核因子kB在糖尿病大鼠肺组织活性的变化

目的观测糖尿病大鼠肺组织的病理改变及蛋白激酶C、核转录因子κB(NFκB)活性的变化,探讨NFκB在糖尿病大鼠肺病变中作用。方法制作糖尿病大鼠模型、4w后观察其肺部组织病理改变,采用改良的Takay法测定PKC活性,蛋白质免疫印迹分析及免疫组化方法检测NFκB在糖尿病大鼠肺组织表达变化。结果DM大鼠4w后毛细血管壁及肺泡间隔增厚,肺间质胶原成份增多,肺组织NFκBWestern带平均灰度值为(72.17±3.12)。肺组织PKC含量与对照组相比,细胞浆升高41%,细胞膜升高75.9%,表现出膜移位现象。结论糖尿病大鼠肺组织高糖环境下信号传导系统PKCNFκB被激活,可能与糖尿病肺部并发症的发生和发展相关。     

核因子κB在糖尿病大鼠肺组织活性的变化

目的观测糖尿病大鼠肺组织的病理改变及蛋白激酶C、核转录因子-κB(NF-κB)活性的变化,探讨NF-κB在糖尿病大鼠肺病变中作用.方法制作糖尿病大鼠模型、4 w后观察其肺部组织病理改变,采用改良的Takay法测定PKC活性,蛋白质免疫印迹分析及免疫组化方法检测NF-κB在糖尿病大鼠肺组织表达变化.结果 DM大鼠4 w后毛细血管壁及肺泡间隔增厚,肺间质胶原成份增多,肺组织NF-κB Western带平均灰度值为(72.17±3.12).肺组织PKC含量与对照组相比,细胞浆升高41%,细胞膜升高75.9%,表现出膜移位现象.结论糖尿病大鼠肺组织高糖环境下信号传导系统PKC-NF-κB被激活,可能与糖尿病肺部并发症的发生和发展相关.     

槲皮素对糖尿病大鼠肾脏的保护作用

目的探讨槲皮素对糖尿病大鼠肾脏保护作用.方法对链脲佐菌素诱导糖尿病大鼠动物模型,给予槲皮素100mg*kg-1*d-1,治疗共8周.放免法测定尿白蛋白排泄率,测定内生肌酐清除率及肾小球蛋白激酶C活力.RT-PCR检测方法观察槲皮素对糖尿病大鼠肾脏皮质TGF-β1基因表达的影响,观察槲皮素对肾小球形态及病理改变.结果糖尿病大鼠存在肾小球高滤过,尿白蛋白排泄率、肾重/体重、肾小球细胞膜蛋白激酶C活力明显升高.肾脏皮质TGF-β1基因表达显著增加,肾小球肥大.给予槲皮素治疗2周及8周时,糖尿病大鼠肾小球滤过率、尿白蛋白排泄率、肾小球肥大均较糖尿病未治疗组显著降低,肾小球细胞膜蛋白激酶C活力及TGF-β1基因表达显著下降.肾脏病理改变不显著.结论槲皮素通过抑制糖尿病大鼠肾脏蛋白激酶C活力可以纠正糖尿病早期肾脏高滤过、高灌注,并同抑制肾脏皮质TGF-β1基因过度表达有关,抑制蛋白激酶C活性对防治糖尿病肾病尤为重要.     

