Dataset Information

Impairment of starch biosynthesis results in elevated oxidative stress and autophagy activity in Chlamydomonas reinhardtii.

ABSTRACT: Autophagy is a self-degradation system wherein cellular materials are recycled. Although autophagy has been extensively studied in yeast and mammalian systems, integrated stress responses in microalgae remain poorly understood. Accordingly, we carried out a comparative study on the oxidative stress responses of Chlamydomonas reinhardtii wild-type and a starchless (sta6) mutant previously shown to accumulate high lipid content under adverse conditions. To our surprise, the sta6 mutant exhibited significantly higher levels of lipid peroxidation in the same growth conditions compared to controls. The sta6 mutant was more sensitive to oxidative stress induced by H2O2, whereas the wild-type was relatively more resistant. In addition, significantly up-regulated autophagy-related factors including ATG1, ATG101, and ATG8 were maintained in the sta6 mutant regardless of nitrogen availability. Also, the sta6 mutant exhibited relatively higher ATG8 protein level compared to wild-type under non-stress condition, and quickly reached a saturation point of autophagy when H2O2 was applied. Our results indicate that, in addition to the impact of carbon allocation, the increased lipid phenotype of the sta6 mutant may result from alterations in the cellular oxidative state, which in turn activates autophagy to clean up oxidatively damaged components and fuel lipid production.

SUBMITTER: Tran QG

PROVIDER: S-EPMC6614365 | biostudies-other | 2019 Jul

REPOSITORIES: biostudies-other

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Impairment of starch biosynthesis results in elevated oxidative stress and autophagy activity in Chlamydomonas reinhardtii.

Tran Quynh-Giao QG Cho Kichul K Park Su-Bin SB Kim Urim U Lee Yong Jae YJ Kim Hee-Sik HS

Scientific reports 20190708 1

Autophagy is a self-degradation system wherein cellular materials are recycled. Although autophagy has been extensively studied in yeast and mammalian systems, integrated stress responses in microalgae remain poorly understood. Accordingly, we carried out a comparative study on the oxidative stress responses of Chlamydomonas reinhardtii wild-type and a starchless (sta6) mutant previously shown to accumulate high lipid content under adverse conditions. To our surprise, the sta6 mutant exhibited s ...[more]

PMID: 31285472

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Project description:Acclimation to singlet oxygen was shown to induce various oxidative stress response genes of which some were also strongly overexpressed in the singlet oxygen resistant mutant sor1. Because sor1 was also more tolerant to other oxidative and electrophilic stress conditions, and because many of the sor1 overexpressed genes are known to be involved in the detoxification of reactive electrophile species, the response of the C. reinhardtii wild-type strain to various oxidative and electrophilic stress conditions was determined. Therefore, cultures were exposed to the reactive oxygen species-producing photosensitizer neutral red, the organic hydroperoxide tert-butylhydroperoxide, the photosynthetic herbicide 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) and the lipophilic electrophile 2(E)-Hexenal for two hours and the global genetic response was analyzed. Cluster analysis revealed the most similar expression pattern between DBMIB and 2(E)-Hexenal and to a lower degree between NR and tBOOH. Still, there were many common induced genes including several of the oxidative stress response and detoxification genes overexpressed in the sor1 mutant. The 4A+ wild-type strain was grown mixotrophically in a Tris-acetate phosphate to a density of 2x10^6 cells/ml. Then cultures were split into 20 ml subcultures, and exposed to either of the four chemicals DBMIB (2 µM), 2(E)-Hexenal (0.3 mM), neutral red (NR, 3 µM), tert-butylhydroperoxide (tBOOH, 100 µM) or no chemical (control) for 2 hours, in three independent biological replicates. The cells of each replicate were harvested by centrifugation and total RNA was isolated using the RNeasy Mini Kit (Qiagen). DNA microarrays were performed using the ‘One-Color Microarray-Based Gene Expression Analysis’ system and a custom made 4 × 44 K ‘Chlamydomonas Whole Genome DNA Microarrays’ (Agilent Technologies) containing 15143 specific probes designed based on the Chlamydomonas version 4.0 transcript models provided by the DOE Joint Genome Institute (JGI), with an average of three replicates for each probe

Dataset Information

Impairment of starch biosynthesis results in elevated oxidative stress and autophagy activity in Chlamydomonas reinhardtii.

Publications

Impairment of starch biosynthesis results in elevated oxidative stress and autophagy activity in Chlamydomonas reinhardtii.

Similar Datasets

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