Epigenetic Determinants of Erythropoiesis: Role of the Histone Methyltransferase SetD8 in Promoting Erythroid Cell Maturation and Survival

Abstract

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.

This article is related to:

Histone Methyltransferase Setd8 Represses Gata2 Expression and Regulates Erythroid Maturation

Histone Methyltransferase Setd8 Represses Gata2 Expression and Regulates Erythroid Maturation

ACKNOWLEDGMENTS

This work was supported by NIH grant DK50107 (to E.H.B.) and Cancer Center Support Grant P30 CA014520. A.W.D. was supported by a Cancer Biology Predoctoral NIH Training Grant from the National Institutes of Health (T32CA009135) and an American Heart Association Predoctoral Fellowship.

We thank Kirby Johnson and Xin Gao for providing critical comments and Mitchell Weiss for providing MSCV-PIG vector. We thank Lixin Rui for providing active caspase-3 and cleaved PARP antibodies.