IN-VIVO AND IN-VITRO EXPRESSION OF RAT GALACTOSE-1-PHOSPHATE URIDYLTRANSFERASE (GALT) IN THE DEVELOPING CENTRAL AND PERIPHERAL NERVOUS-SYSTEM

Galactose-1-phosphate uridyltransferase (GALT) is a key enzyme in the metabolism of galactose. GALT activates the galactose-glucose intercon version and enables the synthesis of glucose-1-phosphate and UDP-galac tose (UDP-Gal). UDP-Gal is the galactosyl donor for the incorporation of galactose into complex oligosaccharides, glycoproteins and glycolip ids. The expression of GALT was characterized both in vivo and in vitr o during rate embryonic and postnatal development of the brain and per ipheral 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 prominen tly expressed in myelinating Schwann cells in a rat dorsal root gangli a culture system, GALT deficiency in humans results in galactosemia, a disease characterized by long-term intellectual impairment, and proba bly dysmyelination. The developmentally regulated pattern of GALT expr ession during maturation of the nervous system may provide a molecular basis for these neurological complications which seriously compromise the outcome of many galactosemic patients.