Adenylyl Cyclases

腺苷酸环化酶
  • 文章类型: Journal Article
    腺苷酸环化酶(AC)的异源致敏导致cAMP信号转导升高,从而导致药物依赖。通过阻断cullin3的neddylation抑制cullin3-RING连接酶可以消除异源敏化,然而,调节机制仍然未知。这里,我们报道了钾通道四聚化结构域(KCTD)蛋白2,5和17,尤其是显性同工型KCTD5通过与cullin3和cullin相关和neddylation解离1(CAND1)蛋白的作用,在调节AC1和吗啡依赖的异源致敏中的重要作用.在细胞模型中,我们观察到KCTD5与Gβ和cullin3的增强关联,以及在AC1的异源致敏中Gβ与cullin3的解离升高。鉴于CAND1的结合抑制了cullin3的neddylation,我们进一步阐明了KCTD5与Gβ和cullin3的增强相互作用促进了CAND1与cullin3的解离,减弱了CAND1对cullin3neddylation的抑制作用,最终导致AC1的异源致敏。脑室旁丘脑核(PVT)在介导吗啡依赖中起重要作用。通过药理学和生物化学方法,然后我们证明KCTD5/cullin3通过调节AC的异源致敏调节吗啡依赖,可能AC1在小鼠PVT中。总之,本研究揭示了cullin3介导的AC1异源致敏的潜在机制,并发现了KCTD蛋白在调节小鼠吗啡依赖中的作用。
    Heterologous sensitization of adenylyl cyclase (AC) results in elevated cAMP signaling transduction that contributes to drug dependence. Inhibiting cullin3-RING ligases by blocking the neddylation of cullin3 abolishes heterologous sensitization, however, the modulating mechanism remains uncharted. Here, we report an essential role of the potassium channel tetramerization domain (KCTD) protein 2, 5, and 17, especially the dominant isoform KCTD5 in regulating heterologous sensitization of AC1 and morphine dependence via working with cullin3 and the cullin-associated and neddylation-dissociated 1 (CAND1) protein. In cellular models, we observed enhanced association of KCTD5 with Gβ and cullin3, along with elevated dissociation of Gβ from AC1 as well as of CAND1 from cullin3 in heterologous sensitization of AC1. Given binding of CAND1 inhibits the neddylation of cullin3, we further elucidated that the enhanced interaction of KCTD5 with both Gβ and cullin3 promoted the dissociation of CAND1 from cullin3, attenuated the inhibitory effect of CAND1 on cullin3 neddylation, ultimately resulted in heterologous sensitization of AC1. The paraventricular thalamic nucleus (PVT) plays an important role in mediating morphine dependence. Through pharmacological and biochemical approaches, we then demonstrated that KCTD5/cullin3 regulates morphine dependence via modulating heterologous sensitization of AC, likely AC1 in PVT in mice. In summary, the present study revealed the underlying mechanism of heterologous sensitization of AC1 mediated by cullin3 and discovered the role of KCTD proteins in regulating morphine dependence in mice.
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  • 文章类型: Journal Article
    肥厚型心肌病(HCM)起因于负责编码心肌相关蛋白的基因中的致病变体。Forskolin(FSK),从鞘氨醇单胞菌中分离出的拉布丹二萜,表现出不同的药理作用,包括支气管痉挛缓解,眼内压降低,和青光眼治疗。然而,FSK是否能调节HCM及其相关机制尚不清楚.这里,我们发现FSK可以减轻两种HCM小鼠模型(Myh6R404Q和Tnnt2R109Q)的体内心肌肥厚。此外,FSK可以防止去甲肾上腺素(NE)诱导的心肌细胞肥大。它逆转了心功能不全,缩小扩大的细胞大小,并下调肥大相关基因的表达。我们进一步证明了FSK减轻HCM的机制依赖于ADCY6的激活。总之,我们的研究结果表明,FSK通过调节ADCY6/cAMP/PKA通路减轻肥厚型心肌病,这表明FSK有望成为HCM的治疗剂。
    Hypertrophic cardiomyopathy (HCM) arises from a pathogenic variant in the gene responsible for encoding the myocardium-associated protein. Forskolin (FSK), a labdane diterpene isolated from Sphingomonas capillaris, exhibits diverse pharmacological effects, including bronchospasm relief, intraocular pressure reduction, and glaucoma treatment. However, whether FSK could regulate HCM and its associated mechanism remains unclear. Here, we discovered that FSK could mitigate cardiac hypertrophy in two HCM mouse models (Myh6R404Q and Tnnt2R109Q) in vivo. Additionally, FSK could prevent norepinephrine (NE)-induced cardiomyocyte hypertrophy in vitro. It reversed cardiac dysfunction, reduced enlarged cell size, and downregulated the expression of hypertrophy-related genes. We further demonstrated that FSK\'s mechanism in alleviating HCM relied on the activation of ADCY6. In conclusion, our findings demonstrate that FSK alleviates hypertrophic cardiomyopathy by modulating the ADCY6/cAMP/PKA pathway, suggesting that FSK holds promise as a therapeutic agent for HCM.
