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Actin Related Protein

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Masahiko Harata – One of the best experts on this subject based on the ideXlab platform.

  • The linker histone in Saccharomyces cerevisiae interacts with ActinRelated Protein 4 and both regulate chromatin structure and cellular morphology.
    The International Journal of Biochemistry & Cell Biology, 2014
    Co-Authors: Milena Georgieva, Masahiko Harata, Dessislava Staneva, Katya Uzunova, Toni Efremov, Konstantin Balashev, George Miloshev

    Abstract:

    Chromatin structure promotes important epigenetic mechanisms that regulate cellular fate by organizing, preserving and controlling the way by which the genetic information works. Our understanding of chromatin and its functions is sparse and not yet well defined. The uncertainty comes from the complexity of chromatin and is induced by the existence of a large number of nuclear Proteins that influence it. The intricate interaction among all these structural and functional nuclear Proteins has been under extensive study in the recent years. Here, we show that Saccharomyces cerevisiae linker histone physically interacts with Arp4p (ActinRelated Protein 4) which is a key subunit of three chromatin modifying complexes – INO80, SWR1 and NuA4. A single – point mutation in the Actin – fold domain of Arp4p together with the knock-out of the gene for the linker histone in S. cerevisiae severely abrogates cellular and nuclear morphology and leads to complete disorganizing of the higher levels of chromatin organization.

  • dna binding properties of the Actin Related Protein arp8 and its role in dna repair
    PLOS ONE, 2014
    Co-Authors: Akihisa Osakabe, Yuichiro Takahashi, Hirokazu Murakami, Kenji Otawa, Hiroaki Tachiwana, Hitoshi Nishijima, Kei Ich Shibahara, Hitoshi Kurumizaka, Masahiko Harata

    Abstract:

    Actin and ActinRelated Proteins (Arps), which are members of the Actin family, are essential components of many of these remodeling complexes. Actin, Arp4, Arp5, and Arp8 are found to be evolutionarily conserved components of the INO80 chromatin remodeling complex, which is involved in transcriptional regulation, DNA replication, and DNA repair. A recent report showed that Arp8 forms a module in the INO80 complex and this module can directly capture a nucleosome. In the present study, we showed that recombinant human Arp8 binds to DNAs, and preferentially binds to single-stranded DNA. Analysis of the binding of adenine nucleotides to Arp8 mutants suggested that the ATP-binding pocket, located in the evolutionarily conserved Actin fold, plays a regulatory role in the binding of Arp8 to DNA. To determine the cellular function of Arp8, we derived tetracycline-inducible Arp8 knockout cells from a cultured human cell line. Analysis of results obtained after treating these cells with aphidicolin and camptothecin revealed that Arp8 is involved in DNA repair. Together with the previous observation that Arp8, but not γ-H2AX, is indispensable for recruiting INO80 complex to DSB in human, results of our study suggest an individual role for Arp8 in DNA repair.

  • Nuclear Actin filaments recruit cofilin and ActinRelated Protein 3, and their formation is connected with a mitotic block
    Histochemistry and Cell Biology, 2014
    Co-Authors: Alžběta Kalendová, Masahiko Harata, Ilona Kalasová, Shota Yamazaki, Lívia Uličná, Pavel Hozák

    Abstract:

    Although Actin monomers polymerize into filaments in the cytoplasm, the form of Actin in the nucleus remains elusive. We searched for the form and function of β-Actin fused to nuclear localization signal and to enhanced yellow fluorescent Protein (EN-Actin). Our results reveal that EN-Actin is either dispersed in the nucleoplasm (homogenous EN-Actin) or forms bundled filaments in the nucleus (EN-Actin filaments). Formation of such filaments was not connected with increased EN-Actin levels. Among numerous Actin-binding Proteins tested, only cofilin is recruited to the EN-Actin filaments. Overexpression of EN-Actin causes increase in the nuclear levels of ActinRelated Protein 3 (Arp3). Although Arp3, a member of Actin nucleation complex Arp2/3, is responsible for EN-Actin filament nucleation and bundling, the way cofilin affects nuclear EN-Actin filaments dynamics is not clear. While cells with homogenous EN-Actin maintained unaffected mitosis during which EN-Actin re-localizes to the plasma membrane, generation of nuclear EN-Actin filaments severely decreases cell proliferation and interferes with mitotic progress. The introduction of EN-Actin manifests in two mitotic-inborn defects—formation of binucleic cells and generation of micronuclei—suggesting that cells suffer aberrant cytokinesis and/or impaired chromosomal segregation. In interphase, nuclear EN-Actin filaments passed through chromatin region, but do not co-localize with either chromatin remodeling complexes or RNA polymerases I and II. Surprisingly presence of EN-Actin filaments was connected with increase in the overall transcription levels in the S-phase by yet unknown mechanism. Taken together, EN-Actin can form filaments in the nucleus which affect important cellular processes such as transcription and mitosis.

