Targeting bromodomain-containing proteins to prevent spontaneous preterm birth

Investigation of the impact of bromodomain inhibition on cytoskeleton stability and contraction

BACKGROUND

Injury to contractile organs such as the heart, vasculature, urinary bladder and gut can stimulate a pathological response that results in loss of normal contractility. PDGF and TGFβ are among the most well studied initiators of the injury response and have been shown to induce aberrant contraction in mechanically active cells of hollow organs including smooth muscle cells (SMC) and fibroblasts. However, the mechanisms driving contractile alterations downstream of PDGF and TGFβ in SMC and fibroblasts are incompletely understood, limiting therapeutic interventions.

METHODS

To identify potential molecular targets, we have leveraged the analysis of publicly available data, comparing transcriptomic changes in mechanically active cells stimulated with PDGF and TGFβ. Additional Analysis of publicly available data sets were performed on SMC and fibroblasts treated in the presence or absence of the MYC inhibitor JQ1. Validation of in silico findings were performed with qPCR, immunoblots, and collagen gel contraction assays measure the effect of JQ1 on cytoskeleton associated genes, proteins and contractility in mechanically active cells. Likelihood ratio test and FDR adjusted p-values were used to determine significant differentially expressed genes. Student ttest were used to calculate statistical significance of qPCR and contractility analyses.

RESULTS

Comparing PDGF and TGFβ stimulated SMC and fibroblasts identified a shared molecular profile regulated by MYC and members of the AP-1 transcription factor complex. Additional in silico analysis revealed a unique set of cytoskeleton-associated genes that were sensitive to MYC inhibition with JQ1. In vitro validation demonstrated JQ1 was also able to attenuate TGFβ and PDGF induced changes to the cytoskeleton and contraction of smooth muscle cells and fibroblasts in vitro.

CONCLUSIONS

These findings identify MYC as a key driver of aberrant cytoskeletal and contractile changes in fibroblasts and SMC, and suggest that JQ1 could be used to restore normal contractile function in hollow organs.

Investigating the expression of fertility-regulating LncRNAs in multiparous and uniparous Shal ewe's ovaries

Sheep is the primary source of animal protein in Iran. Birth type is one of the significant features that determine total meat output. Little is known about how long non-coding RNAs (LncRNAs) affect litter size. The purpose of this research is to investigate the DE-LncRNAs in ovarian tissue between multiparous and uniparous Shal ewes. Through bioinformatics analyses, LncRNAs with variable expression levels between ewes were discovered. Target genes were annotated using the DAVID database, and STRING and Cytoscape software were used to evaluate their interactions. The expression levels of 148 LncRNAs were different in the multiparous and uniparous ewe groups (false discovery rate (FDR) < 0.05). Eight biological process terms, nine cellular component terms, 10 molecular function terms, and 38 KEGG pathways were significant (FDR < 0.05) in the GO analysis. One of the most significant processes impacting fertility is mitogen-activated protein kinase (MAPK) signaling pathway, followed by oocyte meiosis, gonadotropin-releasing hormone signaling pathway, progesterone-mediated oocyte maturation, oxytocin signaling pathway, and cAMP signaling pathway. ENSOARG00000025710, ENSOARG00000025667, ENSOARG00000026034, and ENSOARG00000026632 are LncRNAs that may affect litter size and fertility. The most crucial hub genes include MAPK1, BRD2, GAK, RAP1B, FGF2, RAP1B, and RAP1B. We hope that this study will encourage researchers to further investigate the effect of LncRNAs on fertility.

