HUMAN MONOCYTES MAINTAINED IN CULTURE ACQUIRE FUNCTIONAL RESPONSIVENESS TO PLATELET-ACTIVATING FACTOR THAT IS INDEPENDENT OF INCREASES IN PROTEIN TYROSINE PHOSPHORYLATION

1. Acute (day 0) stimulation with platelet-activating factor (PAF) did not elicit superoxide anion (02^-) generation from adherent monocytes. However, by day 2 of culture, PAF induced an increase in O2^- generation that was inhibited by pretreat-ment with the PAF receptor antagonist WEB 2086. 2. The lack of effect of PAF on O2^- generation was not due to the absence of receptors, as PAF stimulated an increase in tyrosine phosphorylation and intracellular calcium ([Ca²⁺]_i) on both days 0 and 2 of culture. 3. Pretreatment with the protein tyrosine kinase inhibitor methyl 2 ,5-dihydroxycinnamate inhibited PAF-induced tyrosine phosphorylation; however, this inhibitor failed to inhibit PAF-induced O₂^- generation. In contrast, pretreatment with the protein kinase C inhibitor staurosporine had no effect on PAF-induced tyrosine phosphorylation, but did inhibit PAF-induced O₂^- generation. 4. These results indicate that monocytes maintained in culture acquire a functional response to PAF through a mechanism that appears to be independent of PAF receptor expression, coupling to increases in [Ca²⁺]_i or tyrosine phosphorylation.     

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.     

p38丝裂原活化蛋白激酶信号级联在炎症反应中的作用

在急、慢性疾病中，细胞释放的炎症介质可以活化多种信号转导级联反应，丝裂原活化蛋白激酶(MAPK)信号转导通道在招募白细胞于炎症部位聚集起着重要的作用。同时，p38MAPK异构体的活化可以激活致炎细胞因子，而后刺激白细胞活化。然而，p38MAPK引起的白细胞招募这一系列的功能过程包括：粘附、游走和效应器的功能如氧化爆发以及p38MAPK介导的复杂细胞因子网络在炎症中的作用仍有待研究。针对减少炎症介质产生和以p38MAPK为治疗靶点的研究正在进行中，不远的将来可能会成为治疗炎症疾病的新策略。     

血管通透性的调节和游离微血管技术在其研究中的应用

Vascular hyperpermeability is a cardinal feature of inflammation or bum in which an array of inflammatory mediators can cause such changes in the microvessels. The fimctional measures of microvascular exchange that represent the properties of microvascular wails are the permeability coefficients which have been reported from measurements on intact whole organisms (including human subjects}, on perfused tissues and organs, on single perfused microvessels, and on monolayers of cultured microvascular endothelial cells. In this review, we summarize some experiments of vascular permeability in individually isolated perfused microvessels.     

Raf-1 kinase,epidermal growth factor receptors,and mutant ras proteins in colonic carcinomas

Epidermal growth factor receptors (EGFR) andras mutations are known to play a significant role in controlling cell growth and tumor promotion. Both of them transmit mitogenic signals to the nucleus by activation of Raf-1 kinase. In this study, the expression of EGFR and mutant Ras proteins, and, for the first time, the expression, phosphorylation and kinase activity of Raf-1 kinase have been determined in paired samples of colorectal cancer and mucosa. The tumor and mucosa samples did not differ significantly with regard to Raf-1 kinase content and activity. A major difference between tumors and mucosa was found, however, in the phosphorylation of Raf-1. Most of the mucosa samples (13/20), but only 1/20 of the cancer samples, contained hyperphosphorylated Raf-1. EGFR were significantly (p=0.0025) decreased in the tumors. The decreased phosphorylation of Raf-1 in colonic carcinomas could be the result of activation of Raf-1 phosphatases or inactivation of kinases phosphorylating Raf-1. New forms of treatment based on EGFR overexpression do not seem to be suitable for the majority of colonic cancers.This work was supported by the state of Baden-Württemberg (Verbundforschungsprojekt: Aufklärung von Mechanismen der Tumorentstehung und Tumorabwehr).     

外源性三磷酸腺苷对肾小管上皮细胞增殖的影响

观察外源性三磷酸腺苷（ＡＴＰ）对肾小管上皮细胞株ＬＬＣＰＫ１增殖的影响。方法通过测定３Ｈ－胸腺嘧啶掺入、细胞计数以及细胞内丝裂素活化蛋白激酶活性，并与表皮生长因子（ＥＧＦ）的作用比较。结果发现ＡＴＰ呈浓度依赖性促进细胞的ＤＮＡ合成，并可使细胞计数增加，同时激活细胞内的丝裂素活化蛋白激酶，其作用与ＥＧＦ相似。腺苷与ＡＴＰ有类似作用，但较弱。核苷酸转运蛋白抑制剂对４－硝基苯６－硫基甙并不能抑制ＡＴＰ及腺苷的作用。结论细胞外ＡＴＰ可促进肾小管上皮细胞增殖，并可增强ＥＧＦ的促增殖作用，这一作用可能是通过膜受体介导的细胞内丝裂素活化蛋白激酶活化而实现的     

磷脂酶C与生殖

磷脂酶C(PLC)是磷脂酰肌醇信号转导途径中一个关键酶。目前确认的哺乳类PLC共有PLC β、PLC γ、PLC δ、PLC ε和最近新发现的PLC ζ 5种亚型 ,12种同工酶。不同亚型的结构、调控和组织分布各有差异。PLC在调控信号转导通路中的特性使其在顶体反应、卵子激活中发挥了巨大的作用。本文综述了PLC家族 5种亚型的结构、调控机制及PLC在男性生殖领域的相关内容 ,包括PLC引起卵子发生Ca2 + 振荡、激活卵子、促进胚胎发育等 ,并进一步探讨了PLC在临床上可能的应用前景。     

肿瘤多药耐药与细胞信号转导的研究进展

肿瘤多药耐药是肿瘤治疗失败的重要原因,最近研究发现细胞信号转导通路在肿瘤细胞耐药形成的过程中具有重要作用,主要包括凋亡、NF-κB、MAPK、PI3K/Akt通路及肿瘤干细胞等方面,而应用相应的通路阻断剂逆转耐药将成为提高肿瘤治疗效果的亮点。本文主要对以上与肿瘤多药耐药相关的细胞信号转导通路作一综述。