Cell Motility, the Microfilament system and Profilin:Actin

We study non-muscle cell behavior with a focus on the organization and regulation of the microfilament system – a force generating machinery of proteins essential to eukaryotes and with actin as principal component. As an intimate component of the cell periphery, the microfilament system responds to receptor activation by forming surface-protruding actin containing processes such as lamellipodia and filopodia which are used for adhesion, contacts with other cells and for migration. The microfilament system also mediates intracellular movements of vesicles and macromolecular complexes, in addition actin and actin-binding proteins function in different nuclear processes. Profilin is one of several components controlling actin polymerization. With actin it forms the profilin:actin complex which is recruited to growing filament ends by various nucleation and elongation promoting factors (NEPFs) such as members of the WASP/Wave, Ena/VASP and formin families of proteins. The interaction with the NEPFs is mediated by profilin, which therefore is important for spatiotemporal regulation of actin polymerization. Profilin also binds the phosphoinositide lipids PIP2 and PIP3 further emphasizing its close association to the plasma membrane and receptor signaling. We search to understand how profilin:actin is brought to polymer-forming sites at the cell edge, what profilin does in the nucleus and how that relates to the actin remodeling that occurs at the plasma membrane as a consequence of various surface signaling events.

Keywords

Actin, profilin, cell motility, cell signalling

Selected publications

Grantham, J., Lassing, I., & Karlsson, R. (2012). Controlling the cortical actin motor.
Protoplasma. 249(4):1001-15

Johnsson, A.K., & Karlsson, R. (2012). Synaptotagmin 1 causes phosphatidyl inositol lipid-dependent actin remodeling in cultured non-neuronal and neuronal cells. Exp Cell Res. 318(2):114-26

Lassing, I., Hillberg, L., Höglund, A.S., Karlsson, R., Schutt, C., & Lindberg, U. (2010). Tropomyosin is a tetramer under physiological salt conditions. Cytoskeleton (Hoboken). 67(9):599-607

Lindberg, U., Karlsson, R., Lassing, I., Schutt, C.E., & Höglund, A.S. (2008). The microfilament system and malignancy. Semin Cancer Biol. 18(1):2-11