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991.
Lukáš Kubala Hana Kolářová Jan Víteček Silvie Kremserová Anna Klinke Denise Lau Anna L.P. Chapman Stephan Baldus Jason P. Eiserich 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Myeloperoxidase (MPO) is an abundant hemoprotein expressed by neutrophil granulocytes that is recognized to play an important role in the development of vascular diseases. Upon degranulation from circulating neutrophil granulocytes, MPO binds to the surface of endothelial cells in an electrostatic-dependent manner and undergoes transcytotic migration to the underlying extracellular matrix (ECM). However, the mechanisms governing the binding of MPO to subendothelial ECM proteins, and whether this binding modulates its enzymatic functions are not well understood.Methods
We investigated MPO binding to ECM derived from aortic endothelial cells, aortic smooth muscle cells, and fibroblasts, and to purified ECM proteins, and the modulation of these associations by glycosaminoglycans. The oxidizing and chlorinating potential of MPO upon binding to ECM proteins was tested.Results
MPO binds to the ECM proteins collagen IV and fibronectin, and this association is enhanced by the pre-incubation of these proteins with glycosaminoglycans. Correspondingly, an excess of glycosaminoglycans in solution during incubation inhibits the binding of MPO to collagen IV and fibronectin. These observations were confirmed with cell-derived ECM. The oxidizing and chlorinating potential of MPO was preserved upon binding to collagen IV and fibronectin; even the potentiation of MPO activity in the presence of collagen IV and fibronectin was observed.Conclusions
Collectively, the data reveal that MPO binds to ECM proteins on the basis of electrostatic interactions, and MPO chlorinating and oxidizing activity is potentiated upon association with these proteins.General significance
Our findings provide new insights into the molecular mechanisms underlying the interaction of MPO with ECM proteins. 相似文献992.
993.
Xiangling Yang William W. Du Haoran Li Fengqiong Liu Anna Khorshidi Zina Jeyapalan Rutnam Burton B. Yang 《Nucleic acids research》2013,41(21):9688-9704
MicroRNAs (miRNA) precursor (pre-miRNA) molecules can be processed to release a miRNA/miRNA* duplex. In the canonical model of miRNA biogenesis, one strand of the duplex is thought to be the biologically active miRNA, whereas the other strand is thought to be inactive and degraded as a carrier or passenger strand called miRNA* (miRNA star). However, recent studies have revealed that miRNA* strands frequently play roles in the regulatory networks of miRNA target molecules. Our recent study indicated that miR-17 transgenic mice could abundantly express both the mature miR-17-5p and the passenger strand miR-17-3p. Here, we showed that miR-17 enhanced prostate tumor growth and invasion by increasing tumor cell proliferation, colony formation, cell survival and invasion. miRNA target analysis showed that both miR-17-5p and miR-17-3p repressed TIMP metallopeptidase inhibitor 3 (TIMP3) expression. Silencing with small interfering RNA against TIMP3 promoted cell survival and invasion. Ectopic expression of TIMP3 decreased cell invasion and cell survival. Our results demonstrated that mature miRNA can function coordinately with its passenger strand, enhancing the repressive ability of a miRNA by binding the same target. Within an intricate regulatory network, this may be among the mechanisms by which miRNA can augment their regulatory capacity. 相似文献
994.
995.
Carla Bazzicalupi Marta Ferraroni Anna Rita Bilia Francesca Scheggi Paola Gratteri 《Nucleic acids research》2013,41(1):632-638
The first crystal structure of human telomeric DNA in complex with the natural alkaloid berberine, produced by different plant families and used in folk medicine for millennia, was solved by X-ray diffraction method. The G-quadruplex unit features all-parallel strands. The overall folding assumed by DNA is the same found in previously reported crystal structures. Similarly to previously reported structures the ligand molecules were found to be stacked onto the external 5′ and 3′-end G-tetrads. However, the present crystal structure highlighted for the first time, the presence of two berberine molecules in the two binding sites, directly interacting with each tetrad. As a consequence, our structural data point out a 2:1 ligand to G-tetrad molar ratio, which has never been reported before in a telomeric intramolecular quadruplex structure. 相似文献
996.
997.
Background and Aims
Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased temperature compared with the responses of leaf gas exchange and leaf water status.Methods
Two controlled-environment growth chamber experiments were conducted with soybean to measure Kleaf, stomatal conductance (gs) and photosynthesis (A) during growth at elevated [CO2] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO2] (FACE) and canopy warming.Key results
In chamber studies, Kleaf did not acclimate to growth at elevated [CO2], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect Kleaf, although gs and A showed significant but inconsistent decreases. The lack of response of Kleaf to growth at increased [CO2] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility.Conclusions
Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although gs responded to [CO2] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change. 相似文献998.
