ADDITIONAL STUDIES ON THE MECHANISM OF ACTION OF ACTH

1965 ◽  
Vol 43 (7) ◽  
pp. 923-932 ◽  
Author(s):  
Kenneth W. McKerns
Keyword(s):  
Pentose Phosphate ◽  
Free System ◽  
Active Complex ◽  
Initial Event ◽  
Rna And Protein Synthesis ◽  
Lysine Residues ◽  
A Cell ◽  
Initial Activation ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Increased Activity

Additional studies are presented to support the concept that ACTH regulates the function of the adrenal cortex by activating adrenal glucose-6-phosphate dehydrogenase. Corticoid synthesis in a cell-free system of adrenal tissue, supplemented with glucose-6-phosphate, can be stimulated by synthetic 23 amino acid ACTH. ACTH is inactive if the lysine residues of the peptide chain are blocked. Estrogen competes with NADP+ binding to glucose-6-phosphate dehydrogenase and inhibits the ACTH stimulus to steroidogenesis. Puromycin and other protein inhibitors have no effect on the initial activation of glucose-6-phosphate dehydrogenase and steroidogenesis. With longer incubation times puromycin can completely inhibit steroidogenesis, possibly by poisoning microsomal or mitochondrial elements. The initial event in the ACTH effect would seem to be the formation of an active complex of ACTH with glucose-6-phosphate dehydrogenase. This increases the rate of metabolism of glucose-6-phosphate and the rate of reduction of NADP+ required for the hydroxylation reactions in corticoid synthesis. The increased activity of the pentose phosphate pathway with increased production of ribose sugars and ATP could increase DNA-directed RNA and protein synthesis as a secondary event.

Mechanism of Action of Divicine in a Cell-free System and in Glucose-6-phosphate Dehydrogenase-deficient Red Cells

1984 ◽  
Vol 12 (4) ◽  
pp. 331-336 ◽  
Author(s):  
Margaret A. Baker ◽  
Amalia Bosia ◽  
Gianpiero Pescarmona ◽  
Franco Turrini ◽  
Paolo Arese
Keyword(s):  
Mechanism Of Action ◽  
Red Cells ◽  
Free System ◽  
Cell Free System ◽  
A Cell ◽  
Glucose 6 Phosphate Dehydrogenase

Modulation of doxorubicin resistance by the glucose-6-phosphate dehydrogenase activity

2011 ◽  
Vol 439 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Manuela Polimeni ◽  
Claudia Voena ◽  
Joanna Kopecka ◽  
Chiara Riganti ◽  
Gianpiero Pescarmona ◽  
...  
Keyword(s):  
Cancer Cell Line ◽  
Human Colon ◽  
Colon Cancer Cell Line ◽  
Pentose Phosphate ◽  
Human Colon Cancer ◽  
Ht29 Cells ◽  
Open Questions ◽  
Associated Proteins ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Increased Activity

How anti-neoplastic agents induce MDR (multidrug resistance) in cancer cells and the role of GSH (glutathione) in the activation of pumps such as the MRPs (MDR-associated proteins) are still open questions. In the present paper we illustrate that a doxorubicin-resistant human colon cancer cell line (HT29-DX), exhibiting decreased doxorubicin accumulation, increased intracellular GSH content, and increased MRP1 and MRP2 expression in comparison with doxorubicin-sensitive HT29 cells, shows increased activity of the PPP (pentose phosphate pathway) and of G6PD (glucose-6-phosphate dehydrogenase). We observed the onset of MDR in HT29 cells overexpressing G6PD which was accompanied by an increase in GSH. The G6PD inhibitors DHEA (dehydroepiandrosterone) and 6-AN (6-aminonicotinamide) reversed the increase of G6PD and GSH and inhibited MDR both in HT29-DX cells and in HT29 cells overexpressing G6PD. In our opinion, these results suggest that the activation of the PPP and an increased activity of G6PD are necessary to some MDR cells to keep the GSH content high, which is in turn necessary to extrude anticancer drugs out of the cell. We think that our data provide a new further mechanism for GSH increase and its effects on MDR acquisition.

scholarly journals Characterization of the terminal stages of chlorophyll (ide) synthesis in etioplast membrane preparations

1975 ◽  
Vol 152 (3) ◽  
pp. 623-655 ◽  
Author(s):  
W T Griffiths
Keyword(s):  
Pentose Phosphate Pathway ◽  
Chlorophyll Biosynthesis ◽  
Pentose Phosphate ◽  
Activation Process ◽  
Active Complex ◽  
Sh Reagents ◽  
Intermittent Illumination ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Etioplast Membranes

