藏红花素调节cAMP/PKA/CREB信号通路改善抑郁症大鼠的抑郁样行为

目的 探索藏红花素（crocin）通过调节环磷酸腺苷（cAMP）/蛋白激酶A(PKA)/cAMP反应元件结合蛋白（CREB）信号通路改善抑郁症大鼠抑郁样行为的机制。方法 采用慢性温和不可预知应激（chronic unpredictable mild stress,CUMS）刺激制备抑郁症大鼠模型。在CUMS模型基础上,分别给予藏红花素、腺苷酸环化酶抑制剂SQ22536干预。通过悬尾实验、强迫游泳实验、糖水偏好实验和旷场实验检测大鼠抑郁样行为;免疫组织化学染色检测海马神经元丢失情况;ELISA法检测脑组织去甲肾上腺素与5-羟色胺等神经递质、cAMP水平及血清和脑组织IL-1β、TNF-α等炎症因子水平;免疫印迹法检测脑组织cAMP/PKA/CREB信号通路相关蛋白水平。结果 在CUMS刺激下,大鼠悬尾和游泳不动时间显著延长,糖水偏好度和活动次数显著减少,海马神经元数目显著降低,脑组织5-HT、NE和cAMP水平显著下降,p-PKA/PKA和p-CREB/CREB蛋白水平显著下调,同时IL-1β和TNF-α水平显著升高。藏红花素干预后,大鼠悬尾和游泳不动时间缩短,糖水偏好度和活动次数增加,海马神经元数目增多,脑组织5-HT、NE和cAMP水平升高,p-PKA/PKA和p-CREB/CREB蛋白表达上调,IL-1β和TNF-α水平降低。SQ22536干预逆转藏红花素的作用。结论 藏红花素通过激活cAMP/PKA/CREB信号通路,减轻抑郁症大鼠的炎症反应和海马神经元缺失,从而改善其抑郁样行为。     

低氧预适应下BDNF/TrkB和cAMP/PKA信号通路调控电压依赖性钙离子通道的研究进展

本文探析了低氧预适应对神经系统的保护作用尤其是改善学习记忆能力的相关机制,回顾了电压依赖性钙离子通道在神经系统中的作用以及与学习记忆之间的关系。重点总结了低氧预适应诱导下电压依赖性钙离子通道特性的变化情况,并深入归纳了BDNF/TrkB和cAMP/PKA信号通路对电压依赖性钙离子通道的调节机制以及低氧预适应与这些信号通路之间的关系。通过总结低氧预适应调控BDNF/TrkB和cAMP/PKA信号通路影响电压依赖性钙离子通道相关的最新研究进展,为将来阐明低氧预适应提升认知能力的可能机制奠定理论基础。     

细胞骨架与细胞凋亡及细胞内信息通路的关系

细胞骨架是细胞内最高级的组织者和管理者,根据功能将各种细胞器相对集中在细胞内的某一区域,并通过多种信息通路相互联系,使细胞内部形成一个"城市",各服务器进行有序的工作.此时,一些信号通过一定的作用模式,如诱导因素通过第二信使系统将信号传入细胞内,最终汇集到公共通道,改变细胞基因表达的类型、水平及其时序性,最后导致生理反应或程序性细胞死亡中特征性生物化学改变,但这种细胞内外的信号-受体-胞内传递-基因转录-应答反应的传递方式并不是一条龙式的单一联系,各条途径之间存在着多方式、多水平的横向联系和交互作用,形成信号传递网络.基于细胞骨架在细胞内的特殊地位和功能,可以相信,通过对细胞骨架及其与细胞内某些分子关系的研究,将有助于深入了解细胞内的信息传递规律,为揭示细胞内分子在体现细胞生物学特性方面的有机联系提供证据.     

