Xenopus laevis as a model to study CDG caused by SLC35A3-transporter mutations

BREDESTON LM, HAEL A, FAVAROLO MB, AYBAR M

Buenos Aires

Simposio; 2do Simposio de Latino América de Desordenes Congenitos de Glicosilacion; 2014

Sociedad Latinoamericana de Glicobiologia A.C

Nucleotide-sugar transporters (NST, SLC35 family) control the flux of activated sugar to the secretion pathway where glyconjugate biosynthesis take place by specific transferases. SLC35A3 is a Golgi apparatus NST-member, specific for UDP-GlcNAc. Mutations in SLC35A3 cause vertebral complex malformation in bovines (Thomsen et al., 2006 Genome Res. 16, 97-105) and autism spectrum disorder, epilepsy and arthrogryposis in humans (Edvarson, 2013, J. Med. Genet. 50, 733-39) by an unknown molecular mechanism.  The aims of the work is to use Xenopus laevis as a model to study the role of SLC35A3 on embryonic development. Results shown: 1) XtSLC35A3 complement the yeast  mutant Kl3, confirming its specificity for UDP-GlcNac. Fusion of GFP to the C-terminal of XtSLC35A3 does not affect transport activity and can be used as an expression indicator. 2) The yeast system was used to identified a mutant that impairs activity but not expression (E47C). 3) RT-PCR studies of SLC35A3 using X. laevis embryos show expression between stages 28 and 35. Localization of SLC35A3 transcripts in X. laevis embryos from stages 18 to 33, by whole mount in situ hybridization, showed specific labelling of the notochord from stage 28 to 33. 4) Overexpression of wild type SLC35A3 affected mesoderm, the embryonic sheet from which notochord is derived, suggesting that precise levels of transporter expression are necessary for the normal development of the mesoderm. Working in progress, using morpholino silencing techniques  can help to understand the mammalian phenotypes described previously. Acknowledgment: supported by CIUNT, CONICET and ANPCYT-FONCYT.