Efficient regulation of VEGF expression by promoter-targeted lentiviral shRNAs based on epigenetic mechanism: a novel example of epigenetherapy.
BACKGROUND
We studied a possibility that shRNAs can lead to transcriptional gene activation at the promoter level via epigenetic mechanism.


OBJECTIVE
The purpose of this study was to test the effects on vascular endothelial growth factor (VEGF-A) expression by promoter targeted small hairpin RNAs (shRNAs) in vitro and in experimental animals in vivo using stable local lentiviral gene transfer.


RESULTS
One shRNA was identified which strongly increased VEGF-A expression in C166 endothelial cells at mRNA and protein level whereas another shRNA decreased VEGF-A expression. Quantitative chromatin immunoprecipitation analysis revealed that the repressing shRNA caused epigenetic changes, which increased nucleosome density within the promoter and transcription start site and led to repression of VEGF-A expression. Epigenetic changes caused by the activating shRNA were opposite to those caused by the repressing shRNA. These results were confirmed in vivo in an ischemic mouse hindlimb model after local gene transfer where VEGF-A upregulation achieved by promoter-targeted shRNA increased vascularity and blood flow.


CONCLUSIONS
We show that lentivirus-mediated delivery of shRNA molecules targeted to specific regions in the mVEGF-A promoter either induce or repress VEGF-A expression via epigenetic modulation. Thus, we describe a new approach of gene therapy, epigenetherapy, based on an epigenetic mechanism at the promoter level. Controlling transcription through manipulation of specific epigenetic marks provides a novel approach for the treatment of several diseases.
Turunen
Mikko P
MP
Ark Therapeutics Oy, Kuopio, Finland.
Lehtola
Tiia
T
Heinonen
Suvi E
SE
Assefa
Genet S
GS
Korpisalo
Petra
P
Girnary
Roseanne
R
Glass
Christopher K
CK
Väisänen
Sami
S
Ylä-Herttuala
Seppo
S
D000818:Animals; D002460:Cell Line; D042783:Endothelial Cells / Q000378:metabolism; D044127:Epigenesis, Genetic; D015316:Genetic Therapy / Q000379:methods*; D006614:Hindlimb / Q000098:blood supply*; D007511:Ischemia / Q000235:genetics / Q000628:therapy*; D016086:Lentivirus; D051379:Mice; D011401:Promoter Regions, Genetic; D012313:RNA / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D012313:RNA