In vivo and in vitro expression of rat galactose-1-phosphate uridyltransferase (GALT) in the developing central and peripheral nervous system.

Abstract

Galactose-1-phosphate uridyltransferase (GALT) is a key enzyme in the metabolism of galactose. GALT activates the galactose-glucose interconversion and enables the synthesis of glucose-1-phosphate and UDP-galactose (UDP-Gal). UDP-Gal is the galactosyl donor for the incorporation of galactose into complex oligosaccharides, glycoproteins and glycolipids. The expression of GALT was characterized both in vivo and in vitro during late embryonic and postnatal development of the brain and peripheral nerve of the rat. Assays of GALT mRNA and protein showed that it is weakly expressed during late embryonic development with a second peak of expression concomitant with myelinogenesis. GALT was prominently expressed in myelinating Schwann cells in a rat dorsal root ganglia culture system. GALT deficiency in humans results in galactosemia, a disease characterized by long-term intellectual impairment, and probably dysmyelination. The developmentally regulated pattern of GALT expression during maturation of the nervous system may provide a molecular basis for these neurological complications which seriously compromise the outcome of many galactosemic patients.