Regulation of Cell Death Protease Caspase-9 by Phosphorylation
13 Nov 1998-Science (American Association for the Advancement of Science)-Vol. 282, Iss: 5392, pp 1318-1321
TL;DR: In this paper, the kinase Akt and p21-Ras, an Akt activator, induced phosphorylation of pro-caspase-9 (pro-Casp9) in cells.
Abstract: Caspases are intracellular proteases that function as initiators and effectors of apoptosis. The kinase Akt and p21-Ras, an Akt activator, induced phosphorylation of pro-caspase-9 (pro-Casp9) in cells. Cytochrome c-induced proteolytic processing of pro-Casp9 was defective in cytosolic extracts from cells expressing either active Ras or Akt. Akt phosphorylated recombinant Casp9 in vitro on serine-196 and inhibited its protease activity. Mutant pro-Casp9(Ser196Ala) was resistant to Akt-mediated phosphorylation and inhibition in vitro and in cells, resulting in Akt-resistant induction of apoptosis. Thus, caspases can be directly regulated by protein phosphorylation.
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TL;DR: It is demonstrated that Akt also regulates the activity of FKHRL1, a member of the Forkhead family of transcription factors, which triggers apoptosis most likely by inducing the expression of genes that are critical for cell death, such as the Fas ligand gene.
6,481 citations
Cites background from "Regulation of Cell Death Protease C..."
...…member BAD (Datta tion-independent manner by activating the serine/ et al., 1997; del Peso et al., 1997) and the protease threonine kinase Akt, which then phosphorylates and Caspase 9 (Cardone et al., 1998; Y. Gotoh et al., unpubinactivates components of the apoptotic machinery, lished data)....
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TL;DR: Small-molecule therapeutics that block PI3K signalling might deal a severe blow to cancer cells by blocking many aspects of the tumour-cell phenotype.
Abstract: One signal that is overactivated in a wide range of tumour types is the production of a phospholipid, phosphatidylinositol (3,4,5) trisphosphate, by phosphatidylinositol 3-kinase (PI3K) This lipid and the protein kinase that is activated by it — AKT — trigger a cascade of responses, from cell growth and proliferation to survival and motility, that drive tumour progression Small-molecule therapeutics that block PI3K signalling might deal a severe blow to cancer cells by blocking many aspects of the tumour-cell phenotype
5,654 citations
TL;DR: Those Akt substrates that are most likely to contribute to the diverse cellular roles of Akt, which include cell survival, growth, proliferation, angiogenesis, metabolism, and migration are discussed.
5,505 citations
Cites background from "Regulation of Cell Death Protease C..."
...Akt has also been found to directly phosphorylate S196 on human procaspase-9, and this phosphorylation correlates with a decrease in the protease activity of caspase-9 in vitro (Cardone et al., 1998)....
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TL;DR: The mechanisms by which survival factors regulate the PI3K/c-Akt cascade, the evidence that activation of the PI 3K/ c-AKT pathway promotes cell survival, and the current spectrum of c- akt targets and their roles in mediating c- Akt-dependent cell survival are reviewed.
Abstract: The programmed cell death that occurs as part of normal mammalian development was first observed nearly a century ago (Collin 1906). It has since been established that approximately half of all neurons in the neuroaxis and >99.9% of the total number of cells generated during the course of a human lifetime go on to die through a process of apoptosis (for review, see Datta and Greenberg 1998; Vaux and Korsmeyer 1999). The induction of developmental cell death is a highly regulated process and can be suppressed by a variety of extracellular stimuli. The purification in the 1950s of the nerve growth factor (NGF), which promotes the survival of sympathetic neurons, set the stage for the discovery that peptide trophic factors promote the survival of a wide variety of cell types in vitro and in vivo (Levi-Montalcini 1987). The profound biological consequences of growth factor (GF) suppression of apoptosis are exemplified by the critical role of target-derived neurotrophins in the survival of neurons and the maintenance of functional neuronal circuits. (Pettmann and Henderson 1998). Recently, the ability of trophic factors to promote survival have been attributed, at least in part, to the phosphatidylinositide 38-OH kinase (PI3K)/c-Akt kinase cascade. Several targets of the PI3K/c-Akt signaling pathway have been recently identified that may underlie the ability of this regulatory cascade to promote survival. These substrates include two components of the intrinsic cell death machinery, BAD and caspase 9, transcription factors of the forkhead family, and a kinase, IKK, that regulates the NF-kB transcription factor. This article reviews the mechanisms by which survival factors regulate the PI3K/c-Akt cascade, the evidence that activation of the PI3K/c-Akt pathway promotes cell survival, and the current spectrum of c-Akt targets and their roles in mediating c-Akt-dependent cell survival.
