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PAPERS PUBLISHED IN INTERNATIONAL SCIENTIFIC JOURNALS DURING 2020

Borbolis F, Rallis J, Kanatouris G, Kokla N, Karamalegkos A, Vasileiou C, Vakaloglou KM, Diallinas G, Stravopodis DJ, Zervas CG, Syntichaki P. 2020 mRNA decapping is an evolutionarily conserved modulator of neuroendocrine signaling that controls development and ageing. Elife. 2020 May 5;9:e53757. doi: 10.7554/eLife.53757. PMID: 32366357; PMCID: PMC7200159
 
Abstract: Eukaryotic 5'-3' mRNA decay plays important roles during development and in response to stress, regulating gene expression post-transcriptionally. In Caenorhabditis elegans, deficiency of DCAP-1/DCP1, the essential co-factor of the major cytoplasmic mRNA decapping enzyme, impacts normal development, stress survival and ageing. Here, we show that overexpression of dcap-1 in neurons of worms is sufficient to increase lifespan through the function of the insulin/IGF-like signaling and its effector DAF-16/FOXO transcription factor. Neuronal DCAP-1 affects basal levels of INS-7, an ageing-related insulin-like peptide, which acts in the intestine to determine lifespan. Short-lived dcap-1 mutants exhibit a neurosecretion-dependent upregulation of intestinal ins-7 transcription, and diminished nuclear localization of DAF-16/FOXO. Moreover, neuronal overexpression of DCP1 in Drosophila melanogaster confers longevity in adults, while neuronal DCP1 deficiency shortens lifespan and affects wing morphogenesis, cell non-autonomously. Our genetic analysis in two model-organisms suggests a critical and conserved function of DCAP-1/DCP1 in developmental events and lifespan modulation.
 

Dimou S, Diallinas G. 2020 Life and Death of Fungal Transporters under the Challenge of Polarity. Int J Mol Sci. 2020 Jul 29;21(15):5376. doi: 10.3390/ijms21155376
 
Abstract: Eukaryotic plasma membrane (PM) transporters face critical challenges that are not widely present in prokaryotes. The two most important issues are proper subcellular traffic and targeting to the PM, and regulated endocytosis in response to physiological, developmental, or stress signals. Sorting of transporters from their site of synthesis, the endoplasmic reticulum (ER), to the PM has been long thought, but not formally shown, to occur via the conventional Golgi-dependent vesicular secretory pathway. Endocytosis of specific eukaryotic transporters has been studied more systematically and shown to involve ubiquitination, internalization, and sorting to early endosomes, followed by turnover in the multivesicular bodies (MVB)/lysosomes/vacuole system. In specific cases, internalized transporters have been shown to recycle back to the PM. However, the mechanisms of transporter forward trafficking and turnover have been overturned recently through systematic work in the model fungus Aspergillus nidulans. In this review, we present evidence that shows that transporter traffic to the PM takes place through Golgi bypass and transporter endocytosis operates via a mechanism that is distinct from that of recycling membrane cargoes essential for fungal growth. We discuss these findings in relation to adaptation to challenges imposed by cell polarity in fungi as well as in other eukaryotes and provide a rationale of why transporters and possibly other housekeeping membrane proteins 'avoid' routes of polar trafficking.
 

Dimou S, Martzoukou O, Dionysopoulou M, Bouris V, Amillis S, Diallinas G. 2020 Translocation of nutrient transporters to cell membrane via Golgi bypass in Aspergillus nidulans. EMBO Rep. 2020 Jul 3;21(7):e49929. doi: 10.15252/embr.201949929. Epub 2020 May 26. PMID: 32452614; PMCID: PMC7332984
 
Abstract: Nutrient transporters, being polytopic membrane proteins, are believed, but not formally shown, to traffic from their site of synthesis, the ER, to the plasma membrane through Golgi-dependent vesicular trafficking. Here, we develop a novel genetic system to investigate the trafficking of a neosynthesized model transporter, the well-studied UapA purine transporter of Aspergillus nidulans. We show that sorting of neosynthesized UapA to the plasma membrane (PM) bypasses the Golgi and does not necessitate key Rab GTPases, AP adaptors, microtubules or endosomes. UapA PM localization is found to be dependent on functional COPII vesicles, actin polymerization, clathrin heavy chain and the PM t-SNARE SsoA. Actin polymerization proved to primarily affect COPII vesicle formation, whereas the essential role of ClaH seems indirect and less clear. We provide evidence that other evolutionary and functionally distinct transporters of A. nidulans also follow the herein identified Golgi-independent trafficking route of UapA. Importantly, our findings suggest that specific membrane cargoes drive the formation of distinct COPII subpopulations that bypass the Golgi to be sorted non-polarly to the PM, and thus serving house-keeping cell functions.
 

