The G Protein-Coupled Serotonin 1A Receptor Augments Protein Kinase Cε-Mediated Neurogenesis in Neonatal Mouse Hippocampus—PKCε-Mediated Signaling in the Early Hippocampus

The neurotransmitter serotonin (5-HT) plays an important role in mood disorders. It has been demonstrated that 5-HT signaling through 5-HT_1A receptors (5-HT_1A-R) is crucial for early postnatal hippocampal development and later-life behavior. Although this suggests that 5-HT_1A-R signaling regulates early brain development, the mechanistic underpinnings of this process have remained unclear. Here we show that stimulation of the 5-HT_1A-R at postnatal day 6 (P6) by intrahippocampal infusion of the agonist 8-OH-DPAT (D) causes signaling through protein kinase Cε (PKCε) and extracellular receptor activated kinase ½ (ERK1/2) to boost neuroblast proliferation in the dentate gyrus (DG), as displayed by an increase in bromodeoxy-uridine (BrdU), doublecortin (DCX) double-positive cells. This boost in neuroproliferation was eliminated in mice treated with D in the presence of a 5-HT_1A-R antagonist (WAY100635), a selective PKCε inhibitor, or an ERK1/2-kinase (MEK) inhibitor (U0126). It is believed that hippocampal neuro-progenitors undergoing neonatal proliferation subsequently become postmitotic and enter the synaptogenesis phase. Double-staining with antibodies against bromodeoxyuridine (BrdU) and neuronal nuclear protein (NeuN) confirmed that 5-HT_1A-R → PKCε → ERK1/2-mediated boosted neuroproliferation at P6 also leads to an increase in BrdU-labeled granular neurons at P36. This 5-HT_1A-R-mediated increase in mature neurons was unlikely due to suppressed apoptosis, because terminal deoxynucleotidyl transferase dUTP nick-end labeling analysis showed no difference in DNA terminal labeling between vehicle and 8-OH-DPAT-infused mice. Therefore, 5-HT_1A-R signaling through PKCε may play an important role in micro-neurogenesis in the DG at P6, following which many of these new-born neuroprogenitors develop into mature neurons.     

Characterization of the Transient Deficiency of PKC Isozyme Levels in Immature Cord Blood T Cells and Its Connection to Anti-Allergic Cytokine Profiles of the Matured Cells

Cord blood T cells (CBTC) from a proportion of newborns express low/deficient levels of some protein kinase C (PKC) isozymes, with low levels of PKCζ correlating with increased risk of developing allergy and associated decrease in interferon-gamma (IFN-γ) producing T cells. Interestingly, these lower levels of PKCζ were increased/normalized by supplementing women during pregnancy with n-3 polyunsaturated fatty acids. However, at present, we have little understanding of the transient nature of the deficiency in the neonate and how PKCζ relates to other PKC isozymes and whether their levels influence maturation into IFN-γ producing T cells. There is also no information on PKCζ isozyme levels in the T cell subpopulations, CD4⁺ and CD8⁺ cells. These issues were addressed in the present study using a classical culture model of neonatal T cell maturation, initiated with phytohaemagglutinin (PHA) and recombinant human interleukin-2 (rhIL-2). Of the isozymes evaluated, PKCζ, β2, δ, μ, ε, θ and λ/ι were low in CBTCs. The PKC isozyme deficiencies were also found in the CD4⁺ and CD8⁺ T cell subset levels of the PKC isozymes correlated between the two subpopulations. Examination of changes in the PKC isozymes in these deficient cells following addition of maturation signals showed a significant increase in expression within the first few hours for PKCζ, β2 and μ, and 1–2 days for PKCδ, ε, θ and λ/ι. Only CBTC PKCζ isozyme levels correlated with cytokine production, with a positive correlation with IFN-γ, interleukin (IL)-2 and tumour necrosis factor-alpha (TNF), and a negative association with IL-9 and IL-10. The findings reinforce the specificity in using CBTC PKCζ levels as a biomarker for risk of allergy development and identify a period in which this can be potentially ‘corrected’ after birth.     

The Cross Talk between cGMP Signal Pathway and PKC in Pulmonary Endothelial Cell Angiogenesis

Angiogenic proliferation of vascular endothelial cells is believed to play an important role in pulmonary vascular remodeling in pulmonary arterial hypertension. In the present study, we found that c-GMP (cyclic guanosine monophosphate) inhibited the proliferation and tube formation of pulmonary vascular endothelial cells induced by TGF-β1, and that this process was reversed by PKG (protein kinase G) inhibitor and PKC (protein kinase C) inhibitor. In addition, small interfering RNA (siRNA) targeting ERK also reduced cellular proliferation. Furthermore, western blotting showed that cGMP down-regulated the phosphorylation level of ERK1/2, which was reversed not only by PKG inhibitor but also by PKC inhibitor. Silencing different PKC isoforms showed that PKCΔ, PKCγ and PKCα were involved in ERK phosphorylation, suggesting that PKC kinases have a permissive action. Three subtypes, PKCΔ, PKCγ and PKCα are likely to be involved the phosphorylation suppression of ERK included cGMP. Taken together, these data suggest that ERK phosphorylation mediates the proliferation of pulmonary vascular endothelial cells, and PKC kinases have a permissive action in this process.     

