Biology subjects

Lieschke, G. J.

Publications and source records attributed to Lieschke, G. J..

5 recordsLinked to original sources

bioRxiv2026

Ca2+-mediated protein citrullination regulates proliferation in the regenerating and malignant CNS

Unlike most adult mammals, regenerative vertebrates can awaken dormant neural stem cells in response to injury. Understanding how this process is regulated could guide strategies to activate stem cells for tissue repair and limit aberrant proliferation in cancers of the CNS. Here, using zebrafish injury models and high-speed live imaging, we identify hydrodynamically-activated Ca{superscript 2} signalling as a key driver of neural stem cell activation. Local injury-associated changes in CSF flow activate mechanoreceptors at the site of spinal cord lesions, triggering pulsatile Ca{superscript 2} activity and progenitor proliferation. We identify Ca{superscript 2}-regulated peptidylarginine deiminase enzymes (PADs) as key downstream effectors that citrullinate intracellular targets in a Ca{superscript 2}-dependent manner to drive progenitor activation. Finally, we show that PAD inhibitors suppress the growth of aggressive medulloblastoma cells in preclinical laboratory models. Together, these findings uncover a novel mechanism of proliferation control in the vertebrate CNS and highlight the value of regenerative studies for identifying therapeutic targets. Graphical Summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/701650v1_ufig1.gif" ALT="Figure 1"> View larger version (67K): org.highwire.dtl.DTLVardef@3b7a56org.highwire.dtl.DTLVardef@dcc81forg.highwire.dtl.DTLVardef@d6a208org.highwire.dtl.DTLVardef@127de86_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDamage signals trigger changes in cilia activity and CSF flow to create a transient hydrodynamic niche at the site of spinal cord injuries. C_LIO_LISpecialised CSF-contacting neurons detect altered CSF circulation and initiate a signalling relay that culminates in elevated Ca{superscript 2} activity within dormant neural progenitors. C_LIO_LICa{superscript 2}-activated PAD enzymes link Ca{superscript 2} signalling to cell cycle progression by citrullinating intracellular targets in a Ca{superscript 2}-dependent manner. C_LIO_LIPAD inhibition suppresses medulloblastoma growth in preclinical laboratory models, revealing a conserved regulatory mechanism with translational potential. C_LI

neuroscience↗

bioRxiv2024

Macrophage migration-dependent retraction fibers and migrasomes - a structural basis for spatiotemporal cytokine secretion.

Migrating cells leave behind trails of matrix-bound retraction fibers and migrasomes, but their cell-specific physiological functions are largely unknown. We comprehensively characterize retraction fibers and migrasomes of migrating macrophages in mouse and zebrafish in vitro and in vivo models. These structures share common and macrophage-centric components of tetraspanin enriched microdomains (TEMs) including tetraspanin 4 (TSPAN4), the integrin CD11b and the pTRAP, SCIMP; like TSPAN4, we show that SCIMP expression modulates retraction fiber and migrasome formation. In immune-activated migrating macrophages, rear-positioned recycling endosomes regulate the secretory trafficking of newly synthesized inflammatory cytokines into retraction fibers and migrasomes. Transmembrane TNF is delivered via SNARE-mediated carriers to the cell surface and to the surfaces of both retraction fibers and migrasomes, from where it can be released. Retraction fibers are thus newly identified here as cytokine secretion sites, and along with migrasomes they allow migrating macrophages to secrete more cytokine compared to stationary cells. Whereas cytokine secretion has been viewed as a process of ad hoc diffusion, instead, we reveal a new mechanism of migration-dependent, localized deposition and spatiotemporal release of bioactive cytokines from RFs and migrasomes. Cytokine deployment is thus organized in a constrained manner facilitating direct influence on local inflammatory responses.

cell biology↗

bioRxiv2024

A nox2 / cybb zebrafish mutant with defective neutrophil ROS production displays normal initial neutrophil recruitment to sterile tail injuries

Reactive oxygen species (ROS) are important effectors and modifiers of the acute inflammatory response, recruiting neutrophils to sites of tissue injury. In turn, neutrophils are both consumers and producers of reactive oxygen species. Stimulated neutrophils generate reactive oxygen species in an oxidative burst through the activity of a multimeric phagocytic NADPH oxidase complex. Mutations in the NOX2/CYBB (previously gp91phox) NADPH oxidase subunit are the commonest cause of chronic granulomatous disease, a disease characterized by infection susceptibility and an inflammatory phenotype. To model chronic granulomatous disease, we made a nox2/cybb zebrafish (Danio rerio) mutant and demonstrated it to have severely impaired neutrophil ROS production. Reduced early survival of nox2 mutant embryos indicated an essential requirement for nox2 during early development. In nox2/cybb zebrafish mutants, the dynamics of initial neutrophil recruitment to both mild and severe surgical tailfin wounds was normal, suggesting that excessive neutrophil recruitment at the initiation of inflammation is not the primary cause of the "sterile" inflammatory phenotype of chronic granulomatous disease patients. This nox2 zebrafish mutant adds to existing in vivo models for studying neutrophil reactive oxygen species function in development and disease.

immunology↗

bioRxiv2020

Macrophages provide a transient muscle stem cell niche via NAMPT secretion

Skeletal muscle is paradigmatic of a regenerative tissue that repairs itself via the activation of a resident stem cell1. Termed the satellite cell, these normally quiescent cells are induced to proliferate by ill-defined wound-derived signals2. Identifying the source and nature of these pro-regenerative cues has been hampered by an inability to visualise the complex cellular interactions that occur within the wound environment. We therefore developed a zebrafish muscle injury model to systematically capture satellite cell interactions within the injury site, in real time, throughout the repair process. This analysis identified that a specific subset of macrophages dwells within the injury, establishing a transient but obligate stem cell niche required for stem cell proliferation. Single cell profiling identified specific signals secreted from dwelling macrophages that include the cytokine, Nicotinamide phosphoribosyltransferase (NAMPT/Visfatin/PBEF). Here we show that NAMPT secretion from the macrophage niche is required for muscle regeneration, acting through the C-C motif chemokine receptor type 5 (CCR5) expressed on muscle stem cells. This analysis reveals that along with their well-described ability to modulate the pro-inflammatory and anti-inflammatory phases of wound repair, specific macrophage populations also provide a transient stem cell-activating niche, directly supplying pro-proliferative cues that govern the timing and rate of muscle stem cell-mediated repair processes.

cell biology↗

bioRxiv2019

β-glucan dependent shuttling of conidia from neutrophils to macrophages occurs during fungal infection establishment

The initial host response to fungal pathogen invasion is critical to infection establishment and outcome. However, the diversity of leukocyte-pathogen interactions is only recently being appreciated. We describe a new form of interleukocyte conidial exchange called \"shuttling\". In Talaromyces marneffei and Aspergillus fumigatus zebrafish in vivo infections, live imaging demonstrated conidia initially phagocytosed by neutrophils were transferred to macrophages. Shuttling is unidirectional, not a chance event, involves alterations of phagocyte mobility, inter-cellular tethering, and phagosome transfer. Shuttling kinetics were fungal species-specific, implicating a fungal determinant. {beta}-glucan serves as a fungal-derived signal sufficient for shuttling. Murine phagocytes also shuttled in vitro. The impact of shuttling for microbiological outcomes of in vivo infections is difficult to specifically assess experimentally, but for these two pathogens, shuttling augments initial conidial redistribution away from fungicidal neutrophils into the favourable macrophage intracellular niche. Shuttling is a frequent host/pathogen interaction contributing to fungal infection establishment patterns.

cell biology↗