Autophagy balances mtDNA synthesis and degradation by DNA polymerase POLG during starvation

Medeiros, Tania; Thomas, Ryan Lee; Ghillebert, Ruben; Graef, Martin

doi:10.1083/jcb.201801168

Cited by 54 publications

(51 citation statements)

References 48 publications

(66 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Next, we tried to monitor mtDNA synthesis by in vivo incorporation of the thymidine analogue 5-ethynyl-2′-deoxyuridine (EdU) during the zygote development. EdU incorporation was visualized in fixed cells with Alexa Fluor 488 using copper click chemistry, following a protocol reported for Saccharomyces cerevisiae 35 . a-and α-haploid cells were transferred to hay cube agar plates supplemented with EdU and allowed to form zygotes.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Step-wise elimination of α-mitochondrial nucleoids and mitochondrial structure as a basis for the strict uniparental inheritance in Cryptococcus neoformans

Nishimura

Shikanai

Kawamoto

et al. 2020

Sci Rep

View full text Add to dashboard Cite

in most sexual eukaryotes, mitochondrial (mt) DnA is uniparentally inherited, although the detailed mechanisms underlying this phenomenon remain controversial. the most widely accepted explanations include the autophagic elimination of paternal mitochondria in the fertilized eggs and the active degradation of paternal mitochondrial DnA. to decode the precise program for the uniparental inheritance, we focused on Cryptococcus neoformans as a model system, in which mtDnA is inherited only from the a-parent, although gametes of a-and α-cells are of equal size and contribute equal amounts of mtDnA to the zygote. in this research, the process of preferential elimination of the mitochondria contributed by the α-parent (α-mitochondria) was studied by fluorescence microscopy and single cell analysis using optical tweezers, which revealed that α-mitochondria are preferentially reduced by the following three steps: (1) preferential reduction of α-mitochondrial (mt) nucleoids and α-mtDNA, (2) degradation of the α-mitochondrial structure and (3) proliferation of remaining mt nucleoids during the zygote development. furthermore, AUTOPHAGY RELATED GENE (ATG) 8 and the gene encoding mitochondrial endonuclease G (NUC1) were disrupted, and the effects of their disruption on the uniparental inheritance were scrutinized. Disruption of ATG8 (ATG7) and NUC1 did not have severe effects on the uniparental inheritance, but microscopic examination revealed that α-mitochondria lacking mt nucleoids persisted in Δatg8 zygotes, indicating that autophagy is not critical for the uniparental inheritance per se but is responsible for the clearance of mitochondrial structures after the reduction of α-mt nucleoids. Mitochondria and chloroplasts are organelles responsible for ATP production via respiration and photosynthesis, respectively. In addition, these organelles function as centers for diverse cellular processes, including lipid biosynthesis, amino acid metabolism, and cell death. Mitochondria and chloroplasts contain their own genomes, which are thought to be vestiges of their bacterial ancestors 1. Unlike nuclear DNA, one or two copies of which are present per cell, hundreds to thousands of copies of mitochondrial (mt) DNA are present in individual cells. Usually, each of the cells maintains only one genotype of mtDNA (homoplasmy), which is inherited from the maternal parent. Maternal inheritance of mitochondrial (chloroplast) genomes is commonly observed in sexual eukaryotes, including animals, plants, fungi, and protists 2-4. Uniparental/maternal inheritance was once considered to be a result of the dilution of the paternal contribution because the paternal gametes (sperm) are much smaller than maternal gametes (eggs) and contribute a limited amount of cytoplasm to the progeny 5. However, this simple dilution model has been challenged by many findings 6. Currently, various mechanisms have been proposed to explain the active elimination of paternal

show abstract

Section: Resultsmentioning

confidence: 99%

“…edU labelling of zygotes. EdU labeling was performed using a kit (Click-iT Plus Alexa488 imaging kit, Thermo Fisher Scientific, Waltham, MA USA) and following a protocol reported for S. cereviciae 35 . Mating of C. neoformans was induced on hay cube agar plates, on which 200 µL of 1 mM EdU (5′-ethynyl-2′-deoxyuridine) was spread and dried.…”

