猪中性粒细胞磷酸二酯酶基因表达及活性研究

 【目的】通过对猪中性粒细胞磷酸二酯酶（PDE）基因表达、活性及特异性抑制剂实验检测，研究其存在的主要PDE亚型及在体外的活性，为探讨PDE在中性粒细胞的分布、活性变化及对cAMP、cGMP调节与中性粒细胞功能关系提供依据。【方法】采用反转录聚合酶链反应（RT-PCR）检测PDE基因在猪中性粒细胞的表达，以高效液相色谱（HPLC）检测环核苷酸在PDE反应前后的含量变化，计算PDE活性。【结果】在检测的18个PDE亚型中，PDE1B、2A、3A、3B、4A、4B、4C、4D、5A、7A、7B、8A、8B、9A、11A 共15个PDE mRNA在猪中性粒细胞表达，特异性抑制剂实验表明PDE4、PDE5分别为水解cAMP、cGMP的主要PDE亚型；cAMP/cGMP-PDE在10～40 μl范围内，与其活性存在良好的线性关系（r＝0.9929/0.9992）。【结论】猪中性粒细胞至少存在15个PDE亚型，其中PDE4、PDE5为主要存在的2个亚型，PDE样品量在一定范围内与其活性存在良好的线性关系，可作为筛选PDE型中性粒细胞功能调节剂的方法。     

Influence of gallic acid on porcine neutrophils phosphodiesterase 4, IL-6, TNF-α and rat arthritis model

Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inhibition on cAMP-phosphodiesterase (PDE). To explore the anti-inflammatory effect and mechanism, the influence of gallic acid on neutrophils PDE4 activity and expression, TNF-α and IL-6 content and rat arthritis model were further studied. PDE4 activity and gene express were calculated respectively by substrate cAMP change examined with HPLC and real-time RT-PCR. The concentration of IL-6 and TNF-α in supernatant were assayed by ELISA method. Model of rat arthritis was caused by complete Freund’s adjuvant. Results showed that gallic acid had a dose-dependent restraint on PDE4 activity of neutrophils in vitro, promoted significantly PDE4A expression (P<0.01), and had no influence on the expressions of PDE4B and 4D. However, PDE4C expression was not detected. Gallic acid could promote IL-6 release (P<0.05), and inhibit TNF-α release of neutrophils (P<0.05). The experiment in vivo showed that gallic acid had obvious restraint on local inflammation of animal model (P<0.05). Therefore, the anti-inflammatory effect of gallic acid may be mediated in part through an inhibition on PDE4 activity and further an increase of IL-6 and a decrease of TNF-α of neutrophils, and this effect seemed to have no relationship with PDE4 expression.     

犬中枢神经不同部位磷酸二酯酶基因表达和活性测定

为探明磷酸二酯酶(phosphodiesterase,PDE)在犬中枢神经活动中的作用,采用反转录聚合酶链反应检测18个PDE亚型在犬中枢神经不同部位中(大脑、小脑、延髓和脊髓各段)的表达分布,以高效液相色谱法检测环核苷酸在酶反应前后的含量变化,计算PDE活性。结果显示:在所测18个PDE亚型中,犬中枢神经的8个测定部位均有PDE1A,PDE1B,PDE1C,PDE2A,PDE3A,PDE3B,PDE4A,PDE4B,PDE4C,PDE4D,PDE5A,PDE7A,PDE7B,PDE8A,PDE8B,PDE9A,PDE11A表达,PDE10A均呈阴性表达,不同部位之间表达量差异较大,其中PDE4在各部位均呈优势表达;8个测定部位cAMP-PDE活性均高于cGMP-PDE活性,且不同部位PDE活性存在差异,其中脑组织cAMP-PDE活性和cGMP-PDE活性均高于脊髓各段。结果提示PDE可能在由cAMP和cGMP介导的中枢神经经信号传导中发挥着重要作用。     

Luteolin prevents f MLP-induced neutrophils adhesion via suppression of LFA-1 and phosphodiesterase 4 activity

