GATA-1-Mediated Proliferation Arrest during Erythroid Maturation

Abstract

Transcription factor GATA-1 is essential for erythroid and megakaryocytic maturation. GATA-1 mutations are associated with hematopoietic precursor proliferation and leukemogenesis, suggesting a role in cell cycle control. While numerous GATA-1 target genes specifying mature hematopoietic phenotypes have been identified, how GATA-1 regulates proliferation remains unknown. We used a complementation assay based on synchronous inducible rescue of GATA-1 ؊ erythroblasts to show that GATA-1 promotes both erythroid maturation and G 1 cell cycle arrest. Molecular studies combined with microarray transcriptome analysis revealed an extensive GATA-1-regulated program of cell cycle control in which numerous growth inhibitors were upregulated and mitogenic genes were repressed. GATA-1 inhibited expression of cyclin-dependent kinase (Cdk) 6 and cyclin D2 and induced the Cdk inhibitors p18INK4C and p27 Kip1 with associated inactivation of all G 1 Cdks. These effects were dependent on GATA-1-mediated repression of the c-myc (Myc) proto-oncogene. GATA-1 inhibited Myc expression within 3 h, and chromatin immunoprecipitation studies indicated that GATA-1 occupies the Myc promoter in vivo, suggesting a direct mechanism for gene repression. Surprisingly, enforced expression of Myc prevented GATA-1-induced cell cycle arrest but had minimal effects on erythroid maturation. Our results illustrate how GATA-1, a lineage-determining transcription factor, coordinates proliferation arrest with cellular maturation through distinct, interrelated genetic programs.

CDC6 expression is regulated by lineage-specific transcription factor GATA1

“…The results reported here are in line with other reports that suggest that GATA1 is a direct cell cycle regulator, 15,21 but GATA1 is primarily defined as a paradigmatic lineage-instructive regulator required for proper homeostasis of erythrocytes and megakaryocytes. In fact, transcriptional control of most of these lineages genes has been shown to depend on GATA1 activity.…”

“…Another example is GATA1-induced megakaryocytic endoreplication, the entrance into a special cell cycle that needs maintenance of CDC6 and other cell cycle regulators expression in the absence of proliferation. 10,35 We suggest that regulated CDC6 expression during cell differentiation, as documented in muscle, 38 erythroid and megakaryocytic lineages 10,15,32 and prostate cancer cells 43 is the outcome of the coordinated action of E2F proteins linked to mitotic cell cycles and of tissue-specific transcription factors such as MyoD, GATA1 or androgen receptor.…”

“…This CP2 complex was also supershifted in the presence of anti-CP2 by entrance into endoreplication cycles, and final erythroid differentiation needs GATA1-mediated proliferation arrest. 41 Also, GATA1 inhibits cell proliferation through control of many genes involved in cell cycle regulation, as revealed by microarray expression analysis 15 and, more significantly, by ChIP-seq approach. 21,22 Among the identified putative cell cycle targets, E2f4 and Nek6, together with CDC6 are under direct control of GATA1.…”

“…Initially identified as a protein that binds cis-regulatory elements of the β-globin gene, it has since been shown to regulate a vast number of specific erythro-megakaryocytic genes 13,14 or hematopoietic proto-oncogenes, such as c-MYC and c-MYB. 15,16 underlining the potential dominant-negative effect of GATA1s. GATA1-dependent increase in CDC6 expression could also be seen at the protein level (Fig.…”

“…In fact, transcriptional control of most of these lineages genes has been shown to depend on GATA1 activity. 15,21,22,39,40 However, final differentiation and maturation of these cells is accompanied by changes in cell proliferation and therefore in cell cycle status: megakaryocytic maturation is characterized Mutagenesis Kit (Stratagene). The DNA sequence of all mutant and/or tag-fused cDNAs were verified accordingly.…”