Formation of Functional Heterodimers between the TASK-1 and TASK-3 Two-pore Domain Potassium Channel Subunits

Czirják, Gábor; Enyedi, Péter

doi:10.1074/jbc.m107138200

Cited by 229 publications

(250 citation statements)

References 41 publications

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“…Most importantly, we demonstrated the TASK3 mutant not only was incapable of promoting tumor growth in nude mice, but also inhibited the tumor promotion function of the wild-type TASK3. We cannot at the present completely rule out the possibility that this dominant-negative mutant of TASK3 could interfere with the activity of other TASK channels through heterodimerization (34). A previous study showed the same TASK3 mutant did not have effect on TASK1 current when coexpressed in Xenopus oocytes (35), and we confirmed this observation in this study (data not shown).…”

Section: Discussionsupporting

confidence: 81%

Oncogenic potential of TASK3 (Kcnk9) depends on K⁺channel function

Pei¹,

Wiser²,

Slavin³

et al. 2003

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

159

124

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TASK3 gene (Kcnk9) is amplified and overexpressed in several types of human carcinomas. In this report, we demonstrate that a point mutation (G95E) within the consensus K ؉ filter of TASK3 not only abolished TASK3 potassium channel activity but also abrogated its oncogenic functions, including proliferation in low serum, resistance to apoptosis, and promotion of tumor growth. Furthermore, we provide evidence that TASK3 G95E is a dominant-negative mutation, because coexpression of the wild-type and the mutant TASK3 resulted in inhibition of K ؉ current of wild-type TASK3 and its tumorigenicity in nude mice. These results establish a direct link between the potassium channel activity of TASK3 and its oncogenic functions and imply that blockers for this potassium channel may have therapeutic potential for the treatment of cancers.T ASK (TWIK-related acid-sensitive K ϩ channels) channels are members of the two-pore domain family of potassium channels, whose structure consists of two-pore forming regions flanked by four transmembrane domains (1, 2). Like other two-pore domain members, these channels show little time or voltage dependence; thus, they have characteristics of leaky K ϩ channels, generating background currents that contribute to membrane potential and the regulation of cell excitability. The activity of TASK channels is modulated by volatile anesthetics (3, 4), neurotransmitters (5, 6), as well as extracellular pH in the physiological range (7-11). TASK3 is expressed at very low levels among the normal tissues except in the brain, where high levels expression of TASK3 were detected (7-9). The physiological functions of TASK channels are largely unknown, though their roles in the regulation of breathing (12, 13), aldosterone secretion (5) and anesthetic-mediated neuronal activity (14) have been proposed. Recently, we showed that TASK3 is amplified in 10% of breast cancers and is overexpressed at a higher frequency of breast, lung, colon, and metastatic prostate cancers (15), suggesting that TASK3 may play a role in pathogenesis of some human carcinomas.Is the dysregulated expression of TASK3 in tumor cells a consequence of their abnormal growth or is this K ϩ channel involved in promoting tumor growth? To begin to answer this question, we created an inactivating mutation of TASK3. We report here that TASK3 G95E is a dominant-negative mutation that abolishes not only TASK3 K ϩ channel activity but also its oncogenic functions. These results provide molecular basis for developing specific blockers for this K ϩ channel in the treatment of cancer. Materials and MethodsPlasmids and Mutagenesis. The coding region of TASK3 was cloned at BamHI and EcoRI sites of the pLPC retroviral expression vector (15) to generate pLPC-TASK3. Site-directed mutagenesis was performed to change Gly-95 to Glu to create pLPC-TASK3 G95E , by using QuickChange site-directed mutagenesis kit (Stratagene) according to the manufacturer's protocol. pTracer-TASK 3 G95E was generated by excising TASK3 G95E from pLPC vector and cloned at KpnI...

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Section: Discussionsupporting

confidence: 81%

Oncogenic potential of TASK3 (Kcnk9) depends on K⁺channel function

Pei¹,

Wiser²,

Slavin³

et al. 2003

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

159

124

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“…Thus, other unidentified mechanisms must exist for dimerization of K2P channels. This idea is further supported by a previous report showing TASK-1/TASK-3 heterodimer formation in the absence of cysteine residues normally present in the first loop of each channel 42,43 .…”

Section: Discussionsupporting

confidence: 76%

A disulphide-linked heterodimer of TWIK-1 and TREK-1 mediates passive conductance in astrocytes

et al. 2014

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TWIK-1 is a member of the two-pore domain K þ (K2P) channel family that plays an essential part in the regulation of resting membrane potential and cellular excitability. The physiological role of TWIK-1 has remained enigmatic because functional expression of TWIK-1 channels is elusive. Here we report that native TWIK-1 forms a functional channel at the plasma membrane of astrocytes. A search for TWIK-1-binding proteins led to the identification of TREK-1, another member of the K2P family. The TWIK-1/TREK-1 heterodimeric channel is formed via a disulphide bridge between residue C69 in TWIK-1 and C93 in TREK-1. Gene silencing demonstrates that surface expression of TWIK-1 and TREK-1 are interdependent. TWIK-1/TREK-1 heterodimers mediate astrocytic passive conductance and cannabinoidinduced glutamate release from astrocytes. Our study sheds new light on the diversity of K2P channels.

