Fibroblasts sialic acid

An increased rate of metabolic clearance has been observed after removal of sialic acid from human, low-density lipoprotein in vivo.472 Sialic acid controls the receptor-mediated uptake of this lipoprotein by fibroblasts. Removal of sialic acid residues accelerates the rate of internalization of the lipoprotein and, subsequently, the regulation of the metabolism of cellular cholesterol.473... 

The lysosomal disorder SASD is characterized by accumulation of the free acid monosaccharide sialic acid in the lysosomal compartment of the cell. Diagnosis is based on the demonstration of abnormal excretion of free, not OGS-bound sialic acid in urine, coupled with accumulation of free sialic acid in cultured fibroblasts, and on microscopic evidence of vacuoles (increased and swollen lysosomes filled with light electron-lucent material in skin biopsy and peripheral blood lymphocytes). The inheritance is autosomal recessive. There are different clinical forms of this disorder an adult form, called Salla disease (SD) or Finnish sialuria (OMIM 604369) infantile SASD (ISSD OMIM 269920) and an intermediate form, severe Salla disease [3,16]. 

The test is performed for diagnosis of all clinical forms of SASD. This analysis is usually done after an initial TLC screening test that is positive for free sialic acid, and an increased free sialic acid value in the quantitative urine determination test. The test is like the quantitative urine test performed with the periodate-TBA assay [5, 22]. However, in this case interference is decreased by prepurification of the sample using ion-exchange chromatography [12]. Fibroblasts are cultured under standardized conditions. Cell lysates are prepared by tip sonification in distilled water and the cleared lysates are applied to small Dowex columns. NeuAc is eluted, freeze dried,... 

Beckman et al. (28) have studied the electrophoretic separation of the acid phosphatase activity in tissue extracts on starch gel at pH 8. They described four electrophoretic bands A, B, C, and D. Table IV (28) shows the distribution of activity in different organ extracts. The ABD pattern predominated in kidney BD in liver, intestine, heart, and skeletal muscle B in skin and D in pancreas. The C component was present in a large number of placentae but not in other adult organs. All four electrophoretic components were inhibited by d-(- -)-tartrate A contained sialic acid, D had a lower pH optimum and was more heat resistant than A, B, and C. Components C and D showed parallel electrophoretic behavior. In human skin fibroblasts grown in tissue culture, the acid phosphatase was generally high and the most common pattern was BD. Almost every culture showed some activity. The BD... 

Cells were grown in RPMI medium plus 5 % fetal bovine serum in 1 mL total volume as described in Materials and Methods. At 24-hr intervals the cells were counted in a Coulter counter. Control cells 0, cells from cultures containing 1000 lU/mL mouse fibroblast interferon , cells from cultures containing bovine brain gangliosides at a concentration corresponding to 35 p.M sialic acid , cells from cultures containing both interferon (1000 IU/mL) and gangliosides (35 p.M sialic acid). 

Fibroblasts from a patient with mucolipidosis I showed a five-fold increase in the level of sialic acid and a lower-than-normal level of lysosomal neuraminidase, which results in impaired catabolism of glycopeptides and glycolipids containing sialic acid. A D-mannosyltransferase has been found in suspensions of Balb/c fibroblasts incubated with GDP-D-[ C]mannose it appears to be present at the cell surface, where it is involved in the synthesis of glycolipids and glycoproteins. ... 

In a patient classified as mucolipidosis I, Ckmzetal (1977) and Spranger /. (1977) demonstrated a severe deficiency of an acid neuraminidase (sialidase N-acetyl neuraminic acid hydrolase, E.C. 3.2.1.18) in his cultured fibroblasts. The patient had a neurodegenerative disorder with myoclonus, skeletal changes like in Hurler disease, and cherry-red spots in the maculae of his eyes. In addition to the neuraminidase defect, the fibroblasts of the patient accumulated abnormal amounts of sialic acid-containing compounds. The patient excreted excessive quantities of sialyloligosaccharides in the urine (Michalski etal 1977). Fibroblasts from the parents of another such patient had activities of neuraminidase which were intermediate between patients and controls (Cantz and... 

Patients with sialidosis store in their tissues and excrete in the urine excessive amounts of sialic acid-containing compounds. As shown in Table 2, there is a 3- to 14-fold elevation in total sialic acid content in patients with the severe form of sialidosis as compared to healthy individuals. More than 80% of this sialic acid is in the bound form. An increase in bound sialic acid was also observed by other investigators in fibroblasts, leukocytes, and urine in patients with both the severe... 

Mendla, K. Baumkotter, J. Rosenau, C. Ulrich-Bott, B. Cantz, M. Defective Lysosomal Release of Glycoprotein-Derived Sialic Acid in Fibroblasts from Patients with Sialic Acid Storage Disease. Biochem. J. 1988, 250, 261-267. 

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