Dissolution and regeneration of starch in hydroxyl-functionalized ionic liquid aqueous solution.

There have been continuous quests for suitable solvents for starch, given the importance of effective starch dissolution in its modification and subsequent materials production. In light of this, the potential of hydroxyl-functionalized ionic liquid (IL) as a promising solvent for starch was investigated. Within this study, a hydroxyl-functionalized IL 1-(2,3-dihydroxypropyl)-3-methylimidazole chloride ([Dhpmim][Cl]) was synthesized, and the dissolution of starch in this IL and its aqueous solutions was examined. Starch (5.35 wt%) was completely dissolved in [Dhpmim][Cl] within 2 h at 100 °C. The solubility of starch in [Dhpmim][Cl]-water mixtures initially increased and then decreased with rising water content. The optimal ratio was found to be 1:9 (wt/wt) water:[Dhpmim][Cl], achieving the highest solubility at 9.28 wt%. Density functional theory (DFT) simulations elucidated the possible interactions between starch and solvents. After dissolution and regeneration in the 1:9 water:[Dhpmim][Cl] mixture, starch showed no discernible change in the molecular structure, with no derivatization reaction observed. Regenerated starch exhibited a transformation in crystalline structure from A-type to V-type, and its relative crystallinity (12.4 %) was lower than that of native starch (25.2 %), resulting in decreased thermal stability. This study suggests that the hydroxyl-functionalized IL, [Dhpmim][Cl], and its aqueous solutions serve as effective solvents for starch dissolution.

Feature learning framework based on EEG graph self-attention networks for motor imagery BCI systems.

Learning distinguishable features from raw EEG signals is crucial for accurate classification of motor imagery (MI) tasks. To incorporate spatial relationships between EEG sources, we developed a feature set based on an EEG graph. In this graph, EEG channels represent the nodes, with power spectral density (PSD) features defining their properties, and the edges preserving the spatial information. We designed an EEG based graph self-attention network (EGSAN) to learn low-dimensional embedding vector for EEG graph, which can be used as distinguishable features for motor imagery task classification. We evaluated our EGSAN model on two publicly available MI EEG datasets, each containing different types of motor imagery tasks. Our experiments demonstrate that our proposed model effectively extracts distinguishable features from EEG graphs, achieving significantly higher classification accuracies than existing state-of-the-art methods.

Neointima abating and endothelium preserving - An adventitia-localized nanoformulation to inhibit the epigenetic writer DOT1L.

Open vascular reconstructions such as bypass are common treatments for cardiovascular disease. Unfortunately, neointimal hyperplasia (IH) follows, leading to treatment failure for which there is no approved therapy. Here we combined the strengths of tailoring nanoplatforms for open vascular reconstructions and targeting new epigenetic mechanisms. We produced adhesive nanoparticles (ahNP) that could be pen-brushed and immobilized on the adventitia to sustainably release pinometostat, an inhibitor drug selective to the epigenetic writer DOT1L that catalyzes histone-3 lysine-79 dimethylation (H3K79me2). This treatment not only reduced IH by 76.8% in injured arteries mimicking open reconstructions in obese Zucker rats with human-like diseases but also avoided the shortcoming of endothelial impairment in IH management. In mechanistic studies, chromatin immunoprecipitation (ChIP) sequencing revealed co-enrichment of the histone mark H3K27ac(acetyl) and its reader BRD4 at the gene of aurora kinase B (AURKB), where H3K79me2 was also enriched as indicated by ChIP-qPCR. Accordingly, DOT1L co-immunoprecipitated with H3K27ac. Furthermore, the known IH driver BRD4 governed the expression of DOT1L which controlled AURKB's protein level, revealing a BRD4- > DOT1L- > AURKB axis. Consistently, AURKB-selective inhibition reduced IH. Thus, this study presents a prototype nanoformulation suited for open vascular reconstructions, and the new insights into chromatin modulators may aid future translational advances.

