Systematic analysis of inter-species genetic regulation of longevity

국문 초록 (Abstract)

장내미생물은 mammal에게 여러 이로운 역할을 하는 것이 잘 알려져 있으며, 이들에게 문제가 생기면 gastrointestinal disorder, Crohn's disease, cancer, autoimmune disease, neurodegenerative disease, and metabolic syndrome 등 많은 질병을 일으키게 된다. 이들 중 cancer, neurodegenerative disease, and metabolic syndrome은 노화와 관련된 질병이기 때문에 장내미생물은 수명에도 영향을 줄 것으로 생각된다. 그러나 mammal을 이용한 장내미생물이 노화에 미치는 영향을 알아보기 위한 실험은 높은 비용, 긴 시간, 윤리적 문제로 어려운 것이 사실이다. 따라서, 이 연구에서는 장내미생물이 노화에 미치는 영향을 알아보기 위해 C. elegans와 3792종의 E. coli mutants를 각각 host와 장내미생물로 하여 genome wide screen을 진행하였다. 그 결과, 17개의 E. coli mutant는 C. elegans의 수명을 증가시키고, 27의 mutant는 C. elegans의 수명을 감소시키는 것을 확인하였다. C. elegans의 수명을 증가시킨 17개의 mutant candidate중 methylglyoxal을 적게 만드는 hns E. coli mutant에서 DAF-16/FOXO를 통해 C. elegans의 수명을 증가시키는 것을 확인하였다. 또한, C. elegans의 수명을 감소시킨 27개의 mutant candidates 중 MG를 분해하는 gloA와 ydjG가 overexpress되었을 때 C. elegans의 수명을 증가시키는 것을 확인하였으며, 이들 또한 C. elegans의 DAF-16/FOXO를 통해 C. elegans의 수명을 늘리는 것으로 확인하였다. 이 data들은 bacteria-derived MG가 host의 수명 조절 pathway를 modulation하여 host의 수명을 조절하는 것을 가리킨다. 종합적으로, 이 연구는 장내미생물의 bacteria-derived MG가 새로운 노화, 그리고 노화 관련 질환들의 치료 타겟임을 보여준다.

다국어 초록 (Multilingual Abstract)

It is well known that gut microbes play a number of beneficial roles in mammals, and when problems occur in them, they cause many diseases such as gastrointestinal disorder, Crohn's disease, cancer, autoimmune disease, neurodegenerative disease, and metabolic syndrome. Among aging are difficult due to high cost, long time, and ethical issues. Therefore, in this study, genome wide screens were performed using Caenorhabditis elegans and 3792 Escherichia coli mutants as hosts and gut microbes, respectively, to investigate the effect of gut microbes on aging. As a result, it was confirmed that 17 E. coli mutants increased the lifespan of C. elegans, and 27 E. coli mutants decreased the lifespan of C. elegans. Among the 17 mutant candidates that increased the lifespan of C. elegans, it was confirmed that the hns E. coli mutant, which produce less methylglyoxal, increased the lifespan of C. elegans through DAF-16/FOXO. In addition, it was confirmed that the lifespan of C. elegans increased when gloA and ydjG, which degrade Methylglyoxal (MG), were overexpressed among 27 mutant candidates that reduced the lifespan of C. elegans, and these were also confirmed to increase the lifespan of C. elegans via DAF-16/FOXO of C. elegans. These data indicate that bacteria-derived MG modulate the lifespan of a host through the lifespan regulate pathway of host. Taken together, this study shows that bacteria-derived MG of gut microbes is a therapeutic target for novel aging and age-related diseases.

목차 (Table of Contents)

• List of Figures iii
• List of Tables iv
• ABSTRACT v
• Introduction 1
• 1. Gut microbes 2
• 2. C. elegans 3
• 3. C. elegans and gut microbes 5
• 4. H-NS and methylglyoxal 11
• 5. Aims of the study 14
• Materials and Methods 15
• 1. Lifespan screening 16
• 2. E. coli strain 17
• 3. C. elegans 17
• 4. Lifespan assay 18
• 5. Thrashing assay 19
• 6. Measurement of growth rate 19
• 7. Brood size assay 20
• 8. Thermotolerance assay 20
• 9. Dauer assay 20
• 10. Quantification of Methylglyoxal using HPLC 21
• Results 23
• 1. Genetic regulation of longevity on gut microbes - host interspecies 24
• 2. hns mutant E. coli extends not only lifespan but also health span. 29
• 3. hns mutant E. coli extends the lifespan of C. elegans via DAF-16/FOXO. 35
• 4. Bacteria-derived methylglyoxal modulates the lifespan of host. 41
• 5. Bacteria-derived metabolite MG regulates the lifespan of C. elegans through DAF-16/FOXO. 46
• Discussion 51
• Reference 55
• 국문 초록 59