RESUMO

Cell surface of eukaryotic cells is covered with a wide variety of sialylated molecules involved in diverse biological processes and taking part in cell-cell interactions. Although the physiological relevance of these sialylated glycoconjugates in vertebrates begins to be deciphered, the origin and evolution of the genetic machinery implicated in their biosynthetic pathway are poorly understood. Among the variety of actors involved in the sialylation machinery, sialyltransferases are key enzymes for the biosynthesis of sialylated molecules. This review focus on ß-galactoside α2,3/6-sialyltransferases belonging to the ST3Gal and ST6Gal families. We propose here an outline of the evolutionary history of these two major ST families. Comparative genomics, molecular phylogeny and structural bioinformatics provided insights into the functional innovations in sialic acid metabolism and enabled to explore how ST-gene function evolved in vertebrates.

Assuntos

Sialiltransferases/metabolismo , Vertebrados/metabolismo , Animais , Ácido N-Acetilneuramínico/metabolismo , Filogenia , Sialiltransferases/classificação , Sialiltransferases/genética , Vertebrados/genética

RESUMO

Gangliosides are a subfamily of complex glycosphingolipids (GSLs) with important roles in many biological processes. In this study, we report the cDNA cloning, functional characterization, and the spatial and temporal expression of Xlcgt and Xlgd3 synthase during Xenopus laevis development. Xlcgt was expressed both maternally and zigotically persisting at least until stage 35. Maternal Xlgd3 synthase mRNA could not be detected and showed a steady-state expression from gastrula to late tailbud stage. Xlcgt is mainly present in involuted paraxial mesoderm, neural folds, and their derivatives. Xlgd3 synthase transcripts were detected in the dorsal blastoporal lip, in the presumptive neuroectoderm, and later in the head region, branchial arches, otic and optic primordia. We determined the effect of glycosphingolipid depletion with 1-phenyl-2-palmitoyl-3-morpholino-1-propanol (PPMP) in mesodermal layer. PPMP-injected embryos showed altered expression domains in the mesodermal markers. Our results suggest that GSL are involved in convergent-extension movements during early development in Xenopus.

Assuntos

Enzimas/metabolismo , Glicoesfingolipídeos/biossíntese , Proteínas de Xenopus/metabolismo , Xenopus laevis/metabolismo , Sequência de Aminoácidos , Animais , Western Blotting , Clonagem Molecular , DNA Complementar/química , DNA Complementar/genética , Embrião não Mamífero/metabolismo , Ativação Enzimática/efeitos dos fármacos , Enzimas/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Glucosiltransferases/classificação , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Hibridização In Situ , Microscopia Confocal , Dados de Sequência Molecular , Morfolinas/farmacologia , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Sialiltransferases/classificação , Sialiltransferases/genética , Sialiltransferases/metabolismo , Esfingolipídeos/farmacologia , Proteínas de Xenopus/genética , Xenopus laevis/genética