Developmental patterns of ceramide glucosyltransferase (GlcT-1) expression in the mouse: in situ hybridization using DIG-labeled RNA probes.

Glycosphingolipids (GSLs) play significant roles in a variety of cell membrane events, including cellular interactions, signaling, and trafficking. Ceramide glucosyltransferase (glucosylceramide synthase, GlcT-1, EC 2.4.1.80) catalyzes the initial step in GSL synthesis, the transfer of glucose from UDP-glucose to ceramide. The reaction product of glucosylceramide serves as a core structure for over 400 species of GSLs. The enzyme is a key regulatory factor controlling intracellular levels of ceramide and GSLs. Appearance and differential distribution of GlcT-1 mRNA during mice postimplantation embryogenesis [embryonic (E) days; E9, E11, E13, E15] were investigated by in situ hybridization with digoxigenin-labeled RNA probes, coupled with alkaline phosphatase detection. On E9, tissues of the mesencephalon, myelecephalon, diencephalons, and telencephalon expressed GlcT-1. On E11, it was expressed to a detectable extent in various tissues including mesencephalon, myelecephalon, diencephalon, telencephalon, nose, lung, liver, vertebra, tail, spinal cord, and tongue. The expression patterns of E13 were similar to those of E11, except that the heart and stomach became positive. On E15, a specific signal for GlcT-1 was detected in all organs of the embryo. These results provide the first evidence that GlcT-1 is differentially expressed during postimplantation embryogenesis.