The redistribution of Ca2+ stores with inositol 1,4,5-trisphosphate receptor to the cleavage furrow in a microtubule-dependent manner.
We reported that microinjection of Ca2+ store-enriched microsome fractions from cultured CHO cells and mouse cerebella to dividing newt eggs induced extra-cleavage furrows via inositol 1,4,5-trisphosphate-induced Ca2+ release (Mitsuyama et al., 1999). Our observation strongly suggested that Ca2+ stores with inositol 1,4,5-trisphosphate receptor (IP3R) induce and position a cleavage furrow, as Ca2+-releasing machinery, and that such is itself a putative cleavage stimulus. For confirmation, we immunocytochemically examined mitotic CHO cells using antibodies against Ca2+ store-related proteins. We found that polar dominant Ca2+ stores with IP3R during metaphase were re-distributed to the future cleavage cortex just preceding the onset of furrowing, and that this redistributing IP3R was present on microtubule bundles. When a microsome fraction from sacro/endoplasmic reticulum Ca2+-ATPase (SERCA)-GFP stably expressing CHO cells was microinjected into dividing newt eggs and observed by confocal microscopy, the microinjected Ca2+ stores with IP3R moved linearly toward the next cleavage furrow and this movement was blocked by nocodazole, a microtubule-depolarizing agent, but not by cytochalasin B, an F-actin-depolarizing agent. These observations strongly suggest that Ca2+ stores with IP3R are transferred and accumulate to the cleavage furrow by microtubule-based motility, as a cleavage stimulus.
Mitsuyama
F
F
Developmental Neurobiology Laboratory, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama, Japan. fmituyam@f2.dion.ne.jp
Sawai
T
T
D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D006224:Cricetinae; D003571:Cytochalasin B / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000201:enzymology; D053496:Inositol 1,4,5-Trisphosphate Receptors; D051379:Mice; D008845:Microinjections; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000502:physiology*; D008938:Mitosis; D015739:Nocodazole / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012455:Salamandridae
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D003571:Cytochalasin B; D000252:Calcium-Transporting ATPases; D015739:Nocodazole; D002118:Calcium