title: Expression and distribution of cyclic GMP-dependent protein kinase-1 isoforms in human penile erectile tissue.
abstract: BACKGROUND
  Besides the bioavailability of nitric oxide (NO), downstream guanine monophosphate (cGMP) effector proteins are also considered to play a significant role in penile vascular disease. In animal studies, a downregulation of the cGMP-dependent protein kinase-1 (cGKI) alpha isoform has been linked to erectile dysfunction and diabetes mellitus. So far, the expression of cGKI alpha and beta isoforms has not been evaluated in human penile erectile tissue.
  
  
  OBJECTIVE
  To evaluate the expression of cGKI alpha and beta isoforms in relation to smooth muscle alpha-actin, cGMP, and endothelial NO synthase (eNOS) in human cavernous arteries (HCAs) and human corpus cavernosum (HCC).
  
  
  METHODS
  Cryostat sections of HCA and HCC were incubated with primary antibodies directed against alpha-actin, cGMP, eNOS, cGKI, cGKI alpha, and cGKI beta. Visualization of double-labeled immunofluorescent stainings was achieved by laser microscopy. Western blot analysis was performed in order to confirm the expression of cGKI isoforms.
  
  
  METHODS
  Expression of cGKI alpha and beta isoforms in relation to smooth muscle alpha-actin, cGMP, and eNOS in human penile erectile tissue.
  
  
  RESULTS
  Immunoreactivities specific for cGKI, cGKI alpha, and cGKI beta were observed within the smooth musculature and the endothelium of cavernous arteries and sinusoids. Double stainings revealed the colocalization of alpha-actin, cGMP, eNOS, and cGKI isoforms. The expression of cGKI isoforms was confirmed by Western blot analysis.
  
  
  CONCLUSIONS
  Our results demonstrate, for the first time, the expression of both cGKI alpha and beta isoforms in the smooth musculature of HCA and HCC. Corresponding to recent findings from animal studies, the presence of cGKI alpha and beta provides further evidence for a significant role of these enzymes in the control of smooth muscle function in human penile erectile tissue.
authors.affiliation: Department of Urology, Hannover Medical School, Hannover, Germany.
authors.forename: Eginhard
authors.initials: E
authors.lastname: Waldkirch
authors.forename: Stefan
authors.initials: S
authors.lastname: Uckert
authors.forename: Katja
authors.initials: K
authors.lastname: Sigl
authors.forename: Florian
authors.initials: F
authors.lastname: Imkamp
authors.forename: Kristina
authors.initials: K
authors.lastname: Langnaese
authors.forename: Karin
authors.initials: K
authors.lastname: Richter
authors.forename: Udo
authors.initials: U
authors.lastname: Jonas
authors.forename: Michael
authors.initials: M
authors.lastname: Sohn
authors.forename: Christian
authors.initials: C
authors.lastname: Stief
authors.forename: Gerald
authors.initials: G
authors.lastname: Wolf
authors.forename: Petter
authors.initials: P
authors.lastname: Hedlund
mesh_terms: D000199:Actins / Q000378:metabolism; D015153:Blotting, Western; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000032:analysis*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis*; D008297:Male; D009130:Muscle, Smooth / Q000502:physiology; D009569:Nitric Oxide / Q000032:analysis; D010410:Penile Erection / Q000502:physiology*; D010413:Penis / Q000201:enzymology*
chemical_list: D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; C015482:protein kinase modulator; D009569:Nitric Oxide; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases; C569718:PRKG1 protein, human