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동의어 포함

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Title Page

ABSTRACT

Contents

CHAPTER I. Back ground of Protein arginine methyltransferase 10

1. Introduction 11

2. Characteristics of PRMTs 11

3. Regulation of PRMTs activity 14

4. PRMT-knockout mice: biological functions of PRMTs 15

5. PRMTs in embryonic stem cells 17

6. PRMT family in Wnt/β-catenin signaling 20

7. PRMTs in cancer 22

References 32

CHAPTER II. Methylation by protein arginine methyltransferase 1 increases stability of Axin, a negative regulator of Wnt signaling 47

ABSTRACT 48

INTRODUCTION 49

MATERIALS AND METHODS 52

Plasmids 52

Cell culture, transfection and stable cell line 52

Immunoprecipitation, immunoblotting and antibodies 53

In vitro methylation assay 54

Preparation of cytoplasmic and nuclear fractions 54

Luciferase assay 55

Immunofluorenscence analysis 55

Preparation of Xenopus egg extract and Axin degradation assay 56

RESULTS 57

Axin interacts with PRMT1 in vitro and in vivo 57

PRMT1 methylates conserved 378th arginine residue of Axin in vitro(이미지참조) 57

PRMT1 methylates Axin in vivo 58

Methylation of Axin by PRMT1 increases the stability of Axin 59

Methylation of 378th Arg of Axin by PRMT1 enhances interaction between Axin and GSK3β(이미지참조) 60

Knockdown of PRMT1 enhances the level of cytoplasmic β-catenin and β-catenin-dependent transcription activity 62

DISCUSSION 74

References 77

CHAPTER III. Methylation of Smurf2 by protein arginine methyltransferase 1 85

ABSTRACT 86

INTRODUCTION 87

MATERIALS AND METHODS 89

Plasmids 89

Cell culture, transfection and stable cell line 89

Immunoprecipitation, immunoblotting and antibodies 89

In vitro methylation assay 90

RESULTS 91

Methylation of Smurf2 by PRMT1 91

Smurf2 interacts with PRMT1 in vitro and in vivo 91

Identification of methylation sites of Smurf2 92

DISCUSSION 101

References 103

국문초록 108

List of Figures

CHAPTER I. Back ground of Protein arginine methyltransferase 8

Figure 1. Type of Arginine methylation. 27

Figure 2. The PRMT family and its posttranslational modification. 28

Figure 3. Regulation of PRMTs activity. 29

Figure 4. Novel roles of PRMT family in Wnt signaling pathway. 30

CHAPTER II. Methylation by protein arginine methyltransferase 1 increases stability of Axin, a negative regulator of Wnt signaling 8

Figure 1. Axin interacts with PRMT1 in vitro and in vivo. 64

Figure 2. PRMT1 methylates conserved the 378th arginine residue of Axin in vitro. 65

Figure 3. Axin is methylated by PRMT1 in vivo. 66

Figure 4. Methylation of Axin by PRMT1 increases the stability of Axin. 68

Figure 5. PRMT1 regulates the interaction between Axin and GSK3b. 70

Figure 6. Knockdown of PRMT1 enhances the level of cytoplasmic b-catenin and b-catenin-dependent transcription activity. 72

CHAPTER III. Methylation of Smurf2 by protein arginine methyltransferase 1 9

Figure 1. Methylation of Smurf2 by PRMT1 94

Figure 2. Smurf2 interacts with PRMT1 in vitro and in vivo 96

Figure 3. Mapping of methylation domains of Smurf2 by PRMT1 98

Figure 4. Schematic diagram of deletion constructs of Smurf2 and methylation sites. 99

Figure 5. PRMT1 Methylates Smurf2 preferentially at Arg232, Arg234, Arg237, and Arg239. 100

초록보기

 단백질의 arginine 잔기의 methylation은 세포내의 다양한 기능을 하고 있다. 기본적으로 Histone의 methylation을 통하여 gene 발현을 조절하거나, 단백질간의 상호작용 또한 조절 할 수 있다. 또한 transcription의 촉진/억제, 세포 신호전달 과정, 세포들의 분화과정, 그리고 배아의 발생과정 또한 단백질 methylation에 의해 조절되고 있다. 따라서 이러한 단백질 methylation의 부 적절한 조절은 다양한 타입의 암을 유발하는 등 질병발생과도 중요한 역할을 하고 있다. 단백질의 arginine 잔기의 methylation 을 일으키는 효소를 protein arginine methyltransferase (PRMT)라고 명명하며, 이러한 PRMT family 중, 본연구는 PRMT1 의 새로운 substrastes들을 찾고, 세포 신호전달 과정에서의 그 기능을 규명하고자 다음 두가지 주제를 연구하였다.

첫번째, Axin이라는 Wnt signaling의 조절인자가 PRMT1에 의해서 methylation이 됨을 증명함. In vitro와 in vivo methylation실험을 수행한 결과 PRMT1은 Axin의 378번째 arginine잔기를 methylation 시킨다는 것을 알아냄. 또한 Axin의 methylation site는 GSK3와의 interaction을 증가시킴에 따라 Axin의 stability를 조절함을 증명함.

두번째, Smurf1 과 Smurf2 (Smad ubiquitin regulatory factor1 and 2)는 HECT class E3 ligases로써, TGF-β 신호전달 과정에서 Smad 단백질들과 type I 수용체를 ubiqutination 시킨다고 알려졌다. 이 논문에서는 PRMT1 두 Smurf 단백질들 중 오직 Smurf2만을 methylation을 유도한다는 것을 알아냄. 특히 in vitro methylation 실험결과 PRMT1은 Smurf2의 4개의 aginine 잔기를 methylation 시킨다는 것을 알아냄