mTORC2调节细胞骨架的信号通路

近几年来,关于哺乳动物雷帕霉素靶（mammalian target of rapamycin,mTOR）在各种哺乳动物细胞中调节肌动蛋白微丝极化及肌球蛋白微丝网形成的研究一直在不断地取得新的进展。尽管到目前为止,包括mTORC2上游和下游在内的相关的调控路径还未明确,但是因为mTORC6,的物学多样性,使其成为了当今生物学研究的焦点之一。基于长久以来特别是近五年对mTORC2的研究,在涉及细胞运动迁移、增殖分化、蛋白质合成、凋亡及自噬等生物学功能的研究中,一些重要的下游相关调控分子和蛋白相继被发现,比如P—Rexl／2、Rho家族GTPases、PKC、cAMP、p27kip1等。该综述着重总结了mTORC2实现这些生物学功能所可能通过的四条路径。当然,仍然需要大量的实验数据和研究证据进一步地证实和完善这些已经发现的可能存在的路径。     

db—cAMP对转化细胞钙调素基因表达与细胞骨架的影响

We have demonstrated that the distribution of microtubules (MT), microfilaments (MF) and fibronectin (FN) were diminished, while the gene expression of the calmodulin and c-fos enhanced in the transformed C3 H10 T1/2 cells. After treatment with 1 mM db-cAMP for 1 hr. and 2 hrs., there was an early and rapidly reduced in gene expression of calmodulin and c-fos respectively. After db-cAMP treatment for 4-5 days, the number of Capping cells of ConA binding decreased significantly and the cell surface microvilli decreased also. The growth of treated cells was inhibited markedly. By using 4F1 cDNA probe, which is preferentially expressed in G1 phase, we have found that the db-cAMP treated cells were accumulated at G1 phase. Of particular interest is the fact that the distribution of microtubules, microfilaments and fibronectin were recovered after treatment with 1 mM db-cAMP for 6 days. It is suggested that the inhibition of proliferation, alteration of phenotype and recovery of cytoskeleton in transformed cells after treatment with db-cAMP are related to the inhibition of gene expression of calmodulin.     

cAMP信号通路在抑郁症发病机制及干预策略中的研究进展

抑郁症是目前普遍存在的一种精神类疾病,给患者生活质量带来负面影响的同时,也给社会带来严重的经济负担。近年来,基于信号传导通路来干预抑郁症的策略引起社会广泛关注,其中cAMP通路作为一个重要的细胞信号通路,在抑郁症的发病机制和干预过程中起着关键作用。因此,就近年来有关基于cAMP通路干预抑郁症的研究进行综述,为调控cAMP通路及其级联影响抑郁症的作用机制提供理论依据。     

Rho GTPase对细胞骨架及信号通路的多重影响

Rho GTPase最基本的功能是结合和水解鸟嘌呤核苷酸，目前已从晡乳动物中分离出16种不同的Rho GTPases，其中以Rho、Rac和Cdc42最为人们关注。研究发现Rho GTPases参与基因转录、细胞周期进程的调控及多条信号通路的调节，与细胞凋亡、肿瘤侵润及细胞骨架构成关系密切。现普遍认为Rho GTPases是调节细胞功能的一类重要蛋白分子，越来越多的Rho家族成员及其调控的蛋白数量逐渐被发现和认识。     

