MicroRNA-499a-5p Promotes Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells to Cardiomyocytes

Since the adult mammalian heart has limited regenerative capacity, cardiac trauma, disease, and aging cause permanent loss of contractile tissue. This has fueled the development of stem cell-based strategies to provide the damaged heart with new cardiomyocytes. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are capable of self-renewal and differentiation into cardiomyocytes, albeit inefficiently. MicroRNAs (miRNAs, miRs) are non-coding RNAs that have the potential to control stem cell fate decisions and are employed in cardiac regeneration and repair. In this study, we tested the hypothesis that overexpression of miR-499a induces cardiomyogenic differentiation in BM-MSCs. Human BM-MSCs (hBM-MSCs) were transduced with lentiviral vectors encoding miR-499a-3p or miR-499a-5p and analyzed by immunostaining and western blotting methods 14 days post-transduction. MiR-499a-5p-transduced cells adopted a polygonal/rod-shaped (myocyte-like) phenotype and showed an increase in the expression of the cardiomyocyte markers α-actinin and cTnI, as cardiogenic differentiation markers. These results indicate that miR-499a-5p overexpression promotes the cardiomyogenic differentiation of hBM-MSCs and may thereby increase their therapeutic efficiency in cardiac regeneration.     

Electrochemical behaviour of triphenylgermanium bromide

The electrochemical behaviour of triphenylgermanium bromide has been thoroughly investigated using various electrochemical techniques including polarography, cyclic voltammetry and controlled potential coulometry. It has been found that in non-aqueous solvents triphenylgermanium bromide gives only one small drawn-out wave, while in aqueous-organic media two reduction waves are observed. The first wave has been ascribed to adsorption of the products of the reduction step II. The triphenylgermanium free radicals have been postulated to combine rapidly with protons in acidic media or to abstract hydrogen from water in alkaline media. The protonated species has been found to be reduced at potentials at which normal reduction of triphenylgermanium bromide takes place giving rise to a superimposed catalytic proton-discharge wave. A mechanism of reduction of triphneylgermanium bromide at the DME has been postulated and analytical methods for the determination of triphenylgermanium compounds at the formulation and trace analysis levels have been developed.     

Electrochemical behaviour of biological macromolecules

Biomacromolecules play a key role in basic life processes. The complexity of their structures and properties has up to now been a bar to a theoretical treatment of their adsorption onto electrically charged surfaces. On the other hand, research into the interactions of biomacromolecules with electrodes has brought forward much important information on the properties and conformation of these substances in solution and on electrode surfaces.In the last five years significant progress has been made in the study of the properties and structure of genetic material (DNA) using polarographic (voltammetric) methods in conjunction with mercury electrodes. By means of these methods it is possible to distinguish single-strand DNA from double-strand DNA (on the basis of differences in their adsorbability and reducibility) and to detect minor local changes in the structure of the DNA double helix. Apart from the cathodic signals previously observed, which are caused by reduction of adenine and cytosine residues, the anodic signal (using cyclic voltammetry) caused by guanine residues is useful for this purpose. The application of cyclic voltammetry in conjunction with adsorptive preconcentration of DNA has allowed an increase in the sensitivity by about two orders of magnitude, so that submicrogram amounts of DNA can now be analysed electrochemically.Osmium tetroxide and chloroacetaldehyde have been used as DNA structural probes, capable of introducing a stable electroactive marker into the polynucleotide chain. The presence of this marker in DNA can be detected with high sensitivity using electrochemical methods. Osmium-labelled DNA can be determined by means of stripping voltammetry at nanogram quantities. Thanks to the great increase in sensitivity and the application of electroactive structural probes it is now possible to use electrochemical methods in the analysis of recombinant-DNA molecules of viruses and plasmids, which play an important role in the current development of molecular biology and genetics. Osmium is a suitable electroactive marker not only for nucleic acids but also for proteins and other biomacromolecules.     

Electrochemical behaviour of Cu-NTA complexes

The deposition of copper was found to involve adsorbed monovalent copper which follows nonactivated Temkin isotherm. The presence of nitrilotriacetic acid stabilises it and the second electron transfer is slow.     

Electrochemical behaviour of V2O5 xerogel in aqueous LiNO3 solution

By dissolving crystalline V₂O₅ in hydrogen peroxide and drying at elevated temperature, the V₂O₅ xerogel was obtained. Its electrochemical behaviour was examined in aqueous solution of LiNO₃ by both cyclic voltammetry and galvanostatic charging/discharging cycling. Peak-to-peak potential separation observed at the cyclovoltammograms indicated fast Li⁺ intercalation/deintercalation reactions. Initial discharge capacity amounted to 69 mAhg^?1, and after 100 charging/discharging cycles, capacity fade amounted to 11% only. This presents a remarkable improvement in comparison with the behaviour of crystalline, vanadium oxide based, lithium intercalates in aqueous electrolytes.     

