Beclin1 controls the levels of p53 by regulating the deubiquitination activity of USP10 and USP13.

Autophagy is an important intracellular catabolic mechanism that mediates the degradation of cytoplasmic proteins and organelles. We report a potent small molecule inhibitor of autophagy named "spautin-1" for specific and potent autophagy inhibitor-1. Spautin-1 promotes the degradation of Vps34 PI3 kinase complexes by inhibiting two ubiquitin-specific peptidases, USP10 and USP13, that target the Beclin1 subunit of Vps34 complexes. Beclin1 is a tumor suppressor and frequently monoallelically lost in human cancers. Interestingly, Beclin1 also controls the protein stabilities of USP10 and USP13 by regulating their deubiquitinating activities. Since USP10 mediates the deubiquitination of p53, regulating deubiquitination activity of USP10 and USP13 by Beclin1 provides a mechanism for Beclin1 to control the levels of p53. Our study provides a molecular mechanism involving protein deubiquitination that connects two important tumor suppressors, p53 and Beclin1, and a potent small molecule inhibitor of autophagy as a possible lead compound for developing anticancer drugs.

CuI/Oxalamide-Catalyzed Coupling Reaction of (Hetero)aryl Halides with Sodium Nitrite.

The N,N'-bis(thiophen-2-ylmethyl)oxalamide (BTMO) was found to be an effective ligand for Cu-catalyzed ipso-nitration of (hetero)aryl halides (Br, I), making the coupling reaction with sodium nitrite proceed smoothly at 100-120 °C with 1-5 mol % CuI and BTMO. Electron-rich substrates were the best coupling partners to give the desired coupling products in good to excellent yields at 100 °C. Electron-neutral substrates required heating at 120 °C to get complete conversion, while rather low conversions were observed in the case of electron-poor (hetero)aryl bromides.

Nucleophilic Aromatic Substitution of Heteroaryl Halides with Thiols.

The nucleophilic aromatic substitution (SNAr) between heteroaryl halides (Cl, Br) and thiols proceeds smoothly in DMAc under the action of K2CO3 at rt-100 °C. For most electron-deficient heteroarenes, reaction takes place without introducing an additional electron-withdrawing group. For electron-rich heteroarenes, an additional electron-withdrawing group such as a simple ester, keto, cyano, and nitro group is required to ensure the reaction completes. The reactivity trend of heteroaryl halides is highly dependent on the electronic nature of the heteroarenes and orientation of halogens. Besides thiols, a couple of functionalized thioureas and thioamides are compatible with these conditions, providing the corresponding heteroaryl thioethers in good yields.

Discovery of novel macrocyclic derivatives as potent and selective cyclin-dependent kinase 2 inhibitors.

Cyclin-dependent kinase 2 (CDK2) is a member of CDK family of kinases (CDKs) that regulate the cell cycle. Its inopportune or over-activation leads to uncontrolled cell cycle progression and drives numerous types of cancers, especially ovarian, uterine, gastric cancer, as well as those associated with amplified CCNE1 gene. However, developing selective lead compound as CDK2 inhibitors remains challenging owing to similarities in the ATP pockets among different CDKs. Herein, we described the optimization of compound 1, a novel macrocyclic inhibitor targeting CDK2/5/7/9, aiming to discover more selective and metabolically stable lead compound as CDK2 inhibitor. Molecular dynamic (MD) simulations were performed for compound 1 and 9 to gain insights into the improved selectivity against CDK5. Further optimization efforts led to compound 22, exhibiting excellent CDK2 inhibitory activity, good selectivity over other CDKs and potent cellular effects. Based on these characterizations, we propose that compound 22 holds great promise as a potential lead candidate for drug development.

Design, synthesis and evaluation of thieno[3,2-d]pyrimidine derivatives as novel potent CDK7 inhibitors.

The targeting of cyclin-dependent kinase 7 (CDK7) has become a highly desirable therapeutic approach in the field of oncology due to its dual role in regulating essential biological processes, encompassing cell cycle progression and transcriptional control. We have previously identified a highly selective thieno[3,2-d]pyrimidine-based CDK7 inhibitor with demonstrated efficacy and safety in animal model. In this study, we sought to optimize the thieno[3,2-d]pyrimidine core to discover a novel series of CDK7 inhibitors with improved potency and pharmacokinetic (PK) properties. Through extensive structure-activity relationship (SAR) studies, compound 20 has emerged as the lead candidate due to its potent inhibitory activity against CDK7 and remarkable efficacy on MDA-MB-453 cells, a representative triple negative breast cancer (TNBC) cell line. Furthermore, 20 has demonstrated favorable oral bioavailability and exhibited highly desirable pharmacokinetic (PK) properties, making it a promising lead candidate for further structural optimization.

