Biology subjects

Korunova, E.

Publications and source records attributed to Korunova, E..

3 recordsLinked to original sources

bioRxiv2026

Spatially Constrained Monte Carlo Permutation Test Reveals Diffusion Changes Near Stress Granules

Intracellular diffusion is inherently heterogeneous, yet single-particle tracking (SPT) analyses are often summarized using cell-wide average parameters that can obscure localized effects. Here, we tracked 40-nm genetically encoded multimeric (GEM) nanoparticles during stress granule (SG) formation and developed SPaCe-MC (Spatially Constrained Monte Carlo permutation test), a statistical framework that generates cytoplasm-specific null models to test whether diffusion associated with a specific cellular structure differs from that expected in the surrounding heterogeneous cytoplasm. Across three SG-inducing conditions, including oxidative stress, DDX3 inhibition, and combined treatment, bulk cytoplasmic analyses revealed distinct responses ranging from increased nanoparticle mobility to increased subdiffusive behavior. In contrast, SPaCe-MC consistently detected a local diffusion constraint in SG-associated regions relative to their treatment-matched cytoplasmic background, revealing a conserved local diffusion effect despite divergent global cytoplasmic responses. Together, our findings establish SPaCe-MC as a framework for identifying compartment-specific diffusion changes in heterogeneous cellular environments.

cell biology↗

bioRxiv2024

Single Particle Tracking of Genetically Encoded Nanoparticles: Optimizing Expression for Cytoplasmic Diffusion Studies

Single particle tracking (SPT) is a powerful technique for probing the diverse physical properties of the cytoplasm. Genetically encoded nanoparticles provide an especially convenient tool for such investigations, as they can be expressed and tracked in cells via fluorescence. Among these, 40-nm GEMs provide a unique opportunity to explore the cytoplasm. Their size corresponds to that of ribosomes and big protein complexes, allowing us to investigate the effects of the cytoplasm on the diffusivity of these objects while excluding the influence of chemical interactions during stressful events and pathological conditions. However, it has been shown that cytoplasmic viscosity is tightly regulated and plays a crucial role in maintaining homeostasis during protein synthesis and degradation. Despite this, the effects of GEM expression levels on diffusivity remain largely uncharacterized in mammalian cells. To optimize the GEMs tracking and estimate GEMs-expression effects we constructed dox-inducible GEM expression system and compare with a previously reported constitutive expression system. The optimized level of GEMs expression increases the measured diffusivity from 0.29 {+/-} 0.02 m2/sec in GEMs-overexpressed cells to 0.35 {+/-} 0.02 m2/sec; improve homogeneity throughout the cell population; and facilitates particle tracking. We also improved the analyses of GEM diffusivity by applying effective diffusion coefficient while considering the type of motion and assessing the heterogeneity in the type of motion by calculating the standard deviations of particle displacements. Statement of significanceDescribing cytoplasmic properties, such as environmental viscosity and protein complex motion, is essential for understanding molecular-level changes in cell function and pathology. A recently developed approach uses self-assembling fluorescent protein probes, expressed in cells, to investigate cytoplasmic properties through single-particle tracking (SPT). One such system employs genetically encoded multimeric (GEM) nanoparticles-- scaffold protein structures similar in size to ribosomes. This study addresses a key limitation in SPT of GEMs by examining how varying GEM expression levels affect measured diffusivity and tracking quality in mammalian cells. Our findings demonstrate that controlled GEM expression reduces particle overcrowding, increases measured diffusivity, and enhances track detection. This work contributes valuable insights into optimizing GEM nanoparticle applications for studying cytoplasmic viscosity and motion dynamics.

biophysics↗

bioRxiv2023

Suppression of HIV and cocaine-induced neurotoxicity and inflammation by cell penetrable itaconate esters

HIV-associated neurological disorder (HAND) is a serious complication of HIV infection, marked by neurotoxicity induced by viral proteins like Tat. Substance abuse exacerbates neurocognitive impairment in people living with HIV. There is an urgent need for effective therapeutic strategies to combat HAND comorbid with Cocaine Use Disorder (CUD). Our analysis of the HIV and cocaine-induced transcriptomes in primary cortical cultures revealed a significant overexpression of the macrophage-specific gene, aconitate decarboxylase 1 (Acod1), caused by the combined insults of HIV and cocaine. ACOD1 protein converts the tricarboxylic acid intermediate cis-aconitate into itaconate during the activation of inflammation. The itaconate produced facilitates cytokine production and subsequently activates anti-inflammatory transcription factors, shielding macrophages from infection-induced cell death. While the role of itaconate in limiting inflammation has been studied in peripheral macrophages, its immunometabolic function remains unexplored in HIV and cocaine-exposed microglia. We assessed in this model system the potential of 4-octyl-itaconate (4OI), a cell-penetrable esterified form of itaconate known for its potent anti-inflammatory properties and potential therapeutic applications. We administered 4OI to primary cortical cultures exposed to Tat and cocaine. 4OI treatment increased the number of microglial cells in both untreated and Tat{+/-}Cocaine-treated cultures and also reversed the morphological altercations induced by Tat and cocaine. In the presence of 4OI, microglial cells also appeared more ramified, resembling the quiescent microglia. Consistent with these results, 4OI treatment inhibited the secretion of the proinflammatory cytokines IL-1, IL-1{beta}, IL-6, and MIP1- induced by Tat and cocaine. Transcriptome profiling further determined that Nrf2 target genes such as NAD(P)H quinone oxidoreductase 1 (Nqo1), Glutathione S-transferase Pi (Gstp1), and glutamate cysteine ligase catalytic (Gclc), were most significantly activated in Tat-4OI treated cultures, relative to Tat alone. Further, genes associated with cytoskeleton dynamics in inflammatory microglia were downregulated by 4OI treatment. Together, the results strongly suggest 4-octyl-itaconate holds promise as a potential candidate for therapeutic development aimed at addressing HAND coupled with CUD comorbidities. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/559154v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@bfffa8org.highwire.dtl.DTLVardef@129ad8dorg.highwire.dtl.DTLVardef@1412ea2org.highwire.dtl.DTLVardef@5cb968_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO Model of 4OI-mediated neuroprotection against Tat-Cocaine toxicity Tat and Tat-Cocaine treatment induce neuronal damage, which is mitigated by 4OI through microglia cells. This cartoon shows the reduction of harmful effects such as proinflammatory cytokine release, upregulation of P2R, PDE, and Acod1 by the presence of 4OI. This ester modified itaconate triggers anti-inflammatory responses and activates antioxidant pathways. C_FIG

neuroscience↗