Biology subjects

Serafino, A.

Publications and source records attributed to Serafino, A..

4 recordsLinked to original sources

bioRxiv2025

Reverse transcriptase inhibitors induce autophagy in a LINE-1 ORF1p-dependent manner

Human Long Interspersed Nuclear Element-1 (LINE-1) retrotransposons propagate throughout the genome via reverse-transcribed RNA intermediates. LINE-1 expression is pervasive in cancer. Functional LINE-1s encode two proteins: ORF1p, an RNA-binding protein, and ORF2p, harboring reverse transcriptase and endonuclease activities. Reverse transcriptase inhibitors, including non-nucleoside (NNRTI) and nucleoside (NRTI) inhibitors, inhibit cancer cell proliferation and antagonize cancer progression. We previously found that two NNRTIs induced DNA damage, nuclear lamin rupture, micronuclei formation, and autophagy in prostate cancer cells. We now find that two different RTIs up-regulate LINE-1 mRNA expression and ORF1p abundance in nuclei, triggering ORF1p interactions with lamin B1 and with DNA damage factors. ORF1p accumulates within micronuclei with damaged DNA and with the autophagy receptor p62. We further demonstrate that inhibiting autophagy, or decreasing ORF1p levels, prevent DNA damage and preserve lamin B1 integrity, uncoverig a role of LINE-1-ORF1p in the autophagy response of cancer cells, independent on retrotranscription events.

cell biology↗

bioRxiv2024

Cytoplasmic accumulation of a splice variant of hnRNP A2/B1 contributes to FUS-associated toxicity in a mouse model of ALS

Genetic and experimental findings point to a crucial role of RNA dysfunction in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS). Evidence suggests that mutations in RBPs such as FUS, a gene associated with ALS, affect the regulation of alternative splicing. We have previously shown that the overexpression of wild-type FUS in mice, a condition that induces ALS-like phenotypes, impacts the splicing of hnRNP A2/B1, a protein with key roles in RNA metabolism, suggesting that a pathological connection between FUS and hnRNP A2/B1 might promote FUS-associated toxicity. Here we report that the expression and distribution of different hnRNP A2/B1 splice variants are modified in the affected tissues of mice overexpressing wild-type FUS. Notably, degenerating motor neurons are characterized by the cytoplasmic accumulation of splice variants of hnRNP A2/B1 lacking exon 9 (hnRNP A2b/B1b). In vitro studies show that exon 9 skipping affects the nucleocytoplasmic distribution of hnRNP A2/B1, promoting its localization into stress granules (SGs), and demonstrate that cytoplasmic localization is the primary driver of hnRNP A2b recruitment into SGs and cell toxicity. Finally, boosting exon 9 skipping using splicing switching oligonucleotides exacerbates disease phenotypes in wild-type FUS mice. Altogether, these findings reveal that alterations of the nucleocytoplasmic distribution of hnRNP A2/B1, driven by FUS-induced splicing changes, likely contribute to motor neuron degeneration in ALS.

neuroscience↗

bioRxiv2024

The RNA from Pseudomonas aeruginosa impairs neutrophil responses favoring bacterial survival

Epithelial and endothelial cells are essential in the modulation of innate immune responses in the lung, including the arrival of neutrophils (PMN), which are crucial cells for the antibacterial host defense. These cells are exposed to prokaryotic RNA (pRNA) during bacterial infections and pRNA has been shown to promote or attenuate the inflammatory response on different immune cells. Pseudomonas aeruginosa (PAE) can cause severe pneumonia and has several immune-evading mechanisms. The aim of this study was to determine the effects of the RNA from PAE (RNAPAE) on lung epithelial, endothelial cells and PMN, and its impact on bacterial elimination. For this purpose, we purified total RNAPAE, and used it as a stimulus to evaluate different functions on Calu-6, HMEC-1 and isolated human PMN. We found that RNAPAE neither induced a pro-inflammatory response on Calu-6 or HMEC-1, as measured by ICAM-1 surface expression, or IL-6 and IL-8 secretion. Also, RNAPAE failed to activate PMN, as measured by forward-scatter (FSC) increase, CD11b surface expression, chemotaxis and IL-8 secretion. Pre-stimulation with RNAPAE diminished CD11b surface expression, chemotaxis and microbicidal activity when PMN were challenged with live bacteria. Moreover, we found that phagocytosis was affected in the presence of RNAPAE. Fragments of short RNA (<200 bp) were responsible for the PMN microbicidal attenuation during bacterial elimination. In conclusion, our results indicated that short fragments of RNAPAE diminished the immune response on PMN even in the presence of live bacteria. AUTHOR SUMMARYPseudomonas aeruginosa (PAE) pneumonia constitutes a major problem for human health. Therapies are frequently inefficient due to immune evasion mechanisms of PAE. Therefore, it is imperative to understand the relationship between PAE (or its components) with the immune system to improve therapeutic strategies. Since some bacterial RNA are immunosuppressive, our hypothesis was that the RNA from PAE (RNAPAE) might negatively modulate the immune response in a lung infection. We investigated the effects of the RNAPAE on lung epithelial, and microvascular endothelial cells, central cells that respond to PAE early during infection, and on neutrophils (PMN), the first immune cell that arrives at the site of infection. We found that RNAPAE failed to induce any response on pulmonary epithelium, endothelium, or PMN. Moreover, RNAPAE-treated PMN showed reduced migration, activation, and bactericidal response against live bacteria. Exploring deeper into this phenomenon, we found that increased bacterial survival was due to a lower phagocytic capacity of RNAPAE-treated PMN. Our results indicate that RNAPAE may act as another evasion strategy to favor PAEs survival in a pulmonary infection. Understanding the mechanisms by which PAE reduces the response of cells that participate in pulmonary immunity is crucial for planning interventions that may benefit infected patients.

immunology↗

bioRxiv2023

Cross-transmission of resistant gastrointestinal nematodes between wildlife and transhumant sheep

Wild and domestic ungulates can be infected with the same species of gastrointestinal parasitic nematodes. These parasites have free-living stages in the environment that contribute to the ease of transmission among different host species. In addition, gastrointestinal nematodes have developed resistance to anthelmintics which is now considered a major problem for the livestock sector. In a context where wild and domestic ungulates share the same pastures, the maintenance and circulation of resistant gastrointestinal nematodes between species have rarely been explored. In the European Alps, domestic sheep are driven to high-altitude summer pastures and live in sympatry with wild ungulates for several months each year. In this study, we investigated the nemabiome of domestic sheep and Alpine ibex, Capra ibex, in three different areas of the French Alps to evaluate parasite circulation between the two host species. The Alpine ibex is a protected mountain ungulate that is phylogenetically related to sheep and hosts nematode species common to sheep. Using internal transcribed spacer 2 (ITS-2) nemabiome metabarcoding, we found sheep and ibex share similar gastrointestinal nematodes, except for a few species such as Marshallagia marshalli and Trichostrongylus axei. This suggests that the long-term co-occurrence of sheep and ibex on mountain pastures has promoted the exchange of gastrointestinal nematodes between the two hosts. Based on the sequencing of the isotype 1 of the beta tubulin gene, associated with benzimidazole resistance, we found resistant nematodes in all sheep flocks and in all ibex populations. Our results demonstrated that ibex can host and shed resistant strains before transhumant sheep arrive on pastures, and thus could act as a refuge or even contribute to maintaining resistant gastrointestinal nematodes. The relative role of ibex in the maintenance and circulation of resistant strains in sheep remain to be determined.

ecology↗