Exploring the Functional Heterogeneity of Directly Reprogrammed Neural Stem Cell-Derived Neurons via Single-Cell RNA Sequencing.

The therapeutic potential of directly reprogrammed neural stem cells (iNSCs) for neurodegenerative diseases relies on reducing the innate tumorigenicity of pluripotent stem cells. However, the heterogeneity within iNSCs is a major hurdle in quality control prior to clinical applications. Herein, we generated iNSCs from human fibroblasts, by transfecting transcription factors using Sendai virus particles, and characterized the expression of iNSC markers. Using immunostaining and quantitative real time -polymerase chain reaction (RT -qPCR), no differences were observed between colonies of iNSCs and iNSC-derived neurons. Unexpectedly, patch-clamp analysis of iNSC-derived neurons revealed distinctive action potential firing even within the same batch product. We performed single-cell RNA sequencing in fibroblasts, iNSCs, and iNSC-derived neurons to dissect their functional heterogeneity and identify cell fate regulators during direct reprogramming followed by neuronal differentiation. Pseudotime trajectory analysis revealed distinct cell types depending on their gene expression profiles. Differential gene expression analysis showed distinct NEUROG1, PEG3, and STMN2 expression patterns in iNSCs and iNSC-derived neurons. Taken together, we recommend performing a predictable functional assessment with appropriate surrogate markers to ensure the quality control of iNSCs and their differentiated neurons, particularly before cell banking for regenerative cell therapy.

A Convergent Synthetic Strategy towards Oligosaccharides containing 2,3,6-Trideoxypyranoglycosides.

A de novo synthetic strategy for the production of oligosaccharides containing 2,3,6-trideoxypyranoglycoside is reported. The key event is the Pd-catalyzed asymmetric diastereoselective hydroalkoxylation of ene-alkoxyallene-linked glycosidic fragments. The utility of this approach was demonstrated by the activation-free, stereodivergent, and convergent synthesis of various 2-deoxyoligosaccharides, as well as their aglycon conjugates.

Pd-Catalyzed Regioselective Asymmetric Addition Reaction of Unprotected Pyrimidines to Alkoxyallene.

Catalytic asymmetric synthesis of N-heterocyclic glycosides free of protecting and directing groups is reported. The key reaction is highlighted by the atom-efficient and regioselective addition of unprotected pyrimidines to highly functionalized alkoxyallene. Numerous acyclic and cyclic N-heterocyclic glycosides are accessed with minimal formation of organic byproducts. The synthetic utility of the reaction is demonstrated by the first catalytic asymmetric synthesis of anticancer pharmaceutical (-)-Tegafur and stereoselective synthesis of an oxepane nucleoside derivative.

De Novo Synthesis of Furanose Sugars: Catalytic Asymmetric Synthesis of Apiose and Apiose-Containing Oligosaccharides.

A de novo synthetic method towards apiose, a structurally unusual furanose, is reported. The key feature is sequential metal catalysis consisting of the palladium-catalyzed asymmetric intermolecular hydroalkoxylation of an alkoxyallene and subsequent ring-closing metathesis (RCM). This strategy enabled the efficient synthesis of various apiose-containing disaccharides and a unique convergent synthesis of trisaccharides.

TGF-ß Suppresses COX-2 Expression by Tristetraprolin-Mediated RNA Destabilization in A549 Human Lung Cancer Cells.

PURPOSE: Overexpression of cyclooxygenase 2 (COX-2) is thought to promote survival of transformed cells. Transforming growth factor ß (TGF-ß) exerts anti-proliferative effects on a broad range of epithelial cells. In the current study, we investigated whether TGF-ß can regulate COX-2 expression in A549 human lung adenocarcinoma cells, which are TGF-ß-responsive and overexpress COX-2. MATERIALS AND METHODS: Western blotting, Northern blotting, and mRNA stability assays were performed to demonstrate that COX-2 protein and mRNA expression were suppressed by TGF-ß. We also evaluated the effects of tristetraprolin (TTP) on COX-2 mRNA using RNA interference. RESULTS: We demonstrated that COX-2 mRNA and protein expression were both significantly suppressed by TGF-ß. An actinomycin D chase experiment demonstrated that COX-2 mRNA was more rapidly degraded in the presence of TGF-ß, suggesting that TGF-ß-induced inhibition of COX-2 expression is achieved via decreased mRNA stability. We also found that TGF-ß rapidly and transiently induced the expression of TTP, a well-known mRNA destabilizing factor, before suppression of COX-2 mRNA expression was observed. Using RNA interference, we confirmed that increased TTP levels play a pivotal role in the destabilization of COX-2 mRNA by TGF-ß. Furthermore, we showed that Smad3 is essential to TTP-dependent down-regulation of COX-2 expression in response to TGF-ß. CONCLUSION: The results of this study show that TGF-ß down-regulated COX-2 expression via mRNA destabilization mediated by Smad3/TTP in A549 cells.

Synthesis of the tricyclic core in stemonamine alkaloids via one-pot gold(I)-catalyzed cyclization and schmidt rearrangement: formal synthesis of (±)-stemonamine.

