| 1. |
- Alanazi, Sultan, et al.
(författare)
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Histone Methyltransferase Inhibition Has a Cytotoxic Impact on Transformed Mast Cells : Implications for Mastocytosis
- 2020
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Ingår i: Anticancer Research. - : INT INST ANTICANCER RESEARCH. - 0250-7005 .- 1791-7530. ; 40:5, s. 2525-2536
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aim: Mast cell transformation, as manifested in mastocytosis, can be a serious condition for which there are limited therapeutic options. Mastocytosis cells can be sensitive to histone deacetylase (HDAC) inhibitors, but their sensitivity to other histone-modifying enzymes has not been assessed. Here we addressed this issue.Materials and Methods: Inhibitors of histone methyl transferases, histone demethylases, histone acetyl transferases and HDACs were tested for their effects on growth, viability, caspase-3 activation and annexin V/DRAQ7 staining in transformed mast cells.Results: Transformed mast cells underwent cell death in response to histone methyl transferase and HDAC inhibition, but were not sensitive to histone demethylase or histone acetyl transferase inhibition. Histone methyl transferase inhibition led to cell death with characteristics of apoptosis, as judged by caspase-3 activation. However, DNA fragmentation was not apparent and Annexin V+/DRAQ7(-) cells were not predominant, suggesting a type of cell death differing from classical apoptosis.Conclusion: Histone methyl transferase inhibition could be developed as a novel regimen for targeting mastocytosis.
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| 2. |
- Alanazi, Sultan, et al.
(författare)
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Mast Cell β-Tryptase Is Enzymatically Stabilized by DNA
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:14
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Alanazi, Sultan
(författare)
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The Impact of Tryptase and Epigenetic Mechanisms on Mast Cells
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mast cells have a large influence on multiple immune-mediated responses, including allergic conditions, and they have been implicated in various diseases such as arthritis and cancer. Mastocytosis is characterized by abnormal mast cell proliferation induced by mutations in KIT, the stem cell factor (SCF) receptor. Mast cell leukemia is the most aggressive form of systemic mastocytosis, with no curative treatment options. Therefore, a therapy or study that help finding a cure for this disease is urgently needed.In paper I, we studied the effect of histone modification inhibition on mast cells. Our findings showed for the first time that mast cell leukemia cells are highly sensitive to histone methyltransferase inhibition. In paper II, we further investigated mast cell function, examining whether DNA can substitute heparin in stabilizing tryptase enzymatic activity. The mechanism by which tryptase retains its enzymatic activity in the nuclear environment is unknown. Our study demonstrated that double-stranded DNA maintained the enzymatic activity of human β-tryptase and identified that tryptase is located within the nucleus of primary human skin mast cells. The interaction of tryptase with DNA is further investigated in paper III, with the aim of determining whether tryptase can affect the formation of neutrophil extracellular traps (NETs). This study showed for the first time that tryptase of mast cells binds to DNA and it has a significant potentiating effect on the formation of NETs in reaction to neutrophil triggering stimuli. Furthermore, the study showed that DNA-stabilized tryptase has a high capacity for proteolytic modification of a variety of cytokines, implying a regulatory role for NET-bound tryptase in inflammatory processes. Finally, in paper IV, we examined the effect of mast cell apoptosis on histone processing, and the extent to which these processes are reliant on tryptase. The findings demonstrated that using a granule-mediated approach to induce mast cell death resulted in substantial processing of core histones. Additionally, they showed that tryptase is highly required for the processing and that tryptase regulates the amplitude of epigenetic core histone modifications during the process of cell death.Taken together, the findings provide a basis for investigating histone modification inhibition as a potential therapeutic strategy for the disease. Furthermore, they reveal a previously unknown way of mediating mast cell tryptase stabilization and indicate that tryptase plays a role in the regulation of mast cell death, having the potential to influence our experience and understanding of how tryptase affects nuclear processes.
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| 4. |
- Alanazi, Sultan, et al.
(författare)
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Tryptase Regulates the Epigenetic Modification of Core Histones in Mast Cell Leukemia Cells
- 2021
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- 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 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 an 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.
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| 5. |
- Pejler, Gunnar, et al.
(författare)
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Mast cell tryptase potentiates neutrophil extracellular trap formation
- 2022
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Ingår i: Journal of Innate Immunity. - : S. Karger. - 1662-811X .- 1662-8128. ; 14:5, s. 433-446
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has indicated an intimate functional communication between mast cells and neutrophils during inflammatory conditions, but the nature of such communication is not fully understood. Activated neutrophils are known to release DNA-containing extracellular traps (NETs) and, based on the known ability of tryptase to interact with negatively charged polymers, we here hypothesized that tryptase might interact with NET-contained DNA and thereby regulate NET formation. In support of this, we show that tryptase markedly enhances NET formation in phorbol myristate acetate (PMA)-activated human neutrophils. Moreover, tryptase was found to bind vividly to the NETs, to cause proteolysis of core histones and to cause a reduction in the levels of citrullinated histone-3. Secretome analysis revealed that tryptase caused increased release of numerous neutrophil granule compounds, including gelatinase, lactoferrin and myeloperoxidase. We also show that DNA can induce the tetrameric, active organization of tryptase, suggesting that NET-contained DNA can maintain tryptase activity in the extracellular milieu. In line with such a scenario, DNA-stabilized tryptase was shown to efficiently degrade numerous pro-inflammatory compounds. Finally, we show that tryptase is associated with NET formation in vivo in a melanoma setting, and that NET formation in vivo is attenuated in mice lacking tryptase expression. Altogether, these findings reveal that NET formation can be regulated by mast cell tryptase, thus introducing a novel mechanism of communication between mast cells and neutrophils.
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| 6. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 7. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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