Investigation of the impact of bromodomain inhibition on cytoskeleton stability and contraction

Injury to contractile organs such as the heart, vasculature, urinary bladder and gut can stimulate a pathological response that results in loss of normal contractility. PDGF and TGFβ are among the most well studied initiators of the injury response and have been shown to induce aberrant contraction in mechanically active cells of hollow organs including smooth muscle cells (SMC) and fibroblasts. However the mechanisms driving contractile alterations downstream of PDGF and TGFβ in SMC and fibroblasts are incompletely understood, limiting therapeutic interventions. To identify potential molecular targets, we have leveraged the analysis of publicly available data, comparing transcriptomic changes in mechanically active cells stimulated with PDGF and TGFβ and identified a shared molecular profile regulated by MYC and members of the AP-1 transcription factor complex. We also analyzed data sets from SMC and fibroblasts treated in the presence or absence of the MYC inhibitor JQ1. This analysis revealed a unique set of cytoskeleton-associated genes that were sensitive to MYC inhibition. JQ1 was also able to attenuate TGFβ and PDGF induced changes to the cytoskeleton and contraction of smooth muscle cells and fibroblasts in vitro. These findings identify MYC as a key driver of aberrant cytoskeletal and contractile changes in fibroblasts and SMC, and suggest that JQ1 could be used to restore normal contractile function in hollow organs.

Regulation of inflammatory genes in decidual cells: Involvement of the bromodomain and extra-terminal family proteins

The decidua undergoes proinflammatory activation in late pregnancy, promoting labor. Bromodomain and Extra-Terminal (BET) family proteins interact with acetylated histones and may control gene expression in inflammation. Here, we assessed whether BETs are involved in inflammatory gene regulation in human decidual cells. We have treated primary cultures of decidual stromal cells (DSCs) from term pregnancies with endotoxin (LPS) and measured the expression of a panel of pro-and anti-inflammatory genes. BET involvement was assessed using the selective BET inhibitors (+)-JQ1 and I-BET-762 or the negative control compound (-)-JQ1. Histone 3 and -4 acetylation and BETs binding at the target gene promoters were determined to assess whether these processes are involved in the actions of LPS, BETs, and BET inhibitors. LPS increased the expression of the proinflammatory (PTGS2, IL6, CXCL8/IL8, TNF) and the anti-inflammatory (IL10, IDO1) genes of the panel. The constitutively expressed inflammatory genes (PTGS1, PTGES) were unaffected. The BET inhibitors, but not the control compound, reduced the basal and LPS-induced expression of PTGS1, PTGS2, IL6, CXCL8/IL8, IL10, and IDO1. TNF expression was not changed by BET inhibition. The dominant BETs were Bromodomain-containing protein -2 (BRD2) and -4L (BRD4L) in DSCs. LPS increased histone 4 acetylation at the CXCL8/IL8 and TNF promoters and histone 3 and -4 acetylation at the IDO1 promoter, while (+)-JQ1 abrogated histone acetylation at several promoters. Overall, histone acetylation and promoter binding of BETs showed no consistent relationship with gene expression across the gene panel and the treatments. BET proteins, predominantly BRD2 and BRD4L, control critical pro- and anti-inflammatory genes in DSCs. TNF induction exemplifies a BET-independent pathway. Changing histone acetylation at the promoters is not a general obligatory requirement for inflammatory gene expression in response to LPS. BETs likely act at chromatin loci separate from the examined promoters. BET inhibitors may block decidual activation at labor.

Identification of potential therapeutic intervening targets by in-silico analysis of nsSNPs in preterm birth-related genes

