Identification of Putative Direct Target Genes of IKZF1 (Ikaros) in Erythropoiesis — ASN Events

Identification of Putative Direct Target Genes of IKZF1 (Ikaros) in Erythropoiesis (#230)

Kiran Asplett 1 , Graham Magor 1 , Kevin Gillinder 1 , Peter Papathanasiou 2 , Stephen Huang 1 , Andrew Perkins 1
  1. University of Queensland, Woolloongabba, QLD, Australia
  2. John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia

IKZF1 (Ikaros) is a C2H2 zinc finger transcription factor encoded by the gene, Ikzf1. An ENU mutagenesis screen in mice uncovered a point mutation within Ikzf1, the Plastic mutation, which stops the ability of protein to interact with DNA. Mice heterozygous for the Plastic mutation develop lymphoblastic leukaemia, whereas homozygous mice die in utero from anaemia. The role of IKZF1 in a lymphoid context has been the target of extensive research as it is relevant to the understanding of B-cell acute lymphoblastic leukaemia and acute myeloid leukaemia. However the role of IKZF1 in an erythroid context is poorly understood.

Understanding the biochemical functions of IKZF1 in an erythroid context is critical as the Plastic mutation was found to cause dysregulation of haemoglobin switching; the developmental switch from foetal to adult haemoglobin. This gradual switch starts at birth and causes the transcription of diseased β-globin within β-haemoglobinopathies. Haemoglobin switching has been heavily researched as understanding the mechanism of the switch could hold the key to developing targeted cures for patients suffering diseases such as sickle cell disease.

To analyse the role of IKZF1 in an erythroid context I examined perturbations in the transcriptome of Plastic mice foetal liver, using RNA-seq, to derive a list of IKZF1 dependant genes. This list included key tumour suppressor, lymphoid and erythroid specific genes. The DNA binding activity of IKZF1 was also analysed in the first erythroid ChIP-seq. The ChIP-seq data rediscovered previously identified IKZF1 binding sites from lymphoid ChIP-seq data as well as produced a unique set of novel erythroid specific binding sites. The IKZF1 ChIP-seq generated evidence of a potential novel interaction between IKZF1 and EGR1 as well as IKZF1 and KLF1. A set of putative IKZF1 direct target genes were produced by determining which IKZF1 dependant genes contained an adjacent IKZF1 binding site. This set included key erythroid genes such EpoR, Trfr2 and Icam4.

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