Ryanodine receptor 1 mediates Ca2+ transport and influences the biomechanical properties in RBCs

Ryanodine receptors (RyRs) are a family of Ca2+ channel proteins that mediate the massive release of Ca2+ from the endoplasmic reticulum into the cytoplasma. In the present study, we manipulated the incorporation of RyR1 into RBC membrane and investigated its influences on the intracellular Ca2+ ([Ca2+]in) level and the biomechanical properties in RBCs. The incorporation of RyR1 into RBC membranes was demonstrated by both immunofluorescent staining and the change of [Ca2+]in of RBCs. In the presence of RyR1, [Ca2+]in showed biphasic changes, i.e., it increased with the extracellular Ca2+ ([Ca2+]ex) up to 5 μM and then decreased with the further increase of [Ca2+]ex. However, [Ca2+]in remained constant in the absence of the RyR1. The results of biomechanical measurements on RBCs, including deformability, osmotic fragility, and membrane microviscosity, reflected similar biphasic changes of [Ca2+]in mediated by RyR1 with the increases of [Ca2+]ex. Therefore, it is believed that RyR1 can incorporate into RBC membrane in vitro, and mediate Ca2+ influx, and then regulate RBC biomechanical properties. This information suggests that RBCs may serve as a model to study the function of RyR1 as a Ca2+ release channel.