4,260 citations
Cites background from "Regulation of Cell Death Protease C..."
...Indeed, immunoprecipitating overexpressed caspase 9 from 32P-labeled cells revealed that Akt phosphorylates caspase 9 at Ser-196 (Cardone et al. 1998)....
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...This idea is supported by the finding that caspases in lysates from cell lines that overexpress constitutively active Ras or Akt are not activated effectively by the GENES & DEVELOPMENT 2913 addition of cytochrome C to the lysates (Cardone et al. 1998)....
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...addition of cytochrome C to the lysates (Cardone et al. 1998)....
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...This phosphorylation event has functional consequences, as extracts from cell lines overexpressing Akt block cytochrome C-mediated caspase 9 activation in vitro (Cardone et al. 1998)....
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...Indeed, immunoprecipitating overexpressed caspase 9 from (32)P-labeled cells revealed that Akt phosphorylates caspase 9 at Ser-196 (Cardone et al. 1998)....
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TL;DR: As the BCL-2 family members reside upstream of irreversible cellular damage and focus much of their efforts at the level of mitochondria, they play a pivotal role in deciding whether a cell will live or die, and it is argued that the amphipathic a-helical BH3 domain serves as a critical death domain in the pro-apoptotic members.
Abstract: A variety of physiological death signals, as well as pathological cellular insults, trigger the genetically programmed pathway of apoptosis (Vaux and Korsmeyer 1999). Apoptosis manifests in two major execution programs downstream of the death signal: the caspase pathway and organelle dysfunction, of which mitochondrial dysfunction is the best characterized (for reviews, see Green and Reed 1998; Thornberry and Lazebnik 1998). As the BCL-2 family members reside upstream of irreversible cellular damage and focus much of their efforts at the level of mitochondria, they play a pivotal role in deciding whether a cell will live or die (Fig. 1). The founder of this family, the BCL-2 proto-oncogene, was discovered at the chromosomal breakpoint of t(14;18) bearing human B-cell lymphomas. The BCL-2 family of proteins has expanded significantly and includes both proas well as anti-apoptotic molecules. Indeed, the ratio between these two subsets helps determine, in part, the susceptibility of cells to a death signal (Oltvai et al. 1993) (Fig. 1). An additional characteristic of the members of this family is their frequent ability to form homoas well as heterodimers, suggesting neutralizing competition between these proteins. A further characteristic of probable functional significance is their ability to become integral membrane proteins. BCL-2 family members possess up to four conserved BCL-2 homology (BH) domains designated BH1, BH2, BH3, and BH4, which correspond to a-helical segments (Adams and Cory 1998; Kelekar and Thompson 1998; Reed 1998) (Fig. 2). Many of the anti-apoptotic members display sequence conservation in all four domains. The pro-apoptotic molecules frequently display less sequence conservation of the first a-helical segment, BH4. Deletion and mutagenesis studies argue that the amphipathic a-helical BH3 domain serves as a critical death domain in the pro-apoptotic members. This concept is supported by an emerging subset of “BH3-domain-only” members who display sequence homology only within the BH3 domain and to date are all pro-apoptotic. However, the three-dimensional structure of at least one BH3-domainonly molecule, BID, demonstrates a very similar overall a-helical content to the anti-apoptotic molecule BCL-XL (Chou et al. 1999; McDonnell et al. 1999). Many BCL-2 family members also contain a carboxy-terminal hydrophobic domain, which in the case of BCL-2 is essential for its targeting to membranes such as the mitochondrial outer membrane (Nguyen et al. 1993).
3,676 citations
Cites background from "Regulation of Cell Death Protease C..."
...In addition to BAD, Akt has been demonstrated to phosphorylate and inactivate caspase-9 (Cardone et al. 1998) and the transcription factor FKHRL1 (Brunet et al. 1999), thereby promoting cell survival....
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References
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