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1.
The evolutionarily conserved serine-threonine kinase mammalian target of rapamycin (mTOR) plays a critical role in regulating many pathophysiological processes. Functional characterization of the mTOR signaling pathways, however, has been hampered by the paucity of known substrates. We used large-scale quantitative phosphoproteomics experiments to define the signaling networks downstream of mTORC1 and mTORC2. Characterization of one mTORC1 substrate, the growth factor receptor-bound protein 10 (Grb10), showed that mTORC1-mediated phosphorylation stabilized Grb10, leading to feedback inhibition of the phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated, mitogen-activated protein kinase (ERK-MAPK) pathways. Grb10 expression is frequently down-regulated in various cancers, and loss of Grb10 and loss of the well-established tumor suppressor phosphatase PTEN appear to be mutually exclusive events, suggesting that Grb10 might be a tumor suppressor regulated by mTORC1.  相似文献   

2.
The mTOR complex 1 (mTORC1) protein kinase is a master growth regulator that is stimulated by amino acids. Amino acids activate the Rag guanosine triphosphatases (GTPases), which promote the translocation of mTORC1 to the lysosomal surface, the site of mTORC1 activation. We found that the vacuolar H(+)-adenosine triphosphatase ATPase (v-ATPase) is necessary for amino acids to activate mTORC1. The v-ATPase engages in extensive amino acid-sensitive interactions with the Ragulator, a scaffolding complex that anchors the Rag GTPases to the lysosome. In a cell-free system, ATP hydrolysis by the v-ATPase was necessary for amino acids to regulate the v-ATPase-Ragulator interaction and promote mTORC1 translocation. Results obtained in vitro and in human cells suggest that amino acid signaling begins within the lysosomal lumen. These results identify the v-ATPase as a component of the mTOR pathway and delineate a lysosome-associated machinery for amino acid sensing.  相似文献   

3.
The Rag GTPases bind raptor and mediate amino acid signaling to mTORC1   总被引:3,自引:0,他引:3  
The multiprotein mTORC1 protein kinase complex is the central component of a pathway that promotes growth in response to insulin, energy levels, and amino acids and is deregulated in common cancers. We find that the Rag proteins--a family of four related small guanosine triphosphatases (GTPases)--interact with mTORC1 in an amino acid-sensitive manner and are necessary for the activation of the mTORC1 pathway by amino acids. A Rag mutant that is constitutively bound to guanosine triphosphate interacted strongly with mTORC1, and its expression within cells made the mTORC1 pathway resistant to amino acid deprivation. Conversely, expression of a guanosine diphosphate-bound Rag mutant prevented stimulation of mTORC1 by amino acids. The Rag proteins do not directly stimulate the kinase activity of mTORC1, but, like amino acids, promote the intracellular localization of mTOR to a compartment that also contains its activator Rheb.  相似文献   

4.
Rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1), extends the life spans of yeast, flies, and mice. Calorie restriction, which increases life span and insulin sensitivity, is proposed to function by inhibition of mTORC1, yet paradoxically, chronic administration of rapamycin substantially impairs glucose tolerance and insulin action. We demonstrate that rapamycin disrupted a second mTOR complex, mTORC2, in vivo and that mTORC2 was required for the insulin-mediated suppression of hepatic gluconeogenesis. Further, decreased mTORC1 signaling was sufficient to extend life span independently from changes in glucose homeostasis, as female mice heterozygous for both mTOR and mLST8 exhibited decreased mTORC1 activity and extended life span but had normal glucose tolerance and insulin sensitivity. Thus, mTORC2 disruption is an important mediator of the effects of rapamycin in vivo.  相似文献   

