Biology subjects

Kolodziej, M.

Publications and source records attributed to Kolodziej, M..

4 recordsLinked to original sources

bioRxiv2024

Aberrant remodelling of astrocytic architecture in acute hepatic encephalopathy: complexity of oedematic atrophic astrocytes

Hepatic encephalopathy (HE) following acute liver failure (ALF) is a primary toxic astrocytopathy, although in-depth characterisation of underlying pathogenesis is far from complete. Among the multitude of astrocyte-specific proteins guiding brain functionality, plasmalemma-cytoskeletal linker ezrin, actin-binding protein profilin-1, and water channel aquaporin 4 (AQP4) contribute to astrocytic morphological plasticity through regulation of cell shape, volume, complexity of primary and terminal processes, and positioning astrocytes against other CNS constituents. Changes in these proteins might contribute to the brain oedema and astrocytic morphological remodelling in the HE. Using transmission electron microscopy, confocal fluorescent microscopy, and 3D reconstruction, we found complex morphological alterations of cortical astrocytes in mice with azoxymethane-induced ALF. Astrocytic primary branches demonstrated hypertrophy, whereas terminal leaflets showed atrophy quantified by the reduced area occupied by astrocytes, decreased number and the length of leaflets, decreased leaflets volume fraction, and altered astrocyte-to-neurone landscape. These morphological changes correlat with decreased expression of AQP4, phosphorylated leaflet-associated ezrin, and the actin dynamics regulator, profilin 1, suggesting the contribution of these proteins to astrocytic pathological remodelling. Pathological changes in astrocytes develop in parallel, and are likely causally linked to, the HE-linked neurological decline, manifested by a reduction in electroencephalography power and by excessive glutamate in the brain microdialysates. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/602491v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@45d6a3org.highwire.dtl.DTLVardef@10e9ac3org.highwire.dtl.DTLVardef@1d28b36org.highwire.dtl.DTLVardef@1b1b866_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract:C_FLOATNO Hepatic encephalopathy is associated with astrocyte remodelling manifested by swelling of the soma and primary branches together with atrophy of distal branches and leaflets; the latter retract from synapses thus affecting neurotransmission and contribute to the reduced neuronal activity. Astrocyte remodelling was linked to (and probably instigated by) a decrease of plasmalemma-cytoskeleton linker phosphorylated ezrin (Phos-ezrin), actin modulator profilin-1 (PFN1) and water channel aquaporin 4 (AQP4). C_FIG

neuroscience↗

bioRxiv2023

Deformed wings is an Atg8a-interacting protein that negatively regulates autophagy

LC3 (microtubule-associated protein 1 light chain 3, called Atg8 in yeast and Drosophila), is one of the most well-studied autophagy-related proteins. LC3 controls selectivity of autophagic degradation by interacting with LIR (LC3-interacting region) motifs also known as AIM (Atg8-interacting motifs) on selective autophagy receptors that carry cargo for degradation. Non-degradative roles of LIR motif-dependent interactions of LC3 are poorly understood. Here, we used yeast-two hybrid screening and Alpha Fold structural predictions, and we identified transcription factor Dwg (Deformed wings) as an Atg8a-interacting protein in Drosophila. Dwg-Atg8a interaction is LIR-motif dependent. We further show that Dwg is a negative regulator of autophagy. Our results provide novel insights on non-degradative roles of LIR motif dependent interactions of Atg8a and the transcriptional regulation of autophagy in Drosophila.

cell biology↗

bioRxiv2020

Lsr2 is a nucleoid-associated protein that exerts pleiotropic effects on mycobacterial cellular processes

Lsr2 is involved in maintaining chromosome structure in asymmetrically dividing mycobacteria and is essential in the tubercle bacillus (M. tuberculosis) during infection. Here, we report that a lack of Lsr2 profoundly impacts the mycobacterial cell morphology and the properties of the cell envelope resulting in the formation of smooth, short and antibiotics sensitive cells. Lsr2 forms large and dynamic nucleoprotein complexes in vivo and deletion of lsr2 gene exerts a profound effect on the replication time and replisome dynamics. We suggest that the Lsr2 nucleoprotein complexes may contribute to maintaining the proper organization of the newly synthesized DNA. Moreover, we demonstrate that the N-terminal oligomerization domain of Lsr2 is indispensable for the formation of nucleoprotein complexes in vivo. Collectively, our results indicate that Lsr2 exerts a pleiotropic effect on cellular processes and appears to be an attractive target for the development of a novel antitubercular drugs.

microbiology↗

bioRxiv2018

Watching antibiotics in action: Exploiting time-lapse microfluidic microscopy as a tool for target-drug interaction studies in Mycobacterium

Spreading resistance to antibiotics and the emergence of multidrug-resistant strains have become frequent in many bacterial species, including mycobacteria. The genus Mycobacterium encompasses both human and animal pathogens that cause severe diseases and have profound impacts on global health and the world economy. Here, we used a novel system of microfluidics, fluorescence microscopy and target-tagged fluorescent reporter strains of M. smegmatis to perform real-time monitoring of replisome and chromosome dynamics following the addition of replication-altering drugs (novobiocin, nalidixic acid and griselimycin) at the single-cell level. We found that novobiocin stalled replication forks and caused relaxation of the nucleoid, nalidixic acid triggered rapid replisome collapse and compaction of the nucleoid, and griselimycin caused replisome instability with subsequent over-initiation of chromosome replication and over-relaxation of the nucleoid. This work is an example of using a microscopy-based approach to evaluate the activity of potential replication inhibitors and provides mechanistic insights into their modes of action. Our system also enabled us to observe how the tested antibiotics affected the physiology of mycobacterial cells (i.e., growth, chromosome segregation, etc.). Because proteins involved in the DNA replication are well conserved among bacteria (including mycobacterial species), the properties of various replication inhibitors observed here in fast-growing M. smegmatis may be easily extrapolated to slow-growing pathogenic tubercle bacilli, such as M. tuberculosis.\n\nSignificanceThe growing problem of bacterial resistance to antibiotics and the emergence of new strains that are resistant to multiple drugs raise the need to explore new antibiotics and re-evaluate the existing options. Here, we present a system that allows the action of antibiotics to be monitored at the single-cell level. Such studies are important in the light of bacterial heterogeneity, which may be enhanced in unfavorable conditions, such as under antibiotic treatment. Moreover, our studies provide mechanistic insights into the action modes of the tested compounds. As combined therapies have recently gained increased interest, it is also notable that our described system may help researchers identify the best combination of antimicrobials for use against infections caused by a variety of bacteria.

microbiology↗