BMC Plant Biology (Mar 2010)

Disruption of actin filaments induces mitochondrial Ca<sup>2+ </sup>release to the cytoplasm and [Ca<sup>2+</sup>]<sub>c </sub>changes in <it>Arabidopsis </it>root hairs

  • Baluška František,
  • Liu Peng,
  • Zhang Haiyan,
  • Ling Yu,
  • Zhu Yingfang,
  • Wang Yuqing,
  • Šamaj Jozef,
  • Lin Jinxing,
  • Wang Qinli

DOI
https://doi.org/10.1186/1471-2229-10-53
Journal volume & issue
Vol. 10, no. 1
p. 53

Abstract

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Abstract Background Mitochondria are dynamic organelles that move along actin filaments, and serve as calcium stores in plant cells. The positioning and dynamics of mitochondria depend on membrane-cytoskeleton interactions, but it is not clear whether microfilament cytoskeleton has a direct effect on mitochondrial function and Ca2+ storage. Therefore, we designed a series of experiments to clarify the effects of actin filaments on mitochondrial Ca2+ storage, cytoplasmic Ca2+ concentration ([Ca2+]c), and the interaction between mitochondrial Ca2+ and cytoplasmic Ca2+ in Arabidopsis root hairs. Results In this study, we found that treatments with latrunculin B (Lat-B) and jasplakinolide (Jas), which depolymerize and polymerize actin filaments respectively, decreased membrane potential and Ca2+ stores in the mitochondria of Arabidopsis root hairs. Simultaneously, these treatments induced an instantaneous increase of cytoplasmic Ca2+, followed by a continuous decrease. All of these effects were inhibited by pretreatment with cyclosporin A (Cs A), a representative blocker of the mitochondrial permeability transition pore (mPTP). Moreover, we found there was a Ca2+ concentration gradient in mitochondria from the tip to the base of the root hair, and this gradient could be disrupted by actin-acting drugs. Conclusions Based on these results, we concluded that the disruption of actin filaments caused by Lat-B or Jas promoted irreversible opening of the mPTP, resulting in mitochondrial Ca2+ release into the cytoplasm, and consequent changes in [Ca2+]c. We suggest that normal polymerization and depolymerization of actin filaments are essential for mitochondrial Ca2+ storage in root hairs.