Efficient gene expression system using the RTP801 promoter in the corpus cavernosum of high-cholesterol diet-induced erectile dysfunction rats for gene therapy.
BACKGROUND
The application of gene therapy for a nonlife-threatening disease, such as erectile dysfunction (ED), requires a higher safety level and more efficacious systems for gene transfer.


OBJECTIVE
To establish a novel technique for gene expression in a rat model of hypercholesterolemic ED that uses the RTP801 promoter, a hypoxia-inducible promoter.


METHODS
Two-month-old male Sprague-Dawley rats were fed a diet containing 4% cholesterol and 1% cholic acid, and age-matched control animals were fed a normal diet, for 3 months.


METHODS
Cavernous expression of hypoxia-inducible factor (HIF)-1alpha was evaluated by Western blot. After intracavernous injection of pSV-Luc or pRTP801-Luc, gene expression was evaluated by luciferase assay, and the gene expression area was evaluated by immunohistochemistry.


RESULTS
HIF-1alpha was up-regulated in the corpus cavernosum of hypercholesterolemic rats. Although pSV-Luc did not induce gene expression in either the control or the cholesterol group, pRTP801-Luc significantly induced gene expression in the cholesterol group and resulted in higher luciferase activity than did pSV-Luc up to 14 days after injection. Immunohistochemistry showed that the gene expression area was also greater in the pRTP801-Luc group than in the pSV-Luc group, but the difference was not as great as that in luciferase activity. This suggests that pRTP801-Luc exerts its effect mainly by inducing promoter activity under hypoxia, not by increasing the number of transfected cells.


CONCLUSIONS
The RTP801 promoter-driven gene expression system increased gene expression in the corpus cavernosum tissue of rats with cholesterol-induced ED. This may be a useful system for the development of gene therapy in vasculogenic ED.
Lee
Minhyung
M
Department of Bioengineering, College of Engineering, Hanyang University, Seoul, Korea.
Ryu
Ji-Kan
JK
Piao
Shuguang
S
Choi
Min Ji
MJ
Kim
Hyun Ah
HA
Zhang
Lu-Wei
LW
Shin
Hwa-Yean
HY
Jung
Haeng In
HI
Kim
In-Hoo
IH
Kim
Sung Wan
SW
Suh
Jun-Kyu
JK
D000818:Animals; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D007172:Erectile Dysfunction / Q000209:etiology / Q000628:therapy*; D015870:Gene Expression; D015316:Genetic Therapy; D006801:Humans; D006937:Hypercholesterolemia / Q000150:complications; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008297:Male; D010413:Penis / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors; D014162:Transfection; D015854:Up-Regulation
D002791:Cholesterol, Dietary; D004268:DNA-Binding Proteins; C000632146:Ddit4 protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012097:Repressor Proteins; D014157:Transcription Factors