title: Actin Family Proteins in the Human INO80 Chromatin Remodeling Complex Exhibit Functional Roles in the Induction of Heme Oxygenase-1 with Hemin.
abstract: Nuclear actin family proteins, comprising of actin and actin-related proteins (Arps), are essential functional components of the multiple chromatin remodeling complexes. The INO80 chromatin remodeling complex, which is evolutionarily conserved and has roles in transcription, DNA replication and repair, consists of actin and actin-related proteins Arp4, Arp5, and Arp8. We generated Arp5 knockout (KO) and Arp8 KO cells from the human Nalm-6 pre-B cell line and used these KO cells to examine the roles of Arp5 and Arp8 in the transcriptional regulation mediated by the INO80 complex. In both of Arp5 KO and Arp8 KO cells, the oxidative stress-induced expression ofHMOX1gene, encoding for heme oxygenase-1 (HO-1), was significantly impaired. Consistent with these observations, chromatin immunoprecipitation (ChIP) assay revealed that oxidative stress caused an increase in the binding of the INO80 complex to the regulatory sites ofHMOX1in wild-type cells. The binding of INO80 complex to chromatin was reduced in Arp8 KO cells compared to that in the wild-type cells. On the other hand, the binding of INO80 complex to chromatin in Arp5 KO cells was similar to that in the wild-type cells even under the oxidative stress condition. However, both remodeling of chromatin at theHMOX1regulatory sites and binding of a transcriptional activator to these sites were impaired in Arp5 KO cells, indicating that Arp5 is required for the activation of the INO80 complex. Collectively, these results suggested that these nuclear Arps play indispensable roles in the function of the INO80 chromatin remodeling complex.
authors.affiliation: Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University Sendai, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University Sendai, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Murakami
authors.affiliation: Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University Sendai, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Akiyama
authors.affiliation: Department of Biochemistry, Graduate School of Medicine, Tohoku University Sendai, Japan.
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Katoh
authors.affiliation: Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University Sendai, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Oma
authors.affiliation: Department of Integrated Genetics, National Institute of GeneticsMishima, Japan; Division of Molecular Immunology, Institute of Advanced Medical Sciences, Tokushima UniversityTokushima, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nishijima
authors.affiliation: Department of Integrated Genetics, National Institute of Genetics Mishima, Japan.
authors.forename: Kei-Ichi
authors.initials: KI
authors.lastname: Shibahara
authors.affiliation: Department of Biochemistry, Graduate School of Medicine, Tohoku UniversitySendai, Japan; Japan Agency for Medical Research and DevelopmentTokyo, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Igarashi
authors.affiliation: Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University Sendai, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Harata
keywords: actin family; chromatin; chromatin remodeling; heme oxygenase-1; stress response