Deptartment of Molecular Biology and Biochemistry
Nelson Hall, A321, Busch Campus
Piscataway, NJ 08854
Control of cell division, microfilaments, cytokinesis, protein phosphorylatio,. cell transformation
MYPT controls phosphorylation of MLC (myosin light chain. a subunit of myosin II) by activating myosin phosphatase. Because phosphorylation levels of MLC determine the activity of myosin II (a motor protein responsible for cytokinesis), MYPT may be a key protein to control cytokinesis. We have demonstrated that MYPT is phosphorylated in a mitosis-specific way, resulting in the activation of MYPT during mitosis. We hypothesize that this activation may cause dephosphorylation of MLC and disassembly of stress fibers during prophase.
FAK is a tyrosine kinase prominently localized at focal adhesions and appears to be a primary mediator of integrin-mediated signal transduction. We have discovered that FAK is serine phosphorylated in a mitosis-specific way. This serine phosphorylation (but not tyrosine phosphorylation) causes the dissociation of FAK from CAS, which may result in inactivation of the FAK-mediated signaling. One effect of the inactivation may be the inhibition of cell spreading and migration during mitosis because FAK/CAS association has been implicated as a mediator of cell spreading and migration. Another possibility is that the FAK inactivation may block signals initiating apoptosis that might otherwise be triggered by cell detachment during mitosis. We will examine these possibilities by expressing mutant FAKs lacking mitosis-specific phosphorylation sites.