scholarly journals Mast Cell β-Tryptase Is Enzymatically Stabilized by DNA

2020 ◽  
Vol 21 (14) ◽  
pp. 5065
Author(s):  
Sultan Alanazi ◽  
Mirjana Grujic ◽  
Maria Lampinen ◽  
Ola Rollman ◽  
Christian P. Sommerhoff ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Enzymatic Activity ◽  
Secretory Granules ◽  
Base Pairs ◽  
Double Stranded Dna ◽  
Nuclear Core ◽  
Anionic Charge ◽  
Core Histones ◽  
Nuclear Events

Tryptase is a tetrameric serine protease located within the secretory granules of mast cells. In the secretory granules, tryptase is stored in complex with negatively charged heparin proteoglycans and it is known that heparin is essential for stabilizing the enzymatic activity of tryptase. However, recent findings suggest that enzymatically active tryptase also can be found in the nucleus of murine mast cells, but it is not known how the enzmatic activity of tryptase is maintained in the nuclear milieu. Here we hypothesized that tryptase, as well as being stabilized by heparin, can be stabilized by DNA, the rationale being that the anionic charge of DNA could potentially substitute for that of heparin to execute this function. Indeed, we showed that double-stranded DNA preserved the enzymatic activity of human β-tryptase with a similar efficiency as heparin. In contrast, single-stranded DNA did not have this capacity. We also demonstrated that DNA fragments down to 400 base pairs have tryptase-stabilizing effects equal to that of intact DNA. Further, we showed that DNA-stabilized tryptase was more efficient in degrading nuclear core histones than heparin-stabilized enzyme. Finally, we demonstrated that tryptase, similar to its nuclear localization in murine mast cells, is found within the nucleus of primary human skin mast cells. Altogether, these finding reveal a hitherto unknown mechanism for the stabilization of mast cell tryptase, and these findings can have an important impact on our understanding of how tryptase regulates nuclear events.

scholarly journals Tryptase Regulates the Epigenetic Modification of Core Histones in Mast Cell Leukemia Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Sultan Alanazi ◽  
Fabio Rabelo Melo ◽  
Gunnar Pejler
Keyword(s):  
Cell Death ◽  
Mast Cell ◽  
Mast Cells ◽  
Epigenetic Modification ◽  
Secretory Granules ◽  
Leukemia Cells ◽  
Human Mast Cell ◽  
Cell Leukemia ◽  
Core Histones ◽  
Mast Cell Leukemia

Mast cells are immune cells that store large amounts of mast cell-restricted proteases in their secretory granules, including tryptase, chymase and carboxypeptidase A3. In mouse mast cells, it has been shown that tryptase, in addition to its canonical location in secretory granules, can be found in the nuclear compartment where it can impact on core histones. Here we asked whether tryptase can execute core histone processing in human mast cell leukemia cells, and whether tryptase thereby can affect the epigenetic modification of core histones. Our findings reveal that triggering of cell death in HMC-1 mast cell leukemia cells is associated with extensive cleavage of core histone 3 (H3) and more restricted cleavage of H2B. Tryptase inhibition caused a complete blockade of such processing. Our data also show that HMC-1 cell death was associated with a major reduction of several epigenetic histone marks, including H3 lysine-4-mono-methylation (H3K4me1), H3K9me2, H3 serine-10-phosphorylation (H3S10p) and H2B lysine-16-acetylation (H2BK16ac), and that tryptase inhibition reverses the effect of cell death on these epigenetic marks. Further, we show that tryptase is present in the nucleus of both viable and dying mast cell leukemia cells. In line with a role for tryptase in regulating nuclear events, tryptase inhibition caused increased proliferation of the mast cell leukemia cells. Altogether, the present study emphasizes a novel principle for how epigenetic modification of core histones is regulated, and provides novel insight into the biological function of human mast cell tryptase.

scholarly journals Anaphylactic Degranulation of Mast Cells: Focus on Compound Exocytosis

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ofir Klein ◽  
Ronit Sagi-Eisenberg
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Molecular Mechanisms ◽  
Secretory Granules ◽  
Cell Types ◽  
Secretory Cells ◽  
Regulated Exocytosis ◽  
Open Questions ◽  
Conflicting Evidence ◽  
Compound Exocytosis

Anaphylaxis is a notorious type 2 immune response which may result in a systemic response and lead to death. A precondition for the unfolding of the anaphylactic shock is the secretion of inflammatory mediators from mast cells in response to an allergen, mostly through activation of the cells via the IgE-dependent pathway. While mast cells are specialized secretory cells that can secrete through a variety of exocytic modes, the most predominant mode exerted by the mast cell during anaphylaxis is compound exocytosis—a specialized form of regulated exocytosis where secretory granules fuse to one another. Here, we review the modes of regulated exocytosis in the mast cell and focus on compound exocytosis. We review historical landmarks in the research of compound exocytosis in mast cells and the methods available for investigating compound exocytosis. We also review the molecular mechanisms reported to underlie compound exocytosis in mast cells and expand further with reviewing key findings from other cell types. Finally, we discuss the possible reasons for the mast cell to utilize compound exocytosis during anaphylaxis, the conflicting evidence in different mast cell models, and the open questions in the field which remain to be answered.

