Generation of a caged lentiviral vector through an unnatural amino acid for photo-switchable transduction.

Application of viral vectors in gene delivery is attracting widespread attention but is hampered by the absence of control over transduction, which may lead to non-selective transduction with adverse side effects. To overcome some of these limitations, we proposed an unnatural amino acid aided caging-uncaging strategy for controlling the transduction capability of a viral vector. In this proof-of-principle study, we first expanded the genetic code of the lentiviral vector to incorporate an azido-containing unnatural amino acid (Nϵ-2-azidoethyloxycarbonyl-l-lysine, NAEK) site specifically within a lentiviral envelope protein. Screening of the resultant vectors indicated that NAEK incorporation at Y77 and Y116 was capable of inactivating viral transduction upon click conjugation with a photo-cleavable chemical molecule (T1). Exposure of the chimeric viral vector (Y77-T1) to UVA light subsequently removed the photo-caging group and restored the transduction capability of lentiviral vector both in vitro and in vivo. Our results indicate that the use of the photo-uncage activation procedure can reverse deactivated lentiviral vectors and thus enable regulation of viral transduction in a switchable manner. The methods presented here may be a general approach for generating various switchable vectors that respond to different stimulations and adapt to different viral vectors.

Overcoming the delivery barrier of oligonucleotide drugs and enhancing nucleoside drug efficiency: The use of nucleolipids.

With the rapid development of synthetic technology and biological technology, many nucleic acid-based drugs have entered the clinical trials. However, their inherent disabilities in actively and efficiently penetrating cell membranes still severely restrict their further application. The main drawback of cationic lipids, which have been widely used as nonviral vectors of nucleic acids, is their high cytotoxicity. A series of nucleoside-based or nucleotide-based nucleolipids have been reported in recent years, due to their oligonucleotide delivery capacity and low toxicity in comparison with cationic lipids. Lipophilic prodrugs of nucleoside analogs have extremely similar structures with nucleolipid vectors and are thus helpful for improving the transmembrane ability. This review introduces the progress of nucleolipids and provides new strategies for improving the delivery efficiency of nucleic acid-based drugs, as well as lipophilic prodrugs of nucleosides or nucleotides for antiviral or anticancer therapies.

Synthesis of a Hexavalent Betulinic Acid Derivative as a Hemagglutinin-Targeted Influenza Virus Entry Inhibitor.

Naturally occurring pentacyclic triterpenes, such as betulinic acid (BA) and its derivatives, exhibit various pharmaceutical activities and have been the subject of great interest, in particular for their antiviral properties. Here, we found a new anti-influenza virus conjugate, hexakis 6-deoxy-6-[4-N-(3ß-hydroxy-lup-20(29)-en-28-oate)aminomethyl-1H-1,2,3-triazol-1-yl]-2,3-di-O-acetyl-α-cyclodextrin (CYY1-11, 1), in a mini library of pentacyclic triterpene-cyclodextrin conjugates by performing a cell-based screening assay and then exploring the underlying mechanisms. Our results showed that conjugate 1 possessed a high-level activity against the influenza virus A/WSN/33 with an IC50 value of 5.20 µM (SI > 38.4). The study of the mechanism of action indicated that conjugate 1 inhibited viral replication by directly targeting the influenza hemagglutinin protein (KD = 1.50 µM), thus efficiently preventing the attachment of the virion to its receptors on host cells and subsequent infection. This study suggests that multivalent BA derivatives have possible use as a new class of influenza virus entry inhibitors.

TF3P: Three-Dimensional Force Fields Fingerprint Learned by Deep Capsular Network.

Molecular fingerprints are the workhorse in ligand-based drug discovery. In recent years, an increasing number of research papers reported fascinating results on using deep neural networks to learn 2D molecular representations as fingerprints. It is anticipated that the integration of deep learning would also contribute to the prosperity of 3D fingerprints. Here, we unprecedentedly introduce deep learning into 3D small molecule fingerprints, presenting a new one we termed as the three-dimensional force fields fingerprint (TF3P). TF3P is learned by a deep capsular network whose training is in no need of labeled data sets for specific predictive tasks. TF3P can encode the 3D force fields information of molecules and demonstrates the stronger ability to capture 3D structural changes, to recognize molecules alike in 3D but not in 2D, and to identify similar targets inaccessible by other 2D or 3D fingerprints based on only ligands similarity. Furthermore, TF3P is compatible with both statistical models (e.g., similarity ensemble approach) and machine learning models. Altogether, we report TF3P as a new 3D small molecule fingerprint with a promising future in ligand-based drug discovery. All codes are written in Python and available at https://github.com/canisw/tf3p.