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  • 文章类型: Journal Article
    疼痛和焦虑是帕金森病(PD)中两种常见且治疗不足的非运动症状,影响PD患者的生活质量,和潜在的机制仍然不清楚。作为腺苷酸环化酶(ACs)的重要亚型,腺苷酸环化酶亚型1(AC1)对于诱导皮层长时程增强(LTP)和损伤诱导的突触增强至关重要,包括前扣带回皮层(ACC)和岛叶皮层(IC)。在不同的动物模型中,AC1的遗传缺失或AC1的药理学抑制改善了慢性疼痛和焦虑。在这项研究中,我们证明了运动缺陷,疼痛,1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)处理的小鼠模型中PD的焦虑症状。作为主要候选AC1抑制剂,口服(1剂和7剂)NB001(20和40mg/kg)在MPTP治疗的小鼠中显示出显着的镇痛作用,焦虑行为也减少(40mg/kg)。通过使用基因敲除小鼠,我们发现AC1敲除小鼠在MPTP给药后疼痛和焦虑症状减轻,但不是AC8基因敲除小鼠。总之,AC1的遗传缺失或AC1的药物抑制改善PD模型小鼠的疼痛和焦虑症状,但没有影响运动功能。这些结果表明,NB001是通过抑制AC1靶点治疗PD患者疼痛和焦虑症状的潜在药物。
    Pain and anxiety are two common and undertreated non-motor symptoms in Parkinson\'s disease (PD), which affect the life quality of PD patients, and the underlying mechanisms remain unclear. As an important subtype of adenylyl cyclases (ACs), adenylyl cyclase subtype 1 (AC1) is critical for the induction of cortical long-term potentiation (LTP) and injury induced synaptic potentiation in the cortical areas including anterior cingulate cortex (ACC) and insular cortex (IC). Genetic deletion of AC1 or pharmacological inhibition of AC1 improved chronic pain and anxiety in different animal models. In this study, we proved the motor deficit, pain and anxiety symptoms of PD in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice model. As a lead candidate AC1 inhibitor, oral administration (1 dose and seven doses) of NB001 (20 and 40 mg/kg) showed significant analgesic effect in MPTP-treated mice, and the anxiety behavior was also reduced (40 mg/kg). By using genetic knockout mice, we found that AC1 knockout mice showed reduced pain and anxiety symptoms after MPTP administration, but not AC8 knockout mice. In summary, genetic deletion of AC1 or pharmacological inhibition of AC1 improved pain and anxiety symptoms in PD model mice, but didn\'t affect motor function. These results suggest that NB001 is a potential drug for the treatment of pain and anxiety symptoms in PD patients by inhibiting AC1 target.
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  • 文章类型: Journal Article
    突触可塑性是学习的关键细胞模型,记忆和慢性疼痛。以前的大多数研究都是在大鼠和小鼠中进行的,对非人灵长类动物的突触可塑性知之甚少。在本研究中,我们使用综合实验方法研究了成年树sh的前扣带回皮质(ACC)的长期增强(LTP)。我们发现谷氨酸是主要的兴奋性递质,α-氨基-3-羟基-5-甲基-4-异恶唑-丙酸(AMPA)受体介导突触后反应。树sh的LTP大于成年小鼠,持续至少5小时。N-甲基-d-天冬氨酸(NMDA)受体,Ca2内流和腺苷酸环化酶1(AC1)有助于树theLTP。我们的结果表明,LTP是灵长类动物ACC中突触可塑性的主要形式。本文是讨论会议问题“长期增强:50年后”的一部分。
    Synaptic plasticity is a key cellular model for learning, memory and chronic pain. Most previous studies were carried out in rats and mice, and less is known about synaptic plasticity in non-human primates. In the present study, we used integrative experimental approaches to study long-term potentiation (LTP) in the anterior cingulate cortex (ACC) of adult tree shrews. We found that glutamate is the major excitatory transmitter and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionicacid (AMPA) receptors mediate postsynaptic responses. LTP in tree shrews was greater than that in adult mice and lasted for at least 5 h. N-methyl-d-aspartic acid (NMDA) receptors, Ca2+ influx and adenylyl cyclase 1 (AC1) contributed to tree shrew LTP. Our results suggest that LTP is a major form of synaptic plasticity in the ACC of primate-like animals. This article is part of a discussion meeting issue \'Long-term potentiation: 50 years on\'.
