Protein O-Glucosyltransferase 1 (POGLUT1) Promotes Mouse Gastrulation through Modification of the Apical Polarity Protein CRUMBS2

Autor: Kathryn V. Anderson, Robert S. Haltiwanger, Jan Wijnholds, Jeffrey D. Lee, C. Jane McGlade, Nitya Ramkumar, Nancy F. Silva-Gagliardi, Beth M. Harvey, Timothy H. Bestor, Heather L. Alcorn
Přispěvatelé: Netherlands Institute for Neuroscience (NIN)
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: PLoS Genetics, 11(10)
PLoS Genetics, Vol 11, Iss 10, p e1005551 (2015)
PLoS Genetics
PLoS Genetics, 11(10). Public Library of Science
ISSN: 1553-7404
Popis: 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.
Author Summary Post-translational addition of sugar chains is essential for normal activity of many secreted and transmembrane proteins and dozens of human genetic diseases are associated with congenital disorders of glycosylation. Protein O-glucosyltransferase 1 (POGLUT1), which is essential for early mouse development, catalyzes the addition of O-glucose to extracellular EGF repeats of proteins, including NOTCH1. Here we show that mouse POGLUT1 modifies NOTCH1 in vivo; however, the essential role of POGLUT1 in gastrulation is due to POGLUT1-dependent glycosylation of EGF repeats in the apical polarity protein CRUMBS2. In contrast to findings in Drosophila, where modification of Crumbs by POGLUT1 is not required, mouse POGLUT1 is required for the activity of CRUMBS2: the unmodified protein fails to localize to the apical membrane and the gastrulation defects of Poglut1 mutants are indistinguishable from those of Crumbs2 mutants. Human mutations in POGLUT1 cause Dowling-Degos Disease type 4; the hyperpigmentation associated with this autosomal dominant disease was previously attributed to altered Notch signaling, but our results suggest that this disease and other POGLUT1-associated phenotypes may be due to altered activity of CRUMBS proteins.
Databáze: OpenAIRE
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