Guardians of T-Cell Ca²⁺ Stores: SERCA Pumps Integrated Within Complex Functional and Disease-State Signaling...

T cells are the central regulators of the adaptive immune system, guiding both the cell-mediated and antibody-based elements of the immune response. Crucial to T-cell activation and differentiation, the T-cell receptor must transduce antigen exposure using a sustained elevated Ca²⁺ signal. A substantial body of research has identified and characterized multiple players in the Ca²⁺ signaling pathway, yet the sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) transporters, which intervene actively to regulate Ca²⁺ signal patterning and duration, remain relatively poorly characterized in the full scope of the T-cell signaling paradigm. In this review, we summarize the expanding research that is beginning to clarify the multiple complex roles SERCAs perform in shaping the information-rich Ca²⁺ signal. Pharmacologic modulators and other studies have revealed molecular and functional diversity in the SERCA pumps, with increasing recognition of their critical positioning in regulating ER Ca²⁺ store networks and functional roles, which ultimately derive from dynamic microdomain assemblies containing potentially highly tailored SERCA-binding protein interactomes. A better understanding of SERCA transporter functions underlies increasing interest in developing novel therapeutic strategies targeting these key ion pumps in efforts to engineer T-cell phenotypes for more therapeutically efficacious management of cancer, autoimmunity, and other immune-based pathologies.