R-Spondin 3 (RSPO3) protein belongs to the R-spondin family comprizing four structurally-related, secreted ligands (RSPO 1-4)1. All contain furin-like and thrombospondin structural domains. R-spondins are activators of the canonical Wnt signaling pathway. Receptors include the leucine-rich repeat-containing G-protein coupled receptors (LGR) 4-62. In the colon, R-spondin 3 promotes stem cell recovery and epithelial repair via induction of Wnt.
An R-spondin, such as R-spondin 3, is an essential component of Wnt 3a, R-spondin-3 (or 1,2), Noggin (WRN) media used widely in propagation of intestinal organoids2. There is a drive towards improved reproducibility in stem cell and organoid culture. Conditioned media (spent media from cells that secrete growth factors such as Wnt and R-spondin, along with several other factors and waste products) is both challenging to manufacture consistently and conveniently, and a source of variability between labs3.