Regulation of T Lymphocyte Metabolism Kenneth A. Frauwirth and Craig B. Thompson J Immunol 2004; 172:4661-4665; ; This information is current as doi: 10.4049/jimmunol.172.8.4661 of September 30, 2021. http://www.jimmunol.org/content/172/8/4661 Downloaded from References This article cites 38 articles, 19 of which you can access for free at: http://www.jimmunol.org/content/172/8/4661.full#ref-list-1 Why The JI? Submit online. http://www.jimmunol.org/ • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on September 30, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2004 by The American Association of Immunologists All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. THE JOURNAL OF IMMUNOLOGY BRIEF REVIEWS Regulation of T Lymphocyte Metabolism Kenneth A. Frauwirth* and Craig B. Thompson1† Upon stimulation, lymphocytes develop from small resting Metabolism in resting lymphocytes cells into highly proliferative and secretory cells. Although When T lymphocytes exit the thymus, they enter peripheral cir- a great deal of study has focused on the genetic program culation as small quiescent cells. These resting T cells consume induced by Ag receptor signals, lymphocytes must also reg- glucose and other essential nutrients at a low rate (1–3), sup- ulate their metabolic function to meet the energetic de- plying energy to maintain normal housekeeping functions (4). mands of activation. In this review, we discuss the changes Glucose utilization is divided approximately evenly between in cellular metabolism that accompany lymphocyte acti- oligosaccharide synthesis (glycosylation reactions), lactate pro- duction (glycolysis only), and oxidation to CO (glycolysis plus vation, with a particular emphasis on glucose metabolism, 2 Downloaded from a major source of both energy and biosynthetic building Krebs cycle; pentose phosphate pathway) (1). To maintain even blocks. We will also cover the signaling pathways that pos- this basal metabolic rate, T cells require extracellular signals, in- itively and negatively regulate these changes to maintain cluding cytokines and low-level stimulation through the TCR. metabolic homeostasis in cells that are rapidly growing, In the absence of such signals, T cells reduce their capacity to dividing, and differentiating. The Journal of Immunol- import glucose to levels below those necessary to maintain cel- lular homeostasis (5, 6). Thus, the metabolism of resting lym- http://www.jimmunol.org/ ogy, 2004, 172: 4661–4665. phocytes is limited by the availability of trophic signals rather than by the availability of nutrients. ymphocytes must be able to rapidly respond to the presence of pathogens, shifting from a quiescent phe- Activation by mitogens and aerobic glycolysis L notype to a highly active state within hours of stimula- Early studies of T cell activation used mitogenic plant lectins, tion. Most investigation has centered on the signal transduction such as Con A, PHA, and pokeweed mitogen. Treatment of pathways that lead to the transcriptional activation of cell cycle bulk T cells with these mitogens leads to activation similar to control genes and immune effector molecules. More recently it antigenic stimulation, including cell growth (blastogenesis) and by guest on September 30, 2021 has been recognized that macromolecular synthesis must also be proliferation, but affecting the majority of T cells in a popula- up-regulated to allow the cell to enact the transcriptional pro- tion, rather than the small number of cells responsive to a spe- grams of growth, proliferation, and effector function. In con- cific Ag. Not surprisingly, the energy-demanding processes of trast, relatively little attention has been focused on how lym- mitogenic activation are accompanied by an increase in glucose phocyte metabolism is regulated to support the bioenergetically utilization, detectable within1hofstimulation (1, 7–9). demanding processes of growth. Activated lymphocytes must Stimulation also induces a rapid but moderate elevation in dramatically alter their metabolism to support these increased oxygen consumption (1, 7, 10); however, the increase in glyco- synthetic activities. Classical biochemistry teaches that cellular lysis is dramatically greater than the increase in oxygen con- metabolism is homeostatically regulated, such that an increased sumption, resulting in a significant increase in