Elucidating mechanisms that regulate erythroid cell maturation is critical for devising targeted therapies for red cell disorders including thalassemias, polycythemia vera and anemias, and for developing strategies to generate red blood cells for clinical transfusion. The PI3-kinase-AKT pathway promotes and suppresses erythroid maturation. The inhibitory mechanism involves AKT-mediated phosphorylation of FoxO3, which leads to its sequestration in the cytoplasm. FoxO3 is upregulated/activated during erythroid maturation and by oxidative stress and controls the erythroid cell cycle and maturation, red blood cell lifespan, and protects against oxidative stress. We developed evidence that the serine/threonine kinase mTOR engages in crosstalk with FoxO3 to control erythroid maturation. Mechanisms underlying FoxO3- mTOR crosstalk in any context are poorly understood. FoxO3 and mTOR were known to have critical independent functions to control autophagy in non-erythroid cells. Autophagy mediates the consumption of damaged cellular components and differentiation-associated cellular remodeling, including mitochondria disposal as a key step in erythrocyte development. We discovered that FoxO3 facilitates GATA-1-instigated autophagy gene activation and accumulation of the autophagosome during erythroid maturation. GATA-1 also activates autophagy by directly inducing FoxO3 expression. We hypothesize that GATA-1-FoxO3 cooperativity controls autophagy and is modulated by mTOR signaling, which would constitute a new paradigm with considerable potential for therapeutic modulation of erythropoiesis and understanding erythroid pathophysiologies. The Bresnick and Ghaffari groups will collectively test this hypothesis and elucidate mechanisms.
Aim 1 - To elucidate mechanisms underlying FoxO3 regulation of terminal erythroid maturation. We will test the hypothesis that FoxO3 has a critical function to promote autophagy in late erythroid maturation. We will determine whether FoxO3 stimulates autophagy in steady-state and stress erythropoiesis contexts, if oxidative stress influences erythroid maturation by controlling autophagy, and if mTOR-FoxO3 crosstalk regulates autophagy. As inhibition of mTOR signaling improves anemia in a b-thalassemia model, we will address the potential function of autophagy in b-thalassemia.
Aim 2 - To discriminate among models to explain how GATA-1 and FoxO3 cooperatively control autophagy and erythroid maturation. We hypothesize that GATA-1-FoxO3 cooperativity represents a physiological mechanism to control erythroid maturation. We will distinguish between models to understand the cooperativity, which conforms to a type I coherent feed-forward loop, and will determine how it contributes to establishment/maintenance of the erythroid genetic network. Given the importance of GATA and FoxO factors for regulating diverse processes, the studies will yield broad mechanistic and biological insights.

Public Health Relevance

Elucidating mechanisms that regulate erythroid cell differentiation/maturation is critical for devising targeted therapies for disorders including thalassemias, polycythemia vera and anemias, and for developing strategies to generate red blood cels ex vivo for clinical transfusion. Based on new discoveries from the Bresnick and Ghaffari groups, we present evidence for a new paradigm of controling erythroid cel maturation with considerable potential for therapeutic modulation of erythropoiesis and understanding erythroid pathophysiologies. We shal elucidate the underlying mechanisms, and we anticipate that the studies will also yield broad mechanistic and biological insights.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL116365-01
Application #
8417051
Study Section
Special Emphasis Panel (ZHL1-CSR-O (S1))
Program Officer
Hanspal, Manjit
Project Start
2012-09-26
Project End
2016-06-30
Budget Start
2012-09-26
Budget End
2013-06-30
Support Year
1
Fiscal Year
2012
Total Cost
$411,817
Indirect Cost
$74,942
Name
University of Wisconsin Madison
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Bigarella, Carolina L; Li, Jianfeng; Rimmelé, Pauline et al. (2017) FOXO3 Transcription Factor Is Essential for Protecting Hematopoietic Stem and Progenitor Cells from Oxidative DNA Damage. J Biol Chem 292:3005-3015
Liang, Raymond; Ghaffari, Saghi (2017) Mitochondria and FOXO3 in stem cell homeostasis, a window into hematopoietic stem cell fate determination. J Bioenerg Biomembr 49:343-346
Katsumura, Koichi R; Bresnick, Emery H; GATA Factor Mechanisms Group (2017) The GATA factor revolution in hematology. Blood 129:2092-2102
Liang, Raymond; Ghaffari, Saghi (2016) Advances in understanding the mechanisms of erythropoiesis in homeostasis and disease. Br J Haematol 174:661-73
McIver, Skye C; Katsumura, Koichi R; Davids, Elsa et al. (2016) Exosome complex orchestrates developmental signaling to balance proliferation and differentiation during erythropoiesis. Elife 5:
Liang, Raymond; Rimmelé, Pauline; Bigarella, Carolina L et al. (2016) Evidence for AKT-independent regulation of FOXO1 and FOXO3 in haematopoietic stem and progenitor cells. Cell Cycle 15:861-7
Rimmelé, Pauline; Liang, Raymond; Bigarella, Carolina L et al. (2015) Mitochondrial metabolism in hematopoietic stem cells requires functional FOXO3. EMBO Rep 16:1164-76
Liang, Raymond; Campreciós, Genís; Kou, Yan et al. (2015) A Systems Approach Identifies Essential FOXO3 Functions at Key Steps of Terminal Erythropoiesis. PLoS Genet 11:e1005526
Rimmelé, Pauline; Lofek-Czubek, Sébastien; Ghaffari, Saghi (2014) Resveratrol increases the bone marrow hematopoietic stem and progenitor cell capacity. Am J Hematol 89:E235-8
Rimmelé, Pauline; Bigarella, Carolina L; Liang, Raymond et al. (2014) Aging-like phenotype and defective lineage specification in SIRT1-deleted hematopoietic stem and progenitor cells. Stem Cell Reports 3:44-59

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