The Golgi complex governs natural killer cell lytic granule positioning to promote directionality in cytotoxicity.

Cytotoxic immune cells mediate precise attacks against diseased cells to maintain organismal health. Their operational unit of killing and host defense is lytic granules (LGs), which are specialized lysosomal-related organelles. Precision in cytotoxicity is achieved by converging the many LGs to the microtubule-organizing center (MTOC) and polarizing these to the diseased cell for secretion. We identify unappreciated intimate relationships between the Golgi, MTOC, and LGs after cytotoxic cell activation, as well as the trans-Golgin protein GCC2 on the LG surface. GCC2 serves to tether LGs to the Golgi following convergence, and both GCC2 and the Golgi are required for the persistence of convergence. GCC2 allows LGs to utilize the Golgi as a docking station preventing LG dispersion and innocent bystander killing in complex three-dimensional environments. We also identify GCC2 variants causing human natural killer cell deficiency, further emphasizing the importance of LG convergence and Golgi linkage in precision targeting for human immunity.
Competing Interests: Declaration of interests L.A.P., F.v.d.H., Y.L., and J.S.O. are inventors on a patent application (applied through the Trustees of Columbia University in the city of New York, application number PCT/US2023/01614, entitled “Compounds, targets, and methods for modulating lytic granule convergence in cytotoxic cells to promote bystander killing in cellular therapies”). J.R.L. has stock ownership in 23andMe and is a co-inventor on multiple patents related to molecular diagnostics for inherited neuropathies, eye diseases, genomic disorders, and bacterial genomic fingerprinting.
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