Identification of a nuclear protein ArpN as a component of human SWI/SNF complex and its selective association with a subset of active genes.
The hSWI/SNF complex remodels the chromatin structure to modulate gene expression. The hSWI/SNF complex is a multiprotein complex with at least 10 different proteins in mammals. In this study, we identified the 45 kDa subunit of the hSWI/SNF complex as ArpN, an actin-related protein. ArpN has a 36% identity and 50% similarity with the human beta-actin, but cannot be classified into any known class of actin-related proteins. ArpN is exclusively localized within the nucleus and appears as the unbound, chromatin-associated, or nuclear matrix associated forms in the nucleus. In the chromatin immunoprecipitation (ChIP) assay, we found the associations of ArpN with the Ets-2 and c-mycP2 promoter regions in HeLa cells. The promoter regions of the hsp70, cyclophilin, beta-globin, TdT, and cd4 genes, however, were not associated with ArpN. The Ets-2 and c-mycP2 genes are expressed actively in HeLa cells, but beta-globin, TdT, and cd4 genes are inactive. The hsp70 and cyclophilin genes have a feature of stress-inducibility. These selective associations of ArpN with a subset of active genes support the proposition that the requirement of hSWI/SNF complex in gene activation is gene specific.
Department of Neuroscience, Graduate School of East-West Medical Science, Kyung Hee University, Seoul, Korea.
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Sung
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Choi
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Kwon
D000199:Actins; D000595:Amino Acid Sequence; D002843:Chromatin / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D015870:Gene Expression / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology*; D014162:Transfection
C116160:ACTL6A protein, human; D000199:Actins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; C089969:snf protein, Drosophila