Luteolin is an active ingredient found early from Folium perillae and Flos lonicerae, and has a specific inhibition on phosphodiesterase 4(PDE4) activity in vitro. Researches show luteolin has pharmacological effects of anti-inflammation, anti-anaphylaxis, antitumor, antioxidant, protection of nervous system and so on, and has mainly been used for the treatment of respiratory inflammatory diseases, cancer and cardiovascular disease in clinic. PDE4, specific to hydrolyze cyclic AMP(c AMP), is considered to be a new anti-inflammatory target due to the decisive role on c AMP signal in inflammatory cells such as neutrophils. In order to explore the anti-inflammatory mechanism, we further studied the effects of luteolin on the activity and expression of PDE4, the expression of lymphocyte function-associated antigen-1(LFA-1) and macrophage-1(MAC-1) in neutrophils, and the adhesion of neutrophils and endothelial cells. The results showed that luteolin had a dose-dependent inhibition on both bare PDE4 activity and PDE4 in cultured neutrophils, and had an obviously promotive effect on gene expressions of PDE4 A, 4B and 4D in later period. Luteolin had a significant inhibitory effect on neutrophils adhesion and LFA-1 expression in early stage, and had no obvious effect on MAC-1 expression. Therefore, luteolin can inhibit LFA-1 expression of neutrophils, then inhibit the adhesion of neutrophils and endothelial cells, and the mechanism is at least related with the inhibition of PDE4 activity.     

中草药对磷酸二酯酶4活性影响的初步研究

以对磷酸二酯酶4(PDE4)活性的影响为指标,筛选PDE4选择性中草药调节剂,为中兽医药理学研究和临床调节环核苷酸水平提供依据。以cAMP为底物,加入由猪嗜中性粒细胞中提取的PDE4与中草药样品, 用HPLC法检测反应后的cAMP含量,计算中草药对酶活性的影响,正数为抑制作用,负数为促进作用。54味中草药里,对PDE4活性具有抑制作用的有38味,具有促进作用的有16味。部分所选中草药对PDE4活性具有较强的抑制作用,部分具有较强的促进作用,提示从中草药里筛选特异性PDE4活性调节剂是可行的。     

牛蒡子苷对小鼠原代骨骼肌细胞磷酸二酯酶活性及细胞生长的影响

 【目的】以茶碱为参照,观察中药成分牛蒡子苷对原代骨骼肌细胞磷酸二酯酶（Phosphodiesterase,PDE）活性及蛋白质合成的影响,探讨中药通过抑制PDE促进肌肉生长的作用及机理。【方法】分离1～3日龄ICR小鼠四肢肌肉用于骨骼肌原代细胞培养,在培养至第5～6天时向培养基中添加不同浓度的牛蒡子苷和茶碱,以不含牛蒡子苷和茶碱的培养基为阴性对照,继续培养24 h,采用HPLC、ELISA以及考马斯亮蓝法分别测定骨骼肌细胞cAMP PDE的活性、细胞内cAMP水平以及细胞总蛋白质合成。【结果】牛蒡子苷终浓度达到2.5 μg•ml-1、茶碱终浓度为20 μg•ml-1时均能极显著抑制原代培养骨骼肌细胞cAMP PDE的活性(P＜0.01）,显著提高细胞内cAMP水平（P＜0.05）,极显著促进肌细胞总蛋白质的合成（P＜0.01）。【结论】中药成分牛蒡子苷具有通过调节骨骼肌细胞内PDE的活性和cAMP水平,增加肌细胞蛋白质合成,促进骨骼肌细胞生长的作用。结果提示对PDE有抑制作用的中药有望成为促进动物生长的新型饲料添加剂。     

