Protein complexes containing CYFIP/Sra/PIR121 coordinate Arf1 and Rac1 signalling during clathrin-AP-1-coated carrier biogenesis at the TGN.
Actin dynamics is a tightly regulated process involved in various cellular events including biogenesis of clathrin-coated, AP-1 (adaptor protein 1)-coated transport carriers connecting the trans-Golgi network (TGN) and the endocytic pathway. However, the mechanisms coordinating coat assembly, membrane and actin remodelling during post-TGN transport remain poorly understood. Here we show that the Arf1 (ADP-ribosylation factor 1) GTPase synchronizes the TGN association of clathrin-AP-1 coats and protein complexes comprising CYFIP (cytoplasmic fragile-X mental retardation interacting protein; Sra, PIR121), a clathrin heavy chain binding protein associated with mental retardation. The Rac1 GTPase and its exchange factor beta-PIX (PAK-interacting exchange factor) activate these complexes, allowing N-WASP-dependent and Arp2/3-dependent actin polymerization towards membranes, thus promoting tubule formation. These phenomena can be recapitulated with synthetic membranes. This protein-network-based mechanism facilitates the sequential coordination of Arf1-dependent membrane priming, through the recruitment of coats and CYFIP-containing complexes, and of Rac1-dependent actin polymerization, and provides complementary but independent levels of regulation during early stages of clathrin-AP1-coated carrier biogenesis.
Biotechnology Center, Dresden University of Technology, Tatzberg 47-51, 01307 Dresden, Germany.
Mihaela
M
Anitei
Christoph
C
Stange
Irina
I
Parshina
Thorsten
T
Baust
Annette
A
Schenck
Graça
G
Raposo
Tomas
T
Kirchhausen
Bernard
B
Hoflack
D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism*; D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D033961:Adaptor Protein Complex 1 / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002458:Cell Fractionation; D002522:Chlorocebus aethiops; D022163:Clathrin-Coated Vesicles / Q000378:metabolism*; D004705:Endocytosis; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D021381:Protein Transport; D034622:RNA Interference; D064067:Rho Guanine Nucleotide Exchange Factors; D013552:Swine; D013997:Time Factors; D014162:Transfection; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism*
C576606:ARHGEF7 protein, human; D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D033961:Adaptor Protein Complex 1; D048868:Adaptor Proteins, Signal Transducing; C109916:CYFIP1 protein, human; C518673:CYFIP2 protein, human; D020662:Guanine Nucleotide Exchange Factors; C107953:RAC1 protein, human; D064067:Rho Guanine Nucleotide Exchange Factors; C495771:WASL protein, human; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D020823:ADP-Ribosylation Factor 1; D020830:rac1 GTP-Binding Protein