Biology subjects

Sokolova, D.

Publications and source records attributed to Sokolova, D..

7 recordsLinked to original sources

bioRxiv2025

Correlative evaluation of anticancer effects of a modified methioninase MGL-KPV using 2D and 3D cell models, human cancer xenografts in zebrafish embryos and Balb/c nude mice

PurposeThe emergence of new models of tumor growth requires a comparison of the results of the evaluation of the anticancer effect of single drug candidate for the selection of a relevant model. MethodsWe assessed the anticancer activity of the modified enzyme MGL-KPV using four models: 2D cultures, 3D spheroids, zebrafish embryo xenografts, and Balb/c nude mice. Cytotoxicity was tested in cancer cell lines and fibroblasts; efficacy was evaluated in zebrafish and mice. The effect of MGL does not require direct contact with cancer cells, making it unique drug candidate for in vitro and in vivo comparison. ResultsMGL-KPV showed selective cytotoxicity with IC50 values of 0.23-2.21 U/mL (2D) and 1.43-4.82 U/mL (3D), sparing fibroblasts. HCT-116 and Panc-1 were most sensitive. In zebrafish xenografts, tumor size reduced by 70% (HCT-116) and 43% (Panc-1); in mice -- by 45% and 34%, respectively. ConclusionsMGL-KPV demonstrated significant anticancer activity across all models. These results support step-by-step non-clinical proof-of-concept studies approach for amino-acid cleaving enzymes with anticancer properties.

pharmacology and toxicology↗

bioRxiv2024

C1q and immunoglobulins mediate activity-dependent synapse loss in the adult brain

C1q, the initiating protein of the classical complement cascade, mediates synapse loss in development and disease. In various mouse models of neurologic diseases, including Alzheimer's disease, C1q, which is secreted by microglia, the brain's resident macrophages, is found deposited on synapses in vulnerable brain regions. However, what underlies C1q deposition on synapses in the adult brain is unclear. Using in vivo chemogenetics, we demonstrate that neuronal hyperactivity acts as a trigger for region-specific deposition of C1q, which is required for activity-dependent synapse loss. Further, using spatial transcriptomics, live cell tracking, super-resolution microscopy and other molecular and cellular tools, we report a role for B lymphocyte lineage cells and immunoglobulins in the activity-dependent C1q deposition and synapse loss. Overall, our work suggests a link between neuronal hyperactivity and C1q-mediated synapse loss in the adult brain and introduces immunoglobulins as players in this process.

neuroscience↗

bioRxiv2024

Astrocyte-derived MFG-E8 facilitates microglial synapse elimination in Alzheimer's disease mouse models

Region-specific synapse loss is an early pathological hallmark in Alzheimers disease (AD). Emerging data in mice and humans highlight microglia, the brain-resident macrophages, as cellular mediators of synapse loss; however, the upstream modulators of microglia-synapse engulfment remain elusive. Here, we report a distinct subset of astrocytes, which are glial cells essential for maintaining synapse homeostasis, appearing in a region-specific manner with age and amyloidosis at onset of synapse loss. These astrocytes are distinguished by their peri-synaptic processes which are bulbous in morphology, contain accumulated p62-immunoreactive bodies, and have reduced territorial domains, resulting in a decrease of astrocyte-synapse coverage. Using integrated in vitro and in vivo approaches, we show that astrocytes upregulate and secrete phagocytic modulator, milk fat globule-EGF factor 8 (MFG-E8), which is sufficient and necessary for promoting microglia-synapse engulfment in their local milieu. Finally, we show that knocking down Mfge8 specifically from astrocytes using a viral CRISPR-saCas9 system prevents microglia-synapse engulfment and ameliorates synapse loss in two independent amyloidosis mouse models of AD. Altogether, our findings highlight astrocyte-microglia crosstalk in determining synapse fate in amyloid models and nominate astrocytic MFGE8 as a potential target to ameliorate synapse loss during the earliest stages of AD.

neuroscience↗

bioRxiv2023

Being spontaneous has its costs! Characterization of the spontaneous phage ΦD5-resistant mutants of Dickeya solani strain IPO 2222

Lytic bacteriophages able to infect and kill Dickeya spp. can be readily isolated from virtually all Dickeya spp.-containing environments, yet little is known about the selective pressure those viruses exert on their hosts. Here, we identified two spontaneous D. solani IPO 2222 mutants (0.8% of all obtained mutants), DsR34 and DsR207, resistant to infection caused by lytic phage vB_Dsol_D5 ({Phi}D5) that expressed a reduced ability to macerate potato tuber tissues compared to the wild-type, phage-susceptible D. solani IPO 2222 strain. Genome sequencing revealed that genes encoding: secretion protein HlyD (mutant DsR34) and elongation factor Tu (EF-Tu) (mutant DsR207) were altered in these strains. Both mutations impacted the proteomes of cells grown in both rich and minimal media, including the abundance of the cell envelope and transmembrane transport-associated proteins. Furthermore, features essential for the ecological success of these mutants in a plant environment, including their ability to use various carbon and nitrogen sources, produce plant cell wall degrading enzymes, ability to form biofilms, siderophore production, swimming and swarming motility and virulence in planta were assessed. Compared to the wild-type strain, D. solani strain IPO 2222, mutants DsR34 and DsR207 had a reduced ability to macerate chicory leaves and to colonize and cause symptoms in growing potato plants. The implications of the {Phi}D5 resistance on driving traits affecting the ecological performance of D. solani are discussed.

