EKLF/KLF1 Controls Cell Cycle Entry via Direct Regulation of E2f2

• Published in: The Journal of biological chemistry 2009-07, Vol.284 (31), p.20966-20974
• Main Authors: Tallack, Michael R., Keys, Janelle R., Humbert, Patrick O., Perkins, Andrew C.
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Binding Sites; Cell Cycle; Conserved Sequence; E2F2 Transcription Factor - genetics; E2F2 Transcription Factor - metabolism; E2F4 Transcription Factor - genetics; E2F4 Transcription Factor - metabolism; Enhancer Elements, Genetic - genetics; Erythroid Cells - cytology; Erythroid Cells - metabolism; Erythropoiesis; Gene Deletion; Gene Expression Regulation; Introns - genetics; Kruppel-Like Transcription Factors - deficiency; Kruppel-Like Transcription Factors - metabolism; Mice; Molecular Sequence Data; Retinoblastoma Protein - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; S Phase; Transcription Factors - metabolism; Transcription, Chromatin, and Epigenetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M109.006346

Differentiation of erythroid cells requires precise control over the cell cycle to regulate the balance between cell proliferation and differentiation. The zinc finger transcription factor, erythroid Krüppel-like factor (EKLF/KLF1), is essential for proper erythroid cell differentiation and regulates many erythroid genes. Here we show that loss of EKLF leads to aberrant entry into S-phase of the cell cycle during both primitive and definitive erythropoiesis. This cell cycle defect was associated with a significant reduction in the expression levels of E2f2 and E2f4, key factors necessary for the induction of S-phase gene expression and erythropoiesis. We found and validated novel intronic enhancers in both the E2f2 and E2f4 genes, which contain conserved CACC, GATA, and E-BOX elements. The E2f2 enhancer was occupied by EKLF in vivo. Furthermore, we were able to partially restore cell cycle dynamics in EKLF−/− fetal liver upon additional genetic depletion of Rb, establishing a genetic causal link between reduced E2f2 and the EKLF cell cycle defect. Finally, we propose direct regulation of the E2f2 enhancer is a generic mechanism by which many KLFs regulate proliferation and differentiation.