Evaluation of Cervical Elastography for Prediction of Spontaneous Preterm Birth in Low-Risk Women: A Prospective Study.

OBJECTIVES: The aim of this study was to determine whether cervical elastographic parameters in addition to cervical length (CL) during the 3 trimesters of pregnancy would be predictive of spontaneous preterm birth (sPTB) among low-risk women. METHODS: This work was a prospective nested case-control study evaluating cervical elastographic parameters and CL in low-risk women during the 3 trimesters of pregnancy. A binary logistic regression analysis was used to calculate significant covariates for prediction of sPTB. The area under the curve of the prediction model was calculated by using a receiver operating characteristic curve. RESULTS: There were 286 women (26 cases and 260 controls) included in the analysis. The parameters of cervical elasticity became softened and heterogeneous during the 3 trimesters of pregnancy in both women with and without sPTB. The differences in the mean strain value at the internal os of the cervix (IOS), ratio (strain ratio of the internal os to the external os) during the second trimester and the IOS during the third trimester between the groups had statistical significance (P < .01; P = .01; P < .01, respectively). The CL had no association with sPTB during the 3 trimesters. The IOS during the second trimester was a better predictor of sPTB, with an area under the curve of 0.730, and sensitivity was 72.73%. CONCLUSIONS: We observed multiple elastographic parameters and demonstrated the physiologic changes in the cervix during the 3 trimesters of pregnancy. Furthermore, we found that the IOS during the second trimester can be helpful in predicting sPTB. However, the CL had no association with sPTB during the 3 trimesters of pregnancy.

Quantitative elastography of cervical stiffness during the three trimesters of pregnancy with a semiautomatic measurement program: A longitudinal prospective pilot study.

AIM: To assess the reproducibility of a semiautomatic quantification tool for cervical stiffness and evaluate the normal changes in cervical elasticity during the three trimesters of pregnancy. METHODS: This longitudinal prospective pilot study evaluated cervical elasticity during the three trimesters of pregnancy (11-14, 20-24 and 28-32 weeks) in women with singleton pregnancies. Women with a history of conization, cerclage, cervical Naboth cysts (diameter > 10 mm), cervical tumors, or uterine malformation were excluded. A semiautomatic tool was used to evaluate the stiffness of the whole cervix and the internal and external cervical os with multiple quantitative elasticity parameters and the cervical length (CL) on the sagittal view via transvaginal elastography. Intraclass correlation coefficients (ICC) and Bland-Altman analysis were used to assess intra- and interobserver variability. E-Cervix parameters during the three trimesters were compared using the Friedman test. RESULTS: In total, 217 women with 651 strain examinations during the three trimesters were included. The intra- and interobserver ICC for the E-Cervix parameters ranged from 0.947 to 0.991 and 0.855 to 0.989, respectively. There were significant differences in all parameters among the three trimesters. Cervical elasticity showed significant softening and became heterogeneous during the three trimesters. The median CL was significantly shorter in the first trimester than in the second and third trimesters (P = 0.004, P < 0.001). CONCLUSION: E-Cervix provides a graphical tool for operators to easily define regions of interest and obtain multiple repeatable measures of elasticity. The normal references for E-Cervix parameters during the three trimesters reflect the physiological cervical changes during pregnancy.

Quantitative cervical elastography: a new approach of cervical insufficiency prediction.

OBJECTIVES: To establish methodological criteria for the clinical application of E-cervix technology in non-pregnant women, evaluate cervical differences between non-pregnant CI patients and normal women, and explore the predictive value of E-cervix for CI in non-pregnant women. METHODS: In all, 46 non-pregnant women with CI and 46 non-pregnant women with full-term pregnancy experience were included. Elastic parameters (HR, IOS, EOS, IOS/EOS, CL) of the cervix were measured by transvaginal examination with a mid-sagittal section as the ROI, followed by examination of the whole cervix. The pressure of the probe on the cervix was divided into three levels. The elastic data of three consecutive images were separately obtained by two doctors for three pressure levels. Image stability and the effects of pressure were evaluated and the repeatability of the measurements was tested. In the case and control groups, cervical elasticity images were selected by standardized operation methods. Differences in the parameters between the two groups were determined and the diagnostic efficiency of each parameter was analyzed. RESULTS: The HR, IOS, and EOS showed significant differences when measured on different sequential images obtained by continuous mapping (p < 0.05). The elastic parameters obtained from the first and last two images were significantly different (p < 0.05) and there were no significant differences between the elastic parameters obtained from the last two images (p > 0.05). The HR, IOS, EOS, and IOS/EOS showed significant differences among the pressure levels (p < 0.05), while the IOS showed a significant difference only between grades 0 and 2 (p < 0.05). E-cervix showed good repeatability within and among operators. The elastic parameters obtained by E-cervix in the CI group and control group were significantly different. ROC curve analysis showed that the HR was the most sensitive index for diagnosing CI. CONCLUSION: In E-cervix data acquisition, the first image should be excluded and the probe should not put pressure on the cervix. E-cervix has good retest and inter-observer reliability. Compared with normal women, CI patients showed a relatively softer and shorter cervix. E-cervix can be used as an important diagnostic tool for assessing cervical strain.

