The aging brain, a key target for the future: The protein kinase C involvement

The brain represents the primary centre for the regulation and control of all our body activities, receiving and interpreting sensory impulses and transmitting information to the periphery. Most importantly, it is also the seat of consciousness, thought, emotion and especially memory, being in fact able to encode, store and recall any information. Memory is really what makes possible so many of our complex cognitive functions, including communication and learning, and surely without memory, life would lose all of its glamour and purpose. Age-associated mental impairment can range in severity from forgetfulness at the border with pathology to dementia, such as in Alzheimer's disease. In recent years, one of the most relevant observations of research on brain aging relates to data indicating that age-related cognitive decline is not only due to neuronal loss, as previously thought; instead, scientists now believe that age-associated functional changes have more to do with the dysfunctions occurring over time. Within this context a prominent role is certainly played by signal transduction cascades which guarantee neuronal cell to elaborate coordinated responses to the multiple signals coming from the outside and to adapt itself to the environmental changes and requests. This review will focus the attention on protein kinase C pathway, with a particular interest on its activation process, and on the role of protein-lipid and protein-protein interactions to selectively localize the cellular responses. Furthermore, information is emerging and will be discussed on the possibility of mRNA stabilization through PKC activation. This review will also approach the issue on how alterations of these molecular cascades may have implications in physiological and pathological brain aging, such as Alzheimer's disease.     

柴胡疏肝散、四君子汤对肝郁、脾虚大鼠Th细胞蛋白激酶C表达的影响

目的研究柴胡疏肝散、四君子汤对肝郁、脾虚大鼠Th细胞蛋白激酶C(PKC)表达的影响及其意义。方法应用RT—PCR法研究柴胡疏肝散、四君子汤对Th细胞PKCmRNA表达的影响。结果脾虚时PKCmRNA表达水平明显低于正常对照组 (P <0 .0 5 ) ,四君子汤治疗后恢复正常 (P <0 .0 5 ) ,柴胡疏肝散治疗后仍明显低于正常对照组 ;肝郁时PKCmRNA表达水平明显高于正常对照组 (P <0 .0 5 ) ,柴胡疏肝散治疗后恢复正常 (P <0 .0 5 ) ,但四君子汤治疗效应不明显。结论肝脾两脏在T细胞尤其是Th0的活化中具有相关性 ;PKC参与了肝脾这种相关的发生。     

卵巢癌中蛋白激酶C的表达及其临床意义

目的　探讨上皮性卵巢癌组织蛋白激酶C (proteinkinaseC ,PKC)的表达和化疗耐药的关系 ,以及与P -糖蛋白 (P -gp)的相关性。方法　用免疫组化S -P法检测 35例卵巢上皮性肿瘤组织、 2 0例卵巢良性肿瘤组织和 2 0例正常卵巢组织中PKC和P -gp的表达 ,并进行相关临床因素分析。结果　①PKC、P -gp在卵巢恶性肿瘤中的表达明显高于在良性及正常组织中的表达 ;并且PKC和P -gp的表达有相关性 (P <0 0 5 ) ;②卵巢癌PKC的表达与临床病理因素无直接关系 ;③恶性肿瘤中 ,初治和复发的PKC表达阳性率分别为 34 8%和 75 % ;④化疗对PKC表达阳性和阴性卵巢癌患者的有效率分别为 2 3 5 %、 6 6 7% (P <0 0 5 ) ;⑤PKC表达阴性患者的预后优于阳性者 (P =0 0 39)。结论　PKC表达与卵巢癌组织化疗耐药明显相关 ,可能在P -gp介导的卵巢癌多药耐药中起重要作用。     

雌激素替代治疗大鼠海马结构PKC阳性细胞的变化

目的 :观察雌性大鼠行去势后以及雌激素替代治疗海马结构蛋白激酶C ( proteinkinaseC ,PKC)阳性细胞的变化 ,通过该模型研究绝经期后女性情绪烦躁、记忆下降等神经精神症状的分子机制。方法 :将大鼠分为对照组、去势 3个月组和去势后雌激素替代治疗 3个月组 ,用免疫组织化学方法检测海马结构PKC阳性细胞的变化。结果 :PKC阳性细胞主要分布于下托和齿状回的颗粒层 ,其中齿状回内的阳性细胞较下托的多。去势 3个月组与对照组相比 ,齿状回内的PKC阳性细胞没有显著性减少 (P >0 .0 5 ) ,下托PKC阳性细胞显著减少 (P <0 .0 5 ) ;雌激素治疗组与对照组相比 ,下托细胞数量有所减少 ,但无显著性差异 (P >0 .0 5 )。结论 :海马结构下托PKC阳性细胞的减少可能在绝经后女性情绪烦躁、记忆下降等症状中起重要的作用。     

Immunochemical characterization of mouse brain-associated theta (Thy-1) antigen.

The Thy-1 antigens or rat brain and thymus have been isolated and chemically characterized, but those of mice have not been identified. Moreover, it is uncertain whether the antigens are glycolipids or glycoproteins. This study with highly purified preparations of gangliosides GM₁, ¹GD_1a, GD_1b and GT_1b from bovine brain and several ganglioside fractions from mouse brain showed that Thy-1 activity does not reside in gangliosides, but rather in the chloroform-methanol-insoluble residue of brain remaining after extraction of gangliosides. The antigen could be solubilized from this residue with a non-ionic detergent. The antigenic activity of the solubilized preparation was heat-labile but resistant to periodate. The chemical properties of the Thy-1 antigen of mouse brain are discussed.     

