Robaszkiewicz Agnieszka, Wiśnik Ewelina, Regdon Zsolt, Chmielewska Kinga, Virág László
Department of General Biophysics, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland.
Department of Biophysics of Environmental Pollution, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Poland.
Biochim Biophys Acta Gene Regul Mech. 2017 Dec 4. doi: 10.1016/j.bbagrm.2017.12.001.
Differentiation of human monocytes is associated with proliferation arrest resulting from activation of the inter alia retinoblastoma protein family of gene repressors, which target gene promoters in an E2F-dependent manner. To investigate RBL2 contribution to defining monocyte phenotype and function, we used primer libraries. We identified genes encoding two surface receptors (CXCR1 and IL17RE) and two TLR signaling mediators (CD86 and NFKB2) that are repressed by the RBL2-E2F4-HDAC1-BRM complex. Surprisingly, PARP1 co-regulated 24 out of the 28 identified genes controlled by RBL2. Upon RBL2 silencing, PARP1 was recruited to one subset of RBL2-dependent genes, represented by MAP2K6 and MAPK3. RBL2 silencing also restored PARP1 transcription. Gene promoters enriched in PARP1 were characterized by increased histone acetylation and the replacement of HDAC1 with EP300. While PARP1 was dispensable for HDAC1 dissociation, EP300 was found only at gene promoters enriched in PARP1. EP300 activated transcription of PARP1/RBL2 co-regulated genes, but not genes solely controlled by RBL2. DNA was a prerequisite to the formation of an immunoprecipitated PARP1-EP300 complex, suggesting that PARP1 enabled EP300 binding, which in turn activated gene transcription. Notably, PARP1 overexpression failed to overcome the inhibitory effect of RBL2 on MAP2K6 and MAPK3 transcription. The same interdependence was observed in proliferating cancer cells; the low abundance of RBL2 resulted in PARP1-mediated EP300 recruitment to promoters of the MAP2K6 and MAPK3 genes. We conclude that RBL2 may indirectly regulate transcription of some genes by controlling PARP1-mediated EP300 recruitment.
人类单核细胞的分化与增殖停滞相关，这是由基因阻遏物视网膜母细胞瘤蛋白家族（尤其是该家族）的激活所导致的，这些蛋白以E2F依赖的方式靶向基因启动子。为了研究RBL2在定义单核细胞表型和功能中的作用，我们使用了引物文库。我们鉴定出了编码两种表面受体（CXCR1和IL17RE）以及两种TLR信号介质（CD86和NFKB2）的基因，它们被RBL2 - E2F4 - HDAC1 - BRM复合物所抑制。令人惊讶的是，PARP1共同调节了RBL2控制的28个已鉴定基因中的24个。在RBL2沉默后，PARP1被招募到RBL2依赖基因的一个子集，以MAP2K6和MAPK3为代表。RBL2沉默还恢复了PARP1的转录。富含PARP1的基因启动子的特征是组蛋白乙酰化增加，并且HDAC1被EP300取代。虽然PARP1对于HDAC1的解离是可有可无的，但仅在富含PARP1的基因启动子处发现了EP300。EP300激活了PARP1 / RBL2共同调节基因的转录，但不激活仅由RBL2控制的基因的转录。DNA是免疫沉淀的PARP1 - EP300复合物形成的先决条件，这表明PARP1使EP300能够结合，进而激活基因转录。值得注意的是，PARP1的过表达未能克服RBL2对MAP2K6和MAPK3转录的抑制作用。在增殖的癌细胞中也观察到了相同的相互依赖性；RBL2的低丰度导致PARP1介导的EP300被招募到MAP2K6和MAPK3基因的启动子上。我们得出结论，RBL2可能通过控制PARP1介导的EP300招募来间接调节某些基因的转录。
