14-3-3 蛋白

介绍了14－3－3蛋白的基本结构和功能,并简要概述了14－3－3蛋白在信号转导,细胞周期调控以及前体蛋白的折叠与运输过程中的作用机理。     

Targeted proteomic analysis of 14-3-3σ in nasopharyngeal carcinoma

14-3-3σ is a potential tumor suppressor, and loss of 14-3-3σ expression plays an important role in carcinogenesis and metastasis. To explore the possible mechanism of 14-3-3σ in nasopharyngeal carcinoma (NPC) invasion and metastasis, targeted proteomic analysis was performed on 14-3-3σ-associated proteins from NPC cells. As the results, 112 proteins associated with 14-3-3σ were identified, and four 14-3-3σ-interacted proteins: keratin 8, epidermal growth factor receptor (EGFR), small GTP-binding protein RAB7, and p53 were confirmed by coimmunoprecipitation and Western blot analysis. The 14-3-3σ-associated proteins could be grouped into eight clusters based on their molecule functions. Protein–protein interaction (PPI) analysis indicated that 14-3-3σ/EGFR/keratin 8 interactions may be involved in the invasion and metastasis of NPC. 14-3-3σ/EGFR/keratin 8 could form complexes in NPC cells. 14-3-3σ downregulation in NPC may lead to the overexpression of EGFR and keratin 8, which increases the invasion ability of NPC cells possibly by activating the downstream signal molecules and reorganizing cytoskeleton. The data suggest that the biological functions of 14-3-3σ in NPC are diversified, and 14-3-3σ could inhibit the in vitro invasive ability of NPC cells possibly through 14-3-3σ/EGFR/keratin 8 interaction.     

14-3-3蛋白研究进展

14-3-3蛋白是高度保守的、所有真核生物细胞中都普遍存在的、在大多数生物物种中由一个基因家族编码的一类蛋白调控家族。它几乎参与生命体所有的生理反应过程,人们在各种组织细胞中发现了各种不同的14-3-3蛋白。作为与磷酸丝氨酸／苏氨酸结合的第一信号分子,14-3-3蛋白在细胞的信号转导中起着至关重要的作用,尤其是它直接参与调节蛋白激酶和蛋白磷酸化酶的活性,被称为蛋白质与蛋白质相互作用的”桥梁蛋白”;它可以与转录因子结合形成复合体,调节相关基因的表达。一些研究表明,14-3-3蛋白调控机制的紊乱可以直接导致疾病的发生,在临床上14-3-3蛋白常常可以作为诊断的标志物。     

The down-regulated expression of 14-3-3σ may activate the other six 14-3-3 isoforms and they may take over the role of 14-3-3σ in the tumor genesis

Seven isoforms of 14-3-3 protein family have different functions in the cancer genesis and progress. It is found that six isoforms were up-regulated expression and inclined to sustain the cancer survival. Conversely, 14-3-3σ strongly promotes cancer apoptosis. Its down-regulated expression was found in many cancer tissues and thought to be an early event in the tumor genesis. Interestingly, no suggestions are made about the possible effect that the down-regulated expression of 14-3-3σ activated the other six 14-3-3 isoforms and they take over the role of 14-3-3σ in the tumor genesis. The inactivation of 14-3-3σ in the early stage of tumor genesis is a clue to trigger the other six 14-3-3 isoforms activation.     

Arachidonic Acid Binds 14-3-3ζ, Releases 14-3-3ζ from Phosphorylated BAD and Induces Aggregation of 14-3-3ζ

Polyunsaturated fatty acids, like arachidonic acid, can bind proteins and affect their function. The 14-3-3 proteins bind phosphorylated sites on a diverse array of client proteins and, in this way, are involved in many intracellular signaling pathways. In this study, we used a novel approach to discover that 14-3-3ζ is able to directly bind arachidonic acid. Furthermore, arachidonic acid, at physiological concentrations, reduced the binding of 14-3-3ζ to phosphorylated BAD, an interaction that is important in regulating apoptosis. In addition, high concentrations of arachidonic acid caused the polymerization of 14-3-3ζ, an event observed in neurodegenerative disorders. Taken together, these results indicate that arachidonic acid directly interacts with 14-3-3ζ and that this interaction may be important in both normal and pathological cellular events. If so, then factors that mediate the release, metabolism and reacylation of arachidonic acid into membranes represent key points of regulation.     

