Biology subjects

Kriston-Vizi, J.

Publications and source records attributed to Kriston-Vizi, J..

6 recordsLinked to original sources

bioRxiv2024

Functional analyses and integrated mechanisms of cellular destruction by L-amino acid oxidase

Snakebite accidents are prevalent worldwide and cause a spectrum of severe clinical manifestations and reduction of patient quality of life and economic income. L-amino acid oxidase (LAAO) is a highly toxic enzyme present in various venoms that causes tissue necrosis, oedema, coagulopathies, and organ failure. Here we investigate the mechanisms of LAAO cytotoxicity preceding cell death using recombinant LAAO and a catalytic inactive LAAO mutant. Wild-type LAAO uptake by cells leads to a decrease in lysosome number and size and inhibition of autophagy flux. Mitochondria function is impaired by severe proton leakage and mitochondrial fission is stimulated. Despite engulfment by autophagosomes, mitochondrial clearance is prevented by the lysosomal defects. The coordinate multi-organelle dysfunction strongly perturbs energy production, cell metabolism and clearance of defective organelles by autophagy, thereby triggering an irreversible destructive path. Considering the fast organelle impairment, strategies to reduce multi-organelle injury after LAAO exposure may be effective to maintain critical cell functions and strengthen adaptive responses against cytotoxicity.

cell biology↗

bioRxiv2023

Cardiac glycosides restore autophagy flux in an iPSC-derived neuronal model of WDR45 deficiency

Beta-Propeller Protein-Associated Neurodegeneration (BPAN) is one of the commonest forms of Neurodegeneration with Brain Iron Accumulation, caused by mutations in the gene encoding the autophagy-related protein, WDR45. The mechanisms linking autophagy, iron overload and neurodegeneration in BPAN are poorly understood and, as a result, there are currently no disease-modifying treatments for this progressive disorder. We have developed a patient-derived, induced pluripotent stem cell (iPSC)-based midbrain dopaminergic neuronal cell model of BPAN (3 patient, 2 age-matched controls and 2 isogenic control lines) which shows defective autophagy and aberrant gene expression in key neurodegenerative, neurodevelopmental and collagen pathways. A high content imaging-based medium-throughput blinded drug screen using the FDA-approved Prestwick library identified 5 cardiac glycosides that both corrected disease-related defective autophagosome formation and restored BPAN-specific gene expression profiles. Our findings have clear translational potential and emphasise the utility of iPSC-based modelling in elucidating disease pathophysiology and identifying targeted therapeutics for early-onset monogenic disorders.

cell biology↗

bioRxiv2022

Podoplanin expression in fibroblasts determines lymph node architecture and adaptive immune function

Lymph nodes are uniquely organised niches for immune interactions. Fibroblastic reticular cells (FRCs) facilitate immune cell communication and regulate immune function by producing growth factors, chemokines and inflammatory cues. Stromal expression of the glycoprotein Podoplanin (PDPN) is required for lymph node development, but the requirement for PDPN signaling in FRCs in adult lymph nodes has not been directly tested. Using a conditional in vivo deletion model PDGFRmGFP{Delta}PDPN, scRNA-seq revealed that PDPN deletion increased inflammatory signalling in lymph nodes and disrupted stromal-immune cells crosstalk in steady state and during adaptive immune responses. We confirmed that PDPN/CLEC-2 signaling in FRCs switches transcriptional states and alters expression of immune related genes. We conclude that Podoplanin expression impacts the immunoregulatory properties of fibroblastic stroma in lymph nodes and is a key transcriptional regulator of fibroblast function in lymph nodes. Summary: Podoplanin expression regulates the immunoregulatory properties of fibroblastic stroma in lymph nodes

immunology↗

bioRxiv2021

Vaccinia virus subverts xenophagy through phosphorylation and nuclear targeting of p62

Autophagy is an essential degradation program required to maintain cell homeostasis. Amongst its many functions is the engulfment and destruction of cytosolic pathogens, termed Xenophagy. Not surprisingly, many pathogens have adapted various strategies to circumvent or co-opt autophagic degradation during infection. For poxviruses, it is known that infection activates autophagy, which however is not required for successful replication. Despite the fact that these complex viruses replicate exclusively in the cytoplasm, autophagy-mediated control of poxvirus infection has not been explored. Using the prototypic poxvirus, vaccinia virus (VACV), we show that over-expression of the xenophagy receptors p62, NDP52 and Tax1Bp1 restricts poxvirus infection. While NDP52 and Tax1Bp1 were degraded, p62 was found to initially target cytoplasmic virions before being shunted to the nucleus. Nuclear translocation of p62 during infection was dependent upon p62 NLS2, and VACV kinase mediated phosphorylation of associated p62 residues T269/S272. These results indicate that VACV actively targets the xenophagy receptor p62 during the early stages of infection to avoid destruction, and further suggest that poxviruses exhibit a unique multi-layered control of autophagy in order to facilitate cytoplasmic replication.

microbiology↗

bioRxiv2020

Vaccinia virus hijacks ESCRT-mediated multivesicular body formation for virus egress

Unlike most enveloped viruses, poxvirus egress is a complex process whereby cytoplasmic single membrane-bound virions are wrapped in a cell-derived double membrane. These triple membrane-bound particles, termed intracellular enveloped virions (IEVs), are then released from infected cells by fusion. While the wrapping double membrane is thought to be derived from virus-modified trans-Golgi or early endosomal cisternae, the cellular factors that regulate virus wrapping remain largely undefined. To identify novel cell factors required for this process the prototypic poxvirus, vaccinia virus (VACV), was subjected to a high-throughput RNAi screen directed against cellular membrane trafficking proteins. Focusing on the endosomal sorting complexes required for transport (ESCRT), we demonstrate that ESCRT-III and VPS4 are required for packaging of virus into multivesicular bodies (MVBs). EM-based characterization of these MVB-IEVs showed that they account for half of IEV production indicating that MVBs serve as a second major source of VACV wrapping membrane. These data support a model whereby, in addition to cisternae-based wrapping, VACV hijacks ESCRT-mediated MVB formation to facilitate virus egress and spread.

cell biology↗

bioRxiv2020

Modulation of endothelial organelle size as an antithrombotic strategy

It is long-established that Von Willebrand Factor (VWF) is central to haemostasis and thrombosis. Endothelial VWF is stored in cell-specific secretory granules, Weibel-Palade bodies (WPBs), uniquely rod-like exocytic organelles generated in a wide range of lengths (0.5 to 5.0 {micro}m). It has been shown that WPB size responds to physiological cues and pharmacological treatment and that, under flow, VWF secretion from shortened WPBs produces a dramatic reduction of platelet and plasma VWF adhesion to an endothelial surface. WPB-shortening therefore represents a novel target for antithrombotic therapy acting via modulation of VWF adhesive activity. To this aim, we screened a library of licenced drugs and identified several that prompt WPB size reduction. These compounds therefore constitute a novel set of potentially antithrombotic compounds. SummaryThe size of the endothelial secretory granules that store Von Willebrand Factor correlates with its activity, central to haemostasis and thrombosis. Here, human-licenced drugs that reduce the size of these secretory granules are identified, providing a set of novel potential anti-thrombotic compounds.

cell biology↗