Rational Design and Identification of Small-Molecule Allosteric Inhibitors of CD38.

CD38 is a multi-functional signaling enzyme that catalyzes the biosynthesis of two calcium-mobilizing second messengers: cyclic ADP-ribose and nicotinic acid adenine dinucleotide phosphate. It also regulates intracellular nicotinamide adenine dinucleotide (NAD) contents, associated with multiple pathophysiological processes such as aging and cancer. As such, enzymatic inhibitors of CD38 offer great potential in drug development. Here, through virtual screening and enzymatic assays, we discovered compound LX-102, which targets CD38 on the side opposite its enzymatic pocket with a binding affinity of 7.7 µm. It inhibits the NADase activity of CD38 with an IC50 of 14.9 µm. Surface plasmon resonance (SPR) and hydrogen/deuterium exchange and mass spectrometry experiments verified that LX-102 competitively binds to the epitope of the therapeutic SAR 650984 antibody in an allosteric manner. Molecular dynamics simulation was performed to demonstrate the binding dynamics of CD38 with the allosteric ligand. In summary, we established that the cavity to which SAR 650984 binds was an allosteric site and was accessible for the rational design of small chemical modulators of CD38. The lead compound LX-102 that we identified in this study could also be a useful tool for probing CD38 functions and promoting drug discovery.

Construction of a Targeting Nanoparticle of 3',3″-Bis-Peptide-siRNA Conjugate/Mixed Lipid with Postinserted DSPE-PEG2000-cRGD.

The cyclic Arg-Gly-Asp (cRGD) peptides are widely used as tumor-targeting ligands due to their specific binding ability to integrin αvß3, which is overexpressed on the surface of various cancer cells and the endothelial cells of new blood vessels within tumor tissues. In this paper, the postinsertion strategy of DSPE-PEG2000-cRGD has been applied to the nanoparticles of 3',3″-bis-peptide-siRNA (pp-siRNA) encapsulated by gemini-like cationic lipid (CLD) and neutral cytosin-1-yl lipid (DNCA) from our lab. It was confirmed that the nanoparticles of pp-siRNA/CLD/DNCA/DSPE-PEG2000-cRGD (PCNR) were able to specifically target tumor cells with highly expressed integrin αvß3; moreover, it efficiently downregulated the levels of BRAF mRNA and the BRAF protein and inhibited cell proliferation in A375 cells, in comparison with the nontargeted nanocomplex of pp-siRNA/CLD/DNCA/cRAD (PCNA). The uptake pathways of PCNR are mostly dependent on CvME-mediated endocytosis and macropinocytosis in A375 cells, which could bypass lysosome or quickly lead to the lysosomal escape to reduce siRNA degradation. Finally, the biodistribution study showed that PCNR exhibited a high ability to accumulate in tumor tissues. These results suggest that the nanocomplex of PCNR is promising to be highly effective in the treatment of melanomas including their mutation.

Enhanced itaconic acid production in Yarrowia lipolytica via heterologous expression of a mitochondrial transporter MTT.

Itaconic acid, a promising platform chemical, has been applied in many fields of industrial production. As a potential candidate for itaconic acid production, Yarrowia lipolytica possesses several innate abilities such as the tolerance of low-pH and high-shear stress, fast growth rate, cultivation flexibility, and easy for genetic manipulation. Here, Y. lipolytica Po1f which was tested to show high tolerance to itaconic acid could accumulate itaconic acid (0.363 g/L) by expressing the Aspergillus terreus cis-aconitic acid decarboxylase (CAD). Then, we tried to improve the supply and transport of the immediate precursor cis-aconitic acid by overexpressing a series of genes; these results indicate that overexpression of mitochondrial cis-aconitate transporter MTT is beneficial to the itaconic acid biosynthesis in Y. lipolytica. Further culture optimization enabled 22.03 g/L of itaconic acid to be produced in bioreactors, about 60-fold improvement over the initial titer, which is the highest itaconic acid production achieved at low pH by yeast reported worldwide, to data. This study demonstrates the great potential of Y. lipolytica as an industrial platform for itaconic acid production.

