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131.
Basal activation of the P2X7 ATP receptor elevates mitochondrial calcium and potential, increases cellular ATP levels, and promotes serum-independent growth 下载免费PDF全文
Adinolfi E Callegari MG Ferrari D Bolognesi C Minelli M Wieckowski MR Pinton P Rizzuto R Di Virgilio F 《Molecular biology of the cell》2005,16(7):3260-3272
P2X7 is a bifunctional receptor (P2X7R) for extracellular ATP that, depending on the level of activation, forms a cation-selective channel or a large conductance nonselective pore. The P2X7R has a strong proapoptotic activity but can also support growth. Here, we describe the mechanism involved in growth stimulation. Transfection of P2X7R increases resting mitochondrial potential (delta psi(mt)), basal mitochondrial Ca2+ ([Ca2+]mt), intracellular ATP content, and confers ability to grow in the absence of serum. These changes require a full pore-forming function, because they are abolished in cells transfected with a mutated P2X7R that retains channel activity but cannot form the nonselective pore, and depend on an autocrine/paracrine tonic stimulation by secreted ATP. On the other hand, sustained stimulation of P2X7R causes a delta psi(mt) drop, a large increase in [Ca2+]mt, mitochondrial fragmentation, and cell death. These findings reveal a hitherto undescribed mechanism for growth stimulation by a plasma membrane pore. 相似文献
132.
Prions are defined as infectious agents that comprise only proteins and are responsible for transmissible spongiform encephalopathies (TSEs)--fatal neurodegenerative diseases that affect humans and other mammals and include Creutzfeldt-Jacob disease in humans, scrapie in sheep and bovine spongiform encephalopathy in cattle. Prions have been proposed to arise from the conformational conversion of the cellular prion protein PrP(C) to a misfolded form termed PrP(Sc) that precipitates into aggregates and fibrils. The conversion process might be triggered by interaction of the infectious form with the cellular form or it might result from a mutation in the gene encoding PrP(C). Exactly how and where in the cell the interaction and the conversion of PrP(C) to PrP(Sc) occur, however, remain controversial. Recent studies have shed light on the intracellular trafficking of PrP(C), the role of protein mis-sorting and the cellular factors that are thought to be required for the conformational conversion of prion proteins. 相似文献
133.
Boccara M Mills CE Zeier J Anzi C Lamb C Poole RK Delledonne M 《The Plant journal : for cell and molecular biology》2005,43(2):226-237
Host cells respond to infection by generating nitric oxide (NO) as a cytotoxic weapon to facilitate killing of invading microbes. Bacterial flavohaemoglobins are well-known scavengers of NO and play a crucial role in protecting animal pathogens from nitrosative stress during infection. Erwinia chrysanthemi, which causes macerating diseases in a wide variety of plants, possesses a flavohaemoglobin (HmpX) whose function in plant pathogens has remained unclear. Here we show that HmpX consumes NO and prevents inhibition by NO of cell respiration, indicating a role in protection from nitrosative stress. Furthermore, infection of Saintpaulia ionantha plants with an HmpX-deficient mutant of E. chrysanthemi revealed that the lack of NO scavenging activity causes the accumulation of unusually high levels of NO in host tissue and triggers hypersensitive cell death. Introduction of the wild-type hmpX gene in an incompatible strain of Pseudomonas syringae had a dramatic effect on the hypersensitive cell death in soya bean cell suspensions, and markedly reduced the development of macroscopic symptoms in Arabidopsis thaliana plants. These observations indicate that HmpX not only protects against nitrosative stress but also attenuates host hypersensitive reaction during infection by intercepting NO produced by the plant for the execution of the hypersensitive cell death programme. 相似文献
134.
