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Impheng H, Lemmers C, Bouasse M, Legros C, Pakaprot N, Guérineau NC, Lory P, Monteil A. The sodium leak channel NALCN regulates cell excitability of pituitary endocrine cells. FASEB J 2021; 35:e21400. [PMID: 33793981 DOI: 10.1096/fj.202000841rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 11/11/2022]
Abstract
Anterior pituitary endocrine cells that release hormones such as growth hormone and prolactin are excitable and fire action potentials. In these cells, several studies previously showed that extracellular sodium (Na+ ) removal resulted in a negative shift of the resting membrane potential (RMP) and a subsequent inhibition of the spontaneous firing of action potentials, suggesting the contribution of a Na+ background conductance. Here, we show that the Na+ leak channel NALCN conducts a Ca2+ - Gd3+ -sensitive and TTX-resistant Na+ background conductance in the GH3 cell line, a cell model of pituitary endocrine cells. NALCN knockdown hyperpolarized the RMP, altered GH3 cell electrical properties and inhibited prolactin secretion. Conversely, the overexpression of NALCN depolarized the RMP, also reshaping the electrical properties of GH3 cells. Overall, our results indicate that NALCN is functional in GH3 cells and involved in endocrine cell excitability as well as in hormone secretion. Indeed, the GH3 cell line suitably models native pituitary cells that display a similar Na+ background conductance and appears as a proper cellular model to study the role of NALCN in cellular excitability.
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Affiliation(s)
- Hathaichanok Impheng
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Céline Lemmers
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France.,PVM, BCM, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Malik Bouasse
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Christian Legros
- MITOVASC Institute, UMR CNRS 6015 - UMR INSERM U1083, Université d'Angers, Angers, France
| | - Narawut Pakaprot
- Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nathalie C Guérineau
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Philippe Lory
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Arnaud Monteil
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France.,PVM, BCM, Université de Montpellier, CNRS, INSERM, Montpellier, France
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Bouasse M, Impheng H, Servant Z, Lory P, Monteil A. Functional expression of CLIFAHDD and IHPRF pathogenic variants of the NALCN channel in neuronal cells reveals both gain- and loss-of-function properties. Sci Rep 2019; 9:11791. [PMID: 31409833 PMCID: PMC6692409 DOI: 10.1038/s41598-019-48071-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 07/29/2019] [Indexed: 12/24/2022] Open
Abstract
The excitability of neurons is tightly dependent on their ion channel repertoire. Among these channels, the leak sodium channel NALCN plays a crucial role in the maintenance of the resting membrane potential. Importantly, NALCN mutations lead to complex neurodevelopmental syndromes, including infantile hypotonia with psychomotor retardation and characteristic facies (IHPRF) and congenital contractures of limbs and face, hypotonia and developmental delay (CLIFAHDD), which are recessively and dominantly inherited, respectively. Unfortunately, the biophysical properties of NALCN are still largely unknown to date, as well as the functional consequences of both IHPRF and CLIFAHDD mutations on NALCN current. Here we have set-up the heterologous expression of NALCN in the neuronal cell line NG108-15 to investigate the electrophysiological properties of NALCN carrying representative IHPRF and CLIFAHDD mutations. Several original properties of the wild-type (wt) NALCN current were retrieved: mainly carried by external Na+, blocked by Gd3+, insensitive to TTX and potentiated by low external Ca2+ concentration. However, we found that this current displays a time-dependent inactivation in the −80/−40 mV range of membrane potential, and a non linear current-voltage relationship indicative of voltage sensitivity. Importantly, no detectable current was recorded with the IHPRF missense mutation p.Trp1287Leu (W1287L), while the CLIFAHDD mutants, p.Leu509Ser (L509S) and p.Tyr578Ser (Y578S), showed higher current densities and slower inactivation, compared to wt NALCN current. This study reveals that heterologous expression of NALCN channel can be achieved in the neuronal cell line NG108-15 to study the electrophysiological properties of wt and mutants. From our results, we conclude that IHPRF and CLIFAHDD missense mutations are loss- and gain-of-function variants, respectively.
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Affiliation(s)
- Malik Bouasse
- IGF, CNRS, INSERM, University of Montpellier, LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Hathaichanok Impheng
- IGF, CNRS, INSERM, University of Montpellier, LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Zoe Servant
- IGF, CNRS, INSERM, University of Montpellier, LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Philippe Lory
- IGF, CNRS, INSERM, University of Montpellier, LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Arnaud Monteil
- IGF, CNRS, INSERM, University of Montpellier, LabEx 'Ion Channel Science and Therapeutics', Montpellier, France.
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