Early lethality of β-1,4-galactosyltransferase V-mutant mice by growth retardation

The β-1,4-galactosyltransferase (β-1,4-GalT) V whose human and mouse genes were cloned by us has been suggested to be involved in the biosynthesis of N-glycans and O-glycans, and lactosylceramide. To determine its biological function, β-1,4-GalT V (B4galt5) mutant mice obtained by a gene trap method were analyzed. Analysis of pre- and post-implantation embryos revealed that the B4galt5−/− mice die by E10.5 while B4galt5+/− mice were born and grown normally. Histological study showed that most tissues are formed in B4galt5−/− embryos but their appearance at E10.5 is close to that of B4galt5+/− embryos at E9.0-9.5. The results indicate that the growth is delayed by one to one and half day in B4galt5−/− embryos when compared to B4galt5+/− embryos, which results in early death of the embryos by E10.5, probably due to hematopoietic and/or placental defects.