Biology and Biomedical Sciences: Molecular Cell Biology
Date of Award
Doctor of Philosophy (PhD)
Chair and Committee
John A Cooper
This dissertation describes the physiological role of the Capping Protein- CARMIL interaction in migrating cells. I establish the CARMIL-CP complex as a key regulator of lamellipodial actin assembly and of lamellipodial dynamics. Membrane ruffling at the leading edge of motile cells and macropinocytosis were also found to be dependent on the CARMIL1-CP interaction. This is consistent with macropinocytosis and ruffling being dependent on a functional and dynamic lamellipodium.: Kerr and Teasdale, 2009).
In chapter two I demonstrate that the CBR of CARMIL1 is competent to inhibit CP in cells. I show that overexpression of the CBR in cells leads to global CP inhibition, and leads to a phenotype that suggests a loss of CP function. The activity of full length CARMIL1 differed markedly from that of the CBR when overexpressed. Overexpression full length CARMIL1 in cells lead to grossly abnormal lamellipodial protrusions.
In this work I demonstrate that CARMIL has several functions which do not depend on CP. I show that CARMIL-1's localization to the plasma membrane does not depended on its ability to bind to CP. Further; the abnormal protrusions induced by CARMIL1 overexpression also do not depend on CARMILs ability to bind CP. I also demonstrate that the N-terminus of CARMIL1 is necessary for CARMIL1's ability to regulate Rac1. In addition, I uncovered further evidence in support of the hypothesis that lamellipodia are only marginally important for cell migration in HT-1080s.
In chapter three I produce a detailed phylogeny of the CARMIL Family. My phylogenetic analysis, uncovered new CARMIL domains common to all CARMILs and highlighted previously unconsidered structural differences in the CBR of protozoans and metazoans.
Edwards, Marc, "The Function of CARMIL1 in Migrating Cells" (2013). All Theses and Dissertations (ETDs). 1181.