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排序方式: 共有119条查询结果,搜索用时 15 毫秒
81.
82.
Preservation of NADH ubiquinone-oxidoreductase activity by Src kinase-mediated phosphorylation of NDUFB10 总被引:1,自引:0,他引:1
Hebert-Chatelain E Jose C Gutierrez Cortes N Dupuy JW Rocher C Dachary-Prigent J Letellier T 《Biochimica et biophysica acta》2012,1817(5):718-725
The tyrosine kinase Src is upregulated in several cancer cells. In such cells, there is a metabolic reprogramming elevating aerobic glycolysis that seems partly dependent on Src activation. Src kinase was recently shown to be targeted to mitochondria where it modulates mitochondrial bioenergetics in non-proliferative tissues and cells. The main goal of our study was to determine if increased Src kinase activity could also influence mitochondrial metabolism in cancer cells (143B and DU145 cells). We have shown that 143B and DU145 cells produce most of the ATP through glycolysis but also that the inhibition of OXPHOS led to a significant decrease in proliferation which was not due to a decrease in the total ATP levels. These results indicate that a more important role for mitochondria in cancer cells could be ensuring mitochondrial functions other than ATP production. This study is the first to show a putative influence of intramitochondrial Src kinase on oxidative phosphorylation in cancer cells. Indeed, we have shown that Src kinase inhibition led to a decrease in mitochondrial respiration via a specific decrease in complex I activities (NADH-ubiquinone oxidoreductase). This decrease is associated with a lower phosphorylation of the complex I subunit NDUFB10. These results suggest that the preservation of complex I function by mitochondrial Src kinase could be important in the development of the overall phenotype of cancer. 相似文献
83.
84.
El Medawar L Rocher P Hornez JC Traisnel M Breme J Hildebrand HF 《Biomolecular engineering》2002,19(2-6):153-160
Orthodontic arcs and wires are mostly realised from alloys and constitute the motor of dental shifting. Ti-base alloys rapidly replaced the formerly used stainless steel wires due to their excellent corrosion resistance, their high mechanical characteristics and their increased biocompatibility. NiTiNOL shape memory alloys add to these advantages their ability of deforming force. NiTiNOL, highly pure Nickel (hp-Ni) and commercially pure titanium (cp-Ti) were tested by electrochemical assays in artificial saliva and in vitro biological tests with L132 cells and HEPM cells. All tests gave concordant results: the electrochemical assays, the proliferation test, the colony forming method, and the inflammatory test clearly show, that nickel is a corrosive and a cytotoxic material. Ti and NiTiNOL are cytocompatible and in particular corrosion resistant. No significant differences are observed for both materials on the electrochemical and the biological level as well. The NiTiNOL shape memory alloy is a master trump for dental practitioners to repair occlusal defects by shifting teeth under optimal biological conditions. In spite of its high Ni-content, it is biocompatible. It considerably reduces the tune of therapeutic treatment, facilitate the occlusal concept and leads to a result of high clinical quality. 相似文献
85.
Intracellular Ca(2+) stores in chemoreceptor cells of the rabbit carotid body: significance for chemoreception 总被引:1,自引:0,他引:1
Vicario I Obeso A Rocher A López-Lopez JR González C 《American journal of physiology. Cell physiology》2000,279(1):C51-C61
Thenotion that intracellular Ca2+ (Cai2+)stores play a significant role in the chemoreception process inchemoreceptor cells of the carotid body (CB) appears in the literaturein a recurrent manner. However, the structural identity of theCa2+ stores and their real significance in the function ofchemoreceptor cells are unknown. To assess the functional significanceof Cai2+ stores in chemoreceptor cells, we havemonitored 1) the release of catecholamines (CA) from thecells using an in vitro preparation of intact rabbit CB and2) the intracellular Ca2+ concentration([Ca2+]i) using isolated chemoreceptor cells;both parameters were measured in the absence or the presence of agentsinterfering with the storage of Ca2+. We found thatthreshold [Ca2+]i for high extracellularK+ (Ke+) to elicit a release response is250 nM. Caffeine (10-40 mM), ryanodine (0.5 µM), thapsigargin(0.05-1 µM), and cyclopiazonic acid (10 µM) did not alter thebasal or the stimulus (hypoxia, high Ke+)-inducedrelease of CA. The same agents produced Cai2+transients of amplitude below secretory threshold; ryanodine (0.5 µM), thapsigargin (1 µM), and cyclopiazonic acid (10 µM) did notalter the magnitude or time course of the Cai2+responses elicited by high Ke+. Several potentialactivators of the phospholipase C system (bethanechol, ATP, andbradykinin), and thereby of inositol 1,4,5-trisphosphate receptors,produced minimal or no changes in [Ca2+]i anddid not affect the basal release of CA. It is concluded that, in therabbit CB chemoreceptor cells, Cai2+ stores do not playa significant role in the instant-to-instant chemoreception process. 相似文献
86.