D-α-生育酚调节蛋白激酶C活性对糖尿病视网膜病变的影响

目的　探讨蛋白激酶C(PKC)在糖尿病视网膜病变 (DR)中的作用和D α 生育酚对糖尿病视网膜毛细血管组织病理的影响。方法　实验大鼠分为 4组 :正常对照组 (C组 )、D α 生育酚处理的正常对照组 (T组 )、糖尿病组 (D组 )、D α 生育酚处理病鼠组 (DT组 )。血糖、HbA1c和D α 生育酚含量以及原位PKC、ATPase活性在处理后 6个月被检测 ,毛细血管床形态立体定量评估DR。结果病程 6个月时 ,D组大鼠深、浅层毛细血管呈现周细胞减少、基底膜增厚的特征性改变 ,成模 6个月后糖尿病大鼠视网膜PKC活性显著增高 >10 0 % ,D α 生育酚可阻止此升高。同一大鼠视网膜 ,D α 生育酚也可阻止糖尿病诱导的Na+ K+ ATPase和Ca2 + ATPase活力下降。D α 生育酚可显著改善糖尿病视网膜微血管周、内皮细胞截面积和深浅层毛细血管基底膜厚度 ,而对血糖、HbA1c无影响。结论糖尿病诱导的组织病理异常可能大部分由PKC介导 ,D α 生育酚可改善糖尿病视网膜毛细血管超微结构     

蛋白激酶C和TGF-β1在糖尿病大鼠肾脏中的表达

目的研究糖尿病大鼠肾小球中蛋白激酶C（PKC）活性变化和转化生长因子-β1（TGF-β1）的动态变化，探讨二者之间相互关系及其与糖尿病肾病（DN）发生发展的关系。方法用链脲佐菌素制备糖尿病大鼠实验模型，将大鼠随机分为正常对照组（N）、糖碌病2w组（DM2）和糖尿病4w组（DM4）。断头处死，分离肾小球，提取纯化胞浆及胞膜蛋白，利用（γ-32^P）-ATP底物磷酸化的方法检测胞浆及胞膜PKC括性。用免疫组织化学和400倍光镜检测TGF-β1在各组大鼠肾脏的表达。结果（1）糖尿病大鼠肾小球细胞内总的PKC活性与对照组无显著性差异，胞浆PKC活性略有下降，相差不显著；肾小球细胞膜PKC活性明显高于正常对照组，膜结合PKC百分比显著增加，且细胞膜PKC活性与肾脏肥大指数及Cer呈正相关。（2）糖尿病组TGF-β1的表达多于正常组。（3）肾小球细胞膜PKC活性与TGF-β1的表达正相关。结论高血糖慢性刺激可引起肾小球PKC活性增高，并诱导TGF-β1的表达。在糖尿病早期肾内血流动力学改变中发挥着重要的调控作用。     

细胞间相互作用和糖尿病视网膜病变

糖尿病视网膜病变是糖尿病最常见和最严重的并发症之一，已成为致盲的最重要的原因。糖尿病视网膜病变发生、发展的确切机制目前尚不十分清楚，但与多元醇通路的激活，蛋白质非酶糖基化，自由基活性增强，蛋白激酶C活化，生长因子失衡，氨基已糖通路活性提高及血流动力学改变等均密切相关。其病理组织改变包括：①毛细血管改变，毛细血管主要病理改变有三，即周细胞减少；     

吡格列酮对糖尿病大鼠肺组织TNF-α和NF-κB的影响

目的 探讨过氧化物酶体增殖物激活受体(PPAR)-γ激动剂吡格列酮对糖尿病大鼠肺部损害的保护作用及其机制.方法 腹腔注射链脲佐菌素(55 mg/kg)制成糖尿病动物模型.48只健康SD雄性大鼠随机分为4组:对照组、糖尿病组、高、低剂量吡格列酮治疗组.8 w后检测存活大鼠肺组织肿瘤坏死因子(TNF)-α水平,取右肺组织,观察病理改变,并检测核因子(NF)-κB活性表达的变化.结果 糖尿病组大鼠肺组织TNF-α的水平和NF-κB活性较对照组显著增高(P＜0.05).给予吡格列酮处理8 w后,肺组织TNF-α的水平和NF-κB活性明显降低(P＜0.05).结论 PPAR-γ激动剂吡格列酮可有效减轻糖尿病大鼠肺部损害,其机制可能与抑制NF-κB过度活化和TNF-α的水平有关.     

