scholarly journals Signal-transduction protein PII from Synechococcus elongatus PCC 7942 senses low adenylate energy charge in vitro

2011 ◽  
Vol 440 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Oleksandra Fokina ◽  
Christina Herrmann ◽  
Karl Forchhammer
Keyword(s):  
Signal Transduction ◽  
Energy Charge ◽  
Inhibitory Effect ◽  
Synechococcus Elongatus ◽  
Adenylate Energy Charge ◽  
Signal Transduction Protein ◽  
Signal Transduction Proteins ◽  
Synechococcus Elongatus Pcc 7942 ◽  
And Control

PII proteins belong to a family of highly conserved signal-transduction proteins that occurs widely in bacteria, archaea and plants. They respond to the central metabolites ATP, ADP and 2-OG (2-oxoglutarate), and control enzymes, transcription factors and transport proteins involved in nitrogen metabolism. In the present study, we examined the effect of ADP on in vitro PII-signalling properties for the cyanobacterium Synechococcus elongatus, a model for oxygenic phototrophic organisms. Different ADP/ATP ratios strongly affected the properties of PII signalling. Increasing ADP antagonized the binding of 2-OG and directly affected the interactions of PII with its target proteins. The resulting PII-signalling properties indicate that, in mixtures of ADP and ATP, PII trimers are occupied by mixtures of adenylate nucleotides. Binding and kinetic activation of NAGK (N-acetyl-L-glutamate kinase), the controlling enzyme of arginine biosynthesis, by PII was weakened by ADP, but relief from arginine inhibition remained unaffected. On the other hand, ADP enhanced the binding of PII to PipX, a co-activator of the transcription factor NtcA and, furthermore, antagonized the inhibitory effect of 2-OG on PII–PipX interaction. These results indicate that S. elongatus PII directly senses the adenylate energy charge, resulting in target-dependent differential modification of the PII-signalling properties.

scholarly journals Staurosporine both activates and inhibits serine/threonine kinases in human platelets

1991 ◽  
Vol 275 (2) ◽  
pp. 301-306 ◽  
Author(s):  
M Kocher ◽  
K J Clemetson
Keyword(s):  
Signal Transduction ◽  
Protein Kinases ◽  
Human Blood ◽  
Blood Platelets ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
And Control ◽  
Human Blood Platelets ◽  
Selection Of

The effects of staurosporine on a selection of protein kinases were investigated with thrombin-stimulated and control human blood platelets. The results demonstrate that staurosporine (1 microM) can lead to activation of certain protein kinases in intact platelets and has a general inhibitory effect on the renaturable protein kinases in vitro. New candidates for protein kinases involved in signal transduction are identified.

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

A STUDY OF THE INHIBITORY EFFECTS OF CHICK WHOLE EYE EXTRACT ON THE DEVELOPMENT OF THE LENS OF THE CHICK EMBRYO IN VITRO

1966 ◽  
Vol 44 (4) ◽  
pp. 661-676 ◽  
Author(s):  
Robert P. Thompson
Keyword(s):  
Chick Embryo ◽  
Nutrient Medium ◽  
Inhibitory Effect ◽  
Reactive System ◽  
Vesicle Formation ◽  
Inhibitory Effects ◽  
Muscle Extract ◽  
Lens Vesicle ◽  
And Control

To demonstrate the phenomenon of homologous inhibition by clearly interpretable results in a readily reactive system, experiments were carried out to study the effect of chick whole eye extract on the development of the vesicular lens of the chick embryo in vitro. The heads of embryos of 11 through 13 somites were explanted onto nutrient medium diluted with varying amounts of the extract, and cultured for 30 hours. A total of 35 embryos exposed to concentrations of 1:1, 1:2, and 1:4 (extract to medium) showed complete inhibition of lens vesicle formation. Of a total of 53 embryos on concentrations of 1:8, 1:16, 1:32, and 1:64, more than 50% showed inhibition of vesicle formation. The inhibitory effect disappeared at a concentration of 1:128. Control material exposed to some equivalent concentrations of nutrient medium – saline mixtures showed inhibition of vesicle formation in only 15% of 33 embryos. Of a total of 27 control embryos exposed to ventricular muscle extract, approximately one-third showed inhibition of vesicle formation at concentrations of 1:8 and 1:16, with the inhibitory effect disappearing at 1:32. The implications of this result are discussed. Other factors and control experiments are described and their value is assessed.