Copper-Catalyzed α-Arylation of Nitroalkanes with (Hetero)aryl Bromides/Iodides.

α-Aryl substituted nitroalkanes are valuable synthetic building blocks that can be easily converted into α-aryl substituted aldehydes, ketones, carboxylic acids, as well as amines. Herein, an efficient Cu/oxalamide-catalyzed coupling between nitroalkanes and (hetero)aryl halides (Br, I) was developed to direct access highly diverse α-aryl substituted nitroalkanes. Compared with the current state of art, this protocol is more environmentally friendly and practical for synthetic chemists. This approach is characterized by a broad substrate scope on both nitroalkane part (primary nitroalkanes and nitromethane) and sp2 halide part ((hetero)aryl bromides/iodides and alkenyl bromides/iodides). The excellent functional group tolerance was observed, which would enable real world synthetic applications. More importantly, TON of current transformation reached to 3640, when some aryl iodides were used as coupling partners. This represents currently the highest catalyst turnover for transition-metal catalyzed α-arylation of nitroalkanes. Furthermore, the successful application in late-stage modification of complex molecules and synthesis of a known retinoid X receptor (RXR) antagonist exemplified its synthetic potential.

CRISPR/Cas9 Disruption of MYB134 and MYB115 in Transgenic Poplar Leads to Differential Reduction of Proanthocyanidin Synthesis in Roots and Leaves.

Proanthocyanidins (PAs) are common specialized metabolites and particularly abundant in trees and woody plants. In poplar (Populus spp.), PA biosynthesis is stress-induced and regulated by two previously studied transcription factors MYB115 and MYB134. To determine the relative contribution of these regulators to PA biosynthesis, we created single- and double-knockout (KO) mutants for both genes in transgenic poplars using CRISPR/Cas9. Knocking out either MYB134 or MYB115 showed reduced PA accumulation and downregulated flavonoid genes in leaves, but MYB134 disruption had the greatest impact and reduced PAs to 30% of controls. In roots, by contrast, only the MYB134/MYB115 double-KOs showed a significant change in PA concentration. The loss of PAs paralleled the lower expression of PA biosynthesis genes and concentrations of flavan-3-ol PA precursors catechin and epicatechin. Interestingly, salicinoids were also affected in double-KOs, with distinct patterns in roots and shoots. We conclude that the regulatory pathways for PA biosynthesis differ in poplar leaves and roots. The residual PA content in the double-KO plants indicates that other transcription factors must also be involved in control of the PA pathway.

Cu/Oxalic Diamide-Catalyzed Coupling of Terminal Alkynes with Aryl Halides.

N1-(2,6-Dimethylphenyl)-N2-(pyridin-2-ylmethyl)oxalamide (DMPPO) was revealed to be a more effective ligand for copper-catalyzed coupling reaction of (hetero)aryl halides with 1-alkynes than previously reported ones. Only 3 mol % CuCl and DMPPO are required to make the coupling complete at 100 °C (for bromides) and 80 °C (for iodides). Both (hetero)aryl and alkyl substituted 1-alkynes worked well under these conditions, leading to the formation of internal alkynes in great diversity.

Copper-Catalyzed Asymmetric Arylation of α-Substituted Cyanoacetates Enabled by Chiral Amide Ligands.

The (S)-nobin-embodied picolinamide and L-hydroxyproline-derived amide are effective ligands for Cu-catalyzed enantioselective coupling reaction of (hetero)aryl iodides with α-alkyl substituted cyanoacetates. This arylation reaction gave α-(heteroaryl)-α-alkyl cyanoacetates in good to excellent enantioselectivities (up to 95 % ee). A variety of functionalized (hetero)aryl and alkyl groups could be introduced to the quaternary center and therefore provided a valuable tool for preparing enantioenriched compounds with an all-carbon quaternary center tethered with convertible functional groups. The size of both α-alkyl and ester groups was proven as the key factor for asymmetric induction.

Divergent Total Syntheses of Napelline-Type C20-Diterpenoid Alkaloids: (-)-Napelline, (+)-Dehydronapelline, (-)-Songorine, (-)-Songoramine, (-)-Acoapetaldine D, and (-)-Liangshanone.