灰飞虱LWO/AC/cAMP/PKA信号通路调控细胞色素P450基因表达介导对溴氰菊酯抗性

【目的】前期研究发现灰飞虱Laodelphax striatellus抗溴氰菊酯品系JH-del中CYP6AY3v2和CYP439A1v3的过量表达是灰飞虱对溴氰菊酯产生抗性的主要机制。本研究旨在阐明灰飞虱CYP6AY3v2和CYP439A1v3上调表达的机理,揭示其调控信号通路。【方法】通过定量PCR检测灰飞虱G蛋白偶联受体(G protein-coupled receptor, GPCR)A家族长波敏感视蛋白(long wavelength-sensitive opsin, LWO)基因LWO在灰飞虱溴氰菊酯抗性品系JH-del和敏感品系JHS 4龄若虫中的表达量;通过RNAi和盐酸布比卡因干扰灰飞虱JH-del品系3龄若虫LWO/AC/cAMP/PKA信号通路基因LWO,AC-2,AC-3,PKA-1,PKA-2和PKA-3,利用生物测定检测灰飞虱对溴氰菊酯敏感性的变化,验证LWO通过增加自身表达量激活下游AC/cAMP/PKA/CYP450s信号通路基因,介导灰飞虱对溴氰菊酯产生抗性。利用转基因果蝇Drosophila结合GAL4/UAS系统和昆虫杆状病毒表达系统分别在黑腹果蝇Drosophila melanogaster 3日龄雌成虫和草地贪夜蛾Spodoptera frugiperda Sf9细胞中异源表达灰飞虱LWO并验证其功能。【结果】LWO在抗溴氰菊酯灰飞虱品系JH-del中的相对表达量是敏感品系JHS中的1.54倍;与对照组(喂食dsGFP)比,喂食目标基因dsRNA干扰灰飞虱品系JH-del 3龄若虫中LWO/AC/cAMP/PKA信号通路中的任何一个节点,该信号通路下游代谢溴氰菊酯的灰飞虱CYP6AY3v2和CYP439A1v3的表达量都显著下降,灰飞虱JH-del品系3龄若虫对溴氰菊酯的敏感性都得以恢复。将灰飞虱LWO分别在黑腹果蝇和Sf9细胞中异源表达后,黑腹果蝇和Sf9细胞对溴氰菊酯的抗性也显著提高,抗性的提高也是通过灰飞虱LWO/AC/cAMP/PKA/CYP450s信号通路介导的。【结论】LWO受体通过增加自身表达量激活下游AC/cAMP/PKA/CYP450s信号通路,介导了灰飞虱对溴氰菊酯抗性的产生,该研究结果为灰飞虱抗性的治理和杀虫剂新靶标的筛选提供了理论依据。     

大豆异黄酮对大鼠乳腺癌细胞内cAMP/PKA信号途径的影响

本实验研究了大豆异黄酮对SHZ-88大鼠乳腺癌细胞内cAMP／PKA信号途径的影响。实验设3组：空白对照组、50μg／ml大豆黄酮及15μg／ml染料木素组。采用放射免疫测定法（RIA）检测了胞内cAMP的浓度、腺苷酸环化酶（adenylate cyclase,AC）和磷酸二酯酶（phosphodiesterase,PDE）的活性,用（γ-^32P）ATP掺入法测定cAMP依赖性PKA的活性,半定量RT-PCR法分析cAMP反应元件结合蛋白（cAMP response element binding protein,CREB）mRNA表达的变化。结果表明：在处理后5min,大豆黄酮组和染料木素组细胞的cAMP浓度分别比对照组升高了9．5％和11．0％（P〈0．05）：10min时,分别比对照组升高31．0％和40.3％（P〈0．01）。3组细胞的AC活性在处理时间内没有明显变化。但在处理后5min,大豆黄酮组和染料木素组细胞的PDE活性分别降至对照组的71．8％和71．6％（P〈0．05）。处理后20min,大豆黄酮组和染料木素组细胞PKA活性分别上升到对照组的125．8％和122．3％（P〈0．05）;到40min时仍维持在高水平。大豆黄酮组和染料木素组细胞CREB mRNA的表达量在处理后3h分别比对照组增加31．6％和51．1％（P〈0．05）;6h后开始下降。这些结果提示,大豆异黄酮能够激活大鼠乳腺癌细胞内cAMP／PKA信号途径;而且是通过抑制磷酸二酯酶的活性,导致胞内cAMP浓度升高而实现的。     

