Proximal promoter region is sufficient to regulate tissue-specific expression of UDP-galactose: Ceramide galactosyltransferase gene

Abstract

UDP-galactose:ceramide galactosyltransferase (CGT) is the enzyme which catalyzes the final step of the biosynthesis of galactocerebroside (GalC), the most abundant glycolipid in myelin. We identified regulatory elements which are related to the tissue-specific expression of the mouse CGT gene by promoter assay using chimeric CGT-luciferase constructs. By comparing promoter activity in oligodendroglial CG4 cells and NIH3T3 fibroblasts, only a few hundred base pairs spanning from -309 to -98 were shown to be necessary for the tissue-specific activity of CGT promoter. A negative regulatory element was found in a more distal region, from -709 to -527, and it also worked in tissue-specific manner. Sequence analysis suggests that several known elements found commonly in myelin-related genes may explain these tissue-specific regulations of the transcriptional activity.

Implications of galactocerebrosidase and galactosylcerebroside metabolism in cancer cells

“…14 Second, an increased activity of the GalCS would also induce feedback inhibition of itself and the enzymes in series as well as activation of the GalCer degradation pathway. 31 This would even suggest an increased GALC activity. There are some findings, however, that support the induction of GalCS in cancer cells: in experimental preclinical trials involving breast and epidermoid cancer cell lines treated with adriamycin, vinca alkaloids and etoposide, the utilisation of ceramide has been induced via glycosylation reactions.…”

“…GalCer is formed out of ceramide and UDP-b-galactose as substrates of the enzyme galactosylcerebroside synthase (GalCS, 2-hydroxyacylsphingosine 1-b-galactosyltransferase, EC 2.4.1.45). 13,31 There are several aspects that contradict an overproduction as a cause of increased GalCer presence upon cellular surfaces. First, there is evidence for decreased GALC gene transcription in HNSCC.…”

Functional central nervous system myelin repair in an adult mouse model of demyelination caused by proteolipid protein overexpression

“…CG4 cells were plated on plastic 24‐well plates in our glial defined medium (GDM) to maintain the OLP stage (Yonemasu et al, 1998). One day prior to transplantation, cells were labeled with fast blue.…”

“…These rats develop seizures and succumb at approximately 25 days of age (Csiza and De Lahunta, 1979). In dysmyelinating mutants, an arrest in oligodendrocyte (OL) maturation prevents their terminal differentiation, resulting in dysmyelination (Kumar et al, 1988, 1990). Nonetheless, in cell culture, these mutant OL progenitors (OLP) show lineage progression (Espinosa de los Monteros et al, 1990), indicating that the genetic blueprint of OL progenitors is complemented by extrinsic regulators that determine their survival, maturation, and function.…”

“…In the wild‐type (Wt) rat brain, the iron carrier glycoprotein transferrin (Tf) is expressed solely in OL and choroid plexus (for review see Espinosa de los Monteros et al, 1988, 1993). By using OL in culture, we demonstrated that OL synthesize and secrete Tf (Conner and Fine, 1986; Connor et al, 1987; Espinosa et al, 1998; Espinosa de los Monteros et al, 1990). Tf is a fundamental constituent of most chemically defined media used as a supplement to culture mammalian neural and nonneural cells (Barnes and Sato, 1980), including developing OL (Espinosa de los Monteros et al, 1988, 1997; Espinosa‐Jeffrey et al, 2002) but not mature OL (Espinosa de los Monteros et al, 1988).…”