Control of AMP deaminase 1 binding to myosin heavy chain

1998 ◽  
Vol 275 (3) ◽  
pp. C870-C881 ◽  
Author(s):  
Ichiro Hisatome ◽  
Takayuki Morisaki ◽  
Hiroshi Kamma ◽  
Takako Sugama ◽  
Hiroko Morisaki ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Sequence Similarity ◽  
Critical Role ◽  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Amp Deaminase ◽  
Amino Terminal

AMP deaminase (AMPD) plays a central role in preserving the adenylate energy charge in myocytes following exercise and in producing intermediates for the citric acid cycle in muscle. Prior studies have demonstrated that AMPD1 binds to myosin heavy chain (MHC) in vitro; binding to the myofibril varies with the state of muscle contraction in vivo, and binding of AMPD1 to MHC is required for activation of this enzyme in myocytes. The present study has identified three domains in AMPD1 that influence binding of this enzyme to MHC using a cotransfection model that permits assessment of mutations introduced into the AMPD1 peptide. One domain that encompasses residues 178–333 of this 727-amino acid peptide is essential for binding of AMPD1 to MHC. This region of AMPD1 shares sequence similarity with several regions of titin, another MHC binding protein. Two additional domains regulate binding of this peptide to MHC in response to intracellular and extracellular signals. A nucleotide binding site, which is located at residues 660–674, controls binding of AMPD1 to MHC in response to changes in intracellular ATP concentration. Deletion analyses demonstrate that the amino-terminal 65 residues of AMPD1 play a critical role in modulating the sensitivity to ATP-induced inhibition of MHC binding. Alternative splicing of the AMPD1 gene product, which alters the sequence of residues 8–12, produces two AMPD1 isoforms that exhibit different MHC binding properties in the presence of ATP. These findings are discussed in the context of the various roles proposed for AMPD in energy production in the myocyte.

Beauvericin Inhibits the Growth of U251 Glioma Cells and Promotes Apoptosis In Vitro

2020 ◽  
Vol 14 (5) ◽  
pp. 639-644
Author(s):  
Liming Hu ◽  
Tianyi Zhao ◽  
Jia Wang ◽  
Renguang Wang ◽  
Hongshi Bu ◽  
...  
Keyword(s):  
Cyclin D1 ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Glioma Cells ◽  
Inhibitory Effect ◽  
U251 Cell ◽  
Western Blot Assay ◽  
Expression Levels ◽  
Signal Transduction Proteins

To elucidated the inhibitory effect of beauvericin (BEA) on glioma cells and its possible molecular mechanism, in this study, the MTT assay was performed to observed the effect of BEA on cell proliferation, the flow cytometry was used to measure its protective effect on cell apoptosis, and the Western Blot assay was performed to test the expression levels of signal transduction proteins. In the results, the concentration of BEA was 0.5 μmoL/L in the drug group, indicating that it has obvious protect effect to the U251 cells. The apoptosis rates of BEA, Cis and BEA+Cis groups, compared with the U251 group, were 2.93, 3.71 and 5.0 times higher respectively. In addition, the expression levels of Cyclin D1, E, B and Bcl-2 in BEA group were 75, 69, 78 and 67% of that in the U251 group, while Bax and cleaved caspase-3 were twice as much as that in the U251 group. In conclusion, beauvericin can inhibit U251 cell apoptosis and the possible mechanism is to reduce the expression of Cyclin D1, B, E and Bcl-2, while the levels of Bax and cleaved Caspase-3 increased. Thus, BEA has a broad application prospect in the treatment of glioma.

scholarly journals Inhibition of the Formation In Vitro of Putatively Carcinogenic Metabolites Derived from S. haematobium and O. viverrini by Combination of Drugs with Antioxidants