双歧杆菌调节VIP/cAMP/PKA和mTOR通路改善溃疡性结肠炎小鼠的实验研究

摘要 目的：探讨双歧杆菌MIMBb75通过调节血管活性肠肽（VIP）/环磷酸腺苷（cAMP）/蛋白激酶A（PKA）和哺乳动物雷帕霉素靶蛋白（mTOR）通路对溃疡性结肠炎（UC）小鼠的影响。方法：BALB/c小鼠随机分为正常对照（NC）组、结肠炎模型（UC）组、Mesalazine组和MIMBb75低、高剂量组、MIMBb75高剂量+VIP antagonist组、MIMBb75高剂量+MHY1485组（每组10只）,除NC组外均采用5%葡聚糖硫酸钠（DSS）诱导UC模型。治疗结束后,观察小鼠的一般情况及UC疾病活动指数（DAI）,检测小鼠肠道组织病理损伤、结肠组织中髓过氧化物酶（MPO）活性、肠道菌群多样性（Chao指数、Shannon指数和Simpson指数）及结肠组织VIP、cAMP、PKA、水通道蛋白3（AQP3）、mTOR、核糖体蛋白S6激酶（S6K1）的mRNA和蛋白水平。结果：与UC组相比,MIMBb75低、高剂量组和Mesalazine组小鼠的体重升高、DAI评分降低,组织病理损伤得到改善,结肠长度增加,MPO活性降低,Chao指数、Shannon指数和Simpson指数升高;VIP、cAMP、PKA、AQP3的mRNA水平和VIP、cAMP、AQP3蛋白的表达及PKA的磷酸化水平升高,mTOR和S6K1 mRNA及其蛋白的磷酸化水平降低（P<0.05）。与MIMBb75高剂量组相比,MIMBb75高剂量+VIP antagonist组VIP、cAMP、PKA、AQP3的mRNA水平和VIP、cAMP、AQP3蛋白的表达及PKA的磷酸化水平降低（P<0.05）;MIMBb75高剂量+MHY1485组mTOR和S6K1 mRNA及其蛋白的磷酸化水平升高（P<0.05）。VIP antagonist和MHY1485均能逆转MIMBb75对UC小鼠的保护作用,使其结肠损伤加重,MPO活性增高（P<0.05）。结论：双歧杆菌可改善UC小鼠的结肠损伤,增加肠道菌群的多样性,这可能与激活VIP/cAMP/PKA通路、抑制mTOR通路有关。     

cAMP/PKA signalling reinforces the LATS–YAP pathway to fully suppress YAP in response to actin cytoskeletal changes

Actin cytoskeletal damage induces inactivation of the oncoprotein YAP (Yes‐associated protein). It is known that the serine/threonine kinase LATS (large tumour suppressor) inactivates YAP by phosphorylating its Ser127 and Ser381 residues. However, the events downstream of actin cytoskeletal changes that are involved in the regulation of the LATS–YAP pathway and the mechanism by which LATS differentially phosphorylates YAP on Ser127 and Ser381 in vivo have remained elusive. Here, we show that cyclic AMP (cAMP)‐dependent protein kinase (PKA) phosphorylates LATS and thereby enhances its activity sufficiently to phosphorylate YAP on Ser381. We also found that PKA activity is involved in all contexts previously reported to trigger the LATS–YAP pathway, including actin cytoskeletal damage, G‐protein‐coupled receptor activation, and engagement of the Hippo pathway. Inhibition of PKA and overexpression of YAP cooperate to transform normal cells and amplify neural progenitor pools in developing chick embryos. We also implicate neurofibromin 2 as an AKAP (A‐kinase‐anchoring protein) scaffold protein that facilitates the function of the cAMP/PKA–LATS–YAP pathway. Our study thus incorporates PKA as novel component of the Hippo pathway.     

Cadherin-Mediated Transmembrane Interactions

We show in this study that cadherin ligands, either soluble or immobilized on different surfaces, can bind to cells carrying a compatible cadherin and induce long-range signals which affect cell adhesion and dynamics. Addition of recombinant N-cadherin extracellular domain (NEC) to CHO cells expressing N-cadherin (FL4) greatly enhanced the calcium-dependent aggregation of the cells and blocked their migration into an “in vitro wound”. Monoclonal antibody which blocks cadherin interactions inhibited the aggregation of suspended FL4 cells and facilitated the “wound closure”. As previously shown (Levenberg et al., 1998) synthetic beads coupled to NEC interacted specifically with the surface of FL4 cells and significantly enhanced the formation of adherens junctions. This effect was obtained also with the parental CHO cells, which contain low levels of N-cadherin, and in additional N-cadherin expressing cells such as cultured myoblasts. We further show here that stimulation of adhesion is not affected by the geometry of the NEC-bound surface and that cells plated on flat NEC-coated substratum also develop enhanced adherens junctions. Interaction of cells expressing low levels of endogenous N-cadherin, such as CHO cells with surface-immobilized N-cadherin ligands had a prominent effect also on the total level of N-cadherin and β-catenin in the cells, probably due to stabilization of the cadherin-catenin complex by the interaction with the external surface.     

