Photocontrolled chiroptical switch based on the self-assembly of azobenzene-bridged bis-tryptophan enantiomers.

Chirality dynamic tuning plays fundamental roles in chemistry, material science and biological system. Herein, a pair of azobenzene-bridged bis-tryptophan enantiomers (Azo-di-d/l-Trp) were designed and synthesized via simple reactions. With the fuel of glucono-δ-lactone (GdL), releasing protons during its hydrolysis, the alkaline solution of Azo-di-d/l-Trp gradually self-assembled into contrast chiral helical structures and displayed magnitude and mirror image of circular dichroism (CD) signals. While the chiral helices converted to CD silent nanoparticles when the azobenzene moiety isomerized from trans- to cis-form under UV irradiation. More importantly, this chiroptical switch, displaying reversible interconversion between chiral amplification and silent, can be smartly controlled via photoirradiation at various wavelengths.

YB-1 Recruits Drosha to Promote Splicing of pri-miR-192 to Mediate the Proangiogenic Effects of H2S.

Aims: The genes targeted by miRNAs have been well studied. However, little is known about the feedback mechanisms to control the biosynthesis of miRNAs that are essential for the miRNA feedback networks in the cells. In this present study, we aimed at examining how hydrogen sulfide (H2S) promotes angiogenesis by regulating miR-192 biosynthesis. Results: H2S promoted in vitro angiogenesis and angiogenesis in Matrigel plugs embedded in mice by upregulating miR-192. Knockdown of the H2S-generating enzyme cystathionine γ-lyase (CSE) suppressed in vitro angiogenesis, and this suppression was rescued by exogenous H2S donor NaHS. Plakophilin 4 (PKP4) served as a target gene of miR-192. H2S up-regulated miR-192 via the VEGFR2/Akt pathway to promote the splicing of primary miR-192 (pri-miR-192), and it resulted in an increase in both the precursor- and mature forms of miR-192. H2S translocated YB-1 into the nuclei to recruit Drosha to bind with pri-miR-192 and promoted its splicing. NaHS treatment promoted angiogenesis in the hindlimb ischemia mouse model and the skin-wound-healing model in diabetic mice, with upregulated miR-192 and downregulated PKP4 on NaHS treatment. In human atherosclerotic plaques, miR-192 levels were positively correlated with the plasma H2S concentrations. Innovation and Conclusion: Our data reveal a role of YB-1 in recruiting Drosha to splice pri-miR-192 to mediate the proangiogenic effect of H2S. CSE/H2S/YB-1/Drosha/miR-192 is a potential therapeutic target pathway for treating diseases, including organ ischemia and diabetic complications. Antioxid. Redox Signal. 36, 760-783. The Clinical Trial Registration number is 2016-224.

Photoreaction-driven two-dimensional periodic polyrotaxane-type supramolecular nanoarchitecture.

A 2D polypseudorotaxane-type assembly was constructed using cucurbit[8]uril and styrylpyridinium-bearing triphenylamine. In addition, tunable non-covalent to covalent transition was achieved by [2+2] photodimerization of styrylpyridinium units. Thus, a more stable 2D polyrotaxane-type nanoarchitecture was obtained, which could capture [60]fullerene and further exhibit an excellent photodynamic therapy effect.

Photocontrolled reversible conversion of a lamellar supramolecular assembly based on cucurbiturils and a naphthalenediimide derivative.

Lamellar and helical supramolecular assemblies were constructed using cucurbiturils and a naphthalenediimide derivative. More interestingly, the formation of the lamellar assembly could be reversibly photocontrolled via competitive binding with α-cyclodextrin and water-soluble azobenzene.

Hydrotreatment of bio-oil distillates produced from pyrolysis and hydrothermal liquefaction of duckweed: A comparison study.

A comprehensive comparison of hydrothermal liquefaction (HTL) to the pyrolysis of duckweed was conducted to determine the yields and components of the crude bio-oils and their distillates. The upgrading behaviors of the distillates were thoroughly investigated with the use of used engine oil as a solvent. With all other variables fixed, HTL produced crude bio-oil with a lower H/C ratio (1.28 ±â€¯0.03) than pyrolysis did (1.45 ±â€¯0.04). However, its distillates had a higher H/C ratio (1.60 ±â€¯0.05) and total yield (66.1 ±â€¯2.0 wt%) than pyrolysis (1.46 ±â€¯0.04 and 47.2 ±â€¯1.4 wt%, respectively). Phenolics and nitrogenous heterocycles constituted relatively major proportions of the two crude bio-oils and most of their distillates. Obvious differences in molecular composition between the two crude bio-oils and their distillates were ascribed to the distinct impacts of HTL and pyrolysis and were affected by the distillate temperature. Co-hydrotreating with used engine oil (UEO) provided the upgraded bio-oils much higher H/C ratios (~1.78 ±â€¯0.05) and higher heating values (~45.5 ±â€¯1.4 MJ·kg-1), as well as much lower contents of N, O and S compared to their initial distillates. Aromatics and alkanes constituted a large proportion in most of upgraded bio-oils. N removal from the pyrolysis distillates was easier than from the HTL distillates. Distinct differences in yields and molecular compositions for the upgraded bio-oils were also attributed to the different influences associated with the two conversion routes.

