Heparan Sulfate Proteoglycans function as receptors for the R-spondins, a family of growth factors that amplify the strength of WNT signaling during development and in adult stem cells.
Valerie PI Vidal, Fariba Jian-Motamedi ... Andreas Schedl
In the developing kidney, secreted molecules of the R-spondin family control progenitor cell proliferation and nephron formation by permitting WNT/β-catenin signalling.
R-spondins 2 and 3 can potentiate WNT signaling in the absence of LGRs through interactions with ZNRF3/RNF43 E3 ubiquitin ligases and heparan sulfate proteoglycans, defining two alternative modes of R-spondin-mediated signaling.
R-spondin3 global haplo-insufficiency or its deletion in pre-osteoblasts lead to gain of bone mass in the appendicular skeleton with no or opposite phenotype in the axial skeleton.
A systematic genetic analysis comprising seven genome-wide screens in haploid human cells uncovered new regulatory mechanisms at most levels in the WNT signaling pathway.
Two cancer related proteins, tyrosine phosphatase PTPRK and ubiquitin ligase ZNRF3, interact to downregulate Wnt receptors, thereby regulating Spemann organizer function during Xenopus development.