Pofut1 is required for the proper localization of the Notch receptor during mouse development.
Protein O-fucosyltransferase 1 (Pofut1), which catalyzes the addition of O-linked fucose to the EGF domains of the Notch receptor, is indispensable for Notch signaling activation. However, the mechanism of action of Pofut1 in mice is still unclear. Mouse embryos lacking Pofut1 shows defects in valve formation and trabeculation in the cardiovascular system, which are almost identical abnormalities to those of the RBP-Jk mutants. In our current study, we have examined the epistatic relationship between the functions of Pofut1 and activated-Notch1 (NICD1) by taking advantage of the fact that forced expression of NICD1 results in myocardial defects. These defects were still evident in NICD1-expressing embryos irrespective of the presence or absence of Pofut1, which indicates that Pofut1 is required for Notch signaling upstream of NICD1. We further found that Pofut1-null cells do not possess normally localized Notch1 receptors, which may results in their lack of interaction with the Dll1 ligand in the presomitic mesoderm where Notch signaling plays a pivotal role. We propose that altered trafficking pathways may account for the abnormal accumulation of the Notch1 receptor in the endoplasmic reticulum in Pofut1-null mouse embryos.
Okamura
Yoshiaki
Y
Department of Genetics, SOKENDAI, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.
Saga
Yumiko
Y
D000818:Animals; D002135:Calcium-Binding Proteins; D018376:Cardiovascular Abnormalities / Q000196:embryology* / Q000378:metabolism; D022461:Caveolins / Q000378:metabolism; D004705:Endocytosis; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005647:Fucosyltransferases / Q000235:genetics / Q000502:physiology*; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D002135:Calcium-Binding Proteins; D022461:Caveolins; C512925:Dlk1 protein, mouse; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D036341:Intercellular Signaling Peptides and Proteins; C497762:Notch1 protein, mouse; D051881:Receptor, Notch1; D005647:Fucosyltransferases; C105148:polypeptide fucosyltransferase