Rab27a is a key component of the secretory machinery of azurophilic granules in granulocytes

Daniela B. Munafó, Jennifer L. Johnson, Beverly A. Ellis, Sophie Rutschmann, Bruce Beutler, Sergio D. Catz

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Neutrophils kill micro-organisms using microbicidal products that they release into the phagosome or into the extracellular space. The secretory machinery utilized by neutrophils is poorly characterized. We show that the small GTPase Rab27a is an essential component of the secretory machinery of azurophilic granules in granulocytes. Rab27a-deficient mice have impaired secretion of MPO (myeloperoxidase) into the plasma in response to lipopolysaccharide. Cell fractionation analysis revealed that Rab27a and the Rab27a effector protein JFC1/S1p1 (synaptotagmin-like protein 1) are distributed principally in the low-density fraction containing a minor population of MPO-containing granules. By immunofluorescence microscopy, we detected Rab27a and JFC1/Slp1 in a minor subpopulation of MPO-containing granules. Interference with the JFC1/Slp1-Rab27a secretory machinery impaired secretion of MPO in permeabilized neutrophils. The expression of Rab27a was dramatically increased when promyelocytic HL-60 cells were differentiated into granulocytes but not when they were differentiated into monocytes. Down-regulation of Rab27a in HL-60 cells by RNA interference did not affect JFC1/Slp1 expression but significantly decreased the secretion of MPO. Neither Rab27a nor JFC1/Slp1 was integrated into the phagolysosome membrane during phagocytosis. Neutrophils from Rab27a-deficient mice efficiently phagocytose zymosan opsonized particles and deliver MPO to the phagosome. We conclude that Rab27a and JFC1/Slp1 permit MPO release into the surrounding milieu and constitute key components of the secretory machinery of azurophilic granules in granulocytes. Our results suggest that the granules implicated in cargo release towards the surrounding milieu are molecularly and mechanistically different from those involved in their release towards the phagolysosome.

Original languageEnglish (US)
Pages (from-to)229-239
Number of pages11
JournalBiochemical Journal
Volume402
Issue number2
DOIs
StatePublished - Mar 1 2007

Fingerprint

Secretory Component
Granulocytes
Peroxidase
Machinery
Phagosomes
Neutrophils
HL-60 Cells
Phagocytosis
Cell Fractionation
Zymosan
Monomeric GTP-Binding Proteins
Extracellular Space
Fractionation
RNA Interference
Fluorescence Microscopy
Lipopolysaccharides
Monocytes
Microscopic examination
Down-Regulation
RNA

Keywords

  • Azurophilic granule
  • Exocytosis
  • Myeloperoxidase
  • Rab27a
  • Small GTPase
  • Synaptotagmin-like protein (Slp)

ASJC Scopus subject areas

  • Biochemistry
  • Medicine(all)

Cite this

Rab27a is a key component of the secretory machinery of azurophilic granules in granulocytes. / Munafó, Daniela B.; Johnson, Jennifer L.; Ellis, Beverly A.; Rutschmann, Sophie; Beutler, Bruce; Catz, Sergio D.

In: Biochemical Journal, Vol. 402, No. 2, 01.03.2007, p. 229-239.

Research output: Contribution to journalArticle

Munafó, Daniela B. ; Johnson, Jennifer L. ; Ellis, Beverly A. ; Rutschmann, Sophie ; Beutler, Bruce ; Catz, Sergio D. / Rab27a is a key component of the secretory machinery of azurophilic granules in granulocytes. In: Biochemical Journal. 2007 ; Vol. 402, No. 2. pp. 229-239.
@article{2ccfa77d4ca84783a6e15a9c39f939e4,
title = "Rab27a is a key component of the secretory machinery of azurophilic granules in granulocytes",
abstract = "Neutrophils kill micro-organisms using microbicidal products that they release into the phagosome or into the extracellular space. The secretory machinery utilized by neutrophils is poorly characterized. We show that the small GTPase Rab27a is an essential component of the secretory machinery of azurophilic granules in granulocytes. Rab27a-deficient mice have impaired secretion of MPO (myeloperoxidase) into the plasma in response to lipopolysaccharide. Cell fractionation analysis revealed that Rab27a and the Rab27a effector protein JFC1/S1p1 (synaptotagmin-like protein 1) are distributed principally in the low-density fraction containing a minor population of MPO-containing granules. By immunofluorescence microscopy, we detected Rab27a and JFC1/Slp1 in a minor subpopulation of MPO-containing granules. Interference with the JFC1/Slp1-Rab27a secretory machinery impaired secretion of MPO in permeabilized neutrophils. The expression of Rab27a was dramatically increased when promyelocytic HL-60 cells were differentiated into granulocytes but not when they were differentiated into monocytes. Down-regulation of Rab27a in HL-60 cells by RNA interference did not affect JFC1/Slp1 expression but significantly decreased the secretion of MPO. Neither Rab27a nor JFC1/Slp1 was integrated into the phagolysosome membrane during phagocytosis. Neutrophils from Rab27a-deficient mice efficiently phagocytose zymosan opsonized particles and deliver MPO to the phagosome. We conclude that Rab27a and JFC1/Slp1 permit MPO release into the surrounding milieu and constitute key components of the secretory machinery of azurophilic granules in granulocytes. Our results suggest that the granules implicated in cargo release towards the surrounding milieu are molecularly and mechanistically different from those involved in their release towards the phagolysosome.",
keywords = "Azurophilic granule, Exocytosis, Myeloperoxidase, Rab27a, Small GTPase, Synaptotagmin-like protein (Slp)",
author = "Munaf{\'o}, {Daniela B.} and Johnson, {Jennifer L.} and Ellis, {Beverly A.} and Sophie Rutschmann and Bruce Beutler and Catz, {Sergio D.}",
year = "2007",
month = "3",
day = "1",
doi = "10.1042/BJ20060950",
language = "English (US)",
volume = "402",
pages = "229--239",
journal = "Biochemical Journal",
issn = "0264-6021",
publisher = "Portland Press Ltd.",
number = "2",

