Division of Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
Blood. 2011 Jul 28;118(4):1145-53. doi: 10.1182/blood-2010-10-315275. Epub 2011 May 31.
ERG is a member of the ETS transcription factor family that is highly enriched in endothelial cells (ECs). To further define the role of ERG in regulating EC function, we evaluated the effect of ERG knock-down on EC lumen formation in 3D collagen matrices. Blockade of ERG using siRNA completely interferes with EC lumen formation. Quantitative PCR (QPCR) was used to identify potential downstream gene targets of ERG. In particular, we identified RhoJ as the Rho GTPase family member that is closely related to Cdc42 as a target of ERG. Knockdown of ERG expression in ECs led to a 75% reduction in the expression of RhoJ. Chromatin immunoprecipitation and transactivation studies demonstrated that ERG could bind to functional sites in the proximal promoter of the RhoJ gene. Knock-down of RhoJ similarly resulted in a marked reduction in the ability of ECs to form lumens. Suppression of either ERG or RhoJ during EC lumen formation was associated with a marked increase in RhoA activation and a decrease in Rac1 and Cdc42 activation and their downstream effectors. Finally, in contrast to other Rho GTPases, RhoJ exhibits a highly EC-restricted expression pattern in several different tissues, including the brain, heart, lung, and liver.
ERG 是 ETS 转录因子家族的成员，在血管内皮细胞（ECs）中高度富集。为了进一步确定 ERG 在调节 EC 功能中的作用，我们评估了 ERG 敲低对 3D 胶原基质中 EC 管腔形成的影响。使用 siRNA 阻断 ERG 完全干扰了 EC 管腔形成。定量 PCR（QPCR）用于鉴定 ERG 的潜在下游基因靶标。特别是，我们鉴定出 RhoJ 作为 Rho GTPase 家族成员，与 Cdc42 密切相关，是 ERG 的靶标。在 EC 中敲低 ERG 表达导致 RhoJ 的表达减少 75%。染色质免疫沉淀和转激活研究表明，ERG 可以结合 RhoJ 基因近端启动子中的功能位点。RhoJ 的敲低同样导致 EC 形成管腔的能力明显降低。在 EC 管腔形成过程中抑制 ERG 或 RhoJ 与 RhoA 激活的明显增加以及 Rac1 和 Cdc42 激活及其下游效应物的减少有关。最后，与其他 Rho GTPases 不同，RhoJ 在包括大脑、心脏、肺和肝脏在内的几种不同组织中表现出高度局限于 EC 的表达模式。
