Department of Cell Biology and Human Anatomy, University of California, Davis, Davis, California, USA.
Institute of Pediatric Regenerative Medicine, Shriners Hospital for Children Northern California, Sacramento, California, USA.
Stem Cells. 2018 May;36(5):671-682. doi: 10.1002/stem.2776. Epub 2018 Jan 29.
Developmental Pluripotency-Associated-4 (DPPA4) is one of the few core pluripotency genes lacking clearly defined molecular and cellular functions. Here, we used a proteomics screening approach of human embryonic stem cell (hESC) nuclear extract to determine DPPA4 molecular functions through identification of novel cofactors. Unexpectedly, the signaling molecule ERBB3-binding protein 1 (EBP1) was the strongest candidate binding partner for DPPA4 in hESC. EBP1 is a growth factor signaling mediator present in two isoforms, p48 and p42. The two isoforms generally have opposing functions, however their roles in pluripotent cells have not been established. We found that DPPA4 preferentially binds p48 in pluripotent and NTERA-2 cells, but this interaction is largely absent in non-pluripotent cells and is reduced with differentiation. The DPPA4-EBP1 interaction is mediated at least in part in DPPA4 by the highly conserved SAF-A/B, Acinus and PIAS (SAP) domain. Functionally, we found that DPPA4 transcriptional repressive function in reporter assays is significantly increased by specific p48 knockdown, an effect that was abolished with an interaction-deficient DPPA4 ΔSAP mutant. Thus, DPPA4 and EBP1 may cooperate in transcriptional functions through their physical association in a pluripotent cell specific context. Our study identifies EBP1 as a novel pluripotency cofactor and provides insight into potential mechanisms used by DPPA4 in regulating pluripotency through its association with EBP1. Stem Cells 2018;36:671-682.
发育多能性相关蛋白 4（DPPA4）是少数几个核心多能性基因之一，其分子和细胞功能尚不清楚。在这里，我们使用人类胚胎干细胞（hESC）核提取物的蛋白质组学筛选方法，通过鉴定新的共因子来确定 DPPA4 的分子功能。出乎意料的是，信号分子 ERBB3 结合蛋白 1（EBP1）是 hESC 中与 DPPA4 结合最强的候选伴侣。EBP1 是一种存在于两种异构体 p48 和 p42 中的生长因子信号转导介质。这两种异构体通常具有相反的功能，但其在多能细胞中的作用尚未确定。我们发现 DPPA4 优先与多能和 NTERA-2 细胞中的 p48 结合，但这种相互作用在非多能细胞中基本不存在，并且随着分化而减少。DPPA4-EBP1 相互作用至少部分通过高度保守的 SAF-A/B、Acinus 和 PIAS（SAP）结构域介导。功能上，我们发现 DPPA4 在报告基因检测中的转录抑制功能显著增加，而特定的 p48 敲低则显著增加，这种效应在缺乏相互作用缺陷的 DPPA4 ΔSAP 突变体中被消除。因此，DPPA4 和 EBP1 可能通过在多能细胞特定环境中的物理结合在转录功能中合作。我们的研究确定了 EBP1 为一种新的多能性共因子，并提供了关于 DPPA4 通过与 EBP1 结合来调节多能性的潜在机制的见解。干细胞 2018;36:671-682。