Cell‐to‐Cell Communication of Neurons Is Impaired by Metals

Several metals are known to block voltage‐activated calcium channels at relatively high concentrations, and some also block agonist‐activated channels. However some of the actions of metals which occur at the lowest concentrations are on plastic responses of neurons, that is, responses which show prolonged changes after specific kinds of manipulation. We have investigated the effects of lead on the process of long‐term potentiation (LTP), an electrical response which is believed to be a component of learning and memory. LTP is an increased response to a stimulus after a patterned input, and LTP is reduced in aged animals and in animals with genetic backgrounds that result in a poor ability to learn. In humans there is strong evidence that children exposed to lead early in life have a reduced IQ. Therefore our hypothesis was that lead might be acting on LTP, and that this could be the basis of the IQ decrement seen in exposed children. We exposed rats to lead using two different protocols: chronic in vivo exposure and perfusion of lead‐containing solutions over brain slices of control rats. We find similar effects in both studies. We recorded LTP in two different regions of hippocampus, in CA1 where LTP is dependent upon activation of N‐methyl‐D‐aspartate (NMDA) receptors, and in CA3 where LTP is primarily presynaptic in origin and independent of NMDA receptors. We recorded from isolated and perfused brain slices of either control or exposed animals at two ages, 30 and 60 days. In CA1 lead did not significantly alter the synaptic responses recorded at about 30% of maximal amplitude, but reduced LTP at either age. In contrast, in CA3 lead reduced LTP in slices from 30‐day old animals after exposure to lead either with chronic in vivo exposure or with acute in vitro exposure, but increased the response in CA3 in 60‐day old animals exposed by either route. We have evidence that this action is mediated neither by blockade of voltage‐activated calcium nor NMDA channels, but is likely an action of protein kinase C, an enzyme necessary for induction of LTP at both sites.     

WSN中基于身份的高效多播认证协议

分析了无线传感器网络中已有多播认证协议的不足,给出了基于PKC的WSN安全协议研究进展,并提出一种基于身份的高效多播认证协议.该协议具有消息恢复功能,可有效缩短签名长度,减少协议的通信和计算开销,克服公钥密码体制开销大的缺点.在随机预言模型下证明了协议在适应性选择消息攻击和身份攻击下是存在性不可伪造的.最后,基于MICA2DOT无线传感器网络节点对协议的能量消耗进行了定量分析,结果表明,本协议的性能优于HESS、Zhang和BLS等协议,能更好地适用于资源受限的WSN环境.     

分布式环境下的访问控制*

介绍了授权管理系统PMI,它可以有效地解决在分布式环境下的授权和访问控制问题。讨论了有关PMI的一些关键性的技术,属性证书与公钥证书之间的关系以及PMI的实现方式,并提出将要进行的研究工作。     

烟碱对大鼠脑内蛋白激酶A 和C活性的影响

目的: 观察烟碱对脑内蛋白激酶A 和C 活性的影响。方法: 在烟碱诱导N 受体处于激动态、亚急性失敏、急性失敏和慢性失敏态时, 处死大鼠取全脑匀浆。分别加入PKA 特异性生物素化底物Kemptide和PKC 特异性底物生物素化Neurogranine, 用³²P掺入底物法测定大鼠全脑中蛋白激酶A 和C 的活性。利用基因芯片技术检测慢性失敏时PKA 和PKC 相关基因表达的变化。结果: N 受体激动状态下对PKA 和PKC 的活性没有影响;N 受体亚急性、急性和慢性失敏时使PKA 和PKC 的活性降低。慢性失敏时,PKC Ⅲ基因表达增加, 而PKC 中α、γ、ζ等基因表达没有变化;cAMP 反应元素结合蛋白、cAMP反应元素调节因子、cAMP 磷脂酶、cAMP 依赖性蛋白激酶Ⅱ等6 种基因表达无明显改变。结论: 烟碱作用使N 受体失敏耐受时, 可降低脑内PKA 和PKC的活性, 使脑内信号转导通路发生适应性改变, 这些变化可能是烟碱耐受的重要生化基础。     

传感器节点相互协作的广播认证

针对无线传感器网络（WSN）中基于数字签名的公钥加密体制的广播认证需要耗费大量的能量,以及传感器节点资源有限的问题,为了减少传感器节点的能量耗费和加快传感器节点的认证,提出一种传感器节点相互协作的广播认证方案。首先,用户向无线传感器网络的组网络广播其签名信息,但不广播签名信息中点的纵坐标;然后,组网络中的高能量节点依据点的横坐标和椭圆曲线方程计算得出纵坐标,并将其广播给组内的一般节点,同时利用vBNN-IBS数字签名对用户广播的签名信息进行认证,并转播有效的签名信息;最后,组网络内的一般节点收到纵坐标后,利用椭圆曲线方程验证其有效性和正确性,同时执行和高能节点相同的签名认证过程,并转播有效的签名信息。此外,该方案通过整合立即撤销和自动撤销以最大限度地减小授权撤销列表（ARL）的长度。仿真实验表明,当认证节点收到来自邻居节点的数据包达到一定数目时,该方案的能量耗费和认证总时间比利用WSN中传感器节点间的相互协作来加速vBNN-IBS的签名方案分别减少了41%和66%。