Electrochemical Oxo-Fluorosulfonylation of Alkynes under Air: Facile Access to ß-Keto Sulfonyl Fluorides.

Radical fluorosulfonylation is emerging as an appealing approach for the synthesis of sulfonyl fluorides, which have widespread applications in many fields, in particular in the context of chemical biology and drug development. Here, we report the first investigation of FSO2 radical generation under electrochemical conditions, and the establishment of a new and facile approach for the synthesis of ß-keto sulfonyl fluorides via oxo-fluorosulfonylation of alkynes with sulfuryl chlorofluoride as the radical precursor and air as the oxidant. This electrochemical protocol is amenable to access two different products (ß-keto sulfonyl fluorides or α-chloro-ß-keto sulfonyl fluorides) with the same reactants. The ß-keto sulfonyl fluoride products can be utilized as useful building blocks in the synthesis of various derivatives and heterocycles, including the first synthesis of an oxathiazole dioxide compound. Furthermore, some ß-keto sulfonyl fluorides and derivatives exhibited notably potent activities against Bursaphelenchus xylophilus and Colletotrichum gloeosporioides.

Radical Hydro-Fluorosulfonylation of Propargylic Alcohols via Electron Donor-Acceptor Photoactivation.

A radical hydro-fluorosulfonylation of propargyl alcohols with FSO2Cl is presented based on the photoactivation of the electron donor-acceptor (EDA) complex. The reaction avoids the requirement for photocatalysts, bases, hydrogen donor reagents, any other additives, and harsh conditions, enabling the facile synthesis of various functionalized γ-hydroxy (E)-alkenylsulfonyl fluorides. These multifunctional sulfonyl fluorides can be further diversified, providing access to various privileged molecules of biological relevance.

Pharmacokinetic and tissue distribution study of six saponins in the rat after oral administration of Ilex pubescens extract using a validated simultaneous UPLC-qTOF-MS/MS assay.

Ilex pubescens Hook. et Arn is a medicinal plant of the Ilex family that is mainly used for the treatment of cardiovascular diseases. Its main medicinal ingredients are total triterpenoid saponins (IPTS). However, the pharmacokinetics and tissue distribution of the main multi-triterpenoid saponins are lacking. This is the first report that demonstrates a sensitive ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-qTOF-MS/MS) method for the quantification of ilexgenin A (C1), ilexsaponin A1 (C2), ilexsaponin B1 (C3), ilexsaponin B2 (C4), ilexsaponin B3 (DC1) and ilexoside O (DC2) in rat plasma and various tissues of the heart, liver, spleen, lungs, kidney, brain, stomach, duodenum, jejunum, ileum, colon and thoracic aorta. The chromatographic separation was carried out on an Acquity HSS T3 UPLC column (2.1 × 100 mm, 1.8 µm, Waters, USA) with a mobile phase consisting of 0.1% (v/v) formic acid (A) and acetonitrile containing 0.1% (v/v) formic acid (B) at a flow rate of 0.25 mL/min. The MS/MS detection was performed by electrospray ionization (ESI) using selected ion monitoring (SIM) in negative scan mode. The developed quantification method showed good linearity over the concentration range of 10-2000 ng/mL for plasma and 25-5000 ng/mL for tissue homogenates with R2 ≥ 0.990. Lower limits of quantification (LLOQ) was 10 ng/mL in plasma and 25 ng/mL in tissue homogenates. The intra- and inter-day precision were less than 10.39%, and the accuracy was between - 1.03% and 9.13%. The extract recoveries, dilution integrity and matrix effect were well within satisfactory limits. Using the validated method, the pharmacokinetic parameters, including half-life, AUC, Cmax, CL, and MRT, of six triterpenoid saponins in rats after oral administration were provided by establishing their plasma concentration-time curves, while their absolute quantification in various tissues after oral administration was also determined at first, which provides a scientific basis for their clinical application.

Monitoring and spatial traceability of river water quality using Sentinel-2 satellite images.

