title: Apical serine protease activity is necessary for assembly of a high-resistance renal collecting duct epithelium.
abstract: OBJECTIVE
  We hypothesized that the serine protease prostasin is necessary for differentiation of a high-resistance renal collecting duct epithelium governed by glucocorticoid.
  
  
  METHODS
  Postnatal rat kidney and adult human kidney was used to study the expression and localization of prostasin. The murine collecting duct cell line (M-1) was cultured in Snapwell inserts to investigate the significance of prostasin for the development of transepithelial electrical resistance (TER).
  
  
  RESULTS
  In the cortex and medulla of rat kidney, prostasin mRNA and protein increased significantly between birth and weaning (day 21) and was detected in collecting ducts. Immunoreactive prostasin was associated with collecting ducts and loops of Henle in human kidney. In rat, adrenalectomy at day 10 had no effect on prostasin mRNA level in kidney at day 20. Cultured M-1 cells exhibited parallel increases in prostasin mRNA, protein and TER 5 days after seeding. Apical addition of the serine protease inhibitor aprotinin to M-1 cell cultures inhibited development of TER and led to aberrant localization of E-cadherin. This effect was mimicked by the protease inhibitor nafamostat. Apical addition of phospholipase C to cleave glycosylphosphatidylinositol (GPI) anchors released prostasin to the medium and attenuated development of TER with time of culture. Disruption of lipid rafts by methyl-β-cyclodextrin attenuated development of TER in M-1 cells. Omission of dexamethasone impaired development of TER in M-1 cells, while prostasin protein abundance and E-cadherin distribution did not change.
  
  
  CONCLUSIONS
  Apical, GPI-anchored, lipid raft-associated serine protease activity, compatible with prostasin, is necessary for the development of a high-resistance collecting duct epithelium.
authors.affiliation: Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Steensgaard
authors.forename: P
authors.initials: P
authors.lastname: Svenningsen
authors.forename: A R
authors.initials: AR
authors.lastname: Tinning
authors.forename: T D
authors.initials: TD
authors.lastname: Nielsen
authors.forename: F
authors.initials: F
authors.lastname: Jørgensen
authors.forename: G
authors.initials: G
authors.lastname: Kjaersgaard
authors.forename: K
authors.initials: K
authors.lastname: Madsen
authors.forename: B L
authors.initials: BL
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000818:Animals; D007611:Aprotinin / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002460:Cell Line; D016764:Cell Polarity; D002784:Cholesterol / Q000378:metabolism; D017097:Electric Impedance; D004848:Epithelium / Q000378:metabolism*; D005260:Female; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006801:Humans; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000502:physiology; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D000099271:Prostasin
chemical_list: D007611:Aprotinin; D015820:Cadherins; D002784:Cholesterol; D017261:Glycosylphosphatidylinositols; D012697:Serine Endopeptidases; D015842:Serine Proteinase Inhibitors; D010738:Type C Phospholipases; D000099271:Prostasin