Salani S Donadoni C Rizzo F Bresolin N Comi GP Corti S 《Journal of cellular and molecular medicine》2012,16(7):1353-1364
Muscular dystrophies (MDs) are a heterogeneous group of inherited disorders characterized by progressive muscle wasting and weakness likely associated with exhaustion of muscle regeneration potential. At present, no cures or efficacious treatments are available for these diseases, but cell transplantation could be a potential therapeutic strategy. Transplantation of myoblasts using satellite cells or other myogenic cell populations has been attempted to promote muscle regeneration, based on the hypothesis that the donor cells repopulate the muscle and contribute to its regeneration. Embryonic stem cells (ESCs) and more recently induced pluripotent stem cells (iPSCs) could generate an unlimited source of differentiated cell types, including myogenic cells. Here we review the literature regarding the generation of myogenic cells considering the main techniques employed to date to elicit efficient differentiation of human and murine ESCs or iPSCs into skeletal muscle. We also critically analyse the possibility of using these cellular populations as an alternative source of myogenic cells for cell therapy of MDs. 相似文献
135.
Cardinale A Racaniello M Saladini S De Chiara G Mollinari C de Stefano MC Pocchiari M Garaci E Merlo D 《The Journal of biological chemistry》2012,287(4):2618-2631
Accumulation of DNA damage and deficiency in DNA repair potentially contribute to the progressive neuronal loss in neurodegenerative disorders, including Alzheimer disease (AD). In multicellular eukaryotes, double strand breaks (DSBs), the most lethal form of DNA damage, are mainly repaired by the nonhomologous end joining pathway, which relies on DNA-PK complex activity. Both the presence of DSBs and a decreased end joining activity have been reported in AD brains, but the molecular player causing DNA repair dysfunction is still undetermined. β-Amyloid (Aβ), a potential proximate effector of neurotoxicity in AD, might exert cytotoxic effects by reactive oxygen species generation and oxidative stress induction, which may then cause DNA damage. Here, we show that in PC12 cells sublethal concentrations of aggregated Aβ(25-35) inhibit DNA-PK kinase activity, compromising DSB repair and sensitizing cells to nonlethal oxidative injury. The inhibition of DNA-PK activity is associated with down-regulation of the catalytic subunit DNA-PK (DNA-PKcs) protein levels, caused by oxidative stress and reversed by antioxidant treatment. Moreover, we show that sublethal doses of Aβ(1-42) oligomers enter the nucleus of PC12 cells, accumulate as insoluble oligomeric species, and reduce DNA-PK kinase activity, although in the absence of oxidative stress. Overall, these findings suggest that Aβ mediates inhibition of the DNA-PK-dependent nonhomologous end joining pathway contributing to the accumulation of DSBs that, if not efficiently repaired, may lead to the neuronal loss observed in AD. 相似文献
136.
Susan SchlegelJohn Löfblom Chiara LeeAnna Hjelm Mirjam KlepschMarc Strous David DrewDirk Jan Slotboom Jan-Willem de Gier 《Journal of molecular biology》2012,423(4):648-659
Escherichia coli BL21(DE3) is widely used to overexpress proteins. In this overexpression host, the gene encoding the target protein is located on a plasmid and is under control of the T7 promoter, which is recognized exclusively by the T7 RNA polymerase (RNAP). The T7 RNAP gene is localized on the chromosome, and its expression is governed by the non-titratable, IPTG-inducible lacUV5 promoter. Recently, we constructed the Lemo21(DE3) strain, which allows improved control over the expression of genes from the T7 promoter. Lemo21(DE3) is a BL21(DE3) strain equipped with a plasmid harboring the gene encoding T7 lysozyme, an inhibitor of the T7 RNAP, under control of the exceptionally well-titratable rhamnose promoter. The overexpression yields of a large collection of membrane proteins in Lemo21(DE3) at different concentrations of rhamnose indicated that this strain may be very suitable for optimizing the production of membrane proteins. However, insight in the mechanism by which optimized expression yields are achieved in Lemo21(DE3) is lacking. Furthermore, whether the overexpressed proteins are suitable for functional and structural studies remains to be tested. Here, we show that in Lemo21(DE3), (i) the modulation of the activity of the T7 RNAP by the T7 lysozyme is key to optimizing the ratio of membrane proteins properly inserted in the cytoplasmic membrane to non-inserted proteins; (ii) maximizing the yields of membrane proteins is accompanied by reduction of the adverse effects of membrane protein overexpression, resulting in stable overexpression; and (iii) produced membrane proteins can be used for functional and structural studies. 相似文献
137.