玉米大斑病菌环腺苷酸磷酸二酯酶基因克隆及表达分析

【目的】获得玉米大斑病菌(Setosphaeria turcica)环腺苷酸磷酸二酯酶(c AMP phosphodiesterase,PDE)基因,并分析其在病菌侵染结构发育过程及侵染寄主早期阶段中的表达,为深入探索c AMP信号途径调控病菌致病性的作用机制打下基础。【方法】根据酿酒酵母(Saccharomyces cerevisiae)、白色念珠菌(Candida albicans)、灰霉病菌(Botrytis cinerea)、稻瘟病菌(Magnaporthe oryzae)、绿僵菌(Metarhizium anisopliae)和黑曲霉(Aspergillus niger)6种真菌PDE基因的保守序列,利用简并引物PCR对基因保守片段进行扩增,结合RACE和Genome Walking技术获得基因全长及其侧翼序列;利用MEGA 5.0软件对PDE蛋白预测编码产物进行多重序列比对,并采用邻近法构建系统发育树;利用GSDS分析基因结构,Prot Param分析理化性质,SOMPA预测二级结构,SMART数据库在线分析保守结构域;收集人造疏水介质诱导下侵染结构发育不同时期以及侵染感病寄主叶片不同时间的玉米大斑病菌材料,利用q RT-PCR技术研究StPDE在病菌侵染结构形成过程中不同阶段的转录水平。【结果】玉米大斑病菌基因组中存在1个高亲和力磷酸二酯酶基因(StH-PDE)和1个低亲和力磷酸二酯酶基因(StL-PDE)。其中,StH-PDE全长3 208 bp,包含5个内含子和6个外显子,ORF为2 898 bp。StL-PDE全长5054 bp,包含4个内含子和5个外显子,ORF为3 090 bp。StH-PDE和StL-PDE分别含有保守的Ⅰ型和Ⅱ型c AMP磷酸二酯酶催化结构域。不同的植物病原真菌中PDE同源基因分别呈现出高度的相似性,其中,StH-PDE与Magnaporthe grisea、Cordyceps militaris、Metarhizium acridum等病原真菌的高亲和力磷酸二酯酶基因聚于同一进化支,StL-PDE与Ascochyta rabiri、Scedosporium apiospermum、Fusarium oxysporum、Metarhizium album等病原真菌的低亲和力磷酸二酯酶基因聚于相同进化支。人造疏水介质诱导下,与菌丝相比,StH-PDE和StL-PDE在分生孢子中的表达水平均显著上调,其中StH-PDE和StL-PDE分别上调了约2倍和52倍。孢子萌发初期两个基因表达水平显著下调,随着萌发的进行,表达水平缓慢回升,至附着胞形成阶段,基因表达出现了第2次高峰,随后表达水平再次下调。在整个过程中,StH-PDE的最高表达水平则出现在附着胞形成时期,达到了菌丝体中的近7倍、分生孢子中的近2倍,而StL-PDE的表达水平始终低于其在分生孢子中的表达水平。StH-PDE和StL-PDE在病菌侵染寄主过程中的表达水平变化趋势与其在人工疏水介质诱导下的表现基本一致。在孢子萌发早期表达显著下调,随着时间延长,缓慢回升,至接种后18和24 h StH-PDE表达水平上调,超过萌发初期。【结论】在病菌侵染结构发育过程中,StH-PDE和StL-PDE均呈现下调-上调-下调的表达水平变化趋势。StH-PDE在附着胞时期表达水平最高,StL-PDE在分生孢子中的相对表达水平最高。     

猪嗜中性粒细胞cAMP磷酸二酯酶的提取与活性检测

目的:提取动物体的cAMP磷酸二酯酶(PDE),并检测其活性,为兽医临床研究PDE活性的生理病理变化和中西药物对PDE活性调节作用建立实验方法。方法:猪血经过葡聚糖沉降,淋巴细胞分离液分离,特殊分离液洗涤和红细胞溶胀后,获得嗜中性白细胞。嗜中性白细胞破碎后释放PDE,通过反相高效液相色谱(RP HPLC)法测定反应体系中cAMP的含量,根据底物(cAMP)的减少量,确定嗜中性白细胞中PDE活性。结果:经显微镜计数嗜中性粒细胞纯度达95%;酶量在10～40μl间对cAMP的分解率为9 90%～31 39%,与PDE活性之间存在直线相关关系(r=0 99)。结论:猪嗜中性粒细胞中含有高纯度、高活性的cAMP PDE;高效液相色谱法可以准确测定PDE反应前后cAMP含量的变化;两种方法结合可以作为兽医临床研究机体PDE活性变化和中西药物对PDE活性调节作用的新方法。     

