EAPSI: Understanding the Contribution of Class I Myosins to Cellular Processes Involving Membrane Deformation

Barger Sarah R, Syracuse NY

Investigators

Abstract

Plant cells are bound by a rigid cell wall, yet animal cells rely only on a plasma membrane and the underlying meshwork of cytoskeletal fibers, called actin filaments, for support and stability. As the cell boundary, the plasma membrane both enables and restricts any shape changing process. Adherence of the plasma membrane to the actin meshwork beneath generates resistance to deformation but also allows cells to maintain complex shapes. Non-muscle Class I myosins are motor proteins capable of binding both plasma membrane and actin filaments; therefore, they may link the plasma membrane to the actin cytoskeleton. That Class I myosins are structurally conserved from yeast to humans is indicative of their functional importance. However, their precise role in processes involving membrane deformation, such as cell migration and phagocytosis, remains elusive. In collaboration with Dr. Nils Gauthier, an expert in membrane-cytoskeletal interactions at the Mechanobiology Institute at the National University of Singapore, this research will evaluate the participation of Class I myosins in membrane-cytoskeletal adhesion during physiologically important processes that involve membrane deformation. In this project, the strength of membrane-cytoskeletal attachment in macrophages (cells of the innate immune system) lacking Class I myosins will be measured using a calibrated optical tweezers system, which uses a focused laser to measure forces applied to microscopic objects. Cells will then be subjected to tests on cell motility, cell traction and cell spreading to assess membrane deformation ability. These experiments will also be performed on macrophages expressing truncated myosin constructs to further our understanding of the roles of the individual protein domains. With the expertise of Dr. Gauthier and the specialized core facilities of the Mechanobiology Institute, this work will shed light on the workings of an ancient motor protein and its role in moving the plasma membrane. This award is funded in collaboration with the National Research Foundation of Singapore.