Biology subjects

Krecsmarik, M.

Publications and source records attributed to Krecsmarik, M..

5 recordsLinked to original sources

bioRxiv2026

Extracellular vesicles from triple negative breast cancer cells disrupt the blood-brain barrier via miR-146a-5p- and TGF-β1-mediated downregulation of endothelial Paqr5

Brain metastases are a common and often fatal complication of certain cancer types, such as triple-negative breast cancer. However, the molecular pathways driving brain metastasis formation, including the migration of cancer cells from the bloodstream to the brain parenchyma across the blood-brain barrier, are not yet fully defined. Therefore, using highly relevant mouse and human model systems, the mechanisms by which triple-negative breast cancer cells and their released extracellular vesicles modulate the blood-brain barrier-forming endothelium to increase its permissiveness to tumour cell entry into the brain are investigated. It is observed that extracellular vesicles derived from tumour cells are taken up by cerebral endothelial cells, where they induce miR-146a-5p- and TGF-{beta}1-mediated downregulation of PAQR5/mPR{gamma}, a membrane progesterone receptor. This, in turn, leads to disruption of interendothelial tight junctions, particularly through repression of claudin-5 expression, a critical protein for maintaining barrier function. Altogether this identifies a novel mechanism by which triple-negative breast cancer-derived extracellular vesicles compromise blood-brain barrier integrity, thereby facilitating transendothelial migration of cancer cells and promoting brain metastasis development. Moreover, this study is the first to highlight the role of membrane progesterone receptors in regulating the blood-brain barrier. Table of contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/701753v2_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@113c0a8org.highwire.dtl.DTLVardef@1cd5625org.highwire.dtl.DTLVardef@1d2b3c2org.highwire.dtl.DTLVardef@178a97_HPS_FORMAT_FIGEXP M_FIG Extracellular vesicles from triple-negative breast cancer cells induce miR-146a-5p- and TGF-1-mediated downregulation of PAQR5/mPR{gamma}, a membrane progesterone receptor, in blood-brain barrier-forming endothelial cells. This results in disruption of interendothelial tight junctions, thereby promoting enhanced migration of cancer cells into the brain. This mechanism highlights the role of membrane progesterone receptors in regulating the blood-brain barrier. C_FIG

cancer biology↗

bioRxiv2024

Gamma-TuRC proteins contribute to the dynamic organization of MTOCs during Drosophila spermatogenesis

The initiation of microtubule formation is facilitated by {gamma}-tubulin and {gamma}-Tubulin Ring Complex ({gamma}-TuRC) in various microtubule-organizing centers (MTOCs). While the heterogeneity of tissue-specific MTOCs and {gamma}-TuRC in Drosophila testis has been described, their molecular composition and physiological significance are poorly understood. We investigated the testis-specific distribution and biochemical interaction of the canonical {gamma}-TuRC proteins Grip163 and Grip84. We found that while Grip163 is present on the centrosome and basal body, Grip84 localizes to the centrosome and Golgi in spermatocytes and colocalizes with the testis-specific {gamma}-TuRC at the basal body, apical nuclear tip, and near the elongated mitochondria after meiosis. We also show the apical nuclear tip localization of some {gamma}-TuRC interacting partners and prove their binding to testis-specific {gamma}-TuRC proteins. These results highlight and prove the importance of the different {gamma}-TuRCs in organizing the diverse MTOCs present during the extensive rearrangement of cell organelles during the spermatogenesis of Drosophila.

cell biology↗

bioRxiv2020

Dynamic spatiotemporal coordination of neural stem cell fate decisions through local feedback in the adult vertebrate brain

Neural stem cell (NSC) populations persist in the adult vertebrate brain over a life time, and their homeostasis is controlled at the population level. The nature and properties of these coordination mechanisms remain unknown. Here we combine dynamic imaging of entire NSC populations in their in vivo niche over weeks, pharmacological manipulations, mathematical modeling and spatial statistics, and demonstrate that NSCs use spatiotemporally resolved local feedbacks to coordinate their decision to divide. These involve a Notch-mediated inhibition from transient neural progenitors, and a dispersion effect from dividing NSCs themselves, exerted with a delay of 9-12 days. Simulations from a stochastic NSC lattice model capturing these interactions demonstrate that they are linked by lineage progression and control the spatiotemporal distribution of output neurons. These results highlight how local and temporally delayed interactions occurring between brain germinal cells generate self-propagating dynamics that maintain NSC population homeostasis with specific spatiotemporal correlations.

neuroscience↗

bioRxiv2019

A zebrafish model for MonoMAC syndrome identifies an earlier role for gata2 in haemogenic endothelium programming and generation of haematopoietic stem cells

Haematopoietic stem and progenitor cells (HSPCs) maintain the vertebrate blood system throughout life and their emergence from haemogenic endothelium (HE) is regulated by transcription factors such as Gata2. Here we deleted a conserved enhancer (i4 enhancer) driving pan-endothelial expression of gata2a and showed that Gata2a is required for HE programming by regulating expression of runx1 and of the second zebrafish Gata2 orthologue, gata2b. By 5 days, homozygous gata2a{Delta}i4/{Delta}i4 larvae showed normal numbers of HSPCs, a recovery mediated by Notch signalling driving gata2b and runx1 expression in HE. However, gata2a{Delta}i4/{Delta}i4 adults showed oedema, susceptibility to infections and marrow hypo-cellularity, consistent with bone marrow failure found in GATA2 deficiency syndromes. Thus, gata2a expression driven by the i4 enhancer is required for HE programming in embryos and maintenance of steady-state haematopoietic stem cell output in the adult. These enhancer mutants are a new paradigm to explore the pathophysiology of GATA2-related deficiencies in vivo.

developmental biology↗

bioRxiv2017

An optimized pipeline for parallel image-based quantification of gene expression and genotyping after in situ hybridization

Advances in genome engineering have resulted in the generation of numerous zebrafish mutant lines. A commonly used method to assess gene expression in the mutants is in situ hybridization (ISH). Because the embryos can be distinguished by genotype after ISH, comparing gene expression between wild type and mutant siblings can be done blinded and in parallel. Such experimental design reduces the technical variation between samples and minimises the risk of bias. This approach, however, requires an efficient method of genomic DNA extraction from post-ISH fixed zebrafish samples to ascribe phenotype to genotype. Here we describe a method to obtain PCR-quality DNA from 95-100% of zebrafish embryos, suitable for genotyping after ISH. In addition, we provide an image analysis protocol for quantifying gene expression of ISH-probed embryos, adaptable for the analysis of different expression patterns. Finally, we show that intensity-based image analysis enables accurate representation of the variability of gene expression detected by ISH and that it can complement quantitative methods like qRT-PCR. By combining genotyping after ISH and computer-based image analysis, we have established a high-confidence, unbiased methodology to assign gene expression levels to specific genotypes, and applied it to the analysis of molecular phenotypes of newly generated lmo4a mutants.\n\nSUMMARY STATEMENTOur optimized protocol to genotype zebrafish mutant embryos after in situ hybridization and digitally quantify the in situ signal will help to standardize existing experimental designs and methods of analysis.

developmental biology↗