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.
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.
Mitsuyama
Fuyuki
F
Department of Neurosurgery, Fujita Health University, Toyoake, Aichi, Japan. fmituyam@hotmail.com
Futatsugi
Yoshio
Y
Okuya
Masato
M
Karagiozov
Kostadin
K
Kato
Yoko
Y
Kanno
Tetsuo
T
Sano
Hirotoshi
H
Koide
Tadashi
T
Sawai
Tsuyosi
T
D000199:Actins / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D004396:Coloring Agents; D048749:Cytokinesis / Q000187:drug effects / Q000502:physiology; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003595:Cytoplasmic Streaming / Q000187:drug effects / Q000502:physiology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D008845:Microinjections / Q000379:methods; D018613:Microscopy, Confocal; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D020409:Molecular Motor Proteins / Q000187:drug effects / Q000378:metabolism*; D010063:Ovum / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010590:Phalloidine; D012235:Rhodamines; D012455:Salamandridae; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D050257:Tubulin Modulators / Q000494:pharmacology
D000199:Actins; D004396:Coloring Agents; D053496:Inositol 1,4,5-Trisphosphate Receptors; D020409:Molecular Motor Proteins; D012235:Rhodamines; D050257:Tubulin Modulators; D010590:Phalloidine; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium