Biology subjects

Gorka, O.

Publications and source records attributed to Gorka, O..

3 recordsLinked to original sources

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↗