The Journal of Neuroscience, November 22, 2006, 26(47):12127-12136; doi:10.1523/JNEUROSCI.3158-06.2006
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Cellular/Molecular
Regional Interaction of Endoplasmic Reticulum Ca2+ Signals between Soma and Dendrites through Rapid Luminal Ca2+ Diffusion
Yu Mi Choi,
Shin Hye Kim,
Sungkwon Chung,
Dae Yong Uhm, and
Myoung Kyu Park
Department of Physiology, Sungkyunkwan University School of Medicine and Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea
Correspondence should be addressed to Assoc. Prof. Myoung Kyu Park, Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon 440-746, Korea. Email: mkpark{at}med.skku.ac.kr
The endoplasmic reticulum (ER) Ca2+ store plays a key role in integration and conveyance of Ca2+ signals in highly polarized neurons. The interconnected ER network in neurons generates Ca2+ signals in local domains, but the regional interaction is unclear. Here, we show that continuous or repetitive applications of caffeine produced robust Ca2+ release from the ER Ca2+ store in dendritic areas without severe store depletion, but that similar stimuli applied to soma caused rapid store depletion in acutely isolated midbrain dopamine neurons. Partial emptying of the ER Ca2+ store within a dendrite caused a similar level of store depletion in unstimulated dendrites, as well as in soma. Photobleaching and local stimulation experiments revealed that Ca2+ and the dye trapped within the ER diffused rapidly from the soma to dendrites up to 90 µm, which we could resolve, suggesting that the ER network acts as a functional tunnel for rapid Ca2+ transport. These data imply that the ER in soma acts as a Ca2+ reservoir supplying Ca2+ to the dendritic store, and that the dendritic store, hence, is able to respond to Ca2+-mobilizing input signals endurably.
Key words: Ca2+ signal; endoplasmic reticulum; intracellular Ca2+ store; neuron; dopaminergic neuron; Ca2+ concentration in the endoplasmic reticulum; photobleaching
Received July 24, 2006;
revised Oct. 12, 2006;
accepted Oct. 14, 2006.
Correspondence should be addressed to Assoc. Prof. Myoung Kyu Park, Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon 440-746, Korea. Email: mkpark{at}med.skku.ac.kr
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