Phosphorylated YDXV motifs and Nck SH2/SH3 adaptors act cooperatively to induce actin reorganization.
We have analyzed the means by which the Nck family of adaptor proteins couples adhesion proteins to actin reorganization. The nephrin adhesion protein is essential for the formation of actin-based foot processes in glomerular podocytes. The clustering of nephrin induces its tyrosine phosphorylation, Nck recruitment, and sustained localized actin polymerization. Any one of three phosphorylated (p)YDXV motifs on nephrin is sufficient to recruit Nck through its Src homology 2 (SH2) domain and induce localized actin polymerization at these clusters. Similarly, Nck SH3 mutants in which only the second or third SH3 domain is functional can mediate nephrin-induced actin polymerization. However, combining such nephrin and Nck mutants attenuates actin polymerization at nephrin-Nck clusters. We propose that the multiple Nck SH2-binding motifs on nephrin and the multiple SH3 domains of Nck act cooperatively to recruit the high local concentration of effectors at sites of nephrin activation that is required to initiate and maintain actin polymerization in vivo. We also find that YDXV motifs in the Tir protein of enteropathogenic Escherichia coli and nephrin are functionally interchangeable, indicating that Tir reorganizes the actin cytoskeleton by molecular mimicry of nephrin-like signaling. Together, these data identify pYDXV/Nck signaling as a potent and portable mechanism for physiological and pathological actin regulation.
Blasutig
Ivan M
IM
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 1084-600 University Avenue, Toronto, Ontario M5G 1X5, Canada.
New
Laura A
LA
Thanabalasuriar
Ajitha
A
Dayarathna
Thamara K
TK
Goudreault
Marilyn
M
Quaggin
Susan E
SE
Li
Shawn S-C
SS
Gruenheid
Samantha
S
Jones
Nina
N
Pawson
Tony
T
D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001704:Biopolymers; D002478:Cells, Cultured / Q000378:metabolism / Q000648:ultrastructure; D003599:Cytoskeleton / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000737:chemistry / Q000502:physiology*; D010766:Phosphorylation; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D011956:Receptors, Cell Surface / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D018909:src Homology Domains
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D001704:Biopolymers; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C078332:Nck protein; D015513:Oncogene Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C109287:Tir protein, E coli; C113267:nephrin