Biology subjects

Esposito, V.

Publications and source records attributed to Esposito, V..

3 recordsLinked to original sources

bioRxiv2025

Apurinic/apyrimidinic endodeoxyribonuclease 1 contributes to the repair of damaged intercalated-motif of telomeric sequences

Apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) is a key enzyme in the Base Excision Repair pathway, responsible for processing abasic (AP-) sites. Recent studies revealed that APE1 participates in repairing DNA secondary structures as G-quadruplexes (G4). Telomeres, stabilized by shelterin proteins, are rich in G4, where APE1 binds and repairs AP-sites to maintain their integrity. The complementary cytosine-rich strand forms another structure, the i-motif (iM), essential for telomere maintenance, though its repair mechanism remains unclear. Herein we investigate APE1 binding and processing capabilities toward native and damaged telomeric iM, bearing AP-sites in different positions. Using biochemical and biophysical assays, we found that APE1 binds the telomeric iM-sequence and that its cleavage efficiency depends on AP-site position within iM. Proximity Ligation Assay analysis, in HeLa and U2OS cells, highlighted a novel interaction between APE1 and PCBP1, a well-known iM-folding modulator. PCBP1 binds iM with higher affinity than APE1 and inhibits its cleavage activity on damaged iM. Immunofluorescence and Telomere Restriction Fragment analyses showed that depletion of APE1 or PCBP1 impairs their interaction with the shelterin components, affecting telomere length. These results connect APE1 canonical DNA repair activity with the maintenance of non-canonical DNA secondary structures in telomeres, through its interaction with PCBP1. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/694817v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1962c63org.highwire.dtl.DTLVardef@3c3f60org.highwire.dtl.DTLVardef@164d78borg.highwire.dtl.DTLVardef@1831aae_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2022

Characterization of undocumented CO2 hydrothermal vents in the Mediterranean Sea: implications for ocean acidification studies

A previously undocumented shallow water hydrothermal field from Sicily (Southern Tyrrhenian Sea, Italy), is here described based on a multidisciplinary investigation. The field, covering an area of nearly 8000 m2 and ranging in depth from surface to -5 m, was explored in June 2021, to characterise the main physico-chemical features of the water column, describe bottom topography and features, and identify the main megabenthic and nektonic species. Twenty sites were investigated to characterize the carbonate system. Values of pH ranged between 7.84 and 8.04, {Omega}Ca between 3.68 and 5.24 and {Omega}Ar from 2.41 to 3.44. Geochemical analyses of hydrothermal fluids gases revealed a dominance of CO2 (98.1%) along with minor amounts of oxygen and reactive gases. Helium isotope ratios (R/Ra =2.51) and {delta}13CCO2 (3) support an inorganic origin of hydrothermal degassing of CO2 and the ascent of heat and deep-seated magmatic fluids to the surface. Visual census of fishes and megabenthos (mainly sessile organisms) allowed identification of 62 species, of which four are protected by the SPA/BIO Protocol and two by the International Union for Conservation of Nature. The macroalgae Halopteris scoparia and Jania rubens and the sponge Sarcotragus sp. were the dominant taxa in the area, while among fishes Coris julis and Chromis chromis were predominant. The preliminary description of this venting field indicates this site as an area of considerable interest and suitable for future experimental studies on ocean acidification.

ecology↗

bioRxiv2022

Adipocyte differentiation of 3T3-L1 cells under TAF, TDF and INSTIs selective challenge: an in vitro model.

Integrase strand transfer inhibitors (INSTI) are a recently available class of antiretroviral therapy (ART) medications with a good tolerability profile and a high genetic barrier to HIV drug resistance. However, several studies report more significant weight gain among persons receiving INSTI-based ART regimens for initial therapy compared to protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NNRTI)-based regimens. In our experimental setting, we used the in vitro model of adipogenesis of 3T3-L1 cells to investigate the effects of the NRTIs tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF), alone or in combination with four integrase strand transfer inhibitors: raltegravir (RAL), elvitegravir (ELV), dolutegravir (DTG) and bictegravir (BIC) on adipose differentiation. In addition, protein expression levels of PPAR{gamma} and C/EBP, and the intracellular lipid accumulation by Red Oil staining, were used to monitor adipocyte differentiation. Compared to control, RAL, ELV, DTG, and BIC were all able to increase adipogenesis, being in this, RAL and ELV more efficient. On the other hand, TAF and TDF inhibited adipogenesis. Moreover, when used in combination with the other INSTI molecules, TAF and TDF were able to reduce the adipogenic effects of all four drugs. This ability was more evident when TAF was used in combination with DTG and BIC. All these data suggest that TAF and TDF have an inhibitory effect on adipogenesis in vitro and that they could also effectively counteract the increased adipogenesis caused by the treatment with INSTIs. Finally, to evaluate if the 3T3-L1 cell could express fibroblast-like features following INSTIs treatment, we evaluated the immunohistochemical expression of ER-TR7, a well-known fibroblastic marker. This last assay showed that treatment with INSTIs increased the expression of ER-TR7 compared to control and to cells treated with TAF o TDF. In conclusion, our experimental data support the evidence that in vitro challenge of 3T3-L1 cells with INSTIs is able to increase adipocytic differentiation and to drive a number of these cells toward the expression of fibroblastic features, with a different degree according to the various drugs used, while TAF and TDF have an antagonistic role on this phenomenon.

pharmacology and toxicology↗