title: Nudel is crucial for the WAVE complex assembly in vivo by selectively promoting subcomplex stability and formation through direct interactions.
abstract: The WAVE regulatory complex (WRC), consisting of WAVE, Sra, Nap, Abi, and HSPC300, activates the Arp2/3 complex to control branched actin polymerization in response to Rac activation. How the WRC is assembled in vivo is not clear. Here we show that Nudel, a protein critical for lamellipodia formation, dramatically stabilized the Sra1-Nap1-Abi1 complex against degradation in cells through a dynamic binding to Sra1, whereas its physical interaction with HSPC300 protected free HSPC300 from the proteasome-mediated degradation and stimulated the HSPC300-WAVE2 complex formation. By contrast, Nudel showed little or no interactions with the Sra1-Nap1-Abi1-WAVE2 and the Sra1-Nap1-Abi1-HSPC300 complexes as well as the mature WRC. Depletion of Nudel by RNAi led to general subunit degradation and markedly attenuated the levels of mature WRC. It also abolished the WRC-dependent actin polymerization in vitro and the Rac1-induced lamellipodial actin network formation during cell spreading. Therefore, Nudel is important for the early steps of the WRC assembly in vivo by antagonizing the instability of certain WRC subunits and subcomplexes.
authors.affiliation: State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wu
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Yibo
authors.initials: Y
authors.lastname: Wu
authors.forename: Rong
authors.initials: R
authors.lastname: Zeng
authors.forename: Xueliang
authors.initials: X
authors.lastname: Zhu
mesh_terms: D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006207:Half-Life; D006367:HeLa Cells; D006801:Humans; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D058105:Polymerization; D025941:Protein Interaction Mapping; D055550:Protein Stability; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D034622:RNA Interference; D014162:Transfection; D051300:Wiskott-Aldrich Syndrome Protein Family / Q000235:genetics / Q000378:metabolism*; D012359:tRNA Methyltransferases
chemical_list: C513733:ABI1 protein, human; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C519848:BRK1 protein, human; C109916:CYFIP1 protein, human; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D046912:Multiprotein Complexes; C421108:NDEL1 protein, human; D011506:Proteins; C120152:WASF2 protein, human; D051300:Wiskott-Aldrich Syndrome Protein Family; C498548:TRMO protein, human; D012359:tRNA Methyltransferases