MED1 Regulates BMP/TGF-ß in Endothelium: Implication for Pulmonary Hypertension.

BACKGROUND: Dysregulated BMP (bone morphogenetic protein) or TGF-ß (transforming growth factor beta) signaling pathways are imperative in idiopathic and familial pulmonary arterial hypertension (PAH) as well as experimental pulmonary hypertension (PH) in rodent models. MED1 (mediator complex subunit 1) is a key transcriptional co-activator and KLF4 (Krüppel-like factor 4) is a master transcription factor in endothelium. However, MED1 and KLF4 epigenetic and transcriptional regulations of the BMP/TGF-ß axes in pulmonary endothelium and their dysregulations leading to PAH remain elusive. We investigate the MED1/KLF4 co-regulation of the BMP/TGF-ß axes in endothelium by studying the epigenetic regulation of BMPR2 (BMP receptor type II), ETS-related gene (ERG), and TGFBR2 (TGF-ß receptor 2) and their involvement in the PH. METHODS: High-throughput screening involving data from RNA-seq, MED1 ChIP-seq, H3K27ac ChIP-seq, ATAC-seq, and high-throughput chromosome conformation capture together with in silico computations were used to explore the epigenetic and transcriptional regulation of BMPR2, ERG, and TGFBR2 by MED1 and KLF4. In vitro experiments with cultured pulmonary arterial endothelial cells (ECs) and bulk assays were used to validate results from these in silico analyses. Lung tissue from patients with idiopathic PAH, animals with experimental PH, and mice with endothelial ablation of MED1 (EC-MED1-/-) were used to study the PH-protective effect of MED1. RESULTS: Levels of MED1 were decreased in lung tissue or pulmonary arterial endothelial cells from idiopathic PAH patients and rodent PH models. Mechanistically, MED1 acted synergistically with KLF4 to transactivate BMPR2, ERG, and TGFBR2 via chromatin remodeling and enhancer-promoter interactions. EC-MED1-/- mice showed PH susceptibility. In contrast, MED1 overexpression mitigated the PH phenotype in rodents. CONCLUSIONS: A homeostatic regulation of BMPR2, ERG, and TGFBR2 in ECs by MED1 synergistic with KLF4 is essential for the normal function of the pulmonary endothelium. Dysregulation of MED1 and the resulting impairment of the BMP/TGF-ß signaling is implicated in the disease progression of PAH in humans and PH in rodent models.

Transverse and longitudinal coupling of LSPPs in isolated triangular Al-SiO2-Al hybrid nanoplates for generation of local electromagnetic fields with enhanced intensity and increased decay time.

Achieving a large enhancement of local electromagnetic fields in the ultraviolet waveband is desirable for some applications such as surface-enhanced Raman scattering and surface-enhanced fluorescence. In addition, it is more significant for some applications such as plasmon-enhanced harmonic generation to enhance the intensity of local electromagnetic fields and increase their decay time at the same time. In this paper, using the finite-difference time-domain method, we numerically demonstrate that using the linearly polarized light with a wavelength of 325 nm as the illumination light, an isolated triangular Al-SiO2-Al hybrid nanoplate with optimized geometric parameters can produce a local electric field enhanced by a factor of about 108 at one of its top apexes, and produce two local electric fields enhanced by a factor of about 150 at two transverse dielectric/metal interfaces of one of its longitudinal side edges. Moreover, we also numerically demonstrate that the decay time of enhanced local electric fields produced by the isolated triangular Al-SiO2-Al hybrid nanoplate is about 1.6 times as large as that of enhanced local electric fields produced by an isolated triangular Al nanoplate. These unique properties of the isolated triangular Al-SiO2-Al hybrid nanoplate arise because of both the transverse coupling and the longitudinal coupling of localized surface plasmon polaritons in this structure. Our findings make triangular Al-SiO2-Al hybrid nanoplates very promising for application in many fields such as surface-enhanced Raman scattering and plasmon-enhanced harmonic generation.