Meacci E Cencetti F Donati C Nuti F Farnararo M Kohno T Igarashi Y Bruni P 《Biochimica et biophysica acta》2003,1633(3):133-142
The bioactive lipid sphingosine 1-phosphate (S1P) is known to exert powerful biological effects through the interaction with various members of the endothelial differentiation gene (EDG) receptor family, recently renamed S1P receptors. In the present study, evidence is provided that differentiation of C2C12 myoblasts into myotubes was accompanied by profound changes of EDG/S1P receptor expression. Indeed, in differentiated cells a significant increase of EDG3/S1P3 together with a large decrease of EDG5/S1P2 expression at mRNA as well as protein level was detected. Moreover, S1P was capable to initiate the signalling pathways downstream to cytosolic Ca(2+) increase in myotubes, similarly to that observed in myoblasts, whereas the signalling of the bioactive lipid to phospholipase D (PLD), but not that of bradykinin (BK) or lysophosphatidic acid (LPA), was found impaired in differentiated cells. Intriguingly, overexpression of EDG5/S1P2, but not EDG1/S1P1 or EDG3/S1P3, potentiated the efficacy of S1P to stimulate PLD, strongly suggesting a role for EDG5/S1P2 in the signalling to PLD. This view was also supported by the marked reduction of S1P-induced PLD activity in myoblasts loaded with antisense oligodeoxyribonucleotides (ODN) to EDG5/S1P2. Furthermore, overexpression of EDG5/S1P2 rescued the coupling of S1P signalling to PLD in C2C12 myotubes. Experimental evidence here provided supports the notion that EDG5/S1P2 plays a dominant role in the coupling of S1P to PLD in myoblasts and that the down-regulation of the receptor subtype is responsible for the specific uncoupling of S1P signalling to PLD in myotubes. 相似文献
138.
Roberto Gualtieri Chiara Campanella Piero Andreuccetti 《Development, growth & differentiation》1992,34(2):127-135
The K-pyroantimonate/OsO4 (PA) cytochemical method coupled with EGTA and X-ray microanalytical controls has been used to localize Ca2+ at egg activation in Discoglossus pictus eggs. The results show that: 1) the PA method is able to selectively localize Ca2+ pools mobilized by activating stimuli; 2) the smooth endoplasmic reticulum (SER) elements located in the animal dimple region, i.e. in the predetermined site of fertilization, are the first egg components labeled by precipitates; 3) a decreasing gradient of precipitates is present from the center beyond the boundaries of the dimple region; 4) precipitates are lacking in the remainder of the egg even at late times after activation.
The possibilities are discussed that a) SER is the major Ca2+ -releasing store at activation in Discoglossus , and b) the observed gradient of pyroantimonate-detected Ca2+ reflects an ionic Ca2+ gradient. 相似文献
The possibilities are discussed that a) SER is the major Ca
139.
140.
White Nicholas J Ashley Elizabeth A Recht Judith Delves Michael J Ruecker Andrea Smithuis Frank M Eziefula Alice C Bousema Teun Drakeley Chris Chotivanich Kesinee Imwong Mallika Pukrittayakamee Sasithon Prachumsri Jetsumon Chu Cindy Andolina Chiara Bancone Germana Hien Tran T Mayxay Mayfong Taylor Walter RJ von Seidlein Lorenz Price Ric N Barnes Karen I Djimdé Abdoulaye ter Kuile Feiko Gosling Roly Chen Ingrid Dhorda Mehul J Stepniewska Kasia Guérin Philippe Woodrow Charles J Dondorp Arjen M Day Nicholas PJ Nosten Francois H 《Malaria journal》2014,13(1):1-14