Disruption of actin filaments induces mitochondrial Ca²⁺release to the cytoplasm and [Ca²⁺]_cchanges in <it>Arabidopsis </it>root hairs

• Main Authors: Baluška František, Liu Peng, Zhang Haiyan, Ling Yu, Zhu Yingfang, Wang Yuqing, Šamaj Jozef, Lin Jinxing, Wang Qinli
• Format: Article
• Language: English
• Published: BMC 2010-03-01
• Series: BMC Plant Biology
• Online Access: http://www.biomedcentral.com/1471-2229/10/53

<p>Abstract</p> <p>Background</p> <p>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 <it>Arabidopsis </it>root hairs.</p> <p>Results</p> <p>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 <it>Arabidopsis </it>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.</p> <p>Conclusions</p> <p>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.</p>