Biology subjects

Gorka, O.

Publications and source records attributed to Gorka, O..

6 recordsLinked to original sources

bioRxiv2025

NEK7 accelerates NLRP3 inflammasome activation

The NLRP3 inflammasome is a major driver of immunopathology, making it a sought-after drug target. In spite of two decades of intense research, its precise activation mechanism remains elusive, impeding inhibitor design. NEK7 was reported as essential for NLRP3 activation, and several newly identified inhibitors were suggested to act by interfering with their interaction. Here we report that NEK7 accelerates, but is in principle dispensable for NLRP3 activation. The onset of inflammasome activation was unaltered in the absence of NEK7, yet the rate of cells to undergo inflammasome formation and subsequent pyroptosis was approximately 4-fold reduced. Therefore, therapeutic targeting of the NEK7-NLRP3 interaction might have an incomplete effect, which should be considered for drug development. We confirmed entrectinib as a NEK7-dependent inhibitor, while other published compounds turned out not to rely on it. Our results support two possible scenarios for the role of NEK7 in NLRP3 activation: either, NEK7 accelerates one unique pathway of NLRP3 activation, or it is essential for a fast pathway, while being dispensable for a second, slower mode of NLRP3 activation.

immunology↗

bioRxiv2025

Vertical RAS-pathway inhibition in pancreatic cancer drives therapeutically exploitable mitochondrial alterations

Background & AimsOncogenic KRAS mutations drive metabolic rewiring in pancreatic ductal adenocarcinoma (PDAC). Src-homology 2 domain-containing phosphatase 2 (SHP2) is essential for full KRAS activity and promising dual SHP2/mitogen-activated protein kinase (MAPK) inhibition is currently being tested in clinical trials. Exploitable metabolic adaptations may contribute to an invariably evolving resistance. MethodsTo understand the metabolic changes induced by dual inhibition, we comprehensively tested cell lines, endogenous tumor models, and patient-derived organoids representing the full spectrum of PDAC molecular subtypes. ResultsWe find that dual SHP2/mitogen-activated protein kinase kinase (MEK1/2) inhibition induces major mitochondrial alterations, elevates reactive oxygen species (ROS) levels and triggers a lipid peroxidase dependency. While anabolic pathways, glycolysis and autophagy were also affected, mitochondrial alterations persisted longterm into a therapy resistant state. ConclusionsThe resulting vulnerability to induction of ferroptotic cell death via combined SHP2/MEK1/2 and glutathione peroxidase (GPX4) inhibition provides a metabolic lever to reinforce RAS-pathway inhibition for targeted PDAC treatment.

cancer biology↗

bioRxiv2024

Ubiquitin-specific protease 8 controls B cell proteostasis and cell survival in multiple myeloma

Ubiquitin-specific protease 8 (USP8) is a multifunctional deubiquitinating enzyme that plays a pivotal role in the regulation of endosomal and lysosomal trafficking. Several studies showed that USP8 is critically involved in the pathogenesis of various tumor entities. Recently, USP8 emerged as a vulnerability gene in multiple myeloma (MM), suggesting a functional role in the B- and plasma cell compartment. Here we have comprehensively analyzed mice with deletion of Usp8 at different stages of B-cell development. Furthermore, we evaluated the function of USP8 in proteasome inhibition susceptible and Bortezomib (BTZ) resistant patient derived MM cells using depletion of USP8 and treatment with DUB-IN-2, a widely used inhibitor published to target USP8. Usp8 depletion in Usp8f/fCd19-Cre mice affected B-cell survival and development favoring immature, innate-like B cells, and germinal center and plasma cells, while also elevating immune-responses and causing Roquin depletion. Cells expressing catalytically inactive USP8 accumulated proteins modified with mixed ubiquitin/NEDD8 chains, indicating proteotoxic stress. Moreover, we identified these modifications as preferred substrates of USP8. In MM cells, efficient USP8 knockdown reduced survival by inducing lysosomal dysfunction. In contrast, DUB-IN-2 induced an enhanced ER stress response to treatment with BTZ. Our results highlight the potential of targeting USP8 and the combination of DUB-IN-2 and BTZ in treating BTZ-resistant MM. However, our biochemical and cellular analyses raise fundamental concerns about the function of DUB-IN-2 as a USP8 inhibitor.

