Abstract
Cell migration requires precise spatial and temporal control of the actin cytoskeleton, which is regulated
by multiple actin binding proteins. Recent work has revealed adenomatous polyposis coli (APC) is a
potent actin nucleator in vitro and works collaboratively with formins to assemble actin filaments by a
‘Rocket Launcher’ mechanism (Breitsprecher et al., 2012). Further, it was found that APC‐mediated actin
nucleation occurs at focal adhesions, where it is critical for microtubule‐induce focal adhesion turnover
and directed cell migration (Juanes et al, 2017). These and other observations suggest that APC, formins,
and other key binding partners such as CLIP‐170 may work in concert to control actin assembly
underlying cell migration. Here, we have investigated how IQGAP mechanistically influences actin
assembly, alone and together with APC, formins, and CLIP‐170. IQGAP is a multi‐domain scaffolding
protein that bundles F‐actin, caps barbed ends, and binds directly to APC, the formin Dia1, and CLIP‐170.
Using TIRF microscopy, we have begun defining the effects of full‐length IQGAP on actin assembly
dynamics, alone and in the presence of these other factors. Our preliminary in vitro observations
suggest that IQGAP attenuates actin assembly by APC and Dia1, and consistent with these effects, RNAi
silencing of IQGAP in HeLa cells led to excessive actin accumulation at the leading edge. Thus, IQGAP
may restrain unregulated actin assembly at the leading edge until specific signals are received, and in
this manner spatially and temporally control cell migration.
by multiple actin binding proteins. Recent work has revealed adenomatous polyposis coli (APC) is a
potent actin nucleator in vitro and works collaboratively with formins to assemble actin filaments by a
‘Rocket Launcher’ mechanism (Breitsprecher et al., 2012). Further, it was found that APC‐mediated actin
nucleation occurs at focal adhesions, where it is critical for microtubule‐induce focal adhesion turnover
and directed cell migration (Juanes et al, 2017). These and other observations suggest that APC, formins,
and other key binding partners such as CLIP‐170 may work in concert to control actin assembly
underlying cell migration. Here, we have investigated how IQGAP mechanistically influences actin
assembly, alone and together with APC, formins, and CLIP‐170. IQGAP is a multi‐domain scaffolding
protein that bundles F‐actin, caps barbed ends, and binds directly to APC, the formin Dia1, and CLIP‐170.
Using TIRF microscopy, we have begun defining the effects of full‐length IQGAP on actin assembly
dynamics, alone and in the presence of these other factors. Our preliminary in vitro observations
suggest that IQGAP attenuates actin assembly by APC and Dia1, and consistent with these effects, RNAi
silencing of IQGAP in HeLa cells led to excessive actin accumulation at the leading edge. Thus, IQGAP
may restrain unregulated actin assembly at the leading edge until specific signals are received, and in
this manner spatially and temporally control cell migration.
| Original language | English |
|---|---|
| Article number | P1952 |
| Pages (from-to) | 605 |
| Journal | Molecular Biology of the Cell |
| Volume | 28 |
| Publication status | Published - 31 Jan 2017 |
| Event | 2017 Annual Joint Meeting of the American Society for Cell Biology and the European Molecular Biology Organization - Philadelphia, United States Duration: 2 Dec 2017 → 6 Dec 2017 |