Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties
BK K+ channels are critical regulators of neuron and muscle excitability, comprised of a tetramer of pore-forming αsubunits from the KCNMA1 gene and cell- and tissue-selective β subunits (KCNMB1-4). Mutations in KCNMA1 are associated with neurological disorders, including autism. However, little is...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2022-01-01
|
| Series: | Current Research in Physiology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2665944122000372 |
| _version_ | 1811295229057171456 |
|---|---|
| author | Hans J. Moldenhauer Ria L. Dinsdale Sara Alvarez Alberto Fernández-Jaén Andrea L. Meredith |
| author_facet | Hans J. Moldenhauer Ria L. Dinsdale Sara Alvarez Alberto Fernández-Jaén Andrea L. Meredith |
| author_sort | Hans J. Moldenhauer |
| collection | DOAJ |
| description | BK K+ channels are critical regulators of neuron and muscle excitability, comprised of a tetramer of pore-forming αsubunits from the KCNMA1 gene and cell- and tissue-selective β subunits (KCNMB1-4). Mutations in KCNMA1 are associated with neurological disorders, including autism. However, little is known about the role of neuronal BK channel β subunits in human neuropathology. The β2 subunit is expressed in central neurons and imparts inactivation to BK channels, as well as altering activation and deactivation gating. In this study, we report the functional effect of G124R, a novel KCNMB2 mutation obtained from whole-exome sequencing of a patient diagnosed with autism spectrum disorder. Residue G124, located in the extracellular loop between TM1 and TM2, is conserved across species, and the G124R missense mutation is predicted deleterious with computational tools. To investigate the pathogenicity potential, BK channels were co-expressed with β2WT and β2G124R subunits in HEK293T cells. BK/β2 currents were assessed from inside-out patches under physiological K+ conditions (140/6 mM K+ and 10 μM Ca2+) during activation and inactivation (voltage-dependence and kinetics). Using β2 subunits lacking inactivation (β2IR) revealed that currents from BK/β2IRG124R channels activated 2-fold faster and deactivated 2-fold slower compared with currents from BK/β2IRWT channels, with no change in the voltage-dependence of activation (V1/2). Despite the changes in the BK channel opening and closing, BK/β2G124R inactivation rates (τinact and τrecovery), and the V1/2 of inactivation, were unaltered compared with BK/β2WT channels under standard steady-state voltage protocols. Action potential-evoked current was also unchanged. Thus, the mutant phenotype suggests the β2G124R TM1-TM2 extracellular loop could regulate BK channel activation and deactivation kinetics. However, additional evidence is needed to validate pathogenicity for this patient-associated variant in KCNMB2. |
| first_indexed | 2024-04-13T05:30:17Z |
| format | Article |
| id | doaj.art-737c53f79ea148cf98936af77eadc7ce |
| institution | Directory Open Access Journal |
| issn | 2665-9441 |
| language | English |
| last_indexed | 2024-04-13T05:30:17Z |
| publishDate | 2022-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Current Research in Physiology |
| spelling | doaj.art-737c53f79ea148cf98936af77eadc7ce2022-12-22T03:00:28ZengElsevierCurrent Research in Physiology2665-94412022-01-015404413Effect of an autism-associated KCNMB2 variant, G124R, on BK channel propertiesHans J. Moldenhauer0Ria L. Dinsdale1Sara Alvarez2Alberto Fernández-Jaén3Andrea L. Meredith4Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD, USADept. of Physiology, University of Maryland School of Medicine, Baltimore, MD, USANimGenetics, Madrid, SpainDept. of Pediatric Neurology, Hospital Universitario Quirónsalud, School of Medicine, Universidad Europea de, Madrid, SpainDept. of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA; Corresponding author. Dept. of Physiology University of Maryland School of Medicine, 655 W. Baltimore St. Baltimore, MD, 21201, USA.BK K+ channels are critical regulators of neuron and muscle excitability, comprised of a tetramer of pore-forming αsubunits from the KCNMA1 gene and cell- and tissue-selective β subunits (KCNMB1-4). Mutations in KCNMA1 are associated with neurological disorders, including autism. However, little is known about the role of neuronal BK channel β subunits in human neuropathology. The β2 subunit is expressed in central neurons and imparts inactivation to BK channels, as well as altering activation and deactivation gating. In this study, we report the functional effect of G124R, a novel KCNMB2 mutation obtained from whole-exome sequencing of a patient diagnosed with autism spectrum disorder. Residue G124, located in the extracellular loop between TM1 and TM2, is conserved across species, and the G124R missense mutation is predicted deleterious with computational tools. To investigate the pathogenicity potential, BK channels were co-expressed with β2WT and β2G124R subunits in HEK293T cells. BK/β2 currents were assessed from inside-out patches under physiological K+ conditions (140/6 mM K+ and 10 μM Ca2+) during activation and inactivation (voltage-dependence and kinetics). Using β2 subunits lacking inactivation (β2IR) revealed that currents from BK/β2IRG124R channels activated 2-fold faster and deactivated 2-fold slower compared with currents from BK/β2IRWT channels, with no change in the voltage-dependence of activation (V1/2). Despite the changes in the BK channel opening and closing, BK/β2G124R inactivation rates (τinact and τrecovery), and the V1/2 of inactivation, were unaltered compared with BK/β2WT channels under standard steady-state voltage protocols. Action potential-evoked current was also unchanged. Thus, the mutant phenotype suggests the β2G124R TM1-TM2 extracellular loop could regulate BK channel activation and deactivation kinetics. However, additional evidence is needed to validate pathogenicity for this patient-associated variant in KCNMB2.http://www.sciencedirect.com/science/article/pii/S2665944122000372BK channelKCa1.1Calcium-activated potassium channelKCNMA1Potassium channelMaxiK |
| spellingShingle | Hans J. Moldenhauer Ria L. Dinsdale Sara Alvarez Alberto Fernández-Jaén Andrea L. Meredith Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties Current Research in Physiology BK channel KCa1.1 Calcium-activated potassium channel KCNMA1 Potassium channel MaxiK |
| title | Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties |
| title_full | Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties |
| title_fullStr | Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties |
| title_full_unstemmed | Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties |
| title_short | Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties |
| title_sort | effect of an autism associated kcnmb2 variant g124r on bk channel properties |
| topic | BK channel KCa1.1 Calcium-activated potassium channel KCNMA1 Potassium channel MaxiK |
| url | http://www.sciencedirect.com/science/article/pii/S2665944122000372 |
| work_keys_str_mv | AT hansjmoldenhauer effectofanautismassociatedkcnmb2variantg124ronbkchannelproperties AT rialdinsdale effectofanautismassociatedkcnmb2variantg124ronbkchannelproperties AT saraalvarez effectofanautismassociatedkcnmb2variantg124ronbkchannelproperties AT albertofernandezjaen effectofanautismassociatedkcnmb2variantg124ronbkchannelproperties AT andrealmeredith effectofanautismassociatedkcnmb2variantg124ronbkchannelproperties |