Biology subjects

Malovic, E.

Publications and source records attributed to Malovic, E..

4 recordsLinked to original sources

bioRxiv2025

KCa3.1 Contributes to Neuroinflammation and Nigral Dopaminergic Neurodegeneration in Experimental models of Parkinson's Disease

Chronic neuroinflammation and misfolded -synuclein (Syn) have been identified as key pathological correlates driving Parkinsons disease (PD) pathogenesis; however, the contribution of ion channels to microglia activation in the context of -synucleinopathy remains elusive. Herein, we show that KCa3.1, a calcium-activated potassium channel, is robustly upregulated within microglia in multiple preclinical models of PD and, most importantly, in human PD and dementia with Lewy bodies (DLB) brains. Pharmacological inhibition of KCa3.1 via senicapoc or TRAM-34 inhibits KCa3.1 channel activity and the associated reactive microglial phenotype in response to aggregated Syn, as well as ameliorates of PD like pathology in diverse PD mouse models. Additionally, proteomic and transcriptomic profiling of microglia revealed that senicapoc ameliorates aggregated Syn-induced, inflammation-associated pathways and dysregulated metabolism in primary microglial cells. Mechanistically, FYN kinase in a STAT1 dependent manner regulates KCa3.1 mediated the microglial reactive activation phenotype after -synucleinopathy. Moreover, reduced neuroinflammation and subsequent PD-like neuropathology were observed in SYN AAV inoculated KCa3.1 knockout mice. Together, these findings suggest that KCa3.1 inhibition represents a novel therapeutic strategy for treating patients with PD and related -synucleinopathies.

neuroscience↗

bioRxiv2025

Exploring the Role of Kv1.3 and MAPK14 in Mediating Microglial Oxidative Stress and Neuroinflammation Following Organic Dust Exposure

BackgroundAgricultural contaminants, including inhaled organic dust (OD) and gases, are known to cause inflammation in the lungs and the brain. We investigated the role of the potassium channel Kv1.3 in organic dust (OD)-induced neuroinflammation models. Kv1.3 channels play a multifaceted role in microglial immune modulation, cancer, neurodegenerative diseases, and constitute a potential therapeutic target. MethodsWe used in vivo (C57BL/6 mice), in vitro (microglial cell line, primary microglia), and ex vivo (brain slice culture) models of OD-induced neuroinflammation. A sterile OD extract (ODE) was prepared, and mice were exposed to either normal saline or ODE intra-nasally for 5 weeks (5 days/week) to simulate an occupational exposure scenario. Primary microglia were isolated from neonatal mice for total RNA sequencing (RNA-seq). The ODE-induced expression of Kv1.3 was quantified using in vitro and ex vivo models with and without PAP-1 treatments. Exposure-induced changes in cytokines and reactive species markers were measured. Using western blot, we quantified phosphorylated p38 MAPK14 (p-p38 MAPK) and NOX2. We measured the currents through Kv1.3 channels using a microglial patch-clamp assay. ResultsExposure to ODE increased the expression of Kv1.3 and p-p38 MAPK in mouse microglia without affecting the Kv1.3 currents at the cell surface. Exposure increased the levels of inflammatory cytokines and NOX2. Kv1.3 inhibition with PAP-1 decreased inflammatory markers (TNF- and IL-6), levels of Kv1.3, p-p38 MAPK, NOX2, and nitrites. ConclusionOur study revealed that pharmacological inhibition of Kv1.3 potassium channels reduces ODE-induced neuroinflammation by decreasing inflammatory and oxidative stress markers.

pharmacology and toxicology↗

bioRxiv2024

Mitochondrial Stress Disassembles Nuclear Architecture through Proteolytic Activation of PKCδ and Lamin B1 Phosphorylation in Neuronal Cells: Implications for Pathogenesis of Age-related Neurodegenerative Diseases