Prematurity is the foremost cause of death in children under 5 years of age. Genetics contributes to 25-40% of all preterm births (PTB) yet we still need to identify specific targets for intervention based on genetic pathways. This study involved the effect of region-specific non-synonymous variations and their transcript level mutational impact on protein functioning and stability by various in-silico tools. This investigation identifies potential therapeutic targets to manage the challenge of PTB, corresponding protein cavities and explores their binding interactions with intervening compounds. We searched 20 genes coding 55 PTB proteins from NCBI. Single Nucleotide Polymorphisms (SNPs) of concerned genes were extracted from ENSEMBL, and filtration of exonic variants (non-synonymous) was performed. Several in-silico downstream protein functional effect prediction tools were used to identify damaging variants. Rare coding variants were selected with an allele frequency of ≤1% in 1KGD, further supported by South Asian ALFA frequencies and GTEx gene/tissue expression database. CNN1, COL24A1, IQGAP2 and SLIT2 were identified with 7 rare pathogenic variants found in 17 transcript sequences. The functional impact analyses of rs532147352 (R>H) of CNN1 computed through PhD-SNP, PROVEAN, SNP&GO, PMut and MutPred2 algorithms showed impending deleterious effects, and the presence of this pathogenic mutation in CNN1 resulted in large decrease in protein structural stability (ΔΔG (kcal/mol). After structural protein identification, homology modelling of CNN1, which has been previously reported as a biomarker for the prediction of PTB, was performed, followed by the stereochemical quality checks of the 3D model. Blind docking approach were used to search the binding cavities and molecular interactions with progesterone, ranked with energetic estimations. Molecular interactions of CNN1 with progesterone were investigated through LigPlot 2D. Further, molecular docking experimentation of CNN1 showed the significant interactions at S102, L105, A106, K123, Y124 with five selected PTB-drugs, Allylestrenol (-7.56 kcal/mol), Hydroxyprogesterone caproate (-8.19 kcal/mol), Retosiban (-9.43 kcal/mol), Ritodrine (-7.39 kcal/mol) and Terbutaline (-6.87 kcal/mol). Calponin-1 gene and its molecular interaction analysis could serve as an intervention target for the prevention of PTB.

A novel oncogenic seRNA promotes nasopharyngeal carcinoma metastasis

Nasopharyngeal carcinoma (NPC) is a common malignant cancer in southern China that has highly invasive and metastatic features and causes high mortality, but the underlying mechanisms of this malignancy remain unclear. In this study, we utilized ChIP-Seq to identify metastasis-specific super enhancers (SEs) and found that the SE of LOC100506178 existed only in metastatic NPC cells and powerfully aggravated NPC metastasis. This metastatic SE transcribed into lncRNA LOC100506178, and it was verified as a seRNA through GRO-Seq. Furthermore, SE-derived seRNA LOC100506178 was found to be highly expressed in metastatic NPC cells and NPC lymph node metastatic tissues. Knockdown of seRNA LOC100506178 arrested the invasion and metastasis of NPC cells in vitro and in vivo, demonstrating that seRNA LOC100506178 accelerates the acquisition of NPC malignant phenotype. Mechanistic studies revealed that seRNA LOC100506178 specifically interacted with the transcription factor hnRNPK and modulated the expression of hnRNPK. Further, hnRNPK in combination with the promoter region of MICAL2 increased Mical2 transcription. Knockdown of seRNA LOC100506178 or hnRNPK markedly repressed MICAL2, Vimentin and Snail expression and upregulated E-cadherin expression. Overexpression of seRNA LOC100506178 or hnRNPK markedly increased MICAL2, Vimentin and Snail expression and decreased E-cadherin expression. Therefore, seRNA LOC100506178 may promote MICAL2 expression by upregulating hnRNPK, subsequently enhancing EMT process and accelerating the invasion and metastasis of NPC cells. seRNA LOC100506178 has the potential to serve as a novel prognostic biomarker and therapeutic target in NPC patients.

BET Proteins Regulate Expression of Osr1 in Early Kidney Development

In utero renal development is subject to maternal metabolic and environmental influences affecting long-term renal function and the risk of developing chronic kidney failure and cardiovascular disease. Epigenetic processes have been implicated in the orchestration of renal development and prenatal programming of nephron number. However, the role of many epigenetic modifiers for kidney development is still unclear. Bromodomain and extra-terminal domain (BET) proteins act as histone acetylation reader molecules and promote gene transcription. BET family members Brd2, Brd3 and Brd4 are expressed in the nephrogenic zone during kidney development. Here, the effect of the BET inhibitor JQ1 on renal development is evaluated. Inhibition of BET proteins via JQ1 leads to reduced growth of metanephric kidney cultures, loss of the nephron progenitor cell population, and premature and disturbed nephron differentiation. Gene expression of key nephron progenitor transcription factor Osr1 is downregulated after 24 h BET inhibition, while Lhx1 and Pax8 expression is increased. Mining of BRD4 ChIP-seq and gene expression data identify Osr1 as a key factor regulated by BRD4-controlled gene activation. Inhibition of BRD4 by BET inhibitor JQ1 leads to downregulation of Osr1, thereby causing a disturbance in the balance of nephron progenitor cell self-renewal and premature differentiation of the nephron, which ultimately leads to kidney hypoplasia and disturbed nephron development. This raises questions about the potential teratogenic effects of BET inhibitors for embryonic development. In summary, our work highlights the role of BET proteins for prenatal programming of nephrogenesis and identifies Osr1 as a potential target of BET proteins.

