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961.
Kowalski W Nocon D Gamian A Kołodziej J Rakus D 《Journal of cellular physiology》2012,227(6):2613-2621
Cancer cells prefer anaerobic ATP synthesis, regardless of the availability of oxygen. It has been hypothesized that in these cells, glycolytic enzymes associate into a large complex, which results in an increased efficiency of glycolytic flux. However, there is no convincing in vivo evidence supporting this hypothesis. Here, we show that all the enzymes of triose phosphate metabolism, from aldolase to pyruvate kinase consecutively, form a macromolecular complex in vivo and that disruption of such complex significantly inhibits lactate release and ATP synthesis in the glycolytic pathway. Composition of the complex and the effectiveness of the glycolytic flux depends on lactate and glucose concentration. High concentrations of exogenous lactate reduces association of the C-terminal region phosphoglycerate mutase (PGAM) with the complex which results in its disruption and inhibition of ATP synthesis. Additionally, high lactate affects nuclear localization of PGAM and ceases cell proliferation. Our findings might provide new prospects for cancer treatment using low-molecular weight competitors to destabilize the glycolytic complex and reduce proliferative potential of cancer cells. 相似文献
962.
Bernard M. A. G. Piette Junli Liu Kasper Peeters Andrei Smertenko Timothy Hawkins Michael Deeks Roy Quinlan Wojciech J. Zakrzewski Patrick J. Hussey 《PloS one》2009,4(8)
Microtubules are self-assembling polymers whose dynamics are essential for the
normal function of cellular processes including chromosome separation and
cytokinesis. Therefore understanding what factors effect microtubule growth is
fundamental to our understanding of the control of microtubule based processes.
An important factor that determines the status of a microtubule, whether it is
growing or shrinking, is the length of the GTP tubulin microtubule cap. Here, we
derive a Monte Carlo model of the assembly and disassembly of microtubules. We
use thermodynamic laws to reduce the number of parameters of our model and, in
particular, we take into account the contribution of water to the entropy of the
system. We fit all parameters of the model from published experimental data
using the GTP tubulin dimer attachment rate and the lateral and longitudinal
binding energies of GTP and GDP tubulin dimers at both ends. Also we calculate
and incorporate the GTP hydrolysis rate. We have applied our model and can mimic
published experimental data, which formerly suggested a single layer GTP tubulin
dimer microtubule cap, to show that these data demonstrate that the GTP cap can
fluctuate and can be several microns long. 相似文献
963.
Katarzyna Kozieł Magdalena Lebiedzinska Gyorgy Szabadkai Marta Onopiuk Wojciech Brutkowski Katarzyna Wierzbicka Grzegorz Wilczyński Paolo Pinton Jerzy Duszyński Krzysztof Zabłocki Mariusz R. Wieckowski 《The international journal of biochemistry & cell biology》2009,41(12):2440-2449
A proper cooperation between the plasma membrane, the endoplasmic reticulum and the mitochondria seems to be essential for numerous cellular processes involved in Ca2+ signalling and maintenance of Ca2+ homeostasis. A presence of microsomal and mitochondrial proteins together with those characteristic for the plasma membrane in the fraction of the plasma membrane associated membranes (PAM) indicates a formation of stabile interactions between these three structures. We isolated the plasma membrane associated membranes from Jurkat cells and found its significant enrichment in the plasma membrane markers including plasma membrane Ca2+-ATPase, Na+, K+-ATPase and CD3 as well as sarco/endoplasmic reticulum Ca2+ ATPase as a marker of the endoplasmic reticulum membranes. In addition, two proteins involved in the store-operated Ca2+ entry, Orai1 located in the plasma membrane and an endoplasmic reticulum protein STIM1 were found in this fraction. Furthermore, we observed a rearrangement of STIM1-containing protein complexes isolated from Jurkat cells undergoing stimulation by thapsigargin. We suggest that the inter-membrane compartment composed of the plasma membrane and the endoplasmic reticulum, and isolated as a stabile plasma membrane associated membranes fraction, might be involved in the store-operated Ca2+ entry, and their formation and rebuilding have an important regulatory role in cellular Ca2+ homeostasis. 相似文献
964.