Insulin inhibits phagocytosis in normal human neutrophils via PKCα/β-dependent priming of F-actin assembly

Objective: This study investigated the effects of insulin on the phagocytosis of C3bi – and IgG-opsonized yeast particles in normal human neutrophils. Methods: Neutrophils were incubated in different insulin concentrations for 30 minutes and stimulated by C3bi – or IgG-opsonized yeast particles. Phagocytosis was quantified by both light microscopy and FACscan flow cytometry. Laser confocal microscopy was used for quantification of F-actin levels. Results: Elevated insulin concentrations decreased neutrophil phagocytosis of both types of targets. This defect was shown to be in part due to a delayed phagocytosis in the presence of insulin. Following a 30 minute incubation, insulin was found to increase the accumulation of cortical F-actin, without affecting the total cellular F-actin content. The specific PKCα/β inhibitor, Go6976, abolished the insulin-mediated increase in cortical F-actin content and both Go6976 and the PKCα/β/δ/ε-specific inhibitor GF109203X reversed the inhibitory effects of insulin on phagocytosis. Conclusion: Hyperinsulinemia in vitro can inhibit phagocytosis of opsonized targets in normal human neutrophils. This effect of insulin is dependent on activation of PKCα and/or PKCβ, and these insulin signals may interfere with the dynamic assembly/disassembly and/or distribution of F-actin, which is required for the phagocytosis process. Received 8 July 2005; accepted 13 October 2005 without revision I. Ahnfelt-R?nne     

Autocrine motility factor (neuroleukin, phosphohexose isomerase) induces cell movement through 12-lipoxygenase-dependent tyrosine phosphorylation and serine dephosphorylation events

Autocrine motility factor (AMF) is one of the motility cytokines regulating tumor cell migration, therefore identification of the signaling pathway coupled with it has critical importance. Previous studies revealed several elements of this pathway predominated by lipoxygenase-PKC activations but the role for tyrosine kinases remained questionable. Motility cytokines frequently have mitogenic effect as well, producing activation of overlapping signaling pathways therefore we have used B16a melanoma cells as models where AMF has exclusive motility effect. Our studies revealed that in B16a cells AMF initiated rapid (1–5 min) activation of the protein tyrosine kinase (PTK) cascade inducing phosphorylation of 179, 125, 95 and 40/37 kD proteins which was mediated by upstream cyclo- and lipoxygenases. The phosphorylated proteins were localized to the cortical actin-stress fiber attachment zones in situ by confocal microscopy. On the other hand, AMF receptor activation induced significant decrease in overall serine-phosphorylation level of cellular proteins accompanied by serine phosphorylation of 200, 90, 78 and 65 kd proteins. The decrease in serine phosphorylation was independent of PTKs, PKC as well as cyclo- and lipoxygenases. However, AMF induced robust translocation of PKCα to the stress fibers and cortical actin suggesting a critical role for this kinase in the generation of the motility signal. Based on the significant decrease in serine phosphorylation after AMF stimulus in B16a cells we postulated the involvement of putative serine/threonine phosphatase(s) upstream lipoxygenase and activation of the protein tyrosine kinase cascade downstream cyclo- and lipoxygenase(s) in the previously identified autocrine motility signal. This revised version was published online in July 2006 with corrections to the Cover Date.     

蛋白激酶Cθ信号途径在结核分枝杆菌抗原激活人γδT细胞增殖和分化中的作用

目的 研究蛋白激酶Cθ(protein kinase Cθ,PKCθ)信号途径在结核分枝杆菌抗原(Mycobacterium tuberculosis antigen,Mtb-Ag)激活人γδT细胞增殖和分化中的作用.方法 健康人外周血单个核细胞(PBMC)用Mtb-Ag和IL-2优势刺激和扩增γδT细胞,或预先用5.0μmol/L Rottlerin(楸毒素)预处理,培养不同时间后,用流式细胞术(FCM)检测γδT细胞表面活化分子和细胞因子表达;同时采用活体染料羧基荧光素乙酰乙酸(CFSE)标记细胞,流式细胞术分析Mtb-Ag刺激γδT细胞后的增殖和各子代细胞百分率.结果 PBMC经Mtb-Ag刺激后3d,γδT细胞CD69和CD25表达分别为46.2%和45.6%,而Rotderin预处理显著地抑制了CD69和CD25表达(P＜0.01);PBMC经Mtb-Ag激活培养5、10和15d,培养扩增细胞中的γδT细胞比例分别为9.6%、54.6%和82.4%,其中第5天已有少部分γδT细胞发生增殖,第10天和第15天时几乎全部γδT细胞分裂都在6代以上,用Rottlerin预处理,显著抑制了γδT细胞增殖反应,但在培养第10天后仍有少部分γδT细胞发生增殖反应;同时在培养第7天、14天和21天,用PMA(佛波酯)+Ionomycin(离子霉素)再刺激后,产生IFN-γ的γδT细胞均在80%左右;培养21d时,有2.6%的γδT细胞表达IL-4.在Rottlerin预处理组产生TH1型细胞因子IFN-γ的γδT细胞均显著减少(P＜0.05),而γδT细胞表达TH2型细胞因子IL-4则几乎完全抑制(P＜0.01).结论 PKCθ信号途径在Mtb-Ag刺激γδT细胞的增殖和分化中均起重要作用.