Ultra-large local field enhancement effect of isolated thick triangular silver nanoplates on a silicon substrate in the green waveband.

The local field enhancement in plasmonic nanostructures is vital for surface enhanced Raman scattering (SERS). However, it remains a challenge to achieve a large local field enhancement at an illumination wavelength in the green waveband. Here we report on an ultra-large local field enhancement effect of isolated thick triangular silver nanoplates (ITTSNPs) on a silicon substrate at an illumination wavelength in the green waveband. We show that when the thickness of the ITTSNP is larger than a critical thickness depending on the illumination wavelength, a large local field enhancement with an enhancement factor (EF) greater than 350 can be achieved at an illumination wavelength in the green waveband, which is due to the excitation of strong localized surface plasmon polaritons only at three top apexes of the ITTSNP. Furthermore, we experimentally demonstrate that at an excitation wavelength of 514.5 nm, the average SERS EF of the ITTSNPs can exceed ${{10}^{11}}$1011, and the sensitivity for the detection of Rhodamine 6 G molecules can reach ${{10}^{ - 12}}\;{\rm M}$10-12M.

AMP-activated Protein Kinase Phosphorylation of Angiotensin-Converting Enzyme 2 in Endothelium Mitigates Pulmonary Hypertension.

RATIONALE: Endothelial dysfunction plays an integral role in pulmonary hypertension (PH). AMPK (AMP-activated protein kinase) and ACE2 (angiotensin-converting enzyme 2) are crucial in endothelial homeostasis. The mechanism by which AMPK regulates ACE2 in the pulmonary endothelium and its protective role in PH remain elusive. OBJECTIVES: We investigated the role of AMPK phosphorylation of ACE2 Ser680 in ACE2 stability and deciphered the functional consequences of this post-translational modification of ACE2 in endothelial homeostasis and PH. METHODS: Bioinformatics prediction, kinase assay, and antibody against phospho-ACE2 Ser680 (p-ACE2 S680) were used to investigate AMPK phosphorylation of ACE2 Ser680 in endothelial cells. Using CRISPR-Cas9 genomic editing, we created gain-of-function ACE2 S680D knock-in and loss-of-function ACE2 knockout (ACE2-/-) mouse lines to address the involvement of p-ACE2 S680 and ACE2 in PH. The AMPK-p-ACE2 S680 axis was also validated in lung tissue from humans with idiopathic pulmonary arterial hypertension. MEASUREMENTS AND MAIN RESULTS: Phosphorylation of ACE2 by AMPK enhanced the stability of ACE2, which increased Ang (angiotensin) 1-7 and endothelial nitric oxide synthase-derived NO bioavailability. ACE2 S680D knock-in mice were resistant to PH as compared with wild-type littermates. In contrast, ACE2-knockout mice exacerbated PH, a similar phenotype found in mice with endothelial cell-specific deletion of AMPKα2. Consistently, the concentrations of phosphorylated AMPK, p-ACE2 S680, and ACE2 were decreased in human lungs with idiopathic pulmonary arterial hypertension. CONCLUSIONS: Impaired phosphorylation of ACE2 Ser680 by AMPK in pulmonary endothelium leads to a labile ACE2 and hence is associated with the pathogenesis of PH. Thus, AMPK regulation of the vasoprotective ACE2 is a potential target for PH treatment.

High-Precision and Rapid Direct Laser Writing Using a Liquid Two-Photon Polymerization Initiator.

