Sakurai Toshihiro, Sakamoto Atsushi, Muroi Yoshikage, Bai Hanako, Nagaoka Kentaro, Tamura Kazuhiro, Takahashi Toru, Hashizume Kazuyoshi, Sakatani Miki, Takahashi Masashi, Godkin James D, Imakawa Kazuhiko
Laboratory of Animal Breeding, Veterinary Medical Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Biol Reprod. 2009 Jun;80(6):1223-31. doi: 10.1095/biolreprod.108.073916. Epub 2009 Feb 11.
Interferon tau gene (IFNT) is expressed only by mononuclear trophectoderm cells in ruminant ungulates. To our knowledge, its epigenetic regulation and interaction with trophectoderm lineage-specific caudal-related homeobox 2 transcription factor (CDX2) have not been characterized. Herein, we studied differences in chromatin structures and transcription of endogenous bovine IFNT in bovine trophoblast BT-1 and CT-1 cells and in nontrophoblast MDBK cells. Transcripts from endogenous IFNT and CDX2 genes were found in BT-1 and CT-1 cells but not in MDBK cells. Chromatin immunoprecipitation study revealed that CDX2 binding sites exist in proximal upstream regions of IFNT (IFN-tau-c1). Endogenous IFNT transcription in BT-1 cells was increased with CDX2 overexpression but was reduced with short interfering RNA specific for the CDX2 transcript. In chromatin immunoprecipitation studies, histone H3K18 acetylation of IFNT was higher in CT-1 cells than in MDBK cells, while histone H3K9 methylation was lower in CT-1 cells than in nontrophoblast cells. In MDBK cells (but not in CT-1 cells), histone deacetylases were bound to IFNT, which was reversed with trichostatin A treatment; treatment with trichostatin A and CDX2 then increased IFNT mRNA levels that resulted from abundant CDX2 mRNA expression. These data provide evidence that significant increase in endogenous IFNT transcription in MDBK cells (which do not normally express IFNT) can be induced through CDX2 overexpression and high H3K18 acetylation, but lowering of H3K9 methylation could also be required for the degree of IFNT transcription seen in trophoblast cells.
干扰素τ基因（IFNT）仅在反刍有蹄类动物的单核滋养外胚层细胞中表达。据我们所知，其表观遗传调控以及与滋养外胚层谱系特异性尾相关同源框2转录因子（CDX2）的相互作用尚未得到表征。在此，我们研究了内源性牛IFNT在牛滋养层BT - 1和CT - 1细胞以及非滋养层MDBK细胞中的染色质结构和转录差异。在内源性IFNT和CDX2基因的转录本在BT - 1和CT - 1细胞中被发现，但在MDBK细胞中未发现。染色质免疫沉淀研究表明，IFNT（IFN - tau - c1）近端上游区域存在CDX2结合位点。BT - 1细胞中的内源性IFNT转录随着CDX与CDX2转录本特异性的短发夹RNA降低。在染色质免疫沉淀研究中，IFNT的组蛋白H3K18乙酰化在CT - 1细胞中高于MDBK细胞，而组蛋白H3K9甲基化在CT - 1细胞中低于非滋养层细胞。在MDBK细胞（而非CT - 1细胞）中，组蛋白去乙酰化酶与IFNT结合，曲古抑菌素A处理可使其逆转；曲古抑菌素A和CDX2处理随后增加了由丰富的CDX2 mRNA表达导致的IFNT mRNA水平。这些数据提供了证据，即通过CDX2过表达和高H3K18乙酰化可诱导MDBK细胞（通常不表达IFNT）中内源性IFNT转录显著增加，但对于滋养层细胞中所见的IFNT转录程度，降低H3K9甲基化可能也是必需的。
