Different activity regulation and subcellular localization of LIMK1 and LIMK2 during cell cycle transition.
LIM kinases (LIMK1 and LIMK2) regulate actin cytoskeletal reorganization through phosphorylating and inactivating cofilin, an actin-depolymerizing factor of actin filaments. Here, we describe a detailed analysis of the cell-cycle-dependent activity of LIMK2, and a subcellular localization of LIMK1 and LIMK2. The activity of LIMK2, distinct from LIMK1, toward cofilin phosphorylation did not change in the normal cell division cycle. In contrast, LIMK2 was hyperphosphorylated and its activity was markedly increased when HeLa cells were synchronized at mitosis with nocodazole treatment. Immunofluorescence analysis showed that LIMK1 was localized at cell-cell adhesion sites in interphase and prophase, redistributed to the spindle poles during prometaphase to anaphase, and accumulated at the cleavage furrow in telophase. In contrast, LIMK2 was diffusely localized in the cytoplasm during interphase, redistributed to the mitotic spindle, and finally to the spindle midzone during anaphase to telophase. These findings suggest that LIMK2 is activated in response to microtubule disruption, and that LIMK1 and LIMK2 may play different roles in regulating for the mitotic spindle organization, chromosome segregation, and cytokinesis during the cell division cycle.
Sumi
Tomoyuki
T
Molecular Regenerative Medicine, Department of Biochemistry and Molecular Biology, Osaka University Graduate School of Medicine, 2-2-B7 Yamadaoka, Suita, Osaka 565-0871, Japan.
Hashigasako
Atsuko
A
Matsumoto
Kunio
K
Nakamura
Toshikazu
T
D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002453:Cell Cycle / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D054461:Lim Kinases; D008870:Microtubules / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases
D051339:Actin Depolymerizing Factors; D000199:Actins; D004268:DNA-Binding Proteins; D011494:Protein Kinases; C515892:LIMK1 protein, human; C102895:LIMK2 protein, human; D054461:Lim Kinases; D017346:Protein Serine-Threonine Kinases