植物病原真菌环磷酸腺苷信号通路研究进展

环磷酸腺苷(cyclic adenosine monophosphate, cAMP)是广泛存在于真核生物中的第二信使,其由腺苷酸环化酶(adenylate cyclase, AC)合成后,通过结合蛋白激酶A (protein kinase A, PKA)调控下游蛋白活性,从而参与植物病原真菌的生长发育、致病性(或致病力)、细胞壁完整性、环境胁迫响应及有性/无性生殖等方面的调控。本文介绍了植物病原真菌cAMP信号通路的信号转导及其与细胞中其他信号通路之间的交叉调控的相关研究进展,同时阐述了cAMP信号通路在植物病原真菌侵染过程中的重要作用。为今后以cAMP信号通路相关基因或蛋白作为靶点筛选抑制植物病原真菌的药物,以及利用cAMP信号通路对植物病原真菌生长发育及致病等相关调控机制进行病害防控提供了新的策略和思路。     

Microtubule targeting of substrate contacts promotes their relaxation and dissociation.

We recently showed that substrate contact sites in living fibroblasts are specifically targeted by microtubules (Kaverina, I., K. Rottner, and J.V. Small. 1998. J. Cell Biol. 142:181-190). Evidence is now provided that microtubule contact targeting plays a role in the modulation of substrate contact dynamics. The results are derived from spreading and polarized goldfish fibroblasts in which microtubules and contact sites were simultaneously visualized using proteins conjugated with Cy-3, rhodamine, or green fluorescent protein.For cells allowed to spread in the presence of nocodazole the turnover of contacts was retarded, as compared with controls and adhesions that were retained under the cell body were dissociated after microtubule reassembly. In polarized cells, small focal complexes were found at the protruding cell front and larger adhesions, corresponding to focal adhesions, at the retracting flanks and rear. At retracting edges, multiple microtubule contact targeting preceded contact release and cell edge retraction. The same effect could be observed in spread cells, in which microtubules were allowed to reassemble after local disassembly by the application of nocodazole to one cell edge. At the protruding front of polarized cells, focal complexes were also targeted and as a result remained either unchanged in size or, more rarely, were disassembled. Conversely, when contact targeting at the cell front was prevented by freezing microtubule growth with 20 nM taxol and protrusion stimulated by the injection of constitutively active Rac, peripheral focal complexes became abnormally enlarged. We further found that the local application of inhibitors of myosin contractility to cell edges bearing focal adhesions induced the same contact dissociation and edge retraction as observed after microtubule targeting.Our data are consistent with a mechanism whereby microtubules deliver localized doses of relaxing signals to contact sites to retard or reverse their development. We propose that it is via this route that microtubules exert their well-established control on cell polarity.     