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  • 文章类型: Journal Article
    曲霉是一种传统的产生曲霉毒素A(OTA)的真菌,具有密度依赖的行为,这被称为群体感应(QS),由信号分子介导。单个细胞通过通讯来适应环境变化的趋势,让真菌占据重要的生态位。信号感知,传输,和反馈都依赖于由膜受体和细胞内效应子构成的信号网络。然而,密度信息在信号转导中的干扰,调节曲霉的大部分生命活动,尚未阐明。在这里,我们表明,G蛋白偶联受体(GPCR)cAMP途径负责传递密度信息,并调节了A.ochracus生命周期的关键点。首先,确认了A.ochracus的群体感应现象,并确定密度阈值为103孢子/mL,这表示在一系列法定密度中产生最多OTA的低密度。此外,被归类为糖传感器的GprC,以及响应于配体葡萄糖和HODE的细胞内腺苷酸环化酶(AcyA)-cAMP-PKA途径被证实。此外,GprC和AcyA调节初级代谢和次级代谢,并进一步影响A.ochracus在整个生命周期中的生长。这些研究强调了由碳水化合物和氧化脂素介导的细胞通讯的关键G蛋白信号通路,并阐明了真菌发育的综合作用,其中包括直接的基因调控和间接的底物或能量供应。我们的工作揭示了更多的信号分子,这些信号分子介导了密度信息,并对曲霉的重要适应行为产生了关联效应,希望通过阻断细胞通讯实现对霉菌毒素污染的综合防治。
    Aspergillus ochraceus is the traditional ochratoxin A (OTA)-producing fungus with density-dependent behaviors, which is known as quorum sensing (QS) that is mediated by signaling molecules. Individual cells trend to adapt environmental changes in a \"whole\" flora through communications, allowing fungus to occupy an important ecological niche. Signals perception, transmission, and feedback are all rely on a signal network that constituted by membrane receptors and intracellular effectors. However, the interference of density information in signal transduction, which regulates most life activities of Aspergillus, have yet to be elucidated. Here we show that the G protein-coupled receptor (GPCR) to cAMP pathway is responsible for transmitting density information, and regulates the key point in life cycle of A. ochraceus. Firstly, the quorum sensing phenomenon of A. ochraceus is confirmed, and identified the density threshold is 103 spores/mL, which represents the low density that produces the most OTA in a series quorum density. Moreover, the GprC that classified as sugar sensor, and intracellular adenylate cyclase (AcyA)-cAMP-PKA pathway that in response to ligands glucose and HODEs are verified. Furthermore, GprC and AcyA regulate the primary metabolism as well as secondary metabolism, and further affects the growth of A. ochraceus during the entire life cycle. These studies highlight a crucial G protein signaling pathway for cell communication that is mediated by carbohydrate and oxylipins, and clarified a comprehensive effect of fungal development, which include the direct gene regulation and indirect substrate or energy supply. Our work revealed more signal molecules that mediated density information and connected effects on important adaptive behaviors of Aspergillus ochraceus, hoping to achieve comprehensive prevention and control of mycotoxin pollution from interrupting cell communication.