The napelline-type alkaloids possess an azabicyclo[3.2.1]octane moiety and an ent-kaurane-type tetracyclic skeleton (6/6/6/5) along with varied oxidation patterns embedded in the compact hexacyclic framework. Herein, we disclose a divergent entry to napelline-type alkaloids that hinges on convergent assembly of the ent-kaurane core using a diastereoselective intermolecular Cu-mediated conjugate addition and subsequent intramolecular Michael addition reaction as well as rapid construction of the azabicyclo[3.2.1]octane motif via an intramolecular Mannich cyclization. The power of this strategy has been demonstrated through efficient asymmetric total syntheses of eight napelline-type alkaloids, including (-)-napelline, (-)-12-epi-napelline, (+)-dehydronapelline, (+)-12-epi-dehydronapelline, (-)-songorine, (-)-songoramine, (-)-acoapetaldine D, and (-)-liangshanone.

Recent advances in the synthesis of ent-kaurane diterpenoids.

Covering: 2015 to 2020The ent-kaurane diterpenoids are integral parts of tetracyclic natural products that are widely distributed in terrestrial plants. These compounds have been found to possess interesting bioactivities, ranging from antitumor, antifungal and antibacterial to anti-inflammatory activities. Structurally, the different tetracyclic moieties of ent-kauranes can be seen as the results of intramolecular cyclizations, oxidations, C-C bond cleavages, degradation, or rearrangements, starting from their parent skeleton. During the past decade, great efforts have been made to develop novel strategies for synthesizing these natural products. The purpose of this review is to describe the recent advances in the total synthesis of ent-kaurane diterpenoids covering the period from 2015 to date.

In Pursuit of Synthetic Efficiency: Convergent Approaches.

The field of total synthesis has reached a stage in which emphasis has been increasingly focused on synthetic efficiency rather than merely achieving the synthesis of a target molecule. The pursuit of synthetic efficiency, typically represented by step count and overall yield, is a rich source of inspiration and motivation for synthetic chemists to invent innovative strategies and methods. Among them, convergent strategy has been well recognized as an effective approach to improve efficiency. This strategy generally involves coupling of fragments with similar complexity to furnish the target molecule via subsequent cyclization or late-stage functionalization. Thus, methodologies that enable effective connection of fragments are critical to devising a convergent plan. In our laboratory, convergent strategy has served as a long-standing principle for pursuing efficient synthesis during the course of planning and implementing synthetic projects. In this Account, we summarize our endeavors in the convergent synthesis of natural products over the last ten years. We show how we identify reasonable bond disconnections and employ enabling synthetic methodologies to maximize convergency, leading to the efficient syntheses of over two-dozen highly complex molecules from eight disparate families.In detail, we categorize our work into three parts based on the diverse reaction types for fragment assembly. First, we demonstrate the application of a powerful single-electron reducing agent, SmI2, in a late-stage cyclization step, forging the polycyclic skeletons of structurally fascinating Galbulimima alkaloids and Leucosceptrum sesterterpenoids. Next, we showcase how three different types of cycloaddition reactions can simultaneously construct two challenging C-C bonds in a single step, providing concise entries to three distinct families, namely, spiroquinazoline alkaloids, gracilamine, and kaurane diterpenoids. In the third part, we describe convergent assembly of ent-kaurane diterpenoids, gelsedine-type alkaloids, and several drug molecules via employing some bifunctional synthons. To access highly oxidized ent-kaurane diterpenoids, we introduce the hallmark bicyclo[3.2.1]octane ring system at an early stage, and then execute coupling and cyclization by means of a Hoppe's homoaldol reaction and a Mukaiyama-Michael-type addition, respectively. Furthermore, we showcase how the orchestrated combination of an asymmetric Michael addition, a tandem oxidation-aldol reaction and a pinacol rearrangement can dramatically improve the efficiency in synthesizing gelsedine-type alkaloids, with nary a protecting group. Finally, to address the supply issue of several drugs, including anti-influenza drug zanamivir and antitumor agent Et-743, we exploit scalable and practical approaches to provide advantages over current routes in terms of cost, ease of execution, and efficiency.

Cu-Catalyzed Coupling Reactions of Sulfonamides with (Hetero)Aryl Chlorides/Bromides.

Direct N-arylation of sulfonamides is a very attractive approach for preparing pharmaceutically important N-(hetero)aryl sulfonamides because it avoids the potential genotoxic problem resulting from the previous condensation method. Most known catalytic methods suffer from limited reaction scope and inconveniency on metal catalyst and ligand availability. Here we described that the combination of copper and oxalamides (or 4-hydroxypicolinamides) offers a powerful catalytic system for N-arylation of sulfonamides. A wide range of primary and secondary sulfonamides were able to couple with a series of (hetero)aryl bromides in the presence of 2-5 mol % copper salts and oxalamides at 100 °C. Coupling of primary sulfonamides with (hetero)aryl chlorides worked well under the catalysis of Cu2 O and a 4-hydroxypicolinamide. The catalytic method enabled direct sulfonamidation of four chloro-containing marketed drugs and preparation of two sulfonamide drugs from the corresponding aryl halides.

