TY - JOUR
T1 - Calcineurin and Sorting-Related Receptor with A-Type Repeats Interact to Regulate the Renal Na+-K+-2Cl- Cotransporter
AU - Borschewski, Aljona
AU - Himmerkus, Nina
AU - Boldt, Christin
AU - Blankenstein, Katharina I.
AU - McCormick, James A.
AU - Lazelle, Rebecca
AU - Willnow, Thomas E.
AU - Jankowski, Vera
AU - Plain, Allein
AU - Bleich, Markus
AU - Ellison, David H.
AU - Bachmann, Sebastian
AU - Mutig, Kerim
N1 - Publisher Copyright:
© 2016 by the American Society of Nephrology.
PY - 2016/1
Y1 - 2016/1
N2 - The furosemide-sensitive Na+-K+-2Cl--cotransporter (NKCC2) is crucial for NaCl reabsorption in kidney thick ascending limb (TAL) and drives the urine concentrating mechanism. NKCC2 activity ismodulated by N-terminal phosphorylation and dephosphorylation. Serine-threonine kinases that activate NKCC2 have been identified, but less is known about phosphatases that deactivate NKCC2. Inhibition of calcineurin phosphatase has been shown to stimulate transport in the TAL and the distal convoluted tubule. Here, we identified NKCC2 as a target of the calcineurin Aβ isoform. Short-term cyclosporine administration inmice augmented the abundance of phospho-NKCC2, and treatment of isolated TAL with cyclosporine increased the chloride affinity and transport activity of NKCC2. Because sorting-related receptor with Atype repeats (SORLA) may affect NKCC2 phosphoregulation, we used SORLA-knockout mice to test whether SORLA is involved in calcineurin-dependent modulation of NKCC2. SORLA-deficient mice showed more calcineurin Aβ in the apical region of TAL cells and less NKCC2 phosphorylation and activity compared with littermate controls. In contrast, overexpression of SORLA in cultured cells reduced the abundance of endogenous calcineurin Aβ. Cyclosporine administration rapidly normalized the abundance of phospho-NKCC2 in SORLA-deficientmice, and a functional interaction between calcineurin Aβ and SORLAwas further corroborated by binding assays in rat kidney extracts. In summary, we have shown that calcineurin Aβ and SORLA are key components in the phosphoregulation of NKCC2. These results may have clinical implications for immunosuppressive therapy using calcineurin inhibitors.
AB - The furosemide-sensitive Na+-K+-2Cl--cotransporter (NKCC2) is crucial for NaCl reabsorption in kidney thick ascending limb (TAL) and drives the urine concentrating mechanism. NKCC2 activity ismodulated by N-terminal phosphorylation and dephosphorylation. Serine-threonine kinases that activate NKCC2 have been identified, but less is known about phosphatases that deactivate NKCC2. Inhibition of calcineurin phosphatase has been shown to stimulate transport in the TAL and the distal convoluted tubule. Here, we identified NKCC2 as a target of the calcineurin Aβ isoform. Short-term cyclosporine administration inmice augmented the abundance of phospho-NKCC2, and treatment of isolated TAL with cyclosporine increased the chloride affinity and transport activity of NKCC2. Because sorting-related receptor with Atype repeats (SORLA) may affect NKCC2 phosphoregulation, we used SORLA-knockout mice to test whether SORLA is involved in calcineurin-dependent modulation of NKCC2. SORLA-deficient mice showed more calcineurin Aβ in the apical region of TAL cells and less NKCC2 phosphorylation and activity compared with littermate controls. In contrast, overexpression of SORLA in cultured cells reduced the abundance of endogenous calcineurin Aβ. Cyclosporine administration rapidly normalized the abundance of phospho-NKCC2 in SORLA-deficientmice, and a functional interaction between calcineurin Aβ and SORLAwas further corroborated by binding assays in rat kidney extracts. In summary, we have shown that calcineurin Aβ and SORLA are key components in the phosphoregulation of NKCC2. These results may have clinical implications for immunosuppressive therapy using calcineurin inhibitors.
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U2 - 10.1681/ASN.2014070728
DO - 10.1681/ASN.2014070728
M3 - Article
C2 - 25967121
AN - SCOPUS:84954447669
SN - 1046-6673
VL - 27
SP - 107
EP - 119
JO - Journal of the American Society of Nephrology
JF - Journal of the American Society of Nephrology
IS - 1
ER -