Date Published: July 3, 2013
Publisher: Public Library of Science
Author(s): Bruno Pontes, Yareni Ayala, Anna Carolina C. Fonseca, Luciana F. Romão, Racκele F. Amaral, Leonardo T. Salgado, Flavia R. Lima, Marcos Farina, Nathan B. Viana, Vivaldo Moura-Neto, H. Moysés Nussenzveig, Stefan FT. Weiss.
Recent studies indicate that the cell membrane, interacting with its attached cytoskeleton, is an important regulator of cell function, exerting and responding to forces. We investigate this relationship by looking for connections between cell membrane elastic properties, especially surface tension and bending modulus, and cell function. Those properties are measured by pulling tethers from the cell membrane with optical tweezers. Their values are determined for all major cell types of the central nervous system, as well as for macrophage. Astrocytes and glioblastoma cells, which are considerably more dynamic than neurons, have substantially larger surface tensions. Resting microglia, which continually scan their environment through motility and protrusions, have the highest elastic constants, with values similar to those for resting macrophage. For both microglia and macrophage, we find a sharp softening of bending modulus between their resting and activated forms, which is very advantageous for their acquisition of phagocytic functions upon activation. We also determine the elastic constants of pure cell membrane, with no attached cytoskeleton. For all cell types, the presence of F-actin within tethers, contrary to conventional wisdom, is confirmed. Our findings suggest the existence of a close connection between membrane elastic constants and cell function.
The cell membrane with its associated proteins, besides enclosing the cell internal environment and controlling endocytosis and exocytosis, takes part in a variety of vital processes, including molecule presentation and recognition, catalysis, signal sensing, cytokinesis, cell shaping and motility. Through its interaction with the cytoskeleton and motor proteins, it exerts and responds to forces , .
It is becoming increasingly apparent that the cell membrane, interacting with the attached cytoskeleton, is an important regulator of cell function , , , , , , , .