Role of AQP2 during apoptosis in cortical collecting duct cells

To study the role of serum and glucocorticoid-inducible kinase-1 (SGK1) in mammalian cells, we compared Na+ transport rates in wild-type (WT) M1 cortical collecting duct cells with M1 populations stably expressing human full-length SGK1, NH2-terminal truncated (ΔN-60) SGK1, “kinase-dead” (K127M) SGK1, and cells that have downregulated levels of SGK1 mRNA (antisense SGK1). Basal rates of transepithelial Na+ transport were highest in full-length SGK1 populations, compared among the above populations. Dexamethasone treatment increased Na+ transport in WT and full-length SGK1 cells 2.7- and 2-fold, respectively. Modest stimulation of Na+ absorption was detected after dexamethasone treatment in ΔN-60 SGK1 populations. However, ΔN-60 SGK1 transport rates remained substantially lower than WT values. Importantly, a combination of high insulin, dexamethasone, and serum failed to significantly stimulate Na+ transport in antisense or K127M SGK1 cells. Additionally, expression of antisense SGK1 significantly decreased transepithelial resistance values. Overall, we concluded that SGK1 is a critical component in corticosteroid-regulated Na+ transport in mammalian cortical collecting duct cells. Furthermore, our data suggest that the NH2 terminus of SGK1 may contain a Phox homology-like domain that may be necessary for effective Na+transport.

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Volume regulation in cortical collecting duct cells: role of AQP2

Biology of the Cell ◽

10.1042/bc20040116 ◽

2005 ◽

Vol 97 (9) ◽

pp. 687-697 ◽

Cited By ~ 39

Author(s):

Paula Ford ◽

Valeria Rivarola ◽

Osvaldo Chara ◽

Marcel Blot-Chabaud ◽

Françoise Cluzeaud ◽

...

Keyword(s):

Volume Regulation ◽

Collecting Duct ◽

Cortical Collecting Duct ◽

Duct Cells ◽

Collecting Duct Cells

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The Angiotensin II Type 1 Receptor-Associated Protein Attenuates Angiotensin II-Mediated Inhibition of the Renal Outer Medullary Potassium Channel in Collecting Duct Cells

Frontiers in Physiology ◽

10.3389/fphys.2021.642409 ◽

2021 ◽

Vol 12 ◽

Author(s):

Juliano Zequini Polidoro ◽

Nancy Amaral Rebouças ◽

Adriana Castello Costa Girardi

Keyword(s):

Angiotensin Ii ◽

Cell Surface ◽

Collecting Duct ◽

Cell Surface Expression ◽

Ang Ii ◽

Cortical Collecting Duct ◽

Duct Cells ◽

Collecting Duct Cells

Adjustments in renal K+ excretion constitute a central mechanism for K+ homeostasis. The renal outer medullary potassium (ROMK) channel accounts for the major K+ secretory route in collecting ducts during basal conditions. Activation of the angiotensin II (Ang II) type 1 receptor (AT1R) by Ang II is known to inhibit ROMK activity under the setting of K+ dietary restriction, underscoring the role of the AT1R in K+ conservation. The present study aimed to investigate whether an AT1R binding partner, the AT1R-associated protein (ATRAP), impacts Ang II-mediated ROMK regulation in collecting duct cells and, if so, to gain insight into the potential underlying mechanisms. To this end, we overexpressed either ATRAP or β-galactosidase (LacZ; used as a control), in M-1 cells, a model line of cortical collecting duct cells. We then assessed ROMK channel activity by employing a novel fluorescence-based microplate assay. Experiments were performed in the presence of 10−10 M Ang II or vehicle for 40 min. We observed that Ang II-induced a significant inhibition of ROMK in LacZ, but not in ATRAP-overexpressed M-1 cells. Inhibition of ROMK-mediated K+ secretion by Ang II was accompanied by lower ROMK cell surface expression. Conversely, Ang II did not affect the ROMK-cell surface abundance in M-1 cells transfected with ATRAP. Additionally, diminished response to Ang II in M-1 cells overexpressing ATRAP was accompanied by decreased c-Src phosphorylation at the tyrosine 416. Unexpectedly, reduced phospho-c-Src levels were also found in M-1 cells, overexpressing ATRAP treated with vehicle, suggesting that ATRAP can also downregulate this kinase independently of Ang II-AT1R activation. Collectively, our data support that ATRAP attenuates inhibition of ROMK by Ang II in collecting duct cells, presumably by reducing c-Src activation and blocking ROMK internalization. The potential role of ATRAP in K+ homeostasis and/or disorders awaits further investigation.

