Microinjected F-actin into dividing newt eggs moves toward the next cleavage furrow together with Ca2+ stores with inositol 1,4,5-trisphosphate receptor in a microtubule- and microtubule motor-dependent manner

Ital J Anat Embryol. 2008 Jul-Sep;113(3):143-51.

Abstract

It has been reported that F-actin is transported to the presumptive cleavage furrow along the cortex during anaphase-cytokinesis, an event termed cortical actin flow in animal cultured cells. The motor source has remained unknown. We reported that Ca2+ stores with IP3 receptor (IP3R) was re-distributed from the polar cortex during metaphase to the presumptive cleavage furrow just before the onset of furrowing, and that Ca2+ stores with IP3R microinjected into dividing newt eggs moved toward the presumptive cleavage furrow during anaphase-cytokinesis in a microtubule-dependent manner, and that Ca2+ store-enriched microsome fractions induced the cleavage furrow as the putative cleavage stimulus. Because the distribution of F-actin and Ca2+ stores with IP3R during metaphase to cytokinesis is similar, we considered that this cortical actin flow may be powered by transportation of Ca2+ stores with IP3R. Purified F-actin labeled with phalloidin-rhodamine was microinjected into the dividing newt eggs and the eggs observed under a confocal microscope. We found that the microinjected F-actin moved linearly toward the next cleavage furrow and that this movement was blocked by nocodazole, microtubule-depolarizing agent and AMP-PNP, a blocking agent of microtubule motors. Co-microinjected rhodamine-labeled F-actin and sacro/endoplasmic reticulum Ca2+-ATPase (SERCA)-GFP-labeled Ca2+ stores with IP3R co-moved and co-accumulated to the next cleavage furrow. These results strongly suggest that Ca2+ stores with IP3R, which is transferred by microtubule-based motility as cleavage stimulus, act as an F-actin translocator.

MeSH terms

  • Actins / metabolism*
  • Actins / pharmacology
  • Animals
  • Calcium / metabolism
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Cell Cycle / drug effects
  • Cell Cycle / physiology
  • Cell Division / drug effects
  • Cell Division / physiology*
  • Coloring Agents
  • Cytokinesis / drug effects
  • Cytokinesis / physiology
  • Cytoplasm / drug effects
  • Cytoplasm / metabolism
  • Cytoplasm / ultrastructure
  • Cytoplasmic Streaming / drug effects
  • Cytoplasmic Streaming / physiology
  • Inositol 1,4,5-Trisphosphate Receptors / metabolism*
  • Microinjections / methods
  • Microscopy, Confocal
  • Microtubules / drug effects
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Molecular Motor Proteins / drug effects
  • Molecular Motor Proteins / metabolism*
  • Ovum / drug effects
  • Ovum / metabolism
  • Ovum / ultrastructure
  • Phalloidine
  • Rhodamines
  • Salamandridae
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / metabolism
  • Tubulin Modulators / pharmacology

Substances

  • Actins
  • Coloring Agents
  • Inositol 1,4,5-Trisphosphate Receptors
  • Molecular Motor Proteins
  • Rhodamines
  • Tubulin Modulators
  • Phalloidine
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • Calcium