TY - JOUR
T1 - Intracellular trafficking of a polymorphism in the COOH terminus of the α-subunit of the human epithelial sodium channel is modulated by casein kinase 1
AU - Yan, Wusheng
AU - Spruce, Lynn
AU - Rosenblatt, Michael M.
AU - Kleyman, Thomas R.
AU - Rubenstein, Ronald C.
PY - 2007/9
Y1 - 2007/9
N2 - The A663T polymorphism of the α-subunit of the human epithelial sodium channel (hENaC) increases the functional and surface expression of αβγ-hENaC in Xenopus laevis oocytes, and the context of this residue in the COOH terminus of α-hENaC is important for this effect. Query of a phosphoprotein database suggested that the α-T663 residue of hENaC might be a substrate for phosphorylation by casein kinase 1 (CK1). We tested the hypotheses that phosphorylation of α-T663-hENaC by CK1 would regulate the increased functional and surface expression of α-T663-hENaC vs. α-A663-hENaC in oocytes. General inhibition of CK1 with IC261 decreased the functional and surface expression of α-T663-hENaC, but not α-A663-hENaC. This decrease in α-T663-hENaC functional expression resulted from reduced delivery of α-T663-hENaC to the oocyte membrane. IC261 also inhibited the functional expression of α-T692-mENaC and a chimeric m(1-678)/h(650-669)α-T663, mβγ ENaC, but not α-A692-mENaC or m(1-678)/h(650-669)α-A663, mβγ ENaC. These data suggest that additional residues outside of the α-hENaC COOH terminus are important for modulation of α-T663-hENaC trafficking by CK1. Overexpression of CK1α did not alter functional expression of α-T663-hENaC. In contrast, modest overexpression of CK1δ enhanced, whereas higher levels of CK1δ overexpression inhibited α-T663-hENaC functional expression. CK1 did not phosphorylate the COOH terminus of either α-T663-hENaC or α-A663-hENaC in vitro. These data suggest that CK1, and perhaps specifically CK1δ, regulates the intracellular trafficking of the α-A663T functional polymorphism of hENaC indirectly by altering the rate of α-T663-hENaC biosynthesis and/or delivery to the plasma membrane.
AB - The A663T polymorphism of the α-subunit of the human epithelial sodium channel (hENaC) increases the functional and surface expression of αβγ-hENaC in Xenopus laevis oocytes, and the context of this residue in the COOH terminus of α-hENaC is important for this effect. Query of a phosphoprotein database suggested that the α-T663 residue of hENaC might be a substrate for phosphorylation by casein kinase 1 (CK1). We tested the hypotheses that phosphorylation of α-T663-hENaC by CK1 would regulate the increased functional and surface expression of α-T663-hENaC vs. α-A663-hENaC in oocytes. General inhibition of CK1 with IC261 decreased the functional and surface expression of α-T663-hENaC, but not α-A663-hENaC. This decrease in α-T663-hENaC functional expression resulted from reduced delivery of α-T663-hENaC to the oocyte membrane. IC261 also inhibited the functional expression of α-T692-mENaC and a chimeric m(1-678)/h(650-669)α-T663, mβγ ENaC, but not α-A692-mENaC or m(1-678)/h(650-669)α-A663, mβγ ENaC. These data suggest that additional residues outside of the α-hENaC COOH terminus are important for modulation of α-T663-hENaC trafficking by CK1. Overexpression of CK1α did not alter functional expression of α-T663-hENaC. In contrast, modest overexpression of CK1δ enhanced, whereas higher levels of CK1δ overexpression inhibited α-T663-hENaC functional expression. CK1 did not phosphorylate the COOH terminus of either α-T663-hENaC or α-A663-hENaC in vitro. These data suggest that CK1, and perhaps specifically CK1δ, regulates the intracellular trafficking of the α-A663T functional polymorphism of hENaC indirectly by altering the rate of α-T663-hENaC biosynthesis and/or delivery to the plasma membrane.
KW - Phosphorylation
KW - Xenopus laevis oocytes
UR - http://www.scopus.com/inward/record.url?scp=34548624321&partnerID=8YFLogxK
U2 - 10.1152/ajprenal.00194.2007
DO - 10.1152/ajprenal.00194.2007
M3 - Article
C2 - 17596527
AN - SCOPUS:34548624321
SN - 1931-857X
VL - 293
SP - F868-F876
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 3
ER -