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Diminished TRPV4 activity contributes to compromised [Ca 2+ ] i homeostasis in human ADPKD cells
Author(s) -
Tomilin Viktor N,
Zaika Oleh,
Mamenko Mykola,
Reif Gail,
Wallace Darren,
Pochynyuk Oleh
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1032.5
Subject(s) - autosomal dominant polycystic kidney disease , polycystic kidney disease , homeostasis , medicine , endocrinology , chemistry , microbiology and biotechnology , pkd1 , trpv4 , kidney , transient receptor potential channel , biology , receptor
Polycystic kidney disease (PKD) is a devastating clinically relevant pathology causing graduate decline in kidney function due to development and growth of cysts filled with fluid. No effective pharmacological treatments exist for PKD patients. At the cellular level, defective flow‐mediated [Ca 2+ ] i responses and disrupted [Ca 2+ ] i homeostasis have been repeatedly associated with the development of PKD. Our previous work in rodents demonstrated that the activity of the Ca2+‐permeable TRPV4 channel is imperative for flow‐mediated [Ca2+]i responses in the distal renal tubule. Moreover, TRPV4 function is dramatically decreased in isolated cyst monolayers and systemic stimulation of TRPV4 interferes with PKD progression in PCK 453 rats, an autosomal recessive PKD model. To probe translational implication of this mechanism, we used primary cultured normal human kidney (NHK) and autosomal dominant PKD (ADPKD) cells isolated from patients and determined TRPV4 function and its role in [Ca2+]i signaling. As expected, ADPKD cells failed to respond to elevated flow and had significantly lower basal [Ca2+]i levels of 43±1 nM, when compared to NHK cells (91±1 nM). Application of a selective TRPV4 activator, GSK1016790A (30 nM) elicited more than two times higher [Ca2+]i response in NHK than in ADPKD cells. GSK1016790A‐mediated responses were precluded upon pretreatment with a specific TRPV4 inhibitor, HC‐067047 (4 μM) or a Ca2+‐free media, suggesting a direct TRPV4‐dependent Ca2+ influx. While total TRPV4 levels were comparable in NHK and ADPKD cells, we detected a marked decrease in TRPV4 glycosylation. Consistently, treatment with tunicomycin for 24 hours to prevent glycosylation significantly inhibited TRPV4 activity pointing to a mechanism of reduced TRPV4 function in ADPKD cells. Finally, acute application of TRPV4 antagonist, HC‐067047 significantly reduced basal [Ca2+]i levels in NHK cells but had no measurable effect in ADPKD cells. Overall, we demonstrate that similarly to studies in rodents, TRPV4 function and glycosylation are greatly diminished in primary cultured human ADPKD cells and this is at least partially responsible for their distorted [Ca2+]i signaling. We speculate that TRPV4 stimulation might be beneficial in restoring [Ca2+]i homeostasis in cyst cells thereby counteracting ADPKD progression in humans. Support or Funding Information This research was supported by NIH‐NIDDK DK095029 (to O. Pochynyuk), AHA‐15SDG25550150 (to M. Mamenko)