Due to limited monitoring stations along rivers, it is difficult to trace the specific locations of high pollution areas along the whole river by traditionally in situ measurement. High-spatiotemporal-resolution Sentinel-2 satellite images make it possible to routinely monitor and trace the spatial distributions of river water quality if reliable retrieval algorithms are available. This study took seven major rivers (Qiantang River (QTR), Cao'e River (CEJ), Yongjiang River (YJ), Jiaojiang River (JJ), Oujiang River (OJ), Feiyun River (FYR), and Aojiang River (AJ)) in Zhejiang Province, China, as examples to illustrate the spatial traceability of river water quality parameters (permanganate index (CODMn), total phosphorus (TP), and total nitrogen (TN)) from Sentinel-2 satellite images. The regional retrieval models established for these parameters (CODMn, TP and TN) provided correlation coefficients (R) of 0.68, 0.82, and 0.7, respectively. Based on these models, time-series CODMn, TP, and TN products were obtained for the seven rivers from 2016 to 2021 from Sentinel-2 satellite images, and the results show that the CODMn, TP and TN were high downstream and low upstream; exceptions the CEJ, which was slightly higher in the middle reach than other reaches, and the TN in YJ, which was higher upstream than downstream. The downstream reaches were the main areas suffering from relatively high values in most seasons. Except for the springtime TN level in CEJ, the high value areas were located along the middle reaches. In summer and autumn, the high TN areas in JJ, OJ, and AJ were located along the middle and lower reaches, and the TN in YJ was highest in the upstream. More importantly, this study revealed that the specific locations of high pollution areas along rivers can be effectively traced using Sentinel-2 satellite images, which would be helpful for precise water quality control of rivers.

The m6A Methylation-Regulated AFF4 Promotes Self-Renewal of Bladder Cancer Stem Cells.

The dynamic N6-methyladenosine (m6A) modification of mRNA plays a role in regulating gene expression and determining cell fate. However, the functions of m6A mRNA modification in bladder cancer stem cells (BCSCs) have not been described. Here, we show that global RNA m6A abundance and the expression of m6A-forming enzyme METTL3 are higher in BCSCs than those in non-CSCs of bladder cancer (BCa) cells. The depletion of the METTL3 inhibited the self-renewal of BCSCs, as evidenced by decreased ALDH activity and sphere-forming ability. Mechanistically, METTL3 regulates the m6A modification and thereby the expression of AF4/FMR2 family member 4 (AFF4), knockdown of which phenocopies the METTL3 ablation and diminishes the tumor-initiating capability of BCSCs in vivo. AFF4 binds to the promoter regions and sustains the transcription of SOX2 and MYC which have critical biological functions in BCSCs. Collectively, our results demonstrate the critical roles of m6A modification in self-renewal and tumorigenicity of BCSCs through a novel signaling axis of METTL3-AFF4-SOX2/MYC.

The m6A methyltransferase METTL3 promotes bladder cancer progression via AFF4/NF-κB/MYC signaling network.

N6-methyladenosine (m6A) is the most abundant modification in eukaryotic messenger RNAs (mRNAs), and plays important roles in many bioprocesses. However, its functions in bladder cancer (BCa) remain elusive. Here, we discovered that methyltransferase-like 3 (METTL3), a major RNA N6-adenosine methyltransferase, was significantly up-regulated in human BCa. Knockdown of METTL3 drastically reduced BCa cell proliferation, invasion, and survival in vitro and tumorigenicity in vivo. On the other hand, overexpression of METTL3 significantly promoted BCa cell growth and invasion. Through transcriptome sequencing, m6A sequencing and m6A methylated RNA immuno-precipitation quantitative reverse-transcription polymerase chain reaction, we revealed the profile of METTL3-mediated m6A modification in BCa cells for the first time. AF4/FMR2 family member 4 (AFF4), two key regulators of NF-κB pathway (IKBKB and RELA) and MYC were further identified as direct targets of METTL3-mediated m6A modification. In addition, we showed that besides NF-κB, AFF4 binds to the promoter of MYC and promotes its expression, implying a novel multilevel regulatory network downstream of METTL3. Our results uncovered an AFF4/NF-κB/MYC signaling network operated by METTL3-mediated m6A modification and provided insight into the mechanisms of BCa progression.

Low doses of decitabine improve the chemotherapy efficacy against basal-like bladder cancer by targeting cancer stem cells.

