Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
PLoS Biol. 2009 Dec;7(12):e1000256. doi: 10.1371/journal.pbio.1000256. Epub 2009 Dec 15.
A single nucleotide substitution in intron 3 of IGF2 in pigs abrogates a binding site for a repressor and leads to a 3-fold up-regulation of IGF2 in skeletal muscle. The mutation has major effects on muscle growth, size of the heart, and fat deposition. Here, we have identified the repressor and find that the protein, named ZBED6, is previously unknown, specific for placental mammals, and derived from an exapted DNA transposon. Silencing of Zbed6 in mouse C2C12 myoblasts affected Igf2 expression, cell proliferation, wound healing, and myotube formation. Chromatin immunoprecipitation (ChIP) sequencing using C2C12 cells identified about 2,500 ZBED6 binding sites in the genome, and the deduced consensus motif gave a perfect match with the established binding site in Igf2. Genes associated with ZBED6 binding sites showed a highly significant enrichment for certain Gene Ontology classifications, including development and transcriptional regulation. The phenotypic effects in mutant pigs and ZBED6-silenced C2C12 myoblasts, the extreme sequence conservation, its nucleolar localization, the broad tissue distribution, and the many target genes with essential biological functions suggest that ZBED6 is an important transcription factor in placental mammals, affecting development, cell proliferation, and growth.
猪 IGF2 基因内含子 3 中的单个核苷酸替换破坏了一个抑制因子的结合位点，导致骨骼肌中 IGF2 的表达上调 3 倍。该突变对肌肉生长、心脏大小和脂肪沉积有重大影响。在这里，我们已经鉴定出了这个抑制因子，它被命名为 ZBED6，是一种以前未知的、专门针对胎盘哺乳动物的蛋白，来源于一个外显子转座子。在小鼠 C2C12 成肌细胞中沉默 Zbed6 会影响 Igf2 的表达、细胞增殖、伤口愈合和肌管形成。使用 C2C12 细胞进行的染色质免疫沉淀 (ChIP) 测序在基因组中鉴定出大约 2500 个 ZBED6 结合位点，推断出的保守基序与 Igf2 中的已建立的结合位点完全匹配。与 ZBED6 结合位点相关的基因与某些基因本体分类具有高度显著的富集，包括发育和转录调控。在突变猪和 ZBED6 沉默的 C2C12 成肌细胞中的表型效应、极端的序列保守性、核仁定位、广泛的组织分布以及许多具有重要生物学功能的靶基因表明，ZBED6 是胎盘哺乳动物中的一个重要转录因子，影响发育、细胞增殖和生长。
