FOXO3a turns the tumor necrosis factor receptor signaling towards apoptosis through reciprocal regulation of c-Jun N-terminal kinase and NF-kappaB.
OBJECTIVE
We evaluated the full range effects of FOXO3a in endothelial cells (ECs) by microarray analysis and investigated the role of FOXO3a regulating TNF receptor signaling pathway.


RESULTS
Human umbilical vein endothelial cells (HUVECs) were transfected with adenoviral vectors expressing constitutively active FOXO3a (Ad-TM-FOXO3a). Ad-TM-FOXO3a transfection caused remarkable apoptosis, which were accompanied with upregulation of genes related with TNF receptor signaling, such as TNF-alpha, TANK (TRAF-associated NF-kappaB activator), and TTRAP (TRAF and TNF receptor-associated protein). Furthermore, kappaB-Ras1 (IkappaB-interacting Ras-like protein-1) which is known to block IkappaB degradation was found increased, and intranuclear translocation of NF-kappaB was inhibited. GADD45beta and XIAP, negative regulators of c-Jun N-terminal kinase (JNK), were suppressed and JNK activity was increased. Attenuation of TNF signaling pathway either by blocking antibody for TNF receptor or by blocking JNK with DMAP (6-dimethylaminopurine) or Ad-TAM67 (dominant negative c-Jun) cotransfection, significantly reduced FOXO3a-induced apoptosis. Finally, treatment of vasculature with heat shock, an activator of endogenous FOXO3a, resulted in EC apoptosis, which was completely rescued by Ad-TAM67.


CONCLUSIONS
FOXO3a promotes apoptosis of ECs, through activation of JNK and suppression of NF-kappaB. These data identify a novel role of FOXO3a to turn TNF receptor signaling to a proapoptotic JNK-dependent pathway.
Lee
Hae-Young
HY
Innovative Research Institute for Cell Therapy, Seoul National University Hospital, Seoul, Korea.
Youn
Seock-Won
SW
Kim
Ju-Young
JY
Park
Kyung-Woo
KW
Hwang
Chang-Il
CI
Park
Woong-Yang
WY
Oh
Byung-Hee
BH
Park
Young-Bae
YB
Walsh
Kenneth
K
Seo
Jeong-Sun
JS
Kim
Hyo-Soo
HS
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002339:Carotid Arteries / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000502:physiology*; D005822:Genetic Vectors; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D018124:Receptors, Tumor Necrosis Factor / Q000502:physiology*; D015398:Signal Transduction; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology; D015854:Up-Regulation
C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D048031:JNK Mitogen-Activated Protein Kinases