Koon-Sea Hui

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Neurofibrillary tangles (NFT) containing tau are a hallmark of neurodegenerative diseases, including Alzheimer's disease (AD). NFT burden correlates with cognitive decline and neurodegeneration in AD. However, little is known about mechanisms that protect against tau-induced neurodegeneration. We used a cross species functional genomic approach to analyze(More)
Accumulation of neurotoxic hyperphosphorylated TAU protein is a major pathological hallmark of Alzheimer disease and other neurodegenerative dementias collectively called tauopathies. Puromycin-sensitive aminopeptidase (PSA/NPEPPS) is a novel modifier of TAU-induced neurodegeneration with neuroprotective effects via direct proteolysis of TAU protein. Here,(More)
Accumulation of misfolded neurotoxic Cu, Zn-superoxide dismutase-1 (SOD1) protein found in both familial and sporadic amyotrophic lateral sclerosis (ALS) is recognized as an important contributing factor of neuronal cell death. However, little is known about the mechanisms controlling the accumulation and turnover of SOD1 protein. Puromycin-sensitive(More)
In a continuing study of proteolysis of CNS proteins by CNS enzymes, neurofilament proteins (210 K, 155 K, 70 K) and desmin were separated, and the breakdown of individual proteins by purified brain cathepsin D was measured and compared to breakdown by plasma thrombin. With both cathepsin D and thrombin, the rate of breakdown of the 70 K protein was the(More)
The major breakthrough discovery of enkephalins as endogenous opiates led our attempts to determine their inactivation mechanisms. Because the NH2-terminal tyrosine is absolutely necessary for the neuropeptides to exert analgesic effects, and aminopeptidase activities are extraordinarily high in the brain, a specific “amino-enkephalinase” should exist.(More)
Neuron-specific aminopeptidase (NAP) and the ubiquitous puromycin-sensitive aminopeptidase (PSA) were compared in the rat hippocampus during early development. Hippocampus contains the highest amount of NAP determined by a fast-protein liquid chromatography-aminopeptidase analyzer using Leu β-naphthylamide as substrate. Both enzymes were found in the(More)
Neuropeptides are formed from sedentary precursors to smaller, active peptides by processing enzymes cleaving at paired basic residues. The process generates peptide intermediates with additional Lys or Arg residues at their NH2 and COOH termini; the N-terminal basic amino acids are later removed by specific aminopeptidases. We report here a novel(More)
During the purification of opiate receptor by affinity chromatography on wheat germ agglutinin-agarose, an aminopeptidase is coeluted with the receptor. Virtually all of both the enzyme and the receptor is retained on the hydroxylapatite column. The aminopeptidase functions optimally at neutral pH and is activated by Mn2+. The enzyme is sensitive to(More)
We developed monoclonal antibodies (mAbs) against two isozymes of a cytosolic puromycin-sensitive aminopeptidase (PSA-I and PSA-II) purified from chicken brain. The isozymes could be distinguished using Ouchterlony double-immunodiffusion and Western immunoblot. Their distribution in neuronal and glial cells as visualized by indirect immunofluorescence with(More)