Familial hemophagocytic lymphohistiocytosis type 5 (FHL-5) is caused by mutations in Munc18-2 and impaired binding to syntaxin 11.
Rapid intracellular transport and secretion of cytotoxic granules through the immunological synapse requires a balanced interaction of several proteins. Disturbance of this highly regulated process underlies familial hemophagocytic lymphohistiocytosis (FHL), a genetically heterogeneous autosomal-recessive disorder characterized by a severe hyperinflammatory phenotype. Here, we have assigned FHL-5 to a 1 Mb region on chromosome 19p by using high-resolution SNP genotyping in eight unrelated FHL patients from consanguineous families. Subsequently, we found nine different mutations, either truncating or missense, in STXBP2 in twelve patients from Turkey, Saudi Arabia, and Central Europe. STXBP2 encodes syntaxin binding protein 2 (Munc18-2), involved in the regulation of vesicle transport to the plasma membrane. We have identified syntaxin 11, a SNARE protein mutated in FHL-4, as an interaction partner of STXBP2. This interaction is eliminated by the missense mutations found in our FHL-5 patients, which leads to a decreased stability of both proteins, as shown in patient lymphocytes. Activity of natural killer and cytotoxic T cells was markedly reduced or absent, as determined by CD107 degranulation. Our findings thus identify a key role for STXBP2 in lytic granule exocytosis.
zur Stadt
Udo
U
Research Institute Children's Cancer Center, 20251 Hamburg, Germany. zurstadt@kinderkrebs-forschung.de
Rohr
Jan
J
Seifert
Wenke
W
Koch
Florian
F
Grieve
Samantha
S
Pagel
Julia
J
Strauss
Julia
J
Kasper
Brigitte
B
Nürnberg
Gudrun
G
Becker
Christian
C
Maul-Pavicic
Andrea
A
Beutel
Karin
K
Janka
Gritta
G
Griffiths
Gillian
G
Ehl
Stephan
S
Hennies
Hans Christian
HC
D002675:Child, Preschool; D002874:Chromosome Mapping; D002888:Chromosomes, Human, Pair 19; D005089:Exocytosis; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D051359:Lymphohistiocytosis, Hemophagocytic / Q000235:genetics* / Q000473:pathology; D008297:Male; D051938:Munc18 Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020641:Polymorphism, Single Nucleotide; D050765:Qa-SNARE Proteins / Q000235:genetics* / Q000378:metabolism; D050600:SNARE Proteins / Q000378:metabolism
D051938:Munc18 Proteins; D050765:Qa-SNARE Proteins; D050600:SNARE Proteins; C497940:STXBP2 protein, human