Nck adaptor proteins link nephrin to the actin cytoskeleton of kidney podocytes.
The glomerular filtration barrier in the kidney is formed in part by a specialized intercellular junction known as the slit diaphragm, which connects adjacent actin-based foot processes of kidney epithelial cells (podocytes). Mutations affecting a number of slit diaphragm proteins, including nephrin (encoded by NPHS1), lead to renal disease owing to disruption of the filtration barrier and rearrangement of the actin cytoskeleton, although the molecular basis for this is unclear. Here we show that nephrin selectively binds the Src homology 2 (SH2)/SH3 domain-containing Nck adaptor proteins, which in turn control the podocyte cytoskeleton in vivo. The cytoplasmic tail of nephrin has multiple YDxV sites that form preferred binding motifs for the Nck SH2 domain once phosphorylated by Src-family kinases. We show that this Nck-nephrin interaction is required for nephrin-dependent actin reorganization. Selective deletion of Nck from podocytes of transgenic mice results in defects in the formation of foot processes and in congenital nephrotic syndrome. Together, these findings identify a physiological signalling pathway in which nephrin is linked through phosphotyrosine-based interactions to Nck adaptors, and thus to the underlying actin cytoskeleton in podocytes. Simple and widely expressed SH2/SH3 adaptor proteins can therefore direct the formation of a specialized cellular morphology in vivo.
Jones
Nina
N
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada.
Blasutig
Ivan M
IM
Eremina
Vera
V
Ruston
Julie M
JM
Bladt
Friedhelm
F
Li
Hongping
H
Huang
Haiming
H
Larose
Louise
L
Li
Shawn S-C
SS
Takano
Tomoko
T
Quaggin
Susan E
SE
Pawson
Tony
T
D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D003599:Cytoskeleton / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology* / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation / Q000235:genetics; D009404:Nephrotic Syndrome / Q000151:congenital / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015513:Oncogene Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D018909:src Homology Domains
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D008565:Membrane Proteins; C078332:Nck protein; D015513:Oncogene Proteins; C113267:nephrin; D019000:Phosphotyrosine