Single cell proteomics characterization of bone marrow hematopoiesis with distinct Ras pathway lesions

Normal hematopoiesis requires constant prolific production of different blood cell lineages by multipotent hematopoietic stem cells (HSC). Stem- and progenitor- cells need to balance dormancy with proliferation. How genetic alterations impact frequency, lineage potential, and metabolism of HSC is largely unknown. Here, we compared induced expression of KRASG12D or RasGRP1 to normal hematopoiesis. At low-resolution, both Ras pathway lesions result in skewing towards myeloid lineages. Single-cell resolution CyTOF proteomics unmasked an expansion of HSC- and progenitor- compartments for RasGRP1, contrasted by a depletion for KRASG12D. SCENITH™ quantitates protein synthesis with single-cell precision and corroborated that immature cells display low metabolic SCENITH™ rates. Both RasGRP1 and KRASG12D elevated mean SCENITH™ signals in immature cells. However, RasGRP1-overexpressing stem cells retain a metabolically quiescent cell-fraction, whereas this fraction diminishes for KRASG12D. Our temporal single cell proteomics and metabolomics datasets provide a resource of mechanistic insights into altered hematopoiesis at single cell resolution. ### Competing Interest Statement MHS is founder, shareholder and board member of Teiko.bio, has received a speaking honorarium from Fluidigm Inc., Kumquat Bio, and Arsenal Bio, has been a paid consultant for Five Prime, Ono, January, Earli, Astellas, and Indaptus, and has received research funding from Roche/Genentech, Pfizer, Valitor, and Bristol Myers Squibb. JPR is a co-founder and scientific advisor of Seal Biosciences, Inc., a scientific advisory committee member for the Mark Foundation for Cancer Research, a consultant for MorphImmune and Monte-Rosa Therapeutics, and has received research funding from 3TBiosciences, Senti Biosciences, and Eli Lilly.