Biology subjects

Chouaib, A. A.

Publications and source records attributed to Chouaib, A. A..

4 recordsLinked to original sources

bioRxiv2026

Interferon-γ promotes SMAP production by cytotoxic T lymphocytes in a thrombospondin 4 dependent manner

Cytotoxic T lymphocytes (CTLs) eliminate infected and cancerous cells by exocytosing cytotoxic granules, either as single-core granules (SCGs) releasing diffusible Granzyme B and Perforin, or as multi-core granules (MCGs) releasing these effectors as thrombospondin-1/4-encapsulated supramolecular attack particles (SMAPs). How CTLs differentially deploy these granule types remains unclear. We demonstrate that prolonged in vitro expansion and restimulation selectively enhance SMAP release, correlating with increased MCG maturation and thrombospondin-4 expression. Using high-resolution imaging, we identify fusion-competent MCG intermediates lacking SMAPs but releasing granzyme B diffusively. Mechanistically, interferon-{gamma} upregulates thrombospondin-4, driving MCG maturation and SMAP biogenesis, enhancing late-phase CTL killing efficiency against resistant targets. Consistent with this, THBS1 and THBS4 transcript levels appear elevated in melanoma-infiltrating CTLs compared with those during acute adenovirus infection. These findings define a stimulus-dependent, interferon-{gamma}-driven pathway tailoring CTL responses to chronic pathology and highlight opportunities for SMAP-targeted immunotherapies.

immunology↗

bioRxiv2025

Glutamatergic synaptic resilience to overexpressed human alpha-synuclein

Alpha synuclein (aSyn) is an abundant protein that, in the brain, is concentrated in neuronal presynaptic boutons and associates with synaptic vesicles. aSyn is strongly linked with Parkinsons disease (PD) due to its accumulation in pathognomonic inclusions in neuronal cells, including in glutamatergic neurons. While increased expression of wild-type (WT) aSyn due to multiplications of the SNCA gene, or the expression of mutant forms of aSyn, can cause familial forms of PD, it is still unclear whether increased levels of aSyn alone are sufficient to impair synaptic function. Previous studies have used experimental systems that do not allow systematic characterisation of presynaptic physiology. To address this gap in research, we used lentiviral vectors to overexpress human aSyn (haSyn) in continental and autaptic glutamatergic neurons from rodent hippocampus and systematically analysed their presynaptic function. Virally-transduced neurons exhibited levels of expression of haSyn that mimic those associated with triplications of the SNCA gene in PD patients (2-fold increase in total aSyn), as determined using quantitative immunofluorescence imaging and immunoblots. Neuronal toxicity, neuronal morphology, and SNAP-25, a presynaptic protein, were not altered in continental cultures. Finally, a systematic characterization of autaptic neurons expressing haSyn exhibited no significant difference in any parameter of synaptic function, including basal properties of evoked and spontaneous neurotransmitter release, and synaptic plasticity compared to neurons infected with a control virus. These results indicate that rodent glutamatergic neurons are resilient to aSyn overexpression. In conclusion, our findings suggest neurotoxicity associated with aSyn overexpression is not universal, and that a deeper understanding of aSyn biology and pathobiology is necessary.

neuroscience↗

bioRxiv2024

Highly adaptable deep-learning platform for automated detection and analysis of vesicle exocytosis

Vesicle exocytosis is a fundamental component of intercellular communication, in all organisms. It has been studied for decades, using various imaging tools. Nevertheless, exocytosis research is still limited by the lack of reliable automated analysis procedures. To address this, we developed the Intelligent Vesicle Exocytosis Analysis Platform (IVEA), a nearly universal solution for analyzing exocytosis acquired with live cell imaging. IVEA is applicable to a wide variety of experimental model systems, microscopes and reporter fluorophores. IVEA combines state-of-the-art deep-learning and computer vision regimes to enable fully automated analysis of large data. IVEA runs as a FIJI plugin and does not require prior training or human intervention. IVEA is 60 times faster than manual analysis and is able to detect rare events often missed by the human eye. Overall, IVEA represents a breakthrough in the analysis of cellular secretory mechanisms and has a transformative potential for the exocytosis imaging field.

bioengineering↗

bioRxiv2022

Expansion microscopy at one nanometer resolution

Fluorescence imaging is one of the most versatile and widely-used tools in biology1. Although techniques to overcome the diffraction barrier were introduced more than two decades ago, and the nominal attainable resolution kept improving2, 3, fluorescence microscopy still fails to image the morphology of single proteins or small molecular complexes, either purified or in a cellular context4, 5. Here we report a solution to this problem, in the form of one-step nanoscale expansion (ONE) microscopy. We combined the 10-fold axial expansion of the specimen (1000-fold by volume) with a fluorescence fluctuation analysis6, 7 to enable the description of cultured cells, tissues, viral particles, molecular complexes and single proteins. At the cellular level, using immunostaining, our technology revealed detailed nanoscale arrangements of synaptic proteins, including a quasi-regular organisation of PSD95 clusters. At the single molecule level, upon main chain fluorescent labelling, we could visualise the shape of individual membrane and soluble proteins. Moreover, conformational changes undergone by the [~]17 kDa protein calmodulin upon Ca2+ binding were readily observable. We also imaged and classified molecular aggregates in cerebrospinal fluid samples from Parkinsons Disease (PD) patients, which represents a promising new development towards improved PD diagnosis. ONE microscopy is compatible with conventional microscopes and can be performed with the software we provide here as a free, open-source package. This technology bridges the gap between high-resolution structural biology techniques and light microscopy, and provides a new avenue for discoveries in biology and medicine.

biophysics↗