RESUMEN
Mutation analysis performed on six Italian families with alpha-mannosidosis type II allowed the identification of five new mutations in the MAN2B1 gene: c.157G>T, c.562C>T, c.599A>T, c.293dupA, c.2402G>A (p.E53X, p.R188X, p.H200L, p.Y99VfsX61, p.G801D). Protein residues G801 and H200 are conserved among the four mammalian alpha-mannosidases cloned to date: human, cattle, cat and mouse. In vitro expression studies demonstrated that both missense mutations expressed no residual alpha-mannosidase activity indicating that they are disease-causing mutations. Modelling into the three-dimensional structure revealed that the p.H200L could involve the catalytic mechanism, whereas p.G801D would affect the correct folding of the enzyme.
Asunto(s)
Mutación Puntual , alfa-Manosidasa/genética , alfa-Manosidosis/genética , Animales , Catálisis , Gatos , Bovinos , Línea Celular , Codón sin Sentido , Consanguinidad , Análisis Mutacional de ADN , Humanos , Italia , Riñón , Lisosomas/enzimología , Ratones , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Mutación Missense , Reacción en Cadena de la Polimerasa , Conformación Proteica , Pliegue de Proteína , Proteínas Recombinantes de Fusión/metabolismo , Especificidad de la Especie , alfa-Manosidasa/química , alfa-Manosidasa/deficiencia , alfa-Manosidasa/metabolismo , alfa-Manosidosis/clasificación , alfa-Manosidosis/enzimologíaRESUMEN
Recent studies have shown a genetic association between glucocerebrosidase deficiencies and Parkinson's disease (PD). To further explore this issue the activity of beta-glucocerebrosidase and the activities of other lysosomal enzymes, alpha-mannosidase, beta-mannosidase, beta-hexosaminidase, and beta-galactosidase have been evaluated in the cerebrospinal fluid (CSF) of PD patients. The activities of alpha-mannosidase, beta-mannosidase, beta-glucocerebrosidase, and beta-hexosaminidase were substantially decreased in the CSF of PD patients, while levels of beta-galactosidase were essentially identical to controls. This study indicates that in PD several lysosomal hydrolases have decreased activities, further supporting a possible link between pathophysiological mechanisms underlying PD and lysosomal hydrolases.