Functional interaction of COMMD3 and COMMD9 with the epithelial sodium channel

The epithelial sodium channel (ENaC) plays an important role in controlling Na+ homeostasis, extracellular fluid volume, and blood pressure. Copper metabolism Murr1 domain-containing protein 1 (COMMD1) interacts with ENaC and downregulates ENaC. COMMD1 belongs to the COMMD family consisting of COMMD1–10, and all COMMD family members share a C-terminal COMM domain. Here, we report that COMMD2–10 also interacts with ENaC, and COMMD3 and COMMD9 were selected for further study. Amiloride-sensitive current in mammalian epithelia expressing ENaC was significantly reduced by COMMD3 or COMMD9, and ENaC expression at the cell surface was significantly decreased in the presence of COMMD3 or COMMD9. COMMD3 and COMMD9 retained their ability to reduce current when COMMD1 was knocked down. COMMD3 and COMMD9 were widely expressed in kidney and were colocalized with ENaC in renal collecting duct cells. These data suggest that COMMD3 and COMMD9 may be endogenous regulators of ENaC to regulate Na+ transport through altering ENaC cell surface expression.

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Phosphatidylinositol 4-Phosphate 5-Kinase Reduces Cell Surface Expression of the Epithelial Sodium Channel (ENaC) in Cultured Collecting Duct Cells

Journal of Biological Chemistry ◽

10.1074/jbc.m703970200 ◽

2007 ◽

Vol 282 (50) ◽

pp. 36534-36542 ◽

Cited By ~ 24

Author(s):

Kelly M. Weixel ◽

Robert S. Edinger ◽

Lauren Kester ◽

Christopher J. Guerriero ◽

Huamin Wang ◽

...

Keyword(s):

Cell Surface ◽

Sodium Channel ◽

Collecting Duct ◽

Epithelial Sodium Channel ◽

Surface Expression ◽

Cell Surface Expression ◽

Duct Cells ◽

Collecting Duct Cells ◽

Phosphatidylinositol 4 ◽

Epithelial Sodium Channel Enac

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COMMD1 downregulates the epithelial sodium channel through Nedd4–2

AJP Renal Physiology ◽

10.1152/ajprenal.00257.2009 ◽

2010 ◽

Vol 298 (6) ◽

pp. F1445-F1456 ◽

Cited By ~ 32

Author(s):

Ying Ke ◽

A. Grant Butt ◽

Marianne Swart ◽

Yong Feng Liu ◽

Fiona J. McDonald

Keyword(s):

Epithelial Cells ◽

Cell Surface ◽

Sodium Channel ◽

Rat Kidney ◽

Copper Metabolism ◽

Epithelial Sodium Channel ◽

Surface Expression ◽

Dominant Negative ◽

Cell Surface Expression ◽

Xenopus Laevis Oocytes

The epithelial sodium channel (ENaC) is important for the long-term control of Na+ homeostasis and blood pressure. Our previous studies demonstrated that Copper Metabolism Murr1 Domain-containing protein 1 (COMMD1; previously known as Murr1), a protein involved in copper metabolism, inhibited amiloride-sensitive current in Xenopus laevis oocytes expressing ENaC ( J Biol Chem 279: 5429, 2004). In this study, we report that COMMD1 inhibits amiloride-sensitive current in mammalian epithelial cells expressing ENaC, that the COMM domain of COMMD1 is sufficient for this effect, and that knockdown of COMMD1 increases amiloride-sensitive current. COMMD1 is coexpressed with ENaC in rat kidney medulla cells. COMMD1 increased ubiquitin modification of ENaC and decreased its cell surface expression. COMMD1 abolished insulin-stimulated amiloride-sensitive current and attenuated the stimulation of current by activated serum and glucocorticoid-regulated kinase (SGK1). COMMD1 was found to interact with both SGK1 and Akt1/protein kinase B, and knockdown of COMMD1 enhanced the stimulatory effect of both SGK1 and Akt1 on amiloride-sensitive current. COMMD1's effects were reduced in the presence of ENaC proteins containing PY motif mutations, abolished in the presence of a dominant negative form of Nedd4–2, and knockdown of COMMD1 reduced the inhibitory effect of Nedd4–2 on ENaC, but did not enhance current when Nedd4–2 was knocked down. These data suggest that COMMD1 modulates Na+ transport in epithelial cells through regulation of ENaC cell surface expression and this effect is likely mediated via Nedd4–2.