植物14-3-3蛋白研究进展

14-3-3蛋白是真核生物中许多信号传导级联反应的主要调节分子,易于与具有磷酸化的丝氨酸和苏氨酸残基的靶蛋白互作进而调节碳氮代谢、三羧酸循环、莽草酸合成等多种生理过程中的多种酶活性。该文根据近年来国内外对14-3-3蛋白的研究进展,对植物中14-3-3蛋白的发现、基因鉴定、结构和功能以及14-3-3蛋白与其靶蛋白的互作机制进行综述,并对14-3-3蛋白的研究提出了进一步的展望。     

The role of epigenetic inactivation of 14-3-3σ in human cancer

Cancer cells show characteristic alterations in DNA methylation patterns. Aberrant CpG methylation of specific promoters results in inactivation of tumor suppressor genes and therefore plays an important role in carcinogenesis. The p53-regulated gene 14-3-3σ undergoes frequent epigenetic silencing in several types of cancer, including carcinoma of the breast, prostate, and skin, suggesting that the loss of 14-3-3σ expression may be causally involved in tumor progression. Functional studies demonstrated that 14-3-3σ is involved in cell-cycle control and prevents the accumulation of chromosomal damage. The recent identification of novel 14-3-3if-associated proteins by a targeted proteomics approach implies that 14-3-3σ regulates diverse cellular processes, which may become deregulated after silencing of 14-3-3σ expression in cancer cells.     

Dimerization Is Essential for 14-3-3�� Stability and Function in Vivo

Members of the conserved 14-3-3 protein family spontaneously self-assemble as homo- and heterodimers via conserved sequences in the first four (αA-αD) of the nine helices that comprise them. Dimeric 14-3-3s bind conserved motifs in diverse protein targets involved in multiple essential cellular processes including signaling, intracellular trafficking, cell cycle regulation, and modulation of enzymatic activities. However, recent mostly in vitro evidence has emerged, suggesting functional and regulatory roles for monomeric 14-3-3s. We capitalized on the simplicity of the 14-3-3 family in Drosophila to investigate in vivo 14-3-3ζ monomer properties and functionality. We report that dimerization is essential for the stability and function of 14-3-3ζ in neurons. Moreover, we reveal the contribution of conserved amino acids in helices A and D to homo- and heterodimerization and their functional consequences on the viability of animals devoid of endogenous 14-3-3ζ. Finally, we present evidence suggesting endogenous homeostatic adjustment of the levels of the second family member in Drosophila, D14-3-3ϵ, to transgenic monomeric and dimerization-competent 14-3-3ζ.     

Detection of 14-3-3ζ in cerebrospinal fluid following experimentally evoked seizures

Surrogate and peripheral (bio)markers of neuronal injury may be of value in assessing effects of seizures on the brain or epilepsy development following trauma. The presence of 14-3-3 isoforms in cerebrospinal fluid (CSF) is a diagnostic indicator of Creutzfeldt–Jakob disease but these proteins may also be present following acute neurological insults. Here, we examined neuronal and 14-3-3 proteins in CSF from rats after seizures. Seizures induced by intra-amygdala microinjection of 0.1 µg kainic acid (KA) caused damage which was mainly restricted to the ipsilateral CA3 subfield of the hippocampus. 14-3-3ζ was detected at significant levels in CSF sampled 4 h after seizures compared with near absence in control CSF. Neuron-specific nuclear protein (NeuN) was also elevated in CSF in seizure rats. CSF 14-3-3ζ levels were significantly lower in rats treated with 0.01 µg KA. These data suggest the presence of 14-3-3ζ within CSF may be a biomarker of acute seizure damage.     