阻断肾素-血管紧张素系统对糖尿病大鼠肾脏蛋白激酶C活性的影响

目的　观察阻断肾素 血管紧张素系统对糖尿病大鼠肾组织蛋白激酶C(PKC)活性的影响。方法　以链脲佐菌素造成大鼠糖尿病模型。未给予链脲佐菌素的大鼠作为正常对照组 (A组 ) ,糖尿病大鼠分为未处理组 (B组 )、福辛普利治疗组 (C组 )、洛沙坦治疗组 (D组 )和福辛普利 洛沙坦联合治疗组 (E组 )。 2 4周后测血糖、HbA1c、肾重 /体重、尿蛋白排泄率 (UPER)及肾组织PKC活性。结果　 ( 1)B组的肾重 /体重和UPER显著高于其余各组 ,C组和D组之间差异无显著性 ,E组较C组和D组更低 (P <0 .0 5 )。 ( 2 )B组肾组织膜PKC活性显著高于A组 (P <0 .0 0 1)、C组、D组和E组 (P <0 .0 1) ;B组胞液PKC活性显著低于A组(P <0 .0 1)、C组、D组和E组 (P <0 .0 5 ) ;B组胞液和膜PKC活性比显著低于A组 (P <0 .0 0 1)、C组、D组和E组 (P <0 .0 1)。C组和D组胞液PKC活性、膜PKC活性及二者之比差异无显著性 ,但E组的变化较C组和D组更为显著 (P <0 .0 5 )。结论　 ( 1)血管紧张素转化酶抑制剂 (ACEI)和血管紧张素Ⅱ受体拮抗剂(ARB)均能减轻糖尿病大鼠的肾脏肥大 ,减少UPER。 ( 2 )长期高糖可引起大鼠肾脏PKC活性异常升高并诱导胞液PKC向细胞膜转位。 ( 3 )ACEI和ARB均可抑制糖尿病大鼠肾脏PKC活性的升高及转位 ,二者的作用相当 ,联合     

初发糖尿病大鼠肾小球蛋白激酶C活性变化的研究

目的：检测初发糖尿病大鼠肾小球蛋白激酶Ｃ（ＰＫＣ）活性变化,以推断ＰＫＣ活性变化在肾内血流动力学改变中所起的作用。方法：用链脲菌素制备糖尿病大鼠实验模型,在糖尿病发病２周后,分离肾小球,提取纯化胞浆及胞膜蛋白,利用γ－＾３２ＰＡＴＰ底物磷酸化的方法检测胞浆及胞膜ＰＫＣ活性。同时测量血、尿肌酐,计算内生肌酐清除率。结果：糖尿病大鼠表现出明显的肾小球高滤过及肾脏肥大现象,此时细胞内总的ＰＫＣ活性与对照     

右美托咪啶对大鼠肺IRI中p38MAPK信号通路及肺组织HMGB1表达的影响

目的研究右美托咪啶对大鼠肺缺血再灌注损伤(IRI)中p38丝裂素活化蛋白激酶(p38MAPK)及肺组织高迁移率族盒蛋白1(HMGB1)表达的影响,为分析右美托咪啶的肺保护作用奠定基础。方法将36只SD大鼠随机分为三组各12只:A组行假手术处理;B组建立大鼠急性肺IRI模型;C组在造模前以盐酸右美托咪啶预处理。手术3h后处死,取肺组织病理染色后观察组织病理学变化、行酶联免疫吸附试验检测肺组织髓过氧化酶(MPO)活性、行Western Blotting法检测肺组织磷酸化p38MAPK蛋白及HMGB1蛋白的表达。结果与A组比较,B组肺组织出现明显病理学改变,MPO活性明显更强,磷酸化p38MAPK蛋白及HMGB1蛋白表达水平亦明显增加,上述差异均有统计学意义(P0.05);与B组相比,C组上述各指标均明显下降,差异亦有统计学意义(P0.05)。磷酸化p38MAPK蛋白及HMGB1蛋白表达水平与肺组织病理损伤评分及MPO活性均呈显著正相关(P0.05)。结论肺IRI时可能出现p38MAPK信号通路异常活跃、肺组织HMGB1过表达,右美托咪啶则能有效抑制p38MAPK信号通路及肺组织HMGB1表达,这可能是其发挥肺保护作用的机制之一。     

Preferential elevation of protein kinase C isoform beta II and diacylglycerol levels in the aorta and heart of diabetic rats: differential reversibility to glycemic control by islet cell transplantation.