Targeted PERK inhibition with biomimetic nanoclusters confers preventative and interventional benefits to elastase-induced abdominal aortic aneurysms.

Abdominal aortic aneurysm (AAA) is a progressive aortic dilatation, causing ∼80% mortality upon rupture. Currently, there is no approved drug therapy for AAA. Surgical repairs are invasive and risky and thus not recommended to patients with small AAAs which, however, account for ∼90% of the newly diagnosed cases. It is therefore a compelling unmet clinical need to discover effective non-invasive strategies to prevent or slow down AAA progression. We contend that the first AAA drug therapy will only arise through discoveries of both effective drug targets and innovative delivery methods. There is substantial evidence that degenerative smooth muscle cells (SMCs) orchestrate AAA pathogenesis and progression. In this study, we made an exciting finding that PERK, the endoplasmic reticulum (ER) stress Protein Kinase R-like ER Kinase, is a potent driver of SMC degeneration and hence a potential therapeutic target. Indeed, local knockdown of PERK in elastase-challenged aorta significantly attenuated AAA lesions in vivo. In parallel, we also conceived a biomimetic nanocluster (NC) design uniquely tailored to AAA-targeting drug delivery. This NC demonstrated excellent AAA homing via a platelet-derived biomembrane coating; and when loaded with a selective PERK inhibitor (PERKi, GSK2656157), the NC therapy conferred remarkable benefits in both preventing aneurysm development and halting the progression of pre-existing aneurysmal lesions in two distinct rodent models of AAA. In summary, our current study not only establishes a new intervention target for mitigating SMC degeneration and aneurysmal pathogenesis, but also provides a powerful tool to facilitate the development of effective drug therapy of AAA.

Gene-repressing epigenetic reader EED unexpectedly enhances cyclinD1 gene activation.

Epigenetically switched, proliferative vascular smooth muscle cells (SMCs) form neointima, engendering stenotic diseases. Histone-3 lysine-27 trimethylation (H3K27me3) and acetylation (H3K27ac) marks are associated with gene repression and activation, respectively. The polycomb protein embryonic ectoderm development (EED) reads H3K27me3 and also enhances its deposition, hence is a canonical gene repressor. However, herein we found an unexpected role for EED in activating the bona fide pro-proliferative gene Ccnd1 (cyclinD1). EED overexpression in SMCs increased Ccnd1 mRNA, seemingly contradicting its gene-repressing function. However, consistently, EED co-immunoprecipitated with gene-activating H3K27ac reader BRD4, and they co-occupied at both mitogen-activated Ccnd1 and mitogen-repressed P57 (bona fide anti-proliferative gene), as indicated by chromatin immunoprecipitation qPCR. These results were abolished by an inhibitor of either the EED/H3K27me3 or BRD4/H3K27ac reader function. In accordance, elevating BRD4 increased H3K27me3. In vivo, while EED was upregulated in rat and human neointimal lesions, selective EED inhibition abated angioplasty-induced neointima and reduced cyclinD1 in rat carotid arteries. Thus, results uncover a previously unknown role for EED in Ccnd1 activation, likely via its cooperativity with BRD4 that enhances each other's reader function; i.e., activating pro-proliferative Ccnd1 while repressing anti-proliferative P57. As such, this study confers mechanistic implications for the epigenetic intervention of neointimal pathology.

Fundus-Vascular Responses to Color Deviation Caused by Non-Oxidative Blue Filtering.

