Regulation of Gene Expression During Erythropoiesis
The molecular events that confer the ability to express lineage-specific genes upon an initially uncommitted, pluripotent hematopoietic stem cell remain a major question in cell differentiation. Use of an immortalized erythroid cell line as a means to isolate genes that may be important for erythroid function allowed us to identify a novel, erythroid-specific gene, which was named EKLF (erythroid Krüppel-like factor).
Biochemical, molecular, cellular, developmental, and genetic studies in mice and humans have established that EKLF is an essential component required for globin switching and completion of the definitive erythroid program. Disorders of hemoglobin expression can lead to a variety of hemoglobinopathies, including sickle cell anemia and ß–thalassemia (Cooley’s anemia). As a result, our examination of EKLF’s mechanism of action has illuminated how it regulates the globin locus, and has provided us with a way to reconstruct EKLF so that it can potentially rectify one type of hemoglobin disorder.
Our discovery of EKLF has stimulated other investigators around the world to search for analogous genes that can work in a similar fashion to regulate unique targets in other tissues. EKLF is now the founding member (KLF1) of a family of seventeen proteins, some of which have been directly implicated in suppression of a specific subset of cancers.
Mount Sinai, Ph.D.
Department of Cell, Developmental, & Regenerative Biology
Black Family Stem Cell Institute
Tisch Cancer Institute
Mindich Child Health and Development Institute
We are vigorously continuing the study of EKLF (KLF1) using a number of approaches, including biochemical and structure/function analyses of the EKLF protein, identification of its protein partners, examining its ability to extrinsically control erythropoiesis, and monitoring how EKLF expression itself is so precisely regulated during development.
Our most recent studies are focused on a number of areas: one, a continuing analysis of EKLF protein/protein interactions and how they result in altered transcriptional and epigenetic changes at target loci; two, on how these controls converge to regulate late events in erythropoiesis, particularly enucleation; three, on analysis of EKLF upstream regulators to help explain its exquisite tissue-restricted expression pattern, and to possibly link alteration of its expression level to aberrant red cell biology; four, on functional and phenotypic analyses of a neonatal anemia mouse mutant (Nan) that contains a mutation in one allele of EKLF; finally, on determining the mechanism by which a human mutation in EKLF leads to congenital dyserythropoietic anemia.
Sample Recent Publications
Varricchio, A. Planutis, D. Manwani, J. Jaffray, W.B. Mitchell, A.R. Migliaccio, Genetic disarray follows mutant KLF1-E325K expression in a congenital dyserythropoietic anemia patient, Haematologica, in press (2019). [highlighted in Hematopoiesis News]
M.N. Gnanapragasam, J.D. Crispino, A.M. Ali, R. Weinberg, R. Hoffman, A. Raza, Survey and evaluation of mutations in the human KLF1 transcription unit, Scientific Reports, 8, 6587 (2018).
Planutis, L. Xue, C.D. Trainor, M. Dangeti, K. Gillinder, M. Siatecka, L.L. Peters, A.C. Perkins, Neomorphic effects of the neonatal anemia (Nan-EKLF) mutation contribute to deficits throughout development, Development, 144, 430-440 (2017). [highlighted as an In this Issue preview; highlighted in Hematopoiesis News]
M.N. Gnanapragasam, K.E. McGrath, S. Catherman, L. Xue, J. Palis, EKLF/KLF1-regulated cell cycle exit is essential for erythroblast enucleation, Blood, 128, 1631-1641 (2016). [highlighted in Hematopoiesis News]
Lohmann*, M. Dangeti*, S. Soni, X. Chen, A. Planutis, M.H. Baron, K. Choi The DEK oncoprotein is a critical component of the EKLF/KLF1 enhancer in erythroid cells, Molecular and Cellular Biology, 35, 3726-3738 (2015). [*co-first authors] [highlighted in Exp Hem 43, 827 (15)]
Soni , N. Pchelintsev , P.D. Adams Transcription factor EKLF (KLF1) recruitment of the histone chaperone HIRA is essential for ß-globin gene expression, Proceedings of the National Academy of Sciences, 111, 13337-13342 (2014). [highlighted in Hematopoiesis News]
M.N. Gnanapragasam Orchestration of late events in erythropoiesis by KLF1/EKLF, Current Opinion in Hematology, 24, 183-190 (2017).
Perkins, X. Xu, D.R. Higgs, G.P. Patrinos, L. Arnaud and S. Philipsen, “Krüppeling” erythropoiesis: an unexpected broad spectrum of human red blood cell disorders due to KLF1 variants, Blood, 127, 1856-1862 (2016).
Manwani KLF1: when less is more, Blood, 124, 672-673 (2014).
Yien EKLF/KLF1: a tissue-restricted integrator of transcriptional control, chromatin remodeling, and lineage determination, Molecular and Cellular Biology, 33, 4-13 (2013).
Siatecka The multifunctional role of EKLF/KLF1 during erythropoiesis, Blood, 118, 2044-2054 (2011).
Putting a finger on the switch, Nature Genetics, 42, 733-734 (2010).
Krüppel-like Factors: Three Fingers in Many Pies, Journal of Biological Chemistry, 276, 34355-34358 (2001).