TY - JOUR
T1 - Differential developmental expression and cell type specificity of Dictyostelium catalases and their response to oxidative stress and UV-light
AU - Garcia, Ma Xenia U.
AU - Foote, Christopher
AU - Van Es, Saskia
AU - Devreotes, Peter N.
AU - Alexander, Stephen
AU - Alexander, Hannah
N1 - Funding Information:
This work was supported by NIH grants GM53929 to S.A. and GM28007 to P.N.D. and a grant from the Cancer Research Center, Columbia, MO, USA. M.X.U.G. was supported by a University of Missouri Molecular Biology Program predoctoral fellowship. S.A. is the recipient of an American Cancer Society Faculty Research Award (FRA448). This work is presented in partial fulfillment of the requirements for the Ph.D. degree for M.X.U.G. and C.F. at the University of Missouri. We are extremely grateful to Guochun Li and Supriya Srinivasan for advice and assistance in the course of this work and we thank Professor Abe Eisenstark for helpful discussions. We greatly appreciate receiving the cDNA clones from the Dictyostelium cDNA project in Japan and the genomic sequence data from the Sanger Centre. Thanks to Jeff Williams and Keith Williams for providing antibodies.
PY - 2000/7/24
Y1 - 2000/7/24
N2 - Cells of Dictyostelium discoideum are highly resistant to DNA damaging agents such as UV-light, γ-radiation and chemicals. The genes encoding nucleotide excision repair (NER) and base excision repair (BER) enzymes are rapidly upregulated in response to UV-irradiation and DNA-damaging chemicals, suggesting that this is at least partially responsible for the resistance of this organism to these agents. Although Dictyostelium is also unusually resistant to high concentrations of H2O2, little is known about the response of this organism to oxidative stress. To determine if transcriptional upregulation is a common mechanism for responding to DNA-damaging agents, we have studied the Dictyostelium catalase and Cu/Zn superoxide dismutase antioxidant enzymes. We show that there are two catalase genes and that each is differentially regulated both temporally and spatially during multicellular development. The catA gene is expressed throughout growth and development and its corresponding enzyme is maintained at a steady level. In contrast, the catB gene encodes a larger protein and is only expressed during the final stages of morphogenesis. Cell type fractionation showed that the CatB enzyme is exclusively localized to the prespore cells and the CatA enzyme is found exclusively in the prestalk cells. Each enzyme has a different subcellular localization. The unique developmental timing and cell type distribution suggest that the role for catB in cell differentiation is to protect the dormant spores from oxidative damage. We found that exposure to H2O2 does not result in the induction of the catalase, superoxide dismutase, NER or BER mRNAs. A mutant with greatly reduced levels of catA mRNA and enzyme has greatly increased sensitivity to H2O2 but normal sensitivity to UV. These results indicate that the natural resistance to oxidative stress is not due to an ability to rapidly raise the level of antioxidant or DNA repair enzymes and that the response to UV-light is independent from the response to reactive oxygen compounds. Copyright (C) 2000 Elsevier Science B.V.
AB - Cells of Dictyostelium discoideum are highly resistant to DNA damaging agents such as UV-light, γ-radiation and chemicals. The genes encoding nucleotide excision repair (NER) and base excision repair (BER) enzymes are rapidly upregulated in response to UV-irradiation and DNA-damaging chemicals, suggesting that this is at least partially responsible for the resistance of this organism to these agents. Although Dictyostelium is also unusually resistant to high concentrations of H2O2, little is known about the response of this organism to oxidative stress. To determine if transcriptional upregulation is a common mechanism for responding to DNA-damaging agents, we have studied the Dictyostelium catalase and Cu/Zn superoxide dismutase antioxidant enzymes. We show that there are two catalase genes and that each is differentially regulated both temporally and spatially during multicellular development. The catA gene is expressed throughout growth and development and its corresponding enzyme is maintained at a steady level. In contrast, the catB gene encodes a larger protein and is only expressed during the final stages of morphogenesis. Cell type fractionation showed that the CatB enzyme is exclusively localized to the prespore cells and the CatA enzyme is found exclusively in the prestalk cells. Each enzyme has a different subcellular localization. The unique developmental timing and cell type distribution suggest that the role for catB in cell differentiation is to protect the dormant spores from oxidative damage. We found that exposure to H2O2 does not result in the induction of the catalase, superoxide dismutase, NER or BER mRNAs. A mutant with greatly reduced levels of catA mRNA and enzyme has greatly increased sensitivity to H2O2 but normal sensitivity to UV. These results indicate that the natural resistance to oxidative stress is not due to an ability to rapidly raise the level of antioxidant or DNA repair enzymes and that the response to UV-light is independent from the response to reactive oxygen compounds. Copyright (C) 2000 Elsevier Science B.V.
KW - Cell death
KW - Cell type specific gene regulation
KW - DNA repair
KW - Peroxisome
KW - Reactive oxygen species
KW - Superoxide dismutase
UR - http://www.scopus.com/inward/record.url?scp=0034710159&partnerID=8YFLogxK
U2 - 10.1016/S0167-4781(00)00063-4
DO - 10.1016/S0167-4781(00)00063-4
M3 - Article
C2 - 11004503
AN - SCOPUS:0034710159
SN - 0167-4781
VL - 1492
SP - 295
EP - 310
JO - Biochimica et Biophysica Acta - Gene Structure and Expression
JF - Biochimica et Biophysica Acta - Gene Structure and Expression
IS - 2-3
ER -