Aberrant activation of mTOR, a central regulator of cell growth and metabolism, is a common molecular event in a number of human malignancies including T-lymphoblastic leukemia (T-ALL), a hematological cancer with poor prognosis. Emerging evidence also highlights a crucial role of mTOR signaling in T cell activation and differentiation. The requirement of mTOR for T cell responses is reflective of the unique feature of T cell activation, in that actively cycling T cells undergo massive clonal expansion with a rate of proliferation (doubling every 5-6 hours) exceeding that of any other cells in the adult mammalian system. Concomitant with T cell activation is the reprogramming of the metabolic machinery. Conversely, in the absence of antigen stimulation, T cells exist in a state known as quiescence defined by a small cell size and exit from the cell cycle. Quiescence has been suggested to reduce the energy and space required to maintain a large repertoire of lymphocytes, but how it is regulated remains poorly defined. We recently identified that Tsc1 enforces T cell quiescence by actively controlling mTOR activity. We hypothesize that Tsc1 and mTOR signaling orchestrates a metabolic checkpoint for naive T cell quiescence, and loss of this control mechanism exacerbates leukemia genesis via metabolic dysregulation and inflammatory pathways. We will test this hypothesis by establishing the metabolic and signaling mechanisms in Tsc1-dependent regulation of T cell quiescence, and determining how these Tsc1-mediated effector pathways contribute to the development of leukemia in murine models and human T-ALL. We predict our studies will establish a new paradigm on our understanding of T cell quiescence by linking this process to metabolic pathways for the first time, and by establishing the functional significance of quiescence enforcement on leukemogenesis and tumor-related inflammation. Insights gained from this project will likely lead to the identificatio of innovative strategies (e.g. targeting metabolic and inflammatory pathways, in addition to inhibiting mTOR) for leukemia intervention.

Public Health Relevance

T cells play a central role in the maintenance of immune homeostasis and regulation of immune responses. T cells depend on the metabolic pathways mediated by mTOR signaling to execute these functions, and dysregulation of this process leads to leukemia and immune-mediated diseases. Therefore, a better understanding of the molecules and pathways in T cells is essential for our efforts to prevent and treat these disorders.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA176624-01A1
Application #
8704471
Study Section
Transplantation, Tolerance, and Tumor Immunology Study Section (TTT)
Program Officer
Mccarthy, Susan A
Project Start
2014-08-01
Project End
2019-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
1
Fiscal Year
2014
Total Cost
Indirect Cost
Name
St. Jude Children's Research Hospital
Department
Type
DUNS #
City
Memphis
State
TN
Country
United States
Zip Code
38105
Shi, Hao; Liu, Chaohong; Tan, Haiyan et al. (2018) Hippo Kinases Mst1 and Mst2 Sense and Amplify IL-2R-STAT5 Signaling in Regulatory T Cells to Establish Stable Regulatory Activity. Immunity 49:899-914.e6
Du, Xingrong; Wen, Jing; Wang, Yanyan et al. (2018) Hippo/Mst signalling couples metabolic state and immune function of CD8?+ dendritic cells. Nature 558:141-145
Zeng, Hu; Yu, Mei; Tan, Haiyan et al. (2018) Discrete roles and bifurcation of PTEN signaling and mTORC1-mediated anabolic metabolism underlie IL-7-driven B lymphopoiesis. Sci Adv 4:eaar5701
Newton, Ryan H; Shrestha, Sharad; Sullivan, Jenna M et al. (2018) Maintenance of CD4 T cell fitness through regulation of Foxo1. Nat Immunol 19:838-848
Chapman, Nicole M; Zeng, Hu; Nguyen, Thanh-Long M et al. (2018) mTOR coordinates transcriptional programs and mitochondrial metabolism of activated Treg subsets to protect tissue homeostasis. Nat Commun 9:2095
Yang, Kai; Blanco, Daniel Bastardo; Chen, Xiang et al. (2018) Metabolic signaling directs the reciprocal lineage decisions of ?? and ?? T cells. Sci Immunol 3:
Yu, Mei; Chen, Yuhong; Zeng, Hu et al. (2017) PLC?-dependent mTOR signalling controls IL-7-mediated early B cell development. Nat Commun 8:1457
Yang, Kai; Blanco, Daniel Bastardo; Neale, Geoffrey et al. (2017) Homeostatic control of metabolic and functional fitness of Treg cells by LKB1 signalling. Nature 548:602-606
Zeng, Hu; Chi, Hongbo (2017) mTOR signaling in the differentiation and function of regulatory and effector T cells. Curr Opin Immunol 46:103-111
Karmaus, Peer W F; Herrada, Andrés A; Guy, Cliff et al. (2017) Critical roles of mTORC1 signaling and metabolic reprogramming for M-CSF-mediated myelopoiesis. J Exp Med 214:2629-2647

Showing the most recent 10 out of 21 publications