Poplar MYB117 promotes anthocyanin synthesis and enhances flavonoid B-ring hydroxylation by up-regulating the flavonoid 3',5'-hydroxylase gene.

Flavonoids, such as anthocyanins, proanthocyanidins, and flavonols, are widespread plant secondary metabolites and important for plant adaptation to diverse abiotic and biotic stresses. Flavonoids can be variously hydroxylated and decorated; their biological activity is partly dependent on the degree of hydroxylation of the B-ring. Flavonoid biosynthesis is regulated by MYB transcription factors, which have been identified and characterized in a diversity of plants. Here we characterize a new MYB activator, MYB117, in hybrid poplar (Populus tremula×tremuloides). When overexpressed in transgenic poplar plants, MYB117 enhanced anthocyanin accumulation in all tissues. Transcriptome analysis of MYB117-overexpressing poplars confirmed the up-regulation of flavonoid and anthocyanin biosynthesis genes, as well as two flavonoid 3',5'-hydroxylase (F3'5'H) genes. We also identified up-regulated cytochrome b5 genes, required for full activity of F3'5'H . Phytochemical analysis demonstrated a corresponding increase in B-ring hydroxylation of anthocyanins, proanthocyanidins, and flavonols in these transgenics. Similarly, overexpression of F3'5'H1 directly in hybrid poplar also resulted in increased B-ring hydroxylation, but without affecting overall flavonoid content. However, the overexpression of the cytochrome b5 gene in F3'5'H1-overexpressing plants did not further increase B-ring hydroxylation. Our data indicate that MYB117 regulates the biosynthesis of anthocyanins in poplar, but also enhances B-ring hydroxylation by up-regulating F3'5'H1.

Assembly of α-(Hetero)aryl Nitriles via Copper-Catalyzed Coupling Reactions with (Hetero)aryl Chlorides and Bromides.

α-(Hetero)aryl nitriles are important structural motifs for pharmaceutical design. The known methods for direct synthesis of these compounds via coupling with (hetero)aryl halides suffer from narrow reaction scope. Herein, we report that the combination of copper salts and oxalic diamides enables the coupling of a variety of (hetero)aryl halides (Cl, Br) and ethyl cyanoacetate under mild conditions, affording α-(hetero)arylacetonitriles via one-pot decarboxylation. Additionally, the CuBr/oxalic diamide catalyzed coupling of (hetero)aryl bromides with α-alkyl-substituted ethyl cyanoacetates proceeds smoothly at 60 °C, leading to the formation of α-alkyl (hetero)arylacetonitriles after decarboxylation. The method features a general substrate scope and is compatible with various functionalities and heteroaryls.

MYB134-RNAi poplar plants show reduced tannin synthesis in leaves but not roots, and increased susceptibility to oxidative stress.

The importance of the poplar MYB134 gene in controlling condensed tannin (CT) biosynthesis was tested by suppressing its expression using RNA interference (RNAi). MYB134-RNAi plants grew normally but showed reduced accumulation of stress-induced CTs in leaves. RNA-seq analysis indicated that flavonoid- and CT-related genes, as well as additional CT regulators, were strongly and specifically down-regulated by MYB134 suppression. This confirmed that the primary MYB134 target is the leaf flavonoid and CT pathway. Root CT accumulation was not impacted by MYB suppression, suggesting that additional CT regulators are active in roots and emphasizing the complexity of the regulation of CTs in poplar. To test the effect of CT down-regulation on oxidative stress resistance, leaves of MYB134-RNAi and control plants were exposed to the reactive oxygen species generator methyl viologen. MYB134-RNAi leaves sustained significantly more photosystem II damage, as seen in reduced chlorophyll fluorescence, compared with wild-type leaves. MYB134-RNAi leaves also contained more hydrogen peroxide, a reactive oxygen species, compared with the wild type. Our data thus corroborate the hypothesis that CT can act as an antioxidant in vivo and protect against oxidative stress. Overall, MYB134 was shown to be a central player in the regulation of CT synthesis in leaves.

Pre-miR-27a rs895819 polymorphism and risk of diffuse large B-cell lymphoma.