Electrochemical and spectral properties of thienylene-polyparaphenylenevinylene derivative stereoisomers

Four new compounds: 1,4-dimetoxy-2,5-bis[2-(tien-2-yl)ethenyl]benzene), 1,4-dietoxy-2,5-bis[2-(tien-2-yl)ethenyl]benzene), 1,4-isopropyloxy-2,5-bis[2-(tien-2-yl)ethenyl]benzene) and 1,4-dietoksy-2,5-bis[2-(5-methylthiophen-2-yl)ethenyl]benzene are synthesized. Three steroisomers ZZ, EZ and EE are isolated from the reaction mixture for the first two of them. Third compound is fully converted to the most stable EE form. Polymerization of all isomers leads to identical polymeric product. Mechanism of polymerization is recognized by using model molecule with methyl substituents blocking α-, α′-sites. All seven stereoisomers have photoluminescent properties. Detailed spectral and electrochemical studies reveal isomerization phenomena during oxidation or at light exposure. Published in Russian in Elektrekhimiya, 2006, Vol. 42, No. 12, pp. 1401–1408. Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes.” October 18–22, 2005, Moscow. The text was submitted by the authors in English.     

Electrochemical behaviour of some polyoxo clusters

We describe the redox behaviour in non-aqueous solvents of some cyclopentadienyl(oxo)titanium derivatives. The derivative [Ti₄{η⁵-C₅H₄(SiMe₃)}₄(μ-O)₆] shows an electrochemically and chemically reversible le reduction process, followed by a multi-electron, chemically complicated reduction at a fairly cathodic potential. On the basis of the overall electrochemical features and the comparison with the redox behaviour of the quasi-planar compound [[Ti{η⁵-C₅H₄(SiMe₃)}Cl(μ-O)]₄] we propose an EECCEE mechanism for the first derivative, where the second electron-transfer induces a cascade of chemical reactions giving rise to irreversible cluster breakdown. The electrochemically induced fragmentation can be viewed as a retrosynthetic pathway. The heterometallic derivative [{Ti(η⁵-C₅H₄Me)₂(μ₂-MoO₄)₂}₂] shows two consecutive reduction processes; the first is chemically reversible, and the second quasi-reversible. The molybdate bridges apparently increase the stability of the electrogenerated anions. However none of these poly-oxo clusters can be considered as good models of electron ‘sinks’.     

Electrochemical behaviour of zinc gluconate complexes

Voltammetric studies revealed that under transient conditions in the pH range 3.7 to 5.0, the deposition of zinc from ZnSO₄ solutions involves the formation of adsorbed monovalent zinc. The conversion of divalent zinc to monovalent is a slow step. In the presence of gluconate, the reduction of divalent complex involves the monovalent zinc complex and the second electron transfer is slow. In the pH range 10 to 12.5, the zinc complex may be [(Zn(GH₄)₄]2^- and is found to vary with gluconate and OH^- ions. The conversion of [Zn(GH₄)(OH)_abs ^-] to Zn(OH)₂ or Zn(GH₄)₂ is the slow step in the reduction of the complexes. In strong alkali solutions sodium gluconate forms zinc hydroxy gluconate complexes. [Zn(OH)₃(GH₄)]^2- to adsorbed [Zn(OH)(GH₄)]^- is the slow step in the reduction.     

Electrochemical behaviour of alkaline copper complexes

A search for non-cyanide plating baths for copper resulted in the development of alkaline copper complex baths containing trisodium citrate [TSC] and triethanolamine [TEA]. Voltammetric studies were carried out on platinum to understand the electrochemical behaviour of these complexes. In TSC solutions, the deposition of copper involves the slow formation of a monovalent species. Adsorption of this species obeys Langmuir isotherm. In TEA solutions the deposition involves the formation of monovalent ions obeying the non-activated Temkin isotherm. Conversion of divalent to monovalent copper is also slow. In TEA and TSC alkaline copper solutions, the predominant species that undergo stepwise reduction contain only TEA ligands.     

Electrochemical behaviour of RSSR thiuram disulfides

The electrochemical behaviour of tetraalkylthiuram disulfides (RSSR) has been investigated by using cyclic voltammetry at various scan rates, temperatures, and for several organic moieties R. The experiments have been run for solutions of RSSR in acetonitrile, and also for solutions of dithiocarbamate salts (RS⁻). These experiments show that RSSR is reducible into RSSR⁻, but this latter is unstable, decomposing into RS⁻ and RS^·. Furthermore, RSSR is partly dissociated into 2RS^·, which is also a reducible species. A model is proposed, involving two redox couples RS^·/RS⁻ and RSSR/RSSR⁻. The corresponding voltammograms have been simulated and fitted to the experimental voltammograms at several temperatures. The experimental observation of the reduction of RS^· for tetraisopropylthiuram disulfide solutions supports the proposed model.     

