Lee PY, Sykes DB, Ameri S, Kalaitzidis D, Charles JF, Nelson-Maney N, Wei K, Cunin P, Morris A, Cardona AE, Root DE, Scadden DT, Nigrovic PA. 2017. The metabolic regulator mTORC1 controls terminal myeloid differentiation. Science immunology. 2(11). Pubmed: 28763796 DOI:10.1126/sciimmunol.aam6641


Monocytes are derived from hematopoietic stem cells through a series of intermediate progenitor stages, but the factors that regulate this process are incompletely defined. Using a Ccr2/Cxcr1 dual-reporter system to model murine monocyte ontogeny, we conducted a small-molecule screen that identified an essential role of mechanistic target of rapamycin complex 1 (mTORC1) in the development of monocytes and other myeloid cells. Confirmatory studies using mice with inducible deletion of the mTORC1 component Raptor demonstrated absence of mature circulating monocytes, as well as disruption in neutrophil and dendritic cell development, reflecting arrest of terminal differentiation at the granulocyte-monocyte progenitor stage. Conversely, excess activation of mTORC1 through deletion of the mTORC1 inhibitor tuberous sclerosis complex 2 promoted spontaneous myeloid cell development and maturation. Inhibitor studies and stage-specific expression profiling identified failure to down-regulate the transcription factor Myc by the mTORC1 target ribosomal S6 kinase 1 (S6K1) as the mechanistic basis for disrupted myelopoiesis. Together, these findings define the mTORC1-S6K1-Myc pathway as a key checkpoint in terminal myeloid development.
Copyright © 2017, American Association for the Advancement of Science.

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David Scadden’s laboratory is dedicated to discovering the principles governing blood cell production, with the ultimate goal of guiding the development of therapies for blood disorders and cancer.

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