Alzheimer's disease (AD) is the most prevalent cause of dementia and can be conceptualized as a tauopathy initiated by the accumulation of amyloid-β (Aβ) in the brain. The clinical introduction of ant Show more
Alzheimer's disease (AD) is the most prevalent cause of dementia and can be conceptualized as a tauopathy initiated by the accumulation of amyloid-β (Aβ) in the brain. The clinical introduction of anti-Aβ antibody therapies has marked the beginning of a new era in disease-modifying treatment for dementia. While the deleterious effects of Aβ on postsynaptic spines and axonal microtubules have been increasingly clarified, recent studies have shifted attention beyond extracellular Aβ deposition as senile plaques to the pathogenic significance of intracellular Aβ. In particular, accumulating evidence highlights lysosomes as critical sites of intracellular Aβ toxicity. Interactions between Aβ and gangliosides, v-ATPase-dependent lysosomal acidification, and lysosomal membrane integrity are the key determinants of disease progression. In parallel, additional molecular players, including components of the complement cascade and asparaginyl endopeptidase, have been implicated in linking Aβ pathology to tau dysregulation and neurodegeneration. As therapeutic strategies targeting Aβ enter clinical practice, these emerging pathways represent promising targets for the next generation of AD treatment. Here, we summarize current insights and ongoing therapeutic developments centered on these mechanisms. Show less
The D-glucuronyltransferase and N-acetyl-D-glucosaminyltransferase reactions in heparan sulfate biosynthesis have been associated with two genes, EXT1 and EXT2, which are also implicated in the inheri Show more
The D-glucuronyltransferase and N-acetyl-D-glucosaminyltransferase reactions in heparan sulfate biosynthesis have been associated with two genes, EXT1 and EXT2, which are also implicated in the inherited bone disorder, multiple exostoses. Since the cell systems used to express recombinant EXT proteins synthesize endogenous heparan sulfate, and the EXT proteins tend to associate, it has not been possible to define the functional roles of the individual protein species. We therefore expressed EXT1 and EXT2 in yeast, which does not synthesize heparan sulfate. The recombinant EXT1 and EXT2 were both found to catalyze both glycosyltransferase reactions in vitro. Coexpression of the two proteins, but not mixing of separately expressed recombinant EXT1 and EXT2, yields hetero-oligomeric complexes in yeast and mammalian cells, with augmented glycosyltransferase activities. This stimulation does not depend on the membrane-bound state of the proteins. Show less