5.
Bai X  Ma D  Liu A  Shen X  Wang QJ  Liu Y  Jiang Y 《Science (New York, N.Y.)》2007,318(5852):977-980
The mammalian target of rapamycin, mTOR, is a central regulator of cell growth. Its activity is regulated by Rheb, a Ras-like small guanosine triphosphatase (GTPase), in response to growth factor stimulation and nutrient availability. We show that Rheb regulates mTOR through FKBP38, a member of the FK506-binding protein (FKBP) family that is structurally related to FKBP12. FKBP38 binds to mTOR and inhibits its activity in a manner similar to that of the FKBP12-rapamycin complex. Rheb interacts directly with FKBP38 and prevents its association with mTOR in a guanosine 5'-triphosphate (GTP)-dependent manner. Our findings suggest that FKBP38 is an endogenous inhibitor of mTOR, whose inhibitory activity is antagonized by Rheb in response to growth factor stimulation and nutrient availability.  相似文献   

6.
Hypothalamic mTOR signaling regulates food intake   总被引:1,自引:0,他引:1  
The mammalian Target of Rapamycin (mTOR) protein is a serine-threonine kinase that regulates cell-cycle progression and growth by sensing changes in energy status. We demonstrated that mTOR signaling plays a role in the brain mechanisms that respond to nutrient availability, regulating energy balance. In the rat, mTOR signaling is controlled by energy status in specific regions of the hypothalamus and colocalizes with neuropeptide Y and proopiomelanocortin neurons in the arcuate nucleus. Central administration of leucine increases hypothalamic mTOR signaling and decreases food intake and body weight. The hormone leptin increases hypothalamic mTOR activity, and the inhibition of mTOR signaling blunts leptin's anorectic effect. Thus, mTOR is a cellular fuel sensor whose hypothalamic activity is directly tied to the regulation of energy intake.  相似文献   

7.
肌肉细胞蛋白质合成能力与畜禽产肉量性状有关,试验旨在探究转录因子AT富集区4B(AT-rich interaction domain 4B,ARID4B)对牛磺酸(Taurine,Tau)调节成肌细胞C2C12蛋白质合成的影响.向体外培养C2C12细胞培养液中分别添加0、60、120、180和240μmol·L-1 Tau,采用BCA(Bicinchoniic acid)蛋白定量试剂盒和SUnSET法分别检测细胞总蛋白质含量和蛋白质合成速率,采用Western blot检测细胞中蛋白质合成相关信号通路分子mTOR磷酸化变化.进一步检测添加最适浓度Tau同时转染siRNA敲低ARID4B对mTOR磷酸化和mTOR mRNA水平的影响.结果表明,Tau以剂量依赖性方式促进C2C12细胞蛋白质合成.当Tau浓度为120μmol·L-1时,蛋白质合成总量、蛋白质合成速率和mTOR磷酸化水平达到峰值,后逐渐下降.Tau显著促进ARID4B蛋白表达,敲低ARID4B后,细胞蛋白质合成以及mTOR磷酸化水平显著降低,敲低ARID4B也显著抑制Tau对蛋白质合成、mTOR磷酸化以及mTOR mRNA表达促进作用.综上,ARID4B通过正向调节mTOR mRNA表达促进mTOR磷酸化,调节C2C12细胞中蛋白质合成.  相似文献   

8.
Mammalian target of rapamycin (mTOR) is implicated in synaptic plasticity and local translation in dendrites. We found that the mTOR inhibitor, rapamycin, increased the Kv1.1 voltage-gated potassium channel protein in hippocampal neurons and promoted Kv1.1 surface expression on dendrites without altering its axonal expression. Moreover, endogenous Kv1.1 mRNA was detected in dendrites. Using Kv1.1 fused to the photoconvertible fluorescence protein Kaede as a reporter for local synthesis, we observed Kv1.1 synthesis in dendrites upon inhibition of mTOR or the N-methyl-d-aspartate (NMDA) glutamate receptor. Thus, synaptic excitation may cause local suppression of dendritic Kv1 channels by reducing their local synthesis.  相似文献   