Low dose treatment with the DNA methylation inhibitor decitabine has been shown to be applicable for the management of certain types of cancer. However, its antitumor effect and mechanisms are context dependent and its activity has never been systematically studied in bladder cancer treatment. We used mouse models, cultured cell lines and patient-derived xenografts to demonstrate that low dose decitabine treatment remarkably enhanced the effects of cisplatin and gemcitabine on basal-like bladder cancer both in vivo and in vitro. Genetic lineage tracing revealed that the stemness of a bladder cancer stem cell population was inhibited by decitabine treatment in mice. These effects were accompanied by decreases in genome-wide DNA methylation, gene re-expression, and changes in key cellular regulatory pathways such as STAT3 signaling. These results indicate that this DNA-demethylating reagent is a promising therapeutic approach for basal-like bladder cancer treatment.

Multiple origins of spontaneously arising micronuclei in HeLa cells: direct evidence from long-term live cell imaging.

Although micronuclei (MNi) are extensively used to evaluate genotoxic effects and chromosome instability, the most basic issue regarding their origins has not been completely addressed due to limitations of traditional methods. Recently, long-term live cell imaging was developed to monitor the dynamics of single cell in a real-time and high-throughput manner. In the present study, this state-of-the-art technique was employed to examine spontaneous micronucleus (MN) formation in untreated HeLa cells. We demonstrate that spontaneous MNi are derived from incorrectly aligned chromosomes in metaphase (displaced chromosomes, DCs), lagging chromosomes (LCs) and broken chromosome bridges (CBs) in later mitotic stages, but not nuclear buds in S phase. However, most of bipolar mitoses with DCs (91.29%), LCs (73.11%) and broken CBs (88.93%) did not give rise to MNi. Our data also show directly, for the first time, that MNi could originate spontaneously from (1) MNi already presented in the mother cells; (2) nuclear fragments that appeared during mitosis with CB; and (3) chromosomes being extruded into a minicell which fused with one of the daughter cells later. Quantitatively, most of MNi originated from LCs (63.66%), DCs (10.97%) and broken CBs (9.25%). Taken together, these direct evidences show that there are multiple origins for spontaneously arising MNi in HeLa cells and each mechanism contributes to overall MN formation to different extents.

Next-generation resequencing the complete mitochondrial genome of Japanese quail (Coturnix japonica).

As the development of the new generation of sequencing (NGS) technologies, it has been used for standard sequencing applications more and more popular. We used NGS technologies to resequence the complete mitochondrial genome of Japanese quail. The complete mitochondrial genome of Japanese quail is a 16,668 bp circular molecule, which contains 37 typical mitochondrial genes (13 protein-coding genes, 2 rRNAs, and 22 tRNAs) and a 1156 bp D-loop. Its gene arrangement pattern is identical with typical other Galliformes. All protein-coding genes start with an ATG codon except COI, which start with GTG. TAA is the most frequent stop codon, although ND2 end with TAG, and COI and ND6 end with AGG, COIII and ND4 end with TGC. The mtDNA sequence contains 12S rRNA and 16S rRNA of rRNA. Except for tRNASer(AGY) and tRNALeu(CUN) without the dihydrouridine (DHU) arm, all tRNAs could be folded into canonical cloverleaf secondary structures. Coturnix japonica has close relative with C. chinensis.

SOX2 Is a Marker for Stem-like Tumor Cells in Bladder Cancer.

It has been reported that functionally distinct cancer stem cells (CSCs) exist in human bladder cancer (BCa). Here, we found that Sox2, a transcription factor that is well characterized as a marker for stem cells, is upregulated in both mouse and human BCa. Sox2 expression is absent in normal urothelial cells, but it begins to be expressed in pre-neoplastic bladder tumors and continues to be expressed in invasive mouse BCa. Using s as a reporter of Sox2 transcriptional expression, we demonstrated that Sox2-expressing cells mark a subpopulation of tumor cells that fuel the growth of established BCa. SOX2-positive cells also expressed other previously reported BCa CSC markers, including Keratin14 (KRT14) and CD44v6. Ablation of Sox2-expressing cells within primary invasive BCa led to enhanced tumor regression, supporting the essential role of SOX2-positive cells in regulating BCa maintenance and progression. Our data show that Sox2 is a marker of bladder CSCs and indicate it as a potential clinical target for BCa therapy.