In the present study, we have measured protein kinase C (PKC) specific activities and total diacylglycerol (DAG) level in the aorta and heart of rats, which showed that after 2 weeks of streptozotocin (STZ)-induced diabetes, membranous PKC specific activity and total DAG content were increased significantly by 88% and 40% in the aorta and by 21% and 72% in the heart, respectively. Hyperglycemia was identified as being a causal factor since elevated glucose levels increased DAG levels in cultured aortic endothelial and smooth muscle cells. Analysis by immunoblotting revealed that only alpha and beta II PKC isoenzymes are detected in these two tissues and vascular cells among those studied. In STZ-induced diabetic rats, beta II isoenzyme is preferentially increased in both aorta and heart, whereas PKC alpha did not change significantly. The increases in membranous PKC specific activity and DAG level are observed in both spontaneous diabetes-prone diabetic BB rats as well as in STZ-induced diabetic BB and Sprague-Dawley rats, which persisted for up to 5 weeks. After 2 weeks of diabetes without treatment, the normalization of blood glucose levels for up to 3 weeks with islet cell transplants in STZ-induced diabetic BB rats reversed the biochemical changes only in the heart, but not in the aorta. These results suggest that PKC activity and DAG level may be persistently activated in the macrovascular tissues from diabetic animals and indicate a possible role for these biochemical parameters in the development of diabetic chronic vascular complications.     

PTEN在心力衰竭心肌MAPK/PKC信号通路的作用

目的 观察充血性心力衰竭病人心肌重构病理过程中肿瘤抑制因子PTEN（phosphatase and tensin homolog tumor suppressor,PTEN）及丝裂原活化蛋白激酶（mitogen-activated protein kinase,MAPK）与蛋白激酶C（protein kinase C,PKC）的作用.方法 通过手术取材,选择因瓣膜性心脏病接受二尖瓣置换术的心力衰竭病人39例,正常对照38例（其中8例来自意外伤亡的器官捐献者）.竞争蛋白结合法检测心肌组织PKC及MAPK活性,免疫沉淀法检测PTEN蛋白表达.结果 心力衰竭病人心肌组织呈典型的重构心肌的病理改变.心肌组织PTEN表达蛋白光吸收（absorbance,A）与β肌动蛋白光吸收比值（PTEN/β-actin）随心功能恶化而降低,各心力衰竭组与正常组相比,差异有统计学意义（P＜0.01）;相反,心力衰竭病人心肌组织PKC和MAPK活性明显高于对照组（P＜0.01）,并随心功能恶化其表达逐渐增加,各心力衰竭组与正常组比较,差异有统计学意义（P＜0.01）.结论 PTEN及MAPK与PKC信号通路共同参与调节CHF病人心肌重构的病理过程,PTEN在心肌重构病理过程中起负性调节作用.     

蛋白激酶C对慢性低氧大鼠肺动脉胶原表达的调控及灯盏花素的干预作用

目的　探讨蛋白激酶C(PKC)对慢性低氧大鼠肺动脉胶原表达的调控作用及灯盏花素的影响。方法　将二级Sprague Dawley(SD)大鼠分为 :对照组 (A) ,低氧组 (B) ,低氧 +灯盏花素组 (C) ,低氧时间为 4周。采用透射电镜、放射活性测定法、免疫组化、原位杂交等方法综合进行评价。结果(1)B组肺动脉平均压 (mPAP)、右心室重量比 (RV/LV +S)显著高于A组 (P <0 0 1) ,C组mPAP、RV/LV +S显著低于B组 (P <0 0 1) ;(2 )电镜显示B组肺动脉胶原纤维较A组明显为多 ,C组较B组明显为少 ;(3)B组肺组织PKC总活性 (PKCt)、胞膜PKC活性 (PKCm)、胞浆PKC活性 (PKCc)及PKCm占PKCt的百分比显著高于A组 (P <0 0 1) ,C组PKCt、PKCm、PKCc及PKCm占PKCt的百分比显著低于B组 (P <0 0 5 ) ;(4)免疫组化显示B组肺细小动脉 (直径 10 0～ 2 0 0 μm)PKC含量 (平均吸光度A值 )显著高于A组 (P <0 0 1) ,C组较B组显著为低 (P <0 0 1) ;(5 )免疫组化和原位杂交显示B组肺细小动脉 (直径约 10 0～ 2 0 0 μm)Ⅰ型胶原及Ⅰ型前胶原mRNA平均A值较A组明显为高 (P <0 0 1) ,C组较B组为低 (P <0 0 1) ,Ⅲ型胶原及Ⅲ型前胶原mRNA平均A值各组间差异无显著性 (P >0 0 5 ) ;(6 )肺组织PKC活性和肺动脉管壁PKC的表达与肺动脉管壁Ⅰ型胶原mRNA和蛋白     