Electrochemical and spectral characterization of blue copper protein models

Blue copper proteins play a central role in various enzymatic anabolic/catabolic pathways in living cells by virtue of the integrated metal ions. These ions may exist in variable oxidation states, with suitable reduction potentials and fast electron-transfer rates which in turn is a manifestation of their unusual geometry and co-ordination. We report the electrochemical and spectral characterization of three novel complexes of copper (II) with N₂S type tridentate chelating agent 2,2′-dithiodianiline (dta), having structural similarities to the active site of Type I copper proteins. High positive redox potentials in the range of 0.5–0.6 V vs Ag/AgCl electrode of the complexes and the absorption maxima at ～550 nm, with high extinction coefficients, correspond well with typical blue copper proteins. The IR and EPR studies support the assigned pseudo tetrahedral structures to the complexes. The diffusion coefficient and rate constant for heterogeneous charge transfer for Cu²⁺/Cu⁺ coordinated in a potentially bio-mimetic Type I site is reported.     

Electrochemical and spectral properties of hexacoordinate polypyridyl silicon complexes

Various salts of tetracationic tris(2,2′-bipyridine)silicon(IV) and bis(2,2′;6′,2″-terpyridine)silicon(IV) were synthesized by reaction of SiI₄ with the appropriate ligand followed by metathesis reactions. The resulting salts exhibit multiple, chemically reversible one-electron reduction waves that are significantly shifted to less negative reduction potentials than the corresponding ruthenium analogs. The salts also exhibit anion dependent ion pair charge transfer bands throughout the visible spectrum. Weak, low energy emission is observed from Si(bipy)₃Br₄ and Si(terpy)₂Br₄ in the solid state at 77 K when the sample is excited in the ion pair charge transfer band.     

hnRNPC induces isoform shifts in miR-21-5p leading to cancer development

MicroRNA (miRNA) processing is a critical step in mature miRNA production. Its dysregulation leads to an increase in miRNA isoforms with heterogenous 5′-ends (isomiRs), which can recognize distinct target sites because of their shifted seed sequence. Although some miRNA genes display productive expression of their 5′-isomiRs in cancers, how their production is controlled and how 5′-isomiRs affect tumor progression have yet to be explored. In this study, based on integrative analyses of high-throughput sequencing data produced by our group and publicly available data, we demonstrate that primary miR-21 (pri-miR-21) is processed into the cancer-specific isomiR isomiR-21-5p | ±1, which suppresses growth hormone receptor (GHR) in liver cancer. Treatment with antagomirs against isomiR-21-5p | ±1 inhibited the in vitro tumorigenesis of liver cancer cells and allowed the recovery of GHR, whereas the introduction of isomiR-21-5p | ±1 mimics attenuated these effects. These effects were validated in a mouse model of spontaneous liver cancer. Heterogeneous nuclear ribonucleoprotein C and U2 small nuclear RNA auxiliary factor 2 were predicted to bind upstream of pre-miR-21 via a poly-(U) motif and influence Drosha processing to induce the production of isomiR-21-5p | ±1. Our findings suggest an oncogenic function for the non-canonical isomiR-21-5p | ±1 in liver cancer, and its production was shown to be regulated by hnRNPC.Subject terms: RNAi, Liver cancer     

MiR-330-3p and miR-485-5p as biomarkers for glioblastoma: An integrated bioinformatics and experimental study

Glioblastoma Multiforme (GBM) is the most common, invasive, and malignant primary brain tumor with a poor prognosis and a median survival of 12–15 months. This study tried to identify the most significant miRNA biomarkers in both tissue and serum samples of GBM. GSE25632 was employed from gene expression omnibus and using WGCNA package, association of miRNA networks and clinical data was explored and brown and green modules identified as the most relevant modules. Independently, Limma package was utilized to identify differentially expressed miRNAs (DEMs) in GSE25632 by cutoff $\left|\text{l}\text{o}\text{g}\text{F}\text{C}\right|$ > 2 and P.value < 0.05. By merging the results of Limma and WGCNA, the miRNAs that were in brown and green modules and had mentioned cutoff were selected as hub miRNAs. Performing enrichment analysis, Pathways in cancer, Prostate cancer, Glioma, p53 signaling pathway, and Focal adhesion were identified as the most important signaling pathways. Based on miRNA- target genes, has-mir-330−3p and has-mir-485−5p were identified as core miRNAs. The expression level of core miRNAs was validated by GSE90604, GSE42657, and GSE93850. We evaluated the expression level of common target genes of two detected core genes based on GSE77043, GSE42656, GSE22891, GSE15824, and GSE122498. The ability of detected miRNAs to discriminate GBM from healthy controls was assessed by area under the curve (AUC) using the ROC curve analysis. Based on TCGA database, we tested the prognostic significance of miRNAs using overall survival analysis. We evaluated the expression level of the miRNAs in tissue of 83 GBM patients and also non-tumoral adjacent (as control) tissues. We used serum samples of 34 GBM patients to evaluate the expression levels of the hub miRNAs compare to the controls. Our results showed that has-mir-330−3p and has-mir-485−5p could be potential biomarkers in GBM.     

