title: Gene transfer of TRPC6 (dominant negative) restores erectile function in diabetic rats.
abstract: 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.
authors.affiliation: Department of Urology, Institute of Health Science, Gyeongsang National University School of Medicine, 92 Chilam-Dong, Jinju 660-751, Republic of Korea.
authors.forename: Jae Hun
authors.initials: JH
authors.lastname: Jung
authors.forename: Byung Joo
authors.initials: BJ
authors.lastname: Kim
authors.forename: Mee Ree
authors.initials: MR
authors.lastname: Chae
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Kam
authors.forename: Ju-Hong
authors.initials: JH
authors.lastname: Jeon
authors.forename: Insuk
authors.initials: I
authors.lastname: So
authors.forename: Ky Hyun
authors.initials: KH
authors.lastname: Chung
authors.forename: Sung Won
authors.initials: SW
authors.lastname: Lee
mesh_terms: 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
chemical_list: D050052:TRPC Cation Channels; C492145:Trpc6 protein, rat