The translational inhibitor cycloheximide represses growth factor depletion-induced apoptosis in an alb-SV40T transgenic rat liver cell line

Abstract

A transgenic rat line carrying the alb-SV40A of apoptosis. Described as a counterpart of mitosis, transgene has been described by this laboratory. Several apoptosis has been the focus of a large number of studcell lines have been established from the livers of two of ies since it was first described by Kerr et al. [1][2][3][4][5][6] Affecting these rats. One of these cell lines, L37, exhibits a large single or small groups of cells, apoptosis exhibits nuclear/cytoplasmic ratio and a well-differentiated cyto-changes in cellular ultrastructure that are distinct plasm containing numerous organelles. When L37 cells from the process of necrosis. 7,8 One of the first ultraare placed into culture medium lacking necessary structural changes observed in the apoptotic process is growth factors, cellular proliferation continues for 48 the shrinkage and detachment of apoptotic cells from with the dilation and vesiculation of the endoplasmic cent cells, eventually sloughing off the culture plate surface, with most cell deaths occurring between 48 and 96 reticulum 9 ; this forces intracellular fluids and ions out hours after medium change. Microscopic examination of of the cytoplasm. 10 Endoplasmic reticulum vesicles fuse sloughing cells indicates they possess highly convoluted with the plasma membrane, resulting in a highly conand blebbed plasma membranes, a morphological char-voluted and blebbed plasma membrane. 11 In addition, acteristic of apoptosis. Ultrastructural studies demon-there is a loss of plasma membrane functions, including strate the ubiquitous presence of apoptotic bodies. When loss of cell junctions and surface microvilli. Concurrent DNA isolated from growth factor-depleted cells is re-with the changes occurring in the endoplasmic reticusolved on agarose gels, DNA fragmentation ladders are lum, cytoplasm, and plasma membrane, nuclear events observed at times of maximum apoptotic change. Quanlead to the condensation and margination of the chrotitative analysis of L37 cells between 48 and 96 hours matin. In contrast to these subcellular changes, other after the removal of the culture medium shows that 59% { 2% of the cells undergo apoptosis. When cyclohexi-organelles remain relatively intact. In a very rapid promide, puromycin, or actinomycin D is added to the L37 cess lasting only minutes, the apoptotic cell fragments cultures, only cycloheximide is able to repress apoptosis, into membrane-encapsulated, smooth-surfaced apoindicating that the mechanism of apoptosis in the L37 ptotic bodies. The number and size of apoptotic bodies liver-derived cell line requires a cycloheximide-sensitive produced by a single ruptured cell vary. The apoptotic translational event. The extremely high rate of bodies may contain condensed nuclear or cytoplasmic apoptosis, together with the maintenance of hepatocel-material, including intact organelles. In vivo, the apo- 1601.)In our laboratory, we have developed a line of transgenic rats 13 in which the transgene is the mouse The loss of cell number homeostasis can occur either al...

Eukaryotic Translation Initiation Factor 4G Is Targeted for Proteolytic Cleavage by Caspase 3 during Inhibition of Translation in Apoptotic Cells

“…There has been a debate about whether ongoing translation is required for apoptosis induction to occur, with evidence from some experimental systems suggesting that apoptosis does not require de novo protein synthesis (29,33,36,38). Conversely, other reports have shown that de novo protein synthesis is required for the cells to become apoptotic in response to nutrient deprivation or steroids (8,9,34). Even though this conflict likely reflects differences in the multiple pathways which can trigger apoptosis, our results do not contribute to this debate, since translation was not inhibited for more than 8 h after induction of apoptosis began.…”

“…Since the components of the execution machinery of apoptosis, i.e., the caspases, are already present in the cell at induction, de novo protein synthesis is not required for induction of apoptosis in most systems (29,33,36,38). On the other hand, it has been reported that in some cases, protein synthesis was necessary to induce apoptosis when nutrient deprivation or sterols were used to induce apoptosis (8,9,34). In these systems, expression of certain factors was necessary for induction of apoptosis, and apoptosis could be repressed by addition of translation inhibitors such as cycloheximide (8).…”

“…On the other hand, it has been reported that in some cases, protein synthesis was necessary to induce apoptosis when nutrient deprivation or sterols were used to induce apoptosis (8,9,34). In these systems, expression of certain factors was necessary for induction of apoptosis, and apoptosis could be repressed by addition of translation inhibitors such as cycloheximide (8). However, even less is known about translation control events during the execution phase of apoptosis, other than the observation in several systems that protein synthesis is eventually inhibited in apoptotic cells (35).…”

Regulation of translation initiation following stress

“…For example, p53-induced apoptosis has been shown to require new protein synthesis in order for the full program to be completed (Polyak et al, 1997). Similarly, nutrient deprivation (Bulera et al, 1996;Schulz et al, 1996), ionizing radiation (our unpublished results), and nonsteroidal anti-in¯ammatory drugs (NSAIDs) (Chan et al, 1998)-induced apoptosis can be inhibited by cycloheximide suggesting that ongoing protein synthesis is needed.…”

An organometallic analogue of combretastatin A-4 and its apoptosis-inducing effects on lymphoma, leukemia and other tumor cells in vitro

“…36 The observed dependence of NAHO27-induced apoptosis on overexpression of Bcl-2 (an anti-apoptotic protein of the intrinsic pathway) and on overexpression of smac/DIABLO (a pro-apoptotic mitochondrial protein) 37 further confirmed that NAHO27-induced apoptosis follows the intrinsic pathway – in line with the observation that apoptosis induction is slightly suppressed in the presence of NAC as a ROS-suppressing agent. Using cycloheximide (an inhibitor of transcriptional-steered apoptosis) 38–40 we could show that NAHO27-induced apoptosis is influenced by transcriptional or translational changes. And by means of gene expression analysis, we detected a 9-fold up-regulation of the pro-apoptotic harakiri gene in lymphoma cells treated with NAHO27.…”