Aims: Cells have developed quality control systems for protection against proteotoxicity. Misfolded and aggregation-prone proteins, which are behind the initiation and progression of many neurodegenerative diseases (ND), are known to challenge the proteostasis network of the cells. We aimed to explore the role of DNJ-27/ ERdj5, an endoplasmic reticulum (ER)-resident thioredoxin protein required as a disulfide reductase for the degradation of misfolded proteins, in well-established Caenorhabditis elegans models of Alzheimer, Parkinson and Huntington diseases. Results: We demonstrate that DNJ-27 is an ER luminal protein and that its expression is induced upon ER stress via IRE-1/XBP-1. When dnj-27 expression is downregulated by RNA interference we find an increase in the aggregation and associated pathological phenotypes (paralysis and motility impairment) caused by human b-amyloid peptide (Ab), a-synuclein (a-syn) and polyglutamine (polyQ) proteins. In turn, DNJ-27 overexpression ameliorates these deleterious phenotypes. Surprisingly, despite being an ER-resident protein, we show that dnj-27 downregulation alters cytoplasmic protein homeostasis and causes mitochondrial fragmentation. We further demonstrate that DNJ-27 overexpression substantially protects against the mitochondrial fragmentation caused by human Ab and a-syn peptides in these worm models. Innovation: We identify C. elegans dnj-27 as a novel protective gene for the toxicity associated with the expression of human Ab, a-syn and polyQ proteins, implying a protective role of ERdj5 in Alzheimer, Parkinson and Huntington diseases. Conclusion: Our data support a scenario where the levels of DNJ-27/ERdj5 in the ER impact cytoplasmic protein homeostasis and the integrity of the mitochondrial network which might underlie its protective effects in models of proteotoxicity associated to human ND. Antioxid. Redox Signal. 20,[217][218][219][220][221][222][223][224][225][226][227][228][229][230][231][232][233][234][235]

Aversive learning is fundamental for animals to increase chances of survival. In addition to classical neurotransmitters, neuropeptides have emerged to modulate such complex behaviors. Among them, neuropeptide Y (NPY) is well known to promote aversive memory acquisition in mammals. Here we identify an NPY/neuropeptide F (NPF)-related neuropeptide system in Caenorhabditis elegans and show that this FLP-34/NPR-11 system is required for learning negative associations, a process that is reminiscent of NPY signaling in mammals. The Caenorhabditis elegans NPY/NPF ortholog FLP-34 displays conserved structural hallmarks of bilaterian-wide NPY/NPF neuropeptides. We show that it is required for aversive olfactory learning after pairing diacetyl with the absence of food, but not for appetitive olfactory learning in response to butanone. To mediate diacetyl learning and thus integrate the aversive food context with the diacetyl odor, FLP-34 is released from serotonergic neurons and signals through its evolutionarily conserved NPY/NPF GPCR, NPR-11, in downstream AIA interneurons. NPR-11 activation in the AIA integration center results in avoidance of a previously attractive stimulus. This study opens perspectives for a deeper understanding of stress conditions in which aversive learning results in excessive avoidance.

The onset of sexual maturity involves dramatic changes in physiology and gene expression in many animals. These include abundant yolk protein production in egg-laying species, an energetically costly process under extensive transcriptional control. Here, we used the model organism Caenorhabditis elegans to provide evidence for the spatiotemporally defined interaction of two evolutionarily conserved transcription factors, CEH-60/PBX and UNC-62/MEIS, acting as a gateway to yolk protein production. Via proteomics, bimolecular fluorescence complementation (BiFC), and biochemical and functional readouts, we show that this interaction occurs in the intestine of animals at the onset of sexual maturity and suffices to support the reproductive program. Our electron micrographs and functional assays provide evidence that intestinal PBX/MEIS cooperation drives another process that depends on lipid mobilization: the formation of an impermeable epicuticle. Without this lipid-rich protective layer, mutant animals are hypersensitive to exogenous oxidative stress and are poor partners for mating. Dedicated communication between the hypodermis and intestine in C. elegans likely supports these physiological outcomes, and we propose a fundamental role for the conserved PBX/MEIS interaction in multicellular signaling networks that rely on lipid homeostasis.

