Small GTPases of the Ras superfamily and glycogen phosphorylase regulation in T cells

Small GTPases, together with their regulatory and effector molecules, are key intermediaries in the complex signalling pathways that control almost all cellular processes, working as molecular switches to transduce extracellular cues into cellular responses that drive vital functions, such as intracellular transport, biomolecule synthesis, gene activation and cell survival. How all of these networks are linked to metabolic pathways is a subject of intensive study. Because any response to cellular action requires some form of energy input, elucidating how cells coordinate the signals that lead to a tangible response involving metabolism is central to understand cellular activities. In this review, we summarize recent advances in our understanding of the molecular basis of the crosstalk between small GTPases of the Ras superfamily, specifically Rac1 and Ras/Rap1, and glycogen phosphorylase in T lymphocytes. Abbreviations: ADCY: adenylyl cyclase; ADCY6: adenylyl cyclase 6; BCR: B cell receptor; cAMP: 3',5'-cyclic adenosine monophosphate; CRIB: Cdc42/Rac binding domain; DLPFC: dysfunction of the dorsolateral prefrontal cortex; EGFR: epidermal growth factor receptor; Epac2: exchange protein directly activated by cAMP; GDP: guanodine-5'-diphosphate; GPCRs: G protein-coupled receptors; GTP: guanodin-5'-triphosphate; IL2: interleukin 2; IL2-R: interleukin 2 receptor; JAK: janus kinases; MAPK: mitogen-activated protein kinase; O-GlcNAc: O-glycosylation; PAK1: p21 activated kinase 1; PI3K: phosphatidylinositol 3-kinase; PK: phosphorylase kinase; PKA: cAMP-dependent protein kinase A; PKCθ: protein kinase Cθ; PLCγ: phospholipase Cγ; Src: proto-oncogene tyrosine-protein kinase c; STAT: signal transducer and activator of transcription proteins.