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| TR |
TITLE |
AUTHORS |
KEYWORDS |
MATERIALS & METHODS
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MICROSCOPIC
TECHNIQUES |
SPECIES |
MORPHOLOGY |
CELL
LINE |
| 611 |
Ca2+
shuttling between endoplasmic reticulum and
mitochondria underlying Ca2ž oscillations |
Kiyoaki
Ishii, Kenzo Hirose & Masamitsu Iino |
calcium
oscillation; endoplasmic reticulum; GFP;
imaging; mitochondria |
HeLa cells transduced with retroviruses
encoding the indicators and cultured in glass-bottomed dish
(MatTek) were loaded at room temperature (23 1C–25 1C) with 5 mM indo-5F AM or fura-2 AM in
physiological salt solution…
|
Inverted
Fluorescence Microscopy |
|
|
HeLa |
| Abstract |
| |
Although many cell functions are regulated by Ca2þ
oscillations induced by a cyclic release of Ca2þ from intracellular Ca2þ stores,
the pacemaker mechanism of Ca2þ oscillations remains to be explained. Using green fluorescent
protein-based Ca2þ indicators that are targeted to intracellular Ca2þ stores, the
endoplasmic reticulum (ER) and mitochondria, we found that Ca2þ shuttles between the ER
and mitochondria in phase with Ca2þ oscillations. Following agonist stimulation, Ca2þ
release from the ER generated the first Ca2þ oscillation and loaded mitochondria with
Ca2þ. Before the second Ca2þ oscillation, Ca2þ release from the mitochondria
by means of the Naþ/Ca2þ exchanger caused a gradual increase in cytoplasmic Ca2þ
concentration, inducing a regenerative ER Ca2þ release, which generated the peak of Ca2þ
oscillation and partially reloaded the mitochondria. This sequence of events was repeated until
mitochondrial Ca2þ was depleted. Thus, Ca2þ shuttling between the ER and mitochondria
may have a pacemaker role in the generation of Ca2þ oscillations. |
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