A novel model of autosomal recessive polycystic kidney questions the role of the fibrocystin C-terminus in disease mechanism

Kidney Int. 2017 Nov;92(5):1130-1144. doi: 10.1016/j.kint.2017.04.027. Epub 2017 Jul 18.


Autosomal recessive polycystic kidney disease (OMIM 263200) is a serious condition of the kidney and liver caused by mutations in a single gene, PKHD1. This gene encodes fibrocystin/polyductin (FPC, PD1), a large protein shown by in vitro studies to undergo Notch-like processing. Its cytoplasmic tail, reported to include a ciliary targeting sequence, a nuclear localization signal, and a polycystin-2 binding domain, is thought to traffic to the nucleus after cleavage. We now report a novel mouse line with a triple HA-epitope "knocked-in" to the C-terminus along with lox P sites flanking exon 67, which encodes most of the C-terminus (Pkhd1Flox67HA). The triple HA-epitope has no functional effect as assayed by phenotype and allows in vivo tracking of Fibrocystin. We used the HA tag to identify previously predicted Fibrocystin cleavage products in tissue. In addition, we found that Polycystin-2 fails to co-precipitate with Fibrocystin in kidney samples. Immunofluorescence studies with anti-HA antibodies demonstrate that Fibrocystin is primarily present in a sub-apical location the in kidney, biliary duct, and pancreatic ducts, partially overlapping with the Golgi. In contrast to previous studies, the endogenous protein in the primary cilia was not detectable in mouse tissues. After Cre-mediated deletion, homozygous Pkhd1Δ67 mice are completely normal. Thus, Pkhd1Flox67HA is a valid model to track Pkhd1-derived products containing the C-terminus. Significantly, exon 67 containing the nuclear localization signal and the polycystin-2 binding domain is not essential for Fibrocystin function in our model.

Keywords: PKHD1 gene; autosomal recessive polycystic kidney disease; fibrocystin; mouse model; protein cleavage.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cilia / metabolism
  • Disease Models, Animal
  • Epitopes / genetics
  • Exons / genetics
  • Female
  • Fluorescent Antibody Technique
  • Gene Knock-In Techniques
  • Hemagglutinin Glycoproteins, Influenza Virus / genetics
  • Humans
  • Kidney / cytology
  • Kidney / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Mutation
  • Nuclear Localization Signals / genetics
  • Nuclear Localization Signals / metabolism
  • Peptide Fragments / genetics
  • Phenotype
  • Polycystic Kidney, Autosomal Recessive / genetics*
  • Polycystic Kidney, Autosomal Recessive / metabolism
  • Protein Domains / genetics*
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / metabolism
  • TRPP Cation Channels / metabolism*


  • Epitopes
  • Hemagglutinin Glycoproteins, Influenza Virus
  • Nuclear Localization Signals
  • Peptide Fragments
  • Pkhd1 protein, mouse
  • Receptors, Cell Surface
  • TRPP Cation Channels
  • polycystic kidney disease 2 protein
  • tyrosyl-prolyl-tyrosyl-aspartyl-valyl-prolyl-aspartyl-tyrosyl-alanine