Biology subjects

Chiesa, C.

Publications and source records attributed to Chiesa, C..

3 recordsLinked to original sources

bioRxiv2026

Nitazoxanide activates BMP9-ALK1-SMAD signaling cascade and improves HHT vascular pathology

ObjectiveHereditary hemorrhagic telangiectasia (HHT) is a vascular genetic disorder caused by endothelial cell dysfunction and characterized by telangiectasias and arteriovenous malformations (AVMs). HHT results primarily from loss-of-function mutations affecting components of the BMP9-ALK1-ENG-SMAD signaling cascade, a pathway essential for endothelial quiescence and vascular homeostasis, and currently lacks a cure. Here, we investigated whether nitazoxanide, an orally bioavailable drug with extensive clinical use, can modulate endothelial signaling relevant to HHT. Approach and ResultsNitazoxanide treatment activated SMAD1/5/8 signaling and increased expression of the downstream target ID1 in endothelial cells, while concurrently inhibiting mTOR signaling, indicating a dual modulatory effect on pathways implicated in HHT pathogenesis. In vivo, nitazoxanide activated SMAD signaling in BMP9/10-immunoblocked mice and significantly reduced AVM formation and hypervascularization. Importantly, nitazoxanide restored SMAD1/5/8 activation and ID1 expression in patient-derived blood outgrowth endothelial cells harboring loss-of-function mutations in ALK1 or SMAD4, which exhibit impaired BMP signaling. ConclusionThese findings identify nitazoxanide as a pharmacological modulator capable of activating BMP-SMAD signaling while restraining mTOR activity, thereby overcoming key signaling defects in HHT endothelial cells. Collectively, our results highlight nitazoxanide as a promising therapeutic candidate to target endothelial dysfunction in HHT.

cell biology↗

bioRxiv2025

Discovery and Characterisation of a Plant GH1 beta-Glucosidase Exhibiting Hydrolytic Activity on an N-Linked Glucopyranoside

{beta}-Glucosidases (Bgls) catalyse the hydrolysis of the glycosidic bond of {beta}-D-glycosides. Ubiquitous in nature, they play vital biological roles across diverse organisms, and their versatility has made them valuable for industrial applications. Bgls are commonly known to hydrolyse O- and S-linked glycopyranosides, but their activity on N-linked glycopyranosides has yet to be demonstrated. In a previous study, we discovered and biocatalytically produced a novel N-glucopyranoside, methyl anthranilate-N-{beta}-D-glucopyranoside (MANT-N-glucose). Building on this, we sought to develop a biocatalytic method for the degradation of MANT-N-glucose into its two main components, methyl anthranilate and glucose. Through screening of a eukaryotic Bgl library, we identified ZmGlu1 as an enzyme capable of hydrolysing MANT-N-glucose. This reaction displayed substantially reduced catalytic efficiency (0.31 min-1 mM-1) relative to ZmGlu1s activity with its native substrate and other O-glucopyranosides. Structural modelling of enzyme-substrate complexes revealed key interactions likely contributing to the reduced activity. These findings provide a foundation for future investigations into N-glycopyranoside Bgl reactivity and highlight the broader potential of Bgls in biocatalytic applications. ImportanceIn this study, we uncover a previously unknown function within the widely used enzyme, {beta}-glucosidases (Bgls). These enzymes catalyse the hydrolysis of O- and S-linked glycopyranosides, yet their ability to act on N-linked glycopyranosides has remained unrecognised until now. Using both human gut bacteria and a library of eukaryotic Bgls, we identified and characterised an enzyme capable of hydrolysing an N-linked substrate, methyl anthranilate-N-{beta}-D-glucopyranoside. This finding expands the recognised activity range of Bgls and highlights their broader industrial relevance. In addition, this finding opens avenues for further investigation into Bgls substrate selectivity, as well as enzyme engineering aimed at enhancing activity toward N-linked glycopyranosides and elucidating the underlying structure-function.

biochemistry↗

bioRxiv2025

Enzymatic Glycosylation of Anthranilates for Enhanced Functionality

Anthranilate (ANT) is a precursor for the synthesis of valuable compounds, including its alkyl esters (AEANTs), such as methyl anthranilate (MANT). These derivatives are industrial petrochemical products used as flavouring agents and bird repellents. Due to the mandatory green transition, their biological industrial production must be considered. However, their antimicrobial activity and physicochemical properties inhibit efficient microbial production and challenge their practical use. To overcome this, we explored enzymatic glycosylation using UDP-dependent glycosyltransferases (UGTs). Screening identified three UGTs with activity on a selected AEANT panel, with UGT72B68 from Solanum lycopersicum showing the highest efficiency (840 s-1 M-1) for MANT. Rational engineering produced a mutant (F145M) with improved activity for bulkier AEANTs. We scaled up enzymatic synthesis, producing 9.3 g of MANT-N-glucose (>99% purity, 74% yield). With this in hand, we observed that MANT-N-glucose has a significantly lower impact on the growth of E. coli and P. putida, supporting microbial production. Furthermore, we found that MANT-N-glucose completely inhibited sunflower seed consumption, compared to a 70% reduction observed in a previous study using MANT, when tested on captured red-winged blackbirds. Finally, a preliminary life-cycle assessment demonstrated that microbially produced MANT-N-glucose is a viable alternative to chemically synthesised MANT as a bird repellent.

biochemistry↗