Kalampokis IF, Erban A, Amillis S, Diallinas G, Kopka J, Aliferis KA. 2020 Untargeted metabolomics as a hypothesis-generation tool in plant protection product discovery: Highlighting the potential of trehalose and glycerol metabolism of fungal conidiospores as novel targets. Metabolomics. 2020 Jun 29;16(7):79. doi: 10.1007/s11306-020-01699-7. PMID: 32601735
 
Abstract: Introduction: The production of high quality and safe food represents a main priority for the agri-food sector in the effort to sustain the exponentially growing human population. Nonetheless, there are major challenges that require the discovery of new, alternative, and improved plant protection products (PPPs). Focusing on fungal plant pathogens, the dissection of mechanisms that are essential for their survival provides insights that could be exploited towards the achievement of the aforementioned aim. In this context, the germination of fungal spores, which are essential structures for their dispersal, survival, and pathogenesis, represents a target of high potential for PPPs. To the best of our knowledge, no PPPs that target the germination of fungal spores currently exist. - Objectives: Within this context, we have mined for changes in the metabolite profiles of the model fungus Aspergillus nidulans FGSC A4 conidiospores during germination, in an effort to discover key metabolites and reactions that could potentially become targets of PPPs - Methods: Untargeted GC/EI-TOF/MS metabolomics and multivariate analyses were employed to monitor time-resolved changes in the metabolomes of germinating A. nidulans conidiospores- Results: Analyses revealed that trehalose hydrolysis plays a pivotal role in conidiospore germination and highlighted the osmoregulating role of the sugar alcohols, glycerol, and mannitol - Conclusion: The ineffectiveness to introduce active ingredients that exhibit new mode(s)-of-action as fungicides, dictates the urge for the discovery of PPPs, which could be exploited to combat major plant protection issues. Based on the crucial role of trehalose hydrolysis in conidiospore dormancy breakage, and the subsequent involvement of glycerol in their germination, it is plausible to suggest their biosynthesis pathways as potential novel targets for the next-generation antifungal PPPs. Our study confirmed the applicability of untargeted metabolomics as a hypothesis-generation tool in PPPs' research and discovery.
 

Pouris J., Meletiou-Christou M.S., Chimona C. and Rhizopoulou S. 2020. Seasonal functional partitioning of carbohydrates and proline among plant parts of the sand daffodil. Agronomy, 10, 539, doi:10.3390/agronomy10040539
 
Abstract: The sand daffodil (Pancratium maritimum) is a perennial geophyte, widely distributed and grown in a wild stage along the Mediterranean seashores. The aboveground tissues of this geophyte are exposed to harsh, ambient conditions and its large inflorescences of remarkable beauty and fragrance expand during the drought season and carry particular ornamental worth. The ecophysiological principles underlining metabolic processes of this geophyte are poorly understood. The seasonal variation of soluble sugars, starch, and proline was investigated in individuals collected from patches of P. maritimum, therefore, monthly measurements were performed in bulbs, leaves, scapes, and petals during a year. It was found that (a) sugar content showed similar seasonal trends between bulbs and leaves, as well as between petals and scapes, (b) bulbs contained enhanced starch concentrations irrespective of season, (c) proline accumulation exhibited substantial seasonal fluctuations among the considered tissues and pronounced differences were detected between maxima in petals and leaves. A substantial increase in both sugar and proline content was evident in petals during the drought season. In leaves, the accumulation of proline and, to a lesser extent, sugars was negatively correlated to the precipitation of the Mediterranean study site. It seems likely that the astonishing flowering of P. maritimum is supported by large leaf and bulb reserves.