AP-1的研究进展

激活蛋白-1(activator protein-1,AP-1)是细胞内一类转录激活因子,主要由原癌基因编码的蛋白质Jun和Fos组成,以同源或异源二聚体复合物形式结合DNA靶序列,调控靶基因表达。AP-1通过调节靶基因表达来应对多种刺激(包括细胞因子、生长因子、压力及细菌和病毒感染等)对细胞的影响,参与调节细胞增殖、分化、凋亡以及炎症等多种细胞过程。该文就AP-1的结构特点、生物学功能、活性调控及其在医学研究中的应用作一综述。     

Regulation of Steatohepatitis and PPARγ Signaling by Distinct AP-1 Dimers

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Distinct and Overlapping Roles for AP-1 and GGAs Revealed by the “Knocksideways” System

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Highlights? AP-1 knocksideways depletes ～100 proteins from clathrin-coated vesicles (CCVs) ? GGA2 knocksideways mainly depletes hydrolases and their receptors ? GGA2 depends on AP-1 for incorporation into CCVs ? AP-1 acts as a linchpin for intracellular CCV formation and is bidirectional     

Theoretical studies on pyrimidine substituent derivatives as dual inhibitors of AP-1 and NF-κB

Theoretical studies on the three-dimensional (3D) quantitative structure-activity relationship (QSAR) and mechanisms of action of a series of pyrimidine substituent derivatives as dual inhibitors of AP-1 and NF-κB were carried out using comparative molecular field analysis (CoMFA) and docking methods. The established 3D-QSAR model exhibits a satisfying statistical quality and prediction ability. Docking results show somewhat lower average values of the flexible and rigid energy scores in the chosen binding sites. The docking analysis offers appropriate orientations and conformations of these compounds at the binding sites to both AP-1 and NF-κB in good agreement with the 3D-QSAR model from CoMFA. The combined CoMFA and docking study suggests the following substituent selections: substituent R₂ should be a kind of H–N–thienyl or CH₃–N–thienyl group; substituent R₅ should be a kind of COO–tBu or COOEt group; and substituent R₄ should be a CH₂CH₃ or 2-thienyl group. The docking analysis also shows that the binding sites fall just at the joint regions between AP-1 (or NF-κB) and DNA, where these compounds can effectively prevent free AP-1 and NF-κB from binding to DNA, and this may be the reason that derivatives with pyrimidine substituents have an inhibition function. In addition, a very interesting finding was that the binding sites of both AP-1 and NF-κB have a common structural characteristic, thereby providing a reasonable explanation for the dual inhibition functions of these compounds towards both AP-1 and NF-κB. These theoretical results help to deepen our understanding of the inhibition mechanism of these pyrimidine substituent derivatives, and will aid in directing further drug-molecular design.     

EB病毒LMP-1上调鼻咽癌细胞系AP-1的活性

为了探讨 EB病毒潜伏膜蛋白 1 ( LMP- 1 )通过信号传导途径介导的致瘤分子机制 ,由此首先构建了 AP- 1报告基因 ,用佛波酯诱导确定了其报道 AP- 1的功能 ;通过建立荧光素酶双报道系统 ,研究了 LMP- 1表达对 AP- 1和 NFκB活性的影响 .研究发现 :在 LMP- 1阴性鼻咽癌 ( NPC)细胞系 ,导入 LMP- 1表达质粒后 ,AP- 1和 NFκB的活性均升高 4～ 5倍 ;而在 LMP- 1阳性 NPC细胞系中 ,当导入 LMP- 1反义表达质粒 ,AP- 1和 NFκB的活性则受抑制 ,活性下调 3～ 4倍 .结果表明 ,LMP- 1能上调 NPC细胞系 AP- 1的活性 ,同时再次证实了 LMP- 1能活化 NFκB.     

