Regulation of Renal Na+/HCO3− Cotransporter Stimulation by CO2: Role of Phosphorylation, Exocytosis and Protein Synthesis

Espiritu, Doris Joy D.; Yang, VW; Bernardo, Angelito; Arruda, José A.L.

doi:10.1007/s00232-004-0675-x

Cited by 10 publications

(7 citation statements)

References 24 publications

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“…Additional possible regulatory mechanisms are the formation of a regulatory complex with adapter proteins or vesicle traffic. Arruda and collegues (7,53) have reported an interaction of PDZ domain-binding proteins with renal NBC; furthermore, subcellular redistribution and changes in cell surface expression, which are important for many ion transport processes, have been found to regulate renal NBC (13). Whether these mechanisms are involved in intestinal NBC regulation requires further investigation.…”

Section: Discussionmentioning

confidence: 94%

Carbachol increases Na⁺-HCO₃⁻ cotransport activity in murine colonic crypts in a M₃⁻, Ca²⁺/calmodulin-, and PKC-dependent manner

Bachmann

Reichelt²,

Tuo³

et al. 2006

American Journal of Physiology-Gastrointestinal and Liver Physi

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The Na(+)-HCO(3)(-) cotransporter (NBC) mediates HCO(3)(-) import into the colonocyte via its pNBC1 isoform. Whereas renal kNBC1 is inhibited by increased cAMP levels, pNBC1 is stimulated. Cholinergic stimulation activates renal NBC, but the effect on intestinal NBC is unknown. Therefore, crypts were isolated from the murine proximal colon by Ca(2+) chelation and loaded with the pH-sensitive dye 2',7'-bis-carboxyethyl-5,6-carboxyfluorescein. Na(+)-HCO(3)(-) cotransport activity was calculated from the dimethylamiloride-insensitive (500 microM) intracellular pH recovery from an acid load in the presence of CO(2)-HCO(3)(-) and the intracellular buffering capacity. Carbachol strongly increased Na(+)-HCO(3)(-) cotransport activity compared with control rates. Ca(2+) chelation with BAPTA-AM, blockade of the M(3) subtype of muscarinergic receptors with 4-diphenylacetoxy-N-methylpiperidine methiodide, and inhibition of Ca(2+)/calmodulin kinase II with KN-62 all caused significant inhibition of the carbachol-induced NBC activity increase. Furthermore, PKC inhibition with Gö-6976 and Gö-6850 significantly reduced the carbachol effect, which may be related to the unique NH(2)-terminal consensus site for PKC-dependent phosphorylation of pNBC1. We conclude that NBC in the murine colon is thus activated by carbachol, consistent with its presumed function as an anion uptake pathway during intestinal anion secretion, but that the signal transductions pathways are distinct from those involved in the cholinergic activation of renal NBC1.

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Section: Discussionmentioning

confidence: 94%

Carbachol increases Na⁺-HCO₃⁻ cotransport activity in murine colonic crypts in a M₃⁻, Ca²⁺/calmodulin-, and PKC-dependent manner

Bachmann

Reichelt²,

Tuo³

et al. 2006

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…In summary, in chronic respiratory acidosis, the proximal tubule seems to participate in renal compensation by increasing its absorption of bicarbonate through activation and increased expression of NBCe1, and activation of NHE3 independently of protein expression (5,9,32,39).…”

Section: Discussionmentioning

confidence: 99%

Renal compensation to chronic hypoxic hypercapnia: downregulation of pendrin and adaptation of the proximal tubule

