Molecular structure and function of big calcium-activated potassium channels in skeletal muscle: pharmacological perspectives

• Published in: Physiological genomics Vol. 49; no. 6; pp. 306 - 317
• Main Authors: Maqoud, Fatima, Cetrone, Michela, Mele, Antonietta, Tricarico, Domenico
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.06.2017
• Subjects: Alternative splicing; Alternative Splicing - genetics; Alternative Splicing - physiology; Animals; Calcium (intracellular); Calcium channels; Calcium conductance; Channel gating; Cyclic AMP-Dependent Protein Kinases - genetics; Cyclic AMP-Dependent Protein Kinases - metabolism; Cytoplasm - genetics; Cytoplasm - metabolism; Drug delivery; Drug development; HEK293 Cells; Humans; Hyperkalemia; Hypokalemia; Intracellular; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits - genetics; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits - metabolism; Large-Conductance Calcium-Activated Potassium Channels - genetics; Large-Conductance Calcium-Activated Potassium Channels - metabolism; Mammalian cells; MCF-7 Cells; Metabolites; Mice; Models, Biological; Molecular Structure; Muscle, Skeletal - metabolism; Musculoskeletal system; Paralysis; Potassium; Potassium channels; Potassium channels (calcium-gated); Potassium conductance; Protein interaction; Skeletal muscle; Structure-function relationships; splicing mechanism; sarcolemma BK channel; potassium channel openers; neuromuscular disorders
• DOI: 10.1152/physiolgenomics.00121.2016
• ISSN: 1094-8341; 1531-2267

The large-conductance Ca 2+ -activated K + (BK) channel is broadly expressed in various mammalian cells and tissues such as neurons, skeletal muscles (sarco-BK), and smooth muscles. These channels are activated by changes in membrane electrical potential and by increases in the concentration of intracellular calcium ion (Ca 2+ ). The BK channel is subjected to many mechanisms that add diversity to the BK channel α-subunit gene. These channels are indeed subject to alternative splicing, auxiliary subunits modulation, posttranslational modifications, and protein-protein interactions. BK channels can be modulated by diverse molecules that may induce either an increase or decrease in channel activity. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, have been found to be relevant in many physiological processes. BK channel diversity is obtained by means of alternative splicing and modulatory β- and γ-subunits. The association of the α-subunit with β- or with γ-subunits can change the BK channel phenotype, functional diversity, and pharmacological properties in different tissues. In the case of the skeletal muscle BK channel (sarco-BK channel), we established that the main mechanism regulating BK channel diversity is the alternative splicing of the KCNMA1/slo1 gene encoding for the α-subunit generating different splicing isoform in the muscle phenotypes. This finding helps to design molecules selectively targeting the skeletal muscle subtypes. The use of drugs selectively targeting the skeletal muscle BK channels is a promising strategy in the treatment of familial disorders affecting muscular skeletal apparatus including hyperkalemia and hypokalemia periodic paralysis.