Biology subjects

Alik, A.

Publications and source records attributed to Alik, A..

5 recordsLinked to original sources

bioRxiv2025

Pro-inflammatory role of granzyme K producing bystander CD8+ T cells in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of blood malignancies with a 5-year survival rate below 30%, highlighting the urgent need for more effective therapeutic strategies. T cell-based immunotherapies have demonstrated remarkable success in solid tumors, yet the role of CD8+ T cells in AML remains unclear. In this study, we analyzed the composition, antigenic specificity, and function of CD8+ T cells in paired blood and bone marrow samples from AML patients. While we did not identify exhausted CD8+ T cells as seen in solid tumors, we observed a distinct population of functional CD69+ CD8+ T cells specifically enriched in the bone marrow. These cells primarily recognized non-tumor antigens, including epitopes derived from Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Notably, this bystander CD8+ T cell population showed high expression of Granzyme K, a cytokine found in the bone marrow of AML patients. Granzyme K did not induce leukemic cell death but instead promoted the secretion of IL-8, a pro-inflammatory cytokine known to play a detrimental role in AML pathology. Rather than mounting an anti-tumor response, these CD8+ T cells contribute to a pro-inflammatory environment that may exacerbate AML progression and severity. These findings provide a rationale for exploring therapeutic strategies aimed at inhibiting pro-inflammatory CD8+ T cells and targeting Granzyme K activity in association with actual therapies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/669682v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1fc9798org.highwire.dtl.DTLVardef@4491b1org.highwire.dtl.DTLVardef@1b8feadorg.highwire.dtl.DTLVardef@58515d_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Structural characterization of stem cell factors Oct4, Sox2, Nanog and Esrrb disordered domains, and a method to identify their phospho-dependent binding partners.

The combined expression of a handful of pluripotency transcription factors (PluriTFs) in somatic cells can generate induced pluripotent stem cells (iPSCs). Here, we report the structural characterization of disordered regions contained in four important PluriTFs, namely Oct4, Sox2, Nanog and Esrrb. Moreover, many post-translational modifications (PTMs) have been detected on PluriTFs, whose roles are not yet characterized. To help in their study, we also present a method i) to produce well-characterized phosphorylation states of PluriTFs, using NMR analysis, and ii) to use them for pull-downs in stem cell extracts analyzed by quantitative proteomics to identify of Sox2 binders.

biochemistry↗

bioRxiv2022

Human pericytes degrade alpha-synuclein aggregates in a strain-dependent manner

Parkinsons disease (PD) is a progressive, neurodegenerative disorder characterised by the abnormal accumulation of -synuclein (-syn) aggregates. Central to disease progression is the gradual spread of pathological -syn. -syn aggregation is closely linked to progressive neuron loss. As such, clearance of -syn aggregates may slow the progression of PD and lead to less severe symptoms. Evidence that non-neuronal cells play a role in PD and other synucleinopathies such as Lewy body dementia and multiple system atrophy are increasing. Our previous work has shown that pericytes -- vascular mural cells that regulate the blood-brain barrier -- contain -syn aggregates in human PD brains. Here, we demonstrate that pericytes efficiently internalise fibrillar -syn irrespective of being in a monoculture or mixed neuronal cell culture. Pericytes efficiently break down -syn aggregates in vitro, with clear differences in the number of -syn aggregates/cell and average aggregate size when comparing five pure -syn strains (Fibrils, Ribbons, fibrils65, fibrils91 and fibrils110). Furthermore, pericytes derived from PD brains have a less uniform response than those derived from control brains. Our results highlight the vital role brain vasculature may play in reducing -syn burden in PD.

neuroscience↗

bioRxiv2022

Dissecting aggregation and seeding dynamics of α-Syn polymorphs using the phasor approach to FLIM

Synucleinopathies are a heterogenous group of neurodegenerative diseases characterized by the progressive accumulation of pathological -synuclein (-Syn). The importance of structural polymorphism of -Syn assemblies for distinct synucleinopathies and their progression is increasingly recognized. However, the underlying mechanisms are poorly understood. Here we use fluorescence lifetime imaging microscopy (FLIM) to investigate seeded aggregation of -Syn in a biosensor cell line. We show that conformationally distinct -Syn polymorphs exhibit characteristic fluorescence lifetimes. FLIM further revealed that -Syn polymorphs were differentially processed by cellular clearance pathways, yielding fibrillar species with increased seeding capacity. Thus, FLIM is not only a powerful tool to distinguish different amyloid structures, but also to monitor the dynamic process of amyloid remodeling by the cellular environment. Our data suggest that the accumulation of highly seeding competent degradation products for particular polymorphs may account for accelerated disease progression in some patients.

molecular biology↗

bioRxiv2021

Impact of α-synuclein fibrillar strains and β-amyloid assemblies on mouse cortical neurons endo-lysosomal logistics

Endosomal transport and positioning are involved in establishing neuronal compartment architecture, dynamics and function, contributing to neuronal intracellular logistics. Furthermore, endo-lysosomal dysfunction has been identified as a common mechanism in neurodegenerative diseases. Here, we analyzed endolysosomal transport following the external application of -synuclein (-syn) fibrillar polymorphs, {beta}-amyloid (A{beta}) fibrils and oligomers on primary cultures of mouse cortical neurons. We used a simple readout to measure this transport: the spontaneous endocytosis of fluorescent nanodiamonds -- a perfectly stable nano-emitter -- in cultured neurons. We then performed a high-throughput automatic extraction and quantification of the directed motions of these nanodiamonds. -syn fibrillar polymorphs, A{beta} fibrils and oligomers halved the proportion of nanodiamonds transported along microtubules, but only slightly decreased their interactions with cortical neurons. This large decrease in endosomal transport would be expected to have a huge impact on neuronal homeostasis. We then assessed lysosomal dynamics with Lysotracker. The exposure of neurons to A{beta} oligomers led to an increase in the number of lysosomes, a decrease in the fraction of moving lysosomes and an increase in their size, reminiscent of findings for the APP transgenic model of Alzheimers disease. We then analyzed the effect of -syn fibrillar polymorphs, A{beta} fibrils and oligomers on endosomal and lysosomal transport and quantified the directed transport of these assemblies within cortical neurons. We report different impacts on endosomal and lysosomal transport parameters and differences in trajectory length for cargoes loaded with pathogenic protein assemblies. Our results suggest that the internalization and transport of intraneuronal pathogenic protein aggregates are potential targets for novel neuroprotective treatment strategies. Significance StatementNeurodegenerative diseases (NDs) are characterized by the deposition of protein aggregates with broad-range neuronal toxicity. Defects of endolysosomal trafficking are increasingly being seen as key pathological features of NDs, probably contributing to synaptic dysfunction and ultimate neuronal death. We used fast fluorescence videomicroscopy to investigate endosomal and lysosomal dynamics in the branches of mouse cortical neurons in primary cultures following the application of -syn fibrillar polymorphs (fibrils and ribbons) and A{beta} assemblies (oligomers and fibrils). We provide new insight into the differential effects of these pathogenic protein assemblies on endosomal and lysosomal transport, and reveal differences in the transport characteristics of the compartments loaded with these protein assemblies relative to endosomes.

neuroscience↗