DeVilbiss Andrew W, Sanalkumar Rajendran, Hall Bryan D R, Katsumura Koichi R, de Andrade Isabela Fraga, Bresnick Emery H
Department of Cell and Regenerative Biology, UW-Madison Blood Research Program, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
Department of Cell and Regenerative Biology, UW-Madison Blood Research Program, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
Mol Cell Biol. 2015 Jun;35(12):2073-87. doi: 10.1128/MCB.01422-14. Epub 2015 Apr 8.
Erythropoiesis, in which committed progenitor cells generate millions of erythrocytes daily, involves dramatic changes in the chromatin structure and transcriptome of erythroblasts, prior to their enucleation. While the involvement of the master-regulatory transcription factors GATA binding protein 1 (GATA-1) and GATA-2 in this process is established, the mechanistic contributions of many chromatin-modifying/remodeling enzymes in red cell biology remain enigmatic. We demonstrated that SetD8, a histone methyltransferase that catalyzes monomethylation of histone H4 at lysine 20 (H4K20me1), is a context-dependent GATA-1 corepressor in erythroid cells. To determine whether SetD8 controls erythroid maturation and/or function, we used a small hairpin RNA (shRNA)-based loss-of-function strategy in a primary murine erythroblast culture system. In this system, SetD8 promoted erythroblast maturation and survival, and this did not involve upregulation of the established regulator of erythroblast survival Bcl-x(L). SetD8 catalyzed H4K20me1 at a critical Gata2 cis element and restricted occupancy by an enhancer of Gata2 transcription, Scl/TAL1, thereby repressing Gata2 transcription. Elevating GATA-2 levels in erythroid precursors yielded a maturation block comparable to that induced by SetD8 downregulation. As lowering GATA-2 expression in the context of SetD8 knockdown did not rescue erythroid maturation, we propose that SetD8 regulation of erythroid maturation involves multiple target genes. These results establish SetD8 as a determinant of erythroid cell maturation and provide a framework for understanding how a broadly expressed histone-modifying enzyme mediates cell-type-specific GATA factor function.
红细胞生成过程中，定向祖细胞每天可产生数百万个红细胞，在此过程中，成红细胞在去核之前，其染色质结构和转录组会发生显著变化。虽然主要调控转录因子GATA结合蛋白1（GATA-1）和GATA-2在此过程中的作用已得到证实，但许多染色质修饰/重塑酶在红细胞生物学中的机制贡献仍不清楚。我们证明，SetD8是一种组蛋白甲基转移酶，可催化组蛋白H4赖氨酸20位点的单甲基化（H4K20me1），在红细胞中是一种依赖于上下文的GATA-1共抑制因子。为了确定SetD8是否控制红细胞成熟和/或功能，我们在原代小鼠成红细胞培养系统中使用了基于小发夹RNA（shRNA）的功能丧失策略。在该系统中，SetD8促进成红细胞成熟和存活，且这一过程不涉及成红细胞存活的既定调节因子Bcl-x(L)的上调。SetD8在关键的Gata2顺式元件处催化H4K20me1，并限制Gata2转录增强子Scl/TAL1的占据，从而抑制Gata2转录。提高红细胞前体中GATA-2的水平会导致类似于SetD8下调所诱导的成熟阻滞。由于在SetD8敲低的情况下降低GATA-2表达并不能挽救红细胞成熟，我们提出SetD8对红细胞成熟的调节涉及多个靶基因。这些结果确立了SetD8作为红细胞成熟的决定因素，并为理解一种广泛表达的组蛋白修饰酶如何介导细胞类型特异性GATA因子功能提供了框架。
