Biology subjects

Swaminathan, V. S.

Publications and source records attributed to Swaminathan, V. S..

3 recordsLinked to original sources

bioRxiv2025

β1 Integrin-FAK-Piezo1 signalling axis drives in-situ stiffening mediated ECM remodelling and invasion of 3D breast epithelium

Stiffening of tissue is a hallmark of cancer progression, driving invasive phenotypes through complex interactions between cells and their extracellular matrix (ECM). However, the mechanisms linking mechanical cues to ECM remodelling and invasion remain incompletely understood. Here, using an in-situ stiffening model that allows for modulation of ECM stiffness around fully formed normal mammary acini embedded in their native ECM microenvironment, we identify critical steps in basement membrane (BM) and stromal ECM remodelling during invasion and discover the molecular mechanisms driving this process. We find that stiffening of the ECM around normal mammary acini results in rapid loss and degradation of laminin (LN) and upregulation of the fibronectin (FN) secretion around the acini. This priming phase is followed by the onset of invasion which requires localized upregulation of LN production and ECM remodelling. Mechanistically, ECM production and remodelling as well as invasion is mediated by {beta}1 integrin-FAK signalling, which activates mechanosensitive ion channels (MSCs). Further, we identify Piezo1 as the MSC downstream of {beta}1 integrin-FAK that drives BM disruption and stromal ECM remodelling. Taken together, our results identify the mechanisms by which stiffness can trigger invasive phenotypes from normal tissues.

cell biology↗

bioRxiv2024

Extracellular matrix dependent regulation of Septin 7 in focal adhesions promotes mechanosensing and response in fibroblasts.

Fibroblasts are contractile adherent cells that maintain tissue homeostasis by sensing a wide array of changes in the extracellular matrix (ECM) and in response, regulate the physical and compositional properties of the ECM. These diverse cues are sensed by focal adhesions (FAs) that differentially couple changes in the ECM to the actomyosin machinery via modulation of integrin activation and the resultant recruitment of several proteins. One such protein is Septin-7 (Sept-7) that belongs to the septin family and has been found in FA proteomics and interactome studies. Sept-7 however, is not considered an FA protein and is thought to regulate and be regulated by actin outside of FAs. To reconcile these differences, here we used total internal reflection microscopy to image Sept-7 localization and dynamics at the cell-ECM interface and found that that ECM-mediated integrin activation in fibroblasts regulates the formation of spatially distinct higher order Sept-7 structures at FA subpopulations. In and around FAs located in the perinuclear regions of the cell, ECM binding resulted in the formation and stabilization of Sept-7 bundles while ECM binding and complete integrin activation promoted the growth of FA-like elongated Sept-7 structures that dynamically associated with the core of peripheral FAs. Functionally, peripheral Sept-7 structures promoted the elongation of peripheral FAs while perinuclear Sept-7 bundles were critical in regulating the maturation and stabilization of perinuclear FAs. Due to this coupling between the ECM, integrin activation and regulation of Sept-7 structures, we found that Sept-7 is required for a wide range of ECM sensing functions in fibroblasts including modulating sensitivity to changes in ECM stiffness and density and in contributing to the cells ability to remodel the ECM. Collectively, our results show that Sept-7 is an FA protein that gets recruited and assembled in diverse higher order structures in an ECM dependent manner to differentially regulate FA subpopulations and promote mechanosensing and ECM remodelling functions in fibroblasts.

cell biology↗

bioRxiv2022

Extracellular matrix sensing via modulation of orientational order of integrins and F-actin in focal adhesions

Specificity of cellular responses to distinct cues from the extracellular matrix (ECM) requires precise and sensitive decoding of information from the cell surface. However, how known mechanisms of mechanosensing such as force dependent catch bonds and conformational changes in focal adhesion (FA) proteins can confer this sensitivity is not known. Using a combination of polarization microscopy and computational modeling, here we identify regulation of orientational order or molecular co-alignment of FA proteins as a mechanism able to precisely tune cell sensitivity to the ECM. We find that V integrins and F-actin in FAs show changes in orientational order in an ECM-mediated integrin activation dependent manner. This magnitude of orientational order is sensitive to changes in ECM density but independent of myosin-II activity though actomyosin contractility can further fine-tune it. A molecular clutch model for integrin binding ECM ligands demonstrates that orientational order of integrin-ECM binding and catch bonds tune cellular sensitivity to ECM density. This mechanism is also able to decouple ECM density changes from changes in ECM stiffness thus also contributing to specificity. Taken together, our results suggest relative geometric organization of FA components as an important regulator of mechanotransduction.

cell biology↗