9.
The failure of axons to regenerate is a major obstacle for functional recovery after central nervous system (CNS) injury. Removing extracellular inhibitory molecules results in limited axon regeneration in vivo. To test for the role of intrinsic impediments to axon regrowth, we analyzed cell growth control genes using a virus-assisted in vivo conditional knockout approach. Deletion of PTEN (phosphatase and tensin homolog), a negative regulator of the mammalian target of rapamycin (mTOR) pathway, in adult retinal ganglion cells (RGCs) promotes robust axon regeneration after optic nerve injury. In wild-type adult mice, the mTOR activity was suppressed and new protein synthesis was impaired in axotomized RGCs, which may contribute to the regeneration failure. Reactivating this pathway by conditional knockout of tuberous sclerosis complex 1, another negative regulator of the mTOR pathway, also leads to axon regeneration. Thus, our results suggest the manipulation of intrinsic growth control pathways as a therapeutic approach to promote axon regeneration after CNS injury.  相似文献   

10.
To detect the mammalian target of rapamycin (mTOR) expressed in Cashmere goat fetal fibroblasts (GFb), mTOR gene was cloned from Inner Mongolia Cashmere goat (Capra hircus) and expressed in Escherichia coli followed by immunizing mice with the purified recombinant protein as an immunogen to produce the anti-goat mTOR recombinant polyclonal antibody. Antiserum was collected from the immunized mice after the fifth immunization and its titer was determined with enzyme-linked immunosorbent assay (ELISA). The results showed that the recombinant polyclonal antibody had a titer 1:200 000 and could react with the mTOR expressed in GFb cells with a specific and sensitive affinity. Western blot showed that mTOR expression and phospho-mTOR (Ser 2448) activity were inhibited when GFb cells were treated with CCI-779, an mTOR specific inhibitor.  相似文献   

11.
Protein synthesis and autophagic degradation are regulated in an opposite manner by mammalian target of rapamycin (mTOR), whereas under certain conditions it would be beneficial if they occurred in unison to handle rapid protein turnover. We observed a distinct cellular compartment at the trans side of the Golgi apparatus, the TOR-autophagy spatial coupling compartment (TASCC), where (auto)lysosomes and mTOR accumulated during Ras-induced senescence. mTOR recruitment to the TASCC was amino acid- and Rag guanosine triphosphatase-dependent, and disruption of mTOR localization to the TASCC suppressed interleukin-6/8 synthesis. TASCC formation was observed during macrophage differentiation and in glomerular podocytes; both displayed increased protein secretion. The spatial coupling of cells' catabolic and anabolic machinery could augment their respective functions and facilitate the mass synthesis of secretory proteins.  相似文献   

