Bax, Bak and Bid: Key Mediators of Apoptosis

Dempsey, Clare; Roberts, D. F.; Dive, Caroline

doi:10.1002/9783527619665.ch12

Cited by 3 publications

(4 citation statements)

References 204 publications

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“…Similar observations were made by Dempsey [14] on the biological isomerization of cholesta-7,24-dien-3p-01 to cholesta-8,24-dien-30-01. However the reversibility of this reaction has been recently studied by Wilton et al [5] with a different experimental approach ; cholest-7-en-30-01 was incubated with both 10000 x g supernatant and 105000 x g microsomes of rat liver under anaerobic conditions in tritiated water.…”

Section: Discussionsupporting

confidence: 86%

The Reversibility of the Isomerization of the Δ⁸ to Δ⁷ Bond in Cholesterol Biosynthesis

Scala

Galli-Kienle

Anastasia

et al. 1974

European Journal of Biochemistry

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The reversibility of the isomerization of the A s to A7 bond in the biosynthesis of cholesterol has been re-examined. For this purpose [4-'4C,9a-3H,]cholest-7-en-3~-ol has been incubated with the 10000 x g soluble fraction of rat liver homogenate both under anaerobic and aerobic conditions. Almost complete exchange of the 9a hydrogen with the medium has been observed under anaerobic conditions, whereas under aerobic conditions 34 % exchange with the medium has been calculated from the 3H/14C ratio found in cholesterol isolated after incubation. The stereospecificity of the A7 to As isomerization has been established by incubating in analogous conditions [4-14C,7-3Hl]cholest-7-en-3P-01. The synthesis of each labelled substrate is described.Cholesterol biosynthesis involves the isomerization of the double bond at position 8 of lanosterol to the 7 position. The reaction may occur at any step of the biosynthesis after the removal of the methyl group at C-32 [l]. The isomerization implies the stereospecific removal of the 7P hydrogen and the addition of a solvent hydrogen at the 9a positionThe possible reversibility of this reaction has been considered and different authors [l ,4] have presented evidence that no detectable amounts of cholest-8-en-3P-01 are formed by incubating cholest-7-en-3~-01 with a microsomal preparation of rat liver. On the other hand it has been recently demonstrated that tritium from the medium is incorporated at the 9a position of cholest-7-en-3/3-01, when this sterol is incubated either with microsomes or with the 10000 x g soluble fraction of rat liver homogenate under anaerobic conditions [5]. On the basis of these results it has been concluded that the biological conversion of cholest-8-en-3P-01 to cholest-7-en-38-01 is a reversible process. However under physiological conditions cholest-7-en-3/l-ol is efficiently converted to cholesterol and it does not accumulate in the same way as under the anaerobic conditions utilized in the above-mentioned experiments. It was of interest therefore to consider the reversibility of the isomerization under aerobic conditions. For this purpose [4-14C,9a-3H1]cholest-7-en3p-01 was synthesized and incubated with the 10 000 x g soluble fraction of rat liver homogenate under aerobic ~3 1 .conditions. The decreased 3H/14C ratio found in cholesterol derived from the incubations demonstrated that isomerization from cholest-7-en-3P-01 to cholest-8-en-3P-01 takes place also during the biological conversion of the former to cholesterol. The stereospecificity of the reaction is also demonstrated under both aerobic an anaerobic conditions. MATERIALS AND METHODS MaterialsTritiated water and tritiated sodium boron hydride were obtained from Amersham (U.K.) ; N,O-bis(trimethylsily1)-trifluoroacetamide from Pierce Chemicals; osmium tetroxide from Merck ; cholesta-5,7-dien-38-01 acetate from Fluka A.G. Radioactive Thin-Layer Chromatography ScanningThis was carried out using a Packard radioactivechromatogram scanning system, model 7201 and silica gel H F layers (0.25 mm ...

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Section: Discussionsupporting

confidence: 86%

The Reversibility of the Isomerization of the Δ⁸ to Δ⁷ Bond in Cholesterol Biosynthesis

Scala

Galli-Kienle

Anastasia

et al. 1974

European Journal of Biochemistry

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“…This could be taken as an indication that the iteron-binding recognition domain of the Rep proteins Is located at their C-moiety. In the staphylococcal plasmid pT181, a C-terminal region of the initiator RepC protein is involved in its DNA-binding specificity (Novick, 1989: Dempsey et al,. 1992 Fig.4.…”

Section: The Rep Proteinsmentioning

confidence: 99%

“…Several ways can be envisaged for this exchange of genetic information, conjugal mobilization and transformation being the most likely. Various broad-host-range ptasmids can be transferred to and stably inherited in a wide variety of bacterial hosts (Gormley and Davies, 1991). Among promiscuous plasmids, a whole group of small multicopy replicons.…”

