Deficiency of phospholipase C acting on phosphatidylglycerol in Niemann-Pick disease.
We examined the degradation of a labeled phosphatidylglycerol (PG) by fibroblasts from a normal control and a patient with Niemann-Pick (NP) disease. The control homogenate had both phospholipase A and phospholipase C activities toward PG, but NP cells had only phospholipase A. The PG phospholipase C of control fibroblasts was solubilized by sonication and freezing and thawing, was most active at pH 5.0, and was inhibited by Ca2-, detergents, sphingomyelin, and 5' AMP. Assay of PG phospholipase C in fibroblast cultures from NP patients with sphingomyelinase deficiency (three designated type A and four type B) confirmed absence of activity, whereas cultures from NP patients without sphingomyelinase deficiency (three designated type C and one with neurovisceral lipidoses and vertical supranuclear ophthalmoplegia) had activities close to those of normal controls. These findings substantiate previous observations of low phosphodiesterase activities in NP disease and suggest that the enzymatic function affected by the NP genes includes specificity toward PG and sphingomyelin. Deficiency of PG phospholipase C may explain the accumulation of bis(monoacylglycero)phosphate in NP disease.
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007223:Infant; D008246:Lysophospholipids; D008297:Male; D050178:Monoglycerides; D009542:Niemann-Pick Diseases / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000032:analysis / Q000378:metabolism*; D010740:Phospholipases / Q000172:deficiency*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D010738:Type C Phospholipases / Q000172:deficiency*
D008246:Lysophospholipids; D050178:Monoglycerides; D010712:Phosphatidic Acids; D010715:Phosphatidylglycerols; C012786:bis(monoacylglyceryl)phosphate; D010740:Phospholipases; D010738:Type C Phospholipases; D013108:Sphingomyelin Phosphodiesterase