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  • 文章类型: Journal Article
    纹状体在指导从运动控制到动作选择和奖励学习的许多复杂行为中起着核心作用。在我们的研究中,我们使用了55只具有快速衰变连锁不平衡的CFW小鼠,通过分析其纹状体转录组和79个测量的行为表型数据,系统地挖掘了纹状体相关的行为功能基因。通过构建基因共表达网络,我们把基因分成13个模块,其中大多数与运动性状呈正相关。基于功能注释以及Fisher的精确和超几何分布检验,棕色和洋红色模块被确定为核心模块。它们显着富集了纹状体相关的功能基因。随后的孟德尔随机化分析验证了核心模块与运动障碍之间的因果关系。通过模块内基因连接分析,Adcy5和Kcnma1被鉴定为棕色和洋红色模块集线器基因,分别。基因敲除Adcy5和Kcnma1导致小鼠运动功能障碍,KCNMA1是人类精神分裂症和吸烟成瘾的风险基因。我们还评估了每个模块的细胞组成,并确定了纹状体中的少突胶质细胞在运动调节中具有积极作用。意义声明纹状体在指导从运动控制到动作选择和奖励学习的许多复杂行为中起着核心作用。临床上,纹状体功能障碍导致多种神经退行性疾病,包括众所周知的阿尔茨海默病和亨廷顿病。在我们的研究中,我们使用55只CFW小鼠系统地挖掘了纹状体相关的行为功能基因。我们以多种方式验证了我们的发现。我们发现小鼠中的Adcy5和Kcnma1敲除导致小鼠运动功能障碍,并且Kcnma1与精神分裂症有关,这个发现对人类来说是正确的。最后,我们还评估了不同细胞在纹状体行为调节中的作用,发现纹状体中的少突胶质细胞在运动调节中起着积极的作用。
    The striatum plays a central role in directing many complex behaviors ranging from motor control to action choice and reward learning. In our study, we used 55 male CFW mice with rapid decay linkage disequilibrium to systematically mine the striatum-related behavioral functional genes by analyzing their striatal transcriptomes and 79 measured behavioral phenotypic data. By constructing a gene coexpression network, we clustered the genes into 13 modules, with most of them being positively correlated with motor traits. Based on functional annotations as well as Fisher\'s exact and hypergeometric distribution tests, brown and magenta modules were identified as core modules. They were significantly enriched for striatal-related functional genes. Subsequent Mendelian randomization analysis verified the causal relationship between the core modules and dyskinesia. Through the intramodular gene connectivity analysis, Adcy5 and Kcnma1 were identified as brown and magenta module hub genes, respectively. Knock outs of both Adcy5 and Kcnma1 lead to motor dysfunction in mice, and KCNMA1 acts as a risk gene for schizophrenia and smoking addiction in humans. We also evaluated the cellular composition of each module and identified oligodendrocytes in the striatum to have a positive role in motor regulation.
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  • 文章类型: Journal Article
    背景:最近的动物和临床研究结果一致强调了降钙素基因相关肽(CGRP)在慢性偏头痛(CM)和相关情绪反应中的关键作用。CGRP抗体和受体拮抗剂已被批准用于CM治疗。然而,疼痛相关皮质中潜在的CGRP相关信号通路仍知之甚少.
    方法:SD大鼠采用硬膜灌注炎性汤建立CM模型。使用von-Frey细丝评估眶周机械阈值,通过开阔视野和高架迷宫测试观察到焦虑样行为。c-Fos的表达,使用免疫荧光和蛋白质印迹分析检测CGRP和NMDAGluN2B受体。通过全细胞膜片钳记录检测兴奋性突触传递。人类使用的腺苷酸环化酶1(AC1)抑制剂,通过脑岛立体定位和腹膜内注射在CM大鼠中应用hNB001。
    结果:偏头痛模型大鼠的岛叶皮层(IC)被激活。谷氨酸介导的兴奋性传递和IC中的NMDAGluN2B受体增强。在伤害性和焦虑样活动期间,IC中的CGRP水平显着增加。在IC中局部应用hNB001或腹膜内减轻偏头痛大鼠的眶周机械阈值和焦虑行为。此外,CGRP在IC中表达下降后应用hNB001。
    结论:我们的研究表明AC1依赖性IC可塑性有助于偏头痛,AC1可能是未来治疗偏头痛的一个有希望的靶点。
    BACKGROUND: Recent animal and clinical findings consistently highlight the critical role of calcitonin gene-related peptide (CGRP) in chronic migraine (CM) and related emotional responses. CGRP antibodies and receptor antagonists have been approved for CM treatment. However, the underlying CGRP-related signaling pathways in the pain-related cortex remain poorly understood.
    METHODS: The SD rats were used to establish the CM model by dural infusions of inflammatory soup. Periorbital mechanical thresholds were assessed using von-Frey filaments, and anxiety-like behaviors were observed via open field and elevated plus maze tests. Expression of c-Fos, CGRP and NMDA GluN2B receptors was detected using immunofluorescence and western blotting analyses. The excitatory synaptic transmission was detected by whole-cell patch-clamp recording. A human-used adenylate cyclase 1 (AC1) inhibitor, hNB001, was applied via insula stereotaxic and intraperitoneal injections in CM rats.
