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Dr. Cocucci on Curvature in Endocytic Clathrin Coats
Endocytic Clathrin Coats and Curvature: The episode kicks off with an introduction to endocytic clathrin coats. These are structures that form on a cell's surface to help internalize extracellular molecules. An essential step in this process involves curving a flat piece of the cell membrane into a vesicle, which the endocytosis machinery facilitates.
Initial Findings: Contrary to previous beliefs, the formation of clathrin pits doesn't depend on a late-stage flat-to-curved transition. The curvature actually starts developing from the early stages of their formation. This revelation challenges existing models of clathrin coat formation. Additionally, membrane tension, or the tautness of the cell surface, doesn't seem to affect how these clathrin pits generate curvature.
Use of Super-Resolved Imaging: Dr. Cocucci’s team employed advanced, super-resolved live cell fluorescence imaging to monitor clathrin-coated pit formation in real-time. This technique allowed them to observe these processes in both cultured cells and tissues of developing organisms with unparalleled clarity.
Flat-to-Curved Transition Models: Such models hypothesized that significant changes in clathrin coat structure were needed for vesicle formation. These changes would involve substantial alterations in the size (or "footprint") and brightness of the clathrin structures before domes and pits could form. However, Dr. Cocucci's observations challenge this idea. While they don't deny the possibility of such transitions, their data suggest a continuous curvature generation process from the outset of clathrin pit formation without any late-stage drastic transitions.
Role of CALM Adaptors: An intriguing observation was the distinct clustering of CALM adaptors beneath clathrin structures, while another protein, AP2, distributed more evenly. CALM is known to play a role in both detecting and driving curvature. The team proposes that these CALM clusters could increase local strain on the clathrin structures, potentially causing them to break and complete pit formation, especially at the edges.
Dr. Cocucci's groundbreaking work, backed by high-resolution imaging, offers a revised understanding of how clathrin-coated pits form and generate curvature on the cell membrane. By highlighting the early onset of curvature and the unique roles of CALM adaptors, this study has significant implications for our grasp of endocytosis and cell biology as a whole.
https://doi.org/10.1016/j.devcel.2021.10.019
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By Catarina CunhaEndocytic Clathrin Coats and Curvature: The episode kicks off with an introduction to endocytic clathrin coats. These are structures that form on a cell's surface to help internalize extracellular molecules. An essential step in this process involves curving a flat piece of the cell membrane into a vesicle, which the endocytosis machinery facilitates.
Initial Findings: Contrary to previous beliefs, the formation of clathrin pits doesn't depend on a late-stage flat-to-curved transition. The curvature actually starts developing from the early stages of their formation. This revelation challenges existing models of clathrin coat formation. Additionally, membrane tension, or the tautness of the cell surface, doesn't seem to affect how these clathrin pits generate curvature.
Use of Super-Resolved Imaging: Dr. Cocucci’s team employed advanced, super-resolved live cell fluorescence imaging to monitor clathrin-coated pit formation in real-time. This technique allowed them to observe these processes in both cultured cells and tissues of developing organisms with unparalleled clarity.
Flat-to-Curved Transition Models: Such models hypothesized that significant changes in clathrin coat structure were needed for vesicle formation. These changes would involve substantial alterations in the size (or "footprint") and brightness of the clathrin structures before domes and pits could form. However, Dr. Cocucci's observations challenge this idea. While they don't deny the possibility of such transitions, their data suggest a continuous curvature generation process from the outset of clathrin pit formation without any late-stage drastic transitions.
Role of CALM Adaptors: An intriguing observation was the distinct clustering of CALM adaptors beneath clathrin structures, while another protein, AP2, distributed more evenly. CALM is known to play a role in both detecting and driving curvature. The team proposes that these CALM clusters could increase local strain on the clathrin structures, potentially causing them to break and complete pit formation, especially at the edges.
Dr. Cocucci's groundbreaking work, backed by high-resolution imaging, offers a revised understanding of how clathrin-coated pits form and generate curvature on the cell membrane. By highlighting the early onset of curvature and the unique roles of CALM adaptors, this study has significant implications for our grasp of endocytosis and cell biology as a whole.
https://doi.org/10.1016/j.devcel.2021.10.019