Mechanistic ion channel interactions in red cells of patients with Gardos channelopathy

In patients with Gardos channelopathy (p.R352H), an increased concentration of intracellular Ca2+ was previously reported. This is a surprising finding because the Gardos channel (K(Ca)3.1) is a K+ channel. Here, we confirm the increased intracellular Ca2+ for patients with the K(Ca)3.1 mutation p.S314P. Furthermore, we provide the concept of K(Ca)3.1 activity resulting in a flickering of red blood cell (RBC) membranepotential, which activates the Ca(v)2.1 channel allowing Ca2+ to enter the RBC. Activity of the nonselective cation channel Piezo1 modulates the aforementioned interplay in away that a closed Piezo1 is in favor of the K(Ca)3.1-Ca(v)2.1 interaction. In contrast, Piezol openings compromise the membrane potential flickering, thus limiting the activity of Ca(v)2.1. With the compound NS309, we mimic a gain-of-function mutation of K(Ca)3.1. Assessing the RBC Ca2+ response by Fluo-4-based flow cytometry and by measuring the membrane potential using the Macey-Bennekou-Egee method, we provide data that support the concept of the K(Ca)3.1/Ca(v)2.1/Piezo1 interplay as a partial explanation for an increased number of high Ca2+ RBCs. With the pharmacological inhibition of K(Ca)3.1 (TRAM34 and Senicapoc), Ca(v)2.1 (omega-agatoxin TK), and Piezo1 (GsMTx-4), we could project the NS309 behavior of healthy RBCs to the RBCs of Gardos channelopathy patients.

Automated summary

In patients with Gardos channelopathy, there is an increased intracellular Ca2+ concentration. The activity of K(Ca)3.1 may lead to membrane potential flickering in red blood cells, activating the Ca(v)2.1 channel and allowing Ca2+ entry.