Protein Kinase C (PKC)-promoted Endocytosis of Glutamate Transporter GLT-1 Requires Ubiquitin Ligase Nedd4-2-dependent Ubiquitination but Not Phosphorylation

García-Tardón, Noemí; González‐González, Inmaculada M.; Villarreal, Jaime Martínez de; Fernández-Sánchez, Enrique; Giménez, Cecilio; Zafra, Francisco

doi:10.1074/jbc.m112.355909

Cited by 81 publications

(102 citation statements)

References 47 publications

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“…Nedd4-2 promotes the ubiquitination of many channels and transporters, and leads these membrane proteins to internalize from the cell surface and subsequently to be degraded [15, 17, 27]. As a result, the expression of these membrane proteins at the cell surface is reduced, and their function is decreased.…”

Section: Resultsmentioning

confidence: 99%

“…Nedd4-2 has been reported to interact either directly or indirectly with its target proteins [15, 17, 28, 29], and thus, we assessed whether there is an association between Nedd4-2 and hOAT4 through co-immunoprecipitation assay. As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Among these mediators is the ubiquitin ligase Nedd4-2, which has been shown to play a key role in the regulation of many membrane proteins such as epithelial sodium channel ENaC, potassium channel hERG, and the human excitatory amino acid transporter EAAT2 [17, 27, 39]. Nedd4-2 catalyzes the conjugation of ubiquitin molecules to its target membrane proteins, which leads to the internalization of these membrane proteins from cell surface and subsequent degradation.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, a substrate can be modified by different types of ubiquitin conjugation: monoubiquitination (conjugation of one single ubiquitin to one single lysine on the substrate), or polyubiquitination (extended polyubiquitin chain). More and more evidence indicates that ubiquitination serves as a major signal in PKC-regulated cellular trafficking of transporters, including dopamine transporter (DAT) [15], cationic amino acid transporter (CAT-1) [16], and glutamate transporter (GLT-1) [17]. …”

Section: Introductionmentioning

confidence: 99%

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Serum- and glucocorticoid-inducible kinase SGK2 regulates human organic anion transporters 4 via ubiquitin ligase Nedd4-2

Wang

Toh

et al. 2016

Biochemical Pharmacology

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Human organic anion transporter 4 (hOAT4) belongs to a family of organic anion transporters that play critical roles in the body disposition of clinically important drugs, including anti-viral therapeutics, anti-cancer drugs, antibiotics, antihypertensives, and anti-inflammatories. hOAT4 is abundantly expressed in the kidney and placenta. In the current study, we examined the regulation of hOAT4 by serum- and glucocorticoid-inducible kinase 2 (sgk2) in the kidney COS-7 cells. We showed that sgk2 stimulated hOAT4 transport activity. Such stimulation mainly resulted from an increased cell surface expression of the transporter, kinetically revealed as an increased maximal transport velocity Vmax without significant change in substrate-binding affinity Km. We further showed that regulation of hOAT4 activity by sgk2 was mediated by ubiquitin ligase Nedd4-2. Overexpression of Nedd4-2 enhanced hOAT4 ubiquitination, and inhibited hOAT4 transport activity, whereas overexpression of ubiquitin ligase-dead mutant Nedd4-2/C821A or siRNA knockdown of endogenous Nedd4-2 had opposite effects on hOAT4. Our co-immunoprecipitation experiment revealed that sgk2 weakened the association between hOAT4 and Nedd4-2. In conclusion, our study demonstrated for the first time that sgk2 stimulated hOAT4 transport activity by abrogating the inhibition effect of Nedd4-2 on the transporter.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Serum- and glucocorticoid-inducible kinase SGK2 regulates human organic anion transporters 4 via ubiquitin ligase Nedd4-2

Wang

Toh

et al. 2016

Biochemical Pharmacology

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“…Nevertheless, it is not clear whether these changes in the phosphorylation status are the cause of the observed alterations in the trafficking of the transporters. Recent evidence obtained for GLT-1 revealed that PKC promotes the phosphorylation of GLT-1, but this process is independent of the internalization of the transporter that is dependent on ubiquitination (García-Tardón et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Differential regulation of the glutamate transporters GLT-1 and GLAST by GSK3β

Jiménez¹,

Núñez²,

Ibáñez³

et al. 2014

Neurochemistry International

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Interleukin‐1 beta enhances endocytosis of glial glutamate transporters in the spinal dorsal horn through activating protein kinase C

Yan

Yadav

Gao

et al. 2014

Glia

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Excessive activation of glutamate receptors in spinal dorsal horn neurons is a key mechanism leading to abnormal neuronal activation in pathological pain conditions. Previous studies have shown that activation of glutamate receptors in the spinal dorsal horn is enhanced by impaired glial glutamate transporter functions and pro-inflammatory cytokines including interleukin-1 beta (IL-1β). In this study, we for the first time revealed that spinal glial glutamate transporter activities in the neuropathic animals are attenuated by endogenous IL-1β. Specifically, we demonstrated that nerve injury results in an increased expression of IL-1β and activation of PKC in the spinal dorsal horn as well as suppression of glial glutamate uptake activities. We provided evidence that the nerve-injury induced suppression of glial glutamate uptake is at least in part ascribed to endogenous IL-1β and activation of PKC in the spinal dorsal horn. IL-1β reduces glial glutamate transporter activities through enhancing the endocytosis of both GLT-1 and GLAST glial glutamate transporters. The IL-1β induced trafficking of glial glutamate transporters is through the calcium/PKC signaling pathway, and the dynamin-dependent endocytosis, which is dependent on the integrity of actin filaments. The signaling pathway regulating glial glutamate transporters revealed in this study provides novel targets to attenuate aberrant activation of glutamate receptors in the spinal dorsal horn, which could ultimately help the development of analgesics.

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Protein Kinase C (PKC)-promoted Endocytosis of Glutamate Transporter GLT-1 Requires Ubiquitin Ligase Nedd4-2-dependent Ubiquitination but Not Phosphorylation

Cited by 81 publications

References 47 publications

Serum- and glucocorticoid-inducible kinase SGK2 regulates human organic anion transporters 4 via ubiquitin ligase Nedd4-2

Serum- and glucocorticoid-inducible kinase SGK2 regulates human organic anion transporters 4 via ubiquitin ligase Nedd4-2

Differential regulation of the glutamate transporters GLT-1 and GLAST by GSK3β

Interleukin‐1 beta enhances endocytosis of glial glutamate transporters in the spinal dorsal horn through activating protein kinase C

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