Aims: Short-wavelength blue light damaged retina by the oxidative stress in the retinal pigment epithelial (RPE) cells. Filtering blue light from screen could reduce blue hazard, whereas it inevitably altered color-gamut coverage and color-deviation level. Although abnormal fundus-vascular density (FVD) sometimes indicated fundus disease, few researchers noticed its responses to the variation of color-gamut coverage and color-deviation level. Methods: In this study, we performed cellular experiments and analyzed the RPE cell viabilities (CVs) in spectrums with different blue (455-475 nm) ratios to describe the corresponding oxidative-stress levels. Further, we investigated the effects of color-gamut and deviation on FVD variations during the screen-watching task using human factor experiments with 30 participants (university students, including 17 males and 13 females, 21 to 30 years old). Results: RPE CVs were similar in different spectrums, implying that non-oxidative blue filtering hardly contributed to CV improvement. Color-deviation level seems to induce more significant effects on the visual function compared to color-gamut coverage, and MTF and FVD presents similar variation trends during the visual task. Conclusion: Oxidative-free blue filtering contributed little to decrease retinal oxidative stress yet caused color-deviation increase, which caused significant FVD reduction.

Coefficient-of-variation-based channel selection with a new testing framework for MI-based BCI.

In the motor-imagery (MI) based brain computer interface (BCI), multi-channel electroencephalogram (EEG) is often used to ensure the complete capture of physiological phenomena. With the redundant information and noise, EEG signals cannot be easily converted into separable features through feature extraction algorithms. Channel selection algorithms are proposed to address the issue, in which the filtering technique is widely used with the advantages of low computational cost and strong practicability. In this study, we proposed several improved methods for filtering channel selection algorithm. Specifically, based on the coefficient of variation and inter-class distance, a novel channel classification method was designed, which divided channels into different categories based on their contribution to feature extraction process. Then a filtering channel selection algorithm was proposed according to the previous classification method. Moreover, a new testing framework for filtering channel selection algorithms was proposed, which can better reflect the generalization ability of the algorithm. Experimental results indicated that the proposed channel classification method is effective, and the proposed testing framework is better than the original one. Meanwhile, the proposed channel selection algorithm achieved the accuracy of 87.7% and 81.7% in two BCI competition datasets, respectively, which was superior to competing algorithms.

Bispectrum-based hybrid neural network for motor imagery classification.

BACKGROUND: The performance of motor imagery electroencephalogram (MI-EEG) decoding systems is easily affected by noise. As a higher-order spectra (HOS), the bispectrum is capable of suppressing Gaussian noise and increasing the signal-to-noise ratio of signals. However, the sum of logarithmic amplitudes (SLA) and the first order spectral moment (FOSM) features extracted from the bispectrum only use the numerical values of the bispectrum, ignoring the related information between different frequency bins. NEW METHOD: In this study, we proposed a novel framework, termed a bispectrum-based hybrid neural network (BHNN), to make full use of bispectrum for improving the performance of the MI-based brain-computer interface (BCI). Specifically, the BHNN consisted of a convolutional neural network (CNN), gated recurrent units (GRU), and squeeze-and-excitation (SE) modules. The SE modules and CNNs are first used to learn the deep relation between frequency bins of the bispectrum estimated from different time window segmentations of the MI-EEG. Then, we used GRU to seek the overlooked sequential information of the bispectrum. RESULTS: To validate the effectiveness of the proposed BHNN, three public BCI competition datasets were used in this study. The results demonstrated that the BHNN can achieve promising performance in decoding MI-EEG. COMPARISON WITH EXISTING METHODS: The statistical test results demonstrated that the proposed BHNN can significantly outperform other competing methods (p < =0.05). CONCLUSION: The proposed BHNN is a novel bispectrum-based neural network, which can enhance the decoding performance of MI-based BCIs.

SincNet-Based Hybrid Neural Network for Motor Imagery EEG Decoding.

