Molecular mechanisms and regulation of furosemide-sensitive Na–K–Cl cotransporters

Gíménez, Ignacio

doi:10.1097/01.mnh.0000242178.44576.b0

Cited by 71 publications

(49 citation statements)

References 50 publications

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“…The transport activity of NKCC1 depends on the phosphorylation of four threonine residues in its N terminus , and Thr-208 in rat NKCC1). The kinases that mediate NKCC1 phosphorylation are SPAK and OSR1, both members of the germinal center kinase (GCK)-VI subfamily (9,12,(36)(37)(38). Both kinases are regulated by the WNK family of protein kinases (10).…”

Section: Discussionmentioning

confidence: 99%

“…We next asked which protein kinases are involved in upholding this high level of phosphorylation. NKCC1 is a substrate for the two protein kinases SPAK and OSR1 (9,12). These kinases are themselves activated by the protein kinases WNK1 and WNK4 (10), which therefore participate indirectly in the control of NKCC1 activity.…”

Section: Nkcc1 Expressionmentioning

confidence: 99%

“…As the activity of NKCC1 depends on phosphorylation (12)(13)(14), we sought to estimate the degree of NKCC1 phosphorylation in olfactory cilia. The polyclonal antiserum S763B contains antibodies specific for the phosphorylated form of NKCC1 (pNKCC1) and antibodies that bind to nonphosphorylated NKCC1.…”

Section: Nkcc1 Expressionmentioning

confidence: 99%

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Molecular components of signal amplification in olfactory sensory cilia

Hengl

Kaneko

Dauner

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

102

100

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The mammalian olfactory system detects an unlimited variety of odorants with a limited set of odorant receptors. To cope with the complexity of the odor world, each odorant receptor must detect many different odorants. The demand for low odor selectivity creates problems for the transduction process: the initial transduction step, the synthesis of the second messenger cAMP, operates with low efficiency, mainly because odorants bind only briefly to their receptors. Sensory cilia of olfactory receptor neurons have developed an unusual solution to this problem. They accumulate chloride ions at rest and discharge a chloride current upon odor detection. This chloride current amplifies the receptor potential and promotes electrical excitation. We have studied this amplification process by examining identity, subcellular localization, and regulation of its molecular components. We found that the Na + /K + /2Cl − cotransporter NKCC1 is expressed in the ciliary membrane, where it mediates chloride accumulation into the ciliary lumen. Gene silencing experiments revealed that the activity of this transporter depends on the kinases SPAK and OSR1, which are enriched in the cilia together with their own activating kinases, WNK1 and WNK4. A second Cl − transporter, the Cl − /HCO 3 − exchanger SLC4A1, is expressed in the cilia and may support Cl − accumulation. The calcium-dependent chloride channel TMEM16B (ANO2) provides a ciliary pathway for the excitatory chloride current. These findings describe a specific set of ciliary proteins involved in anion-based signal amplification. They provide a molecular concept for the unique strategy that allows olfactory sensory neurons to operate as efficient transducers of weak sensory stimuli.chloride | olfaction | sensory transduction | transport | kinase M ammalian olfactory receptor neurons (ORNs) present to the air a tuft of sensory cilia equipped with odorant receptors. Upon contact with odorants, these receptors actuate a transduction cascade that leads to firing of action potentials. This cascade has an unusual, two-stage organization (1). First, the activated odorant receptors induce a rise of the second messengers cAMP and Ca 2+ in the cilia, a process that involves cAMP-gated, Ca 2+ -permeable ion channels. In the second stage, inflowing Ca 2+ opens Cl − channels. By conducting a depolarizing Cl − efflux from the cilia, these channels amplify the receptor potential approximately 10-fold, thus helping to excite the neuron even when stimulation is weak. ORNs accumulate chloride through the Na + /K + /2Cl − cotransporter NKCC1 and maintain an elevated intracellular Cl − concentration (2, 3) to support amplification. Accordingly, gene ablation of NKCC1, as well as the pharmacologic suppression of Cl − accumulation or Cl − efflux, strongly inhibits the sensory response of ORNs (3-5). Although these observations provide a robust concept for signal amplification, several points are still unclear. These concern both the Cl − accumulation process and the excitatory Cl − currents. First, ...

