Inhibition of bromodomain extraterminal histone readers alleviates skin fibrosis in experimental models of scleroderma

Vichaikul, Sirapa; Gurrea-Rubio, Mikel; Amin, M. Asif; Campbell, Phillip L.; Wu, Qi; Mattichak, Megan N; Brodie, William D; Palisoc, Pamela J.; Ali, Mustafa; Muraoka, Sei; Ruth, Jeffrey H.; Model, Ellen N; Rohraff, Dallas M; Hervoso, Jonatan L; Mao-Draayer, Yang; Fox, David A.; Khanna, Dinesh; Sawalha, Amr H.; Tsou, Pei‐Suen

doi:10.1172/jci.insight.150871

Cited by 11 publications

(8 citation statements)

References 46 publications

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“…5a,b). We then wanted to confirm if this increase in protein levels is a result of enhanced Brd2 transcription as reported for JQ1 52 . Indeed, by qPCR we found Brd2 to be highly expressed when treating the cells with 1 µM JQ1, and a much smaller but significant increase was found with 5 µM of HPI-1 (Fig.…”

Section: Hpi-1 Is a High Affinity Bet Bromodomain Bindermentioning

confidence: 84%

Targeted protein degradation reveals BET bromodomains as the cellular target of Hedgehog Pathway Inhibitor-1

Bagka

Choi²,

Héritier

et al. 2022

Preprint

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Target deconvolution of small molecule hits from phenotypic screens presents a major challenge. Illustrative of these are the many screens that have been conducted to find inhibitors for the Hedgehog (Hh) signaling pathway, a major developmental pathway with many implications in health and disease, with many hits but very few identified cellular targets. We here present a strategy for target identification based on Proteolysis-Targeting Chimeras (PROTACs), combined with label-free quantitative proteomics. We developed a PROTAC based on the downstream Hedgehog Pathway Inhibitor-1 (HPI-1), a phenotypic screen hit with unknown cellular target. Using our Hedgehog Pathway PROTAC (HPP) we identified and validated BET bromodomains to be the cellular targets of HPI-1. Furthermore, we found that HPP-9 has a unique mechanism of action as a long-acting Hh pathway inhibitor through prolonged BET bromodomain degradation. Collectively, we provide a powerful PROTAC-based approach for target deconvolution, that has answered the longstanding question of the cellular target of HPI-1 and yielded the first PROTAC that acts on the Hh pathway.

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Section: Hpi-1 Is a High Affinity Bet Bromodomain Bindermentioning

confidence: 84%

Targeted protein degradation reveals BET bromodomains as the cellular target of Hedgehog Pathway Inhibitor-1

Bagka

Choi²,

Héritier

et al. 2022

Preprint

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“…To our knowledge, this is the first study that assesses the contribution of BET proteins and any other epigenetic events on myofibroblast differentiation in an arthrofibrosis‐related model. However, other studies have demonstrated that targeting of BET proteins is anti‐fibrotic in several models of soft tissue fibrosis, including kidney, 48,49 liver, 50,51 skin, 52 and lung 53–55 . The role of epigenetics, including BET proteins, in soft tissue fibrosis has also been extensively summarized in review articles 20,56 .…”

Section: Discussionmentioning

confidence: 99%

The epigenetic regulator BRD4 is required for myofibroblast differentiation of knee fibroblasts

