Molecular evolution and expression of zebrafish St8SiaIII, an alpha‐2,8‐sialyltransferase involved in myotome development

Abstract

Enzymes of the St8Sia family, a subgroup of the glycosyltransferases, mediate the transfer of sialic acid to glycoproteins or glycolipids. Here, we describe the cloning of the zebrafish St8SiaIII gene and study its developmental activity. A conserved synteny relationship among vertebrate chromosome regions containing St8SiaIII loci underscores an ancient duplication of this gene in the teleost fish lineage and a specific secondary loss of one paralog in the zebrafish. The single zebrafish St8SiaIII enzyme, which is expected to function as an oligosialyltransferase, lacks maternal activity, is weakly expressed during nervous system development, and shows a highly dynamic expression pattern in somites and somitederived structures. Morpholino knock-down of St8SiaIII leads to anomalous somite morphologies, including defects in segment boundary formation and myotendious-junction integrity. These phenotypes hint for a basic activity of zebrafish St8SiaIII during segmentation and somite formation, providing novel evidence for a non-neuronal function of sialyltransferases during vertebrate development. Developmental Dynamics 237:808 -818, 2008.

Molecular cloning and characterization of the expression pattern of the zebrafish α2, 8-sialyltransferases (ST8Sia) in the developing nervous system

“…At 5 days, the ST8Sia V gene expression is very strong in brain (non ventricular zone) and in all cranial ganglia (M, P). cg cranial ganglia, cst corpuscle of Stannius, dc diencephalons, ep epiphysis, fb forebrain, hb hindbrain, hyth hypothalamus, mb midbrain, ntg nucleus in tegmentum, op olfactory placodes, opt optic tectum, retina gcl retina ganglion cell layer, retina icl retina inner cell layer, sc spinal cord, scn spinal cord neurons, tc telencephalon, tg tegmentum, tgg trigeminal ganglia, vz ventricular zone experiment in the developing zebrafish embryo lacks expression of the zebrafish ST8Sia III gene until 24 hpf, which is in contrast to another recent study showing early expression of the ST8Sia III gene along the anteriorposterior axis of the developing embryo at the end of gastrulation (12 hpf) [46] and correlates with exact mRNA quantification by real time PCR data (Chang et al 2008, this issue). Late induction of the ST8Sia III gene is also in agreement with the fact that oligosialylated glycolipids are exclusively detected in embryonic tissues from 24 hpf onwards (Chang et al 2008, this issue).…”

Systemic Fluorescence Imaging of Zebrafish Glycans with Bioorthogonal Chemistry

“…[27] Also notable was the bright labeling along the intermyotomal boundaries as well as on the surface of muscle fiber cells in the myotomes, which also express St8SiaIII ( Figure 3F). [26] In addition to these structures that we had expected to be sialylated, we observed several novel sialylation patterns. A ventral view of the embryo revealed sialylation of the optic nerve ( Figure 3G) as well as at the exterior of the developing mouth ( Figure 3H); posterior to the mouth, we observed a tubular sialylation pattern from a lateral view ( Figure 3I).…”

“…The BCNSia dependence of labeling was particularly apparent in higher-magnification images of the head acquired from the lateral, ventral, dorsal, and rostral views, as well as in a lateral view of the tail ( Figure 3C, Movies S1-S5, and Figure S6). In the eyes, both the retina and the surfaces of the onion-shaped fiber cells that make up the lens, which is known to heavily express the sialyltransferase St8SiaIII during development, [26] were sialylated ( Figure 3D). Analysis of the labeling pattern within the lens showed that the fluorescence was more concentrated at intercellular contacts between three or more cells than at contacts between two cells ( Figure 3D″).…”

Identification and Biochemical Characterization of Two Functional CMP-Sialic Acid Synthetases in Danio rerio

“…The expression of the sialyltransferases st8sia1 and st8sia5 (38) as well as of polysialyltransferase st8sia2 starts around 10 hpf in the developing nervous system (7,39). The oligosialyltransferase st8sia3 shows a highly dynamic expression in somites and somite-derived structures (8). It is also detected in the developing nervous system (38) corresponding to drecmas1 expression in early embryonic stages.…”

“…ST8Sia3, the third zebrafish sialyltransferase analyzed to date, catalyzes the formation of oligosialic acid chains. Downregulation of ST8Sia3 entails anomalous somite morphology, which shows that Sia also play a role in non-neuronal development (8).…”