title: The actin-related protein hArp8 accumulates on the mitotic chromosomes and functions in chromosome alignment.
abstract: The actin family consists of conventional actin and various actin-related proteins (Arps). Some of these Arps are localized in the nucleus, and a fraction of each of these nuclear Arps is functionally involved in chromatin remodeling and histone acetyltransferase complexes. On the other hand, in mitotic cells, the localization and function of the nuclear Arps are largely unknown. Human Arp8 (hArp8), an ortholog of yeast nuclear Arp8, was recently found to be associated with the hINO80-chromatin remodeling complex along with hArp5. Here we report that hArp8, but not hArp5, accumulates on mitotic chromosomes. This is the first example where a member of the actin family is found to be associated with mitotic chromosomes. Expression of truncated hArp8 proteins and depletion of endogenous hArp8 by RNA interference caused misalignment of mitotic chromosomes, suggesting that chromosome-associated hArp8 has a role in chromosome behavior. In contrast, depletion of hIno80 and hArp5 did not cause misalignment of chromosomes, suggesting that the role of hArp8 at mitotic chromosomes is independent of the activity of hINO80 complexes. These findings provide the first insight into a novel function of actin family members in mitosis.
authors.affiliation: Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Aoyama
authors.forename: Asako
authors.initials: A
authors.lastname: Oka
authors.forename: Kumiko
authors.initials: K
authors.lastname: Kitayama
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Harata
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D033481:Chromosomes, Mammalian / Q000737:chemistry / Q000502:physiology*; D004265:DNA Helicases / Q000502:physiology; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D008840:Microfilament Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D008938:Mitosis / Q000235:genetics*; D017434:Protein Structure, Tertiary; D034622:RNA Interference
chemical_list: C527779:ACTR8 protein, human; D004268:DNA-Binding Proteins; D008840:Microfilament Proteins; D000074183:ATPases Associated with Diverse Cellular Activities; D004265:DNA Helicases; C524421:INO80 protein, human