Complete mitochondrial genome of Polyphaga plancyi (Blattaria: Polyphagidae).

The complete mitochondrial genome of Polyphaga plancyi is a 15,547 bp circular molecule, which contains 37 typical mitochondrial genes (13 protein-coding genes, 2 rRNAs and 22 tRNAs) and a 854 bp D-loop. Its gene arrangement pattern is identical with typical other cockroaches. All protein-coding genes start with an ATG codon except COI, ND3, ND5, ND4, ND4L ND6 and ND1. TAA is the most frequent stop codon, and TAG, GCA, TA- and T- are also occurred very common. The mtDNA sequence contains 12S rRNA and 16S rRNA of rRNA. Except for tRNASer(AGY) and tRNALeu(CUN) without the dihydrouridine (DHU) arm, all tRNAs could be folded into canonical cloverleaf secondary structures. The phylogenetic trees from the ML and BI analyses based on the complete mtDNA of nine cockroaches' species, share similar topologies and high node support values. Polyphaga plancy has close relative with Eupolyphaga sinensis.

Difference in microRNA expression and editing profile of lung tissues from different pig breeds related to immune responses to HP-PRRSV.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most devastating diseases for the pig industry. Our goal was to identify microRNAs involved in the host immune response to PRRS. We generated microRNA expression profiles of lung tissues from Tongcheng or Landrace pigs infected with a highly pathogenic PRRS virus (PRRSV) at 3, 5, 7 dpi (day post infection) and control individuals from these two breeds. Our data showed that 278 known and 294 novel microRNAs were expressed in these combined microRNA transcriptomes. Compared with control individuals, almost half of the known microRNAs (116 in Tongcheng and 153 in Landrace) showed significantly differential expression (DEmiRNAs) at least once. The numbers of down-regulated DEmiRNAs were larger than the corresponding number of up-regulated DEmiRNAs in both breeds. Interestingly, miR-2320-5p, which was predicted to bind to conserved sequences of the PRRSV genome, was down-regulated significantly at 3 dpi after PRRSV infection in both breeds. In addition, PRRSV infection induced a significant increase of microRNA editing level in both breeds. Our results provide novel insight into the role of microRNA in response to PRRSV infection in vivo, which will aid the research for developing novel therapies against PRRSV.

Inhibitors of phosphatidylinositol 3'-kinases promote mitotic cell death in HeLa cells.

The phosphatidylinositol 3-kinase (PI3K) pathway plays an important role in many biological processes, including cell cycle progression, cell growth, survival, actin rearrangement and migration, and intracellular vesicular transport. However, the involvement of the PI3K pathway in the regulation of mitotic cell death remains unclear. In this study, we treated HeLa cells with the PI3K inhibitors, 3-methyladenine (3-MA, as well as a widely used autophagy inhibitor) and wortmannin to examine their effects on cell fates using live cell imaging. Treatment with 3-MA decreased cell viability in a time- and dose-dependent manner and was associated with caspase-3 activation. Interestingly, 3-MA-induced cell death was not affected by RNA interference-mediated knockdown (KD) of beclin1 (an essential protein for autophagy) in HeLa cells, or by deletion of atg5 (an essential autophagy gene) in mouse embryonic fibroblasts (MEFs). These data indicate that cell death induced by 3-MA occurs independently of its ability to inhibit autophagy. The results from live cell imaging studies showed that the inhibition of PI3Ks increased the occurrence of lagging chromosomes and cell cycle arrest and cell death in prometaphase. Furthermore, PI3K inhibitors promoted nocodazole-induced mitotic cell death and reduced mitotic slippage. Overexpression of Akt (the downstream target of PI3K) antagonized PI3K inhibitor-induced mitotic cell death and promoted nocodazole-induced mitotic slippage. These results suggest a novel role for the PI3K pathway in regulating mitotic progression and preventing mitotic cell death and provide justification for the use of PI3K inhibitors in combination with anti-mitotic drugs to combat cancer.

Regulation of asymmetrical cytokinesis by cAMP during meiosis I in mouse oocytes.

