Biology subjects

Paszek, M.

Publications and source records attributed to Paszek, M..

6 recordsLinked to original sources

bioRxiv2026

MTFP1 preserves β-cell cristae structure and bioenergetics to ensure insulin release and glucose homeostasis

Pancreatic {beta}-cells are uniquely dependent on mitochondrial metabolism to couple glucose sensing to insulin secretion, a process impaired in diabetes. Mitochondrial fission process 1 (MTFP1) is an inner mitochondrial membrane protein that plays pleiotropic, tissue-specific roles in mitochondrial function and dynamics. Our previous work has identified Mtfp1 mRNA as a target for miR-125b, a microRNA that negatively regulates insulin secretion from {beta}-cells. Nevertheless, the function of MTFP1 in these cells remained unexplored. Here, we show that MTFP1 is essential for normal glucose-stimulated insulin secretion (GSIS) in mouse and human cell lines and islets, and that mice with {beta}-cell-specific elimination of MTFP1 develop glucose intolerance. Whereas {beta}-cell survival and mitochondrial content were unaffected, oxidative phosphorylation and ATP production were sharply lowered. These changes were accompanied by disruption of mitochondrial cristae structure and a reduced contact surface with the endoplasmic reticulum, providing a mechanistic basis for defective stimulus-secretion coupling. Conversely, MTFP1 overexpression in mouse and human islets sufficed to improve mitochondrial respiration and GSIS. Finally, MTFP1 downregulation blocked the positive effects of miR-125b elimination in GSIS and mitochondrial respiration, unveiling MTFP1 as a downstream effector of miR-125b. Together, our findings identify MTFP1 as a critical regulator of {beta}-cell mitochondrial architecture and function, necessary for efficient insulin secretion and glucose homeostasis, and a potential therapeutic target to enhance {beta}-cell bioenergetic resilience in diabetes.

cell biology↗

bioRxiv2024

Biocompatibility of KAPs-Depleted Residual Hair

This work is an in-depth investigation of the in vitro and in vivo biocompatibility of processed and treated residual human hair samples with intact cuticle layers. The specimens included oxidized hair with no melanin (BLH) and hair with medium-(M-KAP) and low-(L-KAP) levels of keratin associated proteins (KAPs), confirmed through gel electrophoresis, electron microscopy, and trichrome histological staining, in comparison to the untreated regular hair (REG) control. All hair groups, high KAPs (H-KAPs: REG and BLH), M-KAP, and L-KAP, were found to be non-cytotoxic in the adipose fibroblast cell lines response to their extracts based on the ISO 10993-5 medical device biomaterial testing standard. In vivo mouse subcutaneous implantation (ISO 10993-6, local effects) at 2 weeks showed that the samples caused a foreign body response (FBR) with a thin fibrous encapsulation at a mean value of 28% relative skin dermis thickness; but notably, the L-KAP implant mitigated a statistically significant decrease in FBR area compared to H-KAPs (REG and/or BLH) and a lower number of cells, including immune cells of mostly macrophages and mast cells on the biomaterials surface, normalized to implant and tissue coverage. In the bulk of the capsules, blood vessels and collagen extracellular matrix densities were similar among groups. These findings suggest that small globular KAPs diffuse out of the cortex to the host-biomaterial interface which induce a slightly elevated FBR but limited to the implants surface vicinity. On-going follow-up research focuses on purer keratin-based macromolecularly organized residual hair biomaterials, those with depleted KAPs, for drug-delivery gel implants as they are deemed the most biocompatible. Statement of SignificanceHuman hair is an abundant biological product that is regularly discarded and wasted but has the potential to be a clinical implantable allograft biomaterial. There are currently just two FDA class II-510(k)-approved medical devices from hair, limited to surface / skin wound care use, and no class III-PMA or biologics-BLA implants. Also, these products and those in research and development phases are based on soluble keratin and KAPs extracts utilizing tedious processing conditions and requiring oxidation reaction for reassembly into gels and scaffolds. Here we describe that the insoluble residual hair biomaterials with organized keratin structure, higher-degree of disulfide crosslinks, and particularly those with depleted KAPs have increased biocompatibility based on pre-clinical ISO 10993 standards. This novel natural biomaterials are now being developed as drug-delivery implantable gels for clinical applications.

