,第四组糖尿病大鼠分别口服溶媒(糖尿病对照)和蜂胶,剂量为50和100mg/kg,分别,八个星期。通过注射烟酰胺和链脲佐菌素(STZ)在大鼠中诱发糖尿病。空腹血糖(FBG)和胰岛素水平,胰岛素抵抗的稳态模型评估(HOMA-IR),和精液分析进行评估。此外,血清生殖激素的评估,包括总睾酮(TTST),雌二醇(E2),卵泡刺激素黄体生成素(LH),和催乳素(PRL),在研究结束时测量。组织总睾酮,还评估了E2和二氢睾酮。血清和组织氧化酶,包括过氧化氢酶(CAT),超氧化物歧化酶,和谷胱甘肽过氧化物酶活性,被检查,并测定丙二醛含量。对胰腺和睾丸组织进行组织病理学检查,对睾丸组织中的增殖细胞核抗原(PCNA)和B细胞淋巴瘤2(Bcl-2)进行免疫组织化学分析。使用彗星测定法检查睾丸组织的DNA完整性。结果:与STZ对照组相比,蜂胶能显著降低糖尿病大鼠的FBG水平,改善血糖状态。与STZ-DC组相比,蜂胶增加了雄性大鼠的精子细胞数量和形态正常和存活精子的百分比,提高他们的生育能力。蜂胶也恢复了胰岛,保护睾丸免受氧化应激,血液中生殖激素水平升高,尤其是睾丸激素.此外,高剂量蜂胶对Bcl-2表现出强烈的阳性反应,而生精细胞中增殖细胞核抗原的表达为阴性。结论:获得的数据强烈表明,STZ对睾丸造成严重损害,而蜂胶,作为抗氧化剂,防止STZ对睾丸的不利影响。
    Introduction: Propolis has a wide range of biological and pharmacological actions, including antioxidant properties-particularly its phenolic and flavonoid constituents-that could potentially protect the reproductive system from oxidative damage. Method: Four groups were allocated 40 male Wistar rats each. The vehicle was given to the first group\'s normal control rats negative control. The second, third, and fourth groups of diabetic rats were given vehicle (diabetic control) and propolis orally at 50 and 100 mg/kg, respectively, for 8 weeks. Diabetes was induced in rats via injection of nicotinamide and streptozotocin (STZ). Fasting blood glucose (FBG) and insulin levels, homeostatic model assessment for insulin resistance (HOMA-IR), and semen analysis were assessed. In addition, assessments of serum reproductive hormones, including total testosterone (TTST), estradiol (E2), follicle-stimulating hormone luteinizing hormone (LH), and prolactin (PRL), were measured at the end of the study. Tissue total testosterone, E2, and dihydrotestosterone were also evaluated. Serum and tissue oxidative enzymes, including catalase (CAT), superoxide dismutase, and glutathione peroxidase activities, were examined, and malondialdehyde content was determined. The pancreatic and testicular tissues were histopathologically examined, and proliferating cell nuclear antigen (PCNA) and B-cell lymphoma 2 (Bcl-2) in testicular tissue were immunohistochemically analyzed. Testicular tissue was examined for DNA integrity using a comet assay. Results: Compared to the STZ-control group, propolis greatly decreased FBG levels and improved the glycemic status of diabetic rats. In comparison to the STZ-DC group, propolis increased the number of sperm cells and the percent of morphologically normal and viable sperm in male rats, improving their fertility. Propolis also restored the pancreatic islets, protected the testis from oxidative stress, and increased levels of reproductive hormones in the blood, especially testosterone. Moreover, propolis at high doses demonstrated a strong positive response for Bcl-2 and a negative expression of proliferating cell nuclear antigen in spermatogenic cells. Conclusion: The data obtained strongly indicate that STZ causes severe impairments to the testis whereas propolis, acting as an antioxidant, protects against the adverse effects of STZ on the testis.
