dolichols and Disease-Models--Animal

Adult neuronal ceroid lipofuscinosis (NCL), also called Kufs' disease, is clinically distinct from the other NCLs. It is a rare condition which is difficult to diagnose. More than 50% of the reported cases of Kufs' disease are not adult NCL and correspond very likely to a heterogeneous spectrum of lipidoses. Various clinical and genetic phenotypes of adult NCL may be recognized, one featuring a progressive myoclonus epilepsy. It is important to stress that in contradistinction with the juvenile and protracted juvenile NCL, there is no pigmentary degeneration of the retina. Adult NCL is an autosomal recessive condition but two families have an autosomal dominant inheritance. The diagnosis of adult NCL may be suggested by a careful evaluation of skin, rectal or brain biopsies with the electron microscope but the diagnosis is fraught with many hazards. The pathogenetic defect lies probably in the intracellular processing of lysosomal and perhaps of Golgi membranes. The recent discovery of subunit c of mitochondrial adenosine triphosphate synthase in the stored cytosomes represents certainly an interesting prospect for future developments.

Topics: Adolescent; Adult; Animals; Biopsy; Brain; Diagnosis, Differential; Disease Models, Animal; Dog Diseases; Dogs; Dolichols; Epilepsies, Myoclonic; Humans; Infant; Intracellular Membranes; Lipidoses; Lipids; Neuronal Ceroid-Lipofuscinoses; Neurons; Pigments, Biological; Retina; Skin

Elevated (4 to 7-fold) levels of urinary dolichol and coenzyme Q and substantially longer chain lengths for urinary dolichols have been reported in Smith-Lemli-Opitz Syndrome (SLOS) patients, compared to normal subjects. We investigated the possibility of similar alterations in hepatic, nonsterol isoprenoids in a well-established rat model of SLOS. In this model, the ratio of 7-dehydrocholesterol (7DHC) to cholesterol (Chol) in serum approached 15:1; however, total sterol mass in serum decreased by >80 %. Livers from treated rats had 7DHC/Chol ratios of ~32:1, but the steady-state levels of total sterols were >40 % those of livers from age-matched (3-month-old) control animals. No significant differences in the levels of LDL receptor or HMG-CoA reductase were observed. The levels of dolichol and coenzyme Q were elevated only modestly (by 64 and 31 %, respectively; p < 0.05, N = 6) in the livers of the SLOS rat model compared to controls; moreover, the chain lengths of these isoprenoids were not different in the two groups. We conclude that hepatic isoprenoid synthesis is marginally elevated in this animal model of SLOS, but without preferential shunting to the nonsterol branches (dolichol and coenzyme Q) of the pathway and without alteration of normal dolichol chain lengths.

Topics: Animals; Anticholesteremic Agents; Cholesterol; Dehydrocholesterols; Disease Models, Animal; Dolichols; Humans; Liver; Oxidoreductases Acting on CH-CH Group Donors; Rats; Rats, Sprague-Dawley; Smith-Lemli-Opitz Syndrome; Terpenes; trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride; Ubiquinone

In a cell-based assay for novel inhibitors, we have discovered that two glycosides of 5-thiomannose, each containing an interglycosidic nitrogen atom, prevented the correct zymogen processing of the prohormone proopiomelanocortinin (POMC) and the transcription factor sterol-regulatory element-binding protein-2 (SREBP-2) in mouse pituitary cells and Chinese hamster ovary (CHO) cells, respectively. In the case of SREBP-2, these effects were correlated with the altered N-linked glycosylation of subtilisin/kexin-like isozyme-1 (SKI-1), the protease responsible for SREBP-2 processing under sterol-limiting conditions. Further examination of the effects of these compounds in CHO cells showed that they cause extensive protein hypoglycosylation in a manner similar to type I congenital disorders of glycosylation (CDGs) since the remaining N-glycans in treated cells were complete (normal) structures. The under-glycosylation of glycoproteins in 5-thiomannoside-treated cells is now shown to be caused by the compromised biosynthesis of the dolichol-linked oligosaccharide (DLO) N-glycosylation donor, although the nucleotide sugars required for the synthesis of DLOs were neither reduced under these conditions, nor were their effects reversed upon the addition of exogenous mannose. Analysis of DLO intermediates by fluorophore-assisted carbohydrate electrophoresis demonstrated that 5-thiomannose-containing glycosides block DLO biosynthesis most likely at a stage prior to the GlcNAc(2) Man(3) intermediate, on the cytosolic face of the endoplasmic reticulum.