Mitochondrial dysfunction and oxidative stress are hallmarks of pathophysiological processes in age-related neurodegenerative diseases including Parkinsons, Alzheimers and Huntingtons diseases. Neuronal cells are highly vulnerable to mitochondrial stress, however, the cellular and molecular mechanisms underlying the enhanced vulnerability are not well understood. Previously, we demonstrated that the novel PKC isoform PKC{delta} is highly expressed in dopamin(DA)ergic neurons and plays a key role in inducing apoptotic cell death during neurotoxic stress via caspase-3-mediated proteolytic activation. Herein, we further uncovered a key downstream molecular event of PKC{delta} signaling following mitochondrial dysfunction that governs neuronal cell death by dissembling nuclear architecture. Exposing N27 DAergic cell line to the mitochondrial complex-1 inhibitor tebufenpyrad induced PKC{delta} phosphorylation at the T505 activation loop accompanied by caspase-3-dependent proteolytic activation of the kinase. Subcellular analysis using high-resolution 3D confocal microscopy revealed that proteolytically activated cleaved PKC{delta} translocates to the nuclear compartment, colocalizing with Lamin B1. Electron microscopy also enabled the visualization of nuclear membrane damage triggered by subjecting the DAergic neuronal cells by Tebufenpyrad (Tebu) toxicity. In silico analyses identified that the threonine site on Lamin B1 (T575) is likely phosphorylated by PKC{delta}, suggesting that Lamin B1 serves as a key downstream target of the kinase. Interestingly, N27 DAergic cells stably expressing the PKC{delta} proteolytic cleavage site-resistant mutant failed to induce nuclear damage, PKC{delta} activation, and Lamin B1 phosphorylation. Furthermore, CRISPR/Cas9-based stable knockdown of PKC{delta} greatly attenuated Tebu-induced Lamin B1 phosphorylation. Also, studies using Lamin B1T575G mutated at phosphorylation and PKC{delta}-{Delta}NLS-overexpressing N27 cells showed that PKC{delta} activation and translocation to the nuclear membrane are critically required for phosphorylating Lamin B1 at T575 to induce nuclear membrane damage during Tebu insult. Additionally, Tebu failed to induce Lamin B1 damage and Lamin B1 phosphorylation in organotypic midbrain slices cultured from PKC{delta}-/- mouse pups. More importantly, we observed higher PKC{delta} activation, Lamin B1 phosphorylation and Lamin B1 loss in nigral DAergic neurons from the postmortem brains of PD patients as compared to age-matched healthy control brains, thus providing translational relevance of our finding. Collectively, our data reveal that PKC{delta} functions as a Lamin B1 kinase to disassemble the nuclear membrane during the neuronal cell death process triggered by mitochondrial stress. This mechanistic insight may have important implications for the etiology of age-related neurodegenerative diseases resulting from mitochondrial dysfunction as well as for the development of novel treatment strategies.

neuroscience↗

bioRxiv2024

Epitranscriptomic Reader YTHDF2 Regulates SEK1(MAP2K4)-JNK-cJUN Inflammatory Signaling in Astrocytes during Neurotoxic Stress

As the most abundant glial cells in the CNS, astrocytes dynamically respond to neurotoxic stress, however, the key molecular regulators controlling the inflammatory status of these sentinels during neurotoxic stress have remained elusive. Herein, we demonstrate that the m6A epitranscriptomic mRNA modification tightly regulates the pro-inflammatory functions of astrocytes. Specifically, the astrocytic neurotoxic stresser, manganese (Mn), downregulated the m6A reader YTHDF2 in human and mouse astrocyte cultures and in the mouse brain. Functionally, YTHDF2 knockdown augmented, while its overexpression dampened, neurotoxic stress induced proinflammatory response, suggesting YTHDF2 serves as a key upstream regulator of inflammatory responses in astrocytes. Mechnistically, YTHDF2 RIP-sequencing identified MAP2K4 (MKK4; SEK1) mRNA as a YTHDF2 target influencing inflammatory signaling. Our target validation revealed Mn-exposed astrocytes mediates proinflammatory response by activating the phosphorylation of SEK1, JNK, and cJUN signaling. Collectively, YTHDF2 serves a key upstream molecular switch controlling SEK1(MAP2K4)-JNK-cJUN proinflammatory signaling in astrocytes.

neuroscience↗