Seigneux¹,

Malte²,

Dimke³

et al. 2007

American Journal of Physiology-Renal Physiology

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December 19, 2006; doi:10.1152/ajprenal.00220.2006.-The molecular basis for the renal compensation to respiratory acidosis and specifically the role of pendrin in this condition are unclear. Therefore, we studied the adaptation of the proximal tubule and the collecting duct to respiratory acidosis. Male Wistar-Hannover rats were exposed to either hypercapnia and hypoxia [8% CO 2 and 13% O 2 (hypercapnic, n ϭ 6) or normal air (controls, n ϭ 6)] in an environmental chamber for 10 days and were killed under the same atmosphere. In hypercapnic rats, arterial pH was lower than controls (7.31 Ϯ 0.01 vs. 7.39 Ϯ 0.01, P ϭ 0.03), blood HCO 3 Ϫ concentration was increased (42 Ϯ 0.9 vs. 32 Ϯ 0.24 mM, P Ͻ 0.001), arterial PCO 2 was increased (10.76 Ϯ 0.4 vs. 7.20 Ϯ 0.4 kPa, P Ͻ 0.001), and plasma chloride concentration was decreased (92.2 Ϯ 0.7 vs. 97.2 Ϯ 0.5 mM, P Ͻ 0.001). Plasma aldosterone levels were unchanged. In the proximal tubule, immunoblotting showed an increased expression of sodium/bicarbonate exchanger protein (188 Ϯ 22 vs. 100 Ϯ 11%, P ϭ 0.005), confirmed by immunohistochemistry. Total Na/H exchanger protein expression in the cortex was unchanged by immunoblotting (119 Ϯ 10 vs. 100 Ϯ 11%, P ϭ 0.27) and immunohistochemistry. In the cortex, the abundance of pendrin was decreased (51 Ϯ 9 vs. 100 Ϯ 7%, P ϭ 0.003) by immunoblotting. Immunohistochemistry revealed that this decrease was clear in both cortical collecting ducts (CCDs) and connecting tubules (CNTs). This demonstrates that pendrin expression can be regulated in acidotic animals with no changes in aldosterone levels and no external chloride load. This reduction of pendrin expression may help in redirecting the CNT and CCD toward chloride excretion and bicarbonate reabsorption, contributing to the increased plasma bicarbonate and decreased plasma chloride of chronic respiratory acidosis.

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“…Twenty-four hours after transfection, cells were labeled with sulfo-NHS-LC-biotin, as described by Sargiacomo et al (25), with some modifications. This technique has been extensively used for measuring basolateral or apical membrane expression (6,9,36). In brief, cells were washed with PBS (pH 7.4) and labeled with 0.5 mg/ml sulfo-NHS-LC-biotin in PBS containing Ca 2ϩ /Mg 2ϩ for 25 min at 4°C.…”

Section: Methodsmentioning

confidence: 99%

“…The amount of endocytosed NBC1 was measured using 2-mercaptoethanesulfonic acid sodium salt (mesna) as previously described (6,36). Mesna is a cell-impermeant agent capable of disrupting biotin-protein binding.…”

Section: Methodsmentioning

confidence: 99%

Role of NH₂ and COOH termini in targeting, stability, and activity of sodium bicarbonate cotransporter 1

