Glutamate receptor-mediated regulation of c-fos expression in cultured microglia

It has been recently shown that the expression of various types of neurotransmitter receptors is not restricted to neurons but also observed in a majority of glial cells. However, their function in glial cells is not known well in both physiological and pathological conditions. Here, we investigated the role of glutamate receptor on c-fos gene expression in primary cultured and BV-2 microglia. Our results demonstrated that both c-fos mRNA and protein were dramatically induced following treatment with various glutamate receptor agonists (500muM); N-methyl-d-aspartic acid, kainic acid, (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and (RS)-3,5-dihydroxyphenylglycine. The responses were significantly suppressed by specific antagonists and also by calcium chelating agents EGTA and BAPTA-AM. Our results suggest that glutamate receptor activation regulates c-fos gene expression by modifying intracellular calcium levels in microglia. These findings might provide an insight in to understanding the function of microglial glutamate receptors in neuron-to-glial interaction under the excitotoxic conditions.     

Regulation of the dual specificity protein phosphatase, DsPTP1, through interactions with calmodulin

Reversible phosphorylation is a key mechanism for the control of intercellular events in eukaryotic cells. In animal cells, Ca2+/CaM-dependent protein phosphorylation and dephosphorylation are implicated in the regulation of a number of cellular processes. However, little is known on the functions of Ca2+/CaM-dependent protein kinases and phosphatases in Ca2+ signaling in plants. From an Arabidopsis expression library, we isolated cDNA encoding a dual specificity protein phosphatase 1, which is capable of hydrolyzing both phosphoserine/threonine and phosphotyrosine residues of the substrates. Using a gel overlay assay, we identified two Ca2+-dependent CaM binding domains (CaMBDI in the N terminus and CaMBDII in the C terminus). Specific binding of CaM to two CaMBD was confirmed by site-directed mutagenesis, a gel mobility shift assay, and a competition assay using a Ca2+/CaM-dependent enzyme. At increasing concentrations of CaM, the biochemical activity of dual specificity protein phosphatase 1 on the p-nitrophenyl phosphate (pNPP) substrate was increased, whereas activity on the phosphotyrosine of myelin basic protein (MBP) was inhibited. Our results collectively indicate that calmodulin differentially regulates the activity of protein phosphatase, dependent on the substrate. Based on these findings, we propose that the Ca2+ signaling pathway is mediated by CaM cross-talks with a protein phosphorylation signal pathway in plants via protein dephosphorylation.     

Interaction between glucose-regulated destruction domain of DNA topoisomerase IIalpha and MPN domain of Jab1/CSN5

DNA topoisomerase (topo) IIalpha, an essential enzyme for cell proliferation, is targeted to a proteasome-dependent degradation pathway when human tumor cells are glucose-starved. Here we show that the topo IIalpha destabilization depends on the newly identified domain, GRDD (glucose-regulated destruction domain), which was mapped to the N-terminal 70-170 amino acid sequence. Indeed, the deletion of GRDD conferred a stable feature on topo IIalpha, whereas the fusion of GRDD rendered green fluorescent protein unstable under glucose starvation conditions. Nuclear localization was a prerequisite for GRDD function, because the inhibition of nuclear translocation resulted in the suppression of GRDD-mediated topo IIalpha degradation. Further, GRDD was identified as an interactive domain for Jab1/CSN5, which promoted the degradation of topo IIalpha in a manner dependent on the MPN (Mpr1p/Prd1p N terminus) domain. Depleting Jab1/CSN5 by antisense oligonucleotide and treating cells with the CSN-associated kinase inhibitor, curcumin, inhibited topo IIalpha degradation induced by glucose starvation. These findings demonstrate that GRDD can act as a stress-activated degron for regulating topo IIalpha stability, possibly through interaction with the MPN domain of Jab1/CSN5.     

Proteome analysis by bio-active ceramic water in rat liver: contribution to antioxidant enzyme expression, SOD I

The purpose of this study was to investigate the protective effect of bio-active ceramic water on rat liver. Male Wistar rats were divided into 4 groups of 15 animals each. Groups 1 and 2 were fed bio-active ceramic water and tap water for 4 months, respectively. Groups 3 and 4 were treated with the same condition for 12 months. The changes of protein expression of these four groups were investigated using two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Eleven proteins were significantly up-regulated in bio-active ceramic water treated rat liver including aldehyde dehydrogenase I and II, albumin, fructose-1,6-bisphosphatase, and superoxide dismutase I (SOD I). The most highly expressed protein, SOD I with up-regulated enzyme activity, was confirmed by immunoblots as a major antioxidant capable of detoxifying normally generated reactive oxygen species. These data suggest that modified protein expression of the liver contributes to enhance liver function.     

