| Co-Investigator(Kenkyū-buntansha) |
UTSUMI Kouichi the Tokyo Metropolitan Institute of Medical Science, Clinical Genetics, Reserche, 臨床遺伝学研究部門, 研究員 (60291150)
SAKURABA Hitoshi the Tokyo Metropolitan Institute of Medical Science, Clinical Genetics, Reserche, 臨床遺伝学研究部門, 研究員 (60114493)
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| Research Abstract |
The genetic defect of alpha-galactosidase encoded by a.gene localized to the X-chromosomal region, Xq22, results in Fabry disease. This disease is characterized by the systemic intralysosomal accumulation of neutral sphingolipids, predominantly globotriaosylceramide (GbOse_3Cer), in cells of the heart, kidneys, and vascular endothelial system. A screening study revealed that atypical Fabry variants comprised 3% of unrelated male patients with left ventricular hypertrophy referred to a cardiology clinic in Japan. In cases with this late-onset, cardiac form of the disease, two single base substitutions were detected in alpha-galactosidase gene, ^<279>Gln toGlu (Q279E), ^<301>Arg to GIn (R301Q). First, the enzymatic properties of recombinant Q279E, R301Q, and wild-type alpha-galactosidase were studied. Those enzyme activity were not significantly different between them, toward an artificial substrate and the natural substrate, GbOse_3Cer. Immunotitration studies revealed that the two mutant proteins were posttranslationally decreased in lymphoblast cells, derived from two atypical Fabry patients. Then, stabilizing effects of substrate analogous toward Q279E mutant were evaluated. Using lymphoblast and fibroblast cells, substrate analogous, alpha-galactose derivatives, melibiose derivatives, beta-galactose derivatives, beta-xylose derivatives, and glyco-replica peptides were not so effective. Finally, to clarify the pathogenesis underlying atypical Fabry disease, transgenic mice expressing wild-type or a mutant alpha-galactosidase with R301Q substitution were established.
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