Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two independent approaches were employed to explore the potential role of endogenous glucosylceramide or a closely related glucosphingolipid in mediating the cellular proliferation of Madin-Darby canine kidney cells. First, cultured cells were depleted of glucosphingolipids by exposure to a glucosylceramide synthase inhibitor, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol. This agent markedly inhibited cell growth and DNA synthesis in a time- and concentration-dependent manner. Second, cells were grown in the presence of conduritol B epoxide, an inhibitor of glucosylceramide beta-D-glucosidase. Exposure of cells to this inhibitor resulted in the time-dependent accumulation of glucosylceramide with a corresponding increase in cellular proliferation. Alterations in protein kinase C activity were evaluated as a potential mechanism for these effects on growth. Both membrane- and cytosol-associated protein kinase C (PKC) activity declined under conditions of glucosylceramide synthase inhibition and increased under conditions of beta-glucosidase inhibition. The changes in PKC activity were evident after DEAE-cellulose purification. Diacylglycerol levels increased in response to both glucosylceramide synthase and beta-glucosidase inhibition. Ceramide and sphingosine levels changed only in the presence of D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, increasing due to lack of conversion to glucosylceramide. However, the elevation in endogenous sphingosine was probably insufficient to account for the decrease in PKC, considering the high level of diacylglycerol in the cells. These data demonstrate an association between glucosylceramide levels, PKC activity, and cell growth.
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PMID:Modulation of renal epithelial cell growth by glucosylceramide. Association with protein kinase C, sphingosine, and diacylglycerol. 174 91

To clarify the metabolic bases of characteristic increases in the concentrations of glucosylceramide (CMH) and GM3 in peroxisome-defective mutant Chinese hamster ovary (CHO) cells (Z65), we measured the ceramide glucosyltransferase (CGT) and beta-glucosidase activities in Z65 and CHO-K1 cells, and found that the former enzyme was responsible for the accumulation of CMH in Z65 cells. Inhibition of CGT by D,L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) caused a marked reduction in a incorporation of [3-14C]serine to CMH in both CHO-K1 and Z65 cells, but resulted in the accumulation of ceramide in Z65 cells in a concentration higher than that in CHO-K1 cells. Then, we cloned the cDNA encoding CGT from CHO-K1 cells, which exhibited sequence homology with the human gene product (98.7%). Northern blot analysis of CGT revealed increased expression of it in Z65 cells compared with that in CHO-K1 cells, which probably caused the simultaneous increase in GM3. With an immunohistochemical procedure, GM3 was found to be more strongly expressed in the cell membrane of Z65 cells than in CHO-K1 cells.
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PMID:Molecular cloning of Chinese hamster ceramide glucosyltransferase and its enhanced expression in peroxisome-defective mutant Z65 cells. 1213 66

Gaucher disease is a lysosomal glycolipid storage disorder characterized by defects in acid-beta-glucosidase (GlcCerase), the enzyme responsible for the catabolism of glucosylceramide. We recently demonstrated that isofagomine (IFG), an iminosugar that binds to the active site of GlcCerase, enhances the folding, transport and activity of the N370S mutant form of GlcCerase. In this study we compared the effects of IFG on a number of other glucosidases and glucosyltransferases. We report that IFG has little or no inhibitory activity towards intestinal disaccharidase enzymes, ER alpha-glucosidase II or glucosylceramide synthase at concentrations previously shown to enhance N370S GlcCerase folding and trafficking in Gaucher fibroblasts. Furthermore, treatment of wild type fibroblasts with high doses of IFG did not alter the processing of newly synthesized N-linked oligosaccharides. These findings support further evaluation of IFG as a potential therapeutic agent in the treatment of some forms of Gaucher disease.
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PMID:Selective action of the iminosugar isofagomine, a pharmacological chaperone for mutant forms of acid-beta-glucosidase. 1721 20

Epidermal differentiation results in the formation of the extracellular lipid barrier in the stratum corneum, which mainly consists of ceramides, free fatty acids, and cholesterol. Differentiating keratinocytes of the stratum granulosum synthesize a series of complex long-chain ceramides and glucosylceramides with different chain lengths and hydroxylation patterns at intracellular membranes of the secretory pathway. Formation of complex extracellular ceramides parallels the transition of keratinocytes from the stratum granulosum to the stratum corneum, where their precursors, complex glucosylceramides and sphingomyelin, are secreted and exposed to extracellular lysosomal lipid hydrolases. Submerged cultures used so far showed a reduced ceramide content compared to the native epidermis or the air-exposed, organotypic culture system. In order to investigate the sphingolipid metabolism during keratinocyte differentiation, we optimized a simple cell culture system to generate the major barrier sphingolipids. This optimized model is based on the chemically well-defined serum-free MCDB medium. At low calcium ion concentrations (0.1mM), keratinocytes proliferate and synthesize mainly Cer(NS) and a small amount of Cer(NP). Supplementation of the MCDB cell culture medium with calcium ions (1.1mM) and 10 microM linoleic acid triggered differentiation of keratinocytes and synthesis of a complex pattern of free and covalently bound ceramides as found in native epidermis or air-exposed organotypic cultures, though at a reduced level. The mRNA levels of the differentiation markers keratin 10 and profilaggrin increased, as well as those of ceramide glucosyltransferase and glucosylceramide-beta-glucosidase. The described culture system was thus suitable for biochemical studies of the sphingolipid metabolism during keratinocyte differentiation. The addition of serum or vitamin A to the medium resulted in a decrease in ceramide and glucosylceramide content. Lowering the medium pH to 6, while maintained cell viability, led to an increase in the processing of probarrier lipids glucosylceramide and sphingomyelin to free ceramides and protein-bound ceramide Cer(OS).
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PMID:Optimization of submerged keratinocyte cultures for the synthesis of barrier ceramides. 1771 27