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61.
Binding of B‐cell maturation antigen to B‐cell activating factor induces survival of multiple myeloma cells by activating Akt and JNK signaling pathways
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Xianjuan Shen Yuehua Guo Jing Qi Wei Shi Xinhua Wu Shaoqing Ju 《Cell biochemistry and function》2016,34(2):104-110
B‐cell maturation antigen (BCMA) is expressed on normal and malignant plasma cells and represents a potential target for therapeutic intervention. In this study, we characterized the mechanism underlying the protein kinase B (Akt) and c‐Jun N‐terminal kinase (JNK) pathways and BCMA interactions in regulating multiple myeloma (MM) cell survival. It was found that the expression levels of B cell‐activating factor (BAFF) and BCMA were increased in MM cells as compared with those in normal controls. The proliferation of U266 cells was induced by recombinant human BAFF (rhBAFF) and could also be decreased by BCMA siRNA. The expression of Bcl‐2 protein was up‐regulated, and Bax protein was down‐regulated after rhBAFF treatment, which could be reversed by BCMA siRNA. Similarly, the protein p‐JNK and p‐Akt were activated by rhBAFF and could be changed by BCMA siRNA. In addition, the BCMA mRNA and protein expression levels were decreased after treatment with Akt and JNK pathway inhibitors. These results suggest that Akt and JNK pathways are involved in the regulation of BCMA. A novel BAFF/BCMA signalling pathway in MM may be a new therapeutic target for MM. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
62.
Dynamic Light Regulation of Photosynthesis (A Review) 总被引:9,自引:7,他引:2
Regulatory reactions providing the photosynthetic apparatus with the ability to respond to variations of irradiance by changes in activities of the light and the dark stages of photosynthesis within a time range of seconds and minutes are considered in the review. At the light stage, such reactions are related to the changes in both distribution of light energy between two photosystems and probability of nonphotochemical dissipation of absorbed quanta in PSI and PSII. These regulatory reactions operate in a negative feedback mode, thus avoiding overreduction of electron transport chain and minimizing the probability of generation of reactive oxygen species. The crucial role in preventing the generation of reactive oxygen species belongs to dynamic regulation of electron transport activity despite the presence of complex system of their detoxification in chloroplasts. In dark reactions of Calvin cycle, the regulatory responses involve a positive feedback principle being related to redox regulation of activities of several enzymes, which is sensitive to the reduction status of PSI acceptor side. The complex of regulatory reactions based on negative and positive feedback principles provides prolonged functioning of a chloroplast and high stability of photosynthetic activity under various light conditions. 相似文献
63.
Dominique Grizeau Lan Anh Bui Catherine Dupré Jack Legrand 《Critical reviews in biotechnology》2016,36(4):607-618
Over the last decades, production of microalgae and cyanobacteria has been developed for several applications, including novel foods, cosmetic ingredients and more recently biofuel. The sustainability of these promising developments can be hindered by some constraints, such as water and nutrient footprints. This review surveys data on N2-fixing cyanobacteria for biomass production and ways to induce and improve the excretion of ammonium within cultures under aerobic conditions. The nitrogenase complex is oxygen sensitive. Nevertheless, nitrogen fixation occurs under oxic conditions due to cyanobacteria-specific characteristics. For instance, in some cyanobacteria, the vegetative cell differentiation in heterocyts provides a well-adapted anaerobic microenvironment for nitrogenase protection. Therefore, cell cultures of oxygenic cyanobacteria have been grown in laboratory and pilot photobioreactors (Dasgupta et al., 2010; Fontes et al., 1987; Moreno et al., 2003; Nayak & Das, 2013). Biomass production under diazotrophic conditions has been shown to be controlled by environmental factors such as light intensity, temperature, aeration rate, and inorganic carbon concentration, also, more specifically, by the concentration of dissolved oxygen in the culture medium. Currently, there is little information regarding the production of extracellular ammonium by heterocytous cyanobacteria. This review compares the available data on maximum ammonium concentrations and analyses the specific rate production in cultures grown as free or immobilized filamentous cyanobacteria. Extracellular production of ammonium could be coupled, as suggested by recent research on non-diazotrophic cyanobacteria, to that of other high value metabolites. There is little information available regarding the possibility for using diazotrophic cyanobacteria as cellular factories may be in regard of the constraints due to nitrogen fixation. 相似文献
64.
Whole cells of Chlorella vulgaris and Clostridium butyricum were co-immobilized in 2% agar gel. NADP was suitable as an electron carrier. The rate of hydrogen evolution increased with increasing NADP concentration. The optimum conditions for hydrogen evolution were pH 7.0 and 37°C. The immobilized C. vulgaris-NADP-immobilized Cl. butyricum system continuously evolved hydrogen at a rate of 0.29–1.34 μmol/h per mg Chl for 6 days. On the other hand, the system without NADP evolved only a trace amount of hydrogen. 相似文献
65.
66.
