STIM1-Ca2+ signaling modulates automaticity of the mouse sinoatrial node.

TitleSTIM1-Ca2+ signaling modulates automaticity of the mouse sinoatrial node.
Publication TypeConference Paper
Year of Publication2015
AuthorsZhang, H, Sun, AY, Kim, JJ, Graham, V, Finch, EA, Nepliouev, I, Zhao, G, Li, T, Lederer, WJ, Stiber, JA, Pitt, GS, Bursac, N, and Rosenberg, PB
Conference NameProceedings of the National Academy of Sciences of USA
Date Published10/2015

Cardiac pacemaking is governed by specialized cardiomyocytes located in the sinoatrial node (SAN). SAN cells (SANCs) integrate voltage-gated currents from channels on the membrane surface (membrane clock) with rhythmic Ca(2+) release from internal Ca(2+) stores (Ca(2+) clock) to adjust heart rate to meet hemodynamic demand. Here, we report that stromal interaction molecule 1 (STIM1) and Orai1 channels, key components of store-operated Ca(2+) entry, are selectively expressed in SANCs. Cardiac-specific deletion of STIM1 in mice resulted in depletion of sarcoplasmic reticulum (SR) Ca(2+) stores of SANCs and led to SAN dysfunction, as was evident by a reduction in heart rate, sinus arrest, and an exaggerated autonomic response to cholinergic signaling. Moreover, STIM1 influenced SAN function by regulating ionic fluxes in SANCs, including activation of a store-operated Ca(2+) current, a reduction in L-type Ca(2+) current, and enhancing the activities of Na(+)/Ca(2+) exchanger. In conclusion, these studies reveal that STIM1 is a multifunctional regulator of Ca(2+) dynamics in SANCs that links SR Ca(2+) store content with electrical events occurring in the plasma membrane, thereby contributing to automaticity of the SAN.