Heterologous expression of polycystin-1 inhibits endoplasmic reticulum calcium leak in stably transfected MDCK cells

Kimberly H. Weber, Kyung Lee Eun, Uma Basavanna, Sabina Lindley, Roy C. Ziegelstein, Gregory G. Germino, Michael Sutters

Research output: Contribution to journalArticlepeer-review

Abstract

We previously found that polycystin-1 accelerated the decay of ligand-activated cytoplasmic calcium transients through enhanced reuptake of calcium into the endoplasmic reticulum (ER; Hooper KM, Boletta A, Germino GG, Hu Q, Ziegelstein RC, Sutters M. Am J Physiol Renal Physiol 289: F521-F530, 2005). Calcium flux across the ER membrane is determined by the balance of active uptake and passive leak. In the present study, we show that polycystin-1 inhibited calcium leak across the ER membrane, an effect that would explain the capacity of this protein to accelerate clearance of calcium from the cytoplasm following a calcium release response. Calcium leak was detected by measurement of the accumulation of calcium in the cytoplasm following treatment with thapsigargin. Heterologous polycystin-1, stably expressed in Madin-Darby canine kidney cells, attenuated the thapsigargin-induced calcium peak with no effect on basal calcium stores, mitochondrial calcium uptake, or extrusion of calcium across the plasma membrane. The capacity of polycystin-1 to limit the rate of decay of ER luminal calcium following inhibition of the pump was shown indirectly using the calcium ionophore ionomycin, and directly by loading the ER with a low-affinity calcium indicator. We conclude that disruption of ER luminal calcium homeostasis may contribute to the cyst phenotype in autosomal dominant polycystic kidney disease.

Original languageEnglish (US)
Pages (from-to)F1279-F1286
JournalAmerican Journal of Physiology - Renal Physiology
Volume294
Issue number6
DOIs
StatePublished - Jun 2008

Keywords

  • Autosomal dominant polycystic kidney disease
  • Cell calcium
  • Madin-Darby canine kidney cells
  • Thapsigargin

ASJC Scopus subject areas

  • Physiology
  • Urology

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