Yoon Sun Chun

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The lactate dehydrogenase A (LDH-A) gene, whose product participates in normal anaerobic glycolysis and is frequently increased in human cancers, has been identified as a c-Myc-responsive gene. It was of interest, therefore, to compare the effect of glucose deprivation in c-Myc-transformed and nontransformed cells. We observed that glucose deprivation or(More)
Amyloid-β protein precursor (AβPP) is transported to the plasma membrane, where it is sequentially cleaved by α-secretase and γ-secretase. This is called non-amyloidogenic pathway since it precludes the production of amyloid-β (Aβ), the main culprit of Alzheimer's disease (AD). Alternatively, once AβPP undergoes clathrin-dependent endocytosis, it can be(More)
Deposition of amyloid-β (Aβ) in the brain is the main culprit of Alzheimer's disease (AD). Aβ is derived from sequential proteolytic cleavage of amyloid-β precursor protein (APP). Newly synthesized APP is transported from endoplasmic reticulum to the plasma membrane via trans-Golgi network (TGN) after post-translational modification including N- and(More)
Presenilins (PS1 and PS2) are multifunctional proteins involved in a diverse array of molecular and cellular functions, including proteolysis, development, neurogenesis, synaptic plasticity, ion channel regulation and phospholipid metabolism. Mutations in presenilin genes are responsible for the majority of Familial Alzheimer disease (FAD). Consequently,(More)
Ubiquitously expressed Mg(2+)-inhibitory cation (MIC) channels are permeable to Ca2+ and Mg2+ and are essential for cell viability. When membrane cholesterol level was increased by pre-incubating cells with a water-soluble form of cholesterol, the endogenous MIC current in HEK293 cells was negatively regulated. The application of phosphatidylinositol(More)
We found that an extract of Lycoris chejuensis and its three isolated active components, narciclasine, 7-deoxynarciclasine, and 7-deoxy-trans-dihydronarciclasine, each significantly reduced the formation of amyloid-β peptides in HeLa cells transfected with an amyloid precursor protein carrying the Swedish mutation up to 45 ± 3.6%. The extract down-regulated(More)
Previous experiments have shown that combination of herpes simplex virus (HSV) infection and simulated snuff-dipping in hamster buccal pouches enhances the development of micro-invasive squamous cell carcinoma in cheek pouch epithelium. The effect has now been determined of water-extractable components of snuff (snuff-extract) on the growth and the(More)
Amyloid β-peptide (Aβ) pathology is an invariant feature of Alzheimer disease, preceding any detectable clinical symptoms by more than a decade. To this end, we seek to identify agents that can reduce Aβ levels in the brain via novel mechanisms. We found that (20S)-Rg3, a triterpene natural compound known as ginsenoside, reduced Aβ levels in cultured(More)
Human ether-a-go-go-related gene (HERG) K(+) channel underlies the rapidly activating delayed rectifier K(+) conductance (IKr) during normal cardiac repolarization. Also, it may regulate excitability in many neuronal cells. Recently, we showed that enrichment of cell membrane with cholesterol inhibits HERG channels by reducing the levels of(More)