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排序方式: 共有139条查询结果,搜索用时 46 毫秒
11.
Iria Medraño-Fernandez Raquel Reyes Isabel Olazabal Elena Rodriguez Francisco Sanchez-Madrid Vassiliki A. Boussiotis Pedro A. Reche Carlos Cabañas Esther M. Lafuente 《Cellular and molecular life sciences : CMLS》2013,70(13):2395-2410
Phagocytosis mediated by the complement receptor CR3 (also known as integrin αMß2 or Mac-1) is regulated by the recruitment of talin to the cytoplasmic tail of the ß2 integrin subunit. Talin recruitment to this integrin is dependent on Rap1 activation. However, the mechanism by which Rap1 regulates this event and CR3-dependent phagocytosis remains largely unknown. In the present work, we examined the role of the Rap1 effector RIAM, a talin-binding protein, in the regulation of complement-mediated phagocytosis. Using the human myeloid cell lines HL-60 and THP-1, we determined that knockdown of RIAM impaired αMß2 integrin affinity changes induced by stimuli fMLP and LPS. Phagocytosis of complement-opsonized RBC particles, but not of IgG-opsonized RBC particles, was impaired in RIAM knockdown cells. Rap1 activation via EPAC induced by 8-pCPT-2′-O-Me-cAMP resulted in an increase of complement-mediated phagocytosis that was abrogated by knockdown of RIAM in HL-60 and THP-1 cell lines and in macrophages derived from primary monocytes. Furthermore, recruitment of talin to ß2 integrin during complement-mediated phagocytosis was reduced in RIAM knockdown cells. These results indicate that RIAM is a critical component of the phagocytosis machinery downstream of Rap1 and mediates its function by recruiting talin to the phagocytic complement receptors. 相似文献
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Kozyrev SV Abelson AK Wojcik J Zaghlool A Linga Reddy MV Sanchez E Gunnarsson I Svenungsson E Sturfelt G Jönsen A Truedsson L Pons-Estel BA Witte T D'Alfonso S Barizzone N Barrizzone N Danieli MG Gutierrez C Suarez A Junker P Laustrup H González-Escribano MF Martin J Abderrahim H Alarcón-Riquelme ME 《Nature genetics》2008,40(2):211-216
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Kraytsberg Y Kudryavtseva E McKee AC Geula C Kowall NW Khrapko K 《Nature genetics》2006,38(5):518-520
Using a novel single-molecule PCR approach to quantify the total burden of mitochondrial DNA (mtDNA) molecules with deletions, we show that a high proportion of individual pigmented neurons in the aged human substantia nigra contain very high levels of mtDNA deletions. Molecules with deletions are largely clonal within each neuron; that is, they originate from a single deleted mtDNA molecule that has expanded clonally. The fraction of mtDNA deletions is significantly higher in cytochrome c oxidase (COX)-deficient neurons than in COX-positive neurons, suggesting that mtDNA deletions may be directly responsible for impaired cellular respiration. 相似文献
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In Old World primates, TRIM5-alpha confers a potent block to human immunodeficiency virus type 1 (HIV-1) infection that acts after virus entry into cells. Cyclophilin A (CypA) binding to viral capsid protects HIV-1 from a similar activity in human cells. Among New World primates, only owl monkeys exhibit post-entry restriction of HIV-1 (ref. 1). Paradoxically, the barrier to HIV-1 in owl monkey cells is released by capsid mutants or drugs that disrupt capsid interaction with CypA. Here we show that knockdown of owl monkey CypA by RNA interference (RNAi) correlates with suppression of anti-HIV-1 activity. However, reintroduction of CypA protein to RNAi-treated cells did not restore antiviral activity. A search for additional RNAi targets unearthed TRIMCyp, an RNAi-responsive messenger RNA encoding a TRIM5-CypA fusion protein. TRIMCyp accounts for post-entry restriction of HIV-1 in owl monkeys and blocks HIV-1 infection when transferred to otherwise infectable human or rat cells. It seems that TRIMCyp arose after the divergence of New and Old World primates when a LINE-1 retrotransposon catalysed the insertion of a CypA complementary DNA into the TRIM5 locus. This is the first vertebrate example of a chimaeric gene generated by this mechanism of exon shuffling. 相似文献
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Optimal nitrogen-to-phosphorus stoichiometry of phytoplankton 总被引:12,自引:0,他引:12
Redfield noted the similarity between the average nitrogen-to-phosphorus ratio in plankton (N:P = 16 by atoms) and in deep oceanic waters (N:P = 15; refs 1, 2). He argued that this was neither a coincidence, nor the result of the plankton adapting to the oceanic stoichiometry, but rather that phytoplankton adjust the N:P stoichiometry of the ocean to meet their requirements through nitrogen fixation, an idea supported by recent modelling studies. But what determines the N:P requirements of phytoplankton? Here we use a stoichiometrically explicit model of phytoplankton physiology and resource competition to derive from first principles the optimal phytoplankton stoichiometry under diverse ecological scenarios. Competitive equilibrium favours greater allocation to P-poor resource-acquisition machinery and therefore a higher N:P ratio; exponential growth favours greater allocation to P-rich assembly machinery and therefore a lower N:P ratio. P-limited environments favour slightly less allocation to assembly than N-limited or light-limited environments. The model predicts that optimal N:P ratios will vary from 8.2 to 45.0, depending on the ecological conditions. Our results show that the canonical Redfield N:P ratio of 16 is not a universal biochemical optimum, but instead represents an average of species-specific N:P ratios. 相似文献
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Riassunto Si descrivono gli effetti teratogeni indotti nella coda del girino delBufo arenarum in uno stadio premetamorfosico, come conseguenza dell'impianto di cristalli di idrocarburi cancerigeni. Tanto il MC come il BP o il DMBA producono alette sopranumerarie che ripetono le strutture istologiche delle alette normali; ed inoltre il DMBA induce la formazione di una seconda notocorda parallela alla normale.
Career investigator of Argentine CNICT.
Fellow of Argentine CNICT. 相似文献
Career investigator of Argentine CNICT.
Fellow of Argentine CNICT. 相似文献
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