Oocyte Meiotic Competence in the Domestic Cat Model: Novel Roles for Nuclear Proteins BRD2 and NPM1

To participate in fertilization and embryo development, oocytes stored within the mammalian female ovary must resume meiosis as they are arrested in meiotic prophase I. This ability to resume meiosis, known as meiotic competence, requires the tight regulation of cellular metabolism and chromatin configuration. Previously, we identified nuclear proteins associated with the transition from the pre-antral to the antral follicular stage, the time at which oocytes gain meiotic competence. In this study, the objective was to specifically investigate three candidate nuclear factors: bromodomain containing protein 2 (BRD2), nucleophosmin 1 (NPM1), and asparaginase-like 1 (ASRGL1). Although these three factors have been implicated with folliculogenesis or reproductive pathologies, their requirement during oocyte maturation is unproven in any system. Experiments were conducted using different stages of oocytes isolated from adult cat ovaries. The presence of candidate factors in developing oocytes was confirmed by immunostaining. While BRD2 and ASRGL1 protein increased between pre-antral and the antral stages, changes in NPM1 protein levels between stages were not observed. Using protein inhibition experiments, we found that most BRD2 or NPM1-inhibited oocytes were incapable of participating in fertilization or embryo development. Further exploration revealed that inhibition of BRD2 and NPM-1 in cumulus-oocyte-complexes prevented oocytes from maturing to the metaphase II stage. Rather, they remained at the germinal vesicle stage or arrested shortly after meiotic resumption. We therefore have identified novel factors playing critical roles in domestic cat oocyte meiotic competence. The identification of these factors will contribute to improvement of domestic cat assisted reproduction and could serve as biomarkers of meiotically competent oocytes in other species.

The BET family in immunity and disease

Innate immunity serves as the rapid and first-line defense against invading pathogens, and this process can be regulated at various levels, including epigenetic mechanisms. The bromodomain and extraterminal domain (BET) family of proteins consists of four conserved mammalian members (BRD2, BRD3, BRD4, and BRDT) that regulate the expression of many immunity-associated genes and pathways. In particular, in response to infection and sterile inflammation, abnormally expressed or dysfunctional BETs are involved in the activation of pattern recognition receptor (e.g., TLR, NLR, and CGAS) pathways, thereby linking chromatin machinery to innate immunity under disease or pathological conditions. Mechanistically, the BET family controls the transcription of a wide range of proinflammatory and immunoregulatory genes by recognizing acetylated histones (mainly H3 and H4) and recruiting transcription factors (e.g., RELA) and transcription elongation complex (e.g., P-TEFb) to the chromatin, thereby promoting the phosphorylation of RNA polymerase II and subsequent transcription initiation and elongation. This review covers the accumulating data about the roles of the BET family in innate immunity, and discusses the attractive prospect of manipulating the BET family as a new treatment for disease.

Evaluation of BRD4 levels in patients with early-onset preeclampsia

OBJECTIVE

This study aimed to detect Bromodomain Containing Protein 4 (BRD4) concentrations in the serum of early-onset preeclamptic patients and compare them with the healthy control group.

MATERIAL AND METHODS

This prospective case-control study was performed from June 2019 to December 2019. Of the 80 pregnant patients included in the study, we enrolled 40 patients with early-onset preeclampsia as the study group, and 40 normotensive healthy gestational age- and gravidity-matched patients with normal blood pressure without proteinuria as the control group. Demographic characteristics, amount of proteinuria, and serum BRD4 concentrations were recorded.

RESULTS

Maternal serum BRD4 concentrations were significantly higher in patients with preeclampsia (39.10 ± 42.14 ng/mL) compared to the participants in the control group (13.64 ± 7.24 ng/mL, p < 0.001). There was a positive intermediate correlation between serum BRD4 levels and the amount of proteinuria (r = 0.447, p = 0.006).

