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TRPC3 is a critical contributor to the osmosensitivity and renal water handling in the mouse collecting duct
Author(s) -
Tomilin Viktor N.,
Mamenko Mykola,
Zaika Oleg,
Ren Guohui,
Pochynyuk Oleh
Publication year - 2020
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.2020.34.s1.03447
Subject(s) - aquaporin 2 , vasopressin , endocrinology , medicine , chemistry , thirst , reabsorption , nephrogenic diabetes insipidus , water transport , kidney , homeostasis , aquaporin , water flow , biology , biochemistry , mechanical engineering , environmental engineering , water channel , engineering , inlet
Kidney plays a central role in control of systemic water balance depending on hydration status. Arginine vasopressin (AVP) augments water permeability of the collecting duct (CD) by facilitating aquaporin 2 (AQP2) translocation to the apical plasma membrane. Inability of CD to respond to AVP signal causes Nephrogenic Diabetes Insipidus (NDI) leading to polyuria, dehydration and thirst. AVP stimulates CD to reabsorb water, but this can only occur in presence of positive osmotic difference between the cytosol and luminal fluid. Extracellular hypotonicity increases [Ca 2+ ] i and causes cell swelling due to AQP2‐driven water influx. The significance of the osmosensitive [Ca 2+ ] i signaling for renal water transport and urinary concentration remains unknown. TRPC3 is a Ca 2+ permeable mechano‐activated channel abundantly expressed in the CD. Using ratiometric Fura 2‐based [Ca2+]i imaging, we simultaneously measured [Ca 2+ ] i dynamics and the rate of cell swelling as a readout of the AQP2‐dependent water reabsorption in freshly isolated split‐opened CDs of wild type and TRPC3 −/− mice and combined it with immunofluorescent detection of AVP‐induced AQP2 trafficking and assessment of systemic water balance. We found that TRPC3 inhibition or deletion precluded [Ca 2+ ] i elevations induced hypotonicity and remarkably slowed the rate of cell swelling indicative of diminished water transport in the CD. TRPC3 −/− mice had comparable with WT serum and urine osmolarity in the presence of ad libitum water intake, but exhibited a significantly greater bodyweight loss, and larger urinary volume after 24 h water deprivation despite higher AVP levels when compared to WT. Furthermore, osmosensitive [Ca 2+ ] i elevations were greatly increased in CDs from WT but not in TRPC3 −/− animals after 24 h water deprivation. The rate of cell swelling was greatly accelerated in WT, while was only modestly increased in TRPC3 −/− mice under this condition. Using immunofluorescent microscopy, we found that AQP2 translocated to the apical plasma membrane in WT, while remained largely cytosolic in TRPC3 −/− after 24 h water deprivation. Consistently, TRPC3 inhibition interferes with AVP‐induced AQP2 trafficking in cultured mpkCCDc14 cells. In summary, we demonstrate a significant role of TRPC3 in osmosensitivity and regulation of AVP‐dependent AQP2 trafficking in the CD. TRPC3 deletion compromises systemic water balance producing an NDI‐like phenotype. Support or Funding Information American Heart Association Career Development Award for Viktor Tomilin (19CDA34660148) NIH RO1 awards for Oleh Pochynyuk (DK117865 and DK119170)