Glypican (GPC)-3 inhibits cell proliferation and regulates cell survival during development. This action is demonstrated by GPC3 loss-of-function mutations in humans and mice. Here, we show that the GPC3 core protein is processed by a furinlike convertase. This processing is essential for GPC3 modulating Wnt signaling and cell survival in vitro and for supporting embryonic cell movements in zebrafish. The processed GPC3 core protein is necessary and sufficient for the cell-specific induction of apoptosis, but in vitro effects on canonical and noncanonical Wnt signaling additionally require substitution of the core protein with heparan sulfate. Wnt 5A physically associates only with processed GPC3, and only a form of GPC3 that can be processed by a convertase is able to rescue epiboly and convergence/extension movements in GPC3 morphant embryos. Our data imply that the Simpson–Golabi–Behmel syndrome may in part result from a loss of GPC3 controls on Wnt signaling, and suggest that this function requires the cooperation of both the protein and the heparan sulfate moieties of the proteoglycan.
Processing by proprotein convertases is required for glypican-3 modulation of cell survival, Wnt signaling, and gastrulation movements
Abbreviations used in this paper: BFA, brefeldin A; CRD, cysteine-rich domain; GPC, glypican; GPI, glycosylphosphatidylinositol; hpf, hours post fertilization; HS, heparan sulfate; HSPG, heparan sulfate proteoglycan; JNK, c-Jun NH2-terminal protein kinase; PC, proprotein convertase; SGBS, Simpson-Golabi-Behmel syndrome.
Bart De Cat, Sin-Ya Muyldermans, Christien Coomans, Gisèle Degeest, Bernadette Vanderschueren, John Creemers, Frédéric Biemar, Bernard Peers, Guido David; Processing by proprotein convertases is required for glypican-3 modulation of cell survival, Wnt signaling, and gastrulation movements . J Cell Biol 10 November 2003; 163 (3): 625–635. doi: https://doi.org/10.1083/jcb.200302152
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