Mammalian oocytes undergo an asymmetrical first meiotic division, extruding half of their chromosomes in a small polar body to preserve maternal resources for embryonic development. To divide asymmetrically, mammalian oocytes relocate chromosomes from the center of the cell to the cortex, but little is known about the underlying mechanisms. Here, we show that upon the elevation of intracellular cAMP level, mouse oocytes produced two daughter cells with similar sizes. This symmetrical cell division could be rescued by the inhibition of PKA, a cAMP-dependent protein kinase. Live cell imaging revealed that a symmetrically localized cleavage furrow resulted in symmetrical cell division. Detailed analyses demonstrated that symmetrically localized cleavage furrows were caused by the inappropriate central positioning of chromosome clusters at anaphase onset, indicating that chromosome cluster migration was impaired. Notably, high intracellular cAMP reduced myosin II activity, and the microinjection of phospho-myosin II antibody into the oocytes impeded chromosome migration and promoted symmetrical cell division. Our results support the hypothesis that cAMP plays a role in regulating asymmetrical cell division by modulating myosin II activity during mouse oocyte meiosis I, providing a novel insight into the regulation of female gamete formation in mammals.

The fate of micronucleated cells post X-irradiation detected by live cell imaging.

Micronuclei are closely related to DNA damage. The presence of micronuclei in mammalian cells is a common phenomenon post ionizing radiation. The level of micronucleation in tumor cells has been used to predict prognosis after radiotherapy in many cancers. In order to understand how irradiation-induced micronuclei affect cell fate, we performed extensive long-term live cell imaging on X-irradiated nasopharyngeal carcinoma (NPC) cells. To visualize the dynamics of micronuclei more clearly, chromosomes were stably labeled with red fluorescent protein (RFP) by targeting to human histone H2B. Initially, significantly more micronuclei were observed in radiosensitive cells than in radioresistant cells post irradiation. Additionally, cells with micronuclei were found to be more likely to die or undergo cell cycle arrest when compared with micronucleus-free cells after irradiation, and the more micronuclei the cells contained the more likely they would die or undergo arrest. Moreover, micronucleated cells showed predisposition to produce daughter cells with micronuclei through chromosome lagging. Fluorescence in situ hybridization using human pan-centromeric probes revealed that about 70% of these micronuclei and lagging chromosomes did not contain centromeric signals. Finally, DNA damage was more severe and p38 stress kinase activity was higher in micronucleated cells than in micronucleus-free cells as shown by phospho-H2AX and phospho-p38 immunofluorescence staining. Altogether, our observations indicated that the presence of micronuclei coupled with activated DNA damage response could compromise the proliferation capacity of irradiated cells, providing the evidence and justification for using micronucleus index as a valuable biomarker of radiosensitivity.

p53 dependent centrosome clustering prevents multipolar mitosis in tetraploid cells.

BACKGROUND: p53 abnormality and aneuploidy often coexist in human tumors, and tetraploidy is considered as an intermediate between normal diploidy and aneuploidy. The purpose of this study was to investigate whether and how p53 influences the transformation from tetraploidy to aneuploidy. PRINCIPAL FINDINGS: Live cell imaging was performed to determine the fates and mitotic behaviors of several human and mouse tetraploid cells with different p53 status, and centrosome and spindle immunostaining was used to investigate centrosome behaviors. We found that p53 dominant-negative mutation, point mutation, or knockout led to a 2∼ 33-fold increase of multipolar mitosis in N/TERT1, 3T3 and mouse embryonic fibroblasts (MEFs), while mitotic entry and cell death were not significantly affected. In p53-/- tetraploid MEFs, the ability of centrosome clustering was compromised, while centrosome inactivation was not affected. Suppression of RhoA/ROCK activity by specific inhibitors in p53-/- tetraploid MEFs enhanced centrosome clustering, decreased multipolar mitosis from 38% to 20% and 16% for RhoA and ROCK, respectively, while expression of constitutively active RhoA in p53+/+ tetraploid 3T3 cells increased the frequency of multipolar mitosis from 15% to 35%. CONCLUSIONS: p53 could not prevent tetraploid cells entering mitosis or induce tetraploid cell death. However, p53 abnormality impaired centrosome clustering and lead to multipolar mitosis in tetraploid cells by modulating the RhoA/ROCK signaling pathway.