• Cytotoxic effects of G(M1) ganglioside and amyloid beta-peptide on mouse embryonic neural stem cells.

      Yanagisawa, Makoto; Ariga, Toshio; Yu, Robert K.; Institute of Molecular Medicine and Genetics; Institute of Neuroscience (2010-03-22)
      AD (Alzheimer's disease) is a neurodegenerative disease and the most common form of dementia. One of the pathological hallmarks of AD is the aggregation of extracellular Abetas (amyloid beta-peptides) in senile plaques in the brain. The process could be initiated by seeding provided by an interaction between G(M1) ganglioside and Abetas. Several reports have documented the bifunctional roles of Abetas in NSCs (neural stem cells), but the precise effects of G(M1) and Abeta on NSCs have not yet been clarified. We evaluated the effect of G(M1) and Abeta-(1-40) on mouse NECs (neuroepithelial cells), which are known to be rich in NSCs. No change of cell number was detected in NECs cultured in the presence of either G(M1) or Abeta-(1-40). On the contrary, a decreased number of NECs were cultured in the presence of a combination of G(M1) and Abeta-(1-40). The exogenously added G(M1) and Abeta-(1-40) were confirmed to incorporate into NECs. The Ras-MAPK (mitogen-activated protein kinase) pathway, important for cell proliferation, was intact in NECs simultaneously treated with G(M1) and Abeta-(1-40), but caspase 3 was activated. NECs treated with G(M1) and Abeta-(1-40) were positive in the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay, an indicator of cell death. It was found that G(M1) and Abeta-(1-40) interacted in the presence of cholesterol and sphingomyelin, components of cell surface microdomains. The cytotoxic effect was found also in NSCs prepared via neurospheres. These results indicate that Abeta-(1-40) and G(M1) co-operatively exert a cytotoxic effect on NSCs, likely via incorporation into NEC membranes, where they form a complex for the activation of cell death signalling.
    • Genome-wide target profiling of piggyBac and Tol2 in HEK 293: pros and cons for gene discovery and gene therapy

      Meir, Yaa-Jyuhn J; Weirauch, Matthew T; Yang, Herng-Shing; Chung, Pei-Cheng; Yu, Robert K.; Wu, Sareina C-Y; Institute of Molecular Medicine and Genetics; Institute of Neuroscience (2011-03-30)
      Background: DNA transposons have emerged as indispensible tools for manipulating vertebrate genomes with applications ranging from insertional mutagenesis and transgenesis to gene therapy. To fully explore the potential of two highly active DNA transposons, piggyBac and Tol2, as mammalian genetic tools, we have conducted a side-by-side comparison of the two transposon systems in the same setting to evaluate their advantages and disadvantages for use in gene therapy and gene discovery.
    • 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.