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Section: Discussionmentioning

confidence: 99%

Section: Nkcc1 Expressionmentioning

confidence: 99%

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Molecular components of signal amplification in olfactory sensory cilia

Hengl

Kaneko

Dauner

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

102

100

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“…The overall process of salt and fluid secretion in Cl -secretory epithelia is generally stimulated by cAMP-dependent processes; investigations have supported a model in which cAMP stimulates PKA phosphorylation which enhances Cl -secretion by apically located Cl -channels (CFTR) by increasing both single channel activity and plasma membrane insertion. Enhanced Cl -secretion results in lowered intracellular Cl -concentration and cell shrinkage, which are both stimuli for phosphorylation and activation of basolaterally located NKCC1 (Gimenez, 2006). Thus forskolin, which stimulates adenylate cyclase raising intracellular cAMP, generally leads indirectly to the phosphorylation of NKCC1 in secretory epithelia.…”

Section: Nkcc1 Phosphorylation In the Killifish Gill Is Regulated Viamentioning

confidence: 99%

Phosphorylation state of the Na+–K+–Cl− cotransporter (NKCC1) in the gills of Atlantic killifish (Fundulus heteroclitus) during acclimation to water of varying salinity

Flemmer

Monette

Djurišić

et al. 2010

Journal of Experimental Biology

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SUMMARYEuryhaline teleosts such as Atlantic killifish (Fundulus heteroclitus) are able to acclimate to changing environmental salinity by tightly regulating NaCl absorption and secretion across their gills. Many studies have examined the mechanisms responsible for long-term (days) salinity acclimation; however, much remains unknown about the mechanisms of acute (hours) salinity acclimation. In this study, we tested the hypotheses that phosphorylation of the Na + -K + -Cl -cotransporter (NKCC1) located in the basolateral membrane of the gill plays a role in acute salinity acclimation and that changes in NKCC1 phosphorylation are mediated by a cAMP-protein kinase A (cAMP-PKA) pathway. Using a phospho-specific antibody, we determined the time course of changes in total and phosphorylated NKCC1 protein during acclimation to water of various salinities. Long-term (≥14 days) acclimation of killifish to seawater (SW) and 2ϫ SW resulted in 4-to 6-fold and 5-to 8-fold increases, respectively, in total gill NKCC1 protein relative to fish maintained in freshwater (FW). NKCC1 was found to be between 20% and 70% activated in fish, with lower average activation in fish acclimated to SW and 2ϫ SW compared with FW fish. Increases and decreases in the fractional level of NKCC1 phosphorylation were seen within 1 h of transfer of fish to water of higher and lower salinity, respectively, consistent with a regulatory role of phosphorylation prior to an increase in the biosynthesis of NKCC1; large changes in protein expression of NKCC1 were observed over periods of hours to days. We found that NKCC1 phosphorylation is acutely regulated in the killifish gill in response to changing environmental salinity and that phosphorylation in excised gills increases in response to forskolin stimulation of the cAMP-PKA pathway. The role of phosphorylation is further underscored by the observation that mRNA expression of sterile 20 (Ste20)-related proline-alanine-rich kinase (SPAK) changes with salinity acclimation, being 2.7-fold greater in SW-acclimated killifish relative to FW fish. Overall, these results demonstrate an important role of NKCC1 phosphorylation in the gill of Atlantic killifish during acute salinity acclimation.

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“…NKCC1, the "housekeeping" isoform, exists in the brain and other systems, and its expression changes as it develops. NKCC2 seems to be exclusively expressed in the kidney and mainly related with the urine concentration by mediating apical Na + , K + and Cl -entry into renal epithelial cells [10] . The NKCC1 isoform is the larger one with 1 200 amino acid residues and a transcript size of 7.4 kb.…”

Section: Nkcc1mentioning

confidence: 99%

The role and the mechanism of γ-aminobutyric acid during central nervous system development

2008

Neurosci. Bull.

128

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γ-aminobutyric acid (GABA) is an inhibitory neurotransmitter in adult mammalian central nervous system (CNS). During CNS development, the role of GABA is switched from an excitatory transmitter to an inhibitory transmitter, which is caused by an inhibition of calcium influx into postsynaptic neuron derived from release of GABA. The switch is influenced by the neuronal chloride concentration. When the neuronal chloride concentration is at a high level, GABA acts as an excitatory neurotransmitter. When neuronal chloride concentration decreases to some degree, GABA acts as an inhibitory neurotransmitter. The neuronal chloride concentration is increased by Na + -K + -Cl --Cl -cotransporters 1 (NKCC1), and decreased by K + -Clcotransporter 2 (KCC2).

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Molecular mechanisms and regulation of furosemide-sensitive Na–K–Cl cotransporters

Cited by 71 publications

References 50 publications

Molecular components of signal amplification in olfactory sensory cilia

Molecular components of signal amplification in olfactory sensory cilia

Phosphorylation state of the Na+–K+–Cl− cotransporter (NKCC1) in the gills of Atlantic killifish (Fundulus heteroclitus) during acclimation to water of varying salinity

The role and the mechanism of γ-aminobutyric acid during central nervous system development

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