12.
【目的】硒(Se)能否通过Nod2/MAPK/mTOR途径调控金黄色葡萄球菌诱导的奶牛乳腺上皮细胞炎性损伤,有待于进一步研究。因此本研究将探究硒对金黄色葡萄球菌(S. aureus)感染的奶牛乳腺上皮细胞(bMECs)Nod2/MAPK/mTORs信号通路中关键蛋白表达的影响,从而为阐明硒的免疫调控机制提供理论依据。【方法】首先将bMECs以10 6细胞/孔接种于6孔板中,当细胞超过80%的汇合度时,用含2、4和8 μmol·L -1浓度硒的培养基替换原来的培养基,继续孵育12 h,然后用PBS洗涤每孔3次,将S. aureus按MOI=1:1的比例加入6孔板中,继续培养0.5 h,然后收集bMECs细胞进行相关蛋白的检测。本试验共分3大组,即对照(Con)组(bMECs)、模型(Mod)组(bMECs+S. aureus)和试验组。其中试验组又分3个亚剂量组,即Low组(bMECs+2 μmol·L -1 Se+S. aureus)、Mid组(bMECs+4 μmol·L -1 Se+S. aureus)和Hig组(bMECs+8 μmol·L -1 Se+S. aureus),每组设3个重复。利用BCA蛋白测定试剂盒对收集的bMECs细胞进行总蛋白提取。应用Western blotting技术检测bMECs中Nod2和RIP2蛋白表达水平及JNK,AKT和mTOR蛋白磷酸化水平。将蛋白样品加到10%的SDS聚丙烯酰胺凝胶电泳中,上样量为20 μg/孔,之后将蛋白转移到聚偏氟乙烯(PVDF)膜上。将PVDF膜用5 mL 5%脱脂乳阻断2 h,脱脂乳脱脂后用TBST清洗后,分别用5 mL的 Nod2、RIP2、JNK、AKT、mTOR和β-actin的一抗孵育过夜,回收一抗。之后在PVDF膜中分别加入5 mL上述蛋白的二抗,室温孵育2 h,回收二抗。PVDF用TBST洗涤5次,最后在暗室条件下进行化学显影。 【结果】S. aureus能显著提高bMECs中Nod2和RIP2蛋白表达水平及JNK,AKT和mTOR蛋白磷酸化水平(P<0.01)。S. aureus感染0.5 h后,Nod2蛋白水平显著升高(P<0.01)。在培养基里添加2 μmol·L -1 的硒可极显著抑制Nod2蛋白的表达(P<0.01),在培养基里添加8 μmol·L -1 的硒可显著抑制Nod2的表达(P<0.05); S . aureus感染0.5 h后,RIP2蛋白水平显著升高(P<0.05),而在培养基里添加8 μmol·L -1 硒可显著抑制RIP2蛋白的表达(P<0.05);S. aureus感染0.5 h后,与对照组相比,模型组JNK蛋白磷酸化水平显著升高(P<0.01)。在培养基里添加4 μmol·L -1 的硒能显著抑制JNK蛋白的磷酸化水平(P<0.05),在培养基里添加8 μmol·L -1 的硒能显著抑制JNK蛋白的磷酸化水平(P<0.01); S. aureus感染0.5 h后,与对照组相比,模型组AKT蛋白磷酸化水平显著升高(P<0.01)。在培养基里添加4 μmol·L -1 硒可极显著抑制JNK蛋白的磷酸化水平(P<0.01),在培养基里添加8 μmol·L -1 硒可显著抑制AKT蛋白的磷酸化水平(P<0.05);S. aureus感染0.5 h后,模型组mTOR蛋白磷酸化水平显著升高(P<0.01)。在培养基里分别添加4 μmol·L -1 和8 μmol·L -1 硒均能显著抑制mTOR蛋白磷酸化水平(P<0.05)。 【结论】硒可通过抑制bMECs Nod2/MAPK/mTORs信号通路中关键因子蛋白的表达而减轻S. aureus诱导的bMECs炎症反应。  相似文献   

13.
The enzyme mTOR (mammalian target of rapamycin) is a major target for therapeutic intervention to treat many human diseases, including cancer, but very little is known about the processes that control levels of mTOR protein. Here, we show that mTOR is targeted for ubiquitination and consequent degradation by binding to the tumor suppressor protein FBXW7. Human breast cancer cell lines and primary tumors showed a reciprocal relation between loss of FBXW7 and deletion or mutation of PTEN (phosphatase and tensin homolog), which also activates mTOR. Tumor cell lines harboring deletions or mutations in FBXW7 are particularly sensitive to rapamycin treatment, which suggests that loss of FBXW7 may be a biomarker for human cancers susceptible to treatment with inhibitors of the mTOR pathway.  相似文献   