the production demand for energy or biosynthetic intermediates leads to dere- of lactate. This development of a highly glycolytic metabolism pression of catabolic pathways in response to the increased con- has been called “aerobic glycolysis,” distinguishing it from the version of ATP to ADP. Although such compensatory changes shift to glycolysis caused by oxygen limitation (as in muscle). can prevent an acute bioenergetic collapse in response to the Aerobic glycolysis was originally described as a constitutive fea- initial increase in energy consumption associated with signal ture of many malignant cells (11) and may represent a conse- transduction and transcription, there is growing evidence that quence of specific oncogenic mutations acquired during extracellular signals are required to up-regulate lymphocyte nu- transformation. trient uptake and metabolism to support cell growth, prolifer- There are two major interpretations of the switch to aerobic ation, and cytokine secretion. This opens the possibility that the glycolysis during lymphocyte activation. Lymphocytes may be signaling pathways involved in lymphocyte metabolic control unable to increase oxidative phosphorylation enough to supply may be novel therapeutic targets. their energy needs and must therefore hyperinduce glycolysis. *Department of Cell Biology and Molecular Genetics, University of Maryland, College 1 Address correspondence and reprint requests to Dr. Craig B. Thompson, Abramson Park, MD 20742; and †Abramson Family Cancer Research Institute and Department of Family Cancer Research Institute, Room 450, University of Pennsylvania, 421 Curie Bou- Cancer Biology, University of Pennsylvania, Philadelphia, PA 19104 levard, Philadelphia, PA 19104. E-mail address: [email protected] Received for publication December 19, 2003. Accepted for publication February 23, 2004. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Copyright © 2004 by The American Association of Immunologists, Inc. 0022-1767/04/$02.00 4662 BRIEF REVIEWS Downloaded from http://www.jimmunol.org/ FIGURE 1. Insulin and costimulation regulate analogous metabolic control pathways. a, Binding of insulin to the insulin receptor triggers intrinsic tyrosine kinase activity, leading to recruitment and phosphorylation of the adaptor protein IRS-1, followed by recruitment and activation of PI3K. PI3K generates PIP3, which recruits Akt to the plasma membrane, where it is can be activated by the PI3K-responsive kinase PDK-1. Active Akt is able to promote redistribution of Glut4 from intracellular stores to the cell surface, increased Glut1 expression, and enhanced glucose transport and glycolysis in insulin-responsive cells. b, Coligation of the TCR complex and CD28 on T cells leads to phosphorylation of CD28 and recruitment of PI3K. As in a, active PI3K leads to activation of Akt, with the metabolic by guest on September 30, 2021 effects of increased Glut1 synthesis and surface expression, and enhanced glucose transport and glycolysis. Alternatively, the shift to glycolysis could result from a primary ulation, coinciding with the maximal protein and RNA synthe- stimulation of glucose uptake and catabolism that exceeds the sis of T cell blastogenesis. cell’s demand for glucose-derived macromolecular precursors or NADH, which is used to produce ATP through oxidative Costimulation and aerobic glycolysis phosphorylation. Under conditions in which the cell’s glyco- Activation of T cells requires two distinct signals: The TCR lytic rate exceeds its bioenergetic needs, the excess pyruvate plus (signal 1), which provides Ag specificity, and costimulatory re- NADH produced will drive the formation of lactate, allowing ceptors (signal 2), which inform the T cell of the presence of an ϩ the cell to regenerate its pool of NAD . However, it is clear that inflammatory environment. Although lectin stimulation of T glucose metabolism does not increase simply in response to the cells appears similar to activation through the Ag receptor, it is increased ATP to ADP conversion that occurs during lympho- likely due to cross-linking of many different surface molecules, cyte activation. Inhibiting glycolysis with 2-deoxyglucose in the making it difficult to isolate the specific receptors and pathways presence of alternative Krebs cycle substrates (aspartate plus ac- involved in metabolism regulation. However, the