Biology subjects

Rychlowski, M.

Publications and source records attributed to Rychlowski, M..

5 recordsLinked to original sources

bioRxiv2026

β4-integrins safeguard nuclear mechanics to suppress prostate cancer progression

Prostate cancer (PCa) progression is accompanied by profound alterations in cell-extracellular matrix (ECM) adhesion, nuclear architecture and mechanical adaptability, yet the molecular mechanisms linking these processes remain poorly understood. Hemidesmosomes (HDs), formed by 6{beta}4-integrins, anchor epithelial cells to the basement membrane and couple extracellular forces to the intermediate filament (IF) cytoskeleton. Here, we identify a previously unrecognized tumor-suppressive function of {beta}4-integrins in preserving nuclear integrity in prostate epithelial cells. Loss of {beta}4-integrins disrupted the cytokeratin-5 network and its coupling to the nucleus, leading to nuclear softening, lamin remodeling, reduced heterochromatin content and enhanced confined migration. Unexpectedly, proximity-labeling proteomics revealed that {beta}4-integrins engage nuclear pore complex (NPC) components in an 6-independent manner, particularly upon HD disassembly. Selected interactions were validated using proximity ligation and co-immunoprecipitation assays. {beta}4-integrin loss was associated with enlarged nuclear pores and aberrant nucleocytoplasmic transport, including nuclear accumulation of YAP1. Consistent with these findings, reduced {beta}4-integrin expression in a large PCa tissue cohort correlated with altered nuclear morphology, adverse clinicopathological features, metastatic progression, and poor patient survival. Collectively, our study establishes {beta}4-integrins as a critical molecular link between cell-ECM adhesion, nuclear mechanics and genome integrity.

cancer biology↗

bioRxiv2023

Harnessing light-activated gallium porphyrins to combat intracellular Staphylococcus aureus in dermatitis: Insights from a simplified model.

Staphylococcus aureus can survive inside nonprofessional phagocytes such as keratinocytes, demonstrating a novel strategy for evading antibiotic pressure. When antibiotic treatment ends, reinfection with staphylococci begins from the intracellular inoculum. This phenomenon is responsible for recurrent infections. The development of new antibacterial methods that can eliminate intracellular bacteria, including those with a multidrug-resistant phenotype, is necessary. In this study, we characterized and used a model of keratinocytes (both wild type and mutants with reduced filaggrin expression) infected with methicillin-resistant S. aureus (MRSA) to verify the possibility of using light-activated compounds, exemplified here by heme-mimetic gallium (III) porphyrin (Ga3+CHP) and visible light, an approach known as antimicrobial photodynamic inactivation (aPDI), to eliminate intracellular MRSA. We observed that Ga3+CHP accumulated more in infected cells than in uninfected cells. Moreover, Ga3+CHP accumulated in cells that harbored intracellular S. aureus. Using flow cytometry and fluorescence microscopy, we found that intracellular MRSA and Ga3+CHP mainly colocalized in lysosomal structures, and we showed that under the influence of aPDI, MRSA exhibited reduced adhesion to host cells and a significantly reduced (by 70%) GFP signal originating from intracellular bacteria. Moreover, the use of light-activated Ga3+CHP resulted in a significant reduction in the number of extracellular bacteria in the infection system, lowering the potential for further infection of host cells. For the first time, we used the infectious model to analyze the toxicity of aPDI in real time, showing that this approach is not significantly cyto-or phototoxic. Author SummaryStaphylococcus aureus is a highly virulent pathogen that is responsible for approximately 80% of all skin infections. During antibiotic treatment, one of the defense mechanisms of S. aureus is the invasion of keratinocytes. Intracellular bacteria are not accessible to antibiotics, which poorly penetrate the interior of host cells. Consequently, such bacteria contribute to recurrent infections. In our study, we proposed using a combination of a light-activated porphyrin compound loaded with gallium ions, Ga3+CHP, and visible light as a strategy to eliminate intracellular staphylococci. We demonstrated that the tested compound colocalized with the pathogen in the infected cells, which was an essential condition for the effective elimination of intracellular bacteria. We showed that the proposed approach effectively reduced the infection of keratinocytes with methicillin-resistant S. aureus (MRSA), as well as its adhesion to host cells, while maintaining host cells. The results presented here provide a basis for developing an effective therapy against staphylococci.

microbiology↗

bioRxiv2023

Pauperization of Emerin from nuclear envelope drives prostate cancer cell migration and invasiveness

Micronuclei (MN) can arise from many causes, including the breakage of aberrant cytokinetic chromatin bridge. The frequent observation of MN in tumors raises the specter that they might not merely be passive elements but could instead play active roles in tumor progression. Here, we test the hypothesis that the presence of micronuclei could induce specific phenotypic and functional changes to the cell and lead to increased cancer invasive potential. With a variety of imaging and molecular methods in vitro and in clinical samples from prostate cancer (PCa) patients, we show that chromosome bridge resolution can lead to EMD accumulation and formation of EMD-rich MN. Such structure is negative for Lamin A/C and positive for LBR and Sec6{beta}. It can cause EMD pauperization from NE affecting migratory and invasive properties of a cell and can be translated to PCa patients poor prognosis.

cancer biology↗

bioRxiv2023

Balanced Interplay Between Hsp110, Hsp70 and Class B J-Domain Protein Improves Aggregate Disassembly

Hsp70 is a key cellular system counteracting protein misfolding and aggregation, associated with stress, ageing and disease. Hsp70 solubilizes aggregates and aids protein refolding through substrate binding and release cycles regulated by co-chaperones: J-domain proteins (JDPs) and Nucleotide Exchange Factors (NEFs). Here, we elucidate the collaborative impact of Hsp110 NEFs and different JDP classes throughout Hsp70-dependent aggregate processing. We show that Hsp110 plays a major role at initial stages of disaggregation, determining its final efficacy. The NEF catalyses the recruitment of thick Hsp70 assemblies onto aggregate surface, which modifies aggregates into smaller species more readily processed by chaperones. Hsp70 stimulation by Hsp110 is much stronger with Class B than Class A JDPs and requires the auxiliary interaction between Class B JDP and the Hsp70 EEVD motif. Furthermore, we demonstrate for the first time that Hsp110 disrupts the JDP-Hsp70 interaction. Such destabilisation of chaperone complexes at the aggregate surface might improve disaggregation, but also lead to the inhibition above the substoichiometric Hsp110 optimum. Thus, balanced interplay between the co-chaperones and Hsp70 is critical to unlock its disaggregating potential.

biochemistry↗

bioRxiv2022

Major Histocompatibility Complex class I heavy chains localize in both cytoplasmic and nuclear compartment

The Major Histocompatibility Complex class I (MHC-I) molecules present antigenic peptides (AP) to CD8+ T cells for self versus non-self recognition. Loading of AP on MHC-I takes place in the endoplasmic reticulum (ER), upon shuttling of cytoplasmic AP substrates to the ER. Understanding of this process has been influenced by the view that MHC-I antigens are produced from the proteasomal degradation of cellular proteins. Recent observations on the intronic and untranslated region-derived peptides as well as on the non-AUG translation products presented on the MHC-I open the possibility that antigenic peptides can derive from pre-spliced mRNAs translated in the nuclear compartment. In this brief report, we show that a fraction of human MHC-I molecules (human leukocyte antigens type A, HLA-A) is present in the nuclei of cells, in the proximity of histone H2B. With this finding, we hope to initiate a new direction of research on the nuclear role of MHC-I and ask whether the loading of antigens can take place in the nuclear compartment.

immunology↗