L C Uhteg D R Salomon L L Rocher J W Kupiec-Weglinski J L Araujo M F Rubin N L Tilney C B Carpenter 《Journal of immunology (Baltimore, Md. : 1950)》1985,135(3):1800-1805
Lymphocytes from spleen, peripheral blood, thymus, and lymph node of naive rats, nonimmunosuppressed recipients of MHC-incompatible heart grafts, and cyclosporine-treated recipients of MHC-incompatible heart grafts were tested for their ability to augment or suppress proliferation of naive cells in an in vitro MLR co-culture assay. Rats treated with cyclosporine for only 7 days maintained their grafts indefinitely. Potent suppressor activity was found in the peripheral blood and spleen of adult naive rats. In untreated engrafted rats, increased suppressor activity was found 1 wk after transplantation and increased helper activity 2 wk after transplantation. In contrast, subnormal helper and suppressor activity was found in cyclosporine-treated rats 1 wk after transplantation. Subsequently, suppressor activity peaked at 2 to 3 wk and helper activity at 4 wk after transplantation. Beyond 5 wk, the cyclosporine-treated rat was indistinguishable from naive ungrafted rats. Two types of suppressor activity were identified that differed in buoyant density and cyclophosphamide sensitivity. Neither suppressor activity demonstrated antigen specificity. These data suggest that one role of cyclosporine in this rat model is to delay the initial helper mechanisms until generalized suppressor activity is operable. The increased antigen-nonspecific activity is only transient, presumably until the final antigen-specific mechanisms become operative. 相似文献
87.
Ivan J. Delgado Zhaohong Wang Amy de Rocher Kenneth Keegstra Natasha V. Raikhel 《Plant physiology》1998,116(4):1339-1350
A reversibly glycosylated polypeptide
from pea (Pisum sativum) is thought to have a role in
the biosynthesis of hemicellulosic polysaccharides. We have
investigated this hypothesis by isolating a cDNA clone encoding a
homolog of Arabidopsis
thaliana,
Reversibly Glycosylated
Polypeptide-1 (AtRGP1), and preparing antibodies against
the protein encoded by this gene. Polyclonal antibodies detect homologs
in both dicot and monocot species. The patterns of expression and
intracellular localization of the protein were examined. AtRGP1 protein
and RNA concentration are highest in roots and suspension-cultured
cells. Localization of the protein shows it to be mostly soluble but
also peripherally associated with membranes. We confirmed that AtRGP1
produced in Escherichia coli could be reversibly
glycosylated using UDP-glucose and UDP-galactose as substrates.
Possible sites for UDP-sugar binding and glycosylation are discussed.
Our results are consistent with a role for this reversibly glycosylated
polypeptide in cell wall biosynthesis, although its precise role is
still unknown.The primary cell wall of dicot plants is laid down by young cells
prior to the cessation of elongation and secondary wall deposition.
Making up to 90% of the cell''s dry weight, the extracellular matrix
is important for many processes, including morphogenesis, growth,
disease resistance, recognition, signaling, digestibility, nutrition,
and decay. The composition of the cell wall has been extensively
described (Bacic et al., 1988; Levy and Staehelin, 1992; Zablackis et
al., 1995), and yet many questions remain unanswered regarding the
synthesis and interaction of these components to provide cells with a
functional wall (Carpita and Gibeaut, 1993; Carpita et al., 1996).Heteropolysaccharide biosynthesis can be divided into four steps: (a)
chain or backbone initiation, (b) elongation, (c) side-chain addition,
and (d) termination and extracellular deposition (Waldron and Brett,
1985). The similarity between various polysaccharide backbones leads to
the prediction that the synthesizing machinery would be conserved
between them. For example, the backbone of xyloglucan polymers, β-1,4
glucan, can be synthesized independently of or concurrently with
side-chain addition (Campbell et al., 1988; White et al., 1993), and
this polymer and the chains that make up cellulose are identical. The
later addition of side chains to xyloglucan are catalyzed by specific
transferases (Kleene and Berger, 1993) such as xylosyltransferase
(Campbell et al., 1988), galactosyltransferase, and fucosyltransferase
(Faïk et al., 1997), all of which are localized to the Golgi
compartment (Brummell et al., 1990; Driouich et al., 1993; Staehelin
and Moore, 1995).The enzymes involved in wall biosynthesis have been recalcitrant to
isolation (Carpita et al., 1996; Albersheim et al., 1997). Only
recently has the first gene encoding putative cellulose biosynthetic
enzymes, celA, been isolated from cotton (Gossypium
hirsutum) and rice (Oryza sativa; Pear et al.,
1996).During studies of polysaccharide synthesis in pea (Pisum
sativum) Golgi membranes, Dhugga et al. (1991) identified a 41-kD
protein doublet that they suggested was involved in polysaccharide
synthesis. The authors showed that this protein could be glycosylated
by radiolabeled UDP-Glc but that this labeling could be reversibly
competed with by unlabeled UDP-Glc, UDP-Xyl, and UDP-Gal, the sugars
that make up xyloglucan (Hayashi, 1989). The 41-kD protein was named
PsRGP1 (P.
