TY - JOUR
T1 - Dehydroascorbate
T2 - A possible surveillance molecule of oxidative stress and programmed cell death in the green alga Chlamydomonas reinhardtii
AU - Murik, Omer
AU - Elboher, Ahinoam
AU - Kaplan, Aaron
PY - 2014/4
Y1 - 2014/4
N2 - Chlamydomonas reinhardtii tolerates relatively high H2O2 levels that induce an array of antioxidant activities. However, rather than rendering the cells more resistant to oxidative stress, the cells become far more sensitive to an additional H2O2 dose. If H2O2 is provided 1.5-9 h after an initial dose, it induces programmed cell death (PCD) in the wild-type, but not in the dum1 mutant impaired in the mitochondrial respiratory complex III. This mutant does not exhibit a secondary oxidative burst 4-5 h after the inducing H2O2, nor does it activate metacaspase-1 after the second H2O2 treatment. The intracellular dehydroascorbate level, a product of ascorbate peroxidase, increases under conditions leading to PCD. The addition of dehydroascorbate induces PCD in the wild-type and dum1 cultures, but higher levels are required in dum1 cells, where it is metabolized faster. The application of dehydroascorbate induces the expression of metacaspase-2, which is much stronger than the expression of metacaspase-1. The presence or absence of oxidative stress, in addition to the rise in internal dehydroascorbate, may determine which metacaspase is activated during Chlamydomonas PCD. Cell death is strongly affected by the timing of H2O2 or dehydroascorbate admission to synchronously grown cultures, suggesting that the cell cycle phase may distinguish cells that perish from those that do not.
AB - Chlamydomonas reinhardtii tolerates relatively high H2O2 levels that induce an array of antioxidant activities. However, rather than rendering the cells more resistant to oxidative stress, the cells become far more sensitive to an additional H2O2 dose. If H2O2 is provided 1.5-9 h after an initial dose, it induces programmed cell death (PCD) in the wild-type, but not in the dum1 mutant impaired in the mitochondrial respiratory complex III. This mutant does not exhibit a secondary oxidative burst 4-5 h after the inducing H2O2, nor does it activate metacaspase-1 after the second H2O2 treatment. The intracellular dehydroascorbate level, a product of ascorbate peroxidase, increases under conditions leading to PCD. The addition of dehydroascorbate induces PCD in the wild-type and dum1 cultures, but higher levels are required in dum1 cells, where it is metabolized faster. The application of dehydroascorbate induces the expression of metacaspase-2, which is much stronger than the expression of metacaspase-1. The presence or absence of oxidative stress, in addition to the rise in internal dehydroascorbate, may determine which metacaspase is activated during Chlamydomonas PCD. Cell death is strongly affected by the timing of H2O2 or dehydroascorbate admission to synchronously grown cultures, suggesting that the cell cycle phase may distinguish cells that perish from those that do not.
KW - Algae
KW - Ascorbate peroxidase
KW - Oxidative stress
KW - Population dynamics
KW - Programmed cell death (PCD)
UR - http://www.scopus.com/inward/record.url?scp=84896545736&partnerID=8YFLogxK
U2 - 10.1111/nph.12649
DO - 10.1111/nph.12649
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C2 - 24345283
AN - SCOPUS:84896545736
SN - 0028-646X
VL - 202
SP - 471
EP - 484
JO - New Phytologist
JF - New Phytologist
IS - 2
ER -