| Co-Investigator(Kenkyū-buntansha) |
MORIYAMA Kenji TMIMS, Department of Cell Biology, Investigator, 東京都臨床医学総合研究所, 研究員 (00250217)
AIZAWA Hiroyuki TMIMS, Department of Cell Biology, Investigator, 東京都臨床医学総合研究所, 研究員 (90221704)
ABE Hiroshi Chiba Univ., Faculty of Science, Associate Prof., 理学部, 助教授 (00222662)
YAHARA Ichiro TMIMS, Department of Cell Biology, Guest Investigator, 東京都臨床医学総合研究所, 研究員 (60109957)
ISHII Ai TMIMS, Department of Cell Biology, Investigator, 東京都臨床医学総合研究所, 研究員 (80124436)
|
|---|
| Research Abstract |
1) We improved the conventional method using fluorescently labeled actin, then demonstrated that cofilin severs actin filaments and accelerates monomer release at their pointed ends. Under substoichiometric conditions, 0.8 μM cofilin cut filamentous actin (2.2 μM) about every 270 monomer subunits and increased the depolymerization rate 5.7-fold at pH 7.1.
2) Using cultured mammalian cell and Xnopus oocyte cell extracts, we identified two proteins, which bound to actin/cofilin comuln, to be Aipl and CAP.Yeast Aip1 was also found as a factor which suppresses the ts-phenotype of cof1 mutation. In Physarum polycepharum, a heat stress-induced cist-specific actin-binding protein was identified as Aip1. Aip1 suguments both actin filaments-severing and depolymerization-accelerating activities of cofilin.
3) we identified a novel type of cofilin family member, cofilin-2, in D.discoideum. Cofilin- 2 consists of 143 amino acid residues. Cofilin-2 shows a significant homology (30.6% identity) to cof
… More
ilin-1 in its entire sequence, but does not retain some residues conserved among the cofilin family memners, suggesting that cofilin-2 belongs to a novel type of cofilin family. Purified cofilin-2 depolymerized actin filaments in a dose- and pH-dependent manner, but did not cosediment with actin filaments while cofilin-1 did. Cofilin-2 was not expressed in vegetative cells, and expresseion of coffin-2 is reduced during aggregation stage of development.
4) we investigated the role of LIM-kinase 1, a protein that phosphorylates an actin depolymerizing protein, cofilin, in semaphorin 3A-induced growth cone collapse. We found that semaphorin 3A induces phosphorylation and dephosphorylation of cofilin at growth cones sequentially. A synthetic cell-permeable peptide containing a cofilin phosphorylation site inhibited LIM-kinase in vitro and in vivo, and essentially suppressed semaphorin 3A-induced growth cone collaplse. These data suggest that phosphorylation of cofilin by LIM-kinase is a critical signaling event in growht cone collapse by semaphorin 3A. Less
|