Section: Introductionmentioning

confidence: 99%

Rolling circle‐replicating plasmids from Gram‐positive and Gram‐negative bacteria: a wall falls

Solar

Moscoso

Espinosa

1993

Molecular Microbiology

172

122

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Rolling circle-replicating plasmids constitute a group of small, promiscuous multicopy replicons spread among eubacteria. Until recently, rolling circle replication seemed to be limited to small plasmids from Gram-positive hosts and to single-stranded bacteriophages from Gram-negative bacteria. However, characterization of two small plasmids from Gram-negative hosts has shown that this replication mechanism is general among eubacteria. This review focuses on a family of highly related promiscuous plasmids that replicate by the rolling circle mechanism, and that have been isolated from various Gram-positive bacteria and from the Gram-negative bacterium Helicobacter. They all share homologies at the leading-strand origins and at the initiator of replication proteins. The plasmids of this family have directly repeated sequences at their plus origin of replication, which is located 5' from the start point of the mRNA for the initiation of replication protein. Replication is controlled by an antisense RNA and by a transcriptional repressor protein. The features and regulatory circuits of replication of this plasmid family seem to be unique among rolling circle-replicating plasmids. Members of this family replicate autonomously in Gram-positive and -negative hosts.

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“…7,8 In addition, evidence has been presented that Bcl-2 over expression resulted in the resistance of cells to doxorubicin (DOX) and paclitaxel. 9,10 It is clear that multiple factors are involved in conferring multidrug resistance and that, regardless of the mechanism, strategies to overcome the phenotype are vital.…”

Section: Introductionmentioning

confidence: 99%

<p>Psoralen-loaded lipid-polymer hybrid nanoparticles enhance doxorubicin efficacy in multidrug-resistant HepG2 cells</p>

Yao¹,

Cai²,

Callaghan³

et al. 2019

IJN

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Background: Psoralen (PSO), a major active component of Psoralea corylifolia, has been shown to overcome multidrug resistance in cancer. A drug carrier comprising a lipid-monolayer shell and a biodegradable polymer core for sustained delivery and improved efficacy of drug have exhibited great potential in efficient treatment of cancers. Methods: The PSO-loaded lipid polymer hybrid nanoparticles were prepared and characterized. In vitro cytotoxicity assay, cellular uptake, cell cycle analysis, detection of ROS level and mitochondrial membrane potential (ΔΨm) and western blot were performed. Results: The P-LPNs enhanced the cytotoxicity of doxorubicin (DOX) 17-fold compared to free DOX in multidrug resistant HepG2/ADR cells. Moreover, P-LPNs displayed pro-apoptotic activity, increased levels of ROS and depolarization of ΔΨm. In addition, there were no significant effects on cellular uptake of DOX, cell cycle arrest, or the expression of P-glycoprotein. Mechanistic studies suggested that P-LPNs enhanced DOX cytotoxicity by increased release of cytochrome c and enhanced caspase3 cleavage, causing apoptosis in HepG2/ADR cells. Conclusion: The lipid-polymer hybrid nanoparticles can be considered a powerful and promising drug delivery system for effective cancer chemotherapy.

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Bax, Bak and Bid: Key Mediators of Apoptosis

Cited by 3 publications

References 204 publications

The Reversibility of the Isomerization of the Δ⁸ to Δ⁷ Bond in Cholesterol Biosynthesis

The Reversibility of the Isomerization of the Δ⁸ to Δ⁷ Bond in Cholesterol Biosynthesis

Rolling circle‐replicating plasmids from Gram‐positive and Gram‐negative bacteria: a wall falls

<p>Psoralen-loaded lipid-polymer hybrid nanoparticles enhance doxorubicin efficacy in multidrug-resistant HepG2 cells</p>

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Bax, Bak and Bid: Key Mediators of Apoptosis

Cited by 3 publications

References 204 publications

The Reversibility of the Isomerization of the Δ8 to Δ7 Bond in Cholesterol Biosynthesis

The Reversibility of the Isomerization of the Δ8 to Δ7 Bond in Cholesterol Biosynthesis

Rolling circle‐replicating plasmids from Gram‐positive and Gram‐negative bacteria: a wall falls

<p>Psoralen-loaded lipid-polymer hybrid nanoparticles enhance doxorubicin efficacy in multidrug-resistant HepG2 cells</p>

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The Reversibility of the Isomerization of the Δ⁸ to Δ⁷ Bond in Cholesterol Biosynthesis

The Reversibility of the Isomerization of the Δ⁸ to Δ⁷ Bond in Cholesterol Biosynthesis