Biology subjects

Zenitsky, G.

Publications and source records attributed to Zenitsky, G..

5 recordsLinked to original sources

bioRxiv2025

Prokineticin-2 Upregulates GDNF in Astrocytes and Pharmacological Modulation of PK2 Receptors offers Neuroprotection in Experimental Models of Parkinson's Disease

Despite a wealth of preclinical studies establishing neuroprotective and neurorestorative properties of glial cell-line-derived neurotrophic factor (GDNF) in animal models of Parkinsons disease (PD), clinical trials utilizing direct intracranial infusion of GDNF protein, or adeno-associated virus (AAV)-mediated GDNF gene transfer has not achieved the desired efficacy, largely due to challenges in delivery methods. Given GDNFs strong potential for neuroprotection, alternative strategies to elevate its expression by beyond invasive injection or genetic manipulation remain a promising therapeutic avenue for PD. We previously reported that prokineticin signaling provides a compensatory protective response against dopaminergic neuronal degeneration in cell and animal models of PD. Herein, we report a novel finding that PK2 regulates GDNF gene expression in astrocytes, suggesting that PK2 signaling can be harnessed for neuroprotection in PD. Treatment of cultured astrocytes with the PK2 protein, PK2 gene overexpression or prokineticin receptor 1 (PKR1) agonist IS20 significantly induced the GDNF gene expression and the protein secretion, resulting in enhanced dopaminergic cell survival in cell culture models of PD. Importantly, systemic administration of IS20 through intraperitoneal or intranasal routes elevated GDNF levels in the mouse brain, including the nigrostriatal system. Furthermore, IS20 treatment conferred significant neuroprotective effects in both 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced and MitoPark transgenic mouse models of PD. Collectively, our translational findings suggest that pharmacological modulation PK2 signaling may unlock the full clinical benefit of GDNF, offering a novel and non-invasive therapeutic strategy for Parkinsons disease.

pharmacology and toxicology↗

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↗

bioRxiv2024

Mitochondrial dysfunction Impairs the Nuclear Pore Complex in Parkinson's Disease Pathogenesis

The mislocalization of transcription factors and irregularities in the nuclear envelope of dopaminergic neurons affected by Parkinsons disease (PD) implicates the nuclear pore in disease pathogenesis. While mitochondrial dysfunction is an integral component of PD pathophysiology, the involvement of channel-forming nucleoporins (Nups) in mitochondrial dysfunction-related neurodegeneration has not been investigated. Here we have identified pathological changes in the levels and distribution of a set of Nups, which are key structural and functional components of the nuclear pore complex, in dopaminergic neuronal models of PD. We observed that mitochondrial dysfunction reduces the expression of these Nups and disrupts the localization of Ran GTPase in both in vitro and in vivo dopaminergic neuron models. Furthermore, the nuclear pore central channel component, Nup62, mislocalizes and accumulates in the cytoplasm of these neurons under mitochondrial stress conditions. Mitochondrial stress also interferes with classical nuclear export of proteins in dopaminergic neural cells. Notably, we observed Nup pathology and Ran gradient loss in nigral dopaminergic neurons of PD patient brains, which highlights the clinical relevance of nuclear pore dysfunction as a disease mechanism. These findings provide direct evidence of the critical role of Nup-related abnormalities in mitochondrial dysfunction-induced degeneration of dopaminergic neurons, ultimately connecting nuclear pore complex and nucleocytoplasmic transport dysregulation to cell death in the development of PD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=158 HEIGHT=200 SRC="FIGDIR/small/622143v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@193d8acorg.highwire.dtl.DTLVardef@176135forg.highwire.dtl.DTLVardef@f1edceorg.highwire.dtl.DTLVardef@1338d9d_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

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↗