Background
Acute lymphoblastic leukemia (ALL) is a common form of cancer in children. Currently, bone marrow biopsy is used for diagnosis. Noninvasive biomarkers for the early diagnosis of pediatric ALL are urgently needed. The aim of this study was to discover potential protein biomarkers for pediatric ALL.Methods
Ninety-four pediatric ALL patients and 84 controls were randomly divided into a "training" set (45 ALL patients, 34 healthy controls) and a test set (49 ALL patients, 30 healthy controls and 30 pediatric acute myeloid leukemia (AML) patients). Serum proteomic profiles were measured using surface-enhanced laser desorption/ionization-time-of-flight mass spectroscopy (SELDI-TOF-MS). A classification model was established by Biomarker Pattern Software (BPS). Candidate protein biomarkers were purified by HPLC, identified by LC-MS/MS and validated using ProteinChip immunoassays.Results
A total of 7 protein peaks (9290 m/z, 7769 m/z, 15110 m/z, 7564 m/z, 4469 m/z, 8937 m/z, 8137 m/z) were found with differential expression levels in the sera of pediatric ALL patients and controls using SELDI-TOF-MS and then analyzed by BPS to construct a classification model in the "training" set. The sensitivity and specificity of the model were found to be 91.8%, and 90.0%, respectively, in the test set. Two candidate protein peaks (7769 and 9290 m/z) were found to be down-regulated in ALL patients, where these were identified as platelet factor 4 (PF4) and pro-platelet basic protein precursor (PBP). Two other candidate protein peaks (8137 and 8937 m/z) were found up-regulated in the sera of ALL patients, and these were identified as fragments of the complement component 3a (C3a).Conclusion
Platelet factor (PF4), connective tissue activating peptide III (CTAP-III) and two fragments of C3a may be potential protein biomarkers of pediatric ALL and used to distinguish pediatric ALL patients from healthy controls and pediatric AML patients. Further studies with additional populations or using pre-diagnostic sera are needed to confirm the importance of these findings as diagnostic markers of pediatric ALL. 相似文献965.
966.
967.
Wojciech?BurzaEmail author Ewa?Dziadczyk Adam?Tylicki Mieczys?aw?Kura? Stefan?Malepszy 《Acta Physiologiae Plantarum》2003,25(4):385-394
A liquid meristematic root primordia culture (RPC) of Solanum lycopersicoides Dun. based on persistent rhizogenesis in a modified Murashige and Skoog (1962) medium supplemented with NAA (15 mg·l−1) or 2,4-D (1 mg·l−1) was described. The meristematic clumps (2–3 mm in diameter) originating from NAA supplemented medium were capable of regenerating
plants through the callus stage (up to 70 %). Efficient direct plant regeneration (up to 21 %) was possible from numerous
single globular-shaped root primordia (RP) structures liberated from the parental aggregates in 2,4-D supplemented proliferation
medium without NH4NO3 and with a 2.5 fold increase in KNO3. The RP converted into plantlets (artificial seedlings) on solid or liquid media without growth growth regulators through
the unipolar followed by the mace-shaped bipolar structure stages. The use of apical shoot bud, root apices or root segments
as a primary explants brought about RPC induction and plant regeneration. The plants derived from 2 years old culture were
phenotypically identical to their parental S. lycopersicoides plants and possessed the same ploidy. 相似文献
968.
Transformation efficiencies as high as 107 transformants g–1 DNA have been previously reported for pseudomonads using electroporation protocols established for E. coli with plasmid DNAs prepared from methylation proficient E. coli hosts. We report here a protocol for electroporation of plasmid DNAs into a biocontrol strain of Pseudomonas syringae which could not be electroporated by standard E. coli methods. Transformation efficiencies of 107 or higher were obtained with DNA recovered from initial P. syringae transformation or with DNA prepared from methylation deficient E. coli. Both plasmids used in this study were stably maintained in the absence of selection for at least 50 generations. 相似文献
969.
970.
Dynamic NMR structures of [Rp]- and [Sp]-phosphorothioated DNA-RNA hybrids: is flexibility required for RNase H recognition?
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Tonelli M Ulyanov NB Billeci TM Karwowski B Guga P Stec WJ James TL 《Biophysical journal》2003,85(4):2525-2538
Chemically modified DNA oligonucleotides have been crucial to the development of antisense therapeutics. High-resolution structural studies of pharmaceutically relevant derivatives have been limited to only a few molecules. We have used NMR to elucidate the structure in solution of two DNA-RNA hybrids with the sequence d(CCTATAATCC).r(GGAUUAUAGG). The two hybrids contain an unmodified RNA target strand, whereas the DNA strand contains one of two different stereoregular sugar-phosphate backbone linkages at each nucleotide: 1), [Rp]-phosphorothioate or 2), [Sp]-phosphorothioate. Homonuclear two-dimensional spectroscopy afforded nearly complete nonlabile proton assignments. Distance bounds, calculated from the nuclear Overhauser effect (NOE) crosspeak intensities via a complete relaxation matrix approach with the program MARDIGRAS, were used to restrain the structure of the two hybrids during simulations of molecular dynamics. Analysis of restrained molecular dynamics trajectories suggests that both hybrids are flexible, requiring the use of molecular dynamics with time-averaged restraints (MDtar) to generate ensembles of structures capable of satisfying the NMR data. In particular, the deoxyribose sugars of the DNA strand show strong evidence of repuckering. Furthermore, deoxyribose sugar repuckering is accompanied by increased flexibility of overall helical geometry. These observations, together with the analysis of the crystal structure of a hybrid duplex in complex with ribonuclease H (RNase H), suggested that this flexibility may be required for recognition by RNase H. 相似文献