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Benson, K. F. et al. Mutations associated with neutropenia in dogs and humans disrupt intracellular transport of neutrophil elastase. Nature Genet. 35, 90-96

Division of Medical Genetics/Department of Medicine, University of Washington School of Medicine, Box 357720, 1705 NE Pacific Street, HSB-K236B, Seattle, Washington 98195, USA.
Nature Genetics (Impact Factor: 29.65). 10/2003; 35(1):90-6. DOI: 10.1038/ng1224
Source: PubMed

ABSTRACT Cyclic hematopoiesis is a stem cell disease in which the number of neutrophils and other blood cells oscillates in weekly phases. Autosomal dominant mutations of ELA2, encoding the protease neutrophil elastase, found in lysosome-like granules, cause cyclic hematopoiesis and most cases of the pre-leukemic disorder severe congenital neutropenia (SCN; ref. 3) in humans. Over 20 different mutations of neutrophil elastase have been identified, but their consequences are elusive, because they confer no consistent effects on enzymatic activity. The similar autosomal recessive disease of dogs, canine cyclic hematopoiesis, is not caused by mutations in ELA2 (data not shown). Here we show that homozygous mutation of the gene encoding the dog adaptor protein complex 3 (AP3) beta-subunit, directing trans-Golgi export of transmembrane cargo proteins to lysosomes, causes canine cyclic hematopoiesis. C-terminal processing of neutrophil elastase exposes an AP3 interaction signal responsible for redirecting neutrophil elastase trafficking from membranes to granules. Disruption of either neutrophil elastase or AP3 perturbs the intracellular trafficking of neutrophil elastase. Most mutations in ELA2 that cause human cyclic hematopoiesis prevent membrane localization of neutrophil elastase, whereas most mutations in ELA2 that cause SCN lead to exclusive membrane localization.

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Available from: Kathleen F Benson, Jul 09, 2014
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    • "The type 2 form includes immunodeficiency associated with neutropenia and partial albinism. The basis of this disease was first discovered as a similar autosomal recessive disease of dogs, canine cyclic hematopoiesis (38). The lack of AP-3 sorting resulted in reduced levels of neutrophil elastase and gelatinase in granules, but normal levels of other enzymes such as MPO and proteinase-3, which reside in the same granule fraction as elastase (57). "
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    ABSTRACT: Neutrophils are part of a family of granulocytes that, together with eosinophils and basophils, play an essential role in innate immunity. Neutrophils are the most abundant circulating leukocytes and are vital for rapid immune responses, being recruited to sites of injury or infection within minutes, where they can act as specialized phagocytic cells. However, another prominent function of neutrophils is the release of pro-inflammatory compounds, including cytokines, chemokines, and digestive enzymes, which are stored in intracellular compartments and released through regulated exocytosis. Hence, an important feature that contributes to rapid immune responses is capacity of neutrophils to synthesize and store pre-formed pro-inflammatory mediators in specialized intracellular vesicles and thus no new synthesis is required. This review will focus on advancement in three topics relevant to neutrophil secretion. First, we will examine what is known about basal level pro-inflammatory mediator synthesis, trafficking, and storage in secretory compartments. Second, we will review recent advancements in the mechanisms that control vesicle mobilization and the release of pre-formed mediators. Third, we will examine the upregulation and de novo synthesis of pro-inflammatory mediators by neutrophils engaged at sites of infection.
    Frontiers in Immunology 09/2014; 5:448. DOI:10.3389/fimmu.2014.00448
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    • "Mistrafficking of NE as a consequence of mutations in ELANE has been suggested as a common mechanism, but previous reports yielded partially conflicting results [Benson et al., 2003; Kollner et al., 2006; Massullo et al., 2005]. We assayed the NE localization in neutrophils and myeloid progenitors in healthy donors (n = 3) and patients with CN (n = 7) or CyN (n = 4). "
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    ABSTRACT: Neutrophil elastase gene (ELANE) mutations are responsible for the majority of cases of severe congenital (CN) and cyclic neutropenia (CyN). We screened CN (n = 395) or CyN (n = 92) patients for ELANE mutations and investigated the impact of mutations on mRNA expression, protein expression and activity. We found 116 different mutations in 162 (41%) CN patients and 26 in 51 (55%) CyN patients, 69 of them were novel. CyN associated mutations were predicted to be more benign than CN associated mutations, but the mutation severity largely overlapped. The frequency of acquired CSF3R mutations, malignant transformation and the need for hematopoietic stem cell transplantation was significantly higher in CN patients with ELANE mutation than in ELANE mutation negative patients. Cellular elastase activity was reduced in neutrophils from CN/CyN patients, irrespective of the mutation status. In CN enzymatic activity was significantly lower in patients with ELANE mutations compared to those with wildtype ELANE. Despite differences in the spectrum of mutations in CN or CyN, type or localization of mutation only partially determine the clinical phenotype. Specific ELANE mutations have limited predictive value for leukemogenesis: the risk for leukemia was correlated with disease severity rather than with occurrence of an ELANE mutation.
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    • "Consistently, studies of disease models whose symptoms resemble Rab27a deficiency (GS-2 and ashen) such as the beige Chediak–Higashi syndrome (CHS) model mouse and the 'gray collie' canine Hermansky–Pudlak syndrome type 2 (HPS- 2) model, indicate that defects in elastase trafficking are responsible for PMN dysfunction in these animals (Benson et al., 2003; Zen et al., 2011). To test the hypothesis that reduced release of elastase underlies the defective migratory phenotype of the Rab27a KO BM-PMNs, we measured Rab27a KO and WT BM-PMN chemotaxis in the presence of the specific elastase inhibitor, elastatinal (Fig. 3G). "
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    ABSTRACT: Neutrophil migration is vital for immunity and precedes effector functions such as pathogen killing. Here, we report that this process is regulated by the Rab27a GTPase, a protein known to control granule exocytosis. Rab27a-deficient (Rab27a KO) neutrophils exhibit migration defects in vitro and in vivo, and live-cell microscopy suggests that delayed uropod detachment causes the migratory defect. Surface expression of CD11b, a key adhesion molecule, is increased in chemokine-stimulated Rab27a KO neutrophils compared with the control, suggesting a turnover delay caused by a defect in elastase secretion from azurophilic granules at the rear of bone marrow polymorphonuclear leukocytes (BM-PMNs). We suggest that Rab27a-dependent protease secretion regulates neutrophil migration through proteolysis-dependent de-adhesion of uropods, a mechanism that could be conserved in cell migration and invasion.
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