    RESULTS: The insular cortex (IC) was activated in the migraine model rats. Glutamate-mediated excitatory transmission and NMDA GluN2B receptors in the IC were potentiated. CGRP levels in the IC significantly increased during nociceptive and anxiety-like activities. Locally applied hNB001 in the IC or intraperitoneally alleviated periorbital mechanical thresholds and anxiety behaviors in migraine rats. Furthermore, CGRP expression in the IC decreased after the hNB001 application.
    CONCLUSIONS: Our study indicated that AC1-dependent IC plasticity contributes to migraine and AC1 may be a promising target for treating migraine in the future.
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  • 文章类型: Journal Article
    最近使用不同实验方法的研究表明,包括感觉皮层和前扣带皮层(ACC)在内的成年皮层中可能存在无声突触。ACC中的长期增强(LTP)的突触后形式募集了这些沉默的突触中的一些突触,并且这种募集需要钙刺激的腺苷酸环化酶(AC)的活性。尚不清楚AC的化学激活是否可以招募沉默的突触。在这项研究中,我们发现ACs的激活有助于成年小鼠ACC的突触增强。Forskolin,ACs的选择性激活剂,成年小鼠ACC中招募的沉默反应。招聘是长期的。有趣的是,毛喉素的作用并不普遍,一些沉默的突触没有经历增强或募集。这些发现表明,这些成人皮质突触不是同质的。选择性钙通透性AMPA受体抑制剂1-萘基乙酰精胺(NASPM)的应用逆转了沉默反应的增强和募集,表明AMPA受体是必需的。我们的结果强烈表明,AC依赖性突触后AMPA受体有助于皮质LTP上沉默反应的募集。
    Recent studies using different experimental approaches demonstrate that silent synapses may exist in the adult cortex including the sensory cortex and anterior cingulate cortex (ACC). The postsynaptic form of long-term potentiation (LTP) in the ACC recruits some of these silent synapses and the activity of calcium-stimulated adenylyl cyclases (ACs) is required for such recruitment. It is unknown if the chemical activation of ACs may recruit silent synapses. In this study, we found that activation of ACs contributed to synaptic potentiation in the ACC of adult mice. Forskolin, a selective activator of ACs, recruited silent responses in the ACC of adult mice. The recruitment was long-lasting. Interestingly, the effect of forskolin was not universal, some silent synapses did not undergo potentiation or recruitment. These findings suggest that these adult cortical synapses are not homogenous. The application of a selective calcium-permeable AMPA receptor inhibitor 1-naphthyl acetyl spermine (NASPM) reversed the potentiation and the recruitment of silent responses, indicating that the AMPA receptor is required. Our results strongly suggest that the AC-dependent postsynaptic AMPA receptor contributes to the recruitment of silent responses at cortical LTP.
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  • 文章类型: Journal Article
    射血分数保留的心力衰竭(HFpEF)是心力衰竭(HF)的主要亚型之一,迄今为止尚无有效的治疗方法。心脏纤维化是HF病理学的核心,也是治疗HFpEF的潜在途径。探讨HFpEF病理生理过程中与纤维化相关的关键基因和通路,构建HFpEF小鼠模型。从基因表达综合数据库下载相关基因表达谱,针对纤维化相关通路进行单样本基因集富集分析(ssGSEA),通过对纤维化相关基因的交叉制表分析,探索健康对照和HFpEF心脏组织中的差异表达基因(DEGs)。对鉴定的纤维化相关基因进行基因本体论(GO)富集和京都基因和基因组百科全书(KEGG)途径富集分析。选择了两个最重要的DEG,并在HFpEF小鼠中进行进一步验证。结果表明,与健康对照组相比,HFpEF小鼠的心肌纤维化显著上调,而ssGSEA结果显示HFpEF心肌组织中9条纤维化相关通路的富集存在显著差异,798个DEG中有112个与纤维化有关。体内实验结果表明,HFpEF小鼠心脏组织中抵抗素样分子γ(Relmg)和腺苷酸环化酶1(Adcy1)的表达水平显著升高和降低,分别,与健康对照相比。一起来看,这些结果表明,Relmg和Acdy1以及纤维化过程可能是HFpEF治疗的潜在靶点.
