Open AccessBrief Report: The Differential Roles of m TORC 1 and m TORC 2 in Mesenchymal Stem Cell Differentiation
Author(s) -
Martin Sally K.,
Fitter Stephen,
Dutta Ankit K.,
Matthews Mary P.,
Walkley Carl R.,
Hall Michael N.,
Ruegg Markus A.,
Gronthos Stan,
Zannettino Andrew C. W.
Publication year - 2015
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1002/stem.1931
Subject(s) - mtorc2 , mtorc1 , biology , pi3k/akt/mtor pathway , microbiology and biotechnology , mesenchymal stem cell , stem cell , cancer research , signal transduction
Abstract Adipocytes (AdCs) and osteoblasts (OBs) are derived from mesenchymal stem cells (MSCs) and differentiation toward either lineage is both mutually exclusive and transcriptionally controlled. Recent studies implicate the mammalian target of rapamycin (mTOR) pathway as important in determining MSC fate, with inhibition of mTOR promoting OB differentiation and suppressing AdC differentiation. mTOR functions within two distinct multiprotein complexes, mTORC1 and mTORC2, each of which contains the unique adaptor protein, raptor or rictor, respectively. While compounds used to study mTOR signaling, such as rapamycin and related analogs, primarily inhibit mTORC1, prolonged exposure can also disrupt mTORC2 function, confounding interpretation of inhibitor studies. As a result, the relative contribution of mTORC1 and mTORC2 to MSC fate determination remains unclear. In this study, we generated primary mouse MSCs deficient in either Rptor (RapKO) or Rictor (RicKO) using the Cre/ loxP system. Cre‐mediated deletion of Rptor or Rictor resulted in impaired mTORC1 and mTORC2 signaling, respectively. Under lineage‐inductive culture conditions, RapKO MSCs displayed a reduced capacity to form lipid‐laden AdCs and an increased capacity to form a mineralized matrix. In contrast, RicKO MSCs displayed reduced osteogenic differentiation capacity and enhanced adipogenic differentiation potential. Taken together, our findings reveal distinct roles for mTORC1 and mTORC2 in MSC lineage commitment. S tem C ells 2015;33:1359–1365