Rocket Launcher Mechanism of Collaborative Actin Assembly Defined by Single-Molecule Imaging
Cytoskeleton Journal Club June 13, 2012 Presented by Suk Namgoong
Adenomanous Polypolis Coli (APC)• Main component of Wnt Signaling Pathway• In the absence of bounded Wnt on Wnt receptor, it forms ‘destruction complex’ for β-catanin, - mediates proteolytic degradation of β-catenin• By the bound of wnt into wnt receptor Frizzled, APC release β-catenin and β- catenin was translocated into nucleus and ctivated various Wnt target genes (Development, Morphogenesis, Cancers..)• Tumor Suppressor Gene - Mutations on APC gene cause a hereditary cancer syndrome called Familiar Adenomanous Polypolis (FAP) - Loss of APC functions by mutations has been found frequently colorectal cancers
Two different binding mode of Actin nucleatorsArp2/3 complex stay on the ‘pointed end’ (slow growing end) of actin filamentsFormins remains processively bound on ‘barbed end’ (fast growing end) How about APC? From which side of actin filaments it initiate actin nucleation?
Synergistic actin nucleations by APC and mDia1 (Cappuccino) Yeast Bnr1 – bud6 During the nucleation, Formins and other nucleation factors interact each other and synergize nucleations. But what will happen after nucleation? Do formins and other nucleators dissociate after nucleation? or formins carry all other stuffs along with elongation? (not likely, but we don‟t know yet)