scholarly journals Enhanced survival of Drosophila Akt1 hypomorphs during amino-acid starvation requires foxo

Genome ◽  
2016 ◽  
Vol 59 (2) ◽  
pp. 87-93 ◽  
Author(s):  
Jennifer D. Slade ◽  
Brian E. Staveley
Keyword(s):  
Amino Acid ◽  
Disordered Eating ◽  
Amino Acid Starvation ◽  
Central Component ◽  
Receptor Signalling ◽  
Drosophila Model ◽  
Insulin Receptor Signalling ◽  
Severe Reduction ◽  
Mutant Lines

Disordered eating includes any pattern of irregular eating that may lead to either extreme weight loss or obesity. The conserved insulin receptor signalling pathway acts to regulate energy balance and nutrient intake, and its central component Akt1 and endpoint effector foxo are pivotal for survival during nutritional stress. Recently generated Akt1 hypomorphic mutant lines exhibit a moderate decrease in lifespan when aged upon standard media, yet show a considerable increase in survival upon amino-acid starvation media. While the loss of foxo function significantly reduces the survival response to amino-acid starvation, a combination of these Akt1 hypomorphs and a null foxo mutation reveal a synergystic and severe reduction in lifespan upon standard media, and an epistatic relationship when undergoing amino-acid starvation. Evaluation of survivorship upon amino-acid starvation media of these double mutants indicate a phenotype similar to the original foxo mutant demonstrating the role of foxo in this Akt1 phenotype. These results indicate that the subtle manipulation of foxo through Akt1 can enhance survival during adverse nutrient conditions to model the ability of individuals to tolerate nutrient deprivation. Ultimately, we believe that a Drosophila model of disordered eating could generate new avenues to develop potential therapies for related human conditions.

scholarly journals Deubiquitinating enzyme USP30 maintains basal peroxisome abundance by regulating pexophagy

2019 ◽  
Vol 218 (3) ◽  
pp. 798-807 ◽  
Author(s):  
Victoria Riccio ◽  
Nicholas Demers ◽  
Rong Hua ◽  
Miluska Vissa ◽  
Derrick T. Cheng ◽  
...  
Keyword(s):  
Amino Acid ◽  
Ubiquitin Ligase ◽  
Cell Function ◽  
E3 Ubiquitin Ligase ◽  
Metabolic Stress ◽  
Amino Acid Starvation ◽  
Deubiquitinating Enzyme ◽  
Potential Therapeutic Target ◽  
Autophagic Degradation

The regulation of organelle abundance is critical for cell function and survival; however, the mechanisms responsible are not fully understood. In this study, we characterize a role of the deubiquitinating enzyme USP30 in peroxisome maintenance. Peroxisomes are highly dynamic, changing in abundance in response to metabolic stress. In our recent study identifying the role of USP30 in mitophagy, we observed USP30 to be localized to punctate structures resembling peroxisomes. We report here that USP30, best known as a mitophagy regulator, is also necessary for regulating pexophagy, the selective autophagic degradation of peroxisomes. We find that overexpressing USP30 prevents pexophagy during amino acid starvation, and its depletion results in pexophagy induction under basal conditions. We demonstrate that USP30 prevents pexophagy by counteracting the action of the peroxisomal E3 ubiquitin ligase PEX2. Finally, we show that USP30 can rescue the peroxisome loss observed in some disease-causing peroxisome mutations, pointing to a potential therapeutic target.

Role of the APS adapter protein in insulin receptor signalling

2000 ◽  
Vol 28 (5) ◽  
pp. A270-A270
Author(s):  
Z. Ahmed ◽  
B. J. Smith ◽  
P. Wylie ◽  
T. S. Pillay
Keyword(s):  
Insulin Receptor ◽  
Adapter Protein ◽  
Receptor Signalling ◽  
Insulin Receptor Signalling

scholarly journals In vivo vizualisation of mono-ADP-ribosylation by dPARP16 upon amino-acid starvation

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Angelica Aguilera-Gomez ◽  
Marinke M van Oorschot ◽  
Tineke Veenendaal ◽  
Catherine Rabouille
Keyword(s):  
Amino Acid ◽  
Metabolic Stress ◽  
Amino Acid Starvation ◽  
Critical Event ◽  
Post Translational Modification ◽  
Adp Ribosylation ◽  
Body Component ◽  
Necessary And Sufficient

PARP catalysed ADP-ribosylation is a post-translational modification involved in several physiological and pathological processes, including cellular stress. In order to visualise both Poly-, and Mono-, ADP-ribosylation in vivo, we engineered specific fluorescent probes. Using them, we show that amino-acid starvation triggers an unprecedented display of mono-ADP-ribosylation that governs the formation of Sec body, a recently identified stress assembly that forms in Drosophila cells. We show that dPARP16 catalytic activity is necessary and sufficient for both amino-acid starvation induced mono-ADP-ribosylation and subsequent Sec body formation and cell survival. Importantly, dPARP16 catalyses the modification of Sec16, a key Sec body component, and we show that it is a critical event for the formation of this stress assembly. Taken together our findings establish a novel example for the role of mono-ADP-ribosylation in the formation of stress assemblies, and link this modification to a metabolic stress.