microbiology↗

bioRxiv2022

Microglia Detect Externalized Phosphatidylserine on Synapses for Elimination via TREM2 in Alzheimer's Disease Models

Genetic studies implicate phagocytosis pathways in microglia to be a major Alzheimers disease (AD)-associated process. Microglia phagocytose synapses in AD mouse models, suggesting a role for microglia in region-specific synapse loss, a pathological hallmark of AD. However, whether specific synapses are targeted for elimination, and if so, how, remains to be elucidated. Here, we show that synapses externalize phosphatidylserine (PtdSer) upon challenge by {beta}-amyloid oligomers, which are then selectively engulfed by microglia. Mechanistically, we find that Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) is critical for microglia to sense and preferentially engulf AD synapses. In brains of mice and humans, TREM2 dysfunction leads to exacerbation of apoptotic synapses. Our work altogether suggests a fundamental role for microglia as brain-resident macrophages to remove damaged synapses in AD. We provide mechanistic insight into how TREM2 variants associated with increased risk of developing AD may contribute to defective microglia-synapse function. One-Sentence summaryMicroglia selectively engulf synapses in Alzheimer-like mouse brains via PtdSer-TREM2 signaling.

neuroscience↗

bioRxiv2022

Perivascular SPP1 Mediates Microglial Engulfment of Synapses in Alzheimers Disease Models

Microglia are phagocytes of the brain parenchyma, where they interact with neurons to engulf synapses in a context-dependent manner. Genetic studies in Alzheimers disease (AD) highlight dysfunctional phagocytic signaling in myeloid cells as disease-associated pathway. In AD models, there is a region-specific reactivation of microglia-synapse phagocytosis involving complement; however, what drives microglia-synapse engulfment remains unknown. Here, we show that SPP1 (Osteopontin), a glycoprotein associated with inflammation, is regionally upregulated and modulates microglial synaptic engulfment in AD mouse models. Ultrastructural examination revealed SPP1 expression predominantly by perivascular macrophages, a subtype of border-associated macrophages, in the hippocampus of mice and patient tissues. Cell-cell interaction networks of single-cell transcriptomics data suggested that perivascular SPP1 drives microglial functional states in the hippocampal microenvironment of AD mice. Absence of Spp1 expression resulted in failure of microglia to mediate synaptic phagocytosis. This study suggests a critical role for perivascular SPP1 in neuroimmune crosstalk in AD-relevant context.

neuroscience↗

bioRxiv2021

Genetic variability associated with OAS1 expression in myeloid cells increases the risk of Alzheimer's disease and severe COVID-19 outcomes

Genome-wide association studies of late-onset Alzheimers disease (AD) have highlighted the importance of variants associated with genes expressed by the innate immune system in determining risk for AD. Recently, we and others have shown that genes associated with variants that confer risk for AD are significantly enriched in transcriptional networks expressed by amyloid-responsive microglia. This allowed us to predict new risk genes for AD, including the interferon-responsive oligoadenylate synthetase 1 (OAS1). However, the function of OAS1 within microglia and its genetic pathway are not known. Using genotyping from 1,313 individuals with sporadic AD and 1,234 control individuals, we confirm that the OAS1 variant, rs1131454, is associated with increased risk for AD and decreased OAS1 expression. Moreover, we note that the same locus was recently associated with critical illness in response to COVID-19, linking variants that are associated with AD and a severe response to COVID-19. By analysing single-cell RNA-sequencing (scRNA-seq) data of isolated microglia from APPNL-G-F knock-in and wild-type C57BL/6J mice, we identify a transcriptional network that is significantly upregulated with age and amyloid deposition, and contains the mouse orthologue Oas1a, providing evidence that Oas1a plays an age-dependent function in the innate immune system. We identify a similar interferon-related transcriptional network containing OAS1 by analysing scRNA-seq data from human microglia isolated from individuals with AD. Finally, using human iPSC-derived microglial cells (h-iPSC-Mg), we see that OAS1 is required to limit the pro-inflammatory response of microglia. When stimulated with interferon-gamma (IFN-{gamma}), we note that cells with lower OAS1 expression show an exaggerated pro-inflammatory response, with increased expression and secretion of TNF-. Collectively, our data support a link between genetic risk for AD and susceptibility to critical illness with COVID-19 centred on OAS1 and interferon signalling, a finding with potential implications for future treatments of both AD and COVID-19, and the development of biomarkers to track disease progression.

genetics↗