Biology subjects

Bonhoure, A.

Publications and source records attributed to Bonhoure, A..

3 recordsLinked to original sources

bioRxiv2025

Structural analysis of HERC2/UBE3A and HERC2/DOCK10 complexes provides new insights into the molecular basis of Angelman, Angelman-like and Dup15q Syndromes

UBE3A and HERC2 are two mutually interacting HECT E3 Ubiquitin ligases whose genes are altered in 15q11.2-13.1 Duplication (Dup15q) Syndrome, Angelman Syndrome (AS) and other phenotypically-related mental retardation syndromes. Using quantitative binding assays, X-ray crystallography and sequence conservation analysis, we show that the HERC2/UBE3A complex occurs in probably most animals with a central nervous system, via a conserved interface involving the RLD2 domain of HERC2 and a "DxDKDxD" motif of UBE3A. We found that HERC2 also recognizes and binds to similar DxDKDxD motifs within a handful of other proteins relevant to brain development (DOCK10, PCM1, USP35, BAZ2B, ARID4A, ARIP4, RERE and MYT1). We further investigated the interaction of HERC2 with DOCK10, a RAC1- and CDC42-GEF protein that regulates dendritic spine morphogenesis in hippocampal neurons. Both disruption of the HERC2-binding motif in DOCK10 and knockdown of HERC2 affected the GEF activity of DOCK10. We also show that the DOCK10-induced dendritic spine formation is dependent on its ability to bind HERC2. Structural modeling of full-length DOCK10, free or bound to either RLD2, CDC42 or RAC1 indicates that the GEF activation of full-length DOCK10 requires a conformational change that is stimulated by binding to HERC2. Based on our data, we propose that under pathological conditions, in developing brains with an abnormal dosage of either HERC2 or its dominant partner UBE3A, increased or decreased amounts of HERC2/DOCK10 complexes could lead to altered GTPase activation. This in turn could affect dendritic spine formation and neurodevelopment.

biochemistry↗

bioRxiv2024

Intracellular Pseudomonas aeruginosa persist and evade antibiotic treatment in a wound infection model

Persistent bacterial infections evade host immunity and resist antibiotic treatments through various mechanisms that are difficult to evaluate in a living host. Pseudomonas aeruginosa is a main cause of chronic infections in patients with cystic fibrosis (CF) and wounds. Here, by immersing wounded zebrafish embryos in a suspension of P. aeruginosa isolates from CF patients, we established a model of persistent infection that mimics a murine chronic skin infection model. Live and electron microscopy revealed persisting aggregated P. aeruginosa inside zebrafish cells, including macrophages, at unprecedented resolution. Persistent P. aeruginosa exhibited adaptive resistance to several antibiotics, host cell permeable drugs being the most efficient. Moreover, persistent bacteria could be partly re-sensitized to antibiotics upon addition of anti-biofilm molecules that dispersed the bacterial aggregates in vivo. Collectively, this study demonstrates that an intracellular location protects P. aeruginosa in vivo from host innate immunity and antibiotics, and provides new insights into efficient treatments against chronic infections.

microbiology↗

bioRxiv2020

Exosomal melanotransferrin as a potential biomarker for metastatic melanoma

Cutaneous melanoma is the most lethal type of skin cancer. Early detection is crucial to improve the outcome of melanoma patients. The identification of noninvasive prognostic biomarkers for the follow-up of melanoma patients is still in demand for clinical use. We show here that exosomal melanotransferrin (MTf) fulfils the biomarker characteristics required to meet this demand. MTf is typically overexpressed in melanoma cells compared to other cell types - including cancer cells - and is efficiently sorted and secreted with nanovesicles, or so-called exosomes, due to its membrane-anchoring by a glycosylphosphatidylinositol. MTf is exposed on the surface of exosomes and is accessible for antibody recognition. An ELISA was set-up to quantify MTf after immobilization of nanovesicles through the exosomal constituent tetraspanins CD63. MTf was detected using low number of exosomes purified from melanoma cell line cultures, and MTf detection was abolished by phosphatidylinositol-specific phospholipase C (PI-PLC) treatment. This exosomal MTf ELISA was able to discriminate an equal number of assayed exosomes purified from two different melanoma cell lines (A-375 vs SK-MEL-28). Moreover, plasma samples from patients with melanoma and noncancer disease were assayed using this ELISA and exosomal MTf was validated as a potential melanoma biomarker.

cell biology↗