It is difficult to identify optimal cut-off frequencies for filters used with the common spatial pattern (CSP) method in motor imagery (MI)-based brain-computer interfaces (BCIs). Most current studies choose filter cut-frequencies based on experience or intuition, resulting in sub-optimal use of MI-related spectral information in the electroencephalography (EEG). To improve information utilization, we propose a SincNet-based hybrid neural network (SHNN) for MI-based BCIs. First, raw EEG is segmented into different time windows and mapped into the CSP feature space. Then, SincNets are used as filter bank band-pass filters to automatically filter the data. Next, we used squeeze-and-excitation modules to learn a sparse representation of the filtered data. The resulting sparse data were fed into convolutional neural networks to learn deep feature representations. Finally, these deep features were fed into a gated recurrent unit module to seek sequential relations, and a fully connected layer was used for classification. We used the BCI competition IV datasets 2a and 2b to verify the effectiveness of our SHNN method. The mean classification accuracies (kappa values) of our SHNN method are 0.7426 (0.6648) on dataset 2a and 0.8349 (0.6697) on dataset 2b, respectively. The statistical test results demonstrate that our SHNN can significantly outperform other state-of-the-art methods on these datasets.

Multi-view optimization of time-frequency common spatial patterns for brain-computer interfaces.

BACKGROUND: Common spatial pattern (CSP) is a prevalent method applied to feature extraction in motor imagery (MI)-based brain-computer interfaces (BCIs) recorded by electroencephalogram (EEG). The selection of time windows and frequency bands prominently affects the performance of CSP algorithms. Concerning the joint optimization of these two parameters, several studies have utilized a unified framework based on different feature selection strategies and achieved considerable improvement. However, during the feature selection process, useful information could be discarded inevitably and the underlying internal structure of features could be neglected. NEW METHOD: In this paper, we proposed a novel framework termed time window filter bank common spatial pattern with multi-view optimization (TWFBCSP-MVO) to further boost the decoding of MI tasks. Concretely, after extracting CSP features from different time-frequency decompositions of EEG signals, a preliminary screening strategy based on variance ratio was devised to filter out the unrelated spatial patterns. We then introduced a multi-view learning strategy for the simultaneous optimization of time windows and frequency bands. A support vector machine classifier was trained to determine the output of the brain. RESULTS: An experimental study was conducted on two public datasets to verify the effectiveness of TWFBCSP-MVO. Results showed that the proposed TWFBCSP-MVO could help improve the performance of MI classification. COMPARISON WITH EXISTING METHODS: In comparison to other competing methods, the proposed method performed significantly better (p<0.01). CONCLUSIONS: The proposed method is a promising contestant to improve the performance of practical MI-based BCIs.

Biomimetic, ROS-detonable nanoclusters - A multimodal nanoplatform for anti-restenotic therapy.

The long-term success of endovascular intervention has long been overshadowed by vessel re-occlusion, also known as restenosis. Mainstream anti-restenotic devices, such as drug-eluting stent (DES) and drug-coated balloon (DCB), were recently shown with suboptimal performances and life-threatening complications, thereby underpinning the urgent need for alternative strategies with enhanced efficacy and safety profile. In our current study, we engineered a multimodal nanocluster formed by self-assembly of unimolecular nanoparticles and surface coated with platelet membrane, specifically tailored for precision drug delivery in endovascular applications. More specifically, it incorporates the combined merits of platelet membrane coating (lesion targetability and biocompatibility), reactive oxygen species (ROS)-detonable "cluster-bomb" chemistry (to trigger the large-to-small size transition at the target site, thereby achieving longer circulation time and higher tissue penetration), and sustained drug release. Using RVX-208 (an emerging anti-restenotic drug under clinical trials) as the model payload, we demonstrated the superior performances of our nanocluster over conventional poly(lactic-co-glycolic acid) (PLGA) nanoparticle. In cultured vascular smooth muscle cell (VSMC), the drug-loaded nanocluster induced effective inhibition of proliferation and protective gene expression (e.g., APOA-I) with a significantly reduced dosage of RVX-208 (1 µM). In a rat model of balloon angioplasty, intravenous injection of Cy5.5-tagged nanocluster led to greater lesion targetability, improved biodistribution, and deeper penetration into injured vessel walls featuring enriched ROS. Moreover, in contrast to either free drug solution or drug-loaded PLGA nanoparticle formulation, a single injection with the drug-loaded nanocluster (10 mg/kg of RVX-208) was sufficient to substantially mitigate restenosis. Additionally, this nanocluster also demonstrated biocompatibility according to in vitro cytotoxicity assay and in vivo histological and tissue qPCR analysis. Overall, our multimodal nanocluster offers improved targetability, tissue penetration, and ROS-responsive release over conventional nanoparticles, therefore making it a highly promising platform for development of next-generation endovascular therapies.

