Identification of a regulated Na/K/Cl cotransport system in a distal nephron cell line

Fan, Pei-Ching; Haas, Mark; Middleton, John

doi:10.1016/0005-2736(92)90276-r

Cited by 11 publications

(6 citation statements)

References 29 publications

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“…Ouabain-sensitive 86 Rb ϩ uptake accounted for ϳ38% of total uptake, consistent with previously reported values in A6 cells (16). The remaining 86 Rb ϩ uptake was a result of the activity of the bumetanide-sensitive Na ϩ -K ϩ -2Cl Ϫ cotransporter (NKCC) (16), as well as from K ϩ channels, which are abundantly expressed in the basolateral membrane of A6 cells (7,13). Because ouabain-sensitive 86 Rb ϩ uptake was linear for at least 40 min (Fig.…”

Section: Resultssupporting

confidence: 90%

SGK1 activates Na⁺-K⁺-ATPase in amphibian renal epithelial cells

Rosa¹,

Gíménez²,

Forbush³

et al. 2006

American Journal of Physiology-Cell Physiology

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Serum- and glucocorticoid-induced kinase 1 (SGK1) is thought to be an important regulator of Na(+) reabsorption in the kidney. It has been proposed that SGK1 mediates the effects of aldosterone on transepithelial Na(+) transport. Previous studies have shown that SGK1 increases Na(+) transport and epithelial Na(+) channel (ENaC) activity in the apical membrane of renal epithelial cells. SGK1 has also been implicated in the modulation of Na(+)-K(+)-ATPase activity, the transporter responsible for basolateral Na(+) efflux, although this observation has not been confirmed in renal epithelial cells. We examined Na(+)-K(+)-ATPase function in an A6 renal epithelial cell line that expresses SGK1 under the control of a tetracycline-inducible promoter. The results showed that expression of a constitutively active mutant of SGK1 (SGK1(T)(S425D)) increased the transport activity of Na(+)-K(+)-ATPase 2.5-fold. The increase in activity was a direct consequence of activation of the pump itself. The onset of Na(+)-K(+)-ATPase activation was observed between 6 and 24 h after induction of SGK1 expression, a delay that is significantly longer than that required for activation of ENaC in the same cell line (1 h). SGK1 and aldosterone stimulated the Na(+) pump synergistically, indicating that the pathways mediated by these molecules operate independently. This observation was confirmed by demonstrating that aldosterone, but not SGK1(T)(S425D), induced an approximately 2.5-fold increase in total protein and plasma membrane Na(+)-K(+)-ATPase alpha(1)-subunit abundance. We conclude that aldosterone increases the abundance of Na(+)-K(+)-ATPase, whereas SGK1 may activate existing pumps in the membrane in response to chronic or slowly acting stimuli.

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Section: Resultssupporting

confidence: 90%

SGK1 activates Na⁺-K⁺-ATPase in amphibian renal epithelial cells

Rosa¹,

Gíménez²,

Forbush³

et al. 2006

American Journal of Physiology-Cell Physiology

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“…The Na ϩ /K ϩ /2Cl Ϫ co-transporter, which is responsible for chloride loading of the cells, has been demonstrated to be stimulated by cAMP (33). In the experiments summarized in Fig.…”

Section: Resultsmentioning

confidence: 99%

Reciprocal Protein Kinase A Regulatory Interactions between Cystic Fibrosis Transmembrane Conductance Regulator and Na+/H+ Exchanger Isoform 3 in a Renal Polarized Epithelial Cell Model

