Akatay, A. A. | bioRxiv Science

bioRxiv2024

Tension-induced adhesion mode switching: the interplay between focal adhesions and clathrin-containing adhesion complexes

Integrin-based adhesion complexes are crucial in various cellular processes, including proliferation, differentiation, and motility. While the dynamics of canonical focal adhesion complexes (FAs) have been extensively studied, the regulation and physiological implications of the recently identified clathrin-containing adhesion complexes (CCACs) are still not well understood. In this study, we investigated the spatiotemporal mechanoregulations of FAs and CCACs in a breast cancer model. Employing single-molecule force spectroscopy coupled with live-cell fluorescence microscopy, we discovered that FAs and CCACs are mutually exclusive and inversely regulated complexes. This regulation is orchestrated through the modulation of plasma membrane tension, in combination with distinct modes of actomyosin contractility that can either synergize with or counteract this modulation. Our findings indicate that increased membrane tension promotes the association of CCACs at integrin V{beta}5 adhesion sites, leading to decreased cancer cell proliferation, spreading, and migration. Conversely, lower membrane tension promotes the formation of FAs, which correlates with the softer membranes observed in cancer cells, thus potentially facilitating cancer progression. Our research provides novel insights into the biomechanical regulation of CCACs and FAs, revealing their critical and contrasting roles in modulating cancer cell progression.

cancer biology↗

bioRxiv2022

Endocytosis at Extremes: Formation and Internalization of Giant Clathrin-coated Pits Under Elevated Membrane Tension

Internalization of clathrin-coated vesicles from the plasma membrane constitutes the major endocytic route for receptors and their ligands. Dynamic and structural properties of endocytic clathrin coats are regulated by the mechanical properties of the plasma membrane. Here, we used conventional fluorescence imaging and multiple modes of structured illumination microscopy (SIM) to image formation of endocytic clathrin coats within live cells and tissues of developing fruit fly embryos. High resolution in both spatial and temporal domains allowed us to detect and characterize distinct classes of clathrin-coated structures. For the first time, we show that membrane tension induces formation of giant coated pits (GCPs) that can be up to two orders of magnitude larger than the canonical clathrin-coated pits. GCPs take longer to form but their mechanism of curvature generation is the same as the canonical pits. We also demonstrate that GCPs can split into smaller fragments during internalization. Considering the supporting roles played by actin filament dynamics in clathrin-mediated endocytosis under mechanically stringent conditions, we suggest that local changes in the coat curvature driven by actin machinery can drive splitting and internalization of GCPs.

biophysics↗