Comparison of linear and nonlinear function to describe and predict componential evolution of biomass pyrolysis vapors during condensation in a tubular indirect heat exchanger.

A novel experimental method based on the combination of bio-oil composition inversion and function fitting was purposed and verified for describing the componential evolution curves during the liquefaction of biomass pyrolysis vapors. The evolution curves of representative condensable components were fitted by linear and Slogistic function in the short, middle and long three condensing fields. Linear function exhibited a significant effectiveness for the description and prediction of low-boiling water and furfural and the relative deviations were no more than 5% between actual values in long condenser and predictive values from the elongation of curves in short and middle condensers. For high-boiling phenolic compounds, linear function failed to fit their evolutions in long condenser but Slogistic fitting remained effective despite the relative deviation increasing to about 10%. This investigation provided a unique and effective prediction method for the vapor evolution in industrial shell and tube heat exchanger according to laboratory-scale experiment.

An adventitial painting modality of local drug delivery to abate intimal hyperplasia.

A major medical problem is the persistent lack of approved therapeutic methods to prevent postoperative intimal hyperplasia (IH) which leads to high-rate failure of open vascular reconstructions such as bypass grafting. Hydrogel has been widely used in preclinical trials for perivascular drug administration to mitigate postoperative IH. However, bulky hydrogel is potentially pro-inflammatory, posing a significant hurdle to clinical translation. Here we developed a new modality of directly "painting" drug-loaded unimolecular micelles (UM) to the adventitia thus obviating the need for a hydrogel. To render tissue adhesion, we generated amine-reactive unimolecular micelles with N-hydroxysuccinimide ester (UM-NHS) terminal groups to form stable amide bonds with the adventitia. To test periadventitial application, we either soaked balloon-injured rat carotid arteries in crosslinked UM-NHS (Mode-1) or non-crosslinked UM-NHS (Mode-2), or painted the vessel surface with non-crosslinked UM-NHS (Mode-3). The UM-NHS were loaded with or without a model drug (rapamycin) known to be IH inhibitory. We found that Mode-1 produced a marked IH-mitigating drug effect but also caused severe tissue damage. Mode-2 resulted in lower tissue toxicity yet less drug effect on IH. However, the painting method, Mode-3, demonstrated a pronounced therapeutic effect (75% inhibition of IH) without obvious toxicity. In summary, we present a simple painting modality of periadventitial local drug delivery using tissue-adhesive UM. Given the robust IH-abating efficacy and low tissue toxicity, this prototype merits further development towards an effective anti-stenosis therapy suitable for open vascular reconstructions.

A Role for Polo-Like Kinase 4 in Vascular Fibroblast Cell-Type Transition.

Polo-like kinase 4 (PLK4) is canonically known for its cytoplasmic function in centriole duplication. Here we show a noncanonical PLK4 function of regulating the transcription factor SRF's nuclear activity and associated myofibroblast-like cell-type transition. In this context, we have further found that PLK4's phosphorylation and transcription are respectively regulated by PDGF receptor and epigenetic factor BRD4. Furthermore, in vivo experiments suggest PLK4 inhibition as a potential approach to mitigating vascular fibrosis.

A hierarchical and collaborative BRD4/CEBPD partnership governs vascular smooth muscle cell inflammation.

