Beyond Transport: Lysosomal solute carriers as orchestrators of immune signaling.

Solute carriers (SLCs) are the most abundant family of transmembrane transporters. They transport solutes such as amino acids, nucleosides and ions across membranes, regulating their cytosolic availability and maintaining homeostasis within organelles. While their expression is ubiquitous, SLCs play unique roles in immune cells, where endo-lysosomes and phagosomes function as sites of pathogen detection and destruction. Much of this process is carefully orchestrated by lysosomal SLCs that transport pathogen-derived patterns to the cytosol for detection, transmit danger signals to promote microbial clearance, and regulate autophagy to resolve inflammation. In this Perspective, we discuss these alternative functions of lysosomal SLCs and discuss the possibility that they also serve as innate immune sensors.