TY  - JOUR
A1  - Mutig, Kerim
A1  - Kahl, Thomas
A1  - Saritas, Turgay
A1  - Godes, Michael
A1  - Persson, Pontus
A1  - Bates, James
A1  - Raffi, Hajamohideen
A1  - Rampoldi, Luca
A1  - Uchida, Shinichi
A1  - Hille, Carsten
A1  - Dosche, Carsten
A1  - Kumar, Satish
A1  - Castaneda-Bueno, Maria
A1  - Gamba, Gerardo
A1  - Bachmann, Sebastian
T1  - Activation of the Bumetanide-sensitive Na+, K+,2Cl(-) Cotransporter (NKCC2) Is Facilitated by Tamm-Horsfall Protein in a Chloride-sensitive Manner
JF  - The journal of biological chemistry
N2  - Active transport of NaCl across thick ascending limb (TAL) epithelium is accomplished by Na+, K+,2Cl(-) cotransporter (NKCC2). The activity of NKCC2 is determined by vasopressin (AVP) or intracellular chloride concentration and includes its amino-terminal phosphorylation. Co-expressed Tamm-Horsfall protein (THP) has been proposed to interact with NKCC2. We hypothesized that THP modulates NKCC2 activity in TAL. THP-deficient mice (THP-/-) showed an increased abundance of intracellular NKCC2 located in subapical vesicles (+47% compared with wild type (WT) mice), whereas base-line phosphorylation of NKCC2 was significantly decreased (-49% compared with WT mice), suggesting reduced activity of the transporter in the absence of THP. Cultured TAL cells with low endogenous THP levels and low base-line phosphorylation of NKCC2 displayed sharp increases in NKCC2 phosphorylation (+38%) along with a significant change of intracellular chloride concentration upon transfection with THP. In NKCC2-expressing frog oocytes, co-injection with THP cRNA significantly enhanced the activation of NKCC2 under low chloride hypotonic stress (+112% versus +235%). Short term (30 min) stimulation of the vasopressin V2 receptor pathway by V2 receptor agonist (deamino-cis-D-Arg vasopressin) resulted in enhanced NKCC2 phosphorylation in WT mice and cultured TAL cells transfected with THP, whereas in the absence of THP, NKCC2 phosphorylation upon deamino-cis-D-Arg vasopressin was blunted in both systems. Attenuated effects of furosemide along with functional and structural adaptation of the distal convoluted tubule in THP-/- mice supported the notion that NaCl reabsorption was impaired in TAL lacking THP. In summary, these results are compatible with a permissive role for THP in the modulation of NKCC2-dependent TAL salt reabsorptive function.
Y1  - 2011
U6  - https://doi.org/10.1074/jbc.M111.222968
SN  - 0021-9258
VL  - 286
IS  - 34
SP  - 30200
EP  - 30210
PB  - American Society for Biochemistry and Molecular Biology
CY  - Bethesda
ER  -