1. Chlorophyll (ide) formation from protochlorophyll (ide) that is normally inactive was demonstrated in etioplast membranes isolated from maize and barlley plants, the process being dependent on intermittent illumination and the addition of NADPH. 2. The addition of NADPH to the membranes was shown to result in the conversion of inactive protochlorophyll (ide) absorbing at about 630 nm into a form(s) with light-absorption maxima at about 640 and 652 nm, both of which disappear when chlorophyll (ide) is formed on illumination. 3. The temperature-dependence of the activation process and its response to a variety of reagents were examined. From these, the conclusion is drawn that -SH groups are involved in the activation but in the active complex these are unavailable for reaction with -SH reagents. 4. Evidence is presented for the occurrence of glucose 6-phosphate dehydrogenase activity within etioplasts and the suggestion is made that the oxidative pentose phosphate pathway can provide the NADPH required for chlorophyll biosynthesis during the early stages of greening.

scholarly journals Induction of an inactivation pathway for ecdysteroids in larvae of the cotton leafworm, Spodoptera littoralis

1994 ◽  
Vol 301 (1) ◽  
pp. 89-95 ◽  
Author(s):  
J H Chen ◽  
M Kabbouh ◽  
M J Fisher ◽  
H H Rees
Keyword(s):  
Spodoptera Littoralis ◽  
Actinomycin D ◽  
Hydroxylase Activity ◽  
Free System ◽  
Cotton Leafworm ◽  
Oxygenase Activity ◽  
Rna And Protein Synthesis ◽  
A Cell ◽  
Moulting Hormones ◽  
Aldehyde Derivative

Treatment of the last-instar larvae of the cotton leafworm (Spodoptera littoralis) with ecdysteroids (moulting hormones) results in the induction of an ecdysteroid-inactivation pathway. Administration of ecdysone, 20-hydroxyecdysone or an ecdysteroid agonist, RH 5849, leads to induction of an ecdysteroid 26-hydroxylase activity. This induction occurred in both early sixth-instar larvae and in older larvae which had been head-ligated to prevent the normal developmental increase in ecdysone 20-mono-oxygenase activity. The induction of 26-hydroxylase activity requires both RNA and protein synthesis, as demonstrated by experiments involving actinomycin D and cycloheximide. The 26-aldehyde derivative of ecdysone and ecdyson-26-oic acid were also formed from ecdysone in the RH 5849-induced systems. Formation of the aldehyde and the corresponding 26-oic acid (ecdysonoic acid) from 26-hydroxyecdysone was directly demonstrated in a cell-free system, thus establishing the following inactivation pathway: Ecdysteroid-->26-hydroxyecdysteroid-->ecdysteroid 26-aldehyde-->ecdysteroid 26-oic acid.

scholarly journals Ubiquitin-Independent Degradation of Antiapoptotic MCL-1

2010 ◽  
Vol 30 (12) ◽  
pp. 3099-3110 ◽  
Author(s):  
Daniel P. Stewart ◽  
Brian Koss ◽  
Madhavi Bathina ◽  
Rhonda M. Perciavalle ◽  
Kristen Bisanz ◽  
...  
Keyword(s):  
Myeloid Cell ◽  
Ubiquitin Proteasome System ◽  
Apoptosis Induction ◽  
Wild Type ◽  
Free System ◽  
Cell Lineages ◽  
Lysine Residues ◽  
Ubiquitin Proteasome ◽  
A Cell

ABSTRACT Antiapoptotic myeloid cell leukemia 1 (MCL-1) is an essential modulator of survival during the development and maintenance of a variety of cell lineages. Its turnover, believed to be mediated by the ubiquitin-proteasome system, facilitates apoptosis induction in response to cellular stress. To investigate the contribution of ubiquitinylation in regulating murine MCL-1 turnover, we generated an MCL-1 mutant lacking the lysine residues required for ubiquitinylation (MCL-1KR). Here, we demonstrate that despite failing to be ubiquitinylated, the MCL-1KR protein is eliminated at a rate similar to that of wild-type MCL-1 under basal and stressed conditions. Moreover, the degradation of wild-type MCL-1 is not affected when ubiquitin-activating enzyme E1 activity is blocked. Likewise, both wild-type and MCL-1KR proteins are similarly degraded when expressed in primary lymphocytes. Supporting these findings, unmodified, in vitro-translated MCL-1 can be degraded in a cell-free system by the 20S proteasome. Taken together, these data demonstrate that MCL-1 degradation can occur independently of ubiquitinylation.