H2S regulates endothelial nitric oxide synthase protein stability by promoting microRNA-455-3p expression.

The aims of the present study are to determine whether hydrogen sulfide (H2S) is involved in the expression of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) production, and to identify the role of microRNA-455-3p (miR-455-3p) during those processes. In cultured human umbilical vein endothelial cells (HUVECs), the expression of miR-455-3p, eNOS protein and the NO production was detected after administration with 50 µM NaHS. The results indicated that H2S could augment the expression of miR-455-3p and eNOS protein, leading to the increase of NO level. We also found that overexpression of miR-455-3p in HUVECs increased the protein levels of eNOS whereas inhibition of miR-455-3p decreased it. Moreover, H2S and miR-455-3p could no longer increase the protein level of eNOS in the presence of proteasome inhibitor, MG-132. In vivo, miR-455-3p and eNOS expression were considerably increased in C57BL/6 mouse aorta, muscle and heart after administration with 50 µmol/kg/day NaHS for 7 days. We also identified that H2S levels and miR-455-3p expression increased in human atherosclerosis plaque while H2S levels decreased in plasma of atherosclerosis patients. Our data suggest that the stability of eNOS protein and the NO production could be regulated by H2S through miR-455-3p.

Size Switchable Supramolecular Nanoparticle Based on Azobenzene Derivative within Anionic Pillar[5]arene.

A photo/thermal-switchable supramolecular nanoparticles assembly has been constructed based on an inclusion complex between anionic pillar[5]arene 2C-WP5A and azobenzene derivative Azo-py-OMe (G). The novel anionic pillar[5]arene-based host-guest inclusion complexation was investigated by the 1H NMR titration, 2D ROESY and isothermal titration microcalorimetry (ITC) showing high association constant (Ka) of (2.60 ± 0.06) × 104 M-1 with 1:1 binding stoichiometry. Furthermore, the supramolecular nanoparticles assembly can be conveniently obtained from G and a small amount of 2C-WP5A in aqueous solution, which was so-called "host induced aggregating (HIA)". The size and morphology of the supramolecular nanoparticles assembly were characterized by TEM and DLS. As a result of the photo/thermal-isomerization of G included in the cavity of 2C-WP5A, the size of these nanoparticles could reversibly change from ~800 nm to ~250 nm, which could switch the solution of this assembly from turbid to clear.

Hydrogen sulfide promotes angiogenesis by downregulating miR-640 via the VEGFR2/mTOR pathway.

We previously found hydrogen sulfide (H2S) to be a new proangiogenic factor. However, the mechanisms underlying the cardiovascular effect of this small gas molecule remain largely unknown. The aim of the present study was to identify the essential microRNAs (miRNAs) involved in the transduction of H2S signals in vascular endothelial cells (ECs). The expression of miR-640 and its signaling elements, vascular endothelial growth factor receptor 2 (VEGFR2), hypoxia inducible factor 1-α (HIF1A), and mammalian target of rapamycin (mTOR), was measured using quantitative PCR and Western blotting. Overexpression and inhibition of miR-640 were performed to clarify their roles in mediating the effect of H2S. In addition, knockdown of VEGFR2, HIF1A, and mTOR was performed using siRNAs, dominant negative mutants, or inhibitors to examine their roles in the transduction of the H2S signals. miR-640 levels decreased in vascular ECs that were treated with H2S, whereas overexpression of miR-640 blunted the proangiogenic effect of H2S. Knockdown of either VEGFR2 or mTOR blunted the downregulation of miR-640 and the proangiogenic effect induced by H2S. In addition, miR-640 bound to the 3'-UTR of HIF1A mRNA and then inhibited the expression of HIF1A. The inhibition could be recovered by treating cells with H2S. Thus we concluded that miR-640 plays a pivotal role in mediating the proangiogenic effect of H2S; H2S acts through downregulation of the expression of miR-640 and increasing the levels of HIF1A through the VEGFR2-mTOR pathway.

Molecular binding behaviors and thermodynamics of ferrocenyl dimethylaminium derivatives by anionic pillar[5]arene.

A novel anionic water-soluble pillar[5]arene (4C-WP5A) was synthesized via a convenient synthetic strategy of the direct cyclization of a functionalized hydroquinone monomer. The alkyl chain dependent affinities of ferrocenyl aminiums (FCn(+), n: carbon number) with 4C-WP5A are driven by hydrophobic interactions and desolvations with assisted C-H···π interactions and electrostatic interactions.

