Biology subjects

Winograd-Katz, S.

Publications and source records attributed to Winograd-Katz, S..

3 recordsLinked to original sources

bioRxiv2025

VASP regulates the polar organization of adhesion-associated actin filaments

Focal adhesions (FAs) are dynamic macromolecular assemblies that anchor the actin cytoskeleton to the extracellular matrix via integrin receptors, thereby regulating cell morphology and migration. Although FA maturation and organization have been extensively studied, it remains unclear how regulatory proteins influence the 3D architecture of FAs. Here, we show that loss of the vasodilator-stimulated phosphoprotein (VASP) impairs adhesion dynamics. We employed CRISPR/Cas9-mediated knockout of VASP and/or the mechanosensitive adaptor protein zyxin to investigate their respective roles in actin-adhesion coupling. Loss of VASP and zyxin correlates with altered FA morphology and impaired dynamics. Using cryo-electron tomography (cryo-ET), we resolved the polarity of individual actin filaments associated with FAs and identified a contractility-related actin layer enriched with tropomyosin. VASP and zyxin are required for the assembly of dense and aligned actin bundles with uniform polarity, oriented with their barbed ends towards the cell edge. In contrast, the tropomyosin-decorated dorsal actin layer remains unaffected by these perturbations. Our findings reveal distinct, layered architectures within FAs and underscore the cooperative role of VASP and zyxin in stabilizing the organization of actin filaments at functional adhesion sites.

cell biology↗

bioRxiv2021

The Serine Protease HtrA2 mediates radiation-induced senescence in cancer cells

Radiation therapy can induce cellular senescence in cancer cells leading to short-term tumor growth arrest, yet increased long-term recurrence. To better understand the molecular mechanisms involved, we developed a model of radiation-induced senescence in cultured cancer cells, which exhibited a typical senescent phenotype, including upregulation of p53 and its target p21, followed by sustained reduction in cellular proliferation, changes in cell size and cytoskeleton organization, and senescence-associated beta-galactosidase activity. A functional siRNA screen using a cell death-related library identified the mitochondrial Ser protease HtrA2 as necessary for senescence development. Mass spectrometry-based proteomic profiling of the senescent cells indicated downregulation of proteins involved in cell cycle progression and DNA repair, and upregulation of proteins associated with malignancy, while irradiation with HtrA2 inhibition upregulated cell proliferation components. In search of direct HtrA2 substrates following radiation, we determined that HtrA2 cleaves the intermediate filament protein vimentin, affecting its cytoplasmic organization. Ectopic expression of active cytosolic HtrA2 resulted in similar changes to vimentin filament assembly. Thus HtrA2, contributes to several hallmarks of senescence and is involved in the cytoskeletal reorganization that accompanies radiation-induced senescence. SummaryHere the authors identify the Ser protease HtrA2 as a novel mediator of radiation-induced senescence, necessary for sustained proliferation arrest and reorganization of the vimentin filament network.

cancer biology↗

bioRxiv2018

Massive osteopetrosis caused by giant, non-functional osteoclasts in R51Q SNX10 mutant mice

The molecular mechanisms that regulate fusion of monocytes into functional osteoclasts are virtually unknown. We describe a knock-in mouse model for the R51Q mutation in sorting nexin 10 (SNX10) that exhibits osteopetrosis and related symptoms of patients of autosomal recessive osteopetrosis linked to this mutation. Osteopetrosis arises in homozygous R51Q SNX10 mice due to a unique combination of reduced numbers of osteoclasts that are non-functional. Fusion of mutant monocytes is deregulated and occurs rapidly and continuously to form giant, non-functional osteoclasts. Mutant osteoclasts mature quickly and survive poorly in vitro, possibly accounting for their scarcity in vivo. These cells also exhibit impaired ruffled borders, which are required for bone resorption, providing an additional basis for the osteopetrotic phenotype. More broadly, we propose that the maximal size of osteoclasts is actively determined by a genetically-regulated, cell-autonomous mechanism that limits precursor cell fusion, and for which SNX10 is required.

cell biology↗