bioengineering↗

bioRxiv2023

The microenvironment dictates glycocalyx construction and immune surveillance

Efforts to identify anti-cancer therapeutics and understand tumor-immune interactions are built with in vitro models that do not match the microenvironmental characteristics of human tissues. Using in vitro models which mimic the physical properties of healthy or cancerous tissues and a physiologically relevant culture medium, we demonstrate that the chemical and physical properties of the microenvironment regulate the composition and topology of the glycocalyx. Remarkably, we find that cancer and age-related changes in the physical properties of the microenvironment are sufficient to adjust immune surveillance via the topology of the glycocalyx, a previously unknown phenomenon observable only with a physiologically relevant culture medium. Key PointsO_LICulture medium dictates cellular mechanoresponse signatures in vitro C_LIO_LIEpithelial glycocalyx construction is mediated by Heat Shock Factor 1 (HSF1) C_LIO_LISialic acid topology dictates Natural Killer cell cytotoxicity C_LIO_LIPhysiological microenvironments reveal distinct glycobiology C_LI

cell biology↗

bioRxiv2022

The Lamin A/C Ig-fold undergoes cell density-dependent changes that alter epitope accessibility

Lamins A/C are nuclear intermediate filament proteins that are involved in diverse cellular mechanical and biochemical functions. Here, we report that recognition of Lamins A/C by a commonly used antibody (JOL-2) that binds the Lamin A/C Ig-fold and other antibodies targeting similar epitopes is highly dependent on cell density, even though Lamin A/C protein levels do not change with cell density. The density-dependent Lamin A/C labeling was distinct from previously reported differential apico-basal labeling, which was independent of cell density. Comparison of the density-dependent labeling effects of antibodies recognizing different Lamin A/C epitopes suggests that the effect is caused by partial unfolding or masking of the CE and/or EF loops of the Ig-fold in response to cell spreading. Seeding cells on micropatterned surfaces with different areas confirmed that increased cell spreading resulted in reduced Lamin A/C labeling with the JOL-2 antibody. Surprisingly, JOL-2 antibody labeling was insensitive to depolymerization of cytoskeletal filaments or disruption of the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. Although the density-dependent changes of the Ig-fold did not alter nuclear stiffness or nucleo-cytoskeletal force transmission, they may nonetheless modulate interaction with lamin binding partners and thereby affect cellular functions. Taken together, our results point to a previously unrecognized change in the Lamin A/C Ig-fold that affects recognition by the JOL-2 antibody. These findings are not only important for the interpretation of immunofluorescence data for Lamin A/C, but also raise the intriguing prospect that the conformational changes may play a role in Lamin A/C mediated cellular function.

cell biology↗

bioRxiv2022

Biofunctional matrix models reveal mineral-dependent mechanoregulation of bone metastatic breast cancer

Bone metastasis is a leading cause of breast cancer-related deaths and often initiated by tumor cell dissemination to osteogenic niches. During new bone formation, osteoblasts first deposit osteoid, the collagen I-rich, unmineralized component of bone ECM, within which carbonated hydroxyapatite nanoparticles subsequently form. However, it remains elusive how bone matrix mineralization dictates tumor cell phenotype due in part to the lack of relevant model systems. Using biofunctional, collagen I-based bone matrix models with physiological, intrafibrillar mineralization, we show that mineralization inhibits proliferation, while inducing a stem-like phenotype in tumor cells. These changes were due to reduced mechanosignaling contradicting the conventional assumption that increased rigidity caused by mineralization stimulates metastatic progression. Our findings are translationally relevant as the presence of mineral reduced tumor growth in vivo and upregulated a gene signature that correlated with decreased patient mortality. Our results could help explain why decreased bone mineral density increases the risk for bone metastasis in patients and highlight that bone metastasis models should integrate organic and inorganic matrix components in a manner that mimics physiological mineralization.

bioengineering↗

bioRxiv2020

Nuclear deformation causes DNA damage by increasing replication stress

Cancer metastasis, i.e., the spreading of tumor cells from the primary tumor to distant organs, is responsible for the vast majority of cancer deaths. In the process, cancer cells migrate through narrow interstitial spaces substantially smaller in cross-section than the cell. During such confined migration, cancer cells experience extensive nuclear deformation, nuclear envelope rupture, and DNA damage. The molecular mechanisms responsible for the confined migration-induced DNA damage remain incompletely understood. While in some cell lines, DNA damage is closely associated with nuclear envelope rupture, we show that in others, mechanical deformation of the nucleus is sufficient to cause DNA damage, even in the absence of nuclear envelope rupture. This deformation-induced DNA damage, unlike nuclear envelope rupture-induced DNA damage, occurs primarily in S/G2 phase of the cell cycle and is associated with replication forks. Nuclear deformation, resulting from either confined migration or external cell compression, increases replication stress, possibly by increasing replication fork stalling, providing a molecular mechanism for the deformation-induced DNA damage. Thus, we have uncovered a new mechanism for mechanically induced DNA damage, linking mechanical deformation of the nucleus to DNA replication stress. This mechanically induced DNA damage could not only increase genomic instability in metastasizing cancer cells, but could also cause DNA damage in non-migrating cells and tissues that experience mechanical compression during development, thereby contributing to tumorigenesis and DNA damage response activation.

cell biology↗