The respiratory pathways of tobacco leaves infected with potato virus X

1969 ◽  
Vol 47 (5) ◽  
pp. 731-736 ◽  
Author(s):  
M. M. Dwurazna ◽  
M. Weintraub
Keyword(s):  
Potato Virus ◽  
Potato Virus X ◽  
Pentose Phosphate ◽  
Tobacco Leaves ◽  
Phosphogluconate Dehydrogenase ◽  
Pentose Metabolism ◽  
Healthy Control ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Increased Activity ◽  
Infected Tobacco

In an attempt to define the causes for the increased respiration effected by certain strains of potato virus X (PVX) in tobacco leaves, the oxidative and phosphorylative activities of leaf mitochondrial preparations were studied, as well as the hexose and pentose metabolism of cell-free extracts. No difference was found in mitochondrial activities in preparations from healthy leaves and from leaves infected with the severe ringspot strain at the stage of infection when the respiratory increase was maximal. However, in the cell-free extracts from leaves infected with all four strains of PVX, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase showed substantially increased activity compared to those from healthy control leaves. Phosphoriboisomerase activity was less than that in the healthy controls. Comparison of C6/C1 ratios showed a decrease in both inoculated and systemically infected leaves with all four strains. It is concluded that the previously observed increase in the respiration of PVX-infected tobacco leaves is largely connected with an increase in the activities of the enzymes in the pentose phosphate pathway.

Combination of ribosome and phage display for fast selection of high affinity VHH antibody fragments

2019 ◽  
pp. 27-33
Author(s):  
YuE Kravchenko ◽  
SV Ivanov ◽  
DS Kravchenko ◽  
EI Frolova ◽  
SP Chumakov
Keyword(s):  
Phage Display ◽  
Selection Procedure ◽  
Free System ◽  
Phage Displays ◽  
High Affinity ◽  
Binding Domains ◽  
A Cell ◽  
Vhh Antibodies ◽  
Efficiency Of Selection ◽  
Selection Of

Selection of antibodies using phage display involves the preliminary cloning of the repertoire of sequences encoding antigen-binding domains into phagemid, which is considered the bottleneck of the method, limiting the resulting diversity of libraries and leading to the loss of poorly represented variants before the start of the selection procedure. Selection in cell-free conditions using a ribosomal display is devoid from this drawback, however is highly sensitive to PCR artifacts and the RNase contamination. The aim of the study was to test the efficiency of a combination of both methods, including pre-selection in a cell-free system to enrich the source library, followed by cloning and final selection using phage display. This approach may eliminate the shortcomings of each method and increase the efficiency of selection. For selection, alpaca VHH antibody sequences suitable for building an immune library were used due to the lack of VL domains. Analysis of immune libraries from the genes of the VH3, VHH3 and VH4 families showed that the VHH antibodies share in the VH3 and VH4 gene groups is insignificant, and selection from the combined library is less effective than from the VHH3 family of sequences. We found that the combination of ribosomal and phage displays leads to a higher enrichment of high-affinity fragments and avoids the loss of the original diversity during cloning. The combined method allowed us to obtain a greater number of different high-affinity sequences, and all the tested VHH fragments were able to specifically recognize the target, including the total protein extracts of cell cultures.

scholarly journals Effect of detergents on sterol synthesis in a cell-free system of yeast

1982 ◽  
Vol 23 (6) ◽  
pp. 803-810
Author(s):  
S Hata ◽  
T Nishino ◽  
N Ariga ◽  
H Katsuki
Keyword(s):  
Sterol Synthesis ◽  
Free System ◽  
Cell Free System ◽  
A Cell

scholarly journals Metabolic Anti-Cancer Effects of Melatonin: Clinically Relevant Prospects

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 3018
Author(s):  
Marek Samec ◽  
Alena Liskova ◽  
Lenka Koklesova ◽  
Kevin Zhai ◽  
Elizabeth Varghese ◽  
...  
Keyword(s):  
Cancer Metabolism ◽  
Glucose Transporter ◽  
Aerobic Glycolysis ◽  
Cell Metabolism ◽  
Lactate Production ◽  
Pentose Phosphate ◽  
Metabolic Reprogramming ◽  
Effective Prevention ◽  
Anti Cancer ◽  
Glucose 6 Phosphate Dehydrogenase

Metabolic reprogramming characterized by alterations in nutrient uptake and critical molecular pathways associated with cancer cell metabolism represents a fundamental process of malignant transformation. Melatonin (N-acetyl-5-methoxytryptamine) is a hormone secreted by the pineal gland. Melatonin primarily regulates circadian rhythms but also exerts anti-inflammatory, anti-depressant, antioxidant and anti-tumor activities. Concerning cancer metabolism, melatonin displays significant anticancer effects via the regulation of key components of aerobic glycolysis, gluconeogenesis, the pentose phosphate pathway (PPP) and lipid metabolism. Melatonin treatment affects glucose transporter (GLUT) expression, glucose-6-phosphate dehydrogenase (G6PDH) activity, lactate production and other metabolic contributors. Moreover, melatonin modulates critical players in cancer development, such as HIF-1 and p53. Taken together, melatonin has notable anti-cancer effects at malignancy initiation, progression and metastasing. Further investigations of melatonin impacts relevant for cancer metabolism are expected to create innovative approaches supportive for the effective prevention and targeted therapy of cancers.

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