Bromodomain protein BRD4 reads histone acetylation (H3K27ac), an epigenomic mark of transcription enhancers. CCAAT enhancer binding protein delta (CEBPD) is a transcription factor typically studied in metabolism. While both are potent effectors and potential therapeutic targets, their relationship was previously unknown. Here we investigated their interplay in vascular smooth muscle cell (SMC) inflammation. Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) revealed H3K27ac/BRD4 enrichment at Cebpd in injured rat carotid arteries. While genomic deletion of BRD4-associated enhancer in SMCs in vitro decreased Cebpd transcripts, BRD4 gene silencing also diminished Cebpd mRNA and protein, indicative of a BRD4 control over CEBPD expression. Bromodomain-1, but not bromodomain-2, accounted for this BRD4 function. Moreover, endogenous BRD4 protein co-immunoprecipitated with CEBPD, and both proteins co-immunoprecipitated the Cebpd promoter and enhancer DNA fragments. These co-immunoprecipitations (coIPs) were all abolished by the BRD4-bromodomain blocker JQ1, suggesting a BRD4/CEBPD /promoter/enhancer complex. While BRD4 and CEBPD were both upregulated upon tumor necrosis factor alpha (TNF-α) stimulation of SMC inflammation (increased interleukin [IL]-1b, IL-6, and MCP-1), they mediated this stimulation via preferentially elevated expression of platelet-derived growth factor receptor alpha (PDGFRα, versus PDGFRß), as indicated by loss- and gain-of-function experiments. Taken together, our study unravels a hierarchical yet collaborative BRD4/CEBPD relationship, a previously unrecognized mechanism that prompts SMC inflammation and may underlie other pathophysiological processes as well.

Nullifying epigenetic writer DOT1L attenuates neointimal hyperplasia.

BACKGROUND AND AIMS: Histone methyltransferases are emerging targets for epigenetic therapy. DOT1L (disruptor of telomeric silencing 1-like) is the only known methylation writer at histone 3 lysine 79 (H3K79). It is little explored for intervention of cardiovascular disease. We investigated the role of DOT1L in neointimal hyperplasia (IH), a basic etiology of occlusive vascular diseases. METHODS AND RESULTS: IH was induced via balloon angioplasty in rat carotid arteries. DOT1L and its catalytic products H3K79me2 and H3K79me3 (immunostaining) increased by 4.69 ± 0.34, 2.38 ± 0.052, and 3.07 ± 0.27 fold, respectively, in injured (versus uninjured) carotid arteries at post-injury day 7. Dot1l silencing via shRNA-lentivirus infusion in injured arteries reduced DOT1L, H3K79me2, and IH at day 14 by 54.5%, 37.1%, and 76.5%, respectively. Moreover, perivascular administration of a DOT1L-selective inhibitor (EPZ5676) reduced H3K79me2, H3K79me3, and IH by 56.1%, 58.6%, and 39.9%, respectively. In addition, Dot1l silencing and its inhibition (with EPZ5676) in vivo in injured arteries boosted smooth muscle α-actin immunostaining; pretreatment of smooth muscle cells with EPZ5676 in vitro reduced pro-proliferative marker proteins, including proliferating cell nuclear antigen (PCNA) and cyclin-D1. CONCLUSIONS: While DOT1L is upregulated in angioplasty-injured rat carotid arteries, either its genetic silencing or pharmacological inhibition diminishes injury-induced IH. As such, this study presents a strong rationale for continued mechanistic and translational investigation into DOT1L targeting for treatment of (re)stenotic vascular conditions.

PERK Inhibition Mitigates Restenosis and Thrombosis: A Potential Low-Thrombogenic Antirestenotic Paradigm.

Developing endothelial-protective, nonthrombogenic antirestenotic treatments has been a challenge. A major hurdle to this has been the identification of a common molecular target in both smooth muscle cells and endothelial cells, inhibition of which blocks dysfunction of both cell types. The authors' findings suggest that the PERK kinase could be such a target. Importantly, PERK inhibition mitigated both restenosis and thrombosis in preclinical models, implicating a low-thrombogenic antirestenotic paradigm.

An air-stable anionic two-dimensional semiconducting metal-thiolate network and its exfoliation into ultrathin few-layer nanosheets.

