Membrane organizers: SPFH Proteins
SPFH proteins (which include Stomatin, Prohibitin, Flotillin, and HflK/C) are vital for organizing important regions in cell membranes across various parts of the cell, such as the plasma membrane, mitochondria, and the endoplasmic reticulum. These proteins, which share a common SPFH domain, are involved in many key cell activities, including signaling, moving substances within the cell, and controlling processes like energy production and cell death. Despite their importance, how SPFH proteins work and regulate these activities is still not fully understood. These proteins help form structures in cell membranes that organize and support different cellular functions. Flotillin, a key member of this protein family, is particularly important for a type of cell process called clathrin-independent endocytosis, where it helps the cell take in materials. Flotillin forms scaffolds that support the membrane, helping it to create vesicles that transport cargo. This process is influenced by lipids like sphingomyelin and by chemical changes to the proteins, such as phosphorylation, which affects their ability to cluster together. However, how Flotillin interacts with the cytoskeleton and helps generate the forces needed for vesicle formation is still unclear. Our research aims to address these gaps by studying how Flotillin helps organize membranes and take in cargo in the cell.
Our research focuses on four key questions about how Flotillin works in cells:
- How does phosphorylation affect Flotillin’s structure and its interaction with membranes? Phosphorylation plays a critical role in Flotillin’s ability to help with endocytosis, but we don’t fully understand how this change affects Flotillin’s shape and function. We will use advanced imaging techniques to study these changes in detail.
- How do Flotillin microdomains create the forces needed for vesicle formation? Flotillin helps bend the membrane, which is essential for vesicle formation, but we don’t yet know how it generates the mechanical forces needed for this process. We will investigate this by studying the structure and behavior of Flotillin complexes, as well as the lipids involved in vesicle formation.
- How do Flotillin vesicles select what cargo they carry? We know that Flotillin helps transport different molecules in the cell, but the specific mechanisms behind this cargo selection are unclear. By using genetic techniques and advanced imaging, we will explore how Flotillin organizes and interacts with cargo inside the vesicles.
- How does Flotillin interact with the cytoskeleton to help move vesicles? Flotillin works with cytoskeleton to control vesicle movement, but we don’t yet know exactly how these interactions happen. We will use live-cell imaging and other techniques to map these interactions and understand how they affect vesicle movement.