To produce functional peripheral blood erythrocytes and platelets in correct amounts, the proliferation and maturation of the respective progenitors must be well balanced in response to environmental factors. The aim of the group is to understand the molecular processes that control the balance between proliferation and maturation during erythropoiesis and megakaryopoiesis. We use in vitro culture systems to expand progenitors and differentiate them to erythrocytes and megakaryocytes. In these cultures we investigate (i) how environmental factors control the execution of the internal genetic programming of the erythroid and megakaryocytic cells, and (ii) how inborn DNA mutations in patients with congenital anemia or thrombocytopenia cause these chronic diseases, and (iii) we establish protocols for large scale production of erythrocytes and platelets for transfusion purposes.

Role of mRNA translation in erythropoiesis 

SCF-induced activation of the PI3K-mTOR-eIF4E pathway results in selective translation of transcripts with a long 5´UTR. Iron availability and proteotoxicity induce eIF2 phosphorylation and translation start site selection. Ribosome diseases such as DBA and SBDS affect translation of distinct sets of transcripts. We investigate the mechanism by which specific transcripts are subject to selective translation, and which cellular processes are regulated at the level of selective mRNA translation.
Together with Dr Peter-Bram´t Hoen at the Department of Genetics (LUMC, Leiden) we established ribosome footprinting to investigate not only the efficiency of mRNA translation, but also translation of protein isoforms from transcripts harbouring short upstream open reading frames. 

Globin regulation and erythroid cell membrane stability.

In close cooperation with Dr. Sjaak Philipsen of the Dept. Cell Biology (ErasmusMC), and the Sickle Cell Disease Expertise Centers at the AMC and ErasmusMC, we make use of in vitro cultures of human erythroid progenitors from healthy individuals, thalassemia and sickle cell patients to study basic principles of erythroid differentiation. Factors that control the expression of gamma- versus beta-globin, may also affect the expression of erythroid membrane factors. 

Production of a personalized transfusion product 

To produce red cells for transfusion, we need an immortal source for rare blood group phenotypes. We are generating induced pluripotent stem cells (iPS) from buffycoats of donors with rare blood groups. We optimize erythropoiesis and megakaryopoiesis from these iPS for transfusion purposes. All research protocols will be transferred to GMP-compatible protocols in the Laboratory of Cell Therapy of Sanquin.

Megakaryopoiesis  

We employ the human iPSC model to investigate the molecular mechanisms of platelet generation that are affected by gene mutations that give rise to thrombocythopenia, or reduced platelet function. 

Key pulications

• Nahuel A. Paolini, Kat S. Moore, Franca M. di Summa, Ivo F.A.C. Fokkema, Peter A.C. ‘t Hoen, Marieke von Lindern (2018) Ribosome profiling uncovers selective mRNA translation associated with eIF2 phosphorylation in erythroid progenitors. PLoS One. 2018 Apr 10;13(4):e0193790.
• Moore KS, Yagci N, van Alphen F, Paolini NA, Horos R, Held NM, Houtkooper RH, van den Akker E, Meijer AB, 't Hoen PAC, von Lindern M. (2018) Csde1 binds transcripts involved in protein homeostasis and controls their expression in an erythroid cell line. Sci Rep. 2018 Feb 8;8(1):2628. 
• Heideveld E, Hampton-O'Neil LA, Cross SJ, van Alphen FPJ, van den Biggelaar M, Toye AM, van den Akker E. (2018) Glucocorticoids induce differentiation of monocytes towards macrophages that share functional and phenotypical aspects with erythroblastic island macrophages. Haematologica 2018 Mar;103(3):395-405. 
• Paolini NA, Attwood M, Sondalle SB, Vieira CM, van Adrichem AM, di Summa FM, O'Donohue MF, Gleizes PE, Rachuri S, Briggs JW, Fischer R, Ratcliffe PJ, Wlodarski MW, Houtkooper RH, von Lindern M, Kuijpers TW, Dinman JD, Baserga SJ, Cockman ME, MacInnes AW. A Ribosomopathy Reveals Decoding Defective Ribosomes Driving Human Dysmorphis. . Am J Hum Genet. 2017 Mar 2;100(3):506-522.
• Thiadens KA and von Lindern M. Selective mRNA translation in erythropoiesis. Biochem Soc Trans 2015; 43 (3): 343-7.