Ulrike Wintersberger – One of the best experts on this subject based on the ideXlab platform.

  • the nuclear Actin Related Protein act3p arp4p is involved in the dynamics of chromatin modulating complexes
    Yeast, 2005
    Co-Authors: Rie Sunada, Ulrike Wintersberger, Irene Gorzer, Takahito Yoshida, Noriyuki Suka, Masahiko Harata

    Abstract:

    Chromatin remodelling and histone-modifying complexes govern the modulation of chromatin structure. While components of these complexes are diverse, nuclear ActinRelated Proteins (Arps) have been repeatedly found in these complexes from yeast to mammals. In most cases, Arps are required for functioning of the complexes, but the molecular mechanisms of nuclear Arps have as yet been largely unknown. The Arps and Actin, sharing a common ancestor, are supposed to be highly similar in the three-dimensional structure of their core regions, including the ATP-binding pocket. The Arp Act3p/Arp4p of Saccharomyces cerevisiae exists within the nucleus, partly as a component of several high molecular mass complexes, including the NuA4 histone acetyltransferase (HAT) complex, and partly as uncomplexed molecules. We observed that mutations in the putative ATP-binding pocket of Act3p/Arp4p increased its concentration in the high molecular mass complexes and, conversely, that an excess of ATP or ATPγS led to the release of wild-type Act3p/Arp4p from the complexes. These results suggest a requirement of ATP binding by Act3p/Arp4p for its dissociation from the complexes. In accordance, a mutation in the putative ATP binding site of Act3p/Arp4p inhibited the conversion of the NuA4 complex into the smaller piccoloNuA4, which does not contain Act3p/Arp4p and exhibits HAT activity distinct from that of NuA4. Although the in vitro binding activity of ATP by recombinant Act3p/Arp4p was found to be rather weak, our observations, taken together, suggest that the ATP-binding pocket of Act3p/Arp4p is involved in the function of chromatin modulating complexes by regulating their dynamics. Copyright © 2005 John Wiley & Sons, Ltd.

  • The nuclear ActinRelated Protein Act3p/Arp4p is involved in the dynamics of chromatin-modulating complexes†
    Yeast, 2005
    Co-Authors: Rie Sunada, Ulrike Wintersberger, Irene Gorzer, Takahito Yoshida, Noriyuki Suka, Masahiko Harata

    Abstract:

    Chromatin remodelling and histone-modifying complexes govern the modulation of chromatin structure. While components of these complexes are diverse, nuclear ActinRelated Proteins (Arps) have been repeatedly found in these complexes from yeast to mammals. In most cases, Arps are required for functioning of the complexes, but the molecular mechanisms of nuclear Arps have as yet been largely unknown. The Arps and Actin, sharing a common ancestor, are supposed to be highly similar in the three-dimensional structure of their core regions, including the ATP-binding pocket. The Arp Act3p/Arp4p of Saccharomyces cerevisiae exists within the nucleus, partly as a component of several high molecular mass complexes, including the NuA4 histone acetyltransferase (HAT) complex, and partly as uncomplexed molecules. We observed that mutations in the putative ATP-binding pocket of Act3p/Arp4p increased its concentration in the high molecular mass complexes and, conversely, that an excess of ATP or ATPγS led to the release of wild-type Act3p/Arp4p from the complexes. These results suggest a requirement of ATP binding by Act3p/Arp4p for its dissociation from the complexes. In accordance, a mutation in the putative ATP binding site of Act3p/Arp4p inhibited the conversion of the NuA4 complex into the smaller piccoloNuA4, which does not contain Act3p/Arp4p and exhibits HAT activity distinct from that of NuA4. Although the in vitro binding activity of ATP by recombinant Act3p/Arp4p was found to be rather weak, our observations, taken together, suggest that the ATP-binding pocket of Act3p/Arp4p is involved in the function of chromatin modulating complexes by regulating their dynamics. Copyright © 2005 John Wiley & Sons, Ltd.

  • the nuclear Actin Related Protein act3p arp4p of saccharomyces cerevisiae is involved in transcription regulation of stress genes
    Molecular Microbiology, 2003
    Co-Authors: Irene Gorzer, Christoph Schuller, Erich Heidenreich, Ludmila Krupanska, Karl Kuchler, Ulrike Wintersberger

    Abstract:

