Novel activators of Arp2/3 complex, JMY and WHDC1

• Applicant: Professorin Dr. Theresia Stradal
• Subject Area: Cell Biology
• Term: from 2009 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 14023866

Final Report Abstract

The project aimed at the characterization of Arp2/3 complex activators emerged from a project jointly headed by Klemens Rottner and Theresia Stradal during the first funding period that focused on the characterization of Arp2/3-complex actin assembly in the lamellipodium. Using fluorescence recovery after photobleaching (FRAP), it was confirmed that actin network turnover occurs from the lamellipodium edge in a treadmilling fashion, and demonstrated that Arp2/3 complex is incorporated at the lamellipodium tip, at sites coincident with accumulation of its lamellipodial activator WAVE complex. Moreover, the dynamics and turnover of members of the ADF/cofilin family, also analysed in this fashion, turned out incompatible with a role in nucleation. In addition, the groups dissected the relevance for lamellipodia protrusion of the actin filament and Arp2/3 complex binding protein cortactin by generating cortactin-deficient fibroblast cells and mice. Furthermore, a novel assay was developed to unambiguously assess the ability of various factors to assemble actin dependent and independent of Arp2/3 complex in vivo. Finally, the groups began to examine the relevance of Arp2/3 complex activators, especially of WAVE complex, WASH or JMY in pathogen invasion. These studies were completed in the project headed by Theresia Stradal in the second funding period, culminating in several publications on host cell invasion of the gram-negative bacterium Salmonella enterica Serovar Typhimurium.

Publications

• (2008) Arp2/3 complex interactions and actin network turnover in lamellipodia. EMBO J 27(7):982-92
  Lai FP, Szczodrak M, Block J, Faix J, Breitsprecher D, Mannherz HG, Stradal TE, Dunn GA, Small JV, Rottner K
  
• (2008) Free Brick1 is a trimeric precursor in the assembly of a functional wave complex. PLoS ONE 3(6):e2462
  Derivery E, Fink J, Martin D, Houdusse A, Piel M, Stradal TE, Louvard D, Gautreau A
  
• (2009) Cortactin promotes migration and platelet-derived growth factor-induced actin reorganization by signaling to Rho-GTPases. Mol Biol Cell 20(14):3209-23
  Lai FP, Szczodrak M, Oelkers JM, Ladwein M, Acconcia F, Benesch S, Auinger S, Faix J, Small JV, Polo S, Stradal TE, Rottner K
  
• (2010) Molecular dissection of Salmonella-induced membrane ruffling versus invasion. Cell Microbiol 12(1):84-98
  Hänisch J, Ehinger J, Ladwein M, Rohde M, Derivery E, Bosse T, Steffen A, Bumann D, Misselwitz B, Hardt WD, Gautreau A, Stradal TE, Rottner K
  
• (2011) Activation of a RhoA/Myosin II-Dependent but Arp2/3 Complex-Independent Pathway Facilitates Salmonella Invasion. Cell Host Microbe 9(4):273-85
  Hänisch J, Kolm R, Wozniczka M, Bumann D, Rottner K, Stradal TE
  
• (2011) Essential role for Abi1 in embryonic survival and WAVE2 complex integrity. Proc Natl Acad Sci USA 108:7022-7
  Dubielecka PM, Ladwein KI, Xiong X, Migeotte I, Chorzalska A, Anderson KV, Sawicki JA, Rottner K, Stradal TE, Kotula L
  
• (2011) High-resolution X-ray structure of the trimeric Scar/WAVE-complex precursor Brk1. PLoS ONE 6(6):e21327
  Linkner J, Witte G, Stradal TE, Curth U, Faix J
  
• (2011) Microtubules as platforms for assaying actin polymerization in vivo. PLoS ONE 6(5):e19931
  Oelkers JM, Vinzenz M, Nemethova M, Jacob S, Lai FP, Block J, Szczodrak M, Kerkhoff E, Backert S, Schluter K, Stradal TE, Small JV, Koestler SA, Rottner K
  
• (2011) Structural basis for complex formation between human IRSp53 and the translocated intimin receptor Tir of enterohemorrhagic E. coli. Structure 19(9):1294-306
  de Groot JC, Schluter K, Carius Y, Quedenau C, Vingadassalom D, Faix J, Weiss SM, Reichelt J, Standfuss-Gabisch C, Lesser CF, Leong JM, Heinz DW, Bussow K, Stradal TE
  
• (2011) Theoretical model for cellular shapes driven by protrusive and adhesive forces. PLoS Comput Biol 7(5):e1001127
  Kabaso D, Shlomovitz R, Schloen K, Stradal T, Gov NS
  
• (2013) Arp2/3 complex is essential for actin network treadmilling as well as for targeting of capping protein and cofilin. Mol Biol Cell 24(18):2861-75
  Koestler SA, Steffen A, Nemethova M, Winterhoff M, Luo N, Holleboom JM, Krupp J, Jacob S, Vinzenz M, Schur F, Schluter K, Gunning PW, Winkler C, Schmeiser C, Faix J, Stradal TE, Small JV, Rottner K