14.
Phosphorylation and regulation of Akt/PKB by the rictor-mTOR complex   总被引:2,自引:0,他引:2  
Deregulation of Akt/protein kinase B (PKB) is implicated in the pathogenesis of cancer and diabetes. Akt/PKB activation requires the phosphorylation of Thr308 in the activation loop by the phosphoinositide-dependent kinase 1 (PDK1) and Ser473 within the carboxyl-terminal hydrophobic motif by an unknown kinase. We show that in Drosophila and human cells the target of rapamycin (TOR) kinase and its associated protein rictor are necessary for Ser473 phosphorylation and that a reduction in rictor or mammalian TOR (mTOR) expression inhibited an Akt/PKB effector. The rictor-mTOR complex directly phosphorylated Akt/PKB on Ser473 in vitro and facilitated Thr308 phosphorylation by PDK1. Rictor-mTOR may serve as a drug target in tumors that have lost the expression of PTEN, a tumor suppressor that opposes Akt/PKB activation.  相似文献   

15.
mTOR信号通路是动物生长发育的重要调控通路之一。以尼罗罗非鱼为实验材料,研究了不同盐度梯度对尼罗罗非鱼生长的影响,以及mTOR通路下游调节因子p70s6k和4ebp1的mRNA与蛋白表达水平变化。30 d养殖结果显示,盐度增加对尼罗罗非鱼生长具有明显抑制作用,0、15、20、25盐度下,尼罗罗非鱼日均增重率分别为(0.48±0.13)g/d、(0.31±0.09)g/d、(0.14±0.08)g/d、(0.09±0.03)g/d。荧光定量PCR显示,p70s6k mRNA相对表达量随着盐度梯度升高而下降,0盐度组中表达量最高,显著高于其他盐度组(P0.05),25盐度组最低;4ebp1 mRNA相对表达量随着盐度梯度升高而升高,0盐度组中表达量最低,25盐度组最高,0盐度组与25盐度组间差异显著(P0.05)。Western blot结果显示,0盐度组中p70s6k蛋白含量显著大于其他高盐度组,而25盐度组中4ebp1蛋白含量显著大于其余低盐度组(P0.05)。结果表明,盐度可能通过介导mT OR信号通路参与尼罗罗非鱼的生长调节。  相似文献   

16.
The mammalian target of rapamycin (mTOR) signaling pathway is evolutionarily conserved, mTOR can integrate and converge a wide range of signals, including intracellular and extracellular nutrients, growth factors, energy and stress conditions, and has a crucial role in the vertebrate growth control. This review analyzed the main components and regulated factors of TOR signaling pathway, explained functions and mechanisms of roTOR during the individual growth, the development and its dynamic role, revealed its additional functions beyond the cell growth control, and finally reviewed the tissue specificity and time specificity of mTOR signaling pathway, and its regulation on sexual differentiation, tissue differentiation and organogenesis in the individual development.  相似文献   

17.
FLCN基因参与多种代谢途径和细胞过程,国内外关于FLCN在奶牛乳腺发育过程中表达及调节的研究鲜有报道。应用RNA干扰技术和质粒转染技术改变FLCN基因在奶牛乳腺上皮细胞中表达量,流式细胞仪检测细胞增殖,采用qRT-PCR和Western blot检测FLCN对泌乳相关功能基因AMPK、mTOR、CyclinD1、Caspase3和β-酪蛋白表达的影响。结果表明,FLCN正向调节mTOR磷酸化水平,促进乳蛋白合成和细胞增殖,抑制细胞凋亡,负调控能量代谢调节子AMPK。FLCN在奶牛乳腺上皮细胞中可通过mTOR信号通路调控细胞增殖及乳蛋白合成,研究对揭示FLCN调控奶牛乳腺上皮细胞增殖和泌乳具有重要作用。  相似文献   