Espiritu

Bernardo²,

Arruda³

2006

American Journal of Physiology-Renal Physiology

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Sodium bicarbonate cotransporter 1 (NBC1) mediates 80% of bicarbonate reabsorption by the kidney, but the molecular determinants for activity, targeting, and cell membrane stability are poorly understood. We generated truncation mutants involving the entire NH2 (⌬N424) or the entire COOH (⌬C92) terminus and examined the effects of these truncations on targeting, cell membrane stability, and NBC1 activity. ⌬N424 and ⌬C92 targeted to the plasma membrane of HEK293 cells or to the basolateral membrane of opossum kidney (OK) cells at 24 h but did not display NBC1 activity. Unlike the NBC1 wild-type and the ⌬N424, ⌬C92 expression was significantly decreased in the basolateral membrane at 48 h and yet the total ⌬C92 expression in the cell was constant. We found that decreased ⌬C92 expression in the basolateral membrane was due to increased endocytosis and mistargeting to the apical membrane. Increased endocytosis was prevented when both ⌬N424 and ⌬C92 were cotransfected together and more stable expression of ⌬C92 was observed. Immunoprecipitation studies using NBC1 antibody specific for the COOH epitope were able to detect the COOH truncated NBC1 when probed with NH2 epitope-specific antibody or vice versa. Similar findings were observed with Ni-NTA pull-down assay. Cotransfection of both mutants partially restored NBC1 activity. In summary, NBC1 targets to the basolateral membrane of OK cells by a default mechanism and the COOH terminus plays a role on NBC1 stability in the basolateral membrane. endocytosis; basolateral membrane; apical membrane; protein-protein interaction THE SODIUM BICARBONATE COTRANSPORTER (NBC1) mediates bicarbonate reabsorption in the renal proximal tubule and is important for pH regulation in different cell types (2, 3, 21). Acute and chronic regulations of NBC1 have been studied extensively (7,18,22,23). However, the molecular determinants necessary for understanding NBC1 activity in normal and disease states are not known.NBC1 is localized in the basolateral membrane of the renal proximal tubule cells. NBC1 has 10 transmembrane-spanning domains with a long NH 2 and a short COOH terminus located intracellularly (31). Previous studies of other members of the bicarbonate superfamily, anion exchangers (AEs), have provided insights into the role of the NH 2 and the COOH termini on structure and function of the exchangers (14,28,33,37,39). In these studies, the NH 2 and COOH termini play an important role in regulation, localization, dimerization, and function of AEs. The NH 2 terminus of NBC1 contains conserved amino acids found in anion exchanger 2 (AE2) necessary for pH sensing (28) and contains a stretch of conserved amino acids found in AE1 necessary for activity (14). The NH 2 terminus of AE1 is also necessary for interaction with other cytoplasmic loops of AE1 in erythrocytes (14). Furthermore, crystallographic structure analysis of the NH 2 terminus of AE1 showed that its NH 2 terminus is important for cytoskeletal protein binding and dimerization (37) and is necessary for membrane insertio...

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Regulation of Renal Na+/HCO3− Cotransporter Stimulation by CO2: Role of Phosphorylation, Exocytosis and Protein Synthesis

Cited by 10 publications

References 24 publications

Carbachol increases Na⁺-HCO₃⁻ cotransport activity in murine colonic crypts in a M₃⁻, Ca²⁺/calmodulin-, and PKC-dependent manner

Carbachol increases Na⁺-HCO₃⁻ cotransport activity in murine colonic crypts in a M₃⁻, Ca²⁺/calmodulin-, and PKC-dependent manner

Renal compensation to chronic hypoxic hypercapnia: downregulation of pendrin and adaptation of the proximal tubule

Role of NH₂ and COOH termini in targeting, stability, and activity of sodium bicarbonate cotransporter 1

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Regulation of Renal Na+/HCO3− Cotransporter Stimulation by CO2: Role of Phosphorylation, Exocytosis and Protein Synthesis

Cited by 10 publications

References 24 publications

Carbachol increases Na+-HCO3− cotransport activity in murine colonic crypts in a M3−, Ca2+/calmodulin-, and PKC-dependent manner

Carbachol increases Na+-HCO3− cotransport activity in murine colonic crypts in a M3−, Ca2+/calmodulin-, and PKC-dependent manner

Renal compensation to chronic hypoxic hypercapnia: downregulation of pendrin and adaptation of the proximal tubule

Role of NH2 and COOH termini in targeting, stability, and activity of sodium bicarbonate cotransporter 1

Contact Info

Product

Resources

About

Carbachol increases Na⁺-HCO₃⁻ cotransport activity in murine colonic crypts in a M₃⁻, Ca²⁺/calmodulin-, and PKC-dependent manner

Carbachol increases Na⁺-HCO₃⁻ cotransport activity in murine colonic crypts in a M₃⁻, Ca²⁺/calmodulin-, and PKC-dependent manner

Role of NH₂ and COOH termini in targeting, stability, and activity of sodium bicarbonate cotransporter 1