Kolaviron inhibits dimethyl nitrosamine-induced liver injury by suppressing COX-2 and iNOS expression via NF-κB and AP-1

AimsKolaviron, a bioflavonoid isolated from the seeds of Garcinia kola has been reported to possess anti-inflammatory, antioxidant, antigenotoxic and hepatoprotective activities in model systems via multiple biochemical mechanisms. The present study investigated the possible molecular mechanisms underlying the hepatoprotective effects of kolaviron.Main methodsBiomarkers of hepatic oxidative injury, histological and immunohistochemical techniques were used. In addition, the protein expression levels of cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) were evaluated by western blotting while DNA-binding activities of nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1) were determined by electrophoretic mobility shift assay.Key findingsKolaviron administered orally at doses of 100 and 200 mg/kg for 7 days significantly lowered the activities of serum transaminases and γ-glutamyl tranferase induced by single intraperitoneal administration of dimethyl nitrosamine (DMN) (20 mg/kg) and preserved the integrity of the hepatocytes. Also, kolaviron at both doses reduced the DMN induced elevated hepatic levels of malondialdehyde and reversed DMN mediated decrease in hepatic glutathione. The hepatoprotective effect of kolaviron was compared to that of curcumin, an established hepatoprotective agent. Kolaviron inhibited the DMN induced expression of COX-2 and iNOS. Immunohistochemical staining of rat liver verified the inhibitory effect of kolaviron on DMN-induced hepatic COX-2 expression. Furthermore, kolaviron abrogated DMN induced binding activity of NF-κB as well as AP-1.SignificanceThe ability of kolaviron to inhibit COX-2 and iNOS expression through down regulation of NF-κB and AP-1 DNA binding activities could be a mechanism for the hepatoprotective properties of kolaviron.     

NF-κB- and AP-1-mediated DNA looping regulates osteopontin transcription in endotoxin-stimulated murine macrophages

Osteopontin (OPN) is expressed by various immune cells and modulates both innate and adaptive immune responses. However, the molecular mechanisms that control opn gene expression, especially at the chromatin level, remain largely unknown. We have previously demonstrated many specific cis- and trans-regulatory elements that determine the extent of endotoxin (LPS)-mediated induction of OPN synthesis in murine macrophages. In the present study, we confirm that NF-κB also plays an important role in the setting of LPS-stimulated OPN expression through binding to a distal regulatory element. Importantly, we demonstrate that LPS stimulates chromosomal loops in the OPN promoter between NF-κB binding site and AP-1 binding site using chromosome conformation capture technology. The crucial role of NF-κB and AP-1 in LPS-stimulated DNA looping was confirmed, as small interfering RNA knock-down of NF-κB p65 and AP-1 c-Jun exhibited decreased levels of DNA looping. Furthermore, we demonstrate that p300 can form a complex with NF-κB and AP-1 and is involved in DNA looping and LPS-induced OPN expression. Therefore, we have identified an essential mechanism to remodel the local chromatin structures and spatial conformations to regulate LPS-induced OPN expression.     

AP-1在腋臭患者发病过程中的作用

目的：腋臭是美容整形外科的常见病,目前发病机制尚不明确,已证实人体大汗腺中的载脂蛋白D（ApoD）在腋臭患者大汗腺中高表达,并且与腋臭的发生密切相关。探明ApoD在大汗腺细胞中的信号转导通路,可以进一步明确其在腋臭发病过程中的作用机制。JNK信号转导通路与多种疾病的发生有关。课题组前期已经做了JNKl对ApoD调控作用的相关研究,证明了在腋臭发病过程中JNK1是通过调控ApoD的转录来上调ApoD的表达。本实验在课题组前期研究基础上,探讨JNKl下游转录因子AP-1是否在JNKl上调ApoD通路中发挥作用。方法：取腋臭志愿者腋区皮肤组织,进行汗腺细胞培养。把汗腺细胞分为5．二氢睾酮处理组、5-二氢睾酮联合姜黄素处理组和空白对照3个组,用姜黄素抑制AP-1的活性,通过Real．timePCR实验方法检测ApoD在姜黄素抑制下的表达变化。结果：在姜黄素的抑制下,ApoD表达明显降低。在体外培养汗腺细胞加入5．二氢睾酮联合姜黄素处理后,ApoD的表达量在mRNA水平低于单独的5-二氢睾酮处理组和正常对照组（P〈0．05）。结论：姜黄素抑制了AP．1的活化导致ApoD的表达降低。在腋臭的发病过程中,JNKl的下游转录因子AP-1对ApoD有明显的上调作用。AP-1可能在JNKl上调ApoD这条通路中扮演了很重要的角色,它可能是JNK1和ApoD的中间转录因子。     

Trafficking of the Menkes copper transporter ATP7A is regulated by clathrin-, AP-2–, AP-1–, and Rab22-dependent steps