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Nedd4-2 isoforms ubiquitinate individual epithelial sodium channel subunits and reduce surface expression and function of the epithelial sodium channel

AJP Renal Physiology ◽

10.1152/ajprenal.00339.2007 ◽

2008 ◽

Vol 294 (5) ◽

pp. F1157-F1165 ◽

Cited By ~ 22

Author(s):

Nandita S. Raikwar ◽

Christie P. Thomas

Keyword(s):

Cell Surface ◽

Sodium Channel ◽

Collecting Duct ◽

Epithelial Sodium Channel ◽

Surface Expression ◽

Cell Surface Expression ◽

Membrane Expression ◽

Ww Domains ◽

Ubiquitin Proteasome ◽

And Function

We previously reported the existence of multiple isoforms of human Nedd4-2 ( Am J Physiol Renal Physiol 285: F916–F929, 2003). When overexpressed in M-1 collecting duct epithelia, full-length Nedd4-2 (Nedd4-2), Nedd4-2 lacking the NH2-terminal C2 domain (Nedd4-2ΔC2), and Nedd4-2 lacking WW domains 2 and 3 (Nedd4-2ΔWW2,3) variably reduce benzamil-sensitive Na+ transport. We investigated the effect of each of the Nedd4-2 isoforms on cell surface expression and ubiquitination of ENaC subunits. We find that αENaC when transfected alone or with β and γENaC is expressed at the cell surface and this membrane expression is variably reduced by coexpression with each of the Nedd4-2 isoforms. Nedd4-2 reduces the half-life of ENaC subunits and enhances the ubiquitination of α, β, and γENaC subunits when expressed alone or together suggesting that each subunit is a target for Nedd4-2-mediated ubiquitination. As has been reported recently, we confirm that the surface-expressed pool of ENaC is multi-ubiquitinated. Inhibitors of the proteasome increase ubiquitination of ENaC subunits and stimulate Na+ transport in M-1 cells consistent with a role for the ubiquitin-proteasome pathway in regulating Na+ transport in the collecting duct.

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Intracellular Na+ Controls Cell Surface Expression of Na,K-ATPase via a cAMP-independent PKA Pathway in Mammalian Kidney Collecting Duct Cells

Molecular Biology of the Cell ◽

10.1091/mbc.e02-11-0720 ◽

2003 ◽

Vol 14 (7) ◽

pp. 2677-2688 ◽

Cited By ~ 49

Author(s):

Manlio Vinciguerra ◽

Georges Deschênes ◽

Udo Hasler ◽

David Mordasini ◽

Martine Rousselot ◽

...

Keyword(s):

Cell Membrane ◽

Cell Surface ◽

Atpase Activity ◽

Collecting Duct ◽

Surface Expression ◽

Cell Surface Expression ◽

Cortical Collecting Duct ◽

Mammalian Kidney ◽

Duct Cells ◽

Collecting Duct Cells

In the mammalian kidney the fine control of Na+ reabsorption takes place in collecting duct principal cells where basolateral Na,K-ATPase provides the driving force for vectorial Na+ transport. In the cortical collecting duct (CCD), a rise in intracellular Na+ concentration ([Na+]i) was shown to increase Na,K-ATPase activity and the number of ouabain binding sites, but the mechanism responsible for this event has not yet been elucidated. A rise in [Na+]i caused by incubation with the Na+ ionophore nystatin, increased Na,K-ATPase activity and cell surface expression to the same extent in isolated rat CCD. In cultured mouse mpkCCDcl4 collecting duct cells, increasing [Na+]i either by cell membrane permeabilization with amphotericin B or nystatin, or by incubating cells in a K+-free medium, also increased Na,K-ATPase cell surface expression. The [Na+]i-dependent increase in Na,K-ATPase cell-surface expression was prevented by PKA inhibitors H89 and PKI. Moreover, the effects of [Na+]i and cAMP were not additive. However, [Na+]i-dependent activation of PKA was not associated with an increase in cellular cAMP but was prevented by inhibiting the proteasome. These findings suggest that Na,K-ATPase may be recruited to the cell membrane following an increase in [Na+]i through cAMP-independent PKA activation that is itself dependent on proteasomal activity.

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