title: The inward rectifier potassium channel Kir2.1 is required for osteoblastogenesis.
abstract: Andersen's syndrome (AS) is a rare and dominantly inherited pathology, linked to the inwardly rectifying potassium channel Kir2.1. AS patients exhibit a triad of symptoms that include periodic paralysis, cardiac dysrhythmia and bone malformations. Some progress has been made in understanding the contribution of the Kir2.1 channel to skeletal and cardiac muscle dysfunctions, but its role in bone morphogenesis remains unclear. We isolated myoblast precursors from muscle biopsies of healthy individuals and typical AS patients with dysmorphic features. Myoblast cultures underwent osteogenic differentiation that led to extracellular matrix mineralization. Osteoblastogenesis was monitored through the activity of alkaline phosphatase, and through the hydroxyapatite formation using Alizarin Red and Von Kossa staining techniques. Patch-clamp recordings revealed the presence of an inwardly rectifying current in healthy cells that was absent in AS osteoblasts, showing the dominant-negative effect of the Kir2.1 mutant allele in osteoblasts. We also found that while control cells actively synthesize hydroxyapatite, AS osteoblasts are unable to efficiently form any extracellular matrix. To further demonstrate the role of the Kir2.1 channels during the osteogenesis, we inhibited Kir2.1 channel activity in healthy patient cells by applying extracellular Ba(2+) or using adenoviruses carrying mutant Kir2.1 channels. In both cases, cells were no longer able to produce extracellular matrixes. Moreover, osteogenic activity of AS osteoblasts was restored by rescue experiments, via wild-type Kir2.1 channel overexpression. These observations provide a proof that normal Kir2.1 channel function is essential during osteoblastogenesis.
authors.affiliation: University Nice Sophia Antipolis, Nice, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Sacco
authors.affiliation: University Nice Sophia Antipolis, Nice, France Laboratory of Excellence Ion Channel Science and Therapeutics, LP2M, UMR 7370 CNRS, Nice, France Faculté de Médecine, Nice, France.
authors.forename: Serena
authors.initials: S
authors.lastname: Giuliano
authors.affiliation: University Nice Sophia Antipolis, Nice, France Neuromuscular Disease Specialized Center, Nice University Hospital, Nice, France IRCAN, UMR 7248 CNRS, INSERM U1081, Nice, France and.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Sacconi
authors.affiliation: University Nice Sophia Antipolis, Nice, France Neuromuscular Disease Specialized Center, Nice University Hospital, Nice, France IRCAN, UMR 7248 CNRS, INSERM U1081, Nice, France and.
authors.forename: Claude
authors.initials: C
authors.lastname: Desnuelle
authors.affiliation: University Nice Sophia Antipolis, Nice, France Laboratory of Excellence Ion Channel Science and Therapeutics, LP2M, UMR 7370 CNRS, Nice, France Faculté de Médecine, Nice, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Barhanin
authors.affiliation: University Nice Sophia Antipolis, Nice, France Faculté de Médecine, Nice, France IBV, UMR 7277 CNRS, INSERM U1091, Nice, France.
authors.forename: Ez-zoubir
authors.initials: EZ
authors.lastname: Amri
authors.affiliation: University Nice Sophia Antipolis, Nice, France Laboratory of Excellence Ion Channel Science and Therapeutics, LP2M, UMR 7370 CNRS, Nice, France Faculté de Médecine, Nice, France said.bendahhou@unice.fr.
authors.forename: Saïd
authors.initials: S
authors.lastname: Bendahhou
mesh_terms: D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism; D006011:Glycogen Storage Disease Type IV / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism*
chemical_list: C489461:Kir2.1 channel; D024661:Potassium Channels, Inwardly Rectifying