The effect of acute inflammatory lung injury on the respiratory burst and protein kinase C activity of rat pulmonary alveolar macrophages

After induction of acute inflammatory lung injury in rats, unstimulated and zymosan-stimulated pulmonary alveolar macrophages (PAM) in suspension consumed significantly greater amounts of oxygen than did comparably stimulated PAM from noninjured lungs. Although oxygen consumption by PAM from injured lungs after stimulation with phorbol 12-myristate 13-acetate (PMA) was increased, it was not significantly different from that of PMA-stimulated PAM fron noninjured lungs. Despite the enhanced oxygen consumption, PAM from injured lungs in suspension did not secrete more superoxide (O2-) than did comparably stimulated PAM from noninjured lungs. It has been suggested that the respiratory burst in human polymorphonuclear leukocytes (PMN) and monocytes is dependent on the translocation of protein kinase C (PKC). We established that PKC was present in rat PAM and that acute lung injury did not alter total PKC activity or the subcellular distribution of the enzyme. Similarly, stimulation of PAM from noninjured lungs (zymosan, PMA) or injured lungs (zymosan) did not result in translocation of PKC activity, despite an enhanced oxidative burst. These results indicate that although PKC activity was present in PAM, translocation of PKC activity was not necessary for the respiratory burst.     

Fibronectin- and protein kinase C-mediated activation of ERK/MAPK are essential for proplateletlike formation

The megakaryoblastic CHRF-288 cell line was used to investigate signal transduction pathways responsible for proplateletlike formation (PPF). The role of fibronectin (FN) and protein kinase C (PKC) activation in PPF were examined. In the presence of serum and phorbol 12-myristate 13-acetate (PMA), a PKC activator, cells exhibited full megakaryocytic differentiation, manifested by adhesion, shape change, increased cell size, polyploidy, PPF, and expression of CD41(+), CD61(+), and CD62P(+). The same morphologic and phenotypic features were observed in serum-free cultures in the presence of FN/PMA. Only partial differentiation occurred when other integrin ligands were substituted for FN. FN alone induced minimal cell adhesion and spreading, while PMA alone induced only polyploidy without adhesion. Signal transduction changes involved the activation of the extracellular signal-regulated protein kinase 1 (ERK1)/ERK2 as well as c-Jun amino-terminal kinase 1 (JNK1)/stress-activated protein kinase (SAPK). Phosphoinositide-3 kinase and p38 were not stimulated under these conditions. Inhibitors were used to identify the causal relationship between signaling pathways and PPF. PD98059 and GF109203X, inhibitors of ERK1/ERK2 pathway and PKC, respectively, blocked PPF, while adhesion, spreading, and polyploidy were normal. These studies show that activation of ERK1/ERK2 mitogen-activated protein kinase pathway plays a critical role in PPF. The elucidation of the signal transduction pathway on megakaryocyte development and PPF is of crucial importance for understanding this unique biological process.     

