Akt/FOXO3a signaling modulates the endothelial stress response through regulation of heat shock protein 70 expression.
To identify new antiapoptotic targets of the PI3K-Akt signaling pathway in endothelial cells, adenovirus-mediated Akt1 gene transfer and oligonucleotide microarrays were used to examine Akt-regulated transcripts. DNA microarray analysis revealed that HSP70 expression underwent the greatest fold activation of 12,532 transcripts examined in human umbilical vein endothelial cells (HUVEC) transduced with constitutively active Akt1. Akt1 gene transfer increased HSP70 transcript expression by 24.8-fold as determined by quantitative PCR and promoted a dose-dependent up-regulation of HSP70 protein as determined by Western immunoblot analysis. Gene transfer of FOXO3a, a downstream target of Akt in endothelial cells, significantly suppressed both basal and stress-induced HSP70 protein expression. FOXO3a induced caspase-9-dependent apoptosis in HUVEC, and cotransduction with Ad-HSP70 rescued endothelial cells from FOXO3a-induced apoptosis under basal and stress conditions. Our results identify HSP70 as a new antiapoptotic target of Akt-FOXO3a signaling in endothelial cells that controls viability through modulation of the stress-induced intrinsic cell death pathway.
Kim
Hyo-Soo
HS
Molecular Cardiology/Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
Skurk
Carsten
C
Maatz
Henrike
H
Shiojima
Ichiro
I
Ivashchenko
Yuri
Y
Yoon
Suk-Won
SW
Park
Young-Bae
YB
Walsh
Kenneth
K
D000256:Adenoviridae; D017209:Apoptosis; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology*; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D014471:Umbilical Veins; D001616:beta-Galactosidase / Q000235:genetics
D051858:Forkhead Transcription Factors; D018840:HSP70 Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D051057:Proto-Oncogene Proteins c-akt; D001616:beta-Galactosidase; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases