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1.
PLoS Pathog ; 19(12): e1011853, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38100526

ABSTRACT

Engineered T cells hold great promise to become part of an effective HIV cure strategy, but it is currently unclear how best to redirect T cells to target HIV. To gain insight, we generated engineered T cells using lentiviral vectors encoding one of three distinct HIV-specific T cell receptors (TCRs) or a previously optimized HIV-targeting chimeric antigen receptor (CAR) and compared their functional capabilities. All engineered T cells had robust, antigen-specific polyfunctional cytokine profiles when mixed with artificial antigen-presenting cells. However, only the CAR T cells could potently control HIV replication. TCR affinity enhancement did not augment HIV control but did allow TCR T cells to recognize common HIV escape variants. Interestingly, either altering Nef activity or adding additional target epitopes into the HIV genome bolstered TCR T cell anti-HIV activity, but CAR T cells remained superior in their ability to control HIV replication. To better understand why CAR T cells control HIV replication better than TCR T cells, we performed a time course to determine when HIV-specific T cells were first able to activate Caspase 3 in HIV-infected targets. We demonstrated that CAR T cells recognized and killed HIV-infected targets more rapidly than TCR T cells, which correlates with their ability to control HIV replication. These studies suggest that the speed of target recognition and killing is a key determinant of whether engineered T cell therapies will be effective against infectious diseases.


Subject(s)
HIV Infections , HIV-1 , Receptors, Chimeric Antigen , Humans , Receptors, Chimeric Antigen/genetics , Receptors, Antigen, T-Cell/genetics , HIV Infections/therapy , Virus Replication
2.
Small ; 20(25): e2307986, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38189535

ABSTRACT

The volume collapse and slow kinetics reaction of anode materials are two key issues for sodium ion batteries (SIBs). Herein, an "embryo" strategy is proposed for synthesis of nanorod-embedded MoO2/MoS2/C network nanoarchitecture as anode for SIBs with high-rate performance. Interestingly, L-cysteine which plays triple roles including sulfur source, reductant, and carbon source can be utilized to produce the sulfur vacancy-enriched heterostructure. Specifically, L-cysteine can combine with metastable monoclinic MoO3 nanorods at room temperature to encapsulate the "nutrient" of MoOx analogues (MoO2.5(OH)0.5 and MoO3·0.5H2O) and hydrogen-deficient L-cysteine in the "embryo" precursor affording for subsequent in situ multistep heating treatment. The resultant MoO2/MoS2/C presents a high-rate capability of 875 and 420 mAh g-1 at 0.5 and 10 A g-1, respectively, which are much better than the MoS2-based anode materials reported by far. Finite element simulation and analysis results verify that the volume expansion can be reduced to 42.8% from 88.8% when building nanorod-embedded porous network structure. Theoretical calculations reveal that the sulfur vacancies and heterointerface engineering can promote the adsorption and migration of Na+ leading to highly enhanced thermodynamic and kinetic reaction. The work provides an efficient approach to develop advanced electrode materials for energy storage.

3.
Molecules ; 29(13)2024 Jul 05.
Article in English | MEDLINE | ID: mdl-38999159

ABSTRACT

Poly(p-phenylene ethynylene) (PPE) molecular wires are one-dimensional materials with distinctive properties and can be applied in electronic devices. Here, the approach called first-principles quantum transport is utilized to investigate the PPE molecular wire field-effect transistor (FET) efficiency limit through the geometry of the gate-all-around (GAA) instrument. It is observed that the n-type GAA PPE molecular wire FETs with a suitable gate length (Lg = 5 nm) and underlap (UL = 1, 2, 3 nm) can gratify the on-state current (Ion), power dissipation (PDP), and delay period (τ) concerning the conditions in 2028 to achieve the higher performance (HP) request of the International Roadmap for Device and Systems (IRDS, 2022 version). In contrast, the p-type GAA PPE molecular wire FETs with Lg = 5, 3 nm, and UL of 1, 2, 3 nm could gratify the Ion, PDP, and τ concerning the 2028 needs to achieve the HP request of the IRDS in 2022, while Lg = 5 and UL = 3 nm could meet the Ion and τ concerning the 2028 needs to achieve the LP request of the IRDS in 2022. More importantly, this is the first one-dimensional carbon-based ambipolar FET. Therefore, the GAA PPE molecular wire FETs could be a latent choice to downscale Moore's law to 3 nm.

4.
Curr Issues Mol Biol ; 45(11): 9060-9075, 2023 Nov 13.
Article in English | MEDLINE | ID: mdl-37998745

ABSTRACT

Chaylte vine, the tender shoot of Sechium edule, is popular among vegetable consumers because of its high nutritional content, crisp texture, and unique flavor. Existing studies on the nutrient composition of chaylte vines are mostly simple chemical determinations, which have limited the breeding of specialized cultivars and the development of related industries. Using metabolomics combined with transcriptomics, this study analyzed the metabolic characteristics and related molecular mechanisms of two common varieties of chaylte vines: green-skinned (SG) and white-skinned (SW). Between the two varieties, a total of 277 differentially accumulated metabolites (DAMs) and 739 differentially expressed genes (DEGs) were identified. Furthermore, chemical assays demonstrated that the SW exhibited a higher total flavonoid content and antioxidant capacity. In conclusion, it was found that the SG samples exhibited a higher diversity of flavonoid subclasses compared to the SW samples, despite having a lower total flavonoid content. This inconsistent finding was likely due to the differential expression of the phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) genes in the two varieties. These results laid the foundation for investigating the mechanisms involved in flavonoid regulation and the breeding of specialized S. edule cultivars for chaylte vine production.

5.
Curr Issues Mol Biol ; 45(7): 5305-5316, 2023 Jun 25.
Article in English | MEDLINE | ID: mdl-37504253

ABSTRACT

This review presents a systematic analysis of the studies on volatiles in Dendrobium. Among the various components, aromatic terpenes are a crucial component in the development of the aromatic characteristics of Dendrobium and other plants. Recent advancements in detection and sequencing technology have resulted in a considerable rise in research on the biosynthetic processes of aromatic terpenes in Dendrobium and other flowering plants. Nevertheless, the inquiry into the precise means by which plants regulate the proportion of diverse aromatic terpenes in their floral scent, thereby preserving their olfactory traits, requires further investigation. A conjecture on the botanical perfumer mechanism, which condensed the findings of earlier studies, was put forward to address this area of interest. Specific transcription factors likely govern the coordinated expression of multiple key terpene synthase (TPS) genes during the flowering stage of plants, thereby regulating the proportional biosynthesis of diverse aromatic terpenes and sustaining the distinctive aromatic properties of individual plants. This review serves as a significant theoretical reference for further investigations into aromatic volatile compounds in Dendrobium.

6.
Int J Mol Sci ; 24(11)2023 May 24.
Article in English | MEDLINE | ID: mdl-37298170

ABSTRACT

GM2 gangliosidosis is a group of genetic disorders that result in the accumulation of GM2 ganglioside (GM2) in brain cells, leading to progressive central nervous system (CNS) atrophy and premature death in patients. AB-variant GM2 gangliosidosis (ABGM2) arises from loss-of-function mutations in the GM2 activator protein (GM2AP), which is essential for the breakdown of GM2 in a key catabolic pathway required for CNS lipid homeostasis. In this study, we show that intrathecal delivery of self-complementary adeno-associated virus serotype-9 (scAAV9) harbouring a functional human GM2A transgene (scAAV9.hGM2A) can prevent GM2 accumulation in in GM2AP-deficient mice (Gm2a-/- mice). Additionally, scAAV9.hGM2A efficiently distributes to all tested regions of the CNS within 14 weeks post-injection and remains detectable for the lifespan of these animals (up to 104 weeks). Remarkably, GM2AP expression from the transgene scales with increasing doses of scAAV9.hGM2A (0.5, 1.0 and 2.0 × 1011 vector genomes (vg) per mouse), and this correlates with dose-dependent correction of GM2 accumulation in the brain. No severe adverse events were observed, and comorbidities in treated mice were comparable to those in disease-free cohorts. Lastly, all doses yielded corrective outcomes. These data indicate that scAAV9.hGM2A treatment is relatively non-toxic and tolerable, and biochemically corrects GM2 accumulation in the CNS-the main cause of morbidity and mortality in patients with ABGM2. Importantly, these results constitute proof-of-principle for treating ABGM2 with scAAV9.hGM2A by means of a single intrathecal administration and establish a foundation for future preclinical research.


Subject(s)
G(M2) Ganglioside , Gangliosidoses, GM2 , Humans , Animals , Mice , G(M2) Ganglioside/metabolism , Mutation , Central Nervous System/metabolism , Brain/metabolism , G(M2) Activator Protein/genetics , Gangliosidoses, GM2/genetics
7.
Int J Mol Sci ; 24(19)2023 Sep 27.
Article in English | MEDLINE | ID: mdl-37834060

ABSTRACT

GM2 gangliosidoses are a group of neurodegenerative lysosomal storage disorders that are characterized by the accumulation of GM2 gangliosides (GM2), leading to rapid neurological decline and death. The hydrolysis of GM2 requires the specific synthesis, processing, and combination of products of three genes-HEXA, HEXB, and GM2A-within the cell's lysosomes. Mutations in these genes result in Tay-Sachs disease, Sandhoff disease, or AB-variant GM2 gangliosidosis (ABGM2), respectively. ABGM2, the rarest of the three types, is characterized by a mutation in the GM2A gene, which encodes the GM2 activator (GM2A) protein. Being a monogenic disease, gene therapy is a plausible and likely effective method of treatment for ABGM2. This study aimed at assessing the effects of administering a one-time intravenous treatment of single-stranded Adeno-associated virus serotype 9 (ssAAV9)-GM2A viral vector at a dose of 1 × 1014 vector genomes (vg) per kilogram per mouse in an ABGM2 mouse model (Gm2a-/-). ssAAV9-GM2A was administered at 1-day (neonatal) or 6-weeks of age (adult-stage). The results demonstrated that, in comparison to Gm2a-/- mice that received a vehicle injection, the treated mice had reduced GM2 accumulation within the central nervous system and had long-term persistence of vector genomes in the brain and liver. This proof-of-concept study is a step forward towards the development of a clinically therapeutic approach for the treatment of patients with ABGM2.


Subject(s)
Gangliosidoses, GM2 , Tay-Sachs Disease , Humans , Animals , Mice , Dependovirus/genetics , Serogroup , Tay-Sachs Disease/therapy , Gangliosidoses, GM2/genetics , Gangliosidoses, GM2/therapy , G(M2) Activator Protein/genetics , Genetic Therapy
8.
J Org Chem ; 87(2): 1154-1172, 2022 01 21.
Article in English | MEDLINE | ID: mdl-34985891

ABSTRACT

Novel phenanthridinone analogues with an all-carbon quaternary stereocenter have been enantioselectively synthesized using the Birch-Heck sequence. Flat phenanthridinone structures have extensive bioactivity but consequently also suffer from poor therapeutic selectivity. The addition of a quaternary center to the phenanthridinone skeleton has the potential to generate more complex analogues with improved selectivity. Unfortunately, no general synthetic pathway to such derivatives exists. Herein we report a four-step process that transforms inexpensive benzoic acid into 22 different quaternary carbon-containing phenanthridinone analogues with a variety of substituents on all three rings: alkyl groups at the quaternary center; methyl, methoxymethyl, or para-methoxybenzyl on the amide nitrogen; and halogen and methyl substituents on the aryl ring. Good to very good enantioselectivity was demonstrated in the key intramolecular desymmetrizing Mizoroki-Heck reaction. Transformations of the Heck reaction products into molecules with potentially greater therapeutic relevance were also accomplished.


Subject(s)
Betula , Carbon , Amides , Catalysis , Stereoisomerism
9.
J Immunol ; 204(2): 335-347, 2020 01 15.
Article in English | MEDLINE | ID: mdl-31836655

ABSTRACT

Epitope density has a profound impact on B cell responses to particulate Ags, the molecular mechanisms of which remain to be explored. To dissect the role of epitope density in this process, we have synthesized a series of liposomal particles, similar to the size of viruses, that display a model self-antigen peptide at defined surface densities. Immunization of C57BL/6J mice using these particles elicited both IgM and class-switched IgG1, IgG2b, and IgG3 autoreactive Abs that depended on the epitope density. In C57BL/6 gene knockout mice lacking either functional TCRs or MHC class II molecules on B cells, the liposomal particles also elicited IgM, IgG1, IgG2b, and IgG3 responses that were comparable in magnitudes to wild-type mice, suggesting that this B cell response was independent of cognate T cell help. Notably, the titer of the IgG in wild-type animals could be increased by more than 200-fold upon replacement of liposomes with bacteriophage Qß virus-like particles that displayed the same self-antigen peptide at comparable epitope densities. This enhancement was lost almost completely in gene knockout mice lacking either TCRs or MHC class II molecules on B cells. In conclusion, epitope density above a threshold on particulate Ags can serve as a stand-alone signal to trigger secretion of autoreactive and class-switched IgG in vivo in the absence of cognate T cell help or any adjuvants. The extraordinary immunogenicity of Qß viral-like particles relies, in large part, on their ability to effectively recruit T cell help after B cell activation.


Subject(s)
Autoantibodies/blood , Immunoglobulin G/blood , Liposomes/metabolism , T-Lymphocytes, Helper-Inducer/immunology , Animals , Autoantigens/immunology , Cells, Cultured , Cytokines/metabolism , Epitopes, B-Lymphocyte/metabolism , Immunoglobulin Class Switching , Mice , Mice, Inbred C57BL , Mice, Knockout , Nanoparticles/metabolism , Peptides/immunology , Tumor Necrosis Factor-alpha/immunology , Virion/immunology
10.
Nanomedicine ; 32: 102328, 2021 02.
Article in English | MEDLINE | ID: mdl-33181274

ABSTRACT

The aim of this study is to evaluate the feasibility of using blood serum surface-enhanced Raman spectroscopy (SERS) to identify benign and malignant thyroid nodules. Blood serum samples collected from three different groups including healthy volunteers (n = 22), patients with benign nodules (n = 19) and malignant nodules (n = 22) were measured by SERS. The spectral analysis results demonstrate that biomolecules in serum, such as amino acids, adenine and nucleic acid bases, change differently due to the different progression of nodules. By further combining with partial least square analysis and linear discriminant analysis (PLS-LDA) method, diagnostic accuracies of 93.65% and 82.93%, sensitivities of 92.68% and 81.82% and specificities of 95.45% and 84.21% can be achieved for differentiating healthy versus thyroid nodular groups and benign versus malignant groups, respectively. The above results have suggested that the blood serum SERS technique is helpful for precise diagnosis and timely treatment for patients with thyroid nodules.


Subject(s)
Spectrum Analysis, Raman , Thyroid Nodule/blood , Thyroid Nodule/diagnostic imaging , Adult , Colloids/chemistry , Discriminant Analysis , Female , Humans , Least-Squares Analysis , Principal Component Analysis , ROC Curve , Silver/chemistry
11.
J Dairy Sci ; 104(4): 4084-4093, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33589256

ABSTRACT

With the purpose of developing an alternative set yogurt with high consumer acceptability, passion fruit juice, at levels that varied from 0 to 10%, was incorporated into set yogurt, and the effects on the fermentation kinetics, physicochemical properties, and functionality of set yogurt were evaluated. The results showed that the addition of passion fruit juice was simultaneously propitious for milk acidification in earlier fermentation stages and reduced the fermentation rate at later stages of fermentation. The phenolic compounds and pectin in passion fruit juice interacted with caseins to form soluble complexes, enhancing the gel strength of set yogurts by 7.5%. The aroma and flavor of the set yogurt was improved as well. However, with the addition of 10% passion fruit juice, the gel structure was destroyed, and the quality of the set yogurt was very degraded. More importantly, the addition of passion fruit juice increased the polyphenol content and significantly enhanced the antioxidant activity of the set yogurt. This investigation demonstrated the feasibility of fabricating passion fruit juice-enriched set yogurt and its superior quality compared with the corresponding normal product.


Subject(s)
Fruit and Vegetable Juices , Yogurt , Animals , Fermentation , Kinetics , Taste
12.
Int J Mol Sci ; 22(13)2021 Jun 23.
Article in English | MEDLINE | ID: mdl-34201771

ABSTRACT

GM2 gangliosidosis disorders are a group of neurodegenerative diseases that result from a functional deficiency of the enzyme ß-hexosaminidase A (HexA). HexA consists of an α- and ß-subunit; a deficiency in either subunit results in Tay-Sachs Disease (TSD) or Sandhoff Disease (SD), respectively. Viral vector gene transfer is viewed as a potential method of treating these diseases. A recently constructed isoenzyme to HexA, called HexM, has the ability to effectively catabolize GM2 gangliosides in vivo. Previous gene transfer studies have revealed that the scAAV9-HEXM treatment can improve survival in the murine SD model. However, it is speculated that this treatment could elicit an immune response to the carrier capsid and "non-self"-expressed transgene. This study was designed to assess the immunocompetence of TSD and SD mice, and test the immune response to the scAAV9-HEXM gene transfer. HexM vector-treated mice developed a significant anti-HexM T cell response and antibody response. This study confirms that TSD and SD mouse models are immunocompetent, and that gene transfer expression can create an immune response in these mice. These mouse models could be utilized for investigating methods of mitigating immune responses to gene transfer-expressed "non-self" proteins, and potentially improve treatment efficacy.


Subject(s)
Dependovirus/genetics , G(M2) Ganglioside/metabolism , Genetic Vectors/administration & dosage , Immunity/immunology , Sandhoff Disease/immunology , Tay-Sachs Disease/immunology , beta-Hexosaminidase alpha Chain/genetics , Animals , Disease Models, Animal , Female , Genetic Therapy , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Sandhoff Disease/genetics , Sandhoff Disease/therapy , Tay-Sachs Disease/genetics , Tay-Sachs Disease/therapy
13.
J Cell Biochem ; 121(1): 70-80, 2020 01.
Article in English | MEDLINE | ID: mdl-31074095

ABSTRACT

Numbers of emerging evidence suggest that variable microRNA (miRNA) expression facilitates the aging process. In this study, we distinguished aberrant miRNA expression in aged skin and explored the biological functions and potential mechanism of upregulated miR-302b-3p. At first, miRNA microarray analysis was examined to explore miRNA expression profiling in the skin of aging mice model by D-galactose (d-gal) injection. We identified 29 aberrant miRNAs in aged mice skin. Next, KEGG enrichment analysis was conducted with DIANA-miPath v3.0, which was revealed that enrichment pathways involved in such processes as extracellular matrix-receptor interaction, MAPK signaling pathway, and mammalian target of rapamycin (mTOR) signaling pathway. The target genes of deregulated miRNAs were predicted from four bioinformatic algorithms (miRDB, Targetscan, miRwalk, and Tarbase). The interaction network of miRNAs and their targets were visualized using Cytoscape software. As a result, we found that some hub genes (including JNK2, AKT1/2/3, PAK7, TRPS1, BCL2L11, and IKZF2) were targeted by 12 potential miRNAs (including miR-302b-3p, miR-291a-5p, miR-139-3p, miR-467c-3p, miR-186-3p, etc.). Subsequently, we identified five upregulated miRNA via quantitative polymerase chain reaction and all of them were confirmed increased significantly in aged skin tissues compared with young control tissues. Among them, high expression of miR-302b-3p was verified in both aged skin tissues and senescence fibroblasts. Furthermore, miR-302b-3p mimic accelerated skin fibroblast senescence and suppressed the longevity-associated gene Sirtuin 1(Sirt1) expression, whereas miR-302b-3p inhibitor could delay skin fibroblast senescence and contribute Sirt1 expression. In addition, we demonstrated that c-Jun N-terminal kinase 2(JNK2) is a direct target of miR-302b-3p by a luciferase reporter assay. An inverse correlation was verified in fibroblasts between miR-302b-3p and JNK2. Most importantly, siRNA JNK2 confirmed that low expression of JNK2 could accelerate fibroblasts senescence. In conclusion, our results indicated that overexpressed miR-302b-3p plays an important biological role in accelerating skin aging process via directly targeting JNK2 gene.


