Different NK cell–activating receptors preferentially recruit Rab27a or Munc13-4 to perforin-containing granules for cytotoxicity

Wood, Stephanie; Meeths, Marie; Chiang, Samuel C.C.; Bechensteen, Anne Grete; Boelens, Jaap Jan; Heilmann, Carsten; Horiuchi, Hisanori; Rosthøj, Steen; Rutynowska, Olga; Winiarski, Jacek; Stow, Jennifer L.; Nordenskjöld, Magnus; Henter, Jan‐Inge; Ljunggren, Hans Gustaf; Bryceson, Yenan T.

doi:10.1182/blood-2009-06-225359

Cited by 90 publications

(101 citation statements)

References 54 publications

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“…Notwithstanding, our data strongly support a common role for Munc13-4 and Rab27a in the regulation of lysosomerelated organelles. This differs from previous studies in platelets and NK cells, which suggested that Rab27a and Munc13-4 regulate discrete rather than common steps in exocytosis (14,15). However, those conclusions were drawn based on static observations and the authors addressed the need for further analysis to determine how the interaction between Munc13-4 and Rab27 is required for membrane trafficking (15).…”

Section: Discussioncontrasting

confidence: 55%

“…Despite containing myeloperoxidase, it is not clear whether these vesicles share similar composition of cargo proteins, and additional studies will be necessary to further characterize these subpopulations of azurophilic granules. As for their secretory machinery, although Munc13-4 was originally described as a Rab27a-specific effector (10), Rab27a-independent functions have been proposed for Munc13-4 in other cells with secretory lysosomes (14,15). A possible molecular mechanism regulating the secretion of readily releasable vesicles may involve Rab27b, a small GTPase that shares 72% homology with Rab27a at the amino acid level (28,29), which is also expressed in neutrophils and whose deficiency leads to a mild defective secretory phenotype in these cells (22).…”

Section: Discussionmentioning

confidence: 99%

“…Despite shared roles in regulating common secretory pathways, it is unclear whether they act together to regulate the same steps during exocytosis. In this way, several lines of evidence suggest that Rab27a and Munc13-4 regulate discrete molecular events during secretory lysosome exocytosis (14,15). Other studies suggest a possible combined role for Munc13-4 and Rab27a during lytic granule maturation (16).…”

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confidence: 99%

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Munc13-4 Restricts Motility of Rab27a-expressing Vesicles to Facilitate Lipopolysaccharide-induced Priming of Exocytosis in Neutrophils

Johnson¹,

Hong²,

Monfregola³

et al. 2011

Journal of Biological Chemistry

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LPS is an efficient sensitizer of the neutrophil exocytic response to a second stimulus. Although neutrophil exocytosis in response to pathogen-derived molecules plays an important role in the innate immune response to infections, the molecular mechanism underlying LPS-dependent regulation of neutrophil exocytosis is currently unknown. The small GTPase Rab27a and its effector Munc13-4 regulate exocytosis in hematopoietic cells. Whether Rab27a and Munc13-4 modulate discrete steps or the same steps during exocytosis also remains unknown. Here, using Munc13-4-and Rab27a-deficient neutrophils, we analyzed the mechanism of lipopolysaccharide-dependent vesicular priming to amplify exocytosis of azurophilic granules. We found that both Munc13-4 and Rab27a are necessary to mediate LPS-dependent priming of exocytosis. However, we show that LPS-induced mobilization of a small population of readily releasable vesicles is a Munc13-4-dependent but Rab27a-independent process. LPS-induced priming regulation could not be fully explained by secretory organelle maturation as the redistribution of the secretory proteins Rab27a or Munc13-4 in response to LPS treatment was minimal. Using total internal reflection fluorescence microscopy and a novel mouse model expressing EGFP-Rab27a under the endogenous Rab27a promoter but lacking Munc13-4, we demonstrate that Munc13-4 is essential for the mechanism of LPS-dependent exocytosis in neutrophils and unraveled a novel mechanism of vesicular dynamics in which Munc13-4 restricts motility of Rab27a-expressing vesicles to facilitate lipopolysaccharideinduced priming of exocytosis.

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Section: Discussioncontrasting

confidence: 55%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Munc13-4 Restricts Motility of Rab27a-expressing Vesicles to Facilitate Lipopolysaccharide-induced Priming of Exocytosis in Neutrophils

Johnson¹,

Hong²,

Monfregola³

et al. 2011

Journal of Biological Chemistry

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“…5C, 5D); Ral-mediated exocyst assembly might thus trigger heterotypic vesicle fusion, leading to granule maturation. Patients with deficiencies in Rab27 and Munc13-4, the proteins responsible for heterotypic vesicle assembly during cytotoxicity (37,38), show impaired cytotoxicity and defects in granule secretion (2, 3) similar to the alterations observed in Ral-silenced cells.…”

Section: Discussionmentioning

confidence: 89%

“…We observed Sec8 mainly in lytic granules, whereas Sec5 and Sec10 localized to other vesicles. Prior to their secretion at the immunological synapse, lytic granules must mature through heterotypic vesicle fusion (37,38). In YTS cells, interaction with target cells promoted Ral-mediated exocyst assembly concomitantly with Sec5 and Sec10 relocalization to the lytic granules (Fig.…”

Section: Discussionmentioning

confidence: 99%

Ral GTPases Regulate Cell-Mediated Cytotoxicity in NK Cells

Sánchez-Ruíz

Mejías

García-Belando

et al. 2011

The Journal of Immunology

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NK cells are key components of the immune response to virally infected and tumor cells. Recognition of target cells initiates a series of events in NK cells that culminates in target destruction via directed secretion of lytic granules. Ral proteins are members of the Ras superfamily of small GTPases; they regulate vesicular trafficking and polarized granule secretion in several cell types. In this study, we address the role of Ral GTPases in cell-mediated cytotoxicity. Using a human NK cell line and human primary NK cells, we show that both Ral isoforms, RalA and RalB, are activated rapidly after target cell recognition. Furthermore, silencing of RalA and RalB impaired NK cell cytotoxicity. RalA regulated granule polarization toward the immunological synapse and the subsequent process of degranulation, whereas RalB regulated degranulation but not polarization of lytic granules. Analysis of the molecular mechanism indicated that Ral activation in NK cells leads to assembly of the exocyst, a protein complex involved in polarized secretion. This assembly is required for degranulation, as interference with expression of the exocyst component Sec5 led to reduced degranulation and impaired cytotoxicity in NK cells. Our results thus identify a role for Ral in cell-mediated cytotoxicity, implicating these GTPases in lymphocyte function.

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Lysosome Exocytosis and Membrane Repair

Singh

Haka

2016

Lysosomes: Biology, Diseases, and Therapeutics

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Different NK cell–activating receptors preferentially recruit Rab27a or Munc13-4 to perforin-containing granules for cytotoxicity

Abstract: The autosomal recessive immunodeficiencies Griscelli syndrome type 2 (GS2) and familial hemophagocytic lymphohistiocytosis type 3 (FHL3) are associated with loss-of-function mutations in RAB27A (encoding Rab27a) and UNC13D (encoding

Cited by 90 publications

References 54 publications

Munc13-4 Restricts Motility of Rab27a-expressing Vesicles to Facilitate Lipopolysaccharide-induced Priming of Exocytosis in Neutrophils

Munc13-4 Restricts Motility of Rab27a-expressing Vesicles to Facilitate Lipopolysaccharide-induced Priming of Exocytosis in Neutrophils

Ral GTPases Regulate Cell-Mediated Cytotoxicity in NK Cells

Lysosome Exocytosis and Membrane Repair

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