BACKGROUND: Recently, several studies have investigated the relationship between Pre-miR-27a rs895819 polymorphism and risk of various cancers. However, the relationship between rs895819 and diffuse large B-cell lymphoma (DLBCL) has not been well known. METHODS: In this study, we conducted a case-control study to explore the role of Pre-miR-27a rs895819 in risk of DLBCL. The PCR-TaqMan and luciferase assays and in vitro experiments were used to evaluate polymorphism function. RESULTS: As a result, we found subjects carrying with rs895819 AG/GG genotype had a significantly decreased risk when compared with those carrying the AA genotype. Further qPCR assay showed that the DLBCL patients carrying AG/GG genotypes showed a lower level of mature miR-27a when compared with patients carrying AA genotype. Moreover, miR-27a levels were upregulated in DLBCL tissues compared with normal lymphoid tissues. Further in vitro experiments showed that miR-27a might function as an oncogene through target TGFBR1. In addition, TGFBR1 overexpression rescues effects of miR-27a inhibitor on DLBCL cells phenotypes. CONCLUSIONS: In conclusion, these findings indicate that rs895819 A > G might reduce the expression of mature miR-27a, and leading a higher level of TGFBR1, ultimately inhibiting the development of DLBCL.

Total Synthesis of Kopsinitarine†E.

Kopsinitarines A-E are complex octacyclic caged Kopsia alkaloids with strained cage skeletons and a unique cyclic hemiaminal bridge that makes total synthesis challenging. Herein, we disclose the first total synthesis of kopsinitarine E. The key synthetic features include a SmI2 -mediated radical cascade cyclization and a subsequent semi-pinacol rearrangement to install the key carbocyclic skeleton, a chemoselective hydrosilyl amide reduction to construct the hemiaminal ether bridge, and an intramolecular Mannich reaction to establish the highly strained cage system.

Two R2R3-MYB proteins are broad repressors of flavonoid and phenylpropanoid metabolism in poplar.

The phenylpropanoid pathway leads to the production of many important plant secondary metabolites including lignin, chlorogenic acids, flavonoids, and phenolic glycosides. Early studies have demonstrated that flavonoid biosynthesis is transcriptionally regulated, often by a MYB, bHLH, and WDR transcription factor complex. In poplar, several R2R3 MYB transcription factors are known to be involved in flavonoid biosynthesis. Previous work determined that poplar MYB134 and MYB115 are major activators of the proanthocyanidin pathway, and also induce the expression of repressor-like MYB transcription factors. Here we characterize two new repressor MYBs, poplar MYB165 and MYB194, paralogs which comprise a subgroup of R2R3-MYBs distinct from previously reported poplar repressors. Both MYB165 and MYB194 repressed the activation of flavonoid promoters by MYB134 in transient activation assays, and both interacted with a co-expressed bHLH transcription factor, bHLH131, in yeast two-hybrid assays. Overexpression of MYB165 and MYB194 in hybrid poplar resulted in greatly reduced accumulation of several phenylpropanoids including anthocyanins, proanthocyanidins, phenolic glycosides, and hydroxycinnamic acid esters. Transcriptome analysis of MYB165- and MYB194-overexpressing poplars confirmed repression of many phenylpropanoid enzyme genes. In addition, other MYB genes as well as several shikimate pathway enzyme genes were downregulated by MYB165-overexpression. By contrast, leaf aromatic amino acid concentrations were greater in MYB165-overexpressing poplars. Our findings indicate that MYB165 is a major repressor of the flavonoid and phenylpropanoid pathway in poplar, and may also affect the shikimate pathway. The coordinated action of repressor and activator MYBs could be important for the fine tuning of proanthocyanidin biosynthesis during development or following stress.

Oxalic Diamides and tert-Butoxide: Two Types of Ligands Enabling Practical Access to Alkyl Aryl Ethers via Cu-Catalyzed Coupling Reaction.

A robust and practical protocol for preparing alkyl aryl ethers has been developed, which relies on using two types of ligands to promote Cu-catalyzed alkoxylation of (hetero)aryl halides. The reaction scope is very general for a variety of coupling partners, particularly for challenging secondary alcohols and (hetero)aryl chlorides. In case of coupling with aryl chlorides and bromides, two oxalic diamides serve as the powerful ligands. The tert-butoxide is first demonstrated as a ligand for Cu-catalyzed coupling reaction, leading to alkoxylation of aryl iodides complete at room temperature. Additionally, a number of carbohydrate derivatives are applicable for this coupling reaction, affording the corresponding carbohydrate-aryl ethers in 29-98% yields.