scholarly journals Diverse Energy-Conserving Pathways in Clostridium difficile: Growth in the Absence of Amino Acid Stickland Acceptors and the Role of the Wood-Ljungdahl Pathway

2020 ◽  
Vol 202 (20) ◽  
Author(s):  
Simonida Gencic ◽  
David A. Grahame
Keyword(s):  
Amino Acid ◽  
Clostridium Difficile ◽  
Central Component ◽  
Content Increase ◽  
Efficient System ◽  
Content Type ◽  
Atp Production ◽  
Cell Extracts ◽  
Complete Set

ABSTRACT Clostridium difficile is the leading cause of hospital-acquired antibiotic-associated diarrhea and is the only widespread human pathogen that contains a complete set of genes encoding the Wood-Ljungdahl pathway (WLP). In acetogenic bacteria, synthesis of acetate from 2 CO2 molecules by the WLP functions as a terminal electron accepting pathway; however, C. difficile contains various other reductive pathways, including a heavy reliance on Stickland reactions, which questions the role of the WLP in this bacterium. In rich medium containing high levels of electron acceptor substrates, only trace levels of key WLP enzymes were found; therefore, conditions were developed to adapt C. difficile to grow in the absence of amino acid Stickland acceptors. Growth conditions were identified that produce the highest levels of WLP activity, determined by Western blot analyses of the central component acetyl coenzyme A synthase (AcsB) and assays of other WLP enzymes. Fermentation substrate and product analyses, enzyme assays of cell extracts, and characterization of a ΔacsB mutant demonstrated that the WLP functions to dispose of metabolically generated reducing equivalents. While WLP activity in C. difficile does not reach the levels seen in classical acetogens, coupling of the WLP to butyrate formation provides a highly efficient system for regeneration of NAD+ “acetobutyrogenesis,” requiring only low flux through the pathways to support efficient ATP production from glucose oxidation. Additional insights redefine the amino acid requirements in C. difficile, explore the relationship of the WLP to toxin production, and provide a rationale for colocalization of genes involved in glycine synthesis and cleavage within the WLP operon. IMPORTANCE Clostridium difficile is an anaerobic, multidrug-resistant, toxin-producing pathogen with major health impacts worldwide. It is the only widespread pathogen harboring a complete set of Wood-Ljungdahl pathway (WLP) genes; however, the role of the WLP in C. difficile is poorly understood. In other anaerobic bacteria and archaea, the WLP can operate in one direction to convert CO2 to acetic acid for biosynthesis or in either direction for energy conservation. Here, conditions are defined in which WLP levels in C. difficile increase markedly, functioning to support metabolism of carbohydrates. Amino acid nutritional requirements were better defined, with new insight into how the WLP and butyrate pathways act in concert, contributing significantly to energy metabolism by a mechanism that may have broad physiological significance within the group of nonclassical acetogens.

scholarly journals Superinfection Exclusion by p28 of Turnip Crinkle Virus Is Separable from Its Replication Function

2020 ◽  
Vol 33 (2) ◽  
pp. 364-375
Author(s):  
Qin Guo ◽  
Shaoyan Zhang ◽  
Rong Sun ◽  
Xiaolong Yao ◽  
Xiao-Feng Zhang ◽  
...  
Keyword(s):  
Amino Acid ◽  
Single Amino Acid ◽  
Turnip Crinkle Virus ◽  
Superinfection Exclusion ◽  
Protein Levels ◽  
Severe Reduction ◽  
Amino Acid Mutations ◽  
Concentration Threshold ◽  
Replication Function

We recently reported that the p28 auxiliary replication protein encoded by turnip crinkle virus (TCV) is also responsible for eliciting superinfection exclusion (SIE) against superinfecting TCV. However, it remains unresolved whether the replication function of p28 could be separated from its ability to elicit SIE. Here, we report the identification of two single amino acid mutations that decouple these two functions. Using an Agrobacterium infiltration-based delivery system, we transiently expressed a series of p28 deletion and point mutants, and tested their ability to elicit SIE against a cointroduced TCV replicon. We found that substituting alanine (A) for valine (V) and phenylalanine (F) at p28 positions 181 and 182, respectively, modestly compromised SIE in transiently expressed p28 derivatives. Upon incorporation into TCV replicons, V181A and F182A decoupled TCV replication and SIE diametrically. Although V181A impaired SIE without detectably compromising replication, F182A abolished TCV replication but had no effect on SIE once the replication of the defective replicon was restored through complementation. Both mutations diminished accumulation of p28 protein, suggesting that p28 must reach a concentration threshold in order to elicit a strong SIE. Importantly, the severe reduction of F182A protein levels correlated with a dramatic loss in the number of intracellular p28 foci formed by p28–p28 interactions. Together, these findings not only decouple the replication and SIE functions of p28 but also unveil a concentration dependence for p28 coalescence and SIE elicitation. These data further highlight the role of p28 multimerization in driving the exclusion of secondary TCV infections.

scholarly journals Cleavage of mRNAs and role of tmRNA system under amino acid starvation in Escherichia coli

2008 ◽  
Vol 68 (2) ◽  
pp. 462-473 ◽  
Author(s):  
Xia Li ◽  
Mieko Yagi ◽  
Teppei Morita ◽  
Hiroji Aiba
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Starvation

scholarly journals The role of autophagy in neonatal tissues: Just a response to amino acid starvation?

