Biology subjects

Lasorsa, A.

Publications and source records attributed to Lasorsa, A..

4 recordsLinked to original sources

bioRxiv2025

Probing How Anti-Huntingtin Antibodies Bind The Fibrillar Fuzzy Coat Using Solid-State NMR

Antibodies are critical for the immune response and serve as important tools due to their ability to recognize specific amino acid sequences, or epitopes. Based on the latter, they are utilized as diagnostic tools in biological and biomedical research. Huntingtons disease (HD) is a neurodegenerative condition caused by CAG repeat expansions in the huntingtin (HTT) gene and characterized by amyloid-like protein deposits in patients. Multiple anti-HTT antibodies are used in HD research for their ability to recognize specific HTT inclusions in both post-mortem tissue and in laboratory conditions. Some of the antibodies are seen as detectors of distinct structural motifs. However, most knowledge of their binding mechanism stems from studies of soluble monomers or short fragments of the epitopes, rather than the aggregated, misfolded target protein. Here, we investigate how MW8 antibodies interact with HTT exon 1 (HTTex1) fibrils, using solid-state NMR, electron microscopy, and complementary techniques. Magic angle spinning NMR revealed localized impacts of the antibody on exposed parts of the HTTex1 fibrils: the flanking segments that form its fuzzy coat. Antibody binding affected the structure and dynamics of the fuzzy coat, but also modulated the propensity for forming supramolecular fibril clusters, which has important implications for (reducing) cytotoxicity.

biochemistry↗

bioRxiv2024

Resolving atomic-level dynamics and interactions of high-molecular weight hyaluronic acid in biomimetic ECM hydrogels by multidimensional solid-state NMR

High molecular weight (HMW) hyaluronic acid (HA) is a highly abundant natural polysaccharide and a fundamental component of the extracellular matrix (ECM). Its size and concentration regulate tissues macro- and microenvironments, and its upregulation is a hallmark feature of certain tumors. Yet, the conformational dynamics of HMW-HA and how it engages with components of the ECM microenvironment remain poorly understood on the molecular level. Probing the molecular structure and dynamics of HMW polysaccharides in a hydrated, physiological-like environment is crucial but also technically challenging. Here, we deploy advanced magic-angle-spinning (MAS) solid-state NMR (ssNMR) spectroscopy in combination with isotopic enrichment to enable an in-depth study of HMW-HA to address this challenge. This approach resolves multiple coexisting HA conformations and dynamics as a function of environmental conditions. By combining 13C-labeled HA with unlabeled ECM components, we detect by MAS NMR HA-specific changes in global and local conformational dynamics as a consequence of hydration and ECM interactions. These measurements reveal atom-specific variations in dynamics and structure of the N-acetylglucosamine (GlcNAc) moiety of HA. We discuss possible implications for interactions that stabilize the structure of HMW-HA and facilitate its recognition by HA-binding proteins. The described methods apply similarly to studies of the molecular structure and dynamics of HA in tumor contexts and in other biological tissues, as well as HMW-HA hydrogels and nanoparticles used for biomedical and/or pharmaceutical applications.

biophysics↗

bioRxiv2023

Production of isotopically enriched high molecular weight hyaluronic acid and characterization by solid-state NMR

Hyaluronic acid (HA) is a naturally occurring polysaccharide that is abundant in the extracellular matrix (ECM) of all vertebrate cells. HA-based hydrogels have attracted great interest for biomedical applications due to their high viscoelasticity and biocompatibility. In both ECM and hydrogel applications, high molecular weight (HMW)-HA can absorb a large amount of water to yield matrices with a high level of structural integrity. To understand the molecular underpinnings of structural and functional properties of HA-containing hydrogels, few techniques are available. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for such studies, e.g. 13C NMR measurements can reveal the structural and dynamical features of (HMW) HA. However, a major obstacle to 13C NMR is the low natural abundance of 13C, necessitating the generation of HMW-HA that is enriched with 13C isotopes. Here we present a convenient method to obtain 13C- and 15N-enriched HMW-HA in good yield from Streptococcus equi subsp. zooepidemicus. The labeled HMW-HA has been characterized by solution and magic angle spinning (MAS) solid-state NMR spectroscopy, as well as other methods. These results will open new ways to study the structure and dynamics of HMW-HA-based hydrogels, and interactions of HMW-HA with proteins and other ECM components, using advanced NMR techniques.

biophysics↗

bioRxiv2018

BIN1 recovers tauopathy-induced long-term memory deficits in mice and interacts with Tau through Thr348 phosphorylation

The bridging integrator 1 gene (BIN1) is a major genetic risk factor for Alzheimers disease (AD). In this report, we investigated how BIN1-dependent pathophysiological processes might be associated with Tau. We first generated a cohort of control and transgenic mice either overexpressing human MAPT (TgMAPT) or both human MAPT and BIN1 (TgMAPT;TgBIN1), which we followed-up from 3 to 15 months. In TgMAPT;TgBIN1 mice short-term memory deficits appeared earlier than in TgMAPT mice; however - unlike TgMAPT mice - TgMAPT;TgBIN1 mice did not exhibit any long-term or spatial memory deficits for at least 15 months. After sacrifice of the cohort at 18 months, immunohistochemistry revealed that BIN1 overexpression prevents both Tau mislocalization and somatic inclusion in the hippocampus, where an increase in BIN1-Tau interaction was also observed. We then sought mechanisms controlling the BIN1-Tau interaction. We developed a high-content screening approach to characterize modulators of the BIN1-Tau interaction in an agnostic way (1,126 compounds targeting multiple pathways), and we identified - among others - an inhibitor of Calcineurin, a Ser/Thr phosphatase. We determined that Calcineurin dephosphorylates BIN1 on a Cyclin-dependent kinase phosphorylation site at T348, promoting the open conformation of the neuronal BIN1 isoform. Phosphorylation of this site increases the availability of the BIN1 SH3 domain for Tau interaction, as demonstrated by nuclear magnetic resonance experiments and in primary neurons. Finally, we observed that the levels of the neuronal BIN1 isoform were decreased in AD brains, whereas phospho-BIN1(T348):BIN1 ratio was increased, suggesting a compensatory mechanism. In conclusion, our data support the idea that BIN1 modulates the AD risk through an intricate regulation of its interaction with Tau. Alteration in BIN1 expression or activity may disrupt this regulatory balance with Tau and have direct effects on learning and memory.

neuroscience↗