Munc13-4 is essential for cytolytic granules fusion and is mutated in a form of familial hemophagocytic lymphohistiocytosis (FHL3).
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.
Feldmann
Jérôme
J
INSERM U429, Hôpital Necker-Enfants Malades, 75743 Paris, France.
Callebaut
Isabelle
I
Raposo
Graça
G
Certain
Stéphanie
S
Bacq
Delphine
D
Dumont
Cécile
C
Lambert
Nathalie
N
Ouachée-Chardin
Marie
M
Chedeville
Gaëlle
G
Tamary
Hannah
H
Minard-Colin
Véronique
V
Vilmer
Etienne
E
Blanche
Stéphane
S
Le Deist
Françoise
F
Fischer
Alain
A
de Saint Basile
Geneviève
G
D000595:Amino Acid Sequence; D001483:Base Sequence; D015550:Cell Degranulation; D016764:Cell Polarity; D002478:Cells, Cultured; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D005089:Exocytosis; D005260:Female; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D015616:Histiocytosis, Non-Langerhans-Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009928:Organ Specificity; D010375:Pedigree; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D011506:Proteins; D012333:RNA, Messenger; C430713:Unc13d protein, rat