CONCLUSION

Maternal serum BRD4 levels were significantly higher in preeclamptic patients compared to healthy pregnant women. Also, the amount of proteinuria was positively correlated with serum BRD4 levels. Although this preliminary study shows increased BRD4 levels in preeclampsia, its utility as a biomarker must be clarified.

Nobiletin exerts anti-diabetic and anti-inflammatory effects in an in vitro human model and in vivo murine model of gestational diabetes

Gestational diabetes mellitus (GDM) is a global health issue, whereby pregnant women are afflicted with carbohydrate intolerance with first onset during pregnancy. GDM is characterized by maternal peripheral insulin resistance, thought to be driven by low-grade maternal inflammation. Nobiletin, a polymethoxylated flavonoid, possesses potent glucose-sensitizing and anti-inflammatory properties; however, its effects in GDM have not been assessed. The present study aimed to determine the effects of nobiletin on glucose metabolism and inflammation associated with GDM in both in vitro human tissues and an in vivo animal model of GDM. In vitro, treatment with nobiletin significantly improved TNF-impaired glucose uptake in human skeletal muscle, and suppressed mRNA expression and protein secretion of pro-inflammatory cytokines and chemokines in human placenta and visceral adipose tissue (VAT). Mechanistically, nobiletin significantly inhibited Akt and Erk activation in placenta, and NF-κB activation in VAT. In vivo, GDM mice treated with 50 mg/kg nobiletin daily via oral gavage from gestational day (gd) 1-17 or via i.p. injections from gd 10-17 significantly improved glucose tolerance. Pregnant GDM mice treated with nobiletin from either gd 1-17 or gd 10-17 exhibited significantly suppressed mRNA expression of pro-inflammatory cytokines and chemokines in placenta, VAT and subcutaneous adipose tissue (SAT). Using a quantitative mass spectrometry approach, we identified differentially abundant proteins associated with the effect of nobiletin in vivo. Together, these studies demonstrate that nobiletin improves glucose metabolism and reduces inflammation associated with GDM and may be a novel therapeutic for the prevention of GDM.

MiR-101-containing extracellular vesicles bind to BRD4 and enhance proliferation and migration of trophoblasts in preeclampsia

Background

Preeclampsia (PE) is a frequently occurring pregnancy disorder in the placenta, which results in various maternal and fetal complications. The current study aims to evaluate the role of extracellular vesicles (EVs)-encapsulated microRNA (miR)-101 in biological processes of trophoblasts in PE and its underlying mechanism.

Methods

Human umbilical cord mesenchymal stem cell (HUCMSC) and HUCMSC-derived EVs were isolated and cultured, after which EV characterization was carried out using PKH67 staining. In silico analyses were adopted to predict the downstream target genes of miR-101, and dual luciferase reporter gene assay was applied to validate the binding affinity. Furthermore, loss- and gain-of-function approaches were adopted to determine the role of miR-101 and bromodomain-containing protein 4 (BRD4) in trophoblast proliferation and invasion using EDU staining and transwell assay. In addition, a rat model of PE was established to verify the function of EV-encapsulated miR-101 in vivo.

Results

Placental tissues obtained from PE patients presented with downregulated miR-101 expression and upregulated BRD4 and CXCL11 expression. EV-encapsulated miR-101 from HUCMSCs could be delivered into the trophoblast HTR-8/SVneo cells, thus enhancing proliferation and migration of trophoblasts. Mechanically, miR-101 targeted and negatively regulated BRD4 expression. BRD4 knockdown promoted the proliferation and migration of trophoblasts by suppressing NF-κB/CXCL11 axis. EV-encapsulated miR-101 from HUCMSCs also reduced blood pressure and 24 h urine protein in vivo, thereby ameliorating PE.

Conclusion

In summary, EV-encapsulated miR-101 promoted proliferation and migration of placental trophoblasts through the inhibition of BRD4 expression via NF-κB/CXCL11 inactivation.