Metabolite Transporters—The Gatekeepers for T Cell Metabolism

Metabolism is the fundamental biological process that drives the survival and death at both organismal and cellular level. It is also intimately involved in all cellular functions, proliferation, differentiation, and response to environmental cues and stress. During infection, successful immune response depends on the proper activation of various cell types. T cells are a key component of adaptive immunity. They remain metabolically quiescent before meeting their cognate antigens, however upon antigen encounter, these activated T cells have increased demands for energy and biological building blocks for differentiation, proliferation, and effector molecules production. These biosynthetic needs are met through metabolic reprogramming. Multilayered metabolite sensing machinery is in place to interact with the environment and coordinates the cellular metabolism with cell signaling and gene expression to meet the cellular demand in a timely manner. As most of the metabolites are cell membrane impermeable and require specialized membrane proteins to facilitate their translocation, metabolite transporters serve as gatekeepers and an important layer of regulation of metabolism in general. In this review, we discuss how key metabolite transporters are involved in T cell metabolism and shape T cell responses.