Topics: Animals; Cells, Cultured; CHO Cells; Congenital Disorders of Glycosylation; Cricetinae; Disease Models, Animal; Dolichols; Mannose; Mice; Oligosaccharides

In the current study our objective was to develop a murine model of human hyper-IgD syndrome (HIDS) and severe mevalonic aciduria (MA), autoinflammatory disorders associated with mevalonate kinase deficiency (MKD). Deletion of one Mvk allele (Mvk (+/-)) yielded viable mice with significantly reduced liver Mvk enzyme activity; multiple matings failed to produce Mvk (-/-) mice. Cholesterol levels in tissues and blood, and isoprene end-products (ubiquinone, dolichol) in tissues were normal in Mvk (+/-) mice; conversely, mevalonate concentrations were increased in spleen, heart, and kidney yet normal in brain and liver. While the trend was for higher IgA levels in Mvk (+/-) sera, IgD levels were significantly increased (9-12-fold) in comparison to Mvk (+/+) littermates, in both young (<15 weeks) and older (>15 weeks) mice. Mvk (+/-) animals manifested increased serum TNF-alpha as compared to wild-type littermates, but due to wide variation in levels between individual Mvk (+/-) mice the difference in means was not statistically significant. Mvk (+/-) mice represent the first animal model of HIDS, and should prove useful for examining pathophysiology associated with this disorder.

Topics: Alleles; Animals; Disease Models, Animal; Dolichols; Gene Deletion; Gene Frequency; Humans; Immunoglobulin D; Mevalonate Kinase Deficiency; Mice; Mice, Transgenic; Models, Biological; Models, Genetic; Phosphotransferases (Alcohol Group Acceptor); Ubiquinone

An animal model of chronic fluorosis was produced by subjecting Wistar rats to high doses of fluoride in drinking water for a prolonged period. Phospholipid and neutral lipid contents in rat kidney were then analyzed by high-performance liquid chromatography (HPLC), and fatty acid compositions from individual phospholipids were measured by gas chromatography. Lipid peroxidation was detected by the thiobarbituric-acid-reactive substance assay. Results showed that the total phospholipid content significantly decreased in the kidney of the rats treated with high doses of fluoride and the main species influenced were phosphatidylethanolamine (PE) and phosphatidylcholine (PC). Decreased proportions of polyunsaturated fatty acids were observed in PE and PC in kidney of fluoride-treated animals compared to controls. No changes could be detected in the amounts of cholesterol and dolichol in kidneys between the rats treated with fluoride and controls. A significant decrease of ubiquinone in rat kidney was observed in the groups treated with excessive fluoride. High levels of lipid peroxidation were detected in kidney of the rats with fluorosis. It is plausible that the specific modification of lipid composition results from lipid peroxidation. The oxidative stress and modification of cellular membrane lipids may be involved in the pathogenesis of chronic fluorosis and provide a possible explanation for the gross system damage observed in the body, especially in soft tissues and organs.

Topics: Animals; Calcium Fluoride; Cholesterol; Chromatography, High Pressure Liquid; Disease Models, Animal; Dolichols; Fatty Acids, Unsaturated; Female; Fluoride Poisoning; Intracellular Membranes; Kidney; Lipid Peroxidation; Male; Membrane Lipids; Phosphatidylcholines; Phosphatidylethanolamines; Rats; Rats, Wistar; Ubiquinone; Water Supply

The biosynthesis of cholesterol, dolichol and dolichyl-P were investigated in a murine model of Niemann-Pick type C disease using both in vitro and in vivo systems. In vivo incorporation of [3H]mevalonate into squalene, dolichol and dolichyl-P decreased. The amount of dolichyl-P was elevated due to a decrease in the rate of degradation. Labeling of squalene and cholesterol of liver homogenates in vitro was decreased in the diseased mice and a lowering of microsomal activities of both HMG-CoA reductase and squalene synthase were also observed. In experiments with brain homogenate, decreased [3H]mevalonate labeling of squalene, cholesterol and dolichol was found in vitro. The decreases in cis-prenyltransferase and squalene synthase activities were observed at a very early phase of the disease. In contrast to the decreased biosynthesis of cholesterol observed in vitro, the labeling of total liver cholesterol was found to be increased in Niemann-Pick type C liver upon in vivo investigation, possibly due to the accumulation of this lipid as a result of a deficient transport process. In the brain, where in vivo labeling reflects only biosynthesis, a decreased rate of cholesterol synthesis was demonstrated.

