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Transcriptional regulation by Pho23 modulates the frequency of autophagosome formation.

ABSTRACT: Autophagy as a conserved degradation and recycling machinery is important in normal development and physiology, and defects in this process are linked to many kinds of disease. Because too much or too little autophagy can be detrimental, the process must be tightly regulated both temporally and in magnitude. The transcriptional induction and repression of the autophagy-related (ATG) genes is one crucial aspect of this regulation, but the transcriptional regulators that modulate autophagy are not well characterized. In this study, we identified Pho23 as a master transcriptional repressor for autophagy, with transcriptome profiling revealing that ATG9 is one of the key target genes. Physiological studies with a PHO23 null mutant, or with strains expressing modulated levels of Atg9, demonstrate a critical role of this protein as a regulator of autophagosome formation frequency; Atg9 protein levels correlate with the number of autophagosomes generated upon autophagy induction, and the level of autophagy activity.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE57031 | GEO | 2014/04/24

SECONDARY ACCESSION(S): PRJNA245237

REPOSITORIES: GEO

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Transcriptional regulation by Pho23 modulates the frequency of autophagosome formation.

Project description:Autophagy as a conserved degradation and recycling machinery is important in normal development and physiology, and defects in this process are linked to many kinds of disease. Because too much or too little autophagy can be detrimental, the process must be tightly regulated both temporally and in magnitude. The transcriptional induction and repression of the autophagy-related (ATG) genes is one crucial aspect of this regulation, but the transcriptional regulators that modulate autophagy are not well characterized. In this study, we identified Pho23 as a master transcriptional repressor for autophagy, with transcriptome profiling revealing that ATG9 is one of the key target genes. Physiological studies with a PHO23 null mutant, or with strains expressing modulated levels of Atg9, demonstrate a critical role of this protein as a regulator of autophagosome formation frequency; Atg9 protein levels correlate with the number of autophagosomes generated upon autophagy induction, and the level of autophagy activity. WT yeast and pho23 deletion mutants were grown under nutrient rich or nitrogen starvation conditions; gene expression was quantified across these 4 samples.

2014-04-24 | E-GEOD-57031 | biostudies-arrayexpress

The Plant Unique ESCRT Component FREE1 Regulates Autophagosome Closure

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Nonuple atg8 mutant provides genetic evidence for functional specialization of ATG8 isoforms in Arabidopsis thaliana

Project description:Autophagy is a vital cellular process that maintains organismal health by recycling damaged or superfluous cellular components within autophagosomes. This process is mediated by conserved ATG proteins, which coordinate autophagosome biogenesis and selective cargo degradation. Among these, the ubiquitin-like ATG8 protein plays a central role by linking cargo to the growing autophagosomes through interactions with selective autophagy receptors. Unlike most ATG proteins, which are represented by single or few isoforms, the ATG8 gene family is expanded in vascular plants, yet the extent of functional specialization within ATG8 isoforms remains largely unknown. Using transcriptional and translational reporters in Arabidopsis thaliana, we revealed that ATG8 isoforms are differentially expressed across tissues and form distinct autophagosomes within the same cell. To explore ATG8 specialization, we generated the nonuple Δatg8mutant lacking all nine ATG8 isoforms. The mutant displayed hypersensitivity to carbon and nitrogen starvation, coupled with defects in bulk and selective autophagy as shown by biochemical and ultrastructural analyses. Complementation experiments demonstrated that ATG8A could rescue both carbon and nitrogen starvation phenotypes, whereas ATG8H could only complement carbon starvation. Proximity labeling proteomics further identified isoform-specific interactors under nitrogen starvation, underscoring their functional divergence. These findings provide genetic evidence for the specialization of ATG8 isoforms in plants and lay a foundation for investigating their roles in diverse cell types and stress conditions.

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