Gene transfer of TRPC6 (dominant negative) restores erectile function in diabetic rats.
BACKGROUND
Transient receptor potential (TRP) channels play an important role in modulating intracellular Ca(2+) ([Ca(2+)](i)) levels.


OBJECTIVE
We examined the hypothesis that overexpression of TRPC6(DN) (dominant negative) may contribute to decreased [Ca(2+)](i) levels in corporal smooth muscle (CSM). We also investigated whether gene transfer of TRPC6(DN) could restore erectile function in diabetic rats.


METHODS
For the in vitro study, the K(Ca), K(ATP), and TRPC6(DN) channel genes were transferred using cDNA, into cultured human CSM cells and human embryonic kidney cells. For the in vivo study, young adult rats were divided into three groups: normal controls; diabetic controls transfected with vector only; and a diabetic group transfected with pcDNA of the TRPC6(DN) gene.


METHODS
After gene transfer, the effects of reducing [Ca(2+)](i) levels were assessed by Fura-2-based imaging analysis. The intracavernosal pressure (ICP) response to cavernosal nerve stimulation was assessed after intracorporal injection of TRPC6(DN) pcDNA. The transgene expression of the TRPC6(DN) was examined by reverse transcription polymerase chain reaction (RT-PCR) in rats transfected with TRPC6(DN) pcDNA.


RESULTS
Gene transfer of ion channels effectively reduced [Ca(2+)](i). Among these channels, transfer of the TRPC6(DN) gene resulted in the greatest reduction of [Ca(2+)](i) in human CSM. The mean (+/-standard error of the mean) ratio of ICP to mean arterial pressure (BP) in the gene-transfer rats was 79.4 +/- 2.4% (N = 8). This was significantly higher than that in control rats (55.6 +/- 3.7% [N = 8]), and similar to that in the young control rats (83 +/- 2.2% [N = 12]). The RT-PCR showed expression of TRPC6(DN) genes in the transfected rats.


CONCLUSIONS
Gene transfer of TRPC6(DN) not only reduced [Ca(2+)](i) in human CSM but also restored erectile function in diabetic rats. These results suggest that pcDNA transfer of TRPC6(DN) may represent a promising new form of therapy for the treatment of male erectile dysfunction in the future.
Jung
Jae Hun
JH
Department of Urology, Institute of Health Science, Gyeongsang National University School of Medicine, 92 Chilam-Dong, Jinju 660-751, Republic of Korea.
Kim
Byung Joo
BJ
Chae
Mee Ree
MR
Kam
Sung Chul
SC
Jeon
Ju-Hong
JH
So
Insuk
I
Chung
Ky Hyun
KH
Lee
Sung Won
SW
D000818:Animals; D048909:Diabetes Complications / Q000150:complications*; D004195:Disease Models, Animal; D007172:Erectile Dysfunction / Q000209:etiology* / Q000628:therapy*; D018014:Gene Transfer Techniques / Q000295:instrumentation*; D015316:Genetic Therapy / Q000379:methods*; D008297:Male; D051381:Rats; D050052:TRPC Cation Channels / Q000235:genetics*; D016896:Treatment Outcome
D050052:TRPC Cation Channels; C492145:Trpc6 protein, rat