Munc13-4 is essential for cytolytic granules fusion and is mutated in a form of familial hemophagocytic lymphohistiocytosis (FHL3)
Feldmann J, Callebaut I, Raposo G, Certain S, Bacq D, Dumont C, Lambert N, Ouachee-Chardin M, Chedeville G, Tamary H, Minard-Colin V, Vilmer E, Blanche S, Le Deist F, Fischer A and de Saint Basile G
Immunotherapy / Hematology
Cells used in publication:
T cell, human stim.
Tissue Origin: blood
Wild-type hMunc13-4 expression in stimulated T cells from patients with defective hMunc13-4 rescues T cell cytotoxicity. An RFP-tagged version of hMunc13-4 localizes with cytotoxic granules at the immunological synapse.
Secretion of cytolytic granules content at the immunological synapse is a highly regulated process essential for lymphocyte cytotoxicity. This process requires the rapid transfer of perforin containing lytic granules to the target cell interface, followed by their docking and fusion with the plasma membrane. Defective cytotoxicity characterizes a genetically heterogeneous condition named familial hemophagocytic lymphohistiocytosis (FHL), which can be associated with perforin deficiency. The locus of a perforin (+) FHL subtype (FHL3), observed in 10 patients, was mapped to 17q25. This region contains hMunc13-4, a member of the Munc13 family of proteins involved in vesicle priming function. HMunc13-4 mutations were shown to cause FHL3. HMunc13-4 deficiency results in defective cytolytic granule exocytosis, despite polarization of the secretory granules and docking with the plasma membrane. Expressed tagged hMunc13-4 localizes with cytotoxic granules at the immunological synapse. HMunc13-4 is therefore essential for the priming step of cytolytic granules secretion preceding vesicle membrane fusion.
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