Biology subjects

Mazzanti, M.

Publications and source records attributed to Mazzanti, M..

3 recordsLinked to original sources

bioRxiv2025

GAL-101 prevents amyloid beta-induced membrane depolarization in two different types of retinal cells

Glaucoma and age-related macular degeneration (AMD) are two of the major causes of progressive vision loss and ultimately blindness worldwide. Both retinopathies share several pathological features with Alzheimers disease (AD) such as: impairment of neuronal function, astrocytosis, and activation of immune-competent microglia and Muller cells. It also has been shown that these conditions are characterized by the presence of an elevated concentration of amyloid beta (A{beta}). Under pathological conditions, A{beta}1-42 tends to aggregate, forming toxic soluble oligomers, considered to be the most harmful amyloid species. One strategy adopted to prevent cell damage caused by these oligomers is to impair their aggregation. Here we studied GAL-101, a small molecule designed to modify the aggregation of A{beta}1-42. To assess the role of GAL-101 in the aggregation of A{beta}1-42, in vitro electrophysiological measurements on retinal ganglion cells (RGCs) and retinal pigment epithelial (RPE) cells were performed to determine the polarization of the resting membrane potential. Cells treated only with A{beta}1-42 oligomers showed a strong depolarization of the resting membrane potential, which is believed to be the main reason for retinal cells malfunctioning in neurodegenerative diseases of the eye. Pre-incubation with GAL-101 stabilized the cell resting potential to around -50mV during exposure to A{beta}1-42, in both RGCs and RPE cells. GAL-101 was able to prevent changes in resting membrane potential and thus would be expected to prevent impairment of retinal cell function. These results are supportive of evaluating GAL-101 as a potential treatment of A{beta}-associated retinopathies like glaucoma and dry AMD.

neuroscience↗

bioRxiv2022

Metformin antiproliferative activity is exclusively mediated by the membrane functional expression of the Chloride Intracellular Channel 1 in glioblastoma stem cells

Metformin is the first-line drug for type-2 diabetes. Retrospective analyses, based on diabetic patients clinical data, demonstrate that daily assumption of metformin reduces the incidence of several kinds of solid tumors. Even though it is widely agreed that metformin must be internalized to accomplish its pharmacological activity, direct evidence about metformin membrane permeability and/or the presence of a specific membrane receptor in cancer cells is still missing. Here, we show that the transmembrane form of Chloride Intracellular Channel 1 (tmCLIC1) works as a privileged metformin receptor in glioblastoma stem-like cells. We found that metformin impairs tmCLIC1 activity by a specific binding coordinated by arginine 29. Its mutation, preventing metformin to bind and block tmCLIC1, abolishes the biguanide inhibition of glioblastoma cell proliferation in 2D and 3D models and metformin dependent effect on mitochondrial respiration. In addition, we demonstrate the direct binding between the drug and its target, and by in vivo experiments on zebrafish embryos and mice orthotopically engrafted with glioblastoma cells and treated with metformin, we prove that metformin binding to tmCLIC1 is crucial for metformin antineoplastic effect. Considering tmCLIC1s contribution to glioblastoma progression, the present work provides the fundaments for future development of strategies aimed at improving metformin-tmCLIC1 interaction to further increase metformin therapeutic potential.

cancer biology↗

bioRxiv2021

Astrocytic extracellular vesicles modulate neuronal calcium homeostasis via transglutaminase-2

We have uncovered a novel role for astrocytes-derived extracellular vesicles (EVs) in controlling intraneuronal Ca2+ concentration ([Ca2+]i) and identified transglutaminase-2 (TG2) as a surface-cargo of astrocytes-derived EVs. Incubation of hippocampal neurons with primed astrocyte-derived EVs have led to an increase in [Ca2+]i, unlike EVs from TG2-knockout astrocytes. Exposure of neurons or brain slices to extracellular TG2 promoted a [Ca2+]i rise, which was reversible upon TG2 removal and was dependent on Ca2+ influx through the plasma membrane. Patch-clamp and calcium imaging recordings revealed TG2-dependent neuronal membrane depolarisation and activation of inward currents, due to the opening of L-type-VOCCs and to Na+/Ca2+ -exchanger (NCX) operation in the reverse mode, as indicated by VOCCs/NCX pharmacological inhibitors. A subunit of Na+/K+-ATPase was selected by comparative proteomics and identified as being functionally inhibited by extracellular TG2, implicating Na+/K+-ATPase inhibition in NCX reverse mode-switching leading to Ca2+ influx and higher basal [Ca2+]i. These data suggest that reactive astrocytes control intraneuronal [Ca2+]i through release of EVs with TG2 as responsible cargo, which could have a significant impact on synaptic activity in brain inflammation.

neuroscience↗