Title :
Protein O-Glucosyltransferase 1 (
POGLUT1 ) Promotes Mouse Gastrulation through Modification of the Apical Polarity Protein CRUMBS2
Abstract :
- Crumbs family proteins are apical transmembrane proteins with ancient roles in cell polarity
- Mouse Crumbs2 mutants arrest at midgestation with abnormal neural plate morphology and a deficit of mesoderm caused by defects in gastrulation
- We identified an ENU-induced mutation, wsnp, that phenocopies the Crumbs2 null phenotype
- We show that wsnp is a null allele of Protein O-glucosyltransferase 1 ( Poglut1 ), which encodes an enzyme previously shown to add O-glucose to EGF repeats in the extracellular domain of Drosophila and mammalian Notch, but the role of POGLUT1 in mammalian gastrulation has not been investigated
- As predicted, we find that POGLUT1 is essential for Notch signaling in the early mouse embryo
- However, the loss of mouse POGLUT1 causes an earlier and more dramatic phenotype than does the loss of activity of the Notch pathway, indicating that POGLUT1 has additional biologically relevant substrates
- Using mass spectrometry, we show that POGLUT1 modifies EGF repeats in the extracellular domain of full-length mouse CRUMBS2
- CRUMBS2 that lacks the O-glucose modification fails to be enriched on the apical plasma membrane and instead accumulates in the endoplasmic reticulum
- The data demonstrate that CRUMBS2 is the target of POGLUT1 for the gastrulation epithelial-to-mesenchymal transitions ( EMT ) and that all activity of CRUMBS2 depends on modification by POGLUT1
- Mutations in human POGLUT1 cause Dowling-Degos Disease , POGLUT1 is overexpressed in a variety of tumor cells, and mutations in the EGF repeats of human CRUMBS proteins are associated with human congenital nephrosis, retinitis pigmentosa and retinal degeneration, suggesting that O-glucosylation of CRUMBS proteins has broad roles in human health