Recent progress in the antiviral activity and mechanism study of pentacyclic triterpenoids and their derivatives.

Viral infections cause many serious human diseases with high mortality rates. New drug-resistant strains are continually emerging due to the high viral mutation rate, which makes it necessary to develop new antiviral agents. Compounds of plant origin are particularly interesting. The pentacyclic triterpenoids (PTs) are a diverse class of natural products from plants composed of three terpene units. They exhibit antitumor, anti-inflammatory, and antiviral activities. Oleanolic, betulinic, and ursolic acids are representative PTs widely present in nature with a broad antiviral spectrum. This review focuses on the recent literatures in the antiviral efficacy of this class of phytochemicals and their derivatives. In addition, their modes of action are also summarized.

Discovery of 1-((6-Aminopyridin-3-yl)Methyl)-3-(4-Bromophenyl)Urea as a Potent, Irreversible Myeloperoxidase Inhibitor.

Myeloperoxidase (MPO) is a leukocyte-derived redox enzyme that has been linked to oxidative stress and damage in many inflammatory states, including cardiovascular disease. We have discovered aminopyridines that are potent mechanism-based inhibitors of MPO, with significant selectivity over the closely related thyroid peroxidase. 1-((6-Aminopyridin-3-yl)methyl)-3-(4-bromophenyl)urea (Aminopyridine 2) inhibited MPO in human plasma and blocked MPO-dependent vasomotor dysfunction ex vivo in rat aortic rings. Aminopyridine 2 also showed high oral bioavailability and inhibited MPO activity in vivo in a mouse model of peritonitis. Aminopyridine 2 could effectively be administered as a food admixture, making it an important tool for assessing the relative importance of MPO in preclinical models of chronic inflammatory disease.

Calcium-Mobilizing Behaviors of Neutral Cyclic ADP-Ribose Mimics that Integrate Modifications to the Nucleobase, Northern Ribose and Pyrophosphate.

Cyclic adenosine diphosphate ribose (cADPR) is an endogenous Ca2+ mobilizer involved in diverse cellular processes. Mimics of cADPR play a crucial role in investigating the molecular mechanism(s) of cADPR-mediated signaling. Here, compound 3, a mimic of cADPR in which a neutral triazole moiety and an ether linkage were introduced to substitute the pyrophosphate and "northern" ribose components, respectively, was synthesized for the first time. The pharmacological activities in Jurkat cells indicated that this mimic is capable of penetrating plasma membrane and inciting Ca2+ release from the endoplasmic reticulum (ER) through the action of ryanodine receptors (RyRs) and triggering Ca2+ influx. Furthermore, a uridine moiety was introduced in place of adenine and the new cADPR mimics 4 and 5 were synthesized. The results of biological investigation showed that these mimics also targeted RyRs and retained moderate Ca2+ agonistic activities. The results indicated that the neutral cADPR mimics had the same targets for inducing Ca2+ signaling.

Medium Rings Bearing Bitriazolyls: Easily Accessible Structures with Superior Performance as Cu Catalyst Ligands.

Benefiting from their unique properties, the development of structurally novel and easily accessible medium rings is of significant interest in the pharmaceutical industry and academic research. However, synthetic access to medium-ring scaffolds is very difficult due to their rigid skeleton and large-angle strains. In this paper, a new class of medium rings bearing bitriazolyls (MRBTs) was designed, synthesized, identified as a promising new skeleton ligand for the Cu(I)-catalyzed click reaction, and used in site-special modification of protein. One of the MRBTs, 3aa, exhibited a turnover number (TON) as high as 55 000 and dramatic accelerating effects ( kobs = 1.95 M-1 s-1) and ranked among the most efficient ligands for copper-catalyzed alkyne and azide cycloaddition. Unlike the difficult access to other known medium rings, these 7-12-membered MRBTs can be prepared in straightforward, one-step manner from structurally diverse linear terminal diynes and azides. The unique accessibility and intriguing properties therefore imply their broad application perspectives.

Caged siRNAs with single folic acid modification of antisense RNA for photomodulation of exogenous and endogenous gene expression in cells.