Two-photon polymerization based direct laser writing (DLW) is an emerging micronano 3D fabrication technology wherein two-photon initiators (TPIs) are a key component in photoresists. Upon exposure to a femtosecond laser, TPIs can trigger the polymerization reaction, leading to the solidification of photoresists. In other words, TPIs directly determine the rate of polymerization, physicochemical properties of polymers, and even the photolithography feature size. However, they generally exhibit extremely poor solubility in photoresist systems, severely inhibiting their application in DLW. To break through this bottleneck, we propose a strategy to prepare TPIs as liquids via molecular design. The maximum weight fraction of the as-prepared liquid TPI in photoresist significantly increases to 2.0 wt %, which is several times higher than that of commercial 7-diethylamino-3-thenoylcoumarin (DETC). Meanwhile, this liquid TPI also exhibits an excellent absorption cross section (64 GM), allowing it to absorb femtosecond laser efficiently and generate abundant active species to initiate polymerization. Remarkably, the respective minimum feature sizes of line arrays and suspended lines are 47 and 20 nm, which are comparable to that of the-state-of-the-art electron beam lithography. Besides, the liquid TPI can be utilized to fabricate various high-quality 3D microstructures and manufacture large-area 2D devices at a considerable writing speed (1.045 m s-1). Therefore, the liquid TPI would be one of the promising initiators for micronano fabrication technology and pave the way for future development of DLW.

Fabrication of patterned solid surfaces with highly controllable wettability.

Precisely controlling the wettability of a solid surface is vital for a wide range of applications such as control of liquid droplet motion, water collection and the directional transport of fluids. However, fabricating a large-area solid surface with highly controllable wettability in a low-cost way is still challenging. Here we present a cost-effective method to fabricate patterned solid surfaces with highly controllable wettability by combining chemical etching technique, chemical vapor deposition technique and laser direct writing technique. We experimentally demonstrated that the contact angle of water droplets on the patterned surfaces of a porous nanofilm fabricated using the presented fabrication method can be adjusted from 94.4° to 168.2° by changing the duty ratio of the periodic pattern on the patterned surfaces. Furthermore, we experimentally demonstrated that the contact angle of water droplets on the patterned surfaces is almost independent of the shape of the unit cell of the patterns. In addition, we propose an effective surface model to accurately calculate the contact angle of water droplets on patterned solid surfaces. Using the effective surface model, the wettability of a patterned solid surface can be precisely controlled by designing the duty ratio of its periodic patterns.

Ag@BiOCl super-hydrophobic nanostructure for enhancing SERS detection sensitivity.

Surface-enhanced Raman scattering (SERS) has received widespread attention in the rapid detection of trace substances. The super-hydrophobic surface of structures has a significant impact on improving SERS performance. Usually a low concentration of objective molecules is randomly distributed in a large area on a non-hydrophobic SERS substrate, resulting in the Raman signals of the molecules not being easily detected. As a solution, a super-hydrophobic surface can gather a large number of probe molecules around the plasmon hot spots to effectively improve Raman SERS detection sensitivity. In this work, a chloride super-hydrophobic surface is fabricated, for the first time, by a simple and low-cost method of combining surface hydrophobic structures with surface modification. The dispersed and uniform hierarchical Ag@BiOCl nanosheet (Ag@BiOCl NSs) substrate has a higher surface-to-volume ratio and rich nano-gap. Such a chip with a high static contact angle of 157.4° exhibits a Raman signal detection limit of R6G dyes up to 10-9 M and an enhancement factor up to 107. This SERS chip with a super-hydrophobic surface offers great potential in practical applications owing to its simple fabricating process, low cost, large area, and high sensitivity.

microRNA-483 ameliorates hypercholesterolemia by inhibiting PCSK9 production.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) affects cholesterol homeostasis by targeting hepatic LDL receptor (LDLR) for lysosomal degradation. Clinically, PCSK9 inhibitors effectively reduce LDL-cholesterol (LDL-C) levels and the incidence of cardiovascular events. Because microRNAs (miRs) are integral regulators of cholesterol homeostasis, we investigated the involvement of miR-483 in regulating LDL-C metabolism. Using in silico analysis, we predicted that miR-483-5p targets the 3'-UTR of PCSK9 mRNA. In HepG2 cells, miR-483-5p targeted the PCSK9 3'-UTR, leading to decreased PCSK9 protein and mRNA expression, increased LDLR expression, and enhanced LDL-C uptake. In hyperlipidemic mice and humans, serum levels of total cholesterol and LDL-C were inversely correlated with miR-483-5p levels. In mice, hepatic miR-483 overexpression increased LDLR levels by targeting Pcsk9, with a significant reduction in plasma total cholesterol and LDL-C levels. Mechanistically, the cholesterol-lowering effect of miR-483-5p was significant in mice receiving AAV8 PCSK9-3'-UTR but not Ldlr-knockout mice or mice receiving AAV8 PCSK9-3'-UTR (ΔBS) with the miR-483-5p targeting site deleted. Thus, exogenously administered miR-483 or similarly optimized compounds have potential to ameliorate hypercholesterolemia.

