Estradiol regulates AQP2 expression in the collecting duct: a novel inhibitory role for estrogen receptor α
Muhammad Umar Cheema, Debra L. Irsik, Yan Wang, William Miller-Little, Kelly A. Hyndman, Eileen S. Marks, Jørgen Frøkiær, Erika I. Boesen, Rikke Norregaard
2015
AJP - Renal Physiology
Cheema MU, Irsik DL, Wang Y, Miller-Little W, Hyndman KA, Marks ES, Frøkiaer J, Boesen EI, Norregaard R. Estradiol regulates AQP2 expression in the collecting duct: a novel inhibitory role for estrogen receptor ␣. While there is evidence that sex hormones influence multiple systems involved in salt and water homeostasis, the question of whether sex hormones regulate aquaporin-2 (AQP2) and thus water handling by the collecting duct has been largely ignored. Accordingly, the present study
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... ated AQP2 expression, localization and renal water handling in intact and ovariectomized (OVX) female rats, with and without estradiol or progesterone replacement. OVX resulted in a significant increase in urine osmolality and increase in p256-AQP2 in the renal cortex at 7 days post-OVX, as well as induced body weight changes. Relative to OVX alone, estradiol repletion produced a significant increase in urine output, normalized urinary osmolality and reduced both total AQP2 (protein and mRNA) and p256-AQP2 expression, whereas progesterone repletion had little effect. Direct effects of estradiol on AQP2 mRNA and protein levels were further tested in vitro using the mpkCCD principal cell line. Estradiol treatment of mpkCCD cells reduced AQP2 at both the mRNA and protein level in the absence of deamino-8-D-AVP (dDAVP) and significantly blunted the dDAVPinduced increase in AQP2 at the protein level only. We determined that mpkCCD and native mouse collecting ducts express both estrogen receptor (ER)␣ and ER and that female mice lacking ER␣ displayed significant increases in AQP2 protein compared with wildtype littermates, implicating ER␣ in mediating the inhibitory effect of estradiol on AQP2 expression. These findings suggest that changes in estradiol levels, such as during menopause or following reproductive surgeries, may contribute to dysregulation of water homeostasis in women. AQP2; estrogen; ER␣; KO mice THE KIDNEY PLAYS A CENTRAL role in the maintenance of body fluid homeostasis, filtering ϳ180 liters of plasma per day and reabsorbing all but a tiny fraction to maintain salt and water balance. The terminal portion of the nephron, the collecting duct, is a key site of water reabsorption (reviewed in Ref. 32). Permeability of the collecting duct to water, and thus its ability to passively reabsorb water from the tubular lumen into the
doi:10.1152/ajprenal.00685.2014
pmid:26062878
fatcat:ongactj6bvb75hi5zgtbge4ca4