The lysosomal protease cathepsin D is efficiently sorted to and secreted from regulated secretory compartments in the rat basophilic/mast cell line RBL

2000 ◽  
Vol 113 (18) ◽  
pp. 3289-3298 ◽  
Author(s):  
A. Dragonetti ◽  
M. Baldassarre ◽  
R. Castino ◽  
M. Demoz ◽  
A. Luini ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Line ◽  
Cathepsin D ◽  
Secretory Granules ◽  
Bioactive Molecules ◽  
Blue Staining ◽  
Lysosomal Protease ◽  
Mannose 6 Phosphate ◽  
Mast Cell Line

Basophils and mast cells contain a peculiar class of inflammatory granules that discharge their content upon antigen-mediated crosslinking of IgE-membrane receptors. The pathways for granule biogenesis and exocytosis in these cells are still largely obscure. In this study we employed the rat basophilic leukemia (RBL)/mast cell line to verify the hypothesis that inflammatory granules share common bioactive molecules and functional properties with lysosomes. We demonstrate that inflammatory granules, as identified by the monoclonal 5G10 antibody (which recognises an integral membrane protein) or by Toluidine Blue staining, have an intralumenal acidic pH, possess lysosomal enzymes and are accessible by fluid-phase and membrane endocytosis markers. In addition, we studied the targeting, subcellular localisation and regulated secretion of the lysosomal aspartic protease cathepsin D (CD) as affected by IgE receptor stimulation in order to obtain information on the pathways for granule biogenesis and exocytosis. Stimulation with DNP-BSA of specific IgE-primed RBL cells led to a prompt release of processed forms of CD, along with other mature lysosomal hydrolases. This release could be prevented by addition of EGTA, indicating that it was dependent on extracellular calcium influx. Antigen stimulation also induced exocytosis of immature CD forms accumulated by ammonium chloride, suggesting the existence of an intermediate station in the pathway for granule biogenesis still sensitive to regulated exocytosis. The targeting of molecules to secretory granules may occur via either a mannose-6-phosphate-dependent or mannose-6-phosphate-independent pathway. We conclude that endosomes and lysosomes in basophils/mast cells can act as regulated secretory granules or actually identify with them.

scholarly journals The emerging role of mast cell proteases in asthma

2019 ◽  
Vol 54 (4) ◽  
pp. 1900685 ◽  
Author(s):  
Gunnar Pejler
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Current Knowledge ◽  
Secretory Granules ◽  
Cross Linking ◽  
Lysosomal Hydrolases ◽  
Ige Receptor ◽  
Deficient Mice ◽  
Lines Of Evidence

It is now well established that mast cells (MCs) play a crucial role in asthma. This is supported by multiple lines of evidence, including both clinical studies and studies on MC-deficient mice. However, there is still only limited knowledge of the exact effector mechanism(s) by which MCs influence asthma pathology. MCs contain large amounts of secretory granules, which are filled with a variety of bioactive compounds including histamine, cytokines, lysosomal hydrolases, serglycin proteoglycans and a number of MC-restricted proteases. When MCs are activated, e.g. in response to IgE receptor cross-linking, the contents of their granules are released to the exterior and can cause a massive inflammatory reaction. The MC-restricted proteases include tryptases, chymases and carboxypeptidase A3, and these are expressed and stored at remarkably high levels. There is now emerging evidence supporting a prominent role of these enzymes in the pathology of asthma. Interestingly, however, the role of the MC-restricted proteases is multifaceted, encompassing both protective and detrimental activities. Here, the current knowledge of how the MC-restricted proteases impact on asthma is reviewed.

scholarly journals Recent advances in mast cell activation and regulation

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 196 ◽  
Author(s):  
Hwan Soo Kim ◽  
Yu Kawakami ◽  
Kazumi Kasakura ◽  
Toshiaki Kawakami
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
De Novo ◽  
Immunoglobulin E ◽  
Secretory Granules ◽  
Structural Features ◽  
Mast Cell Activation ◽  
Dependent Manner ◽  
Drug Induced

