mTORC1 activity is essential for erythropoiesis and B cell lineage commitment

Malik, N. , Dunn, K. M., Cassels, J., Hay, J. , Estell, C., Sansom, O. J. and Michie, A. M. (2019) mTORC1 activity is essential for erythropoiesis and B cell lineage commitment. Scientific Reports, 9, 16917. (doi: 10.1038/s41598-019-53141-1) (PMID:31729420) (PMCID:PMC6858379)

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Mechanistic target of rapamycin (mTOR) is a serine/threonine protein kinase that mediates phosphoinositide-3-kinase (PI3K)/AKT signalling. This pathway is involved in a plethora of cellular functions including protein and lipid synthesis, cell migration, cell proliferation and apoptosis. In this study, we proposed to delineate the role of mTORC1 in haemopoietic lineage commitment using knock out (KO) mouse and cell line models. Mx1-cre and Vav-cre expression systems were used to specifically target Raptorfl/fl (mTORC1), either in all tissues upon poly(I:C) inoculation, or specifically in haemopoietic stem cells, respectively. Assessment of the role of mTORC1 during the early stages of development in Vav-cre+Raptorfl/fl mice, revealed that these mice do not survive post birth due to aberrations in erythropoiesis resulting from an arrest in development at the megakaryocyte-erythrocyte progenitor stage. Furthermore, Raptor-deficient mice exhibited a block in B cell lineage commitment. The essential role of Raptor (mTORC1) in erythrocyte and B lineage commitment was confirmed in adult Mx1-cre+Raptorfl/fl mice upon cre-recombinase induction. These studies were supported by results showing that the expression of key lineage commitment regulators, GATA1, GATA2 and PAX5 were dysregulated in the absence of mTORC1-mediated signals. The regulatory role of mTOR during erythropoiesis was confirmed in vitro by demonstrating a reduction of K562 cell differentiation towards RBCs in the presence of established mTOR inhibitors. While mTORC1 plays a fundamental role in promoting RBC development, we showed that mTORC2 has an opposing role, as Rictor-deficient progenitor cells exhibited an elevation in RBC colony formation ex vivo. Collectively, our data demonstrate a critical role played by mTORC1 in regulating the haemopoietic cell lineage commitment.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Michie, Professor Alison and Dunn, Mrs Karen and Estell, Mr Christopher and Malik, Miss Natasha and Hay, Dr Jodie and Sansom, Professor Owen and Cassels, Miss Jennifer
Authors: Malik, N., Dunn, K. M., Cassels, J., Hay, J., Estell, C., Sansom, O. J., and Michie, A. M.
College/School:College of Medical Veterinary and Life Sciences > School of Cancer Sciences
College of Medical Veterinary and Life Sciences > School of Infection & Immunity
Journal Name:Scientific Reports
Publisher:Nature Research
ISSN (Online):2045-2322
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Scientific Reports 9:16917
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
172449Elucidating the role of individual mTor complexes in the development and progression of chronic lymphocytic leukaemiaAlison MichieBloodwise (BLOODWIS)15041CS - Paul O'Gorman Leukaemia Research Centre
163632Development of a flow cytometry service within the Paul O'Gorman Leukaemia Research CentreAlison MichieThe Kay Kendall Leukaemia Fund (KENDALL)KKL501CS - Paul O'Gorman Leukaemia Research Centre
190660MRC Doctoral Training Grant 2013/14 and 2014/15George BaillieMedical Research Council (MRC)MR/K501335/1MVLS - Graduate School