title: Involvement of a short interspersed element in epigenetic transcriptional silencing of the amoebapore gene in Entamoeba histolytica.
abstract: Transcriptional silencing of an amoebapore (ap-a) gene occurred in Entamoeba histolytica following the transfection of plasmids containing a DNA segment (473 bp) homologous to the 5' upstream region of the gene (R. Bracha, Y. Nuchamowitz, and D. Mirelman, Eukaryot. Cell 2:295-305, 2003). This segment contains the promoter region of the ap-a gene, a T-rich stretch, followed by a truncated SINE1 (short interspersed element 1) that is transcribed from the antisense strand. Transfection of plasmids containing truncated SINE1 sequences which lack their 3' regulatory elements upstream of the ap-a gene was essential for the downstream silencing of the ap-a gene while transfection with plasmids containing the entire SINE1 sequence or without the T-rich stretch promoted the overexpression of the ap-a gene. Both the T-rich stretch and sequences of the 5' SINE1 were essential for the transcription of SINE1. RNA extracts from gene-silenced cultures showed small amounts of short (approximately 140-nucleotide), single-stranded molecules with homology to SINE1 but no short interfering RNA. Chromatin immunoprecipitation analysis with an antibody against methylated K4 of histone H3 showed a demethylation of K4 at the domain of the ap-a gene, indicating transcriptional inactivation. These results suggest the involvement of SINE1 in triggering the gene silencing and the role of histone modification in its epigenetic maintenance.
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Anbar
authors.forename: Rivka
authors.initials: R
authors.lastname: Bracha
authors.forename: Yael
authors.initials: Y
authors.lastname: Nuchamowitz
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Anat
authors.initials: A
authors.lastname: Florentin
authors.forename: David
authors.initials: D
authors.lastname: Mirelman
mesh_terms: D000818:Animals; D003596:Cytosine / Q000378:metabolism; D004748:Entamoeba histolytica / Q000235:genetics* / Q000502:physiology; D044127:Epigenesis, Genetic; D020868:Gene Silencing; D017930:Genes, Reporter; D006657:Histones / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics* / Q000378:metabolism; D016366:Open Reading Frames; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000235:genetics / Q000378:metabolism; D020086:Short Interspersed Nucleotide Elements; D014158:Transcription, Genetic
chemical_list: D006657:Histones; D007473:Ion Channels; D015800:Protozoan Proteins; C041670:amoebapore proteins, protozoan; D012313:RNA; D003596:Cytosine