Mast cells are innate immune cells that intersect with the adaptive immunity and play a crucial role in the initiation of allergic reactions and the host defense against certain parasites and venoms. When activated in an allergen- and immunoglobulin E (IgE)-dependent manner, these cells secrete a large variety of allergenic mediators that are pre-stored in secretory granules or de novo–synthesized. Traditionally, studies have predominantly focused on understanding this mechanism of mast cell activation and regulation. Along this line of study, recent studies have shed light on what structural features are required for allergens and how IgE, particularly anaphylactic IgE, is produced. However, the last few years have seen a flurry of new studies on IgE-independent mast cell activation, particularly via Mrgprb2 (mouse) and MRGPRX2 (human). These studies have greatly advanced our understanding of how mast cells exert non-histaminergic itch, pain, and drug-induced pseudoallergy by interacting with sensory neurons. Recent studies have also characterized mast cell activation and regulation by interleukin-33 (IL-33) and other cytokines and by non-coding RNAs. These newly identified mechanisms for mast cell activation and regulation will further stimulate the allergy/immunology community to develop novel therapeutic strategies for treatment of allergic and non-allergic diseases.

Secretory granules of mast cells accumulate mature and immature MHC class II molecules

2001 ◽  
Vol 114 (2) ◽  
pp. 323-334
Author(s):  
H. Vincent-Schneider ◽  
C. Thery ◽  
D. Mazzeo ◽  
D. Tenza ◽  
G. Raposo ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Mhc Class Ii ◽  
Cell Activation ◽  
Secretory Granules ◽  
Intracellular Localization ◽  
Class Ii ◽  
Mast Cell Activation ◽  
Invariant Chain ◽  
Mhc Class Ii Molecules

Bone marrow-derived mast cells as well as dendritic cells, macrophages and B lymphocytes express major histocompatibility complex (MHC) class II molecules. In mast cells, the majority of MHC class II molecules reside in intracellular cell type-specific compartments, secretory granules. To understand the molecular basis for the localisation of MHC class II molecules in secretory granules, MHC class II molecules were expressed, together with the invariant chain, in the mast cell line, RBL-2H3. Using electron and confocal microscopy, we observed that in RBL-2H3 cells, mature and immature class II molecules accumulate in secretory granules. Two particular features of class II transport accounted for this intracellular localization: first, a large fraction of newly synthesized MHC class II molecules remained associated with invariant chain fragments. This defect, resulting in a slower rate of MHC class II maturation, was ascribed to a low cathepsin S activity. Second, although a small fraction of class II dimers matured (i.e. became free of invariant chain), allowing their association with antigenic peptides, they were retained in secretory granules. As a consequence of this intracellular localization, cell surface expression of class II molecules was strongly increased by cell activation stimuli which induced the release of the contents of secretory granules. Our results suggest that antigen presentation, and thereby antigen specific T cell stimulation, are regulated in mast cells by stimuli which induce mast cell activation.

scholarly journals AN ENZYME IN MAST CELLS WITH PROPERTIES LIKE CHYMOTRYPSIN

1959 ◽  
Vol 110 (3) ◽  
pp. 451-460 ◽  
Author(s):  
Earl P. Benditt ◽  
Margaret Arase
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Methyl Ester ◽  
Enzymatic Activity ◽  
Differential Centrifugation ◽  
Cell Enzyme ◽  
Sucrose Solutions ◽  
Naphthoic Acid ◽  
Activity Curve ◽  
Chymotrypsin A

Mast cells contain an enzyme which hydrolyzes 3-chloroacetoxy-2-naphthoic acid anilide. By using highly purified mast cells isolated by differential centrifugation in high density sucrose solutions we have been able to study this enzymatic activity in more detail. The enzyme has properties similar to those of chymotrypsin: Chymotrypsin will hydrolyze the histochemical substrate, and the chymotrypsin and mast cell activities with this substrate are similarly inhibited by diisopropylfluorophosphate. The mast cell enzyme is capable of hydrolyzing the N-acetyl esters of tryptophan, tyrosine, and phenylalanine, the relative rates of hydrolysis being similar to those seen with chymotrypsin. A characteristic trypsin substrate, p-toluenesulfonyl arginine methyl ester, is not acted upon by the mast cell enzyme or chymotrypsin. The pH activity curve of the new cell enzyme is similar to that of chymotrypsin as determined with N-acetyl-L-tryptophan ethyl ester as substrate.

scholarly journals The Absence of Tryptase Mcpt6 Causes Elevated Cellular Stress in Response to Modulation of the Histone Acetylation Status in Mast Cells

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1190
Author(s):  
Santosh Martin ◽  
Rabelo Melo ◽  
Pejler
Keyword(s):  
Mast Cells ◽  
Histone Acetylation ◽  
Early Stage ◽  
Trichostatin A ◽  
Secretory Granules ◽  
Cellular Stress ◽  
Cell Stress ◽  
Wild Type ◽  
Acetylation Status ◽  
Core Histones