sativum Reversibly
Glycosylated Polypeptide-1; Dhugga et al.,
1997). Furthermore, the conditions that stimulate or inhibit
Golgi-localized β-glucan synthase activity are the same conditions
that stimulate or inhibit the glycosylation of PsRGP1 (Dhugga et al.,
1991). To address the role of this protein in polysaccharide synthesis,
the authors purified the polypeptides and obtained the sequences from
tryptic peptides (Dhugga and Ray, 1994). Antibodies raised against
PsRGP1 showed that it is soluble and localized to the plasma membrane
(Dhugga et al., 1991) and Golgi compartment (Dhugga et al., 1997). In
addition to its Golgi localization, the steady-state glycosylation of
PsRGP1 is approximately 10:7:3 (UDP-Glc:-Xyl:-Gal), which is similar to
the typical sugar composition of xyloglucan (1.0:0.75:0.25; Dhugga et
al., 1997).We were interested in studying various aspects of cell wall metabolism,
including the synthesis of polysaccharides and their delivery to the
cell wall. Studies in pea have shown that a 41-kD protein may be
involved in cell wall polysaccharide synthesis, possibly that of
xyloglucan (Dhugga et al., 1997). Here we report the characterization
of AtRGP1 (Arabidopsis
thaliana Reversibly
Glycosylated Polypeptide-1), a soluble protein
that can also be found weakly associated with membrane fractions, most
likely the Golgi fraction. The reversible nature of the glycosylation
of this Arabidopsis homolog by the substrates used to make
polysaccharides (nucleotide sugars) suggests a possible role for AtRGP1
in polysaccharide biosynthesis. 相似文献
88.
Towards a reduction in excess sludge production in activated sludge processes: biomass physicochemical treatment and biodegradation 总被引:15,自引:0,他引:15
M. Rocher G. Goma A. Pilas Begue L. Louvel J. L. Rols 《Applied microbiology and biotechnology》1999,51(6):883-890
To decrease activated sludge production, microbial cell lysis can be amplified to enhance cryptic growth (biomass growth
on lysates). Cell breakage techniques (thermal, alkaline, acid) were studied to generate Alcaligenes eutrophus and sludge lysates and to evaluate their biodegradability. Gentle treatment conditions produced the best results. Complete
cell deactivation was obtained for temperatures higher than 55 °C. The release kinetics were similar for temperatures varying
from 60 °C to 100 °C. A 20-min incubation was suitable for reaching 80% of the maximum releasable carbon. In thermal-chemical
hydrolysis, NaOH was the most efficient for inducing cell lysis. Carbon release was a two-step process. First an immediate
release occurred, which was of the same order of magnitude for A. eutrophus and sludge [100–200 mg dissolved organic C (DOC) g total suspended solids (TSS)−1], followed by a post-treatment release. The second step was virtually equivalent to the first for sludge, and weaker for
A. eutrophus (<50 mg DOC g TSS−1). The biodegradability of the soluble fraction, both the immediate and the post-treatment carbon release, was investigated.
The optimal degradation yield, obtained with sludge cells, reached 55% after 48 h of incubation and 80% after 350 h. The most
consistent lysis and biodegradation results occurred at pH 10 and 60 °C after a 20-min incubation.
Received: 30 October 1998 / Received revision: 16 February 1999 / Accepted: 20 February 1999 相似文献
89.
Kernec Florence Nadal Lydie Rocher Chantal Mateo Philippe de Certaines Jacques Le Rumeur Elisabeth Le Rumeur Elisabeth 《Molecular and cellular biochemistry》1999,194(1-2):165-171
Mitochondrial creatine kinase (Mi-CK) function in viable mitochondria from developing rat skeletal muscle was assessed both by polarographic measurements of creatine-induced respiration and 31P NMR spectroscopy measurements of phosphocreatine (PCr) synthesis. Creatine-induced respiration was observed in very young rats and increased by 50% to 35 days of age. PCr synthesis was present in 7 day old animals and increased by 300% reaching levels measured in 35 day and adult muscle. Unlike reports showing Mi-CK enzymatic activities but no mitochondrial function in several situations, a concomitant progression of enzymatic activity and mitochondrial function was evidenced during the developmental stages of skeletal muscle Mi-CK in altricious animals. These results correlated with the progressive pattern of muscle differentiation during development of motricity in such animals. The observation that Mi-CK is functional in skeletal muscle mitochondria very early after birth, strongly favors the notion that adaptations in skeletal muscle of Mi-CK knock-out mice occur early. 相似文献
90.