Seong Hoon Ahn

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The yeast histone deacetylase Rpd3 can be recruited to promoters to repress transcription initiation. Biochemical, genetic, and gene-expression analyses show that Rpd3 exists in two distinct complexes. The smaller complex, Rpd3C(S), shares Sin3 and Ume1 with Rpd3C(L) but contains the unique subunits Rco1 and Eaf3. Rpd3C(S) mutants exhibit phenotypes(More)
To physically characterize the web of interactions connecting the Saccharomyces cerevisiae proteins suspected to be RNA polymerase II (RNAPII) elongation factors, subunits of Spt4/Spt5 and Spt16/Pob3 (corresponding to human DSIF and FACT), Spt6, TFIIF (Tfg1, -2, and -3), TFIIS, Rtf1, and Elongator (Elp1, -2, -3, -4, -5, and -6) were affinity purified under(More)
The largest subunit of RNA polymerase II contains a unique C-terminal domain important for coupling of transcription and mRNA processing. This domain consists of a repeated heptameric sequence (YSPTSPS) phosphorylated at serines 2 and 5. Serine 5 is phosphorylated during initiation and recruits capping enzyme. Serine 2 is phosphorylated during elongation by(More)
We previously reported that apicidin arrested human cancer cell growth through selective induction of p21(WAF1/Cip1). In this study, the apoptotic potential of apicidin and its mechanism in HL60 cells was investigated. Treatment of HL60 cells with apicidin caused a decrease in viable cell number in a dose-dependent manner and an increase in DNA(More)
As RNA polymerase II (RNApII) transitions from initiation to elongation, Mediator and the basal transcription factors TFIID, TFIIA, TFIIH, and TFIIE remain at the promoter as part of a scaffold complex, whereas TFIIB and TFIIF dissociate. The yeast Ctk1 kinase associates with elongation complexes and phosphorylates serine 2 in the YSPTSPS repeats of the(More)
The traditional cut-off for the cardiothoracic ratio (CTR) by chest X-ray was not originally proposed as a prognostic variable. We investigated an optimal CTR cut-off that could predict clinical outcomes in patients with acute myocardial infarction (AMI). A total of 3,083 AMI patients (65.2 ± 12.0 years, 2,091 males) who underwent successful percutaneous(More)
At the onset of transcription, many protein machineries interpret the cellular signals that regulate gene expression. These complex signals are mostly transmitted to the indispensable primary proteins involved in transcription, RNA polymerase II (RNAPII) and histones. RNAPII and histones are so well coordinated in this cellular function that each cellular(More)
Down-regulation of gelsolin expression is associated with cellular transformation and induction of gelsolin exerts antitumorigenic effects. In this study, we show that protein kinase C (PKC) signaling pathway is required for the induction of gelsolin by the histone deacetylase inhibitor apicidin in HeLa cells. Apicidin induces gelsolin mRNA independently of(More)
Apicidin [cyclo(N-O-methyl-L-tryptophanyl-L-isoleucinyl-D-pipecolinyl-L2-amino-8-oxodecanoyl)] is a fungal metabolite shown to exhibit antiparasitic activity by the inhibition of histone deacetylase (HDAC). In this study, we evaluated apicidin as a potential antiproliferative agent. Apicidin showed a broad spectrum of antiproliferative activity against(More)
Nucleolar ribosomal DNA is tightly associated with silent heterochromatin, which is important for rDNA stability, nucleolar integration and cellular senescence. Two pathways have been described that lead to rDNA silencing in yeast: 1) the RENT (regulator of nucleolar silencing and telophase exit) complex, which is composed of Net1, Sir2 and Cdc14 and is(More)