Induction of Apoptotic Program in Cell-Free Extracts: Requirement for dATP and Cytochrome c

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

A cell-free system based on cytosols of normally growing cells is established that reproduces aspects of the apoptotic program in vitro. The apoptotic program is initiated by addition of dATP. Fractionation of cytosol yielded a 15 kDa protein that is required for in vitro apoptosis. The absorption spectrum and protein sequence revealed that this protein is cytochrome c. Elimination of cytochrome c from cytosol by immunodepletion, or inclusion of sucrose to stabilize mitochondria during cytosol preparation, diminished the apoptotic activity. Adding back cytochrome c to the cytochrome c-depleted extracts restored their apoptotic activity. Cells undergoing apoptosis in vivo showed increased release of cytochrome c to their cytosol, suggesting that mitochondria may function in apoptosis by releasing cytochrome c.

Related collections

Most cited references 29

Record: found
Abstract: found
Article: not found

Identification and inhibition of the ICE/CED-3 protease necessary for mammalian apoptosis.

D Nicholson, A. Ali, N A Thornberry … (1995)

The protease responsible for the cleavage of poly(ADP-ribose) polymerase and necessary for apoptosis has been purified and characterized. This enzyme, named apopain, is composed of two subunits of relative molecular mass (M(r)) 17K and 12K that are derived from a common proenzyme identified as CPP32. This proenzyme is related to interleukin-1 beta-converting enzyme (ICE) and CED-3, the product of a gene required for programmed cell death in Caenorhabditis elegans. A potent peptide aldehyde inhibitor has been developed and shown to prevent apoptotic events in vitro, suggesting that apopain/CPP32 is important for the initiation of apoptotic cell death.

0 comments Cited 521 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

A novel heterodimeric cysteine protease is required for interleukin-1 beta processing in monocytes.

N A Thornberry, H Bull, J Calaycay … (1992)

Interleukin-1 beta (IL-1 beta)-converting enzyme cleaves the IL-1 beta precursor to mature IL-1 beta, an important mediator of inflammation. The identification of the enzyme as a unique cysteine protease and the design of potent peptide aldehyde inhibitors are described. Purification and cloning of the complementary DNA indicates that IL-1 beta-converting enzyme is composed of two nonidentical subunits that are derived from a single proenzyme, possibly by autoproteolysis. Selective inhibition of the enzyme in human blood monocytes blocks production of mature IL-1 beta, indicating that it is a potential therapeutic target.

0 comments Cited 474 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Bcl-2 functions in an antioxidant pathway to prevent apoptosis.

David M. Hockenbery, Zoltán Oltvai, Xiao-Ming Yin … (1993)

Bcl-2 inhibits most types of apoptotic cell death, implying a common mechanism of lethality. Bcl-2 is localized to intracellular sites of oxygen free radical generation including mitochondria, endoplasmic reticula, and nuclear membranes. Antioxidants that scavenge peroxides, N-acetylcysteine and glutathione peroxidase, countered apoptotic death, while manganese superoxide dismutase did not. Bcl-2 protected cells from H2O2- and menadione-induced oxidative deaths. Bcl-2 did not prevent the cyanide-resistant oxidative burst generated by menadione. Two model systems of apoptosis showed no increment in cyanide-resistant respiration, and generation of endogenous peroxides continued at an inherent rate that was unaltered by Bcl-2. Following an apoptotic signal, cells sustained progressive lipid peroxidation. Overexpression of Bcl-2 functioned to suppress lipid peroxidation completely. We propose a model in which Bcl-2 regulates an antioxidant pathway at sites of free radical generation.