Anna M. Romaní Stefano Amalfitano Joan Artigas Stefano Fazi Sergi Sabater Xisca Timoner Irene Ylla Annamaria Zoppini 《Hydrobiologia》2013,719(1):43-58
River and stream biofilms in mediterranean fluvial ecosystems face both extreme seasonality as well as arrhythmic fluctuations. The hydrological extremes (droughts and floods) impose direct changes in water availability but also in the quantity and quality of organic matter and nutrients that sustain the microbial growth. This review analyzes how these ecological pulses might determine unique properties of biofilms developing in mediterranean streams. The paper brings together data from heterotrophic and autotrophic community structure, and extracellular enzyme activities in biofilms in mediterranean streams. Mediterranean stream biofilms show higher use of peptides during the favorable period for epilithic algae development (spring), and preferential use of cellulose and hemicellulose in autumn as a response to allochthonous input. The drying process causes the reduction in bacterial production and chlorophyll biomass, but the rapid recovery of both autotrophs and heterotrophs with rewetting indicates their adaptability to fluctuations. Bacteria surviving the drought are mainly associated with sediment and leaf litter which serve as “humid refuges”. Some algae and cyanobacteria show resistant strategies to cope with the drought stress. The resistance to these fluctuations is strongly linked to the streambed characteristics (e.g., sediment grain size, organic matter accumulation, nutrient content). 相似文献
999.
Barbara Pietrzak Anna Bednarska Magdalena Markowska Maciej Rojek Ewa Szymanska Miroslaw Slusarczyk 《Hydrobiologia》2013,715(1):125-134
The combined effect of external environment and energy allocation strategy of the organism on longevity can be exceptional. In a cold oligotrophic fishless habitat, individual Daphnia can live for over a year, several times the usual Daphnia lifespan. This extreme lifespan is in part a consequence of the overwintering strategy which includes storing resources and delaying reproduction until another spring. Yet, contrasting strategies may be applied by Daphnia, resulting in over twofold differences in lifespan within a single habitat. We identify physiological mechanisms mediating such differences in longevity in closely related Daphnia of two lineages coexisting within a high altitude lake, testing the predictions that long-lived animals stay in colder waters and have lower metabolic rates, irrespective of temperature. Vertical distribution of the animals was assessed during three summer stratification seasons, and metabolic activity was measured as oxygen consumption and RNA:DNA ratio. The results not only support our predictions but also reveal that habitat choice is dependent on reproductive status rather than genotype. The young individuals of the overwintering lineage may delay reproduction in part by staying in colder waters than the reproducing adults, which together with low intrinsic metabolic rates may underlie the longevity of Daphnia of this lineage. 相似文献
1000.
Noureddine Zebda Yufeng Tian Xinyong Tian Grzegorz Gawlak Katherine Higginbotham Albert B. Reynolds Anna A. Birukova Konstantin G. Birukov 《The Journal of biological chemistry》2013,288(25):18290-18299
p120-catenin is a multidomain intracellular protein, which mediates a number of cellular functions, including stabilization of cell-cell transmembrane cadherin complexes as well as regulation of actin dynamics associated with barrier function, lamellipodia formation, and cell migration via modulation of the activities of small GTPAses. One mechanism involves p120 catenin interaction with Rho GTPase activating protein (p190RhoGAP), leading to p190RhoGAP recruitment to cell periphery and local inhibition of Rho activity. In this study, we have identified a stretch of 23 amino acids within the C-terminal domain of p120 catenin as the minimal sequence responsible for the recruitment of p190RhoGAP (herein referred to as CRAD; catenin-RhoGAP association domain). Expression of the p120-catenin truncated mutant lacking the CRAD in endothelial cells attenuated effects of barrier protective oxidized phospholipid, OxPAPC. This effect was accompanied by inhibition of membrane translocation of p190RhoGAP, increased Rho signaling, as well as suppressed activation of Rac1 and its cytoskeletal effectors PAK1 (p21-activated kinase 1) and cortactin. Expression of p120 catenin-truncated mutant lacking CRAD also delayed the recovery process after thrombin-induced endothelial barrier disruption. Concomitantly, RhoA activation and downstream signaling were sustained for a longer period of time, whereas Rac signaling was inhibited. These data demonstrate a critical role for p120-catenin (amino acids 820–843) domain in the p120-catenin·p190RhoGAP signaling complex assembly, membrane targeting, and stimulation of p190RhoGAP activity toward inhibition of the Rho pathway and reciprocal up-regulation of Rac signaling critical for endothelial barrier regulation. 相似文献