Stem Cell and Regeneration Thematic Research Programme, School of Biomedical Sciences, Chinese University of Hong Kong, Hong Kong, People's Republic of China.
PLoS One. 2013 Jul 23;8(7):e67896. doi: 10.1371/journal.pone.0067896. Print 2013.
BRE is a multifunctional adapter protein involved in DNA repair, cell survival and stress response. To date, most studies of this protein have been focused in the tumor model. The role of BRE in stem cell biology has never been investigated. Therefore, we have used HUCPV progenitor cells to elucidate the function of BRE. HUCPV cells are multipotent fetal progenitor cells which possess the ability to differentiate into a multitude of mesenchymal cell lineages when chemically induced and can be more easily amplified in culture. In this study, we have established that BRE expression was normally expressed in HUCPV cells but become down-regulated when the cells were induced to differentiate. In addition, silencing BRE expression, using BRE-siRNAs, in HUCPV cells could accelerate induced chondrogenic and osteogenic differentiation. Hence, we postulated that BRE played an important role in maintaining the stemness of HUCPV cells. We used microarray analysis to examine the transcriptome of BRE-silenced cells. BRE-silencing negatively regulated OCT4, FGF5 and FOXO1A. BRE-silencing also altered the expression of epigenetic genes and components of the TGF-β/BMP and FGF signaling pathways which are crucially involved in maintaining stem cell self-renewal. Comparative proteomic profiling also revealed that BRE-silencing resulted in decreased expressions of actin-binding proteins. In sum, we propose that BRE acts like an adaptor protein that promotes stemness and at the same time inhibits the differentiation of HUCPV cells.
BRE 是一种多功能衔接蛋白，参与 DNA 修复、细胞存活和应激反应。迄今为止，对该蛋白的大多数研究都集中在肿瘤模型上。BRE 在干细胞生物学中的作用从未被研究过。因此，我们使用 HUCPV 祖细胞来阐明 BRE 的功能。HUCPV 细胞是多能胎儿祖细胞，当被化学诱导时，它们具有分化为多种间充质细胞谱系的能力，并且在培养中更容易扩增。在这项研究中，我们已经确定 BRE 表达在 HUCPV 细胞中正常表达，但当细胞被诱导分化时表达下调。此外，使用 BRE-siRNAs 沉默 HUCPV 细胞中的 BRE 表达可以加速诱导的软骨和成骨分化。因此，我们假设 BRE 在维持 HUCPV 细胞的干性方面发挥着重要作用。我们使用微阵列分析来检查 BRE 沉默细胞的转录组。BRE 沉默负调控 OCT4、FGF5 和 FOXO1A。BRE 沉默还改变了表观遗传基因的表达以及 TGF-β/BMP 和 FGF 信号通路的组成部分，这些通路在维持干细胞自我更新中起着至关重要的作用。比较蛋白质组学分析还表明，BRE 沉默导致肌动蛋白结合蛋白的表达减少。总之，我们提出 BRE 作为一种衔接蛋白，促进干细胞特性，同时抑制 HUCPV 细胞的分化。