Quantitative kinetic analysis of nucleolar breakdown and reassembly during mitosis in live human cells

One of the great mysteries of the nucleolus surrounds its disappearance during mitosis and subsequent reassembly at late mitosis. Here, the relative dynamics of nucleolar disassembly and reformation were dissected using quantitative 4D microscopy with fluorescent protein-tagged proteins in human stable cell lines. The data provide a novel insight into the fates of the three distinct nucleolar subcompartments and their associated protein machineries in a single dividing cell. Before the onset of nuclear envelope (NE) breakdown, nucleolar disassembly started with the loss of RNA polymerase I subunits from the fibrillar centers. Dissociation of proteins from the other subcompartments occurred with faster kinetics but commenced later, coincident with the process of NE breakdown. The reformation pathway also follows a reproducible and defined temporal sequence but the order of reassembly is shown not to be dictated by the order in which individual nucleolar components reaccumulate within the nucleus after mitosis.     

Targeted deletion of protein kinase C lambda reveals a distribution of functions between the two atypical protein kinase C isoforms

Protein kinase C lambda (PKClambda) is an atypical member of the PKC family of serine/threonine kinases with high similarity to the other atypical family member, PKCzeta. This similarity has made it difficult to determine specific roles for the individual atypical isoforms. Both PKClambda and PKCzeta have been implicated in the signal transduction, initiated by mediators of innate immunity, that culminates in the activation of MAPKs and NF-kappaB. In addition, work from invertebrates shows that atypical PKC molecules play a role in embryo development and cell polarity. To determine the unique functions of PKClambda, mice deficient for PKClambda were generated by gene targeting. The ablation of PKClambda results in abnormalities early in gestation with lethality occurring by embryonic day 9. The role of PKClambda in cytokine-mediated cellular activation was studied by making mouse chimeras from PKClambda-deficient embryonic stem cells and C57BL/6 or Rag2-deficient blastocysts. Cell lines derived from these chimeric animals were then used to dissect the role of PKClambda in cytokine responses. Although the mutant cells exhibited alterations in actin stress fibers and focal adhesions, no other phenotypic differences were noted. Contrary to experiments using dominant interfering forms of PKClambda, mutant cells responded normally to TNF, serum, epidermal growth factor, IL-1, and LPS. In addition, no abnormalities were found in T cell development or T cell activation. These data establish that, in vertebrates, the two disparate functions of atypical PKC molecules have been segregated such that PKCzeta mediates signal transduction of the innate immune system and PKClambda is essential for early embryogenesis.     

The role of the p38 mitogen-activated protein kinase, extracellular signal-regulated kinase, and phosphoinositide-3-OH kinase signal transduction pathways in CD40 ligand-induced dendritic cell activation and expansion of virus-specific CD8+ T cell memory responses

Mature dendritic cells (DCs) are central to the development of optimal T cell immune responses. CD40 ligand (CD40L, CD154) is one of the most potent maturation stimuli for immature DCs. We studied the role of three signaling pathways, p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), and phosphoinositide-3-OH kinase (PI3K), in CD40L-induced monocyte-derived DC activation, survival, and expansion of virus-specific CD8(+) T cell responses. p38 MAPK pathway was critical for CD40L-mediated up-regulation of CD83, a marker of DC maturation. CD40L-induced monocyte-derived DC IL-12 production was mediated by both the p38 MAPK and PI3K pathways. CD40L-mediated DC survival was mostly mediated by the PI3K pathway, with smaller contributions by p38 MAPK and ERK pathways. Finally, the p38 MAPK pathway was most important in mediating CD40L-stimulated DCs to induce strong allogeneic responses as well as expanding virus-specific memory CD8(+) T cell responses. Thus, although the p38 MAPK, PI3K, and ERK pathways independently affect various parameters of DC maturation induced by CD40L, the p38 MAPK pathway within CD40L-conditioned DCs is the most important pathway to maximally elicit T cell immune responses. This pathway should be exploited in vivo to either completely suppress or enhance CD8(+) T cell immune responses.     

The asymptotic behavior of a chemostat model with the Beddington-DeAngelis functional response

In this paper, the global asymptotic behavior of a chemostat model with Beddington-DeAngelis functional response is studied. The conditions for the global asymptotical stability of the model with time delays are obtained via monotone dynamical systems. Our results demonstrate that those time delays affect the competitive outcome of the organisms.     

嗜盐菌素HalC8基因簇克隆与分析

采用基因组部分文库及锚定PCR技术,克隆了嗜盐菌素HalC8编码基因及其上下游可能的相关基因共约9.3kb的DNA序列。序列分析表明已知序列至少含有6个ORF,包括上游编码跨膜蛋白的halU基因、编码可能的调节蛋白的halR基因,编码嗜盐菌素HalC8及其免疫蛋白HalⅠ的proC8基因、以及位于proC8基因下游的编码可能的转运蛋白的halT1,halT2和halT3基因。这是国际上首次对嗜盐菌素基因簇可能的相关基因的克隆。     

芹菜化学成分及药理活性研究进展

介绍了芹菜的化学成分及药理活性研究概况。芹菜主要含有挥发油、脂肪酸和黄酮类等化学成分,具有抗菌杀虫、抗氧化、抗肿瘤及抗心血管疾病等药理活性。作为药食两用且广泛种植的植物,对其进行进一步的研究和开发具有重要的意义。