Biology subjects

Sousa, M. J.

Publications and source records attributed to Sousa, M. J..

4 recordsLinked to original sources

bioRxiv2024

Circulating microRNAs as biomarkers of chronic kidney disease and its association with renal and cardiovascular outcomes in non-dialysis patients

Chronic kidney disease (CKD) affects over 10% of the population worldwide and entails a significant risk for cardiovascular disease (CVD), leading to a 500-fold increase in cardiovascular mortality in advanced stages. Still, the pathophysiological mechanisms underlying kidney-heart intercommunication remain largely unknown. In recent years, microRNAs (miRNAs) emerged as important key regulators of gene expression that may serve as biomarkers for several diseases, however, their role in kidney-heart crosstalk in CKD remains underexplored. In this study, we evaluated the expression of a miRNA panel in plasma samples from non-dialysis CKD patients and explored their association with main comorbidities and significant outcomes in a 5-year follow-up. Results show that miR-30c-5p and miR-132-3p were downregulated in CKD patients presenting a significant power to discriminate the disease state. Importantly, only miR-30c-5p was downregulated in early glomerular filtration rate (GFR) categories, being able to discriminate these CKD patients from non-diseased individuals. Concerning cardiovascular outcomes, miR-199a-5p was found to be associated with an increased frequency of CVD. When analyzing the major disease outcomes in a 5-year time, miR-199a-5p upregulation at baseline was associated with increased mortality, while miR-324-3p was downregulated in patients who progressed to more advanced stages of the disease. These findings highlight the involvement of novel circulating miRNAs in CKD onset and progression, and identify, for the first time, the enrollment of miR-199a-5p in kidney-heart pathophysiological crosstalk, paving the way for the establishment of new biomarkers and therapeutic targets for CKD and its outcomes.

molecular biology↗

bioRxiv2024

The widely used cymoxanil fungicide impairs respiration in Saccharomyces cerevisiae via cytochrome c oxidase inhibition

Cymoxanil (CYM) is a synthetic acetamide fungicide that has been widely used to combat downy mildew diseases in grapevine cultures and late blight diseases in tomato and potato caused by the oomycetes Plasmopara viticola and Phytophthora infestans, respectively. Despite its extensive application, the biochemical mode of action of CYM remains elusive. Previous reports indicate that CYM affects growth, DNA and RNA synthesis in Phytophthora and inhibits cell growth, biomass production and respiration rate in the well-characterized fungal model Saccharomyces cerevisiae. We therefore used this model to further characterize the effect of CYM on mitochondria. We found that CYM inhibits oxygen consumption in whole cells after 3 h of exposure, which persists over time. Using isolated mitochondria, we demonstrated that CYM specifically inhibits cytochrome c oxidase (CcO) activity during oxidative phosphorylation. Based on molecular docking algorithms, we propose that CYM acts by blocking the interaction of cytochrome c (cyt c) with CcO, hampering electron transfer and inhibiting CcO catalytic activity. Although other targets cannot be excluded, our data offer valuable insights into the mode of action of CYM that can be instrumental to drive informed management of the use of this fungicide.

biochemistry↗

bioRxiv2024

The antifungal activity of cymoxanil is associated with proton pump inhibition and disruption of plasma membrane potential

Worldwide use of agrochemicals, particularly pesticides, is necessary to increase agricultural production to feed the ever-growing population. However, despite widespread use, the biochemical mode of action of many agrochemicals and their potential deleterious effects on the environment are poorly characterized. Cymoxanil (CYM) is a fungicide used to combat downy mildew diseases in grapevine cultures and late blight diseases in tomato and potato cultures caused by the oomycetes Plasmopara viticola and Phytophthora infestans, respectively. Previous reports indicate that CYM affects growth, DNA and RNA synthesis in Phytophthora and inhibits cell growth, biomass production and respiration rate in the well-characterized fungal model Saccharomyces cerevisiae. We therefore used this model to further dissect mechanisms underlying the toxicological effects of CYM. We found that CYM induced genome-wide alterations, particularly in membrane transporter systems. These alterations were associated with perturbations in lipid-raft organization and inhibition of Pma1p, leading to a decrease in plasma membrane potential and intracellular acidification. Altogether, these findings identify the plasma membrane as one of the targets of CYM and proposes a mode of action underlying its antifungal activity.

cell biology↗

bioRxiv2023

Shifting KRAS hotspot mutations inhibition paradigm in colorectal cancer

KRAS hotspot mutations are difficult to target, highlighting the need of developing new specific target drugs for cancers driven by these mutations, like colorectal cancer (CRC). Here, we discover a new ruthenium compound, PMC79, that inhibits specifically mutated KRAS and the downstream signaling ERK and AKT proteins both "in vitro" and "in vivo". We demonstrated that PMC79 inhibits KRAS mutated kinase activity and is selective for KRAS mutations not affecting the KRAS wild-type protein. KRAS inhibition is not dependent on actin polymerization or on proteasome. Molecular docking analysis suggests that this effect might result from protein dynamics associated with the mutations. We demonstrated that low doses of PMC79 potentiate 5-fluorouracil anticancer effect. "In vivo" PMC79 "proof of concept" showed that it reduces tumor growth in the CAM-xenograft model and induces necrosis of the tumor in the xenograft mice model. PMC79 is a promising new "magic bullet" for CRCs harboring mutated KRAS.

pharmacology and toxicology↗