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3842
Author(s):  
Maria João Gouveia ◽  
Verónica Nogueira ◽  
Bruno Araújo ◽  
Fátima Gärtner ◽  
Nuno Vale
Keyword(s):  
Dna Adducts ◽  
Therapeutic Strategy ◽  
Drug Repurposing ◽  
Inhibitory Effect ◽  
Current Treatment ◽  
Combination Drugs ◽  
Therapeutic Alternatives ◽  
And Control ◽  
Novel Therapeutic

Infections caused by Schistosoma haematobium and Opisthorchis viverrini are classified as carcinogenic. Although carcinogenesis might be a multifactorial process, it has been postulated that these helminth produce/excrete oxysterols and estrogen-like metabolites that might act as initiators of their infection-associated carcinogenesis. Current treatment and control of these infections rely on a single drug, praziquantel, that mainly targets the parasites and not the pathologies related to the infection including cancer. Thus, there is a need to search for novel therapeutic alternatives that might include combinations of drugs and drug repurposing. Based on these concepts, we propose a novel therapeutic strategy that combines drugs with molecule antioxidants. We evaluate the efficacy of a novel therapeutic strategy to prevent the formation of putative carcinogenic metabolites precursors and DNA adducts. Firstly, we used a methodology previously established to synthesize metabolites precursors and DNA adducts in the presence of CYP450. Then, we evaluated the inhibition of their formation induced by drugs and antioxidants alone or in combination. Drugs and resveratrol alone did not show a significant inhibitory effect while N-acetylcysteine inhibited the formation of most metabolite precursors and DNA adducts. Moreover, the combinations of classical drugs with antioxidants were more effective rather than compounds alone. This strategy might be a valuable tool to prevent the initiation of helminth infection-associated carcinogenesis.

scholarly journals Labeling of the releasable adenine nucleotides of washed human platelets

Blood ◽  
1977 ◽  
Vol 49 (1) ◽  
pp. 89-99 ◽  
Author(s):  
HJ Reimers ◽  
MA Packham ◽  
JF Mustard
Keyword(s):  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Energy Charge ◽  
Human Platelets ◽  
Transport Processes ◽  
Adenylate Energy Charge ◽  
Prolonged Incubation ◽  
Atp Pool ◽  
Adenine Nucleotide Pool

Abstract In rabbit platelets, the metabolically active ATP pool equilibrates with the releasable ATP pool within 1 day. The studies showing this have now been extended to human platelets. Human platelets labeled with 14C-adenosine or 14C-adenine were incubated for up to 10 hr in vitro at 37 degrees C. After 10 hr, about 12% of the total platelet 14C-ATP and 14C-ADP had become releasable with thrombin (4.2 units/ml). Lysis of platelets did not occur, since less than 1% of the platelet-bound 51Cr from platelets labeled with this radioisotope appeared in the ambient fluid upon thrombin treatment. The 14C-ATP/14C-ADP ratio of the released adenine nucleotides (7.6) was similar to the 14C-ATP/14C-ADP ratio of the nonreleasable adenine nucleotides (7.1) 2 hr after the labeling with 14C-adenosine. However, upon prolonged incubation (10 hr) in vitro, the 14C-ATP/14C-ADP ratio of the releasable adenine nucleotides decreased to 2.7. The adenylate energy charge and the 14C- ATP/14C-ADP ratio of the metabolic adenine nucleotide pool did not change significantly during the time of observation. The 14C-ATP content of the platelets decreased by less than 1% hr of incubation at 37 degrees C. These observations are interpreted to mean that the 14C is transferred from the metabolically active, nonreleasable adenine nucleotide pool of human platelets into the releasable adenine nucleotide pool as ATP and is partially hydrolyzed there to yield ADP. The transfer of ATP across the storage organelle membrane of platelets may be similar to transport processes in the chromaffin cells of the adrenal medulla and may represent a general phenomenon in cells that possess storage organelles containing adenine nucleotides.

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