ZFP148 (ZBP-89)/ZFP281 (ZBP-99) family transcription factors are required for normal erythroid differentiation

A complete understanding of hematopoietic transcriptional control requires the identification of all relevant trans and cis-acting factors. We previously identified the Kruppel-type zinc finger transcription factor zfp148 (also called ZBP-89) as a novel GATA1 interacting partner through a non-biased proteomic screen (Woo et al. 2008, Mol. Cell Bio 28:2675-2689). Moreover, we showed that GATA1 and Zfp148 occupy many common chromatin sites in erythroid cells and that Zfp148 recruits p300 and GCN5/Trapp histone acetyltransferases to these regions (Woo et al. 2011. Blood 118:3684-3693). In vitro and tetraploid complementation assays using a zfp148 genetrap allele showed that zfp148 deficiency causes partial erythroid maturation defects. We have now generated a conditional zfp148 knock out mouse model. Global zfp148 loss results in perinatal lethality due to non-hematologic causes. Selective zfp148 loss within the hematopoietic system using either Vav-Cre or Mx1-Cre results in a mild hypochromic anemia, mildly impaired erythroid maturation, and delayed recovery from phenylhydrazine-induced hemolysis in older mice. zfp281 (also called ZBP-99) is the only other known zfp148 gene family member. It markedly increases in expression during erythroid cell commitment/maturation and physically associates with GATA1, similar to zfp148. To examine potential functional redundancy between zfp281 and zp148, lentiviral shRNA knock down of zfp281 was performed on zfp148 knock out versus wild type murine fetal liver cells. Whereas deficiency of zfp148 and zfp281 separately led to modestly impaired erythroid maturation, double deficiency caused a marked defect in erythroid maturation, primarily at the CD71+Ter119- to CD71+Ter119 stage. Lastly, GATA1 chromatin occupancy sites of activated GATA1 direct target genes were found to be strongly enriched for Zfp148/281 DNA binding consensus motifs compared to repressed direct target genes. Collectively, these findings uncover a previously unknown role for zfp281 in erythroid cell differentiation and demonstrate functional redundancy with its family member zfp148. They also suggest that zfp148/281 family transcription factors act to recruit activating chromatin remodeling complexes to positively regulate GATA1 direct target genes.