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71.
PP2A activates brassinosteroid-responsive gene expression and plant growth by dephosphorylating BZR1 总被引:4,自引:0,他引:4
72.
Identification of NaCl stress-responsive apoplastic proteins in rice shoot stems by 2D-DIGE 总被引:1,自引:0,他引:1
Plants have evolved sophisticated systems to cope with adverse environmental conditions such as cold, drought, and salinity. Although a number of stress response networks have been proposed, the role of plant apoplast in plant stress response has been ignored. To investigate the role of apoplastic proteins in the salt stress response, 10-day old rice plants were treated with 200mM NaCl for 1, 6 or 12h, and the soluble apoplast proteins of rice shoot stems were extracted for differential analysis, compared with untreated controls, by 2-D DIGE saturation labeling techniques. One hundred twenty-two significantly changed spots were identified by LC-MS/MS, and 117 spots representing 69 proteins have been identified. Of these proteins, 37 are apoplastic proteins according to the bioinformatic analysis. These proteins are mainly involved in the processes of carbohydrate metabolism, oxido-reduction, and protein processing and degradation. According to their functional categories and cluster analysis, a stress response model of apoplastic proteins has been proposed. These data indicate that the apoplast is important in plant stress signal reception and response. 相似文献
73.
74.
Neurotransmitter release regulated by a MALS-liprin-alpha presynaptic complex 总被引:2,自引:0,他引:2 下载免费PDF全文
Olsen O Moore KA Fukata M Kazuta T Trinidad JC Kauer FW Streuli M Misawa H Burlingame AL Nicoll RA Bredt DS 《The Journal of cell biology》2005,170(7):1127-1134
Synapses are highly specialized intercellular junctions organized by adhesive and scaffolding molecules that align presynaptic vesicular release with postsynaptic neurotransmitter receptors. The MALS/Veli-CASK-Mint-1 complex of PDZ proteins occurs on both sides of the synapse and has the potential to link transsynaptic adhesion molecules to the cytoskeleton. In this study, we purified the MALS protein complex from brain and found liprin-alpha as a major component. Liprin proteins organize the presynaptic active zone and regulate neurotransmitter release. Fittingly, mutant mice lacking all three MALS isoforms died perinatally with difficulty breathing and impaired excitatory synaptic transmission. Excitatory postsynaptic currents were dramatically reduced in autaptic cultures from MALS triple knockout mice due to a presynaptic deficit in vesicle cycling. These findings are consistent with a model whereby the MALS-CASK-liprin-alpha complex recruits components of the synaptic release machinery to adhesive proteins of the active zone. 相似文献
75.
Faraglia B Bonsignore A Scaldaferri F Boninsegna A Cittadini A Mancuso C Sgambato A 《Journal of cellular physiology》2005,202(2):478-482
In this study, the MCF-7 breast cancer cells that lack caspase-3 were transfected with a wild type (WT) or mutant caspase-3 cDNA. Expression of the WT, but not of the mutant, caspase-3 was associated with increased caspase activity and susceptibility to staurosporine (STS)-induced apoptosis. Both derivatives displayed inhibition of cell growth compared with vector control cells. Growth inhibition was associated with increased expression of the cyclin dependent kinase (CDK) inhibitor p27Kip1 in the WT, but not in the mutant caspase-3 expressing cells. Cyclin D1 expression level was not affected by caspase-3 expression. Phosphorylation of the Akt protein was decreased in both WT and mutant caspase transfected cells, although Akt expression level remained unchanged. These results suggest that caspase-3 might have biological functions independent of its protease activity and that its loss might contribute to tumor development by increasing the growth potential of cancer cells. 相似文献
76.
Yiwei Liu Maura Porta Jia Qin Jorge Ramos Alma Nani Thomas R. Shannon Michael Fill 《The Journal of general physiology》2010,135(1):15-27
The cardiac type 2 ryanodine receptor (RYR2) is activated by Ca2+-induced Ca2+ release (CICR). The inherent positive feedback of CICR is well controlled in cells, but the nature of this control is debated. Here, we explore how the Ca2+ flux (lumen-to-cytosol) carried by an open RYR2 channel influences its own cytosolic Ca2+ regulatory sites as well as those on a neighboring channel. Both flux-dependent activation and inhibition of single channels were detected when there were super-physiological Ca2+ fluxes (>3 pA). Single-channel results indicate a pore inhibition site distance of 1.2 ± 0.16 nm and that the activation site on an open channel is shielded/protected from its own flux. Our results indicate that the Ca2+ flux mediated by an open RYR2 channel in cells (∼0.5 pA) is too small to substantially regulate (activate or inhibit) the channel carrying it, even though it is sufficient to activate a neighboring RYR2 channel. 相似文献
77.
Daniel Filchtinski Alma Rüppel Ingrid R. Vetter Julia M. Shifman 《Journal of molecular biology》2010,399(3):422-435
Ras is a small GTP-binding protein that is an essential molecular switch for a wide variety of signaling pathways including the control of cell proliferation, cell cycle progression and apoptosis. In the GTP-bound state, Ras can interact with its effectors, triggering various signaling cascades in the cell. In the GDP-bound state, Ras looses its ability to bind to known effectors. The interaction of the GTP-bound Ras (RasGTP) with its effectors has been studied intensively. However, very little is known about the much weaker interaction between the GDP-bound Ras (RasGDP) and Ras effectors. We investigated the factors underlying the nucleotide-dependent differences in Ras interactions with one of its effectors, Raf kinase. Using computational protein design, we generated mutants of the Ras-binding domain of Raf kinase (Raf) that stabilize the complex with RasGDP. Most of our designed mutations narrow the gap between the affinity of Raf for RasGTP and RasGDP, producing the desired shift in binding specificity towards RasGDP. A combination of our best designed mutation, N71R, with another mutation, A85K, yielded a Raf mutant with a 100-fold improvement in affinity towards RasGDP. The Raf A85K and Raf N71R/A85K mutants were used to obtain the first high-resolution structures of RasGDP bound to its effector. Surprisingly, these structures reveal that the loop on Ras previously termed the switch I region in the RasGDP·Raf mutant complex is found in a conformation similar to that of RasGTP and not RasGDP. Moreover, the structures indicate an increased mobility of the switch I region. This greater flexibility compared to the same loop in RasGTP is likely to explain the natural low affinity of Raf and other Ras effectors to RasGDP. Our findings demonstrate that an accurate balance between a rigid, high-affinity conformation and conformational flexibility is required to create an efficient and stringent molecular switch. 相似文献
78.
