Premium
A novel Dutch mutation in UNC13D reveals an essential role of the C2B domain in munc13‐4 function
Author(s) -
Elstak Edo D.,
te Loo Maroeska,
Tesselaar Kiki,
van Kerkhof Peter,
Loeffen Jan,
Grivas Dimitris,
Hennekam Eric,
Boelens Jaap Jan,
Hoogerbrugge Peter M.,
van der Sluijs Peter,
van Gijn Marielle E.,
van de Corput Lisette
Publication year - 2012
Publication title -
pediatric blood and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.116
H-Index - 105
eISSN - 1545-5017
pISSN - 1545-5009
DOI - 10.1002/pbc.23253
Subject(s) - mutation , mutant , biology , genetics , mutant protein , cancer research , microbiology and biotechnology , gene
Abstract Background UNC13D , encoding the protein munc13‐4, is essential in intracellular trafficking and exocytosis of lytic granules. Mutations in this gene are associated with familial hemophagocytic lymphohistiocytosis type 3 (FHL3), a genetically heterogeneous, rare autosomal recessive immune disorder. How mutations affect function of munc13‐4 is poorly understood. Since 2006 we genetically identified seven FHL patients with mutations in UNC13D . Procedures Here, we report for the first time a c.2695C>T (p.Arg899X) mutation in exon 28 of UNC13D in three young unrelated Dutch patients. The mutation causes a premature stop codon and encodes munc13‐4(1–899), which lacks the C‐terminal C2 domain. Genealogical research and haplotyping of the patient families demonstrated that a single ancestral founder introduced the mutation in the Netherlands. We then characterized the mutant protein phenotypically in cell biological and immunological assays. Results Munc13‐4(1–899) was correctly targeted to CD63‐positive secretory lysosomes, although its stability was reduced and dynamic turnover on the granule membrane became uncoupled from receptor signaling. In accord, and in contrast to wild‐type munc13‐4, ectopically expressed mutant failed to rescue degranulation in cells with silenced endogenous munc13‐4. Conclusions The functional and clinical data showed that this novel Dutch founder mutation leads to severe early onset of FHL3 due to misfolding and degradation of munc13‐4(1–899). Pediatr Blood Cancer 2012; 58: 598–605. © 2011 Wiley Periodicals, Inc.