The black, small-bandgap semiconducting framework Eu-dfdmat features extensive Eu3+-sulfur bridges from the linear linker 2,5-difluoro-3,6-dimercaptoterephthalate (dfdmt). Each Eu center is chelated to four dfdmt linkers to form an anionic coordination sphere involving four carboxyl O and four mercapto S centers (EuO4S4), wherein the charge buildup can be alleviated by the electron-withdrawing fluoro groups. The extensive metal-linker bonding, together with a trace of Eu2+ species, appears to boost electronic interaction in the 2D net, generating a small band gap of 1.31 eV (946 nm), albeit a modest conductivity (e.g., 10-6 S m-1). The crystals also exhibit persistent EPR signals indicative of organic radicals (g = 2.002). The Eu-dfdmt solid are stable in air and can be exfoliated into ultrathin nanosheets (ca. 5 nm; 6-8 layers).

The BD2 domain of BRD4 is a determinant in EndoMT and vein graft neointima formation.

BACKGROUND: Vein-graft bypass is commonly performed to overcome atherosclerosis but is limited by high failure rates, principally due to neointimal wall thickening. Recent studies reveal that endothelial-mesenchymal transition (EndoMT) is critical for vein-graft neointima formation. BETs are a family of Bromo/ExtraTerminal domains-containing epigenetic reader proteins (BRD2, BRD3, BRD4). They bind acetylated histones through their unique tandem bromodomains (BD1, BD2), facilitating transcriptional complex formation and cell-state transitions. The role for BETs, including individual BRDs and their unique BDs, is not well understood in EndoMT and neointimal formation. METHODS AND RESULTS: Repression of BRD4 expression abrogated TGFß1-induced EndoMT, with greater effects than BRD2 or BRD3 knockdown. An inhibitor selective for BD2 in all BETs, but not that for BD1, blocked EndoMT. Moreover, expression of a dominant-negative BRD4-specific BD2 fully abolished EndoMT. Concordantly, BRD4 knockdown repressed TGFß1-stimulated increase of ZEB1 protein - a transcription factor integral in EndoMT. In vivo, lentiviral gene transfer of either BRD4 shRNA or dominant negative BRD4-specific BD2 mitigated neointimal development in rat jugular veins grafted to carotid arteries. CONCLUSIONS: Our data reveal the BD2 domain of BRD4 as a determinant driving EndoMT in vitro and neointimal formation in vivo. These findings provide new insight into BET biology, while offering prospects of specific BET domain targeting as an approach to limiting neointima and extending vein graft patency.

HDAC6 Regulates the MRTF-A/SRF Axis and Vascular Smooth Muscle Cell Plasticity.

Cellular plasticity is fundamental in biology and disease. Vascular smooth muscle cell (SMC) dedifferentiation (loss of contractile proteins) initiates and perpetrates vascular pathologies such as restenosis. Contractile gene expression is governed by the master transcription factor, serum response factor (SRF). Unlike other histone deacetylases, histone deacetylase 6 (HDAC6) primarily resides in the cytosol. Whether HDAC6 regulates SRF nuclear activity was previously unknown in any cell type. This study found that selective inhibition of HDAC6 with tubastatin A preserved the contractile protein (alpha-smooth muscle actin) that was otherwise diminished by platelet-derived growth factor-BB. Tubastatin A also enhanced SRF transcriptional (luciferase) activity, and this effect was confirmed by HDAC6 knockdown. Interestingly, HDAC6 inhibition increased acetylation and total protein of myocardin-related transcription factor A (MRTF-A), a transcription co-activator known to translocate from the cytosol to the nucleus, thereby activating SRF. Consistently, HDAC6 co-immunoprecipitated with MRTF-A. In vivo studies showed that tubastatin A treatment of injured rat carotid arteries mitigated neointimal lesion, which is known to be formed largely by dedifferentiated SMCs. This report is the first to show HDAC6 regulation of the MRTF-A/SRF axis and SMC plasticity, thus opening a new perspective for interventions of vascular pathologies.