Elli Kohen Cahide Kohen Joseph G. Hirschberg Alain W. Wouters Bo Thorell 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,720(4):420-424
A microspectrofluorimetric study is made of the influence of dimethylnitrosamine on NADP reduction, following sequential microinjections into the same L cell, of two substrates: (1) isocitrate, with activity of isocitrate dehydrogenase both in the extramitochondrial and intramitochondrial compartments, (2) 6-phosphogluconate, with activity of the dehydrogenase in the extramitochondrial compartment. In control L cells a two-step reduction of NAD(P) is obtained followed by relatively slow reoxidation. In the minutes which follow addition of carcinogen, e.g., dimethylnitrosamine, to the cell medium the isocitrate and 6-phosphogluconate-induced transient NADP reoxidation is decreased in magnitude compared to control, while the rate constant of NADPH reoxidation is considerably accelerated, possibly due to requirements at the level of the microsomal metabolizing system. Observations within the first hour of carcinogen addition suggest an interesting system for evaluating the immediate actions of carcinogens at extranuclear sites: i.e., a comparative study of NADP reduction-reoxidation rate constants via injection of substrates for extra- vs. intramitochondrial pathways. 相似文献
67.
L. Chaerle F. De Boever M. Van Montagu & D. Van Der Straeten 《Plant, cell & environment》2001,24(1):15-25
Pending cell death was visualized by thermographic imaging in bacterio‐opsin transgenic tobacco plants. Cell death in these plants was characterized by a complex lesion phenotype. Isolated cell death lesions were preceded by a colocalized thermal effect, as previously observed at sites infected by tobacco mosaic virus (TMV) ( Chaerle et al. 1999 Nature Biotechnology 17, 813–816). However, in most cases, a coherent front of higher temperature, trailed by cell death, initiated at the leaf base and expanded over the leaf lamina. In contrast to the homogenous thermal front, cell death was first visible close to the veins, and subsequently appeared as discrete spots on the interveinal tissue, as cell death spread along the veins. Regions with visible cell death had a lower temperature because of water evaporation from damaged cells. In analogy with previous observations on the localized tobacco–TMV interaction ( Chaerle et al. 1999 ), the kinetics of thermographic and continuous gas exchange measurements indicated that stomatal closure preceded tissue collapse. Localized spontaneous cell death could also be presymptomatically visualized in the Arabidopsis lsd2 mutant. 相似文献
68.
Early Inhibition of Acetylcholinesterase and Choline Acetyltransferase Activity in Herpes simplex Virus Type 1 Infection of PC12 Cells 总被引:1,自引:0,他引:1
Abstract: Early in the course of productive Herpes simplex virus type 1 (HSV-1) infection of PC12 cells, activities of both acetylcholinesterase (AChE) and choline acetyltransferase (CAT) fell. Studies using metabolic inhibitors and a temperature-sensitive mutant of the virus suggested that the decline in activities of both enzymes was associated with events occurring early in the replicative cycle related to expression of the immediate-early (α) group of viral polypeptides. HSV-1 gene products thus may alter specialized cell functions well before the production of viral progeny and initiation of cell lysis. The early clinical manifestations of nervous system viral infection may reflect focal metabolic disturbance rather than, or in addition to, simple cell death. 相似文献
69.
P. Sauvage P. Lopez-Saura M.-A. Leroy-Houyet P. Tulkens A. Trouet 《生物化学与生物物理学报:生物膜》1981,644(1):41-52
The plasma membrane of the hepatoma cell line, HTC cells, has been characterized and purified by cell fractionation techniques. In the absence of true 5′-nucleotidase in HTC cells, alkaline phosphodiesterase I has been used as a marker enzyme, following conclusions gained from differential and isopycnic centrifugation studies (Lopez Saura, P., Trouet A. and Tulkens P. (1978) Biochim. Biophys. Acta 543, 430–449). To confirm this localization, HTC cells were exposed to anti-plasma membrane IgG at 4°C and fractionated. Alkaline phosphodiesterase I and IgG showed super imposable distribution patterns in linear sucrose gradients. Alkaline phosphodiesterase I is, however, only poorly resolved from enzyme markers of other organelles, especially NADPH-cytochrome reductase (endoplasmic reticulum) and galactosyltransferase (Golgi complex). Maximal purification from the homogenate is only 13-fold, on a protein basis, even when using a microsomal fraction (67 and 13% of alkaline phosphodiesterase I and protein, respectively) as the starting material. Improved resolution can be obtained after the addition of small quantities of digitonin (equimolar with respect to the cholesterol content). Digitonin increases the buoyant density of alkaline phosphodiesterase I by approx. 0.05 g/cm3, whereas the buoyant densities of galactosyltransferase and NADPH-cytochrome reductase are increased only by 0.03 and 0.015 g/cm3, respectively. Accordingly, a procedure has been designed which yields a fraction containing 22.8% of alkaline phosphodiesterase I with a purification of 21-fold on a protein basis. The content of NADPH-cytochrome reductase and galactosyltransferase is 1.2 and 2.1%, respectively. Electron microscopy shows smooth surface membrane elements and vesicles, with only occasional other recognizable elements. 相似文献
70.
In the frog intestine, both in vitro and in vivo, experiments were carried out in order to increase knowledge of the mechanism of sugar exit across the basolateral membrane of the enterocyte. The frog intestine was chosen because it lacks crypt cells and, consequently, any external fluid circuit mechanism during sugar transport can be avoided. Therefore, the sugar concentration in the absorbate collected on the serosal side is likely to be similar to that present underneath the basolateral membrane of the enterocyte. Under this condition, cell and absorbate sugar concentrations are similar; yet there is a concomitant net transintestinal sugar transport. Moreover, in in vivo experiments a net transintestinal sugar transport takes place even against a concentration difference. These results suggest that sugar exit across the basolateral membrane is not simply due to a chemically facilitated diffusion. 相似文献