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Role of Per1 and the mineralocorticoid receptor in the coordinate regulation of αENaC in renal cortical collecting duct cells

Frontiers in Physiology ◽

10.3389/fphys.2013.00253 ◽

2013 ◽

Vol 4 ◽

Cited By ~ 20

Author(s):

Jacob Richards ◽

Lauren A. Jeffers ◽

Sean C. All ◽

Kit-Yan Cheng ◽

Michelle L. Gumz

Keyword(s):

Mineralocorticoid Receptor ◽

Collecting Duct ◽

Cortical Collecting Duct ◽

Coordinate Regulation ◽

Duct Cells ◽

Collecting Duct Cells

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Whole cell and unitary amiloride-sensitive sodium currents in M-1 mouse cortical collecting duct cells

AJP Cell Physiology ◽

10.1152/ajpcell.1996.270.4.c998 ◽

1996 ◽

Vol 270 (4) ◽

pp. C998-C1010 ◽

Cited By ~ 7

Author(s):

M. L. Chalfant ◽

T. G. O'Brien ◽

M. M. Civan

Keyword(s):

Collecting Duct ◽

Cell Permeability ◽

Na Channel ◽

Na Channels ◽

Cortical Collecting Duct ◽

Ionic Selectivity ◽

Whole Cell ◽

Duct Cells ◽

Excised Patches ◽

Collecting Duct Cells

Amiloride-sensitive whole cell currents have been reported in M-1 mouse cortical collecting duct cells (Korbmacher et al., J. Gen. Physiol. 102: 761-793, 1993). We have confirmed that amiloride inhibits the whole cell currents but not necessarily the measured whole cell currents. Anomalous responses were eliminated by removing external Na+ and/or introducing paraepithelial shunts. The amiloride-sensitive whole cell currents displayed Goldman rectification. The ionic selectivity sequence of the amiloride-sensitive conductance was Li+ > Na+ >> K+. Growth of M-1 cells on permeable supports increased the amiloride-sensitive whole cell permeability, compared with cells grown on plastic. Single amiloride-sensitive channels were observed, which conformed to the highly selective low-conductance amiloride-sensitive class [Na(5)] of epithelial Na+ channels. Hypotonic pretreatment markedly slowed run-down of channel activity. The gating of the M-1 Na+ channel in excised patches was complex. Open- and closed-state dwell-time distributions from patches that display one operative channel were best described with two or more exponential terms each. We conclude that 1) study of M-1 whole cell Na+ currents is facilitated by reducing the transepithelial potential to zero, 2) these M-1 currents reflect the operation of Na(5) channels, and 3) the Na+ channels display complex kinetics, involving > or = 2 open and > or = 2 closed states.

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Lipidomic and proteomic analysis of exosomes from mouse cortical collecting duct cells

The FASEB Journal ◽

10.1096/fj.201700417r ◽

2017 ◽

Vol 31 (12) ◽

pp. 5399-5408 ◽

Cited By ~ 28

Author(s):

Viet D. Dang ◽

Kishore Kumar Jella ◽

Ragy R. T. Ragheb ◽

Nancy D. Denslow ◽

Abdel A. Alli

Keyword(s):

Proteomic Analysis ◽

Collecting Duct ◽

Cortical Collecting Duct ◽

Duct Cells ◽

Collecting Duct Cells

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Protein Kinase D Stabilizes Aldosterone-Induced ERK1/2 MAP Kinase Activation in Renal M1 Cortical Collecting Duct Cells To Promote Cell Proliferation.

10.1210/endo-meetings.2010.part3.p13.p3-612 ◽

2010 ◽

pp. P3-612-P3-612

Author(s):

R Dooley ◽

V McEneaney ◽

BJ Harvey ◽

W Thomas

Keyword(s):

Cell Proliferation ◽

Protein Kinase ◽

Map Kinase ◽

Collecting Duct ◽

Protein Kinase D ◽

Cortical Collecting Duct ◽

Kinase Activation ◽

Promote Cell Proliferation ◽

Duct Cells ◽

Collecting Duct Cells

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Response of rat inner medullary collecting duct to epidermal growth factor

AJP Renal Physiology ◽

10.1152/ajprenal.1989.256.6.f1117 ◽

1989 ◽

Vol 256 (6) ◽

pp. F1117-F1124 ◽

Cited By ~ 2

Author(s):

R. C. Harris

Keyword(s):

Growth Factor ◽

Binding Sites ◽

Collecting Duct ◽

Affinity Binding ◽

Inner Medullary Collecting Duct ◽

Duct Cells ◽

Epidermal Growth ◽

Collecting Duct Cells ◽

Medullary Collecting Duct

Urine is an abundant source of epidermal growth factor (EGF) and prepro-EGF has been localized to the thick ascending limb and distal convoluted tubule of the kidney. However, the functional role of EGF in the kidney is poorly understood. Determination of EGF receptors and functional responses to EGF in intrarenal structures distal to the site of renal EGF production may prove critical to our understanding of the role of this peptide. These studies were designed to investigate the response to EGF of rat inner medullary collecting duct cells in culture and in freshly isolated suspensions. Primary cultures of inner medullary collecting duct cells demonstrated equilibrium binding of 125I-labeled EGF at 4 and 23 degrees C. At 23 degrees C, there was 89 +/- 1% specific binding (n = 30). Scatchard analysis of 125I-EGF binding suggested the presence of both high-affinity binding with a dissociation constant (Kd) of 5 X 10(-10) M and maximal binding sites (Ro) of 2.7 X 10(3) binding sites/cell and low-affinity binding, with Kd of 8.3 X 10(-9) M and Ro of 1.8 X 10(4) binding sites/cell. Bound EGF, 68 +/- 3%, was internalized by 45 min. EGF binding was not inhibited by antidiuretic hormone, atrial natriuretic peptide or bradykinin at 23 degrees C, but there was concentration-dependent inhibition of binding by transforming growth factor-alpha. Incubation with phorbol myristate acetate decreased 125I-EGF binding in a concentration-dependent manner. 125I-EGF binding was also demonstrated in freshly isolated suspensions of rat inner medullary collecting duct cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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