A Unified Model for Apical Caspase Activation

Boatright, Kelly M.; Renatus, Martin; Scott, Fiona L.; Sperandio, Sabina; Shin, Hwain; Pedersen, Irene M.; Ricci, Jean-Ehrland; Edris, Wade; Sutherlin, Daniel P.; Green, Douglas R.; Salvesen, Guy S.

doi:10.1016/s1097-2765(03)00051-0

Cited by 855 publications

(741 citation statements)

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“…[48][49][50] These recruitment platforms integrate cellular signals, promote dimerization of initiator caspases and lead to the formation of an active enzyme proficient to initiate specific signaling cascades. 51,52 These platforms are multiprotein complexes consisting of various molecules assembled on a central scaffold protein that characteristically possesses three main domains: a region involved in ligand sensing, a domain driving oligomerization and a domain involved in recruiting the caspases. The prototypical example is the apoptosome scaffold protein Apaf-1.…”

Section: Activation Of Inflammatory Caspases: Inflammasomes and Othermentioning

confidence: 99%

Inflammatory caspases and inflammasomes: master switches of inflammation

2006

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Fifteen years have passed since the cloning and characterization of the interleukin-1b-converting enzyme (ICE/caspase-1), the first identified member of a family of proteases currently known as caspases. Caspase-1 is the prototypical member of a subclass of caspases involved in cytokine maturation termed inflammatory caspases that also include caspase-4 caspase -5, caspase -11 and caspase -12. Efforts to elucidate the molecular mechanisms involved in the activation of these proteases have uncovered an important role for the NLR family members, NALPs, NAIP and IPAF. These proteins promote the assembly of multiprotein complexes termed inflammasomes, which are required for activation of inflammatory caspases. This article will review some evolutionary aspects, biochemical evidences and genetic studies, underlining the role of inflammasomes and inflammatory caspases in innate immunity against pathogens, autoinflammatory syndromes and in the biology of reproduction. Inflammatory CaspasesThe history of caspases began with the identification of an aspartate-specific protease activity involved in the conversion of the 31 kDa proIL-1b precursor to its active 17 kDa biologically active form, 1,2 and the identification of caspase-1 as the protease responsible for proIL-1b maturation. 3,4 The subsequent discovery of ced-3, that shares similarities with caspase-1 and which is involved in programmed cell death (PCD) in Caenorhabditis elegans, suggested that caspases might play fundamental roles in apoptosis. 5 As reviewed in the papers accompanying this issue of Cell Death and Differentiation, the role of apoptotic caspases in C. elegans and in vertebrates is crucial and deal with many facets of cell biology, development and diseases. In this review, we will focus on a subset of caspases present only in vertebrates and known as inflammatory caspases.Inflammatory caspases (also known as group I caspases) are encoded by three main genes in humans caspase-1, caspase-4 and caspase-5 and three main genes in mouse, caspase-1, caspase-11 and caspase-12. 6,7 In mammals, these caspases are characterized by the presence of a CARD domain at the N-terminus (Figure 1a). Human, chimp and mouse inflammatory caspases share significant similarity and are organized in a single locus (Figure 1c). Phylogenetic analysis of the conserved CARD domain suggests that the inflammatory caspases can be separated in evolutionaryrelated clusters (Figure 1b). The caspase-1 cluster contains caspase-1 and four other genes encoding decoy caspases: cop, inca1, inca2 and iceberg. These decoy caspase-1-like genes are absent in the mouse genome, suggesting that they have arisen recently by duplication of caspase-1. Although human and mouse caspase-1 are likely orthologues, sequence analysis suggests that human caspase-4 and caspase-5 have originated from a duplication of caspase-11. 7 However, the human caspase-12 gene, which in the chimp genome contains an SHG box important for it enzymatic activity, 8 evolved towards an enzymatically inactive form at some stage...