Base excision repair causes age-dependent accumulation of single-stranded DNA breaks that contribute to Parkinson disease pathology Graphical abstract Highlights d Incomplete base excision repair is a source of genomic stress during aging d The NTH-1 DNA glycosylase is a key mediator of agedependent genomic instability d Compromised NTH-1 activity promotes neuroprotection in PD nematodes d NTH-1 deficiency triggers LMD-3/JNK-1/SKN-1-dependent mitohormetic response

Under non-stressed conditions, the redox status of the different subcellular compartments is tightly controlled . Hence, the cytoplasm has a reducing environment that favours cysteine protein residues in their dithiol form while the endoplasmic reticulum environment is oxidizing to facilitate the formation of disulfide bonds for protein folding . This situation is reversed in the presence of aggregation-prone proteins, as both com partments undergo a dramatic shift in their respective redox status, with the cytoplasm becoming more oxidized and the endoplasmic reticulum more reducing [1]. However, whether changes in the cellular redox status affect protein aggregation has not yet been addressed .We approached this hypothesis by using a C. elegans mutant strain lacking the gsr-1 gene, encoding glutathione reductase, the enzyme responsible for recycling oxidized glutathione (GSSG) and thus maintenance of glutathione redox homeostasis (2]. We found that gsr-1 deficiency enhances the deleterious phenotypes of worm di sea se models ca u sed by aggregating proteins like human b-amyloid peptide, a-synuclein or polyglutamine repeats containing proteins. lmportantly, gsr-1 dependent proteostatic disruption is also found in C. elegans strains expressing endogenous UNC-52 and LET-60 aggregate-prone metastable proteins. This deleterious effect is largely phenocopied by the GSH depleting agent diethyl ma leate [3].Protein aggregates can be disposed by autophagy and consistent with a role of GSR-1 in this process, gsr-1 mutants abolish nuclear translocation of the TFEB/HLH-30 transcription factor (a key mediator of autophagy induction) and strongly impair the degradation of the autophagy substrate p62/SQST -1 ::GFP. In agreement, genetic disruption of autophagy in gsr-1 mutants expressing aggregation prone proteins resulted in strong synthetic developmental phenotypes and in sorne cases lethality. Downregulation of glutathione reductase and GSH levels in both yeast and mammalian cell models also caused phenotypes associated to protein aggregation and impaired TFEB nuclear translocation [3]. Together, this study demonstrates a novel, evolutionarily conserved role of glutathione redox homeostasis in proteostasis maintenance through autophagy regulation . {1] Kirstein J, et al. (2015) Proteotoxtc stress and aqeinq triqqers the loss of redox homeostasis across ce/fular compartments. EMBO J. 34: 2334-49. {2] Mora-Larca JA et al. (20 16) Glutathione reductase qsr-1 is an essenttal gene required for Caenorhabditis eleqans earlv embryomc development. Free Radie Biol Med. 96:446-61 . {3] Guerrero-Gómez O, et al. (2019) Loss of qlutathtone redox homeostasis impairs proteostasis bv inhibitinq autophaqy-dependent protein deqradation. Ce// Oeath Oiffer. m press. 9

Thioredoxins are a class of evolutionarily conserved proteins that have been demonstrated to play a key role in many cellular processes involving redox reactions. We report here the genetic and biochemical characterization of Caenorhabditis elegans TRX-3, the first metazoan thioredoxin with an intestine-specific expression pattern. By using green fluorescent protein reporters we have found that TRX-3 is expressed in both the cytoplasm and the nucleus of intestinal cells, with a prominent localization at the apical membrane. Although intestinal function, reproductive capacity, longevity, and resistance of trx-3 loss-of-function mutants to many stresses are indistinguishable from those of wild-type animals, we have observed a slight reduction in size and a minor reduction in the defecation cycle timing of trx-3 mutants. Interestingly, trx-3 is induced upon infection by Photorhabdus luminescens and Candida albicans, and TRX-3 overexpression provides a modest protection against these pathogens. Together, our data indicate that TRX-3 function in the intestine is dispensable for C. elegans development but may be important to fight specific bacterial and fungal infections.

Interleukin 2 (IL-2) is a key homeostatic cytokine, with therapeutic applications in both immunogenic and tolerogenic immune modulation. Clinical use has been hampered by pleiotropic functionality and widespread receptor expression, with unexpected adverse events. Here, we developed a novel mouse strain to divert IL-2 production, allowing identification of contextual outcomes. Network analysis identified priority access for Tregs and a competitive fitness cost of IL-2 production among both Tregs and conventional CD4 T cells. CD8 T and NK cells, by contrast, exhibited a preference for autocrine IL-2 production. IL-2 sourced from dendritic cells amplified Tregs, whereas IL-2 produced by B cells induced two context-dependent circuits: dramatic expansion of CD8+ Tregs and ILC2 cells, the latter driving a downstream, IL-5–mediated, eosinophilic circuit. The source-specific effects demonstrate the contextual influence of IL-2 function and potentially explain adverse effects observed during clinical trials. Targeted IL-2 production therefore has the potential to amplify or quench particular circuits in the IL-2 network, based on clinical desirability.

28• C. elegans gsr-1 gene encodes cytoplasmic and mitochondria isoforms of glutathione reductase. 30• gsr-1 is essential for C. elegans embryonic development. 32• The lethality of gsr-1 mutants is due to a specific requirement of GSR-1 protein in the cytoplasm. 34• gsr-1 embryos have a progressive cell division delay and an aberrant distribution of interphasic 35 chromatin. 37• gsr-1 worms with maternally contributed GSR-1 are able to reach adulthood but display