Topics: Animals; Brain; Cholesterol; Disease Models, Animal; Dolichol Phosphates; Dolichols; Farnesyl-Diphosphate Farnesyltransferase; Hydroxymethylglutaryl CoA Reductases; Liver; Male; Mevalonic Acid; Mice; Mice, Inbred BALB C; Microsomes, Liver; Niemann-Pick Diseases; Squalene; Transferases; Tritium

Ceroid-lipofuscinosis is described in Australian Cattle dogs. Lesions included storage of ceroid-lipofuscin in most tissues with characteristic ultrastructural inclusion body patterns in neurons and other cells. Dolichol concentration of the affected dog's brain was similar to those in age-matched control dog brains. However, concentrations in brain, liver and kidneys were markedly higher than in a slightly younger dog. Biochemical data including lysosomal enzyme activities exclude other lysosomal storage diseases. The clinical and pathological features of this disorder resemble those of the juvenile Spielmeyer-Vogt type of Batten disease in humans.

Topics: Age Factors; Animals; Cerebral Cortex; Disease Models, Animal; Dog Diseases; Dogs; Dolichols; Genes, Recessive; Lipid Metabolism; Lysosomes; Neuronal Ceroid-Lipofuscinoses; Pedigree

The ceroid lipofuscinoses are inherited lysosomal diseases of children characterized by a fluorescent lipopigment stored in a variety of tissues. Defects in lipid metabolism or the control of lipid peroxidation have been postulated to explain their pathogenesis. In the present study, lipopigment was isolated from the liver of sheep affected with ceroid lipofuscinosis. It was 70% protein, the rest being mainly lipids. These were only one-sixth as fluorescent as total liver lipids, but contained a number of fluorophors. None were major components of the lipopigment or the postulated fluorescent product of lipid peroxidation. Lipopigment lipids included the lysosomal marker bis(monoacylglycero)phosphate that contained 42.9% linoleate and 16.5% linolenate. Lipopigment neutral lipids were dolichol, dolichyl esters, ubiquinone, free fatty acids, and cholesterol, indicative of a lysosomal origin of the lipopigment. Phosphatidylcholine, phosphatidylinositol, phosphatidylserine, and phosphatidylethanolamine were present in proportions and with fatty acid profiles typical of lysosomes. No differences were found between the lipids of total control and affected livers, nor the fatty acid profiles of their phosphatidylcholine, phosphatidylethanolamine, or triglycerides. It is concluded that ovine ceroid lipofuscinosis is not a lipidosis, nor does the lipopigment arise from the abnormal peroxidation of lipids. Strong similarities between the lipopigment and the age pigment lipofuscin were noted.

Topics: Animals; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Disease Models, Animal; Dolichols; Fatty Acids; Fluorescence; Liver; Lysophospholipids; Lysosomes; Magnetic Resonance Spectroscopy; Monoglycerides; Neuronal Ceroid-Lipofuscinoses; Phosphatidic Acids; Phospholipids; Pigments, Biological; Proteins; Sheep; Sheep Diseases; Ubiquinone

Previous studies on the lipopigment from the livers of sheep affected with ceroid lipofuscinosis showed that the disease does not involve a defect in lipid metabolism or abnormal lipid peroxidation and that most of the lipopigment was proteinaceous. In this study, lipopigment was isolated from liver, kidney, pancreas, and brain of affected sheep without the use of proteolytic enzymes. Lipopigment from all tissues was two-thirds protein. Modified silver staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a major band of Mr = 14,800, heterogeneous material between Mr = 5,000 and 9,000, and a major band of Mr = 3,500. These compounds did not stain for RNA or carbohydrate and were digested by a nuclease-free protease as expected for protein. They are not normal lysosomal proteins. Lipopigment levels of dolichol, ubiquinone, and cholesterol were consistent with the lipopigment being protein-enriched lysosome-derived cytosomes. The presence of the Mr = 3,500 proteins in whole affected tissue homogenates distinguished them from homogenates of normal tissues. It was concluded that low Mr proteins are specifically stored in ovine ceroid lipofuscinosis and that the ceroid lipofuscinoses may result from inherited defects in lysosomal protein catabolism.

Topics: Animals; Brain Chemistry; Cholesterol; Disease Models, Animal; Dolichols; Electrophoresis, Polyacrylamide Gel; Fatty Acids; Fluorescence; Kidney; Lipids; Liver; Lysosomes; Molecular Weight; Neuronal Ceroid-Lipofuscinoses; Pancreas; Phospholipids; Pigments, Biological; Proteins; Sheep; Sheep Diseases; Ubiquinone