Subject(s)
Cellular Senescence , Fibroblasts/cytology , MicroRNAs/metabolism , Skin/cytology , Algorithms , Animals , Computational Biology , Down-Regulation , Female , Galactose/metabolism , Gene Expression Profiling , Gene Regulatory Networks , MAP Kinase Signaling System , Mice , Mice, Inbred BALB C , Mitogen-Activated Protein Kinase 9/metabolism , Signal Transduction , Sirtuin 1/metabolism , Software , TOR Serine-Threonine Kinases/metabolism
14.
Breast Cancer Res Treat ; 180(2): 481-490, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32056055

ABSTRACT

PURPOSE: Breast cancer is a major public health concern worldwide and shows significant heterogeneity between male and female. Knowing the global incidence landscape in both sexes is critical for the breast cancer prevention and the reduction in disease burden. METHODS: We retrieved the incidence data of breast cancer in both sexes from the Global Burden of Disease 2017 database. Average annual percentage change was used to quantify the temporal trends of breast cancer incidence. RESULTS: Between 1990 and 2017, the number of newly diagnosed female breast cancer (FBC) cases increased from 870.2 thousand to 1937.6 thousand, with the age-standardized incidence rate (ASR) significantly increased from 39.2/100,000 to 45.9/100,000. A total of 166 countries experienced a significant increase in FBC-ASR. The most pronounced increase was mainly found in developing countries. The decrease was mostly detected in several developed countries, such as the USA and the UK. Male breast cancer (MBC) is a rare carcinoma and has no evident cluster across the world. Worldwide, the number of newly diagnosed MBC cases increased from 8.5 thousand in 1990 to 23.1 thousand in 2017, with the ASR significantly increased from 0.46/100,000 to 0.61/100,000. A total of 123 countries showed a significant increasing trend in MBC-ASR. CONCLUSIONS: Breast cancer incidence rates are increasing in most countries in both sexes, although the epidemiological features were not completely shared between FBC and MBC. More emphases should be placed on breast cancer primary prevention and the prevention strategies might need to be tailored for both FBC and MBC.


Subject(s)
Breast Neoplasms/epidemiology , Developed Countries/statistics & numerical data , Developing Countries/statistics & numerical data , Global Burden of Disease/trends , International Agencies/organization & administration , Registries/statistics & numerical data , Adolescent , Adult , Aged , Breast Neoplasms/classification , Breast Neoplasms/diagnosis , Female , Global Burden of Disease/statistics & numerical data , Humans , Incidence , Male , Middle Aged , Young Adult
15.
Anal Chem ; 91(13): 8154-8161, 2019 07 02.
Article in English | MEDLINE | ID: mdl-31140784

