니코틴아마이드를 처리한 세포에서 Sp1 전사조절인자의 안정성과 당화의 감소기전 = Downregulation of O-glycosylation and stability of Sp1 transcription factor in nicotinamide-treated cells

다국어 초록 (Multilingual Abstract)

ABSTRACT
Nicotinamide(NAM) is a form of the B-complex vitamin, niacin. Nicotinamide is incorporated into nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). NAD and NADP function as coenzymes in a wide variety of enzymatic oxidation-reduction reactions essential for tissue respiration, lipid metabolism, and glycogenolysis. In yeast, NAM treatment inhibits Sir2, an NAD-dependent HDAC, which is an essential factor for the effect of calorie restriction in proliferative life span. Interestingly, in contrast to the case in yeast, continuous treatment of NAM caused a significant increase in the life span of normal human fibroblsts. In addition, NAM suppresses the p21WAF1 gene induction in human cells. In this study, the underlying mechanism(s) of the nicotinamide-mediated p21 down-regulation was sought. Since p21WAF1 is regulated by Sp1 transcription factor, the status of Sp1 level was examined in the cells treated with NAM. NAM treatment caused a substantial decrease in the Sp1 protein level and O-glycosylation. The decrease of Sp1 was not detected when NAM was treated along with ALLN, a proteasome inhibitor, or 2-deoxyglucose, an inhibitor of protein de-GlcNAcylation. Rapid downregulation of Sp1 is likely due to hypoglycosylation-induced degradation by proteasome.

Key words: Nicotinamide, Sp1, O-GlcNAcylation, p21WAF1

목차 (Table of Contents)

• TABLE OF CONTENTS
• ABSTRACT …………………………………………………………………… ⅱ
• LIST OF FIGURES ………………………………………………………………………iv
• 1. INTRODUCTION ……………………………………………………………………… 1
• 2. MATERIALS AND METHODS …………………………………………………………………………4
• 2.1. Materials and Cell culture ……………………………………………………………………… 4
• 2.2. Western Analysis …………………………………………………………………………4
• 2.3. Immunoprecipitation …………………………………………………………………………5
• 2.4. RT-PCR ……………………………………………………………………… 5
• 3. RESULT ……………………………………………………………………… 7
• 3.1. Status of Sp1 mRNA and protein in nicotinamide-treated cells ………………………………………………………………………7
• 3.2. Protection of Sp1 proteins from proteasome-mediated degradation in the NAM-treated cells. ………………………………………………………………………7
• 3.3. GlcNAcylation status of total proteins and Sp1 in NAM-Treated cells…………………………………………………………………8
• 3.4. Antagonistic effect of 2-DG on the NAM-induced Sp1degradation ……………………………………………………………………… 9
• 4. DISCUSSION ……………………………………………………………………… 14
• 5. REFERENCES ……………………………………………………………………… 18
• 국문초록 ………………………………………………………………………22