| First Author | Zhang H | Year | 2015 |
| Journal | Proc Natl Acad Sci U S A | Volume | 112 |
| Issue | 41 | Pages | E5618-27 |
| PubMed ID | 26424448 | Mgi Jnum | J:225570 |
| Mgi Id | MGI:5693663 | Doi | 10.1073/pnas.1503847112 |
| Citation | Zhang H, et al. (2015) STIM1-Ca2+ signaling modulates automaticity of the mouse sinoatrial node. Proc Natl Acad Sci U S A 112(41):E5618-27 |
| abstractText | 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. |
