Biogenesis of the red blood cell membrane
In the bone marrow, red blood cells (RBC) are constantly being produced from hematopoietic stem cells (also called progenitor cells), a process called erythropoiesis. The peripheral blood of an individual also contains a host of progenitor cells that can be induced to undergo erythropoiesis. We are developing culture techniques to maximize the production of red blood cells from peripheral blood for the study of erythropoiesis and the eventual manufacture of red blood cells for diagnostics or transfusion.
During the process of erythropoiesis, red blood cell progenitors undergo a remarkable transformation; they become smaller, express a variety of erythroid specific proteins (e.g. Haemoglobin and band 3 (AE1)), lose their nucleus and remodel their membrane to generate the nascent reticulocyte and then mature further to the recognizable biconcave red blood cell. Whilst undergoing these substantial morphological changes the progenitor cell must assemble and selectively retain key membrane protein complexes (e.g. band 3 (AE1) and Rhesus proteins). These membrane protein complexes give the RBC membrane its unique antigenic and structural properties and facilitate efficient gas exchange. Very little is known about how multiprotein complexes are assembled or correctly localized during erythropoiesis or why specific alterations in membrane protein composition occur in red cell diseases such as Hereditary Spherocytosis.
We are using biochemical and cell biology techniques to monitor the expression and interactions of erythroid specific proteins throughout differentiation in health and disease. We are also manipulating RBC progenitor protein expression using siRNA/shRNA technology or by introducing mutant proteins into the cells. This work will greatly enhance our knowledge of the structure-function relationships within the RBC membrane and will identify the stages and mechanisms whereby membrane protein composition is altered during normal differentiation process and during human disease.
Our studies will facilitate the production of "designer" red cells from donated blood for diagnostic use and are vital for confirming the viability of blood cells produced using embryonic stem cells or human induced pluripotent stem cells (hiPSC). They also are important for understanding specific structure-function properties of the red blood cell are achieved and also improve our understanding of the role of related proteins in other cells types.
May Grünwald/Giemsa cytospins showing the different cell stages during human erythropoiesis: from the proerythroblast to the enucleated reticulocyte. The confocal imaging shows band 3 localisation. Images taken from Satchwell et al 2011 Blood 118; 182-191
Alex Gampel, Tim Satchwell, Beth Hawley, Steph Pellegrin, Charlotte Severn, Mandy Bell and Kat Mordue.
Bell AJ, Satchwell TJ, Heesom KJ, Hawley BR, Kupzig S, Hazell M, Mushens R, Herman A, Toye AM. (2013) Protein distribution during human erythroblast enucleation in vitro. PLOS ONE. 8(4): e60300.
Pellegrin S, Heesom KJ, Satchwell TJ, Hawley BR, Daniels G, van den Akker E, Toye AM. (2012) Differential proteomic analysis of human erythroblasts undergoing apoptosis induced by epo-withdrawal. PLOS ONE. 7(6): e38356.
Anstee DJ, Gampel A, Toye AM. (2012). Ex vivo generation of human red cells for transfusion. Current Opinion in Hematology. 19: 163-169.
Satchwell TJ, Bell AJ, Pellegrin S, Kupzig S, Ridgwell K, Daniels G, Anstee DJ, van den Akker E, Toye AM. (2011). Critical band 3 multiprotein complex interactions establish early during human erythropoiesis. Blood. 118: 182-191.