Loss of primary cilia results in deregulated and unabated apical calcium entry in ARPKD collecting duct cells

Brian J. Siroky, William B. Ferguson, Amanda L. Fuson, Yi Xie, A. Fintha, Peter Komlosi, Bradley K. Yoder, Erik M. Schwiebert, Lisa M. Guay-Woodford, P. Darwin Bell

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

Recent genetic analysis has identified a pivotal role of primary cilia in the pathogenesis of polycystic kidney disease (PKD). However, little is known regarding how cilia loss/dysfunction contributes to cyst development. In epithelial cells, changes in apical fluid flow induce cilia-mediated Ca 2+ entry via polycystin-2 (PC2), a cation channel. The Oak Ridge Polycystic Kidney (orpk) mouse contains a mutated Tg737 gene that disrupts expression of polaris, a protein required for ciliogenesis. These studies examine the effect of cilia malformation on Ca2+ entry in orpk cilia(-) collecting duct principal cells, and in orpk cells in which wild-type Tg737 was reintroduced, orpk cilia(+). [Ca2+]i was monitored in confluent cell monolayers using fluorescence microscopy. Intrinsic apical Ca2+ entry was measured by Mn2+ quenching and Ca2+ depletion/readdition under flow conditions below the threshold for stimulation. We found that unstimulated apical Ca2+ entry was markedly increased in cilia(-) cells and was sensitive to Gd3+, an inhibitor of PC2. Electrophysiological measurements demonstrate increased abundance of an apical channel, consistent with PC2, in cilia(-) cells. Immunofluorescence studies revealed that PC2, normally expressed on and at the base of cilia in orpk cilia(+) cells, was observed throughout the apical membrane in cilia(-) cells. Furthermore, cilia(-) cells displayed elevated subapical Ca2+ levels measured with the near-membrane Ca2+ indicator FFP-18. We propose that cilia exert a tonic regulatory influence on apical Ca2+ entry, and absence of cilia results in loss of spatial organization of PC2, causing unregulated Ca2+ entry and elevations in subapical [Ca2+], a factor which may contribute to cyst formation.

Original languageEnglish
JournalAmerican Journal of Physiology - Renal Physiology
Volume290
Issue number6
DOIs
Publication statusPublished - Jun 2006

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Autosomal Recessive Polycystic Kidney
Cilia
Calcium
Polycystic Kidney Diseases
Cysts
Collecting Kidney Tubules
Membranes

Keywords

  • Autosomal recessive polycystic kidney disease
  • Ca permeability
  • Oak Ridge Polycystic Kidney
  • Polycystin-2

ASJC Scopus subject areas

  • Physiology

Cite this

Loss of primary cilia results in deregulated and unabated apical calcium entry in ARPKD collecting duct cells. / Siroky, Brian J.; Ferguson, William B.; Fuson, Amanda L.; Xie, Yi; Fintha, A.; Komlosi, Peter; Yoder, Bradley K.; Schwiebert, Erik M.; Guay-Woodford, Lisa M.; Bell, P. Darwin.

In: American Journal of Physiology - Renal Physiology, Vol. 290, No. 6, 06.2006.

Research output: Contribution to journalArticle

Siroky, BJ, Ferguson, WB, Fuson, AL, Xie, Y, Fintha, A, Komlosi, P, Yoder, BK, Schwiebert, EM, Guay-Woodford, LM & Bell, PD 2006, 'Loss of primary cilia results in deregulated and unabated apical calcium entry in ARPKD collecting duct cells', American Journal of Physiology - Renal Physiology, vol. 290, no. 6. https://doi.org/10.1152/ajprenal.00463.2005
Siroky, Brian J. ; Ferguson, William B. ; Fuson, Amanda L. ; Xie, Yi ; Fintha, A. ; Komlosi, Peter ; Yoder, Bradley K. ; Schwiebert, Erik M. ; Guay-Woodford, Lisa M. ; Bell, P. Darwin. / Loss of primary cilia results in deregulated and unabated apical calcium entry in ARPKD collecting duct cells. In: American Journal of Physiology - Renal Physiology. 2006 ; Vol. 290, No. 6.
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abstract = "Recent genetic analysis has identified a pivotal role of primary cilia in the pathogenesis of polycystic kidney disease (PKD). However, little is known regarding how cilia loss/dysfunction contributes to cyst development. In epithelial cells, changes in apical fluid flow induce cilia-mediated Ca 2+ entry via polycystin-2 (PC2), a cation channel. The Oak Ridge Polycystic Kidney (orpk) mouse contains a mutated Tg737 gene that disrupts expression of polaris, a protein required for ciliogenesis. These studies examine the effect of cilia malformation on Ca2+ entry in orpk cilia(-) collecting duct principal cells, and in orpk cells in which wild-type Tg737 was reintroduced, orpk cilia(+). [Ca2+]i was monitored in confluent cell monolayers using fluorescence microscopy. Intrinsic apical Ca2+ entry was measured by Mn2+ quenching and Ca2+ depletion/readdition under flow conditions below the threshold for stimulation. We found that unstimulated apical Ca2+ entry was markedly increased in cilia(-) cells and was sensitive to Gd3+, an inhibitor of PC2. Electrophysiological measurements demonstrate increased abundance of an apical channel, consistent with PC2, in cilia(-) cells. Immunofluorescence studies revealed that PC2, normally expressed on and at the base of cilia in orpk cilia(+) cells, was observed throughout the apical membrane in cilia(-) cells. Furthermore, cilia(-) cells displayed elevated subapical Ca2+ levels measured with the near-membrane Ca2+ indicator FFP-18. We propose that cilia exert a tonic regulatory influence on apical Ca2+ entry, and absence of cilia results in loss of spatial organization of PC2, causing unregulated Ca2+ entry and elevations in subapical [Ca2+], a factor which may contribute to cyst formation.",
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