Manually controlling siRNA activity is an essentially important way to spatiotemporally investigate gene expression and function. Owing to ease of operation and precise manipulation, light can be used for controlled regulation of siRNA-induced gene silencing. Here, we developed a series of caged siRNAs with folic acid modification at the 5' terminus of the antisense strand of the siRNA through a photolabile linker. The attachment of the folic acid moiety temporarily masked the corresponding siRNA activity. Upon illumination, these caged siRNAs were activated, and their gene silencing activities were restored. Based on this strategy, we successfully photomodulated gene expression of both an exogenous gene (for green fluorescent protein, GFP) and an endogenous gene (for mototic kinesin-5, Eg5) in cells.

d-/l-Isothymidine incorporation in the core sequence of aptamer BC15 enhanced its binding affinity to the hnRNP A1 protein.

The heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) was reported to participate in the development of a variety of tumors. BC15 is a DNA aptamer targeting hnRNP A1. Firstly, through sequence truncation, we identified 31-mer sequence BC15-31 as the core sequence of BC15 with a strong binding affinity and high selectivity to the hnRNP A1 protein. Isothymidine (isoT) modification was then applied for the structural optimization of BC15-31, systematic modification and biological evaluation were carried out. Incorporation of isoT in the 1,3 sites at the 5'-end of BC15-31 can significantly enhance the protein affinity. Chemical modifications close to the 3'-end can greatly improve the stability of the aptamer. Furthermore, BC15-31 modified with isoT at both the 5'-end and 3'-end displayed an additive effect with enhanced bioactivity and stability at the same time. Our study strategy on BC15 provides a useful guideline for chemical modification and optimization of the aptamer for further clinical application.

Identifying Glyceraldehyde 3-Phosphate Dehydrogenase as a Cyclic Adenosine Diphosphoribose Binding Protein by Photoaffinity Protein-Ligand Labeling Approach.

Cyclic adenosine diphosphoribose (cADPR), an endogenous nucleotide derived from nicotinamide adenine dinucleotide (NAD+), mobilizes Ca2+ release from endoplasmic reticulum (ER) via ryanodine receptors (RyRs), yet the bridging protein(s) between cADPR and RyRs remain(s) unknown. Here we synthesized a novel photoaffinity labeling (PAL) cADPR agonist, PAL-cIDPRE, and subsequently applied it to purify its binding proteins in human Jurkat T cells. We identified glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as one of the cADPR binding protein(s), characterized the binding affinity between cADPR and GAPDH in vitro by surface plasmon resonance (SPR) assay, and mapped cADPR's binding sites in GAPDH. We further demonstrated that cADPR induces the transient interaction between GAPDH and RyRs in vivo and that GAPDH knockdown abolished cADPR-induced Ca2+ release. However, GAPDH did not catalyze cADPR into any other known or novel compound(s). In summary, our data clearly indicate that GAPDH is the long-sought-after cADPR binding protein and is required for cADPR-mediated Ca2+ mobilization from ER via RyRs.

Construction of an inducible stable cell line for efficient incorporation of unnatural amino acids in mammalian cells.

The genetic incorporation of unnatural amino acids (Uaas) with defined properties into proteins at designated sites represents an extremely powerful tool for protein engineering. However, the efficient incorporation of Uaas in response to the amber stop codon in mammalian cells remains a substantial challenge due to the competition from release factor 1(RF1). Addressing this challenge will greatly broaden the power and scope of this technology. Here, we chose the eRF1 mutant, which can selectively enhance Uaa incorporation in response to the amber codon without increasing the readthrough of the opal and ochre codons. Then, we developed an engineered stable cell line using a tetracycline-controlled inducible lentiviral system for the conditional expression of mutant eRF1, which can minimize the potential effect on normal translation termination. Using the eRF1-engineered cells, we provided a 2-fold improvement in the yield of protein containing a Uaa incorporated at a single site, with the protein yield approaching 90% of the wild-type control without the amber codon. Moreover, we achieved the successful incorporation of Uaas at four sites in various proteins at a measured level of 20%.

Redirecting Killer T†Cells through Incorporation of Azido Sugars for Tethering Ligands.

The genetic expression of chimeric antigen receptors (CARs) on the surfaces of T cells enables the redirection of T cell specificity. To enhance the versatility of T cells as tumor-specific killers, we developed a nongenetic approach by which azide-containing sialic acids were metabolically incorporated into T cells to modify cellular sialyl glycans. After successful display of these moieties on the T cells, small-molecule ligands such as RGD and folate (as proof-of-concept, rather than supersized antibodies) were clicked orthogonally, leading to highly selective time- and dose-dependent cytotoxicity to integrin αv ß3 - and folate-receptor-positive cells, respectively. This chemical approach provides a facile platform for rational design of tumor-specific cytotoxic T cells for targeted immunotherapy.