Essential role of beta-1,4-galactosyltransferase 2 during medaka (Oryzias latipes) gastrulation

Abstract

Glycans are known to play important roles in vertebrate development; however, it is difficult to analyze in mammals because it takes place in utero. Therefore, we used medaka (Oryzias latipes) to clarify the roles of glycans during vertebrate development. beta-1,4-Galactosyltransferase is one of the key enzymes in the biosynthesis of the lactosamine structures that are commonly found on glycoproteins and glycolipids. Here, we show the essential role of beta4GalT2 during medaka development. Depletion of beta4GalT2 by morpholino antisense oligonucleotide injection resulted in significant morphological defects, such as shortening of the anterior-posterior axis, cyclopia, impaired somite segmentation, and head hypoplasia. In situ hybridization analyses revealed that the loss of beta4GalT2 led to defective anterior-posterior axis elongation during gastrulation without affecting organizer formation. Furthermore, a cell tracing experiment demonstrated that beta4GalT2 knockdown mainly affects mediolateral cell intercalation, which contributes to anterior-posterior axis elongation. A cell transplantation experiment indicated that glycans are produced by beta4GalT2 cell-autonomously during gastrulation. beta4GalT2 depletion also led to enhanced apoptosis; however, this does not account for the phenotypic abnormalities, as blockade of apoptosis failed to compensate for the beta4GalT2 depletion. Our data suggest that beta4GalT2 activity is cell-autonomously required in cells undergoing mediolateral cell intercalation, which drives extension movements during medaka gastrulation.

β1,4-Galactosyltransferases, Potential Modifiers of Stem Cell Pluripotency and Differentiation

“…Interestingly, in the mopholino treated embryos, laminin was hypo-galactosylated and hence could explain the decreased in ectodermal cell migration of [94]. β4Gal-T2: Tonoyama, et al showed that β4Gal-T2 was indispensable for mediolateral cell intercalation and thus extension movement during gastrulation [95]. The specific substrates for β4Gal-T2 activity in glycoproteins responsible for these ef-fects are currently not known but has been speculated to be related with N-glycosylated FGF receptor signaling.…”

Localization of Golgi-resident glycosyltransferases

“…Mislocalization of glycosyltransferases within the Golgi can have profound effects on glycan synthesis and in turn on the normal physiology of cells. The cell biological, developmental, and physiological significance of the action of glycosyltransferases is highlighted by the consequences of deletion or knock-down of members of this protein family, which results in developmental anomalies as well as in congenital defects in glycosylation (CDG) in humans [1,[16][17][18][19][20][21][22][23].…”

Transcriptomic landscape of the primitive streak

“…5; data not shown) analyses revealed that a group of at least 24 glycosyltransferases (see Table S6 in the supplementary material) exhibits either a DrV (15) or VrD (9) profile. Sugar epitope modification of receptor and extracellular molecules has been reported to modulate signaling activities in many other systems (Haecker et al, 2008;Machingo et al, 2006;Tonoyama et al, 2009). Given that several major signaling pathways are key components in the regulation of positional identities in the streak, it is not surprising that we found these 24 enzymes exhibiting differential levels of expression in the streak, representing both early and late steps of O-linked and N-linked glycosyl modification.…”