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  • 文章类型: Journal Article
    Bcl-2家族通过促凋亡蛋白和抗凋亡蛋白的直接相互作用来控制凋亡。主要机制是促凋亡蛋白的BH3结构域与抗凋亡同胞的疏水沟结合,已被批准的BH3模拟抗癌药物在治疗上利用。证据表明,Bcl-2蛋白的跨膜结构域(TMD)也可以介导Bcl-2相互作用。我们开发了一种高度特异性的分裂荧光素酶测定法,能够分析成孔凋亡效应子BAX的TMD相互作用,BAK,和BOK在活细胞中具有抗凋亡Bcl-2蛋白。我们证实了BAX-TMD的同型相互作用,而且新发现抗凋亡BCL-2的TMD与BOK的TMD的相互作用,一种特殊的促凋亡Bcl-2蛋白。BOK-TMD和BCL-2-TMD在内质网相互作用。分子动力学模拟证实了动态BOK-TMD和BCL-2-TMD二聚体和稳定的异四聚体。BCL-2-TMD在预测的关键残基处的突变消除了与BOK-TMD的相互作用。此外,BCL-2对BOK诱导的凋亡的抑制特别取决于它们的TMD。因此,Bcl-2蛋白的TMD是凋亡调控的相关相互作用界面,并提供了新的潜在药物靶标。
    The Bcl-2 family controls apoptosis by direct interactions of pro- and anti-apoptotic proteins. The principle mechanism is binding of the BH3 domain of pro-apoptotic proteins to the hydrophobic groove of anti-apoptotic siblings, which is therapeutically exploited by approved BH3-mimetic anti-cancer drugs. Evidence suggests that also the transmembrane domain (TMD) of Bcl-2 proteins can mediate Bcl-2 interactions. We developed a highly-specific split luciferase assay enabling the analysis of TMD interactions of pore-forming apoptosis effectors BAX, BAK, and BOK with anti-apoptotic Bcl-2 proteins in living cells. We confirm homotypic interaction of the BAX-TMD, but also newly identify interaction of the TMD of anti-apoptotic BCL-2 with the TMD of BOK, a peculiar pro-apoptotic Bcl-2 protein. BOK-TMD and BCL-2-TMD interact at the endoplasmic reticulum. Molecular dynamics simulations confirm dynamic BOK-TMD and BCL-2-TMD dimers and stable heterotetramers. Mutation of BCL-2-TMD at predicted key residues abolishes interaction with BOK-TMD. Also, inhibition of BOK-induced apoptosis by BCL-2 depends specifically on their TMDs. Thus, TMDs of Bcl-2 proteins are a relevant interaction interface for apoptosis regulation and provide a novel potential drug target.
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  • 文章类型: Journal Article
    丙酮酸激酶M2(PKM2)是与肌醇1,4,5-三磷酸受体(IP3R)相互作用的关键糖酵解酶。这种相互作用抑制了IP3R介导的胞浆[Ca2]的上升。由于PKM2以单体形式存在,显示不同性质的二聚体和四聚体形式,包括催化活性,我们研究了PKM2与IP3Rs相互作用的分子决定簇。用TEPP-46(一种稳定PKM2四聚体形式的化合物)处理HeLa细胞增加了其催化活性和对IP3R介导的Ca2+信号的抑制。始终如一,在PKM2敲除HeLa细胞中,PKM2C424L,四聚体,高活性PKM2突变体,但不是不活跃的PKM2K270M或不活跃的PKM2K305Q,抑制IP3R介导的Ca2+释放。令人惊讶的是,然而,体外测定没有揭示纯化的PKM2与IP3R1的纯化片段5(a.a.1932-2216)或其中定位的D5SD肽(a.a.2078-2098的IP3R1)之间的直接相互作用,IP3R上PKM2的假定相互作用位点。此外,在缺乏内源性IP3R的DT40细胞中异源表达IP3R1的核上膜片钳未显示纯化的野生型PKM2,突变型PKM2或PKM1蛋白的任何功能作用。这些结果表明,其他因子介导了纤维素中PKM2对IP3R的调节。使用HeLa细胞裂解物共沉淀IP3R1、IP3R3和PKM2的GRP75的免疫沉淀。此外,D5SD肽不仅破坏了PKM2:IP3R,还有PKM2:GRP75和GRP75:IP3R相互作用。因此,我们的数据支持一种具有催化活性的模型,四聚体PKM2通过涉及GRP75的多蛋白复合物通过IP3R抑制Ca2信号传导。
    Pyruvate kinase M2 (PKM2) is a key glycolytic enzyme interacting with the inositol 1,4,5-trisphosphate receptor (IP3R). This interaction suppresses IP3R-mediated cytosolic [Ca2+] rises. As PKM2 exists in monomeric, dimeric and tetrameric forms displaying different properties including catalytic activity, we investigated the molecular determinants of PKM2 enabling its interaction with IP3Rs. Treatment of HeLa cells with TEPP-46, a compound stabilizing the tetrameric form of PKM2, increased both its catalytic activity and the suppression of IP3R-mediated Ca2+ signals. Consistently, in PKM2 knock-out HeLa cells, PKM2C424L, a tetrameric, highly active PKM2 mutant, but not inactive PKM2K270M or the less active PKM2K305Q, suppressed IP3R-mediated Ca2+ release. Surprisingly, however, in vitro assays did not reveal a direct interaction between purified PKM2 and either the purified Fragment 5 of IP3R1 (a.a. 1932-2216) or the therein located D5SD peptide (a.a. 2078-2098 of IP3R1), the presumed interaction sites of PKM2 on the IP3R. Moreover, on-nucleus patch clamp of heterologously expressed IP3R1 in DT40 cells devoid of endogenous IP3Rs did not reveal any functional effect of purified wild-type PKM2, mutant PKM2 or PKM1 proteins. These results indicate that an additional factor mediates the regulation of the IP3R by PKM2 in cellulo. Immunoprecipitation of GRP75 using HeLa cell lysates co-precipitated IP3R1, IP3R3 and PKM2. Moreover, the D5SD peptide not only disrupted PKM2:IP3R, but also PKM2:GRP75 and GRP75:IP3R interactions. Our data therefore support a model in which catalytically active, tetrameric PKM2 suppresses Ca2+ signaling via the IP3R through a multiprotein complex involving GRP75.
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