Identification of an upstream regulatory pathway controlling actin-mediated apoptosis in yeast.
The build up of reactive oxygen species (ROS) is known to contribute to a reduction in the lifespan of a cell and to their degeneration in diseases such as Alzheimer's and tissue ischaemia. It is therefore important to elucidate pathways that regulate cellular oxidative stress. We have previously shown that actin dynamics can affect the oxidative-stress burden on a yeast cell and thereby its potential lifespan. To elucidate further the connection between actin dynamics and oxidative stress, we sought to identify regulators of this process. The actin regulatory proteins Sla1p and End3p are important in maintaining a rapid turnover of F-actin in cortical patches. We show that cells expressing a mutated form of Sla1p or lacking End3p display markers of apoptosis such as depolarized mitochondrial membranes and elevated levels of reactive oxygen species. Overexpression of the ubiquitin ligase RSP5 can alleviate the oxidative-stress phenotype observed in cells lacking End3p by targeting Sla1p to the cortex and restoring actin remodelling capability. We also demonstrate that overexpression of PDE2, a negative regulator of the Ras/cAMP pathway rescues actin dynamics, reduces oxidative stress sensitivity and restores viability in deltaend3 cells. Our data suggest, for the first time, that a physiological link exists between actin regulation and cAMP signalling that regulates apoptosis in yeast.
Gourlay
Campbell W
CW
Department of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.
Ayscough
Kathryn R
KR
D000199:Actins / Q000378:metabolism; D017209:Apoptosis; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport; D008928:Mitochondria / Q000378:metabolism; D009154:Mutation; D018384:Oxidative Stress; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism
D000199:Actins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C091908:END3 protein, S cerevisiae; D056827:Endosomal Sorting Complexes Required for Transport; D017382:Reactive Oxygen Species; C082265:SLA1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000242:Cyclic AMP; D043743:Ubiquitin-Protein Ligase Complexes; D010727:Phosphoric Diester Hydrolases; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; C469287:RSP5 protein, S cerevisiae