维生素E对糖尿病大鼠肾脏的保护作用

目的探讨维生素E对糖尿病大鼠肾脏保护作用及其可能机制。方法实验动物分为正常对照组、链脲佐菌素诱导的糖尿病未治疗组、糖尿病给予维生素E（20mg.kg-1.d-1）治疗组,共观察8周。测定尿白蛋白排泄量(UAE),内生肌酐清除率（Ccr）、血浆及肾脏组织一氧化氮（NO）、一氧化氮合成酶（NOS）、内皮素（ET）和肾小球蛋白激酶C（PKC）。结果2周时糖尿病未治疗组Ccr［(6.47±1.51)ml·min-1·kg-1］、尿白蛋白排泄量［(15.60±1.64)μg/24h］、NO［(37.30±3.77)μmol/L］、NOS［(34.89±3.83)U/L］及肾小球细胞膜PKC［(86.85±11.37)pmol·min-1·mgprotein-1］明显高于对照组,ET低于对照组。8周时糖尿病大鼠肾小球细胞膜PKC［(84.18±12.14)pmol·min-1·mgprotein-1］仍明显高于对照组,但NO［(22.75±2.89)μmol/L］及NOS［(21.34±1.92)U/L］低于对照组,ET高于对照组。给予维生素E治疗组8周时,Ccr［(4.46±0.49)ml·min-1·kg-1］及尿白蛋白量［(16.31±1.12)μg/24h］显著低于未治疗组,8周时肾小球细胞膜PKC［(65.19±8.83)pmol·min-1·mgprotein-1］,2周时NO［(33.13±3.77)μmol/L］及NOS［(30.16±2.89)U/L］明显低于未治疗组,维生素E治疗组2周时与8周时的NO及NOS下降幅度明显小于未治疗组。结论维生素E通过抑制蛋白激酶C可以纠正糖尿病早期的肾脏高滤过、高灌注,并与抑制肾脏NO合成有关,抑制蛋白激酶C活性对糖尿病肾病防治尤为重要。     

Protein kinase C modulates ecdysteroidogenesis in the prothoracic gland of the tobacco hornworm, Manduca sexta

The prothoracic gland is the primary source of ecdysteroid hormones in the immature insect. Ecdysteroids coordinate gene expression necessary for growth, molting and metamorphosis. Prothoracicotropic hormone (PTTH), a brain neuropeptide, regulates ecdysteroid synthesis in the prothoracic gland. PTTH stimulates ecdysteroid synthesis through a signal transduction cascade that involves at least four protein kinases: protein kinase A (PKA), p70 S6 kinase, an unidentified tyrosine kinase, and the extracellular signal-regulated kinase (ERK). In this report, the participation of protein kinase C (PKC) in PTTH signalling is demonstrated and characterized. PTTH stimulates PKC activity through a PLC and Ca(2+)-dependent pathway that is not cAMP regulated. Inhibition of PKC inhibits PTTH-stimulated ecdysteroidogenesis as well as PTTH-stimulated phosphorylation of ERK and its upstream regulator, MAP/ERK kinase (MEK). These observations reveal that the acute regulation of prothoracic gland steroidogenesis is dependent on a web of interacting kinase pathways, which probably converge on factors that regulate translation.     

洛沙坦对蛋白激酶C在慢性缺氧大鼠模型肺动脉胶原表达作用的影响

目的　观察洛沙坦对蛋白激酶C(PKC)在慢性缺氧大鼠模型肺动脉胶原表达作用的影响。方法　将二级SD大鼠分为 3组 :A组 (正常对照组 )大鼠室内常规饲养。B组 (单纯缺氧 4周组 )大鼠置于常压低氧舱中 ,舱内充入氮气 ,使氧浓度维持在 (1 0 0± 0 5) % ,每天 8h ,每周 6d ,连续 4周 ;大鼠每天缺氧前用 2ml蒸馏水灌胃。C组 (洛沙坦干预组 )缺氧条件同B组 ,大鼠每天缺氧前用洛沙坦 (洛沙坦 50mg/kg溶于 2ml蒸馏水 )灌胃。采用透射电镜、放射活性测定法、免疫组化、原位杂交等方法观察 3组大鼠肺细小动脉超微结构、肺组织PKC活性、肺动脉管壁PKC免疫组化及Ⅰ、Ⅲ型胶原和Ⅰ、Ⅲ型前胶原基因表达的变化。结果　 (1 )B组大鼠平均肺动脉压、右心室重量比显著高于A组(P <0 0 1 ) ,C组显著低于B组 (P <0 0 1 )。 (2 )光镜下可见B组大鼠肺血管管壁厚度占血管外经的百分比、管壁面积占管总面积的百分比显著高于A组 (P <0 0 1 ) ,C组显著低于B组 (P <0 0 1 )。电镜下可见B组大鼠肺动脉胶原纤维较A组明显为多 ,C组较B组明显为少。 (3)B组大鼠肺组织细胞PKC总活性、胞膜PKC活性、胞质PKC活性及胞膜PKC活性占PKC总活性的百分比显著高于A组(P <0 0 1 ) ,C组上述指标均显著低于B组 (P <0 0 1 )。 (4)免疫组化显示 ,B     