Autophagy ◽  
2008 ◽  
Vol 4 (5) ◽  
pp. 727-730 ◽  
Author(s):  
Stefano Schiaffino ◽  
Cristina Mammucari ◽  
Marco Sandri
Keyword(s):  
Amino Acid ◽  
Amino Acid Starvation

Lipid Response to Amino Acid Starvation in Fat Cells: Role of FGF21

2017 ◽  
pp. 1-17
Author(s):  
Albert Pérez-Martí ◽  
Pedro F. Marrero ◽  
Diego Haro ◽  
Joana Relat
Keyword(s):  
Amino Acid ◽  
Amino Acid Starvation ◽  
Fat Cells ◽  
Lipid Response

scholarly journals Global Role of the Protein Kinase Gcn2 in the Human Pathogen Candida albicans

2005 ◽  
Vol 4 (10) ◽  
pp. 1687-1696 ◽  
Author(s):  
Hélène Tournu ◽  
Gyanendra Tripathi ◽  
Gwyneth Bertram ◽  
Susan Macaskill ◽  
Abigail Mavor ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Amino Acid ◽  
Amino Acid Starvation ◽  
Transcriptional Level ◽  
General Amino Acid Control ◽  
Acid Control ◽  
Eif2α Kinase ◽  
Starvation Conditions ◽  
Human Pathogen Candida Albicans

ABSTRACT The pathogen Candida albicans responds to amino acid starvation by activating pseudohyphal development and the expression of amino acid biosynthetic genes (GCN response). In Saccharomyces cerevisiae, the GCN response is dependent on Gcn2, which regulates the translation of the transcription factor Gcn4. Therefore, we examined the role of Gcn2 in C. albicans by using molecular, cellular, and genomic approaches. We show that C. albicans GCN2 encodes an eIF2α kinase, like its S. cerevisiae homologue. However, GCN4 appears to be regulated mainly at the transcriptional level in C. albicans. Furthermore, the inactivation of C. albicans Gcn2 only partially attenuates growth under amino acid starvation conditions and resistance to the histidine analogue 3-aminotriazole. Our comparison of the Gcn4 and Gcn2 regulons by transcript profiling reinforces the view that Gcn2 contributes to, but is not essential for, the activation of general amino acid control in C. albicans.

scholarly journals Crystal structures of GCN2 C-terminal domain: Insight into GCN2 regulation

2014 ◽  
Vol 70 (a1) ◽  
pp. C1407-C1407
Author(s):  
Isha Singh ◽  
Hongzhen He ◽  
Sheree Wek ◽  
Souvik Dey ◽  
Thomas Baird ◽  
...  
Keyword(s):  
Amino Acid ◽  
Crystal Structures ◽  
Kinase Domain ◽  
Trna Synthetase ◽  
Amino Acid Starvation ◽  
Nucleic Acid Binding ◽  
Serine Threonine Kinase ◽  
Functional Studies ◽  
Terminal Domain

General control non-derepressible 2 kinase (GCN2) is a serine threonine kinase that curtails translation in response to diverse stress stimuli [1]. It is a primary sensor of amino acid starvation and mediates translation repression by phosphorylating eIF2 [2]. In addition to the kinase domain, GCN2 contains two regulatory regions; a histidyl-tRNA synthetase-like domain (HisRS) and a C-terminal domain (CTD), which function together to sense nutrient depletion. Both domains have been proposed to bind uncharged tRNA's that accumulate during amino acid starvation followed by dimerization of the kinase domain facilitating activation of GCN2 [3]. Thus, while the CTD plays an important regulatory role in activating GCN2, information on how the CTD facilitates dimerization and whether the CTD plays a similar role in murine GCN2 is limited. Moreover, the sequences of vertebrate CTDs share less than 10% sequence identity with their yeast counterpart; therefore, it is not known whether regulatory mechanisms in GCN2 are conserved across different species. We present here the experimentally phased crystal structures of murine CTD at 1.9 Å and yeast CTD at 1.95 Å. Both murine and yeast CTDs share a novel interdigitated dimeric organization, although the dimeric structures differ somewhat in overall shape and size. Additional biochemical analysis of the murine CTD confirms an important role for dimerization in its activation. Moreover, functional studies reveal that both yeast and murine GCN2 have similar nucleic acid binding properties, but mGCN2 does not appear to exhibit ribosomal association, a key feature in the model for regulation of yeast GCN2, suggesting that there are regulatory differences between the murine GCN2 and its yeast counterpart. Our data provides a basis for understanding the role of the CTD in regulation of GCN2 in both yeast and mammals.

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