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Phosphorylation-dependent binding of 14-3-3 proteins controls TRESK regulation.

ABSTRACT: The two-pore domain K(+) channel, TRESK (TWIK-related spinal cord K(+) channel) is reversibly activated by the calcium/calmodulin-dependent protein phosphatase, calcineurin. In the present study, we report that 14-3-3 proteins directly bind to the intracellular loop of TRESK and control the kinetics of the calcium-dependent regulation of the channel. Coexpression of 14-3-3eta with TRESK blocked, whereas the coexpression of a dominant negative form of 14-3-3eta accelerated the return of the K(+) current to the resting state after the activation mediated by calcineurin in Xenopus oocytes. The direct action of 14-3-3 was spatially restricted to TRESK, since 14-3-3eta was also effective, when it was tethered to the channel by a flexible polyglutamine-containing chain. The effect of both the coexpressed and chained 14-3-3 was alleviated by the microinjection of Ser(P)-Raf259 phosphopeptide that competes with TRESK for binding to 14-3-3. The gamma and eta isoforms of 14-3-3 controlled TRESK regulation, whereas the beta, zeta, epsilon, sigma, and tau isoforms failed to influence the mechanism significantly. Phosphorylation of serine 264 in mouse TRESK was required for the binding of 14-3-3eta. Because 14-3-3 proteins are ubiquitous, they are expected to control the duration of calcineurin-mediated TRESK activation in all the cell types that express the channel, depending on the phosphorylation state of serine 264. This kind of direct control of channel regulation by 14-3-3 is unique within the two-pore domain K(+) channel family.

SUBMITTER: Czirjak G

PROVIDER: S-EPMC3259650 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

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Phosphorylation-dependent binding of 14-3-3 proteins controls TRESK regulation.

Czirják Gábor G Vuity Drazsen D Enyedi Péter P

The Journal of biological chemistry 20080408 23

The two-pore domain K(+) channel, TRESK (TWIK-related spinal cord K(+) channel) is reversibly activated by the calcium/calmodulin-dependent protein phosphatase, calcineurin. In the present study, we report that 14-3-3 proteins directly bind to the intracellular loop of TRESK and control the kinetics of the calcium-dependent regulation of the channel. Coexpression of 14-3-3eta with TRESK blocked, whereas the coexpression of a dominant negative form of 14-3-3eta accelerated the return of the K(+) ...[more]

PMID: 18397886

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Project description:ObjectiveMetabolic stress primes monocytes for accelerated chemokine-mediated adhesion, migration, and recruitment into vascular lesions by increasing actin remodeling. The mechanism linking metabolic stress to accelerated actin turnover and enhanced monocyte migration was not known. We tested the hypothesis that in metabolically primed monocytes, the acceleration of monocyte chemoattractant protein-1-induced chemotaxis is mediated by the hyperactivation of cofilin.Approach and resultsMetabolic priming was induced by exposing human THP-1 monocytes to diabetic conditions, that is, human native low-density lipoprotein plus high glucose concentrations. In healthy monocytes, monocyte chemoattractant protein-1 induced the phosphorylation and inactivation of cofilin. This response was completely blocked in metabolically primed monocytes but restored by overexpression of the thiol transferase, glutaredoxin 1. Cofilin kinase, LIM kinase 1, and cofilin phosphatase, Slingshot-1L, were not affected by metabolic stress. However, metabolic priming increased 3.8-fold the S-glutathionylation of the Slingshot-1L-binding protein 14-3-3ζ (zeta), resulting in its caspase-dependent degradation. Glutaredoxin 1 overexpression inhibited low-density lipoprotein plus high glucose-induced S-glutathionylation and degradation of 14-3-3ζ. The C25S mutant of 14-3-3ζ was resistant to both S-glutathionylation and degradation induced by low-density lipoprotein plus high glucose. Overexpression of the C25S mutant restored monocyte chemoattractant protein-1-induced cofilin phosphorylation and prevented accelerated migration of metabolically stressed monocytes, suggesting that loss of 14-3-3ζ increases the pool of free Slingshot-1L phosphatase, thereby preventing the phosphorylation and deactivation of cofilin in response to chemokine activation.ConclusionsBy preventing the inactivation of cofilin, metabolic stress-induced degradation of 14-3-3ζ promotes the conversion of blood monocytes into a hypermigratory, proatherogenic phenotype.

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Phosphorylation-dependent binding of 14-3-3 proteins controls TRESK regulation.

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Phosphorylation-dependent binding of 14-3-3 proteins controls TRESK regulation.

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