Sprouty1 haploinsufficiency prevents renal agenesis in a model of Fraser syndrome.
Deficiency of the extracellular matrix molecule FRAS1, normally expressed by the ureteric bud, leads to bilateral renal agenesis in humans with Fraser syndrome and blebbed (Fras1(bl/bl)) mice. The metanephric mesenchyme of these mutants fails to express sufficient Gdnf, which activates receptor tyrosine kinase (RTK) signalling, contributing to the phenotype. To determine whether modulating RTK signalling may overcome the abnormal nephrogenesis characteristic of Fraser syndrome, we introduced a single null Sprouty1 allele into Fras1(bl/bl) mice, thereby reducing the ureteric bud's expression of this anti-branching molecule and antagonist of RTK signalling. This prevented renal agenesis in Fras1(bl/bl) mice, permitting kidney development and postnatal survival. We found that fibroblast growth factor (FGF) signalling contributed to this genetic rescue, and exogenous FGF10 rescued defects in Fras1(bl/bl) rudiments in vitro. Whereas wild-type metanephroi expressed FRAS1 and the related proteins FREM1 and FREM2, FRAS1 was absent and the other proteins were downregulated in rescued kidneys, consistent with a reciprocally stabilized FRAS1/FREM1/FREM2 complex. In addition to contributing to knowledge regarding events during nephrogenesis, the demonstrated rescue of renal agenesis in a model of a human genetic disease raises the possibility that enhancing growth factor signaling might be a therapeutic approach to ameliorate this devastating malformation.
Molecular Medicine Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, United Kingdom.
Jolanta E
JE
Pitera
Adrian S
AS
Woolf
M Albert
MA
Basson
Peter J
PJ
Scambler
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D004195:Disease Models, Animal; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D058497:Fraser Syndrome / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D057895:Haploinsufficiency; D006801:Humans; D007668:Kidney / Q000002:abnormalities* / Q000196:embryology / Q000378:metabolism; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D010750:Phosphoproteins / Q000172:deficiency* / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction
D048868:Adaptor Proteins, Signal Transducing; D016326:Extracellular Matrix Proteins; C482018:Fras1 protein, mouse; C492585:Frem1 protein, mouse; C504802:Frem2 protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; C425468:Spry1 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases