Feola, Maria, Zamperone, Andrea, Moskop, Daniel, Chen, Huiyong, Casu, Carla, Lama, Dechen, Di Martino, Julie, Djedaini, Mansour, Papa, Luena, Martinez, Marc Ruiz, Choesang, Tenzin, Bravo-Cordero, Jose Javier, MacKay, Matthew, Zumbo, Paul, Brinkman, Nathan, Abrams, Charles S., Rivella, Stefano, Hattangadi, Shilpa, Mason, Christopher E., and Hoffman, Ronald
Erythropoiesis involves complex interrelated molecular signals influencing cell survival, differentiation, and enucleation. Diseases associated with ineffective erythropoiesis, such as β-thalassemias, exhibit erythroid expansion and defective enucleation. Clear mechanistic determinants of what make erythropoiesis effective are lacking. We previously demonstrated that exogenous transferrin ameliorates ineffective erythropoiesis in β-thalassemic mice. In the current work, we utilize transferrin treatment to elucidate a molecular signature of ineffective erythropoiesis in β-thalassemia. We hypothesize that compensatory mechanisms are required in β-thalassemic erythropoiesis to prevent apoptosis and enhance enucleation. We identify pleckstrin-2—a STAT5-dependent lipid binding protein downstream of erythropoietin—as an important regulatory node. We demonstrate that partial loss of pleckstrin-2 leads to worsening ineffective erythropoiesis and pleckstrin-2 knockout leads to embryonic lethality in β-thalassemic mice. In addition, the membrane-associated active form of pleckstrin-2 occurs at an earlier stage during β-thalassemic erythropoiesis. Furthermore, membrane-associated activated pleckstrin-2 decreases cofilin mitochondrial localization in β-thalassemic erythroblasts and pleckstrin-2 knockdown in vitro induces cofilin-mediated apoptosis in β-thalassemic erythroblasts. Lastly, pleckstrin-2 enhances enucleation by interacting with and activating RacGTPases in β-thalassemic erythroblasts. This data elucidates the important compensatory role of pleckstrin-2 in β-thalassemia and provides support for the development of targeted therapeutics in diseases of ineffective erythropoiesis. Maria Feola et al., elucidate the compensatory role of pleckstrin-2 in ineffective erythropoiesis in β-thalassemic mice by reducing cofilin-mediated apoptosis and enhancing enucleation by activating RacGTPases. These findings could support future therapeutic interventions. [ABSTRACT FROM AUTHOR]