An efficient synthesis of the tricyclic cyclopenta[1,2-b]pyrrolo[1,2-a]azepine nucleus of stemonamine alkaloids is reported. The key reaction utilizes a one-pot gold(I)-catalyzed cyclization and SnCl4-mediated Schmidt rearrangement. Notably, the phosphine ligand had a crucial effect on the gold(I)-catalyzed cyclization. As an application of this new methodology, the formal synthesis of (±)-stemonamine has been accomplished.

Access to trans-3,4-dihydroxy-2-alkylpyrrolidines and piperidines by use of stereodefined cyclic N,O-acetals as a diversity-generating element.

A highly efficient and stereoselective synthetic pathway towards trans-3,4-dihydroxy-2-alkylpyrrolidines and piperidines is described. The nature of the protecting groups on the hydroxyl moieties played a crucial role on the trans selectivity. By using this method, a concise total synthesis of (-)-2-epilentiginosine has been achieved.

Stereoselective synthesis of 4-substituted-cyclic sulfamidate-5-carboxylates by asymmetric transfer hydrogenation accompanied by dynamic kinetic resolution and applications to concise stereoselective syntheses of (-)-epi-cytoxazone and the taxotere side-chain.

Dynamic kinetic resolution driven, asymmetric transfer hydrogenation reactions of cyclic sulfamidate imine-5-carboxylate esters were developed. Applications of the new methodology to stereoselective syntheses of the taxotere side-chain and (-)-epi-cytoxazone are described.

Stereoselective synthesis of norephedrine and norpseudoephedrine by using asymmetric transfer hydrogenation accompanied by dynamic kinetic resolution.

Each of the enantiomers of both norephedrine and norpseudoephedrine were stereoselectively prepared from the common, prochiral cyclic sulfamidate imine of racemic 1-hydroxy-1-phenyl-propan-2-one by employing asymmetric transfer hydrogenation (ATH) catalyzed by the well-defined chiral Rh-complexes, (S,S)- or (R,R)-Cp*RhCl(TsDPEN), and HCO(2)H/Et(3)N as the hydrogen source. The ATH processes are carried out under mild conditions (rt, 15 min) and are accompanied by dynamic kinetic resolution.

Dynamic kinetic resolution in the stereoselective synthesis of 4,5-diaryl cyclic sulfamidates by using chiral rhodium-catalyzed asymmetric transfer hydrogenation.

The dynamic kinetic resolution of 4,5-diaryl cyclic sulfamidate imines was achieved via asymmetric transfer hydrogenation using a HCO(2)H/Et(3)N mixture as the hydrogen source and chiral Rh catalysts (R,R)- or (S,S)-RhCl(TsDPEN)Cp* affording the corresponding cyclic sulfamidates in good yields with up to >20 : 1 dr and up to >99% ee.

Enantioselective synthesis of cyclic sulfamidates by using chiral rhodium-catalyzed asymmetric transfer hydrogenation.

Asymmetric transfer hydrogenation (ATH) of cyclic sulfamidate imines 4 and 9, using a HCO(2)H/Et(3)N mixture as the hydrogen source and well-defined chiral Rh catalysts (S,S)- or (R,R)-2, Cp*RhCl(TsDPEN), effectively produces the corresponding cyclic sulfamidates with excellent yields and enantioselectivities at room temperature within 0.5 h. ATH of 4,5-disubstituted imines 9, having preexisting stereogenic centers, is shown to take place with dynamic kinetic resolution.

Highly efficient, enantioselective syntheses of (S)-(+)- and (R)-(-)-dapoxetine starting with 3-phenyl-1-propanol.

A highly efficient, enantioselective sequence has been developed for the synthesis of (S)- and (R)-dapoxetine. The pathways involve the intermediacy of the 6-membered-ring sulfamate esters 4, which were generated by Du Bois asymmetric C-H amination reactions of the prochiral sulfamate 3, catalyzed by the chiral dirhodium(II) complexes. During the course of our research, the absolute configuration of the enantiomer of 4-pheny[1,2,3]oxathiazinane 2,2-dioxide (4r), prepared by the Du Bois asymmetric C-H amination reaction of 3 and the Rh(2)(S-nap)(4) catalyst, is determined to be R and not S as was originally reported.

The growth inhibitory effect of lapatinib, a dual inhibitor of EGFR and HER2 tyrosine kinase, in gastric cancer cell lines.

HER2 overexpression is observed in 5-25% of gastric cancers. Lapatinib is a dual inhibitor of the epidermal growth factor receptor and HER2 tyrosine kinase. We examined the antitumor effect of lapatinib in gastric cancer cell lines. Lapatinib induced selective and potent growth inhibition in two HER2-amplified gastric cancer cell lines (SNU-216 and NCI-N87). Lapatinib inhibited the phosphorylation of HER2, EGFR and downstream signaling proteins, resulting in G1 arrest in both cell lines with down-regulation of cMyc and induction of p27kip1. Lapatinib also induced apoptosis in NCI-N87 which has high HER2 amplification ratio. Lapatinib combined with 5-fluorouracil, cisplatin, oxaliplatin or paclitaxel showed an additive or synergistic effect. These results provide a rationale for the future clinical trials of lapatinib combined with cytotoxic drugs in the treatment of HER2-positive gastric cancer.