Studies of the regulatory mechanisms of human threonyl-tRNA synthetase in the biosynthesis of angiogenic factors and mucin
인간 threonyl-tRNA synthetase의 혈관신생인자 및 뮤신 생합성 조절 기전에 관한 연구
|dc.description||학위논문 (박사)-- 서울대학교 대학원 약학대학 약학과, 2017. 8. 김성훈.||-|
|dc.description.abstract||Aminoacyl-tRNA synthetases (ARSs) are essential enzymes for protein synthesis to link specific amino acids to their cognate tRNAs. Recent studies have shown that ARSs, considered as a sort of “housekeeping” enzyme, are now involved in a variety of functions such as transcription, translation, proliferation, inflammation, angiogenesis and cell death. This study is focused on the human threonyl-tRNA synthetase (TRS) and its potential role.
In chapter I, the results show that human TRS functions as a translational initiation factor to regulate vertebrate-specific translation initiation via eIF4E homologous protein (4EHP). TRS selectively interacts with 4EHP in a manner similar to the eIF4G interaction with eIF4E. In this way, TRS acts as a scaffold protein to assemble eIF4A, consequently forming eIF4F-like complex. Importantly, complex formation is evolutionary gain-of-function to control protein synthesis of a subset of mRNAs necessary for development of the vertebrate system, verified by endothelial cell migration and vessel formation as well as in vivo zebrafish embryo vascularization assays.
In chapter II, the results show that TRS specifically regulates biosynthesis of mucin1 (MUC1) through catalytic activity. The levels of MUC1 protein are affected by threonine and biosynthesis of MUC1 in pancreatic cancer is sensitive to the activity and expression of TRS that incorporates threonine to MUC1. TRS catalytic inhibitors and threonine starvation attenuate MUC1-dependent pancreatic cancer cell migration. In addition, tissue levels of TRS and MUC1 are positively correlated in clinical tumor specimen and expression of both proteins at high level is associated with poor survival outcome of the patients.
To summarize, chapter I study discovers an unexpected role of TRS in regulating translation initiation in vertebrates and uncovers a previously unidentified cap-dependent translation initiation mechanism that represents an evolutionary gain of function in vertebrates. Chapter II study provides several evidences showing the potential role of TRS in the migration of human pancreatic cancer cells by enhancing MUC1 biosynthesis, suggesting a novel insight into targeting TRS as a new way to pancreatic cancer.
|dc.description.tableofcontents||Chapter I. Threonyl-tRNA synthetase activates vertebrate-specific translational initiation via eIF4E homologous protein 1
Specific interaction of TRS UNE-T region with 4EHP 7
Structure of the TRS UNE-T and 4EHP complex 8
Structural details of the TRS UNE-T and 4EHP interaction 10
Interaction between 4EHP and TRS as a gain of function in vertebrates 12
eIF4G-like function of TRS 13
Functional implication of the TRS and 4EHP complex 16
Vertebrate-specific translational control of angiogenesis via the TRS and 4EHP complex 19
Materials and Methods 56
Chapter II. Inhibition of MUC1 biosynthesis via threonyl-tRNA synthetase suppresses pancreatic cancer cell migration 76
Threonine deprivation reduces MUC1 levels in pancreatic cancer cells 81
Threonine deprivation suppresses pancreatic cancer cell migration 82
TRS regulates MUC1 biosynthesis 83
TRS inhibitors suppress pancreatic cancer cell migration 84
TRS affects pancreatic cancer cell migration 85
TRS and MUC1 levels are positively correlated with pancreatic cancer 86
Materials and Methods 108
|dc.subject||eIF4E homologous protein||-|
|dc.title||Studies of the regulatory mechanisms of human threonyl-tRNA synthetase in the biosynthesis of angiogenic factors and mucin||-|
|dc.title.alternative||인간 threonyl-tRNA synthetase의 혈관신생인자 및 뮤신 생합성 조절 기전에 관한 연구||-|