molecular biology↗

bioRxiv2023

Dual role of Toxoplasma gondii ROP5 and ROP18 for NLRP3 inhibition

Inflammasome activation leads release of IL-1{beta}, a proinflammatory cytokine that drives antimicrobial immune responses. Toxoplasma gondii has been shown to activate the NLRP3 inflammasome but the trigger has not yet been identified. Here we provide evidence that vacuolar disruption is a prerequisite for NLRP3 activation. T. gondii type I ROP5 and ROP18 protect the parasitophorous vacuolar membrane (PVM) and thereby inhibit inflammasome activation and IL-1{beta} release. Besides protection of the PVM, we demonstrate an additional function of ROP5 and ROP18 for NLRP3 inhibition. We demonstrate the molecular mechanism of this inhibition includes direct interaction with GBP5. In conclusion, T. gondii ROP5 and ROP18 inhibit IL-1{beta} production by protection of the intracellular replicative niche of the parasite and by actively subverting NLRP3 activation. Our findings provide further insight into the intricate mechanisms governing inflammasome activation and inhibition, enhancing our understanding of the complex dynamics during T. gondii infection. O_FIG O_LINKSMALLFIG WIDTH=155 HEIGHT=200 SRC="FIGDIR/small/558105v1_ufig1.gif" ALT="Figure 1"> View larger version (78K): org.highwire.dtl.DTLVardef@10a71b2org.highwire.dtl.DTLVardef@ae753eorg.highwire.dtl.DTLVardef@19365e7org.highwire.dtl.DTLVardef@74d9c_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2023

T helper cells exhibit a dynamic and reversible 3'UTR landscape.

3 untranslated regions (3UTRs) are critical elements of messenger RNAs, as they contain binding sites for RNA-binding proteins (RBP) and microRNAs that affect various aspects of the RNA life cycle including transcript stability and cellular localisation. In response to T cell receptor activation, T cells undergo massive expansion during the effector phase of the immune response and dynamically modify their 3UTRs. Whether this serves to directly regulate the abundance of specific mRNAs or is a secondary effect of proliferation remains unclear. To study 3UTR dynamics in T helper cells we investigated division-dependent alternative polyadenylation (APA). We generated 3 end UTR sequencing data from naive, activated, memory and regulatory CD4+ T cells. 3UTR length changes were estimated using a non-negative matrix factorization approach and were compared with those inferred from long-read PacBio sequencing. We found that APA events were transient and reverted after effector phase expansion. Using an orthogonal bulk RNAseq dataset, we did not find evidence of APA association with differential gene expression or transcript usage, indicating that APA has only a marginal effect on transcript abundance. 3UTR sequence analysis revealed conserved binding sites for T cell-relevant microRNAs and RBPs in the alternative 3UTRs. These results indicate that polyA site usage could play an important role in the control of cell fate decisions and homeostasis.

immunology↗

bioRxiv2022

Tyrosine kinase inhibitors trigger lysosomal damage-associated cell lysis to activate the NLRP3 inflammasome

Inflammasomes are intracellular protein complexes that control proteolytic maturation and secretion of inflammatory interleukin-1 (IL-1) family cytokines and are thus important in host defense. While some inflammasomes are activated simply by binding to pathogen-derived molecules, others, including those nucleated by NLRP3 and NLRP1, have more complex activation mechanisms that are not fully understood. We screened a library of small molecules to identify new inflammasome activators that might shed light on activation mechanisms. In addition to validating dipeptidyl peptidase (DPP) inhibitors as NLRP1 activators, we find that clinical tyrosine kinase inhibitors (TKIs) including imatinib and masitinib activate the NLRP3 inflammasome. Mechanistically, these TKIs cause lysosomal swelling and damage, leading to cathepsin-mediated destabilization of myeloid cell membranes and cell lysis. This is accompanied by potassium (K+) efflux, which activates NLRP3. Both lytic cell death and NLRP3 activation but not lysosomal damage induced by TKIs are prevented by the cytoprotectant high molecular weight polyethylene glycol (PEG). Our study establishes a screening method that can be expanded for inflammasome research and immunostimulatory drug development, and provides new insight into immunological off-targets that may contribute to efficacy or adverse effects of TKIs. One Sentence SummaryA functional small molecule screen identifies imatinib, masitinib and other tyrosine kinase inhibitors that destabilize myeloid cell lysosomes, leading to cell lysis and K+ efflux-dependent NLRP3 inflammasome activation.

immunology↗