}

TY - JOUR

T1 - Rab27a is a key component of the secretory machinery of azurophilic granules in granulocytes

AU - Munafó, Daniela B.

AU - Johnson, Jennifer L.

AU - Ellis, Beverly A.

AU - Rutschmann, Sophie

AU - Beutler, Bruce

AU - Catz, Sergio D.

PY - 2007/3/1

Y1 - 2007/3/1

N2 - Neutrophils kill micro-organisms using microbicidal products that they release into the phagosome or into the extracellular space. The secretory machinery utilized by neutrophils is poorly characterized. We show that the small GTPase Rab27a is an essential component of the secretory machinery of azurophilic granules in granulocytes. Rab27a-deficient mice have impaired secretion of MPO (myeloperoxidase) into the plasma in response to lipopolysaccharide. Cell fractionation analysis revealed that Rab27a and the Rab27a effector protein JFC1/S1p1 (synaptotagmin-like protein 1) are distributed principally in the low-density fraction containing a minor population of MPO-containing granules. By immunofluorescence microscopy, we detected Rab27a and JFC1/Slp1 in a minor subpopulation of MPO-containing granules. Interference with the JFC1/Slp1-Rab27a secretory machinery impaired secretion of MPO in permeabilized neutrophils. The expression of Rab27a was dramatically increased when promyelocytic HL-60 cells were differentiated into granulocytes but not when they were differentiated into monocytes. Down-regulation of Rab27a in HL-60 cells by RNA interference did not affect JFC1/Slp1 expression but significantly decreased the secretion of MPO. Neither Rab27a nor JFC1/Slp1 was integrated into the phagolysosome membrane during phagocytosis. Neutrophils from Rab27a-deficient mice efficiently phagocytose zymosan opsonized particles and deliver MPO to the phagosome. We conclude that Rab27a and JFC1/Slp1 permit MPO release into the surrounding milieu and constitute key components of the secretory machinery of azurophilic granules in granulocytes. Our results suggest that the granules implicated in cargo release towards the surrounding milieu are molecularly and mechanistically different from those involved in their release towards the phagolysosome.

AB - Neutrophils kill micro-organisms using microbicidal products that they release into the phagosome or into the extracellular space. The secretory machinery utilized by neutrophils is poorly characterized. We show that the small GTPase Rab27a is an essential component of the secretory machinery of azurophilic granules in granulocytes. Rab27a-deficient mice have impaired secretion of MPO (myeloperoxidase) into the plasma in response to lipopolysaccharide. Cell fractionation analysis revealed that Rab27a and the Rab27a effector protein JFC1/S1p1 (synaptotagmin-like protein 1) are distributed principally in the low-density fraction containing a minor population of MPO-containing granules. By immunofluorescence microscopy, we detected Rab27a and JFC1/Slp1 in a minor subpopulation of MPO-containing granules. Interference with the JFC1/Slp1-Rab27a secretory machinery impaired secretion of MPO in permeabilized neutrophils. The expression of Rab27a was dramatically increased when promyelocytic HL-60 cells were differentiated into granulocytes but not when they were differentiated into monocytes. Down-regulation of Rab27a in HL-60 cells by RNA interference did not affect JFC1/Slp1 expression but significantly decreased the secretion of MPO. Neither Rab27a nor JFC1/Slp1 was integrated into the phagolysosome membrane during phagocytosis. Neutrophils from Rab27a-deficient mice efficiently phagocytose zymosan opsonized particles and deliver MPO to the phagosome. We conclude that Rab27a and JFC1/Slp1 permit MPO release into the surrounding milieu and constitute key components of the secretory machinery of azurophilic granules in granulocytes. Our results suggest that the granules implicated in cargo release towards the surrounding milieu are molecularly and mechanistically different from those involved in their release towards the phagolysosome.

KW - Azurophilic granule

KW - Exocytosis

KW - Myeloperoxidase

KW - Rab27a

KW - Small GTPase

KW - Synaptotagmin-like protein (Slp)

UR - http://www.scopus.com/inward/record.url?scp=33847754590&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33847754590&partnerID=8YFLogxK

U2 - 10.1042/BJ20060950

DO - 10.1042/BJ20060950

M3 - Article

C2 - 17090228

AN - SCOPUS:33847754590

VL - 402

SP - 229

EP - 239

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 2

ER -