title: Protein gene product 9.5 and ubiquitin are expressed in metabolically active epithelial cells of normal and pathologic human kidney.
abstract: BACKGROUND
  In a study initially designed to evaluate the specific protein gene product 9.5 expression in parietal epithelial cells of Bowman's capsule, a marked positivity was also observed in the tubular and collecting duct epithelial cells. Since protein gene product 9.5 is an important enzyme in the ubiquitin system of proteolysis, and plays a regulatory role in cell cycle and proliferation, its presence in specific segments of the nephron was of considerable interest.
  
  
  METHODS
  We investigated protein gene product 9.5 and ubiquitin expression in both normal and pathologic renal samples (more than 100 cases) using an immunohistochemical technique.
  
  
  RESULTS
  We found that protein gene product 9.5 and ubiquitin were constantly present in Bowman's capsule parietal cells and tubular/collecting duct epithelial cells, with the strongest positivity in metabolically active and proliferative conditions, such as tubular hypertrophy, cellular regeneration and crescent formation. Conversely, the expression of these molecules was attenuated in atrophic tubules. Podocytes were negative.
  
  
  CONCLUSIONS
  The diffuse presence of the protein gene product 9.5 and ubiquitin in normal and pathologic metabolically active epithelial cells of the nephron suggests that these proteins (and likely the whole ubiquitin-proteasome complex) play a fundamental role in the mechanism upregulating protein metabolism of the kidney and that its expression is correlated with activated cellular functions, like proliferation.
authors.affiliation: Department of Pathology, Bambino Gesù Children's Hospital-Research Institute, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Diomedi-Camassei
authors.forename: Lucilla
authors.initials: L
authors.lastname: Ravà
authors.forename: Evelyne
authors.initials: E
authors.lastname: Lerut
authors.forename: Francesco
authors.initials: F
authors.lastname: Callea
authors.forename: Boudewijn
authors.initials: B
authors.lastname: Van Damme
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D004848:Epithelium / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D007680:Kidney Neoplasms / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D012189:Retrospective Studies; D025801:Ubiquitin / Q000096:biosynthesis*; D043222:Ubiquitin Thiolesterase / Q000096:biosynthesis*
chemical_list: D014408:Biomarkers, Tumor; C482860:UCHL1 protein, human; D025801:Ubiquitin; D043222:Ubiquitin Thiolesterase