牛蒡子与牛蒡子苷对小鼠骨骼肌cAMP及其磷酸二酯酶活性和生长性能的影响

 【目的】观察中药牛蒡子及其主要成分牛蒡子苷对小鼠骨骼肌cAMP磷酸二酯酶(cAMP PDE)活性和cAMP含量、血浆cAMP含量与生长性能的影响,探讨促进动物生长的作用及机理。【方法】断奶ICR小鼠分别灌服不同剂量的牛蒡子煎剂：1.00、0.50、0.25 g/只,牛蒡子苷溶液：1.50、0.75、0.38 mg/只和阳性对照茶碱溶液：0.75、0.38、0.19 mg/只。记录体重和采食量,采用HPLC和ELISA法分别测定骨骼肌组织cAMP PDE活性和血浆cAMP含量。【结果】1.00 g和0.50 g的牛蒡子煎剂和3个剂量的牛蒡子苷显著或极显著降低采食量;除0.38 mg的牛蒡子苷外,各剂量给药组都显著或极显著促进增重;各剂量的牛蒡子、牛蒡子苷和茶碱都极显著提高饲料转化率(P＜0.05,P＜0.01,或P＜0.001)。各剂量的牛蒡子、牛蒡子苷和茶碱都显著或极显著抑制cAMP PDE活性;除1.5 mg的牛蒡子苷外,都显著或极显著提高骨骼肌组织cAMP含量,除0.75 mg茶碱外,都显著或极显著提高血浆cAMP含量(P＜0.05,P＜0.01,或P＜0.001)。骨骼肌cAMP含量与cAMP PDE活性呈极显著负相关,r = -0.402(P＜0.001),血浆cAMP含量与骨骼肌cAMP含量呈极显著正相关性,r =0.553(P＜0.001),与cAMP PDE活性呈负相关,r =-0.436(P＞0.05)。【结论】牛蒡子和牛蒡子苷通过抑制骨骼肌cAMP PDE活性,提高骨骼肌和血浆cAMP水平,提高动物生长性能。     

Targeting of cyclic AMP degradation to beta 2-adrenergic receptors by beta-arrestins

Catecholamines signal through the beta2-adrenergic receptor by promoting production of the second messenger adenosine 3',5'-monophosphate (cAMP). The magnitude of this signal is restricted by desensitization of the receptors through their binding to beta-arrestins and by cAMP degradation by phosphodiesterase (PDE) enzymes. We show that beta-arrestins coordinate both processes by recruiting PDEs to activated beta2-adrenergic receptors in the plasma membrane of mammalian cells. In doing so, the beta-arrestins limit activation of membrane-associated cAMP-activated protein kinase by simultaneously slowing the rate of cAMP production through receptor desensitization and increasing the rate of its degradation at the membrane.     

A functional link between RuBisCO-like protein of Bacillus and photosynthetic RuBisCO

The genomes of several nonphotosynthetic bacteria, such as Bacillus subtilis, and some Archaea include genes for proteins with sequence homology to the large subunit of ribulose bisphosphate carboxylase/oxygenase (RuBisCO). We found that such a RuBisCO-like protein (RLP) from B. subtilis catalyzed the 2,3-diketo-5-methylthiopentyl-1-phosphate enolase reaction in the methionine salvage pathway. A growth-defective mutant, in which the gene for this RLP had been disrupted, was rescued by the gene for RuBisCOfrom the photosynthetic bacterium Rhodospirillum rubrum. Thus, the photosynthetic RuBisCO from R. rubrum retains the ability to function in the methionine salvage pathway in B. subtilis.     