Electrochemical behaviour of ferrocenyl-containing acyl thiourea derivatives

Twenty four N-ferrocenoyl-N-aryl(alkyl or ferrocenyl) thiourea derivatives were prepared and ten of them investigated by cyclic voltammetric method in DMF or CH2Cl2 solutions. The compounds exhibit a higher redox potential than ferrocene. Although distant from the redox centre, the substituents on N can influence the redox potential of ferrocenyl via intramolecular hydrogen bonding.     

Electrochemical behaviour of isopropanol at platinum electrodes

The accessible potential range of isopropanol was found to be from +1.1 to -1.2 V vs. Ag/AgCl in non-aqueous 0.01 M LiCl, with acetone being formed at the anode and hydrogen at the cathode. Water was formed in a side-reaction, probably by ketal formation, the rate being proportional to the electrode area. Another side-reaction at the cathode produced an insoluble product after prolonged electrolysis. The coulometric current efficiency was nevertheless very high (99.6-99.97%) and almost independent of current density. The results indicate that the cathode reaction proceeded with somewhat less than theoretical current efficiency.     

Electrochemical behaviour of azaferrocenes and reactivity of azaferrocenium cations

The electrooxidation of azaferrocene (AF) and 2,5-dimethylazaferrocene (DMAF) has been investigated in several solvents and under various conditions of basicity and nucleophilicity, by cyclic voltammetry at scan rates ranging between 1 and 500 V s⁻¹. The kinetics of the AF⁺ cation decomposition have been found to be first order (vs. the substrate), and strongly dependent on both the solvent and the possible presence of a base. The results tend to demonstrate that the decomposition of AF⁺ cations is more probably associated with a deprotonation reaction than with a nucleophilic attack.     

Electrochemical behaviour of quinazoline in amphiprotic media

The electrochemical behaviour of quinazoline in aqueous methanolic solutions has been studied in detail. In acid solutions two single-electron waves of equal height are obtained whereas in neutral solutions a single two-electron wave is observed. Quinazoline gets reduced to tetrahydroquinazoline in alkaline media and very interestingly gives reverse cathodic peaks during cyclic voltammetric experiments. The polarographic waves are diffusion-controlled and irreversible on the basis of the usual criteria. Based on the results obtained, reduction schemes are given for quinazoline in various buffered media. A comparison of the electrochemical behaviour, between quinazoline and 4-(2-thienyl)quinazoline (4-TQ) has been attempted.

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Das elektrochemische Verhalten von Chinazolin in amphiprotischen Medien

Zusammenfassung Das elektrochemische Verhalten von Chinazolin in wäßrigen methanolischen Lösungen wurde im Detail untersucht. In sauren Lösungen wurden zwei Einelektronenwellen gleicher Höhe erhalten, währenddessen in neutralen Lösungen eine einzige Zweielektronenwelle beobachtet wurde. Chinazolin wird in alkalischem Medium zu Tetrahydrochinazolin reduziert und ergibt interessanterweise kathodische Umkehrpeaks während cyclischer voltammetrischer Experimente. Die polarographischen Wellen sind diffusionskontrolliert und nach den üblichen Kriterien irreversibel. Aufgrund dieser Ergebnisse werden Reduktionsschemata für Chinazolin in verschiedenen Puffermedien angegeben. Es wird ein Vergleich zwischen dem elektrochemischen Verhalten von Chinazolin und 4-(2-Thienyl)-chinazolin (4-TQ) angestellt.

     

Electrochemical behaviour of tin in alkaline electrolyte

The electrochemical behaviour of two types of tin electrodes, Sn rod and electrodeposited Sn is investigated in 0.1 M KOH_aq in order to evaluate processes related to anodic Sn dissolution. Potential regions of formation of soluble Sn(II) and Sn(IV) are identified by means of a rotating ring disk electrode. An anodic reactivation peak observed for cathodic potential scans for partially passivated electrodes is accompanied by formation of soluble Sn(II) species and a minimum in the imaginary part of the impedance. This confirms that the reactivation peak is due to active dissolution of metallic Sn exposed to the electrolyte during rupture of the oxidised layer.