Knockout of caspase-like gene, YCA1 , abrogates apoptosis and elevates oxidized proteins in Saccharomyces cerevisiae

Abstract

In our previous study, we established that inhibition of apoptosis by the general caspase inhibitor is associated with an increase in the level of oxidized proteins in a multicellular eukaryotic system. To gain further insight into a potential link between oxidative stress and apoptosis, we carried out studies with Saccharomyces cerevisiae, which contains a gene (YCA1) that encodes synthesis of metacaspase, a homologue of the mammalian caspase, and is known to play a crucial role in the regulation of yeast apoptosis. We show that upon exposure to H 2O2, the accumulation of protein carbonyls is much greater in a ⌬yca1 strain lacking the YCA1 gene than in the wild type and that apoptosis was abrogated in the ⌬yca1 strain, whereas wild type underwent apoptosis as measured by externalization of phosphatidylserine and the display of TUNELpositive nuclei. We also show that H 2O2-mediated stress leads to up-regulation of the 20S proteasome and suppression of ubiquitinylation activities. These findings suggest that deletion of the apoptotic-related caspase-like gene leads to a large H 2O2-dependent accumulation of oxidized proteins and up-regulation of 20S proteasome activity.H2O2 ͉ metacaspase ͉ programmed cell death ͉ proteasome activity ͉ protein carbonyl

Apoptosis in yeast: triggers, pathways, subroutines

“…In a direct competition assay, YCA1-mutant cells are actually outlived by wild-type cells when aged, 10 an observation backed by the finding that YCA1 disruption increases the level of oxidized proteins. 68 Altogether, these data underline the role of YCA1 in particular and metacaspases in general as pivotal players during cell death execution. This, in addition to the common evolutionary origin of caspases, argues for a functional conservation between metacaspases and caspases.…”

Yno1p/Aim14p, a NADPH-oxidase ortholog, controls extramitochondrial reactive oxygen species generation, apoptosis, and actin cable formation in yeast

“…S10B), which was caused by induction of apoptosis and necrosis, as shown below. However, growth was not altered by overexpression of YNO1 in a yca1Δ strain (28,29), indicating that cell death by YNO1 overexpression depends on a functional Yca1p caspase (Fig. S10C).…”

Selenite-induced cell death in Saccharomyces cerevisiae: protective role of glutaredoxins

“…The yeast Yca1p metacaspase mediates apoptosis induced by hydrogen peroxide (Khan et al, 2005;Madeo et al, 2002) or other stimuli (Madeo et al, 2004;Mazzoni & Falcone, 2008). However, agents such as copper provoke apoptosis by a Yca1p-independent mechanism (Liang & Zhou, 2007).…”

“…Oxidative stress is among the apoptosis inducers in yeast (Perrone et al, 2008). Thus, hydrogen peroxide at low concentrations provokes apoptosis in a process dependent on the metacaspase Yca1p and on a functional mitochondrial respiratory chain, while high peroxide concentrations provoke non-apoptotic death (Khan et al, 2005;Madeo et al, 1999Madeo et al, , 2002. Several metals and metalloids also cause apoptosis in yeast cells, which is probably related to their role in ROS formation.…”