Ishibashi Riki, Kozuki Satoshi, Kamakura Sachiko, Sumimoto Hideki, Toyoshima Fumiko
From the Department of Cell Biology, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan, the Department of Mammalian Regulatory Networks, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan, and.
the Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan.
J Biol Chem. 2016 Feb 12;291(7):3333-45. doi: 10.1074/jbc.M115.679563. Epub 2015 Dec 22.
Inscuteable (Insc) regulates cell fate decisions in several types of stem cells. Although it is recognized that the expression levels of mouse INSC govern the balance between symmetric and asymmetric stem cell division, regulation of mouse Insc gene expression remains poorly understood. Here, we showed that mouse Insc expression transiently increases at an early stage of differentiation, when mouse embryonic stem (mES) cells differentiate into bipotent mesendoderm capable of producing both endoderm and mesoderm in defined culture conditions. We identified the minimum transcriptional regulatory element (354 bases) that drives mouse Insc transcription in mES cells within a region >5 kb upstream of the mouse Insc transcription start site. We found that the transcription factor reticuloendotheliosis oncogene (c-Rel) bound to the minimum element and promoted mouse Insc expression in mES cells. In addition, short interfering RNA-mediated knockdown of either mouse INSC or c-Rel protein decreased mesodermal cell populations without affecting differentiation into the mesendoderm or endoderm. Furthermore, overexpression of mouse INSC rescued the mesoderm-reduced phenotype induced by knockdown of c-Rel. We propose that regulation of mouse Insc expression by c-Rel modulates cell fate decisions during mES cell differentiation.
难以捉摸蛋白（Inscuteable，Insc）在多种类型的干细胞中调控细胞命运决定。尽管人们认识到小鼠INSC的表达水平决定了对称和不对称干细胞分裂之间的平衡，但对小鼠Insc基因表达的调控仍知之甚少。在此，我们发现当小鼠胚胎干细胞（mES细胞）在特定培养条件下分化为能够产生内胚层和中胚层的双能中胚层时，小鼠Insc的表达在分化早期短暂增加。我们在小鼠Insc转录起始位点上游>5 kb的区域内鉴定出了驱动mES细胞中小鼠Insc转录的最小转录调控元件（354个碱基）。我们发现转录因子网状内皮增生症癌基因（c-Rel）与该最小元件结合，并促进mES细胞中小鼠Insc的表达。此外，短干扰RNA介导的小鼠INSC或c-Rel蛋白敲低减少了中胚层细胞群体，而不影响向中胚层或内胚层的分化。此外，小鼠INSC的过表达挽救了由c-Rel敲低诱导的中胚层减少表型。我们提出，c-Rel对小鼠Insc表达的调控在mES细胞分化过程中调节细胞命运决定。
