학술대회안내사전등록초록등록안내초록등록/관리숙박 및 교통
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FKHRL1, a forkhead transcription factor induces endothelial cell apoptosis through activation of c-Jun N-terminal kinase and suppression of NF-κB
서울대학교 의과대학 내과학교실; 서울대학교병원 임상의학연구소 심혈관 연구실; 서울대학교병원 심혈관센터¹ : 서울대학교병원 임상의학연구소 심혈관 연구실 ² : 분당서울대학교병원 심혈관센터³
이해영¹, 유현정² : 정재웅² : 강현재¹ : 조영석³ : 연태진³ : 김효수¹ : 오병희¹ : 이명묵¹ : 박영배¹ : 최윤식¹
Background & Aim: Although the forkhead transcription factor, FKHRL1 is known to induce apoptosis in endothelial cells, its mechanism remains unknown. Fas ligand, which mediates forkhead-induced apoptosis in other cells, is not elevated in endothelial cells. Therefore, we evaluated in HUVECs after FKHRL1 gene expression, the signals of two parallel apoptotic and antiapoptotic pathways, c-Jun N-terminal kinase (JNK) and NF-κB, which may regulate TNFα-mediated gene transcription for cell survival, proliferation, and inflammatory responses.
Methods and Results: Microarray analysis was used to evaluate the full range of effects of FKHRL1 on HUVECs. Adenoviral vectors encoding FKHRL1-triple mutant (TM), FKHRL1-dominant negative (DN), or GFP gene were transfected to HUVECs, and at 16, 24 and 40 hours after transfection, RNAs were isolated and applied to oligonucleotide microarray. The genes that showed a significant change of expression (>2-fold increase or decrease) between groups in triplicate assays were selected and analyzed.
HUVECs infected with adeno-FKHRL1-TM showed remarkable apoptotic change morphologically and by FACS analysis. The expression of TNFα, TANK, TRAF6, TTRAP (TRAF and TNF receptor-associated protein) mRNA were increased, which was confirmed by real-time PCR and corresponded to increased protein expression. JNK activity was increased in an in vitro kinase assay. By the way, mRNA expression of κB-Ras1, which is known to block IκB degradation, was increased. And intranuclear translocation of NF-κB was decreased evaluated by EMSA. On the contrary, those responses were reversed in FKHRL1-DN group and by using DMAP (dimethylaminopurine), the JNK inhibitor, apoptotic change of ECs were attenuated. It suggested that FKHRL1 action might be mediated by JNK.
Conclusion: FKHRL1 suppresses growth and promotes apoptosis of endothelial cells, through activation of JNK and suppression of NF-κB. TANK, TRAF6, TTRAP may function as regulatory mediators which activate JNK, while κB-Ras1 may suppress NF-κB by blocking IκB degradation. These data identify novel signal pathways of forkhead inducing apoptosis of endothelial cells.


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