The transporter ATP7A mediates systemic copper absorption and provides cuproenzymes in the trans-Golgi network (TGN) with copper. To regulate metal homeostasis, ATP7A constitutively cycles between the TGN and plasma membrane (PM). ATP7A trafficking to the PM is elevated in response to increased copper load and is reversed when copper concentrations are lowered. Molecular mechanisms underlying this trafficking are poorly understood. We assess the role of clathrin, adaptor complexes, lipid rafts, and Rab22a in an attempt to decipher the regulatory proteins involved in ATP7A cycling. While RNA interference (RNAi)–mediated depletion of caveolin 1/2 or flotillin had no effect on ATP7A localization, clathrin heavy chain depletion or expression of AP180 dominant-negative mutant not only disrupted clathrin-regulated pathways, but also blocked PM-to-TGN internalization of ATP7A. Depletion of the μ subunits of either adaptor protein-2 (AP-2) or AP-1 using RNAi further provides evidence that both clathrin adaptors are important for trafficking of ATP7A from the PM to the TGN. Expression of the GTP-locked Rab22a_Q64L mutant caused fragmentation of TGN membrane domains enriched for ATP7A. These appear to be a subdomain of the mammalian TGN, showing only partial overlap with the TGN marker golgin-97. Of importance, ATP7A remained in the Rab22a_Q64L-generated structures after copper treatment and washout, suggesting that forward trafficking out of this compartment was blocked. This study provides evidence that multiple membrane-associated factors, including clathrin, AP-2, AP-1, and Rab22, are regulators of ATP7A trafficking.     

Melittin suppresses PMA-induced tumor cell invasion by inhibiting NF-κB and AP-1-dependent MMP-9 expression

Matrix metalloproteinase-9 (MMP-9) plays an important role in the invasion and metastasis of cancer cells. In this study, we examined the inhibitory effect of bee venom (BV) and its major peptides, melittin and apamin, on PMA-induced invasion induced by MMP-9 expression in Caki-1 renal cancer cells. BV and melittin, but not apamin, significantly suppressed PMA-induced invasion by inhibiting MMP-9 expression in Caki-1 cells. Furthermore, as evidenced by MMP-9 promoter assays, melittin inhibited MMP-9 gene expression by blocking the PMA-stimulated activations of activator protein-1 (AP-1) and nuclear factor-kappa B (NF-κB). In addition, melittin suppressed the PMA-induced phosphorylations of ERK and JNK mitogenactivated protein kinases, upstream factors involved in Ap-1 and NF-κB. These results suggest that the suppression of MMP-9 expression contributes to the anti-tumor properties of melittin.     

IL-1β Promotes Corneal Epithelial Cell Migration by Increasing MMP-9 Expression through NF-κB- and AP-1-Dependent Pathways

Interleukin-1β (IL-1β) plays a critical mediator in the pathogenesis of eye diseases. The implication of IL-1β in inflammatory responses has been shown to be mediated through up-regulation of inflammatory genes, including matrix metalloproteinase-9 (MMP-9). However, the detailed mechanisms of IL-1β-induced MMP-9 expression in Statens Seruminstitut Rabbit Corneal Cells (SIRCs) are largely unclear. Here, we demonstrated that in SIRCs, IL-1β induced MMP-9 promoter activity and mRNA expression associated with an increase in the secretion of pro-MMP-9. IL-1β-induced pro-MMP-9 expression and MMP-9 mRNA levels were attenuated by pretreatment with the inhibitor of MEK1/2 (U0126), JNK1/2 (SP600125), NF-κB (Bay11-7082), or AP-1 (Tanshinone IIA) and transfection with siRNA of p42 or JNK2. Moreover, IL-1β markedly stimulated p42/p44 MAPK and JNK1/2 phosphorylation in SIRCs. In addition, IL-1β also enhanced p42/p44 MAPK translocation from the cytosol into the nucleus. On the other hand, IL-1β induced c-Jun and c-Fos mRNA expression, c-Jun phosphorylation, and AP-1 promoter activity. NF-κB translocation, IκBα degradation, and NF-κB promoter activity were also enhanced by IL-1β. Pretreatment with U0126 or SP600125 inhibited IL-1β-induced AP-1 and NF-κB promoter activity, but not NF-κB translocation from the cytosol into the nucleus. Finally, we established that IL-1β could stimulate SIRCs migration via p42/p44 MAPK-, JNK1/2-, AP-1-, and NF-κB-dependent MMP-9 induction. These results suggested that NF-κB and AP-1 activated by JNK1/2 and p42/p44 MAPK cascade are involved in IL-1β-induced MMP-9 expression in SIRCs.