Poster abstracts

Poster number 181 submitted by Raja Sundari Meenakshi Sundaram

Defining the In Vivo role of the RNA-Binding Protein Pumilio1 in Erythropoiesis

Raja Sundari Meenakshi Sundaram (Center for Gene Regulation in Health and Disease GRHD, Cleveland State University), Anita R. Dhara, Rachael White (Center for Gene Regulation in Health and Disease GRHD, Department of Biological, Geological, and Environmental Sciences,Cleveland State University), Kenneth Peterson, Halyna Fedosyuk (Department of Biochemistry and Molecular Biology, University of Kansas Medical Center), Mahesh Ramamoorthy (Center for Gene Regulation in Health and Disease GRHD, Cleveland State University), Merlin Nithya Gnanapragasam (Center for Gene Regulation in Health and Disease GRHD, Department of Biological, Geological, and Environmental Sciences, Cleveland State University)

Abstract:
Pumilio1 (Pum1) is an RNA-binding protein involved in post-transcriptional regulation of gene expression. Our previous in vitro studies established Pum1 as a novel post-transcriptional repressor of human fetal hemoglobin (HbF). However, its physiological role in erythropoiesis in vivo remains unclear. Here, we investigated the dosage-dependent role of Pum1 during steady-state and stress erythropoiesis in Pum1 wild-type, heterozygous, and knockout mice. Under steady-state conditions, Pum1-deficient mice had largely normal hematological parameters but showed increased red cell distribution width (RDW) and changes in splenic erythroid populations. Following phenylhydrazine-induced hemolytic stress, Pum1-deficient mice showed an altered recovery response, with preliminary evidence of possible sex-associated differences. We next examined human globin transcripts in beta-YAC mice carrying the human gamma-globin locus. Heterozygous mice showed a trend toward increased fetal globin transcript levels, while adult globin transcripts were largely unchanged. To further examine this effect, we used the established erythroid model, Extensively Self-Renewing Erythroblasts (ESRE cells), derived from wild-type beta-YAC fetal liver. Enhancing Pum1 sequestration in these cells increased human fetal globin transcript levels without substantially affecting endogenous mouse globin expression. Together, these findings support a role for Pum1 in the response to erythropoietic stress and in post-transcriptional regulation of human fetal globin expression in vivo. Defining Pumilio-dependent post-transcriptional regulatory mechanisms will provide insight into HbF regulation and inform potential strategies for HbF induction in beta-hemoglobinopathies, including sickle cell disease and beta-thalassemia.

References:
1.Elagooz R, Dhara AR, Gott RM, Adams SE, White RA, Ghosh A, Ganguly S, Man Y, Owusu-Ansah A, Mian OY, Gurkan UA, Komar AA, Ramamoorthy M, Gnanapragasam MN. PUM1 mediates the posttranscriptional regulation of human fetal hemoglobin. Blood Adv. 2022 Dec 13;6(23):6016-6022. doi: 10.1182/bloodadvances.2021006730. PMID: 35667093; PMCID: PMC9699939.
2.Bennett LF, Liao C, Paulson RF. Stress Erythropoiesis Model Systems. Methods Mol Biol. 2018;1698:91-102. doi: 10.1007/978-1-4939-7428-3_5. PMID: 29076085; PMCID: PMC6510234.
3.Getman M, England SJ, Malik J, Peterson K, Palis J, Steiner LA. Extensively self-renewing erythroblasts derived from transgenic -yac mice is a novel model system for studying globin switching and erythroid maturation. Exp Hematol. 2014 Jul;42(7):536-46.e8. doi: 10.1016/j.exphem.2014.03.006. Epub 2014 Apr 2. PMID: 24704162; PMCID: PMC6176860.

Keywords: Pumilio1,gamma-globin, RNA-binding protein, beta-YAC mouse model, post-transcriptional regulation