Evolution of the Rho family of ras-like GTPases in eukaryotes

GTPases of the Rho family are molecular switches that play important roles in converting and amplifying external signals into cellular effects. Originally demonstrated to control the dynamics of the F-actin cytoskeleton, Rho GTPases have been implicated in many basic cellular processes that influence cell proliferation, differentiation, motility, adhesion, survival, or secretion. To elucidate the evolutionary history of the Rho family, we have analyzed over 20 species covering major eukaryotic clades from unicellular organisms to mammals, including platypus and opossum, and have reconstructed the ontogeny and the chronology of emergence of the different subfamilies. Our data establish that the 20 mammalian Rho members are structured into 8 subfamilies, among which Rac is the founder of the whole family. Rho, Cdc42, RhoUV, and RhoBTB subfamilies appeared before Coelomates and RhoJQ, Cdc42 isoforms, RhoDF, and Rnd emerged in chordates. In vertebrates, gene duplications and retrotranspositions increased the size of each chordate Rho subfamily, whereas RhoH, the last subfamily, arose probably by horizontal gene transfer. Rac1b, a Rac1 isoform generated by alternative splicing, emerged in amniotes, and RhoD, only in therians. Analysis of Rho mRNA expression patterns in mouse tissues shows that recent subfamilies have tissue-specific and low-level expression that supports their implication only in narrow time windows or in differentiated metabolic functions. These findings give a comprehensive view of the evolutionary canvas of the Rho family and provide guides for future structure and evolution studies of other components of Rho signaling pathways, in particular regulators of the RhoGEF family.     

腺苷酸环化酶3缺失对小鼠主要嗅觉表皮组织内相关因子及信号通路的影响

主要嗅觉表皮(main olfactory epithelium, MOE)是哺乳动物感知气味分子的主要嗅觉器官。在MOE组织内,大多数嗅觉神经元通过cAMP信号传导通路感知气味信息。作为嗅觉cAMP信号通路的主要成员之一,腺苷酸环化酶3（adenylyl cyclase 3, ac3）基因敲除小鼠嗅觉探测功能丧失。除cAMP信号传导通路外,MOE内AC3相关因子AC2和AC4,以及肌醇1,4,5-三磷酸（inositol 1,4,5-trisphosphate,IP3）信号通路和Sonic Hedgehog（Shh）信号通路均有表达。然而,敲除ac3是否会对ac2和ac4以及IP3和Shh信号通路成员产生影响,尚不清楚。本文以AC3缺失（AC3-/-）及其野生型小鼠（AC3+/+）MOE为材料,采用实时荧光定量PCR（qRT-PCR）和免疫荧光组织化学方法,发现AC3缺失后,MOE内的ac2和ac4,以及IP3信号通路中的IP3受体ip3r1及钙调蛋白calm1和calm2表达水平均明显降低。Shh信号通路中的受体patched(ptch)与smoothened(smo)、以及核转录因子gli1与gli2的表达也受到了影响。总之,AC3基因缺失不但导致小鼠MOE组织中cAMP信号通路受损,同时AC3相关因子,IP3信号通路和Shh信号通路的传导也受到抑制。本文对于阐明AC3基因敲除小鼠嗅觉丧失的原因及其嗅觉探测机制具有重要启示作用。     

神经炎症及其体外模型

神经炎症是一种累及神经系统的炎症性疾病,通常表现为神经组织的异常反应或损伤,伴随着免疫系统的参与。小胶质细胞和星形胶质细胞作为中枢神经系统重要免疫细胞和支撑细胞,具有识别危险信号、产生炎症介质、清除病原微生物等功能,在维持稳态和调控神经炎症发生发展中发挥关键作用。神经炎症可以影响中枢神经系统或周围神经系统,参与多种神经系统疾病的发生发展。本文简述了神经炎症的相关通路研究现状,并介绍了目前常用的神经炎症细胞研究模型,为深入了解神经炎症发生的分子机制和预防治疗药物的筛选提供参考。     

参与细胞衰老的蛋白质结构域

  大多数正常体细胞有有限的复制周期,并最终进入生长停滞状态被称为复制性衰老.迄今比较公认的3条细胞衰老信号转导途径是：p16INK4a/Rb、p19ARF/p53/p21Waf1以及PTEN/p27.目前发现,在基因转录水平上,有些转录因子的结构域对调节p16INK4a、p53/p21Waf1以及p27等与细胞衰老相关基因的表达有重要作用,如E2DBD、环指域(RING finger)等;其次,各条通路要发挥作用,必然要借助其上下游蛋白质的相互作用,其中结构域发挥了纽带作用.本文对其中某些蛋白质相互作用的结构域进行了描述.最后,还总结了其他一些参与细胞衰老的结构域.