Imaging of virtual objects with a plane periodic grating.

The purpose of this study is to let a plane periodic grating act as an imaging element for general objects. Using the Fresnel approximation and the Kirchhoff diffraction theory, we investigated an object wave diffracted by a grating. We demonstrated that an image of an original virtual object can be produced by the nth-order monochromatic diffracted wave of a grating. The impulse response of this imaging system and some imaging properties of this imaging system were obtained.

Realization of near-perfect absorption in the whole reststrahlen band of SiC.

Materials used for outdoor radiative cooling technologies need not only be transparent in the solar spectral region, but also need to have a broadband perfect absorption in the infrared atmospheric transparency window (infrared-ATW). Silicon carbide (SiC) has been thought to be a potential candidate for such materials. However, due to the near-perfect reflection of electromagnetic waves in the whole reststrahlen band (RB) of SiC, which is within the infrared-ATW, perfect absorption in the whole RB remains a challenge. Here by constructing a cone-pillar double-structure surface on SiC, a near-perfect absorption (>97%) of normally incident electromagnetic waves in the whole RB has been realized experimentally. Simulation results reveal that the dominant reason for the near-perfect absorption is the efficient coupling of incident electromagnetic waves into the bulk evanescent waves in the free-space wavelength range (10.33 µm, 10.55 µm) and the efficient coupling of incident electromagnetic waves into the surface phonon polaritons in the free-space wavelength range (10.55 µm, 12.6 µm). Our findings open up an avenue to enhance the absorption performance of SiC in infrared-ATW, and may lead to many new applications.

Kaleidoscopic imaging patterns of complex structures fabricated by laser-induced deformation.

Complex surface structures have stimulated a great deal of interests due to many potential applications in surface devices. However, in the fabrication of complex surface micro-/nanostructures, there are always great challenges in precise design, or good controllability, or low cost, or high throughput. Here, we present a route for the accurate design and highly controllable fabrication of surface quasi-three-dimensional (quasi-3D) structures based on a thermal deformation of simple two-dimensional laser-induced patterns. A complex quasi-3D structure, coaxially nested convex-concave microlens array, as an example, demonstrates our capability of design and fabrication of surface elements with this method. Moreover, by using only one relief mask with the convex-concave microlens structure, we have gotten hundreds of target patterns at different imaging planes, offering a cost-effective solution for mass production in lithography and imprinting, and portending a paradigm in quasi-3D manufacturing.

Pushing the resolution of photolithography down to 15nm by surface plasmon interference.

A deep ultraviolet plasmonic structure is designed and a surface plasmon interference lithography method using the structure is proposed to generate large-area periodic nanopatterns. By exciting the anti-symmetric coupled surface plasmon polaritons in the structure, ultrahigh resolution periodic patterns can be formed in a photoresist. The resolution of the generated patterns can be tuned by changing the refractive index and thickness of the photoresist. We demonstrate numerically that one-dimensional and two-dimensional patterns with a half-pitch resolution of 14.6 nm can be generated in a 25 nm-thick photoresist by using the structure under 193 nm illumination. Furthermore, the half-pitch resolution of the generated patterns can be down to 13 nm if high refractive index photoresists are used. Our findings open up an avenue to push the half-pitch resolution of photolithography towards 10 nm.