Crucial role of the hydrophobic pocket region of Munc18 protein in mast cell degranulation
| Autor: | Na-Ryum Bin, Shuzo Sugita, Chang Hun Jung, Christopher A. Piggott |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Munc18 Proteins
Cell Degranulation Mutation Missense Biology Immunoglobulin E PC12 Cells Exocytosis Lymphohistiocytosis Hemophagocytic Mice Syntaxin Animals Humans Secretion Mast Cells Multidisciplinary Qa-SNARE Proteins Ionomycin HEK 293 cells Degranulation Biological Sciences Cell biology Protein Structure Tertiary Rats Calcium Ionophores HEK293 Cells Amino Acid Substitution biology.protein Hydrophobic and Hydrophilic Interactions |
| Popis: | The function of the Munc18-1 protein hydrophobic pocket, which interacts with the syntaxin-1 N-terminal peptide, has been highly controversial in neurosecretion. Recent analysis of patients with familial hemophagocytic lymphohistiocytosis type 5 has identified the E132A mutation in the hydrophobic pocket of Munc18-2, prompting us to examine the role of this region in the context of immune cell secretion. Double knockdown of Munc18-1 and Munc18-2 in RBL-2H3 mast cells eliminates both IgE-dependent and ionomycin-induced degranulation and causes a significant reduction in syntaxin-11 without altering expressions of the other syntaxin isoforms examined. These phenotypes were effectively rescued on reexpression of wild-type Munc18-1 or Munc18-2 but not the mutants (F115E, E132A, and F115E/E132A) in the hydrophobic pocket of Munc18. In addition, these mutants show that they are unable to directly interact with syntaxin-11, as tested through protein interaction experiments. Our results demonstrate the crucial roles of the hydrophobic pocket of Munc18 in mast cell degranulation, which include the regulation of syntaxin-11. We also suggest that the functional importance of this region is significantly different between neuronal and immune cell exocytosis. |
| Databáze: | OpenAIRE |
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