Mast cells contain large amounts of proteases stored within their secretory granules. Previously we showed that one of these proteases, tryptase, in addition to its location within granules, can also be found within the mast cell nucleus, where it has the capacity to affect the acetylation profile of nucleosomal core histones in aging cells. Based on this notion, and on the known sensitivity of mast cells to modulation of histone acetylation, we here asked whether tryptase could impact on the responses against cellular stress caused by disturbed histone acetylation status. To address this, wild-type and tryptase-deficient (Mcpt6−/−) mast cells were subjected to cell stress caused by trichostatin A (TSA), a histone deacetylase inhibitor. Wild-type and Mcpt6−/− mast cells were equally sensitive to TSA at an early stage of culture (~8 weeks). However, in aging mast cells (>50 weeks), tryptase-deficiency led to increased sensitivity to cell death. To address the underlying mechanism, we assessed effects of tryptase deficiency on the expression of markers for proliferation and cell stress. These analyses revealed aberrant regulation of thioredoxin, thioredoxin reductase, glutaredoxin, and glutathione reductase, as well as blunted upregulation of ribonucleotide reductase subunit R2 in response to TSA in aging cells. Moreover, the absence of tryptase led to increased expression of Psme4/PA200, a proteasome variant involved in the processing of acetylated core histones. Altogether, this study identifies a novel role for tryptase in regulating the manifestations of cell stress in aging mast cells.

scholarly journals DOCK5 functions as a key signaling adaptor that links FcεRI signals to microtubule dynamics during mast cell degranulation

2014 ◽  
Vol 211 (7) ◽  
pp. 1407-1419 ◽  
Author(s):  
Kana Ogawa ◽  
Yoshihiko Tanaka ◽  
Takehito Uruno ◽  
Xuefeng Duan ◽  
Yosuke Harada ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Secretory Granules ◽  
Mast Cell Degranulation ◽  
Microtubule Dynamics ◽  
Nucleotide Exchange ◽  
Microtubule Network ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Life Threatening

Mast cells play a key role in the induction of anaphylaxis, a life-threatening IgE-dependent allergic reaction, by secreting chemical mediators that are stored in secretory granules. Degranulation of mast cells is triggered by aggregation of the high-affinity IgE receptor, FcεRI, and involves dynamic rearrangement of microtubules. Although much is known about proximal signals downstream of FcεRI, the distal signaling events controlling microtubule dynamics remain elusive. Here we report that DOCK5, an atypical guanine nucleotide exchange factor (GEF) for Rac, is essential for mast cell degranulation. As such, we found that DOCK5-deficient mice exhibit resistance to systemic and cutaneous anaphylaxis. The Rac GEF activity of DOCK5 is surprisingly not required for mast cell degranulation. Instead, DOCK5 associated with Nck2 and Akt to regulate microtubule dynamics through phosphorylation and inactivation of GSK3β. When DOCK5–Nck2–Akt interactions were disrupted, microtubule formation and degranulation response were severely impaired. Our results thus identify DOCK5 as a key signaling adaptor that orchestrates remodeling of the microtubule network essential for mast cell degranulation.

scholarly journals Rapid and specific conversion of precursor interleukin 1 beta (IL-1 beta) to an active IL-1 species by human mast cell chymase.

1991 ◽  
Vol 174 (4) ◽  
pp. 821-825 ◽  
Author(s):  
H Mizutani ◽  
N Schechter ◽  
G Lazarus ◽  
R A Black ◽  
T S Kupper
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Secretory Granules ◽  
Interleukin 1 ◽  
Critical Role ◽  
Biologically Active ◽  
Surrounding Tissue ◽  
Human Mast Cell ◽  
Interleukin 1 Beta ◽  
Mast Cell Chymase

Secretory granules of human dermal mast cells contain a chymotrypsin-like serine proteinase called chymase. In this study, we demonstrate that the inactive cytokine, 31 kD interleukin 1 beta (IL-1 beta), can be converted rapidly to an 18 kD biologically active species by human mast cell chymase. The product formed is three amino acids longer at the amino terminus than the mature IL-1 beta produced by peripheral blood mononuclear cells and has comparable biological activity. Because chymase is a secretory granule constituent, it is likely to be released into the surrounding tissue when mast cells degranulate. It is also known that non-bone marrow derived cells resident in skin (keratinocytes, fibroblasts) produce but do not process 31 kD IL-1 beta. In this context, chymase may be a potent activator of locally produced 31 kD IL-1 beta. Mast cells lie in close apposition to blood vessels in dermis; therefore, chymase mediated conversion of 31 kD IL-1 beta might be expected to have a critical role in the initiation of the inflammatory response in skin.

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