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“…The true dimeric assembly of KCNK9 with KCNK3 to form KCNK9‐KCNK3 heterodimers was confirmed by ruthenium red (RR) sensitivity analysis: KCNK9 was previously shown to be inhibited by RR (10 μmol/L), while KCNK9‐KCNK3 heterodimers and KCNK3 channels were not inhibited by RR 10 μmol/L as KCNK3‐containing channels lack a necessary glutamic acid residue (E70) for RR binding and channel pore block 11. Figure 6A (bottom) shows inhibition of KCNK9 currents by RR 10 μmol/L at pH 7.4, and Figure 6B (bottom) shows no effect by RR 10 μmol/L on KCNK9‐KCNK3 heterodimer currents.…”

Section: Resultsmentioning

confidence: 97%

“…KCNK9 is thought to be co‐expressed with KCNK3 in various tissues outside of the lung, including in the central nervous system, heart, and adrenal glands, and functional heterodimerization of KCNK3 with KCNK9 in multiple tissues has already been studied 6, 11, 12, 13, 175.…”

Section: Resultsmentioning

confidence: 99%

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The Impact of Heterozygous KCNK3 Mutations Associated With Pulmonary Arterial Hypertension on Channel Function and Pharmacological Recovery

Bohnen

Roman‐Campos

Terrenoire

et al. 2017

JAHA

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BackgroundHeterozygous loss of function mutations in the KCNK3 gene cause hereditary pulmonary arterial hypertension (PAH). KCNK3 encodes an acid‐sensitive potassium channel, which contributes to the resting potential of human pulmonary artery smooth muscle cells. KCNK3 is widely expressed in the body, and dimerizes with other KCNK3 subunits, or the closely related, acid‐sensitive KCNK9 channel.Methods and ResultsWe engineered homomeric and heterodimeric mutant and nonmutant KCNK3 channels associated with PAH. Using whole‐cell patch‐clamp electrophysiology in human pulmonary artery smooth muscle and COS7 cell lines, we determined that homomeric and heterodimeric mutant channels in heterozygous KCNK3 conditions lead to mutation‐specific severity of channel dysfunction. Both wildtype and mutant KCNK3 channels were activated by ONO‐RS‐082 (10 μmol/L), causing cell hyperpolarization. We observed robust gene expression of KCNK3 in healthy and familial PAH patient lungs, but no quantifiable expression of KCNK9, and demonstrated in functional studies that KCNK9 minimizes the impact of select KCNK3 mutations when the 2 channel subunits co‐assemble.ConclusionsHeterozygous KCNK3 mutations in PAH lead to variable loss of channel function via distinct mechanisms. Homomeric and heterodimeric mutant KCNK3 channels represent novel therapeutic substrates in PAH. Pharmacological and pH‐dependent activation of wildtype and mutant KCNK3 channels in pulmonary artery smooth muscle cells leads to membrane hyperpolarization. Co‐assembly of KCNK3 with KCNK9 subunits may provide protection against KCNK3 loss of function in tissues where both KCNK9 and KCNK3 are expressed, contributing to the lung‐specific phenotype observed clinically in patients with PAH because of KCNK3 mutations.

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Formation of Functional Heterodimers between the TASK-1 and TASK-3 Two-pore Domain Potassium Channel Subunits

Cited by 229 publications

References 41 publications

Oncogenic potential of TASK3 (Kcnk9) depends on K⁺channel function

Oncogenic potential of TASK3 (Kcnk9) depends on K⁺channel function

A disulphide-linked heterodimer of TWIK-1 and TREK-1 mediates passive conductance in astrocytes

The Impact of Heterozygous KCNK3 Mutations Associated With Pulmonary Arterial Hypertension on Channel Function and Pharmacological Recovery

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Formation of Functional Heterodimers between the TASK-1 and TASK-3 Two-pore Domain Potassium Channel Subunits

Cited by 229 publications

References 41 publications

Oncogenic potential of TASK3 (Kcnk9) depends on K+channel function

Oncogenic potential of TASK3 (Kcnk9) depends on K+channel function

A disulphide-linked heterodimer of TWIK-1 and TREK-1 mediates passive conductance in astrocytes

The Impact of Heterozygous KCNK3 Mutations Associated With Pulmonary Arterial Hypertension on Channel Function and Pharmacological Recovery

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Oncogenic potential of TASK3 (Kcnk9) depends on K⁺channel function

Oncogenic potential of TASK3 (Kcnk9) depends on K⁺channel function