18.
刘文娇  王涵  龚婷 《南方农业学报》2022,53(12):3498-3509
【目的】分析SP1基因在从江香猪不同组织及不同发育阶段睾丸中的表达情况及其对睾丸间质细胞自噬、凋亡的转录调控作用,为探究SP1基因调控间质细胞自噬的分子机制及提高从江香猪雄性繁殖性能提供理论基础。【方法】选取性早熟的从江香猪作为研究对象,PCR扩增得到其SP1基因编码区(CDS)序列,应用相关在线软件对CDS序列进行生物信息学分析,荧光定量PCR检测性成熟期从江香猪不同组织中SP1表达量,利用实时荧光定量PCR和Western blotting检测不同日龄从江香猪睾丸中的SP1基因表达量。【结果】生物信息学分析结果显示,SP1基因CDS序列全长为2361 bp,编码786个氨基酸残基,蛋白二级及三级结构以无规则卷曲和延伸链为主,无跨膜结构域和信号肽剪切位点,且为不稳定蛋白。SP1氨基酸序列有174个磷酸化位点,通过氨基酸同源性分析发现猪SP1与绵羊和牛的亲缘关系最近。对SP1在各组织的表达量进行检测,结果表明SP1基因相对表达量在脾脏中最高;此外,SP1的蛋白水平在180 d的香猪睾丸中有最高表达量,基因水平在30和180 d的香猪睾丸中有较高表达量。进一步构建SP1基因超表达载体,转染至从江香猪睾丸间质细胞,结果显示pEGFP-C1-SP1组的SP1相对表达量显著高于pEGFP-C1组(P<0.05,下同),而自噬通路相关因子基因mTOR、LC3B、Beclin-1和凋亡相关因子基因Caspase-3、Bcl-2的相对表达量在超表达pEGFP-C1-SP1组显著低于pEGFP-C1组,但自噬凋亡信号因子ERK1/2和凋亡基因Bax的相对表达量无显著变化(P>0.05)。推测SP1基因可通过降低LC3B、Beclin-1、Caspase-3的表达来抑制睾丸间质细胞自噬凋亡的发生,或通过降低mTOR及抗凋亡基因Bcl-2的表达来促进凋亡发生。【结论】 SP1基因在从江香猪不同组织及睾丸发育不同阶段均有表达,且通过影响睾丸间质细胞自噬、凋亡相关基因表达,而在从江香猪初情期和性成熟期发挥重要的生理学作用。  相似文献   

19.
During their growth and development, animals adapt to tremendous changes in order to survive. These include responses to both environmental and physiological changes and autophagy is one of most important adaptive and regulatory mechanisms. Autophagy is defined as an autolytic process to clear damaged cellular organelles and recycle the nutrients via lysosomic degradation. The process of autophagy responds to special conditions such as nutrient withdrawal. Once autophagy is induced, phagophores form and then elongate and curve to form autophagosomes. Autophagosomes then engulf cargo, fuse with endosomes, and finally fuse with lysosomes for maturation. During the initiation process, the ATG1/ULK1 (unc-51-like kinase 1) and VPS34 (which encodes a class III phosphatidylinositol (PtdIns) 3-kinase) complexes are critical in recruitment and assembly of other complexes required for autophagy. The process of autophagy is regulated by autophagy related genes (ATGs). Amino acid and energy starvation mediate autophagy by activating mTORC1 (mammalian target of rapamycin) and AMP-activated protein kinase (AMPK). AMPK is the energy status sensor, the core nutrient signaling component and the metabolic kinase of cells. This review mainly focuses on the mechanism of autophagy regulated by nutrient signaling especially for the two important complexes, ULK1 and VPS34.  相似文献   

20.
Gibberellin (GA) regulates growth and development in plants. We isolated and characterized a rice GA-insensitive dwarf mutant, gid2. The GID2 gene encodes a putative F-box protein, which interacted with the rice Skp1 homolog in a yeast two-hybrid assay. In gid2, a repressor for GA signaling, SLR1, was highly accumulated in a phosphorylated form and GA increased its concentration, whereas SLR1 was rapidly degraded by GA through ubiquitination in the wild type. We conclude that GID2 is a positive regulator of GA signaling and that regulated degradation of SLR1 is initiated through GA-dependent phosphorylation and finalized by an SCF(GID2)-proteasome pathway.  相似文献   

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