    Summary

    A mutational analysis of the essential nuclear ActinRelated Protein of Saccharomyces cerevisiae, Act3p/Arp4p, was performed. The five residues chosen for substitution were amino acids conserved between Actin and Act3p/Arp4p, the tertiary structure of which most probably resembles that of Actin. Two thermosensitive (ts) mutants, a single and a double point mutant, and one lethal double point mutant were obtained. Both ts mutants were formamide-sensitive which supports a structural Relatedness of Act3p/Arp4p to Actin; they were also hypersensitive against hydroxyurea and ultraviolet irradiation pointing to a possible role of Act3p/Arp4p in DNA replication and repair. Their ‘suppressor of Ty’ (SPT) phenotype, ob-served with another ts mutant of Act3p/Arp4p before, suggested involvement of Act3p/Arp4p in transcription regulation. Accordingly, genome-wide expression profiling revealed misregulated transcription in a ts mutant of a number of genes, among which increased expression of various stress-responsive genes (many of them requiring Msn2p/Msn4p for induction) was the most salient result. This provides an explanation for the mutant’s enhanced resistance to severe thermal and oxidative stress. Thus, Act3p/Arp4p takes an important part in the repression of stress-induced genes under non-stress conditions.

Katsuhiko Nishimori – One of the best experts on this subject based on the ideXlab platform.

  • the brain specific Actin Related Protein arpnα interacts with the transcriptional co repressor ctbp
    Biochemical and Biophysical Research Communications, 2003
    Co-Authors: Katsuhiko Nishimori, Masahiko Harata

    Abstract:

    Abstract ActinRelated Protein (Arp) is found in many chromatin remodeling and histone acetyltransferase complexes. We previously identified ArpNα as an isoform of ArpNβ/BAF53, which is included in mammalian SWI/SNF chromatin remodeling complex, and showed that ArpNα is a potential component of the complex. Although it has a structure highly similar to ArpNβ/BAF53, ArpNα is expressed exclusively in brain and in neural differentiated embryonal carcinoma cells. Since ArpNα possesses a region that shows low similarity to ArpNβ/BAF53, we hypothesized that Proteins interActing with this region contribute to the ArpNα-specific function in brain. Here we showed that ArpNα, but not ArpNβ/BAF53, interacts with the transcriptional co-repressor CtBP (C-terminal binding Protein). Transactivation by the SWI/SNF complex and glucocorticoid receptor was repressed by the CtBP in the presence of ArpNα. These findings suggest that SWI/SNF complex containing ArpNα might regulate certain genes involved in brain development and/or its function differently from SWI/SNF complex containing ArpNβ/BAF53.

  • brain specific expression of the nuclear Actin Related Protein arpnα and its involvement in mammalian swi snf chromatin remodeling complex
    Biochemical and Biophysical Research Communications, 2002
    Co-Authors: Yukiko Kuroda, Katsuhiko Nishimori, Tsutomu Ohta, Masahiko Harata

    Abstract:

    Abstract ActinRelated Proteins share significant homology with conventional Actins and are classified into subfamilies based on the similarity of their sequences and functions. The Arp4 subfamily of Arps is localized in the nucleus, and a mammalian isoform, ArpNβ (also known as BAF53), is a component of the chromatin remodeling and histone acetyltransferase complexes. Another isoform identified in humans, ArpNα has scarcely been characterized yet. We identified mouse ArpNα, and showed that ArpNα is more similar between humans and mice than ArpNβ. No difference was observed between ArpNα and β in subcellular localization and interaction with BRM, which is an ATPase subunit of mammalian SWI/SNF chromatin remodeling complex. However, ArpNα was expressed exclusively in the brain and its expression was induced during neural differentiation of P19 mouse embryonic carcinoma cells. ArpNα is the first brain-specific component of a chromatin remodeling complex to be identified, suggesting that ArpNα has conserved and important roles in the differentiation of neural cells through regulation of chromatin structure.

  • Brain-specific expression of the nuclear ActinRelated Protein ArpNα and its involvement in mammalian SWI/SNF chromatin remodeling complex
    Biochemical and Biophysical Research Communications, 2002
    Co-Authors: Yukiko Kuroda, Katsuhiko Nishimori, Tsutomu Ohta, Masahiko Harata

    Abstract:

    Abstract ActinRelated Proteins share significant homology with conventional Actins and are classified into subfamilies based on the similarity of their sequences and functions. The Arp4 subfamily of Arps is localized in the nucleus, and a mammalian isoform, ArpNβ (also known as BAF53), is a component of the chromatin remodeling and histone acetyltransferase complexes. Another isoform identified in humans, ArpNα has scarcely been characterized yet. We identified mouse ArpNα, and showed that ArpNα is more similar between humans and mice than ArpNβ. No difference was observed between ArpNα and β in subcellular localization and interaction with BRM, which is an ATPase subunit of mammalian SWI/SNF chromatin remodeling complex. However, ArpNα was expressed exclusively in the brain and its expression was induced during neural differentiation of P19 mouse embryonic carcinoma cells. ArpNα is the first brain-specific component of a chromatin remodeling complex to be identified, suggesting that ArpNα has conserved and important roles in the differentiation of neural cells through regulation of chromatin structure.