Dudakovic

Bayram

Bettencourt

et al. 2023

J of Cellular Biochemistry

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Arthrofibrosis, which is characterized by excessive scar tissue and limited motion, can complicate the daily functioning of patients after total knee arthroplasty (TKA). Molecular hallmarks of arthrofibrosis include pathologic accumulation of myofibroblasts and disproportionate collagen deposition.Epigenetic mechanisms, including posttranslation modification of histones, control gene expression and may regulate fibrotic events. This study assessed the role of the bromodomain and extra-terminal (BET) proteins on myofibroblast differentiation. This group of epigenetic regulators recognize acetylated lysines and are targeted by a class of drugs known as BET inhibitors. RNA-seq analysis revealed robust mRNA expression of three BET members (BRD2, BRD3, and BRD4) while the fourth member (BRDT) is not expressed in primary TKA knee outgrowth fibroblasts. RT-qPCR and western blot analyses revealed that BET inhibition with the small molecule JQ1 impairs TGFβ1-induced expression of ACTA2, a key myofibroblast marker, in primary outgrowth knee fibroblasts. Similarly, JQ1 administration also reduced COL3A1 mRNA levels and collagen deposition as monitored by picrosirius red staining. Interestingly, the inhibitory effects of JQ1 on ACTA2 mRNA and protein expression, as well as COL3A1 expression and collagen deposition, were paralleled by siRNA-mediated depletion of BRD4. Together, these data reveal that BRD4-mediated epigenetic events support TGFβ1mediated myofibroblast differentiation and collagen deposition as seen in arthrofibrosis. To our knowledge, these are the first studies that assess epigenetic regulators and their downstream events in the context of arthrofibrosis. Future studies may reveal clinical utility for drugs that target epigenetic pathways, specifically BET proteins, in the prevention and treatment of arthrofibrosis.

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“…Our model has features of an IL-4 mediated fibrosis which mainly results as collagen accumulation, but TGF-β mediated fibrosis could also be studied in greater detail including also additional markers such as α-smooth muscle actin [ 35 , 37 ]. In addition, as TRPA1 is highly permeable to calcium and expressed in fibroblasts, it is an interesting hypothesis for future studies if TRPA1-antagonists could alleviate fibrosis by influencing calcium signaling of fibroblasts like some other compounds have been reported to do [ 38 , 39 ]. Intracellular calcium mediated fibrosis induced by activation of TRPA1 in fibroblasts has also been reviewed recently [ 7 ].…”

Section: Discussionmentioning

confidence: 99%

TRPA1 as a potential factor and drug target in scleroderma: dermal fibrosis and alternative macrophage activation are attenuated in TRPA1-deficient mice in bleomycin-induced experimental model of scleroderma

et al. 2023

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Background Systemic sclerosis is a rheumatoid disease best known for its fibrotic skin manifestations called scleroderma. Alternatively activated (M2-type) macrophages are normally involved in the resolution of inflammation and wound healing but also in fibrosing diseases such as scleroderma. TRPA1 is a non-selective cation channel, activation of which causes pain and neurogenic inflammation. In the present study, we investigated the role of TRPA1 in bleomycin-induced skin fibrosis mimicking scleroderma. Methods Wild type and TRPA1-deficient mice were challenged with intradermal bleomycin injections to induce a scleroderma-mimicking disease. Macrophages were investigated in vitro to evaluate the underlying mechanisms. Results Bleomycin induced dermal thickening and collagen accumulation in wild type mice and that was significantly attenuated in TRPA1-deficient animals. Accordingly, the expression of collagens 1A1, 1A2, and 3A1 as well as pro-fibrotic factors TGF-beta, CTGF, fibronectin-1 and YKL-40, and M2 macrophage markers Arg1 and MRC1 were lower in TRPA1-deficient than wild type mice. Furthermore, bleomycin was discovered to significantly enhance M2-marker expression particularly in the presence of IL-4 in wild type macrophages in vitro, but not in macrophages harvested from TRPA1-deficient mice. IL-4-induced PPARγ-expression in macrophages was increased by bleomycin, providing a possible mechanism behind the phenomenon. Conclusions In conclusion, the results indicate that interfering TRPA1 attenuates fibrotic and inflammatory responses in bleomycin-induced scleroderma. Therefore, TRPA1-blocking treatment could potentially alleviate M2 macrophage driven diseases like systemic sclerosis and scleroderma.

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Inhibition of bromodomain extraterminal histone readers alleviates skin fibrosis in experimental models of scleroderma

Cited by 11 publications

References 46 publications

Targeted protein degradation reveals BET bromodomains as the cellular target of Hedgehog Pathway Inhibitor-1

Targeted protein degradation reveals BET bromodomains as the cellular target of Hedgehog Pathway Inhibitor-1

The epigenetic regulator BRD4 is required for myofibroblast differentiation of knee fibroblasts

TRPA1 as a potential factor and drug target in scleroderma: dermal fibrosis and alternative macrophage activation are attenuated in TRPA1-deficient mice in bleomycin-induced experimental model of scleroderma

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