title: FK506-binding protein localizations in human penile innervation.
abstract: OBJECTIVE
  To determine if FK506-binding proteins (FKBPs) are localized to the autonomic nerve supply of the human penis because FK506 (an immunosuppressant drug) has been linked to enhanced nerve regeneration after nerve injury and neurodegenerative diseases by binding to FKBPs, a select group of immunophilins.
  
  
  METHODS
  Human lower genitourinary tract specimens were obtained and embedded in paraffin wax. The tissue was sectioned (10 microm) and processed for immunohistochemistry using antibodies for FKBPs 12, 38, 52, 65, 135 and neuronal nitric oxide synthase (nNOS). To confirm specificity of the antibody, we processed some tissue in the absence of primary antibody, with mouse or rabbit IgG, and with a blocking peptide for FKBP12.
  
  
  RESULTS
  In the pelvis, immunoreactivity for all the FKBPs and nNOS was localized to the periprostatic ganglia although FKBP12 was the only FKBP localized to nerve bundles in this location. In penile tissue, immunoreactivity for all five FKBPs and nNOS was localized to nerves, although immunoreactivity for FKBP38 was minimal. The FKBPs were also evident in epithelial, endothelial and smooth muscle cells of the prostate and penis. Negative controls did not produce staining.
  
  
  CONCLUSIONS
  Identification and localization of immunophilins to nerves coursing in prostate and penile tissue suggest a likely molecular basis to apply immunophilin ligand therapy to protect or regenerate cavernosal nerves. Our findings support the hypothesis that immunosuppressant drugs such as FK506, working via specific receptor mechanisms, are potentially useful to sustain erectile function in men after radical prostatectomy.
authors.affiliation: Department of Urology, The Johns Hopkins Medical Institutions, Baltimore, MD 21287-2411, USA.
authors.forename: Gwen
authors.initials: G
authors.lastname: Lagoda
authors.forename: Sena F
authors.initials: SF
authors.lastname: Sezen
authors.forename: Tongyun
authors.initials: T
authors.lastname: Liu
authors.forename: Ahmet
authors.initials: A
authors.lastname: Höke
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Burnett
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D007150:Immunohistochemistry; D020104:Immunophilins / Q000493:pharmacokinetics*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D018783:Impotence, Vasculogenic / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009416:Nerve Regeneration / Q000187:drug effects*; D009474:Neurons / Q000737:chemistry; D052248:Nitric Oxide Synthase Type I / Q000032:analysis*; D010413:Penis / Q000294:innervation*; D011467:Prostate / Q000294:innervation*; D011468:Prostatectomy / Q000009:adverse effects; D016559:Tacrolimus / Q000627:therapeutic use; D022021:Tacrolimus Binding Proteins / Q000032:analysis*
chemical_list: D007166:Immunosuppressive Agents; D052248:Nitric Oxide Synthase Type I; D022021:Tacrolimus Binding Proteins; D020104:Immunophilins; D016559:Tacrolimus