• Jiraporn Ousingsawat, Khaoula Talbi, Hilario Gómez-Martín, Anne Koy, Alberto Fernández-Jaén, Hasan Tekgül, Esra Serdaroğlu, Juan Darío Ortigoza-Escobar, Rainer Schreiber, and Karl Kunzelmann.
• Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany.
• Bmc Med. 2025 Jan 7; 23 (1): 1212.

BackgroundDystonia is a common neurological hyperkinetic movement disorder that can be caused by mutations in anoctamin 3 (ANO3, TMEM16C), a phospholipid scramblase and ion channel. We previously reported patients that were heterozygous for the ANO3 variants S651N, V561L, A599D and S651N, which cause dystonia by unknown mechanisms.MethodsWe applied electrophysiology, Ca2+ measurements and cell biological methods to analyze the molecular mechanisms that lead to aberrant intracellular Ca2+ signals and defective activation of K+ channels in patients heterozygous for the ANO3 variants.ResultsUpon expression, emptying of the endoplasmic reticulum Ca2+ store (store release) and particularly store-operated Ca2+ entry (SOCE) were strongly inhibited, leading to impaired activation of KCa3.1 (KCNN) K+ channels, but not of Na+-activated K+ channels (KNa; SLO2). The data provide evidence for a strongly impaired expression of store-operated ORAI1 Ca2+ influx channels in the plasma membrane of cells expressing ANO3 variants.ConclusionsDysregulated Ca2+ signaling by ANO3 variants may impair the activation of K+ channels in striatal neurons of the brain, thereby causing dystonia. Furthermore, the data provide a first indication of a possible regulation of protein expression in the plasma membrane by ANO3, as has been described for other anoctamins.© 2025. The Author(s).

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