Section: Methodsmentioning

confidence: 99%

Step-wise elimination of α-mitochondrial nucleoids and mitochondrial structure as a basis for the strict uniparental inheritance in Cryptococcus neoformans

Nishimura

Shikanai

Kawamoto

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…8D). Reactive oxygen species (ROS) accumulate in autophagy-deficient cells under nitrogen starvation (42,43) and in mitophagy-deficient cells under starvation after respiratory growth (44). It is possible that ROS released from excess mitochondria accumulate in atg2⌬ or atg32⌬ cells in ethanoldepleted phase; if so, these ROS could damage cellular components in a way that inhibits rapid adaptation to fresh medium.…”

Section: Analysis Of Autophagy In Batch Culture On Low-glucose Mediummentioning

confidence: 99%

Analysis of autophagy activated during changes in carbon source availability in yeast cells

Iwama

Ohsumi

2019

Journal of Biological Chemistry

View full text Add to dashboard Cite

Autophagy is a conserved intracellular degradation system in eukaryotes. Recent studies have revealed that autophagy can be induced not only by nitrogen starvation but also by many other stimuli. However, questions persist regarding the types of conditions that induce autophagy, as well as the particular kinds of autophagy that are induced under these specific conditions. In experimental studies, abrupt nutrient changes are often used to induce autophagy. In this study, we investigated autophagy induction in batch culture on lowglucose medium, in which growth of yeast (Saccharomyces cerevisiae) cells is clearly reflected exclusively by carbon source state. In this medium, cells pass sequentially through three stages: glucose-utilizing, ethanol-utilizing, and ethanol-depleted phases. Using GFP cleavage assay by immunoblotting methods, fluorescence microscopy, and transmission electron microscopy ultrastructural analysis, we found that bulk autophagy and endoplasmic reticulum-phagy are induced starting at the ethanol-utilizing phase, and bulk autophagy is activated to a greater extent in the ethanoldepleted phase. Furthermore, we found that mitophagy is induced by ethanol depletion. Microautophagy occurred after glucose depletion and involved incorporation of cytosolic components and lipid droplets into the vacuolar lumen. Moreover, we observed that autophagy-deficient cells grow more slowly in the ethanol-utilizing phase and exhibit a delay in growth resumption when they are shifted to fresh medium from the ethanol-depleted phase. Our findings suggest that distinct types of autophagy are induced in yeast cells undergoing gradual changes in carbon source availability. 2 The abbreviations used are: PAS, pre-autophagosomal structure; BODIPY, 4,4-difluoro-1

show abstract

“…Recent work done has shown that MIP1, the yeast homolog of POLG, controls mtDNA copy number by regulating mtDNA synthesis and degradation in starving yeast cells which were deficient in Atg7 (DAtg7) [53]. Atg7 is a conserved component of the ubiquitinlike system required for autophagy in yeast [54].…”

Section: Analysis Of the Mtdna Point Mutation Load In The Livers Of Ymentioning

confidence: 99%

Mechanisms of Mitochondrial DNA Deletion Formation

2019

View full text Add to dashboard Cite

Mitochondrial DNA (mtDNA) encodes a subset of genes which are essential for oxidative phosphorylation. Deletions in the mtDNA can ablate a number of these genes, and result in mitochondrial dysfunction which is associated with bona-fide mitochondrial disorders. Although mtDNA deletions are thought to occur as a result of replication errors or following double-strand breaks, the exact mechanism(s) behind deletion formation have yet to be determined. In this review we discuss the current knowledge about the fate of mtDNA following double-strand breaks, including the molecular players which mediate

show abstract

Autophagy balances mtDNA synthesis and degradation by DNA polymerase POLG during starvation

Cited by 54 publications

References 48 publications

Step-wise elimination of α-mitochondrial nucleoids and mitochondrial structure as a basis for the strict uniparental inheritance in Cryptococcus neoformans

Step-wise elimination of α-mitochondrial nucleoids and mitochondrial structure as a basis for the strict uniparental inheritance in Cryptococcus neoformans

Analysis of autophagy activated during changes in carbon source availability in yeast cells

Mechanisms of Mitochondrial DNA Deletion Formation

Contact Info

Product

Resources

About