Autophagy promotes photomorphogenesis during seedling development in Arabidopsis in carbon limiting conditions

Autophagy is a conserved catabolic process that plays an essential role under nutrient starvation conditions and influences different developmental processes. We observed that seedlings of autophagy mutants (atg2, atg5, atg7, and atg9) germinated in the dark showed delayed chloroplast development following illumination. The delayed chloroplast development was characterized by a decrease in photosynthetic and chlorophyll biosynthetic proteins, lower chlorophyll content, reduced chloroplast size, and increased levels of proteins involved in lipid biosynthesis. Confirming the biological impact of these differences, photosynthetic performance was impaired in autophagy mutants 12h post illumination. We investigated if the delayed chloroplast development could be explained by lower lipid import to the chloroplast or lower triglyceride (TAG) turnover. We observed that the limitations in the chloroplast lipid import imposed by trigalactosyldiacylglycerol1 are unlikely to explain the delay in photomorphogenesis. However, we found that lower TAG mobility in the triacylglycerol lipase mutant sugardependent1 significantly affected photomorphogenesis. Moreover, we showed that lower levels of carbon resources exacerbated the delay in photomorphogenesis whereas higher levels of carbon resources had an opposite effect. This work provides evidence that autophagic process operate during de-etiolation in a manner that contributes to photomorphogenesis through increasing lipid turnover to physically or energetically sustain photomorphogenesis.

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Fatty acid synthase is preferentially degraded by autophagy upon nitrogen starvation in yeast

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1409476112 ◽

2015 ◽

Vol 112 (5) ◽

pp. 1434-1439 ◽

Cited By ~ 41

Author(s):

Tomer Shpilka ◽

Evelyn Welter ◽

Noam Borovsky ◽

Nira Amar ◽

Frida Shimron ◽

...

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthase ◽

Nitrogen Starvation ◽

Dependent Manner ◽

Nitrogen Deprivation ◽

Selective Autophagy ◽

Evolutionarily Conserved ◽

Specific Proteins ◽

Catabolic Process ◽

Starvation Conditions

Autophagy, an evolutionarily conserved intracellular catabolic process, leads to the degradation of cytosolic proteins and organelles in the vacuole/lysosome. Different forms of selective autophagy have recently been described. Starvation-induced protein degradation, however, is considered to be nonselective. Here we describe a novel interaction between autophagy-related protein 8 (Atg8) and fatty acid synthase (FAS), a pivotal enzymatic complex responsible for the entire synthesis of C16- and C18-fatty acids in yeast. We show that although FAS possesses housekeeping functions, under starvation conditions it is delivered to the vacuole for degradation by autophagy in a Vac8- and Atg24-dependent manner. We also provide evidence that FAS degradation is essential for survival under nitrogen deprivation. Our results imply that during nitrogen starvation specific proteins are preferentially recruited into autophagosomes

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Abundance of metalloprotease FtsH12 modulates chloroplast development in Arabidopsis thaliana

Journal of Experimental Botany ◽

10.1093/jxb/eraa550 ◽

2020 ◽

Author(s):

Kati Mielke ◽

Raik Wagner ◽

Laxmi S Mishra ◽

Fatih Demir ◽

Andreas Perrar ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Protein Import ◽

Chloroplast Development ◽

Protein Translocation ◽

Seedling Development ◽

Temperature Sensitive ◽

Label Free ◽

Plastid Development ◽

Motor Complex ◽

Interaction Partners

Abstract The ATP-dependent metalloprotease FtsH12 (filamentation temperature sensitive protein H 12) has been suggested to participate in a heteromeric motor complex, driving protein translocation into the chloroplast. FtsH12 was immuno-detected in proplastids, seedlings, leaves, and roots. Expression of Myc-tagged FtsH12 under its native promotor allowed identification of FtsHi1, 2, 4, and 5, and plastidic NAD-malate dehydrogenase, five of the six interaction partners in the suggested import motor complex. Arabidopsis thaliana mutant seedlings with reduced FTSH12 abundance exhibited pale cotyledons and small, deformed chloroplasts with altered thylakoid structure. Mature plants retained these chloroplast defects, resulting in slightly variegated leaves and lower chlorophyll content. Label-free proteomics revealed strong changes in the proteome composition of FTSH12 knock-down seedlings, reflecting impaired plastid development. The composition of the translocon on the inner chloroplast membrane (TIC) protein import complex was altered, with coordinated reduction of the FtsH12-FtsHi complex subunits and accumulation of the 1 MDa TIC complex subunits TIC56, TIC214 and TIC22-III. FTSH12 overexpressor lines showed no obvious phenotype, but still displayed distinct differences in their proteome. N-terminome analyses further demonstrated normal proteolytic maturation of plastid-imported proteins irrespective of FTSH12 abundance. Together, our data suggest that FtsH12 has highest impact during seedling development; its abundance alters the plastid import machinery and impairs chloroplast development.

