A novel function of WW domain binding protein 2 (WBP2) in regulating cytoskeletal function and cellular division through binding to co-chaperone BAG3

Tuesday, October 25, 2011 — Poster Session II
Noon – 2:00 p.m.	Natcher Conference Center	NCI	CELLBIO-15

* FARE Award Winner

Authors

• A McCollum
• M Angelos
• E Kohn

Abstract

The BAG protein family is characterized by a C-terminal BAG domain that binds to the ATPase domain of Hsp70/Hsc70. BAG3 also contains an N-terminal tryptophan domain (WW), which we have shown binds to F-actin and co-localizes with actin filaments during G2 and M phases of the cell cycle. We hypothesized binding of a novel interacting protein to the BAG3 WW domain regulates BAG3-F-actin binding. We identified WBP2, a WW domain binding protein with no known function, as a novel BAG3 interactor. WBP2 was pulled down with GST-WW, but not GST control, indicating a specific interaction between WBP2 and the BAG3 WW domain. BAG3 and WBP2 co-immunoprecipitated in G1 and S phases, but not G2 or M. Silencing of WBP2 results in BAG3 co-immunoprecipitation with F-actin indiscriminately across all cell cycle phases, indicating that association with WBP2 prevents BAG3 binding to F-actin during specific cell cycle phases. We are the first to identify a function for the novel BAG3-interacting protein WBP2, which our data show regulates the BAG3 WW-domain association with the actin cytoskeleton in a cell cycle specific manner. Our findings show a novel mechanism through which regulation of BAG3 location drives proper cell division.

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