Increased expression of beta-hexosaminidase alpha chain in cultured skin fibroblasts from patients with carbohydrate-deficient glycoprotein syndrome type I.

Abstract

Carbohydrate-deficient glycoprotein (CDG) syndrome type I is an autosomal recessive multisystem disorder characterized by multiple serum glycoproteins with deficient oligosaccharide chains. This characteristic under-glycosylation is found in several serum glycoproteins. We studied secreted forms of lysosomal enzymes, beta-hexosaminidase and alpha-fucosidase, in serum from the patients and media of cultured fibroblasts. Both beta-hexosaminidase and alpha-fucosidase activities were increased in sera from three CDG patients. The enzyme activity staining using the fluorogenic substrate-4-methylumbelliferyl-alpha-L-fucopyranoside after polyacrylamide gel isoelectric focusing revealed abnormal cathodal bands in sera from CDG patients. On the other hand, no abnormal secreted forms of beta-hexosaminidase and alpha-fucosidase were detected in media from cultured CDG fibroblasts by isoelectric focusing and sodium-dodecyl sulfate-polyacrylamide gel electrophoresis. However, SDS-polyacrylamide gel electrophoresis and Western blotting analysis of beta-hexosaminidase using anti-beta-hexosaminidase A (anti-alpha + beta chains) antibody, showed an increase of a 55-kDa mature form of the alpha chain. Northern blotting analysis identified an increase in mRNA levels of beta-hexosaminidase alpha chain in CDG fibroblasts. Although under-glycosylated fractions of these lysosomal enzymes were not detected in cultured fibroblasts, it was suggested that intracellular processing of these lysosomal enzymes in CDG patients might be altered.

• Authors: S Ichisaka, K Ohno, I Yuasa, E Nanba, H Sakuraba, Y Suzuki
• Journal: Brain & development (Brain Dev) Vol. 20 Issue 5 Pg. 302-6 (Aug 1998) ISSN: 0387-7604 [Print] Netherlands
• PMID: 9760999 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• RNA, Messenger
• alpha-L-Fucosidase
• beta-N-Acetylhexosaminidases

Topics

• Blotting, Northern
• Blotting, Western
• Cells, Cultured
• Child
• Child, Preschool
• Congenital Disorders of Glycosylation (blood, enzymology)
• Electrophoresis, Polyacrylamide Gel
• Fibroblasts (enzymology)
• Humans
• Isoelectric Focusing
• RNA, Messenger (metabolism)
• Skin (enzymology, pathology)
• alpha-L-Fucosidase (metabolism)
• beta-N-Acetylhexosaminidases (blood, genetics, metabolism)