钒酸盐纠正了糖尿病大鼠心肌组织内活化的DAG—PKC信息传导

目的 探讨糖尿病大鼠心肌细胞内传导与心功能降低的关系。方法 检测糖尿病大鼠心肌二酰基甘油含量,蛋白激酶活性和心功能变化及胃饲钒酸钠的影响。结果 糖尿病大鼠心肌ＤＡＧ含量和胞膜ＰＫＣ活性显著升高,心功能显著降低,胃饲ＳＶ后明显改善。结论ＤＡＧ－ＰＫＣ通路激活是形成糖尿病心肌病的一个重要发病机制。     

Long-Term Ethanol Exposure Impairs Neuronal Differentiation of Human Neuroblastoma Cells Involving Neurotrophin-Mediated Intracellular Signaling and in Particular Protein Kinase C

Background: Revealing the molecular changes in chronic ethanol‐impaired neuronal differentiation may be of great importance for understanding ethanol‐related pathology in embryonic development but also in the adult brain. In this study, both acute and long‐term effects of ethanol on neuronal differentiation of human neuroblastoma cells were investigated. We focused on several aspects of brain‐derived neurotrophic factor (BDNF) signaling because BDNF activates the extracellular signal‐regulated kinase (ERK) cascade, promoting neuronal differentiation including neurite outgrowth. Methods: The effects of ethanol exposure on morphological differentiation, cellular density, neuronal marker proteins, basal ERK activity, and ERK responsiveness to BDNF were measured over 2 to 4 weeks. qRT‐PCR and Western blotting were performed to investigate the expression of neurotrophin receptor tyrosin kinase B (TrkB), members of the ERK‐cascade, protein kinase C (PKC) isoforms and Raf‐Kinase‐Inhibitor‐Protein (RKIP). Results: Chronic ethanol interfered with the development of a neuronal network consisting of cell clusters and neuritic bundles. Furthermore, neuronal and synaptic markers were reduced, indicating impaired neuronal differentiation. BDNF‐mediated activation of the ERK cascade was found to be continuously impaired by ethanol. This could not be explained by expressional changes monitored for TrkB, Raf‐1, MEK, and ERK. However, BDNF also activates PKC signaling which involves RKIP, which finally leads to ERK activation as well. Therefore, we hypothesized that ethanol impairs this branch of BDNF signaling. Indeed, both PKC and RKIP were significantly down‐regulated. Conclusions: Chronic ethanol exposure impaired neuronal differentiation of neuroblastoma cells and BDNF signaling, particularly the PKC‐dependent branch. RKIP, acting as a signaling switch at the merge of the PKC cascade and the Raf/MEK/ERK cascade, was associated with neuronal differentiation and significantly reduced in ethanol treatment. Moreover, PKC expression itself was even more strongly reduced. In contrast, members of the Raf‐1/MEK/ERK cascade were less affected and the observed changes were not associated with impaired differentiation. Thus, reduced RKIP and PKC levels and subsequently reduced positive feedback on ERK activation provide an explanation for the striking effects of long‐term ethanol exposure on BDNF signal transduction and neuronal differentiation, respectively.