The presence and subcellular localization of caspase 3‐like proteinases in plant cells

Abstract

Caspases play a very important role in initiating and executing apoptotic processes in animal cells. In this study we show that plant mitochondria were able to initiate the activation of caspase 3 in a Xenopus cell free system. Caspase 3-like activity was found to be present in plant cells and could only be inhibited by the specific caspase 3 inhibitor N-acetyl-Asp-GluVal-Asp-fluoromethylketone (Ac-DEVD-fmk) and not by cysteine protease inhibitors. By micro-injection of the caspase 3 substrate in living Chara cells we showed that caspase 3-like activity was mainly present in the cytosol rather than in the vacuole. This is the first time that in vivo caspase 3-like activity has been demonstrated in plants. ß

Toxin release in response to oxidative stress and programmed cell death in the cyanobacterium Microcystis aeruginosa

“…This conclusion is supported by the fact that when cells were preincubated with the caspase inhibitor Ac-DEVD-CHO, caspase activity was essentially eliminated. These findings are in agreement with recent reports demonstrating that caspase activity is a common constituent not only in mammalian systems but in higher plants and lower algae as well (Korthout et al, 2000, Elbaz et al, 2002, Segovia et al, 2003. Our results, in conjunction with the recent caspase-like activity found in Trichodesmium (Berman-Frank et al, 2004), support the notion that PCD has an earlier evolutionary origin and broader significance than previously thought.…”

VEIDase is a principal caspase-like activity involved in plant programmed cell death and essential for embryonic pattern formation

“…23,25,[36][37][38] This is the first study of caspase-like activity in a gymnosperm plant. Neither caspase-1-nor 3-like-activities previously reported for angiosperm cell death systems 8,9,11,13 were found to be involved in spruce embryonic cell death. It is possible that the observed differences in substrate specificity between angiosperm and gymnosperm caspase-like proteases are attributed to a long phylogenetic distance between the two groups of higher plants.…”

“…26 In general, caspase-like activities cannot be inhibited by protease inhibitors other than caspase-specific ones. 8,27 Accordingly, we observed no inhibitory effect of a range of serine and cysteine protease inhibitors (calpain inhibitor I, aprotinin, leupeptin, phenylmethylsulphonyl fluoride (PMSF) and L-1-chloro-3-(4-tosylamido)-7-amino-2-heptanone (TLCK)), or of pepstatin (inhibitor for aspartic acid proteases) or lactacystine (inhibitor for proteasome), on the cleavage of VEID-AMC by cell extracts of Norway spruce (Figure 2a). In contrast, caspase-6 substrate-mimetic inhibitor Ac-VEID-CHO almost completely inhibited this activity at the concentration of 10 mM (Figure 2b).…”

“…Although the implication of plant metacaspases in programmed cell death has not been shown so far, yeast metacaspase YCA1 has been demonstrated as an effective executor for cell death, displaying increased proteolytic activity against caspase-6-specific synthetic substrate VEID-7-amino-4-methylcoumarin (AMC). 7 Second, there is a growing body of physiological and biochemical data suggesting that plant cells contain caspase-1-(i.e., YVADase) and/or 3-like (i.e., DEVDase) proteolytic activities, 8 which correlate with the level of experimentally induced cell death, [9][10][11][12][13] and that the latter can be abolished or delayed by synthetic [9][10][11][12][13] or natural 14,15 caspase-specific inhibitors. As most of these experiments dealt with pathogenor drug-induced cell deaths, they cannot address the roles of caspase-related proteins (metacaspases) and caspase-like proteolytic activity in normal plant development.…”

Transglutaminase activity during senescence and programmed cell death in the corolla of tobacco (Nicotiana tabacum) flowers

“…29 Caspases belong to this enzyme family and are well known to have a relevant role in animal apoptosis, whereas only recently the presence and activity of caspase-like enzymes have been reported in plants, including tobacco leaves, 45 in relation to cell death. 46,47 A relationship exists between caspases and TGase during animal PCD: the latter enzyme is one of the substrates of caspases during lymphoid cell apoptosis. 48 Moreover, caspases cleave several proteins which also undergo tTGase-catalysed post-translational modifications during apoptosis.…”