Biology subjects

Ignacz, A.

Publications and source records attributed to Ignacz, A..

3 recordsLinked to original sources

bioRxiv2025

Epigenetic small molecule screening identifies a new HDACi compound for ameliorating Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common inherited muscle disease. There are currently few effective therapies to treat the disease, although many approaches are being pursued. Certain histone deacetylase inhibitors (HDACi) have been shown to ameliorate DMD phenotypes in mouse and zebrafish animal models, and the HDACi givinostat has recently gained FDA approval for DMD. Our goal was to identify additional HDACi, or other classes of epigenetic small molecules, that are beneficial for DMD. Using an established animal model for DMD, the zebrafish dmd mutant strain sapje, we screened a library of over 800 epigenetic small molecules of various classes. We used a quantitative muscle birefringence assay to assess and compare the effects of these small molecule treatments on dmd mutant zebrafish skeletal muscle. Our screening identified a new HDACi, SR-4370, that ameliorated dmd mutant zebrafish skeletal muscle degeneration, in addition to HDACi previously shown to improve dmd zebrafish. We find that a single early treatment of HDACi can ameliorate dmd zebrafish. Furthermore, we find that HDACi that improve dmd muscle also cause increased histone acetylation in zebrafish larvae, whereas givinostat does not appear to increase histone acetylation or improve zebrafish dmd muscle. Our results add to the growing evidence that HDACi are promising candidates for treating DMD. Our study also provides further support for the effectiveness of small-molecule screening in dmd zebrafish. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/634796v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1f9f54aorg.highwire.dtl.DTLVardef@15707bborg.highwire.dtl.DTLVardef@bcafb5org.highwire.dtl.DTLVardef@1b3a8f7_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2022

Comparative analysis of actin visualization by genetically encoded probes in cultured neurons

Actin cytoskeleton predominantly regulates the formation and maintenance of synapses by controlling dendritic spine morphology and motility. To visualize actin dynamics, actin molecules can be labelled by genetically fusing fluorescent proteins to actin monomers or using fluorescently tagged actin-binding proteins or single-chain anti-actin antibodies. However, the effects of these labels on the morphology of neurons have not been quantitatively compared yet. In the present study, we analysed Actin-Chromobody-GFP, LifeAct-GFP and EGFP-actin with respect to their effects on actin-related features in mouse cultured hippocampal neurons. The actin-binding probes LifeAct and Actin-Chromobody showed similar affinity to F-actin, and along with EGFP-actin, were enriched in dendritic protrusions. In contrast to EGFP-actin, neither of these constructs was able to detect subtle changes in actin remodelling between mature mushroom shaped spine and less developed filopodia. None of the compared probes altered filopodial motility compared to control EGFP expression, however, within 24 hours expression, minor changes in dendritic spine morphology and density were visible. Furthermore, while EGFP-actin and LifeAct-GFP expression did not alter dendritic arborization, AC-GFP expressing neurons displayed a reduced dendritic arborization. We therefore conclude that careful consideration of cellular consequences is required before performing experiments with a particular actin labelling probe in primary neurons.

cell biology↗

bioRxiv2020

PKD promotes activity-dependent AMPA receptorendocytosis in hippocampal neurons

AMPA type glutamate receptors (AMPARs) mediate the majority of fast excitatory neurotransmission in the brain. The continuous trafficking of AMPARs into and out of synapses is a core feature of synaptic plasticity, which is considered as the cellular basis of learning and memory. The molecular mechanisms underlying the postsynaptic AMPAR trafficking, however, are still not fully understood. In this work, we demonstrate that the Protein Kinase D (PKD) family promotes basal and activity-induced AMPAR endocytosis in primary hippocampal neurons. Pharmacological inhibition of PKD increased synaptic levels of GluA1-containing AMPARs, slowed down their endocytic trafficking and increased neuronal network activity. By contrast, ectopic expression of constitutive active PKD decreased the synaptic level of AMPARs, while increasing their co-localization with early endosomes. Our results thus establish an important role for PKD in the regulation of postsynaptic AMPAR trafficking during synaptic plasticity.

neuroscience↗