The mineralocorticoid receptor (MR) regulates ENaC but not NCC in mice with random MR deletion - Conference Presentation

TY - JOUR

T1 - The mineralocorticoid receptor (MR) regulates ENaC but not NCC in mice with random MR deletion - Conference Presentation

AU - Czogalla, Jan

AU - Vohra, Twinkle

AU - Penton, David

AU - Loffing, Johannes

PY - 2016/4/1

Y1 - 2016/4/1

N2 - The mineralocorticoid receptor (MR) and its ligand aldosterone increase renal sodium reabsorptionvia regulation of the epithelial Na+ channel (ENaC) and the Na-K-ATPase in the renal collecting system. Previous studies suggested that aldosterone also regulates the thiazide-sensitive cotransporter in the renal distal convoluted tubule (DCT). However, whether aldosterone directly regulates NCC via MR, or indirectly through systemic alterations such as changed plasma potassium, remained controversial. We have now generated a mouse model carrying a targeteddeletion of MR in ~16% of cells randomly scattered along the renal tubule (MRko mice). In this model, MR-positive and MR-negative cells can be studied next to each other in the same physiological context via immunofluorescence. To evaluate microscope images objectively, we further developed an ImageJ script allowing radial quantification of optical density, thus allowingcomparison of apical staining intensities. Although newborn MRko mice need NaCl supplementationto thrive, adult MRko do not show any differences to wildtype littermates in terms of general physiology, mRNA and protein expression of renal ion transport proteins and urine concentrating capacity, under both normal and low salt diet. MR-negative cells in the renal collecting system ofMRko mice do not show any detectable alphaENaC expression, while gammaENaC is diffusely distributed over the cytoplasm. In MR-positive cells, these ENaC subunits are targeted to the apicalcell surface. Although dietary Na+ restriction increases NCC abundance and phosphorylation to asimilar extent in control and MRko mice, no differences in NCC regulation were observed between MR-negative and MR-positive DCT cells. In conclusion, MR is crucial for ENaC regulation but dispensable for the maintenance of NCC expression and phosphorylation under control conditionsand for NCC upregulation in response to dietary Na+ restriction.

AB - The mineralocorticoid receptor (MR) and its ligand aldosterone increase renal sodium reabsorptionvia regulation of the epithelial Na+ channel (ENaC) and the Na-K-ATPase in the renal collecting system. Previous studies suggested that aldosterone also regulates the thiazide-sensitive cotransporter in the renal distal convoluted tubule (DCT). However, whether aldosterone directly regulates NCC via MR, or indirectly through systemic alterations such as changed plasma potassium, remained controversial. We have now generated a mouse model carrying a targeteddeletion of MR in ~16% of cells randomly scattered along the renal tubule (MRko mice). In this model, MR-positive and MR-negative cells can be studied next to each other in the same physiological context via immunofluorescence. To evaluate microscope images objectively, we further developed an ImageJ script allowing radial quantification of optical density, thus allowingcomparison of apical staining intensities. Although newborn MRko mice need NaCl supplementationto thrive, adult MRko do not show any differences to wildtype littermates in terms of general physiology, mRNA and protein expression of renal ion transport proteins and urine concentrating capacity, under both normal and low salt diet. MR-negative cells in the renal collecting system ofMRko mice do not show any detectable alphaENaC expression, while gammaENaC is diffusely distributed over the cytoplasm. In MR-positive cells, these ENaC subunits are targeted to the apicalcell surface. Although dietary Na+ restriction increases NCC abundance and phosphorylation to asimilar extent in control and MRko mice, no differences in NCC regulation were observed between MR-negative and MR-positive DCT cells. In conclusion, MR is crucial for ENaC regulation but dispensable for the maintenance of NCC expression and phosphorylation under control conditionsand for NCC upregulation in response to dietary Na+ restriction.

M3 - Conference abstract in journal

VL - 30

JO - FASEB J

JF - FASEB J

SN - 0892-6638

IS - S1

M1 - 4394

T2 - Experimental Biology

Y2 - 2 April 2016 through 6 April 2016

ER -