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Exit from the Golgi Is Required for the Expansion of the Autophagosomal Phagophore in Yeast Saccharomyces cerevisiae

Molecular Biology of the Cell ◽

10.1091/mbc.e09-04-0345 ◽

2010 ◽

Vol 21 (13) ◽

pp. 2270-2284 ◽

Cited By ~ 126

Author(s):

Aniek van der Vaart ◽

Janice Griffith ◽

Fulvio Reggiori

Keyword(s):

Lipid Bilayers ◽

Golgi Complex ◽

Critical Role ◽

Membrane Vesicles ◽

Yeast Saccharomyces Cerevisiae ◽

New Class ◽

Adp Ribosylation Factor ◽

Catabolic Process ◽

Starvation Conditions

The delivery of proteins and organelles to the vacuole by autophagy involves membrane rearrangements that result in the formation of large vesicles called autophagosomes. The mechanism underlying autophagosome biogenesis and the origin of the membranes composing these vesicles remains largely unclear. We have investigated the role of the Golgi complex in autophagy and have determined that in yeast, activation of ADP-ribosylation factor (Arf)1 and Arf2 GTPases by Sec7, Gea1, and Gea2 is essential for this catabolic process. The two main events catalyzed by these components, the biogenesis of COPI- and clathrin-coated vesicles, do not play a critical role in autophagy. Analysis of the sec7 strain under starvation conditions revealed that the autophagy machinery is correctly assembled and the precursor membrane cisterna of autophagosomes, the phagophore, is normally formed. However, the expansion of the phagophore into an autophagosome is severely impaired. Our data show that the Golgi complex plays a crucial role in supplying the lipid bilayers necessary for the biogenesis of double-membrane vesicles possibly through a new class of transport carriers or a new mechanism.

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Selective Autophagy as a Potential Therapeutic Target in Age-Associated Pathologies

Metabolites ◽

10.3390/metabo11090588 ◽

2021 ◽

Vol 11 (9) ◽

pp. 588

Author(s):

Margarita-Elena Papandreou ◽

Nektarios Tavernarakis

Keyword(s):

Therapeutic Interventions ◽

Autophagic Flux ◽

Pharmacological Agents ◽

Selective Autophagy ◽

Age Related ◽

Pharmacological Targets ◽

Autophagic Process ◽

Severe Pathology ◽

Progressive Accumulation ◽

Catabolic Process

Progressive accumulation of damaged cellular constituents contributes to age-related diseases. Autophagy is the main catabolic process, which recycles cellular material in a multitude of tissues and organs. Autophagy is activated upon nutrient deprivation, and oncogenic, heat or oxidative stress-induced stimuli to selectively degrade cell constituents and compartments. Specificity and accuracy of the autophagic process is maintained via the precision of interaction of autophagy receptors or adaptors and substrates by the intricate, stepwise orchestration of specialized integrating stimuli. Polymorphisms in genes regulating selective autophagy have been linked to aging and age-associated disorders. The involvement of autophagy perturbations in aging and disease indicates that pharmacological agents balancing autophagic flux may be beneficial, in these contexts. Here, we introduce the modes and mechanisms of selective autophagy, and survey recent experimental evidence of dysfunctional autophagy triggering severe pathology. We further highlight identified pharmacological targets that hold potential for developing therapeutic interventions to alleviate cellular autophagic cargo burden and associated pathologies.

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Epigenetic Regulation of Autophagy Beyond the Cytoplasm: A Review

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.675599 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yin Shi ◽

Han-Ming Shen ◽

Vidya Gopalakrishnan ◽

Nancy Gordon

Keyword(s):

Signaling Pathways ◽

Epigenetic Regulation ◽

Mtor Signaling ◽

Stress Conditions ◽

Regulatory Mechanisms ◽

Control Mechanisms ◽

Regulatory Pathways ◽

The Face ◽

Autophagic Process ◽

Catabolic Process

Autophagy is a highly conserved catabolic process induced under various stress conditions to protect the cell from harm and allow survival in the face of nutrient- or energy-deficient states. Regulation of autophagy is complex, as cells need to adapt to a continuously changing microenvironment. It is well recognized that the AMPK and mTOR signaling pathways are the main regulators of autophagy. However, various other signaling pathways have also been described to regulate the autophagic process. A better understanding of these complex autophagy regulatory mechanisms will allow the discovery of new potential therapeutic targets. Here, we present a brief overview of autophagy and its regulatory pathways with emphasis on the epigenetic control mechanisms.

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Can the Academic Self-Concept be Positive and Realistic?

Zeitschrift für Pädagogische Psychologie ◽

10.1024/1010-0652.19.3.132 ◽

2005 ◽

Vol 19 (3) ◽

pp. 129-132 ◽

Cited By ~ 6

Author(s):

Reimer Kornmann

Keyword(s):

Academic Performance ◽

Opposite Effect ◽

Self Esteem ◽

Point Of View ◽

The Other ◽

Self Concept ◽

High Ability ◽

Self Image ◽

Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

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I Like Her, Because I Like Myself: Self-Evaluation as a Source of Interpersonal Attitudes

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1026//1618-3169.50.4.239 ◽

2003 ◽

Vol 50 (4) ◽

pp. 239-246 ◽

Cited By ~ 30

Author(s):

Eva Walther ◽

Claudia Trasselli

Keyword(s):

Opposite Effect ◽

Learning Phase ◽

The Self ◽

Attitude Formation ◽

Formation Processes ◽

False Feedback ◽

Self Evaluation ◽

Evaluation Group ◽

Group A ◽

The Difference

Abstract. Two experiments tested the hypothesis that self-evaluation can serve as a source of interpersonal attitudes. In the first study, self-evaluation was manipulated by means of false feedback. A subsequent learning phase demonstrated that the co-occurrence of the self with another individual influenced the evaluation of this previously neutral target. Whereas evaluative self-target similarity increased under conditions of negative self-evaluation, an opposite effect emerged in the positive self-evaluation group. A second study replicated these findings and showed that the difference between positive and negative self-evaluation conditions disappeared when a load manipulation was applied. The implications of self-evaluation for attitude formation processes are discussed.

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