Mical in Actin Regulation

Science Signaling  03 Jan 2012:
Vol. 5, Issue 205, pp. ec8
DOI: 10.1126/scisignal.2002808

Cell behavior is controlled by extracellular signals that work through signal transduction pathways to regulate the organization of the actin cytoskeleton. Some of these extrinsic signals positively affect the cytoskeleton and induce actin polymerization, but extrinsic signals that negatively regulate and disassemble actin filaments also exist. A family of multidomain proteins, the MICALs, directly associates with Semaphorins, cell surface receptors involved in negative or repulsive cues. Working with purified proteins and in vivo, Hung et al. now find that actin filaments serve as a direct substrate for Mical's enzymatic activity. Mical posttranslationally alters actin at its methionine 44 residue, which disrupts the association between actin monomers and cutting actin filaments. Altering the methionine 44 residue makes actin resistant to Mical-mediated disassembly in vitro and in vivo in Drosophila.

R.-J. Hung, C. W. Pak, J. R. Terman, Direct redox regulation of F-actin assembly and disassembly by Mical. Science 334, 1710–1713 (2011). [Abstract] [Full Text]