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Mitochondria's Role in Store‐Operated Calcium Entry
Author(s) -
Barry Christina Jean,
Cioffi Donna L.,
Stevens Troy
Publication year - 2008
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.22.1_supplement.964.25
Subject(s) - calcium , cytosol , extracellular , chemistry , calcium atpase , thapsigargin , calcium pump , t type calcium channel , voltage dependent calcium channel , calcium in biology , calcium signaling , microbiology and biotechnology , mitochondrion , antimycin a , biochemistry , biology , atpase , organic chemistry , enzyme
Inflammatory agonists deplete calcium from the endoplasmic reticulum and activate calcium entry in a process referred to as store‐operated calcium (SOC). Calcium store depletion can be distinctly measured from calcium entry using a recalcification protocol, in which store depletion is activated in the presence of low extracellular calcium. Upon addition of high extracellular calcium, calcium enters through activated SOC channels. We loaded pulmonary artery endothelial cells with either a membrane‐localized calcium indicator (FFP‐18) or a cytosolic‐calcium indicator (Fura‐2). In the presence of 100 nM calcium, thapsigargin‐induced store depletion transiently increased both membrane and cytosolic calcium and returned to baseline. Upon addition of 5 mM extracellular calcium, SOC entry stably increased membrane calcium whereas cytosolic calcium transiently increased then slowly decreased. We sought to determine whether the decrease in cytosolic calcium was due to calcium uptake by mitochondria. Mitochondrial calcium uptake was inhibited using CCCP or antimycin and oligomycin. Inhibition of mitochondrial calcium uptake increased cytosolic calcium, but did not prevent the decline in cytosolic calcium observed following SOC entry. Thus, mitochondria sequester cytosolic calcium, but are not solely responsible for the decrease in cytosolic calcium measured during SOC entry. Supported by HL60024.