槲皮素对肉鸡脂肪细胞环腺苷酸信号通路的作用

【目的】研究槲皮素对肉鸡脂肪细胞甘油三酯沉积过程中环腺苷酸（cyclic adenosine monophosphate,cAMP）信号通路的作用。【方法】将脂肪细胞随机分5组,每组6个重复;空白对照组为基础培养液,溶剂对照组为含2‰二甲基亚砜（DMSO）的培养液,试验组为含10、20和40 mg•L-1槲皮素的培养液,分别于24、48和72 h收集细胞及培养液;ELISA法测定乙酰CoA羧化酶（acetyl CoA carboxylase,ACC）、脂肪酸合成酶（fatty acid synthase,FAS）、脂蛋白脂酶（lipoprotein lipase,LPL）、cAMP、腺苷酸环化酶（adenylate cyclase,AC）、磷酸二脂酶（phosphodiesterase,PDE）、蛋白激酶（protein kinase A,PKA）含量;紫外分光光度计测定甘油三酯（triacylglycerides,TG）含量。【结果】与空白对照组相比,①溶剂对照组各指标均无显著差异（P＞0.05）;②20和40 mg•L-1槲皮素组ACC、FAS、LPL、TG和PDE含量显著降低（P＜0.05）,cAMP和PKA含量显著增加（P＜0.05）;③3个槲皮素组AC含量均无显著差异（P＞0.05）。【结论】一定剂量槲皮素可通过调控cAMP信号通路抑制脂肪合成,并减少脂肪沉积。     

Structure and allostery of the PKA RIIβ tetrameric holoenzyme

In its physiological state, cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) is a tetramer that contains a regulatory (R) subunit dimer and two catalytic (C) subunits. We describe here the 2.3 angstrom structure of full-length tetrameric RIIβ(2):C(2) holoenzyme. This structure showing a dimer of dimers provides a mechanistic understanding of allosteric activation by cAMP. The heterodimers are anchored together by an interface created by the β4-β5 loop in the RIIβ subunit, which docks onto the carboxyl-terminal tail of the adjacent C subunit, thereby forcing the C subunit into a fully closed conformation in the absence of nucleotide. Diffusion of magnesium adenosine triphosphate (ATP) into these crystals trapped not ATP, but the reaction products, adenosine diphosphate and the phosphorylated RIIβ subunit. This complex has implications for the dissociation-reassociation cycling of PKA. The quaternary structure of the RIIβ tetramer differs appreciably from our model of the RIα tetramer, confirming the small-angle x-ray scattering prediction that the structures of each PKA tetramer are different.     

Limb and skin abnormalities in mice lacking IKKalpha

The gene encoding inhibitor of kappa B (IkappaB) kinase alpha (IKKalpha; also called IKK1) was disrupted by gene targeting. IKKalpha-deficient mice died perinatally. In IKKalpha-deficient fetuses, limb outgrowth was severely impaired despite unaffected skeletal development. The epidermal cells in IKKalpha-deficient fetuses were highly proliferative with dysregulated epidermal differentiation. In the basal layer, degradation of IkappaB and nuclear localization of nuclear factor kappa B (NF-kappaB) were not observed. Thus, IKKalpha is essential for NF-kappaB activation in the limb and skin during embryogenesis. In contrast, there was no impairment of NF-kappaB activation induced by either interleukin-1 or tumor necrosis factor-alpha in IKKalpha-deficient embryonic fibroblasts and thymocytes, indicating that IKKalpha is not essential for cytokine-induced activation of NF-kappaB.     

Diverse psychotomimetics act through a common signaling pathway

Three distinct classes of drugs: dopaminergic agonists (such as D-amphetamine), serotonergic agonists (such as LSD), and glutamatergic antagonists (such as PCP) all induce psychotomimetic states in experimental animals that closely resemble schizophrenia symptoms in humans. Here we implicate a common signaling pathway in mediating these effects. In this pathway, dopamine- and an adenosine 3',5'-monophosphate (cAMP)-regulated phospho-protein of 32 kilodaltons (DARPP-32) is phosphorylated or dephosphorylated at three sites, in a pattern predicted to cause a synergistic inhibition of protein phosphatase-1 and concomitant regulation of its downstream effector proteins glycogen synthesis kinase-3 (GSK-3), cAMP response element-binding protein (CREB), and c-Fos. In mice with a genetic deletion of DARPP-32 or with point mutations in phosphorylation sites of DARPP-32, the effects of D-amphetamine, LSD, and PCP on two behavioral parameters-sensorimotor gating and repetitive movements-were strongly attenuated.     