14-3-3ζ Regulates Immune Response through Stat3 Signaling in Oral Squamous Cell Carcinoma

Ectopic expression of 14-3-3ζ has been found in various malignancies, including lung cancer, liver cancer, head and neck squamous cell carcinoma (HNSCC), and so on. However, the effect of 14-3-3ζ in the regulation of interactions between tumor cells and the immune system has not been previously reported. In this study, we aimed to investigate whether and how 14-3-3ζ is implicated in tumor inflammation modulation and immune recognition evasion. In oral squamous cell carcinoma (OSCC) cell lines and cancer tissues, we found that 14-3-3ζ is overexpressed. In OSCC cells, 14-3-3ζ knockdown resulted in the up-regulated expression of inflammatory cytokines. In contrast, 14-3-3ζ introduction attenuated cytokine expression in human normal keratinocytes and fibroblasts stimulated with interferon-γ (IFN-γ) and lipopolysaccharide (LPS). Furthermore, supernatants from 14-3-3ζ knockdown OSCC cells dramatically altered the response of peritoneal macrophages, dendritic cells and tumor-specific T cells. Interestingly, Stat3 was found to directly interact with 14-3-3ζ and its disruption relieved the inhibition induced by 14-3-3ζ in tumor inflammation. Taken together, our studies provide evidence that 14-3-3ζ may regulate tumor inflammation and immune response through Stat3 signaling in OSCC.     

14-3-3:保护性信号转导调节蛋白

14 3 3蛋白家族是真核细胞中高度保守的可溶性蛋白。在哺乳动物 ,14 3 3蛋白主要存在于脑。 14 3 3蛋白与许多蛋白结合 ,在细胞凋亡、生长、增殖的信号转导过程中发挥关键的调节作用 ,是细胞内重要的保护性蛋白。 14 3 3蛋白还是一些脑疾病的诊断标志。 14 3 3蛋白有可能成为治疗一些疾病的靶点     

14-3-3蛋白与植物细胞信号转导

14-3-3蛋白通过直接蛋白质-蛋白质相互作用对植物代谢关键酶、质膜H^＋ -ATP酶等发挥广泛调节作用。越来越多证据显示14-3-3蛋白通过与转录因子和其他信号分子结合参与调控植物细胞信号转导。对植物细胞中14-3-3蛋白调控信号转导途径,尤其是植物细胞对胁迫响应的调控机制进行了综述。     

Amygdala 14-3-3ζ as a novel modulator of escalating alcohol intake in mice

Alcoholism is a devastating brain disorder that affects millions of people worldwide. The development of alcoholism is caused by alcohol-induced maladaptive changes in neural circuits involved in emotions, motivation, and decision-making. Because of its involvement in these processes, the amygdala is thought to be a key neural structure involved in alcohol addiction. However, the molecular mechanisms that govern the development of alcoholism are incompletely understood. We have previously shown that in a limited access choice paradigm, C57BL/6J mice progressively escalate their alcohol intake and display important behavioral characteristic of alcohol addiction, in that they become insensitive to quinine-induced adulteration of alcohol. This study used the limited access choice paradigm to study gene expression changes in the amygdala during the escalation to high alcohol consumption in C57BL/6J mice. Microarray analysis revealed that changes in gene expression occurred predominantly after one week, i.e. during the initial escalation of alcohol intake. One gene that stood out from our analysis was the adapter protein 14-3-3ζ, which was up-regulated during the transition from low to high alcohol intake. Independent qPCR analysis confirmed the up-regulation of amygdala 14-3-3ζ during the escalation of alcohol intake. Subsequently, we found that local knockdown of 14-3-3ζ in the amygdala, using RNA interference, dramatically augmented alcohol intake. In addition, knockdown of amygdala 14-3-3ζ promoted the development of inflexible alcohol drinking, as apparent from insensitivity to quinine adulteration of alcohol. This study identifies amygdala 14-3-3ζ as a novel key modulator that is engaged during escalation of alcohol use.     

14-3-3蛋白和神经退行性疾病

14-3-3蛋白以二聚体形式存在,识别磷酸丝氨酸／苏氨酸连接的信号分子,通过与其配体蛋白质相互作用,参与细胞信号转导、细胞周期调控和细胞问运输。14-3-3蛋自在脑组织中含量丰富,所有神经元、星形胶质细胞、少突肢质细胞、小胶质细胞的胞液与胞核中都有表述。14-3-3蛋白与神经退行性疾病阿尔茨海默病和帕金森病的发生过程关系密切。     

14-3-3? and 14-3-3σ Inhibit Toll-like Receptor (TLR)-mediated Proinflammatory Cytokine Induction

