Molecular consequences of the pathogenic mutation in feline GM1 gangliosidosis.
Mol Genet Metab
; 94(2): 212-21, 2008 Jun.
Article
em En
| MEDLINE
| ID: mdl-18353697
ABSTRACT
G(M1) gangliosidosis is an inherited, fatal neurodegenerative disease caused by deficiency of lysosomal beta-d-galactosidase (EC 3.2.1.23) and consequent storage of undegraded G(M1) ganglioside. To characterize the genetic mutation responsible for feline G(M1) gangliosidosis, the normal sequence of feline beta-galactosidase cDNA first was defined. The feline beta-galactosidase open reading frame is 2010 base pairs, producing a protein of 669 amino acids. The putative signal sequence consists of amino acids 1-24 of the beta-galactosidase precursor protein, which contains seven potential N-linked glycosylation sites, as in the human protein. Overall sequence homology between feline and human beta-galactosidase is 74% for the open reading frame and 82% for the amino acid sequence. After normal beta-galactosidase was sequenced, the mutation responsible for feline G(M1) gangliosidosis was defined as a G to C substitution at position 1448 of the open reading frame, resulting in an amino acid substitution at arginine 483, known to cause G(M1) gangliosidosis in humans. Feline beta-galactosidase messenger RNA levels were normal in cerebral cortex, as determined by quantitative RT-PCR assays. Although enzymatic activity is severely reduced by the mutation, a full-length feline beta-galactosidase cDNA restored activity in transfected G(M1) fibroblasts to 18-times normal. beta-Galactosidase protein levels in G(M1) tissues were normal on Western blots, but immunofluorescence analysis demonstrated that the majority of mutant beta-galactosidase protein did not reach the lysosome. Additionally, G(M1) cat fibroblasts demonstrated increased expression of glucose-related protein 78/BiP and protein disulfide isomerase, suggesting that the unfolded protein response plays a role in pathogenesis of feline G(M1) gangliosidosis.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Doenças do Gato
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Gangliosidose GM1
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Beta-Galactosidase
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Mutação de Sentido Incorreto
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article