Inhibition of Glycosphingolipid Biosynthesis Does Not Impair Growth or Morphogenesis of the Postimplantation Mouse Embryo

Abstract

Whole embryo culture (WEC) of organogenesis-stage mouse embryos was adapted for glycosphingolipid (GSL) metabolic studies to evaluate the hypothesis that de novo GSL biosynthesis is a prerequisite for growth and morphogenesis of the early postimplantation embryo. WEC supports the growth and development of postimplantation mouse embryos to stages that are indistinguishable from those achieved in vivo. N-Butyldeoxygalactonojirimycin (NB-DGJ) is an N-alkylated imino sugar that specifically inhibits biosynthesis of all glucosylceramide-based GSL5. NB-DGJ inhibited glucosylceramide and lactosylceramide biosynthesis nearly completely and inhibited ganglioside biosynthesis -~90%in both the embryo and visceral yolk sac. NB-DGJ also significantly reduced total ganglioside content in both the embryo and visceral yolk sac as estimated by the cholera toxin immunooverlaytechnique. A shift in expression from the structurally simple to the structurally complex gangliosides was also observed in NB-DGJ-treated embryos and yolk sacs. Despite causing major changes in GSL biosynthesis and composition, NB-DGJ had no effect on embryo viability, growth, or morphology. The findings suggest that de novo GSL biosynthesis may not be a prerequisite for the growth and morphogenesis of the organogenesis-stage mouse embryo. Key Words: Gangliosides-N-Butyldeoxygalactonojirimycin-Whole embryo culture-Organogenesis-GM1.

Substrate reduction reduces gangliosides in postnatal cerebrum-brainstem and cerebellum in GM1 gangliosidosis mice

“…Our findings indicate that inhibition of total ganglioside and GD3 biosynthesis did not affect the migration of granule cells from the EGL to the internal granular layer. These observations are consistent with previous findings that NB-DGJ-induced inhibition of ganglioside biosynthesis does not impair brain development in the organogenesis-stage mouse embryo (27). Hence, NB-DGJ may be an effective early intervention therapy for ganglioside storage diseases during critical stages of brain development.…”

“…This would be reasonable, because ceramide is a precursor for sphingomyelin synthesis. Moreover, it would be important to maintain low levels of ceramide because ceramide has been implicated in neural cell apoptosis (27,61). NB-DGJ treatment had no significant effect on the distribution of other major CNS neutral lipids.…”

“…These findings suggest that NB-DGJ treatment does not adversely affect myelinogenesis in the developing mouse CNS. Ceramide, sphingomyelin, and cerebroside are sphingolipids that could be influenced by NB-DGJ treatment (3,27,60). We previously found increases of whole brain ceramide and sphingomyelin in neonatal mice treated with a high NB-DGJ concentration (1,200 mg/kg) from p-2 to p-5 (3).…”

“…N B-DGJ, however, may be more suitable for treating neonates than N B-DNJ, because digestive abnormalities and weight loss do not occur with N B-DGJ treatment (3,17,26). Furthermore, we previously showed that N B-DGJ could reduce GSL and ganglioside biosynthesis by 90% in normal mouse embryos without impairing viability, growth, or morphogenesis (27). Our studies in embryonic and neonatal mice suggest that N B-DGJ may be an effective early intervention therapy for the gangliosidoses.…”

N -butyldeoxynojirimycin reduces growth and ganglioside content of experimental mouse brain tumours

“…A similar phenomenon was described previously in mouse embryos treated with N-butyldeoxygalactonojirimycin (NB-DGJ), a structural analogue of NB-DNJ, and is consistent with the substrate availability hypothesis of ganglioside biosynthesis Brigande et al, 1998). The shift in ganglioside distribution in the EPEN tumour likely results from the depletion of GM3 synthesis in the proliferating tumour cells.…”