Toll-like receptors (TLRs) are a group of pattern recognition receptors that play a crucial role in the induction of the innate immune response against bacterial and viral infections. TLR3 has emerged as a key sensor of viral double-stranded RNA. Thus, a clearer understanding of the biological processes that modulate TLR3 signaling is essential. Limited studies have applied proteomics toward understanding the dynamics of TLR signaling. Herein, a proteomics approach identified 14-3-3ϵ and 14-3-3σ proteins as new members of the TLR signaling complex. Toward the functional characterization of 14-3-3ϵ and 14-3-3σ in TLR signaling, we have shown that both of these proteins impair TLR2, TLR3, TLR4, TLR7/8, and TLR9 ligand-induced IL-6, TNFα, and IFN-β production. We also show that 14-3-3ϵ and 14-3-3σ impair TLR2-, TLR3-, TLR4-, TLR7/8-, and TLR9-mediated NF-κB and IFN-β reporter gene activity. Interestingly, although the 14-3-3 proteins inhibit poly(I:C)-mediated RANTES production, 14-3-3 proteins augment Pam₃CSK₄, LPS, R848, and CpG-mediated production of RANTES (regulated on activation normal T cell expressed and secreted) in a Mal (MyD88 adaptor-like)/MyD88-dependent manner. 14-3-3ϵ and 14-3-3σ also bind to the TLR adaptors and to both TRAF3 and TRAF6. Our study conclusively shows that 14-3-3ϵ and 14-3-3σ play a major regulatory role in balancing the host inflammatory response to viral and bacterial infections through modulation of the TLR signaling pathway. Thus, manipulation of 14-3-3 proteins may represent novel therapeutic targets for inflammatory conditions and infections.     

Determinants of 14-3-3σ Protein Dimerization and Function in Drug and Radiation Resistance

Many proteins exist and function as homodimers. Understanding the detailed mechanism driving the homodimerization is important and will impact future studies targeting the “undruggable” oncogenic protein dimers. In this study, we used 14-3-3σ as a model homodimeric protein and performed a systematic investigation of the potential roles of amino acid residues in the interface for homodimerization. Unlike other members of the conserved 14-3-3 protein family, 14-3-3σ prefers to form a homodimer with two subareas in the dimeric interface that has 180° symmetry. We found that both subareas of the dimeric interface are required to maintain full dimerization activity. Although the interfacial hydrophobic core residues Leu¹² and Tyr⁸⁴ play important roles in 14-3-3σ dimerization, the non-core residue Phe²⁵ appears to be more important in controlling 14-3-3σ dimerization activity. Interestingly, a similar non-core residue (Val⁸¹) is less important than Phe²⁵ in contributing to 14-3-3σ dimerization. Furthermore, dissociating dimeric 14-3-3σ into monomers by mutating the Leu¹², Phe²⁵, or Tyr⁸⁴ dimerization residue individually diminished the function of 14-3-3σ in resisting drug-induced apoptosis and in arresting cells at G₂/M phase in response to DNA-damaging treatment. Thus, dimerization appears to be required for the function of 14-3-3σ.     

Impairment of GABAB receptor dimer by endogenous 14-3-3ζ in chronic pain conditions

In the central nervous system, the inhibitory GABAB receptor is the archetype of heterodimeric G protein-coupled receptors (GPCRs). However, the regulation of GABAB dimerization, and more generally of GPCR oligomerization, remains largely unknown. We propose a novel mechanism for inhibition of GPCR activity through de-dimerization in pathological conditions. We show here that 14-3-3ζ, a GABAB1-binding protein, dissociates the GABAB heterodimer, resulting in the impairment of GABAB signalling in spinal neurons. In the dorsal spinal cord of neuropathic rats, 14-3-3ζ is overexpressed and weakens GABAB inhibition. Using anti-14-3-3ζ siRNA or competing peptides disrupts 14-3-3ζ/GABAB1 interaction and restores functional GABAB heterodimers in the dorsal horn. Importantly, both strategies greatly enhance the anti-nociceptive effect of intrathecal Baclofen in neuropathic rats. Taken together, our data provide the first example of endogenous regulation of a GPCR oligomeric state and demonstrate its functional impact on the pathophysiological process of neuropathic pain sensitization.