Biology subjects

Fierro, J.

Publications and source records attributed to Fierro, J..

3 recordsLinked to original sources

bioRxiv2025

Metabolic pathway competition sensitizes thioredoxin reductase-depleted Candida albicans to cell wall stress and antifungals

Candida albicans is the most common invasive human fungal pathogen. Each of the currently available 3 antifungal drug classes is limited by toxicities, drug interactions or inadequate penetration of critical tissues. We discovered a connection between C. albicans TOR and thioredoxin reductase, Trr1. Fungal and human thioredoxin reductases diverge fundamentally and are essential for repair of oxidatively damaged macromolecules, so they may be promising drug targets. We found that Trr1 is required for C. albicans growth at human body temperatures, hyphal growth regulation and management of oxidative and cell wall stress. Its depletion sensitizes C. albicans to AmphotericinB and to an echinocandin. TRR1-depleted cells have lower cell wall glucan content. Metabolomics experiments highlighted their perturbed pentose phosphate pathway (PPP). They have sharply elevated activity of glucose-6-phosphate dehydrogenase, the first, rate-limiting enzyme of the PPP. A key glycolytic, gluconeogenic and UDP-glucose biosynthetic enzyme each show decreased activity. UDP-glucose is the substrate of cell wall glucan-producing enzymes. We propose that Trr1-depleted cells accelerated glucose-6-phosphate flux into the PPP, driven by demand for NADPH reducing equivalents, diminishes glucose-6-phosphate availability for UDP-glucose production and hence for cell wall construction, weakening the wall. Strikingly dysregulated signaling pathways in Trr1-depleted cells contribute to their stress hypersensitivities.

microbiology↗

bioRxiv2021

Mapping the microbial diversity and natural resistome of north Antarctica soils

The rising of multiresistant bacterial pathogens is currently one of the most critical threats to global health, demanding a better understanding of the origin and spread of antibiotic resistance. In this regard, the resistome hosted by the microbiota from natural and remote environments remains poorly explored. Moreover, little is known about the availability of antimicrobial resistance genes (ARGs) from these environments to be disseminated through horizontal transfer, potentially mediating the rise of novel resistance factors among clinically relevant pathogens. In this context, the North Antarctica soils are attractive ecosystems to study due to the presence of a microbiota naturally adapted to thrive in harsh conditions, including potential factors to resist natural toxic substances. In this work, we evaluated the antibiotic resistance of bacteria isolated from soils collected in humanized and non-intervened areas of North Antarctica. We identified resistance to a wide array of antibiotics, with isolates harboring up to 10 simultaneous resistances, mainly native Pseudomonas. Genomic analysis revealed the presence of a wide array of genes encoding efflux pumps but the lack of genes explaining some of the resistance phenotypes, suggesting novel uncharacterized mechanisms. Also, using 16S rRNA amplicon and shotgun metagenome sequencing, we explored the microbial diversity in the sampled soils and evaluated the presence of ARGs and their host microbiota. High microbial diversity was found in all the sites, with Proteobacteria, Bacteroidota, Acidobacteriota, and Verrucomicrobiota being the most abundant Phyla, while Candidatus Udaeobacter, RB41, Polaromonas, and Ferruginibacter the most abundant genera. We identified hundreds of genes potentially conferring resistance to more than 15 drug classes, both by short reads analyses and ARG detection among assembled contigs and MAGs obtained combining short and long-read sequence data. Polaromonas, Pseudomonas, Streptomyces, Variovorax, Bhurkolderia, and Gemmatimonas were the main host taxa of the identified ARGs. Part of these ARGs was found inside predicted plasmids, including a putative OXA-like beta-lactamase from Polaromonas harboring the key conserved residues of this kind of enzyme and a conserved predicted protein structure. All this evidence indicates that microbial communities from North Antarctica soil have a highly diverse natural resistome, part of it located inside mobile genetic elements, which would act as a source of novel ARGs.

microbiology↗

bioRxiv2020

Targeted Next-Generation Sequencing Identifies Pathogenic Variants in Kidney Disease-Related Genes in Patients with Diabetic Kidney Disease

Diabetes is the most common cause of chronic kidney disease (CKD). For patients with diabetes and CKD, the underlying cause of their kidney disease is often assumed to be a consequence of their diabetes. Without histopathological confirmation, however, the underlying cause of their kidney disease is unclear. Recent studies have shown that next-generation sequencing (NGS) provides a promising avenue toward uncovering and establishing precise genetic diagnoses in various forms of kidney disease. Here, we set out to investigate the genetic basis of disease in non-diabetic kidney disease (NDKD) and diabetic kidney disease (DKD) patients by performing targeted NGS using a custom panel comprised of 345 kidney disease-related genes. Our analysis identified rare diagnostic variants that were consistent with the clinical diagnosis of 19% of the NDKD patients included in this study. Similarly, 22% of DKD patients were found to carry rare pathogenic/likely pathogenic variants in kidney disease-related genes included on our panel. Genetic variants suggestive of NDKD were detected in 3% of the diabetic patients included in this study. Our findings suggest that rare variants in kidney disease-related genes in the context of diabetic pathophysiology may play a role in the pathogenesis of kidney disease in patients with diabetes. Key MessagesO_LIWhat is already known about this subject? O_LIFor patients with diabetes and chronic kidney disease, the underlying cause of their kidney disease is often assumed to be a consequence of their diabetes; without histopathological confirmation, however, the underlying cause of their kidney disease is unclear. C_LIO_LINext-generation sequencing (NGS) provides a promising avenue toward uncovering and establishing precise genetic diagnoses in various forms of kidney disease. C_LI C_LIO_LIWhat are the new findings? O_LIUsing targeted NGS and a custom panel comprised of 345 kidney disease-related genes, we found that 22% of diabetic kidney disease patients were found to carry rare pathogenic/likely pathogenic variants in kidney disease-related genes included on our panel. C_LIO_LIGenetic variants suggestive of non-diabetic kidney disease were detected in 3% of the diabetic patients included in this study. C_LI C_LIO_LIHow might these results change the focus of research or clinical practice? O_LIOur findings suggest that rare variants in kidney disease-related genes in the context of diabetic pathophysiology may play a role in the pathogenesis of kidney disease in patients with diabetes. C_LIO_LIImportantly, improved understanding of the underlying disease process in diabetic kidney disease could have major implications in terms of patient care and monitoring as well as for research studies in this field. C_LI C_LI

genetics↗