Regulation of Hematopoiesis and Methionine Homeostasis by mTORC1 Inhibitor NPRL2

Cell Rep. 2015 Jul 21;12(3):371-9. doi: 10.1016/j.celrep.2015.06.042. Epub 2015 Jul 9.


Nitrogen permease regulator-like 2 (NPRL2) is a component of a conserved complex that inhibits mTORC1 (mammalian Target Of Rapamycin Complex 1) in response to amino acid insufficiency. Here, we show that NPRL2 is required for mouse viability and that its absence significantly compromises fetal liver hematopoiesis in developing embryos. Moreover, NPRL2 KO embryos have significantly reduced methionine levels and exhibit phenotypes reminiscent of cobalamin (vitamin B12) deficiency. Consistent with this idea, NPRL2 KO liver and mouse embryonic fibroblasts (MEFs) show defective processing of the cobalamin-transport protein transcobalamin 2, along with impaired lysosomal acidification and lysosomal gene expression. NPRL2 KO MEFs exhibit a significant defect in the cobalamin-dependent synthesis of methionine from homocysteine, which can be rescued by supplementation with cyanocobalamin. Taken together, these findings demonstrate a role for NPRL2 and mTORC1 in the regulation of lysosomal-dependent cobalamin processing, methionine synthesis, and maintenance of cellular re-methylation potential, which are important during hematopoiesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Female
  • Hematopoiesis / physiology*
  • Mechanistic Target of Rapamycin Complex 1
  • Methionine / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Multiprotein Complexes / antagonists & inhibitors*
  • Multiprotein Complexes / metabolism
  • TOR Serine-Threonine Kinases / antagonists & inhibitors*
  • TOR Serine-Threonine Kinases / metabolism
  • Tumor Suppressor Proteins / metabolism*


  • Multiprotein Complexes
  • Tumor Suppressor Proteins
  • Methionine
  • Mechanistic Target of Rapamycin Complex 1
  • TOR Serine-Threonine Kinases