• Ganglioside metabolism in a transgenic mouse model of Alzheimer's disease: expression of Chol-1a antigens in the brain

      Ariga, Toshio; Yanagisawa, Makoto; Wakade, Chandramohan; Ando, Susumu; Buccafusco, Jerry J; McDonald, Michael P; Yu, Robert K.; Institute of Molecular Medicine and Genetics; Department of Pharmacology and Toxicology (2010-10-4)
      The accumulation of Ab (amyloid b-protein) is one of the major pathological hallmarks in AD (Alzheimer’s disease). Gangliosides, sialic acid-containing glycosphingolipids enriched in the nervous system and frequently used as biomarkers associated with the biochemical pathology of neurological disorders, have been suggested to be involved in the initial aggregation of Ab. In the present study, we have examined ganglioside metabolism in the brain of a double- Tg (transgenic) mouse model of AD that co-expresses mouse/ human chimaeric APP (amyloid precursor protein) with the Swedish mutation and human presenilin-1 with a deletion of exon 9. Although accumulation of Ab was confirmed in the double-Tg mouse brains and sera, no statistically significant change was detected in the concentration and composition of major ganglio-N-tetraosyl-series gangliosides in the double-Tg brain. Most interestingly, Chol-1a antigens (cholinergic neuron-specific gangliosides), such as GT1aa and GQ1ba, which are minor species in the brain, were found to be increased in the double-Tg mouse brain. We interpret that the occurrence of these gangliosides may represent evidence for generation of cholinergic neurons in the AD brain, as a result of compensatory neurogenesis activated by the presence of Ab.
    • The Pathological Roles of Ganglioside Metabolism in Alzheimer's Disease: Effects of Gangliosides on Neurogenesis

      Ariga, Toshio; Wakade, Chandramohan; Yu, Robert K.; Institute of Molecular Medicine and Genetics; Institute of Neuroscience (2011-01-9)
      Conversion of the soluble, nontoxic amyloid β-protein (Aβ) into an aggregated, toxic form rich in β-sheets is a key step in the onset of Alzheimer’s disease (AD). It has been suggested that Aβ induces changes in neuronal membrane fluidity as a result of its interactions with membrane components such as cholesterol, phospholipids, and gangliosides. Gangliosides are known to bind Aβ. A complex of GM1 and Aβ, termed “GAβ”, has been identified in AD brains. Abnormal ganglioside metabolism also may occur in AD brains. We have reported an increase of Chol-1α antigens, GQ1bα and GT1aα, in the brain of transgenic mouse AD model. GQ1bα and GT1aα exhibit high affinities to Aβs. The presence of Chol-1α gangliosides represents evidence for genesis of cholinergic neurons in AD brains. We evaluated the effects of GM1 and Aβ1–40 on mouse neuroepithelial cells. Treatment of these cells simultaneously with GM1 and Aβ1–40 caused a significant reduction of cell number, suggesting that Aβ1–40 and GM1 cooperatively exert a cytotoxic effect on neuroepithelial cells. An understanding of the mechanism on the interaction of GM1 and Aβs in AD may contribute to the development of new neuroregenerative therapies for this disorder.