Krüppel-like factor 2 regulated gene expression in mouse embryonic yolk sac erythroid cells.

KLF2 is a Krüppel-like zinc-finger transcription factor required for blood vessel, lung, T-cell and erythroid development. KLF2-/- mice die by embryonic day 14.5 (E14.5), due to hemorrhaging and heart failure. In KLF2-/- embryos, β-like globin gene expression is reduced, and E10.5 erythroid cells exhibit abnormal morphology. In this study, other genes regulated by KLF2 were identified by comparing E9.5 KLF2-/- and wild-type (WT) yolk sac erythroid precursor cells, using laser capture microdissection and microarray assays. One hundred and ninety-six genes exhibited significant differences in expression between KLF2-/- and WT; eighty-nine of these are downregulated in KLF2-/-. Genes involved in cell migration, differentiation and development are over-represented in the KLF2-regulated gene list. The SOX2 gene, encoding a pluripotency factor, is regulated by KLF2 in both ES and embryonic erythroid cells. Previous work had identified genes with erythroid-enriched expression in the yolk sac. The erythroid-enriched genes reelin, adenylate cyclase 7, cytotoxic T lymphocyte-associated protein 2 alpha, and CD24a antigen are downregulated in KLF2-/- compared to WT and are therefore candidates for controlling primitive erythropoiesis. Each of these genes contains a putative KLF2 binding site(s) in its promoter and/or an intron. Reelin has an established role in neuronal development. Luciferase reporter assays demonstrated that KLF2 directly transactivates the reelin promoter in erythroid cells, validating this approach to identify KLF2 target genes.