VEGFR2 functions as an H2S-targeting receptor protein kinase with its novel Cys1045-Cys1024 disulfide bond serving as a specific molecular switch for hydrogen sulfide actions in vascular endothelial cells.

AIMS: The potential receptor for hydrogen sulfide (H2S) remains unknown. RESULTS: H2S could directly activate vascular endothelial growth factor receptor 2 (VEGFR2) and that a small interfering RNA (siRNA)-mediated knockdown of VEGFR2 inhibited H2S-induced migration of human vascular endothelial cells. H2S promoted angiogenesis in Matrigel plug assay in mice and this effect was attenuated by a VEGF receptor inhibitor. Using tandem mass spectrometry (MS), we identified a new disulfide complex located between Cys1045 and Cys1024 within VEGFR2 that was labile to H2S-mediated modification. Kinase activity of the mutant VEGFR2 (C1045A) devoid of the Cys1045-Cys1024 disulfide bond was significantly higher than wild-type VEGFR2. Transfection with vectors expressing VEGFR2 (C1045A) caused a significant increase in cell migration, while the migration-promoting effect of H2S disappeared in the cells transfected with VEGFR2 (C1045A). Therefore, the Cys1045-Cys1024 disulfide bond serves as an intrinsic inhibitory motif and functions as a molecular switch for H2S. The formation of the Cys1045-Cys1024 disulfide bond disrupted the integrity of the active conformation of VEGFR2. Breaking the Cys1045-Cys1024 disulfide bond recovered the active conformation of VEGFR2. This motif was prone to a nucleophilic attack by H2S via an interaction of their frontier molecular orbitals. siRNA-mediated knockdown of cystathionine γ-lyase attenuated migration of vascular endothelial cells induced by VEGF or moderate hypoxia. INNOVATION AND CONCLUSION: The study provides the first piece of evidence of a molecular switch in H2S-targeting receptor protein kinase in H2S-induced angiogenesis and that may be applicable to additional kinases containing functionally important disulfide bonds in mediating various H2S actions.

[Involvement of HIF-1 in the migration-promoting effects of hydrogen sulfide in vascular endothelial cells under normoxic conditions].

The purpose of this study was to investigate the molecular mechanisms whereby hydrogen sulfide (H2S) exerts the promoting effect on vascular endothelial cells migration. We used wound healing assay to study the effect of NaHS (H2S donor) on the migration ability of rhesus retinal pigment epithelial cell line, RF/6A cells, under normoxic conditions. Real-time PCR was used to measure hypoxia-inducible factor 1α (HIF-1α) mRNA level. Western blot was used to measure the expression of HIF-1α protein. The probe 2',7'-dichlorofluorescein diacetate (DCFH-DA) was used to measure intracellular reactive oxygen species (ROS) level. The results showed that NaHS (10-100 µmol/L) could significantly promote RF/6A cells migration under normoxic conditions, and this effect could be inhibited by 50 µmol/L HIF-1 inhibitor, CdCl2. NaHS increased the protein level of HIF-1α in a dose- and time-dependent manner, and up-regulated the mRNA level of HIF-1α quickly and continuously. Moreover, NaHS could significantly decrease ROS levels in RF/6A cells under normoxic conditions. These results suggest HIF-1 may mediate the promoting effect of H2S on vascular endothelial cells migration under normoxic conditions. ROS, as an upstream regulator of HIF-1α, may be involved in the migration-promoting effect of H2S.

Hydrogen sulfide protects cardiomyocytes from hypoxia/reoxygenation-induced apoptosis by preventing GSK-3beta-dependent opening of mPTP.

Hydrogen sulfide (H(2)S) is an endogenously generated gaseous transmitter, which has recently been suggested to regulate cardiovascular functions. The present study aims to clarify the mechanisms underlying the cardioprotective effects of H(2)S. Signaling elements were examined in cardiomyocytes cultured under hypoxia/reoxygenation conditions and in a rat model of ischemia-reperfusion. In cultured cardiomyocytes, sodium hydrosulfide (NaHS; 10, 30, and 50 mumol/l) showed concentration-dependent inhibitory effects on cardiomyocyte apoptosis induced by hypoxia/reoxygenation. These effects were associated with an increase in phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) (Ser9) and a decrease in Bax translocation, caspase-3 activation, and mitochondrial permeability transition pore (mPTP) opening. Transfection of a phosphorylation-resistant mutant of GSK-3beta at Ser9 attenuated the effects of NaHS in reducing cardiomyocyte apoptosis, Bax translocation, caspase-3 activation, and mPTP opening. In a rat model of ischemia-reperfusion, NaHS administration reduced myocardial infarct size and increased the phosphorylation of GSK-3beta (Ser9) at a dose of 30 mumol/kg. In conclusion, the H(2)S donor prevents cardiomyocyte apoptosis by inducing phosphorylation of GSK-3beta (Ser9) and subsequent inhibition of mPTP opening.