Bagorda

Guerra

Sole

et al. 2002

Journal of Biological Chemistry

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Although Cystic fibrosis transmembrane conductance regulator (CFTR) has been shown to regulate the activity of NHE3, the potential reciprocal interaction of NHE3 to modulate the protein kinase A (PKA)-dependent regulation of CFTR in epithelial cells is still unknown. In the present work, we describe experiments to define the interactions between CFTR and NHE3 with the regulatory, scaffolding protein, NHERF that organize their PKA-dependent regulation in a renal epithelial cell line that expresses endogenous CFTR. The expression of rat NHE3 significantly decreased PKAdependent activation of CFTR without altering CFTR expression, and this decrease was prevented by mutation of either of the two rat NHE3 PKA target serines to alanine (S552A or S605A). Inhibition of CFTR expression by antisense treatment resulted in an acute decrease in PKA-dependent regulation of NHE3 activity. CFTR, NHE3, and ezrin were recognized by NHERF-2 but not NHERF-1 in glutathione S-transferase pull-down experiments. Ezrin may function as a protein kinase A anchoring protein (AKAP) in this signaling complex, because blocking the binding of PKA to an AKAP by incubation with the S-Ht31 peptide inhibited the PKAdependent regulation of CFTR in the absence of NHE3. In the A6-NHE3 cells S-Ht31 blocked the PKA regulation of NHE3 whereas it now failed to affect the regulation of CFTR. We conclude that CFTR and NHE3 reciprocally interact via a shared regulatory complex comprised of NHERF-2, ezrin, and PKA.

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“…Although in most cases the receptor subtype was identified from the signal transduction pathway without a functional role being determined, some studies have linked function with specific receptors. Some examples include a basolateral A 1 receptor in rabbit inner medullary collecting duct cells that inhibits the action of vasopressin (11), an apical A 1 receptor that stimulates Ca 2ϩ absorption in cultured rabbit cortical collecting system cells (16), and adenosine stimulation of the Na-K-Cl cotransporter in A6 cells from ATCC (13).…”

Section: Discussionmentioning

confidence: 99%

Basolateral and apical A₁ adenosine receptors mediate sodium transport in cultured renal epithelial (A6) cells

Macala

Hayslett

2002

American Journal of Physiology-Renal Physiology

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There are conflicting reports in the literature regarding the adenosine receptor that mediates the increase in sodium transport in the A6 cell. In this study we used specific A1 and A2 adenosine receptor agonists and antagonists, as well as two different subclones of the A6 cell, to determine which adenosine receptor mediates the increase in sodium transport. In the A6S2 subclone, basolateral and apical N6-cyclohexyladenosine (CHA), a selective A1 receptor agonist, stimulated sodium transport at a threshold concentration <10(-7) M, whereas CGS-21680, a selective A2 receptor agonist, had a threshold concentration that was at least 10(-5) M. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) was found to have a nonspecific effect on CHA-stimulated sodium transport, whereas the A2 receptor antagonist 8-(3-chlorostyryl)caffeine (CSC) had no effect. As with the A6S2 subclone, basolateral and apical CHA stimulated sodium transport at a nanomolar concentration in the A6C1 subclone and the threshold concentration for CGS-21680 was in the high micromolar range. Concurrent with the increase in 1 receptor in different subclones of the A6 cell, including a subclone capable of anion secretion.

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Identification of a regulated Na/K/Cl cotransport system in a distal nephron cell line

Cited by 11 publications

References 29 publications

SGK1 activates Na⁺-K⁺-ATPase in amphibian renal epithelial cells

SGK1 activates Na⁺-K⁺-ATPase in amphibian renal epithelial cells

Reciprocal Protein Kinase A Regulatory Interactions between Cystic Fibrosis Transmembrane Conductance Regulator and Na+/H+ Exchanger Isoform 3 in a Renal Polarized Epithelial Cell Model

Basolateral and apical A₁ adenosine receptors mediate sodium transport in cultured renal epithelial (A6) cells

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Identification of a regulated Na/K/Cl cotransport system in a distal nephron cell line

Cited by 11 publications

References 29 publications

SGK1 activates Na+-K+-ATPase in amphibian renal epithelial cells

SGK1 activates Na+-K+-ATPase in amphibian renal epithelial cells

Reciprocal Protein Kinase A Regulatory Interactions between Cystic Fibrosis Transmembrane Conductance Regulator and Na+/H+ Exchanger Isoform 3 in a Renal Polarized Epithelial Cell Model

Basolateral and apical A1 adenosine receptors mediate sodium transport in cultured renal epithelial (A6) cells

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SGK1 activates Na⁺-K⁺-ATPase in amphibian renal epithelial cells

SGK1 activates Na⁺-K⁺-ATPase in amphibian renal epithelial cells

Basolateral and apical A₁ adenosine receptors mediate sodium transport in cultured renal epithelial (A6) cells