猪磷酸二酯酶7A mRNA荧光定量PCR检测方法的建立与初步应用

为研究磷酸二酯酶(PDE)7A基因在猪体内的分布,本试验通过构建含有目的基因片段标准质粒的方法,成功建立荧光定量PCR检测PDE7A基因的标准曲线,可检测到最低1×102copies/μL的初始模板量,重复试验变异系数为2.22%～3.71%,具有较高的灵敏度和可重复性。用该方法检测到PDE7AmRNA在试验用小型猪的心肌中表达量最高(比率为4.54×10-2),骨骼肌次之(1.44×10-2),其他内脏器官较少。     

Role of adaptor TRIF in the MyD88-independent toll-like receptor signaling pathway

Stimulation of Toll-like receptors (TLRs) triggers activation of a common MyD88-dependent signaling pathway as well as a MyD88-independent pathway that is unique to TLR3 and TLR4 signaling pathways leading to interferon (IFN)-beta production. Here we disrupted the gene encoding a Toll/IL-1 receptor (TIR) domain-containing adaptor, TRIF. TRIF-deficient mice were defective in both TLR3- and TLR4-mediated expression of IFN-beta and activation of IRF-3. Furthermore, inflammatory cytokine production in response to the TLR4 ligand, but not to other TLR ligands, was severely impaired in TRIF-deficient macrophages. Mice deficient in both MyD88 and TRIF showed complete loss of nuclear factor kappa B activation in response to TLR4 stimulation. These findings demonstrate that TRIF is essential for TLR3- and TLR4-mediated signaling pathways facilitating mammalian antiviral host defense.     

Structure of MyTH4-FERM domains in myosin VIIa tail bound to cargo

The unconventional myosin VIIa (MYO7A) is one of the five proteins that form a network of complexes involved in formation of stereocilia. Defects in these proteins cause syndromic deaf-blindness in humans [Usher syndrome I (USH1)]. Many disease-causing mutations occur in myosin tail homology 4-protein 4.1, ezrin, radixin, moesin (MyTH4-FERM) domains in the myosin tail that binds to another USH1 protein, Sans. We report the crystal structure of MYO7A MyTH4-FERM domains in complex with the central domain (CEN) of Sans at 2.8 angstrom resolution. The MyTH4 and FERM domains form an integral structural and functional supramodule binding to two highly conserved segments (CEN1 and 2) of Sans. The MyTH4-FERM/CEN complex structure provides mechanistic explanations for known deafness-causing mutations in MYO7A MyTH4-FERM. The structure will also facilitate mechanistic and functional studies of MyTH4-FERM domains in other myosins.     

Rapamycin-induced insulin resistance is mediated by mTORC2 loss and uncoupled from longevity

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.     

Rare structural variants disrupt multiple genes in neurodevelopmental pathways in schizophrenia

Schizophrenia is a devastating neurodevelopmental disorder whose genetic influences remain elusive. We hypothesize that individually rare structural variants contribute to the illness. Microdeletions and microduplications >100 kilobases were identified by microarray comparative genomic hybridization of genomic DNA from 150 individuals with schizophrenia and 268 ancestry-matched controls. All variants were validated by high-resolution platforms. Novel deletions and duplications of genes were present in 5% of controls versus 15% of cases and 20% of young-onset cases, both highly significant differences. The association was independently replicated in patients with childhood-onset schizophrenia as compared with their parents. Mutations in cases disrupted genes disproportionately from signaling networks controlling neurodevelopment, including neuregulin and glutamate pathways. These results suggest that multiple, individually rare mutations altering genes in neurodevelopmental pathways contribute to schizophrenia.