    Heart failure with preserved ejection fraction (HFpEF) is one of the major subtypes of heart failure (HF) and no effective treatments for this common disease exist to date. Cardiac fibrosis is central to the pathology of HF and a potential avenue for the treatment of HFpEF. To explore key fibrosis-related genes and pathways in the pathophysiological process of HFpEF, a mouse model of HFpEF was constructed. The relevant gene expression profiles were downloaded from the Gene Expression Omnibus database, and single-sample Gene Set Enrichment Analysis (ssGSEA) was performed targeting fibrosis-related pathways to explore differentially expressed genes (DEGs) in healthy control and HFpEF heart tissues with cross-tabulation analysis of fibrosis-related genes. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the identified fibrosis-related genes. The two most significant DEGs were selected, and further validation was conducted in HFpEF mice. The results indicated that myocardial fibrosis was significantly upregulated in HFpEF mice compared to healthy controls, while the ssGSEA results revealed significant differences in the enrichment of nine fibrosis-related pathways in HFpEF myocardial tissue, with 112 out of 798 DEGs being related to fibrosis. The in vivo results demonstrated that expression levels of resistin-like molecule gamma (Relmg) and adenylate cyclase 1 (Adcy1) in the heart tissues of HFpEF mice were significantly higher and lower, respectively, compared to healthy controls. Taken together, these results suggest that Relmg and Acdy1 as well as the fibrosis process may be potential targets for HFpEF treatment.
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  • 文章类型: Journal Article
    几十年来,通过G蛋白偶联受体(GPCRs)的信号转导一直是细胞生物学的主要焦点。许多病症与利用Gi蛋白抑制腺苷酸环化酶(AC)以及调节其他效应物的GPCR相关。一些早期研究通过测量组成型活性Gαi突变体的推定区域的同源替换后的活性丧失,成功地定义了Gαi几个成员的AC相互作用域。然而,这些发现是否确实可以转化为受体激活的Gαi的背景尚未得到严格验证.为了解决这个问题,我们在Gαi1的GTP酶缺陷型Q204L(QL)和R178C(RC)突变体中引入了一系列已知和新的嵌合突变,然后对其抑制AC的能力进行了检查.令人惊讶的是,大多数嵌合体未能消除QL突变带来的组成活性,而一些能够消除RC突变体的抑制活性。在携带百日咳毒素(PTX)抗性C351I突变的相同嵌合构建体中类似地观察到受体介导的AC抑制。此外,带有RC的功能丧失嵌合体似乎被内源性RGS蛋白过度失活。分子对接揭示了AC与Gαi1的α3/β5环之间的潜在相互作用。随后的cAMP测定支持α3/β5环的协同作用,α4螺旋,和α4/β6环介导Gαi1-i3对AC的抑制。我们的结果揭示了组成型活性突变体和受体激活的Gαi1之间抑制AC的显着功能差异,并确定了以前未知的Gαi亚基的AC相互作用域。这些结果共同为细胞环境中AC抑制的机制提供了有价值的见解。
    Signal transduction through G protein-coupled receptors (GPCRs) has been a major focus in cell biology for decades. Numerous disorders are associated with GPCRs that utilize Gi proteins to inhibit adenylyl cyclase (AC) as well as regulate other effectors. Several early studies have successfully defined the AC-interacting domains of several members of Gαi by measuring the loss of activity upon homologous replacements of putative regions of constitutive active Gαi mutants. However, whether such findings can indeed be translated into the context of a receptor-activated Gαi have not been rigorously verified. To address this issue, an array of known and new chimeric mutations was introduced into GTPase-deficient Q204L (QL) and R178C (RC) mutants of Gαi1, followed by examinations on their ability to inhibit AC. Surprisingly, most chimeras failed to abolish the constitutive activity brought on by the QL mutation, while some were able to eliminate the inhibitory activity of RC mutants. Receptor-mediated inhibition of AC was similarly observed in the same chimeric constructs harbouring the pertussis toxin (PTX)-resistant C351I mutation. Moreover, RC-bearing loss-of-function chimeras appeared to be hyper-deactivated by endogenous RGS protein. Molecular docking revealed a potential interaction between AC and the α3/β5 loop of Gαi1. Subsequent cAMP assays support a cooperative action of the α3/β5 loop, the α4 helix, and the α4/β6 loop in mediating AC inhibition by Gαi1-i3. Our results unveiled a notable functional divergence between constitutively active mutants and receptor-activated Gαi1 to inhibit AC, and identified a previously unknown AC-interacting domain of Gαi subunits. These results collectively provide valuable insights on the mechanism of AC inhibition in the cellular environment.
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