Maile R Barnes CM Nielsen AI Meyer AA Frelinger JA Cairns BA 《Journal of immunology (Baltimore, Md. : 1950)》2006,176(11):6717-6726
Burn patients are immunocompromised yet paradoxically are able to effectively reject allogeneic skin grafts. Failure to close a massive burn wound leads to sepsis and multiple system organ failure. Immune suppression early (3 days) after burn injury is associated with glucocorticoid-mediated T cell apoptosis and anti-inflammatory cytokine responses. Using a mouse model of burn injury, we show CD8+ T cell hyperresponsiveness late (14 days) after burn injury. This is associated with a CD8+ T cell pro- and anti-inflammatory cytokine secretion profile, peripheral lymphopenia, and accumulation of a rapidly cycling, hyperresponsive memory-like CD8+CD44+ IL-7R- T cells which do not require costimulation for effective Ag response. Adoptive transfer of allospecific CD8+ T cells purified 14 days postburn results in enhanced allogeneic skin graft rejection in unburned recipient mice. Chemical blockade of glucocorticoid-induced lymphocyte apoptosis early after burn injury abolishes both the late homeostatic accumulation of CD8+ memory-like T cells and the associated enhanced proinflammatory CD8+ T cell response, but not the late enhanced CD8+ anti-inflammatory response. These data suggest a mechanism for the dynamic CD8+ T cell response following injury involving an interaction between activation, apoptosis, and cellular regeneration with broad clinical implications for allogeneic skin grafting and sepsis. 相似文献
79.
Mesenchymal stem cells inhibit generation and function of both CD34+-derived and monocyte-derived dendritic cells 总被引:15,自引:0,他引:15
Nauta AJ Kruisselbrink AB Lurvink E Willemze R Fibbe WE 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(4):2080-2087
Mesenchymal stem cells (MSCs) are not only able to evade the immune system, but they have also been demonstrated to exert profound immunosuppressive properties on T cell proliferation. However, their effect on the initiators of the immune response, the dendritic cells (DCs), are relatively unknown. In the present study, the effects of human MSCs on the differentiation and function of both CD34+ -derived DCs and monocyte-derived DCs were investigated. The presence of MSCs during differentiation blocked the differentiation of CD14+CD1a- precursors into dermal/interstitial DCs, without affecting the generation of CD1a+ Langerhans cells. In line with these observations, MSCs also completely prevented the generation of immature DCs from monocytes. The inhibitory effect of MSCs on DC differentiation was dose dependent and resulted in both phenotypical and functional modifications, as demonstrated by a reduced expression of costimulatory molecules and hampered capacity to stimulate naive T cell proliferation. The inhibitory effect of MSCs was mediated via soluble factors. Taken together, these data demonstrate that MSCs, next to the antiproliferative effect on T cells, have a profound inhibitory effect on the generation and function of both CD34+ -derived and monocyte-derived DCs, indicating that MSCs are able to modulate immune responses at multiple levels. 相似文献
80.
Marzorati M Alma A Sacchi L Pajoro M Palermo S Brusetti L Raddadi N Balloi A Tedeschi R Clementi E Corona S Quaglino F Bianco PA Beninati T Bandi C Daffonchio D 《Applied and environmental microbiology》2006,72(2):1467-1475
Flavescence dorée (FD) is a grapevine disease that afflicts several wine production areas in Europe, from Portugal to Serbia. FD is caused by a bacterium, "Candidatus Phytoplasma vitis," which is spread throughout the vineyards by a leafhopper, Scaphoideus titanus (Cicadellidae). After collection of S. titanus specimens from FD-contaminated vineyards in three different areas in the Piedmont region of Italy, we performed a survey to characterize the bacterial microflora associated with this insect. Using length heterogeneity PCR with universal primers for bacteria we identified a major peak associated with almost all of the individuals examined (both males and females). Characterization by denaturing gradient gel electrophoresis confirmed the presence of a major band that, after sequencing, showed a 97 to 99% identity with Bacteroidetes symbionts of the "Candidatus Cardinium hertigii" group. In addition, electron microscopy of tissues of S. titanus fed for 3 months on phytoplasma-infected grapevine plants showed bacterial cells with the typical morphology of "Ca. Cardinium hertigii." This endosymbiont, tentatively designated ST1-C, was found in the cytoplasm of previtellogenic and vitellogenic ovarian cells, in the follicle cells, and in the fat body and salivary glands. In addition, cell morphologies resembling those of "Ca. Phytoplasma vitis" were detected in the midgut, and specific PCR assays indicated the presence of the phytoplasma in the gut, fat body and salivary glands. These results indicate that ST1-C and "Ca. Phytoplasma vitis" have a complex life cycle in the body of S. titanus and are colocalized in different organs and tissues. 相似文献