Premium
STIM1 INTERACTS WITH THE VOLTAGE SENSOR (L‐CHANNEL) OF L6 SKELETAL MUSCLE CELL CULTURES
Author(s) -
Pitake Saumitra,
Ochs Raymond S
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.772.1
Subject(s) - orai1 , stim1 , endoplasmic reticulum , chemistry , voltage dependent calcium channel , microbiology and biotechnology , trpc1 , depolarization , myogenesis , ryanodine receptor , calcium , t type calcium channel , calcium channel , biophysics , myocyte , biology , ion channel , biochemistry , receptor , organic chemistry
Store‐operated calcium entry (SOCE) is the process of external Ca 2+ entry driven by depletion of intracellular (endoplasmic reticumum (ER)) Ca 2+ . Entry of Ca 2+ is known to occur through the Orai1 channel, and the concentration of ER Ca 2+ is sensed by the STIM1 protein. In L6 muscle cells, Ca 2+ entry also occurs during stimulation (exciation contraction calcium entry, ECCE). This Ca 2+ flow is known to occur through the L‐channel and is inhibited by diltiazem and dihydropyridines. Surprisingly, we found that these inhibitors also blocked SOCE. To further examine this, we conducted co‐immunoprecipitation studies to study the interaction of STIMI, Orail and the L‐channel. We found the L‐channel had significant association with Stiml when calcium was depleted. This interaction was prevented by the STIMI blocker, ML‐9, or by K‐depolarization. In addition, ECCE Ca 2+ currents were attenuated in STIM1 knockdown myotubes, but not Orai1 knockdowns. Similarly, the STIM1 inhibitor ML‐9 inhibited ECCE Ca 2+ currents, while the Orai1 inhibitor BTP‐2 had no effect. Both of these inhibitors blocked SOCE Ca 2+ currents. We conclude that the L‐channel interacts with the STIM1 protein during SOCE, which was unexpected since the L‐channel is known to play a role only in excitation‐contraction calcium release and not the refilling of ER stores.