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Section: Activation Of Inflammatory Caspases: Inflammasomes and Othermentioning

confidence: 99%

Inflammatory caspases and inflammasomes: master switches of inflammation

2006

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“…Upon ligand binding, death receptors recruit an adapter protein called FADD (56)(57)(58), which brings caspase-8 to the DISC where it is dimerized and catalytically activated (59). Active caspase-8 can then directly activate effector caspases such as caspase-3 or can activate the intrinsic apoptosis pathway by cleaving the BH3-only protein Bid resulting in its translocation to the mitochondria (60).…”

Section: Regulation Of Apoptosismentioning

confidence: 99%

Apoptosis and autophagy: regulatory connections between two supposedly different processes

2007

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Apoptosis and autophagy are genetically-regulated, evolutionarily-conserved processes that regulate cell fate. Both apoptosis and autophagy are important in development and normal physiology and in a wide range of diseases. Recent studies show that despite the marked differences between these two processes, their regulation is intimately connected and the same regulators can sometimes control both apoptosis and autophagy. In this review, I discuss some of these findings, which provide possible molecular mechanisms for crosstalk between apoptosis and autophagy and suggest that it may be useful to think of these processes as different facets of the same cell death continuum rather than completely separate processes. KeywordsAutophagy; Apoptosis; Bcl-2, FADD; Atg 5In the early to mid 1990s there was a rapid increase in our understating about the regulation of apoptosis. Fifteen or so years later we are in the midst of a similarly exciting period for understanding autophagy with very rapid growth of publications on the regulation and function of this process (1). Autophagy (the form of autophagy discussed here is macroautophagy, other forms-microautophagy and chaperone-mediated autophagy share the same lysosomal degradation mechanism but differ in the way that material is delivered to the lysosome) is a degradative process involving sequestration of parts of the cytoplasm in double membrane vesicles (autophagic vesicles or autophagosomes) that fuse with lysosomes forming the autophagolysosome. In the autophagolysosome, the cytoplasmic material that was engulfed is hydrolyzed and the resulting amino acids and other macromolecular precursors can be recycled (2-4), see Fig 1 for a schematic of the process. Autophagy is a mechanism by which organelles are removed and is the primary degradation mechanism for long-lived proteins and thus maintains quality control for proteins and organelles. Autophagy is ubiquitous in eukaryotic cells and important in development and in diverse pathophysiological conditions (5)-for example providing protection against neurodegeneration (6,7), infections (8,9) and tumor development (10-13). Cells that are deficient in autophagy also demonstrate enhanced chromosomal instability (14,15), which may be related to the tumorigenesis associated with autophagy deficiency.Autophagy is important in cell death decisions and can protect cells by preventing them from undergoing apoptosis. For example, increased autophagy in nutrient deprived or growth factorwithdrawn cells allows cell survival (16,17) by inhibiting apoptosis. Autophagy also protects cells from various other apoptotic stimuli (18). It is not clear how autophagy stops cells from undergoing apoptosis; one suggested mechanism is the sequestration of damaged mitochondria (18) thus preventing released cytochrome c from being able to form a functional apoptosome NIH Public Access Autophagic cell death (also known as Type II programmed cell death to distinguish it from apoptosis or Type I programmed cell death) (20-22) has been describ...

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“…The most commonly used tools include caspase-specific anti-sera as well as fluorogenic substrates and inhibitors. Unfortunately, antibody reagents often do not provide an accurate measure of caspase activity since several caspase family members (caspases 8/10 and 9) do not require proteolytic processing for activation [2,3]. Furthermore, recent evidence suggests that caspase-7 (an executioner caspase) activation occurs via a catalytically active full-length intermediate that cannot be differentiated from the non-cleaved inactive zymogen using antibodies [4,5].…”

Section: Dear Editormentioning

confidence: 99%

“…To test inhibitor selectivity against caspases 3, 7, and 9 we used an apoptotic proteome in which the intrinsic apoptotic pathway is activated through addition of cytochrome c and dATP [9]. Since there is currently no simple method to monitor endogenous caspase-8 activity, we tested the inhibitors against purified recombinant caspase-8 at the physiologically relevant concentration of 50 nM (See Supplement 1 for Materials and Methods) [2].…”

Section: Dear Editormentioning

confidence: 99%