ABSTRACT

Aristolochic acids (AAs) contained in herbal plants are implicated in multiple organ injuries and have a high mutational burden in upper tract urothelial cancers. The currently available techniques for monitoring AAs include LC (liquid chromatography) and LC/MS (mass spectrometry), but the application of these approaches are limited due to the complex sample preparation and derivatization steps. Therefore, there is an urgent need to develop efficient methods for identifying and quantifying AAs. Here, we present a new dual-spectroscopic approach for the direct detection of AAs from blood and tissue samples; the detection of aristolochic acid I (AAI) is performed by surface-enhanced Raman spectroscopy (SERS), and its bioproduct, aristololactam (AAT), is detected by fluorescence spectroscopy based on their distinctive spectral response. Furthermore, a graphene assisted enrichment coupled with a magnetic retrieval strategy was developed to enhance SERS sensitivity toward AAI. Our method was successfully applied to directly determine both AAI and AAT from the blood, liver, and kidney of rats. The potential for real-world application was demonstrated by continuously monitoring AAI and AAT in rat blood and tissues after AAI feeding. The results showed that AAI was gradually metabolized to AAT and transported to different organs. It was found that the metabolism of AAI took place in the kidney, but AAT residue was detected in both liver and kidney, which might be related to long-term toxicity and gene mutation. The proposed dual-spectroscopic strategy is applicable to long-term toxicology research and to the direct diagnosis of AAI-induced organ injury.


Subject(s)
Aristolochic Acids/pharmacokinetics , Spectrometry, Fluorescence/methods , Spectrum Analysis, Raman/methods , Animals , Aristolochic Acids/blood , Kidney/metabolism , Liver/metabolism , Male , Models, Molecular , Rats, Sprague-Dawley , Tissue Distribution
16.
Bioconjug Chem ; 29(4): 1251-1260, 2018 04 18.
Article in English | MEDLINE | ID: mdl-29528624

ABSTRACT

The number and spacing of B-cell epitopes on antigens have a profound impact on the activation of B cells and elicitation of antibody responses, the quantitative aspects of which may be utilized for rational design of vaccines. Ni-chelating liposomes have been widely used as protein carriers in experimental studies of vaccine delivery, owing to the convenience and versatility of this conjugation chemistry. However, the epitope number per particle as well as the stability of protein conjugation on liposomes remain far less characterized. Here we have developed quantitative methods to measure the average spatial density of proteins on liposomes using both ensemble and single-molecule techniques and demonstrated their utility using liposomes conjugated with native proteins of two different sizes. These studies revealed that the initial density of protein conjugation on Ni-chelating liposomes can be finely controlled, but the density can decrease over time upon dilution due to the noncovalent nature of Ni-chelation chemistry. These results indicate that an alternative method other than the Ni-chelation chemistry is needed for stable conjugation of epitopes onto liposomes and also suggest a general strategy that can be used to precisely regulate the epitope density on liposomes for B-cell antigen delivery.


Subject(s)
Bacterial Proteins/chemistry , Chelating Agents/chemistry , Liposomes/chemistry , Luminescent Proteins/chemistry , Nickel/chemistry , Epitopes/chemistry , Protein Domains , Protein Stability , Recombinant Proteins/chemistry , Surface Properties
17.
Biochem Biophys Res Commun ; 482(4): 1437-1442, 2017 Jan 22.
Article in English | MEDLINE | ID: mdl-27965093

ABSTRACT

HIV-1 Gag protein is the major structural protein for the assembly of virion particles. Although studies have been carried out using partially purified Gag proteins to investigate the mechanisms of viral particle assembly, the outcomes of an assembly reaction remain controversial. Here we have developed an improved procedure for purification of several untagged retroviral Gag proteins from E. coli to more than 95% purity and characterized Gag assembly in solution. We found that HIV-1 Gag proteins can undergo nucleic acid-dependent aggregation with several unexpected features: (1) they form spherical particles that are as large as microns in diameter; (2) the size of the aggregates vary with the molar ratio between nucleic acids and proteins, with the average size of these particles reaching maximal at a molar ratio of 1:2 between nucleic acids and proteins; and (3) these particles can be efficiently disassembled simply upon addition of excess nucleic acids into the solution, suggesting the presence of an ordered assembly. Single-stranded DNA oligos that are 10 nucleotides or shorter do not support the formation of these particles. Furthermore, the matrix domain of the Gag protein dramatically facilitates the formation of these aggregates. These studies uncover a previously uncharacterized pathway of HIV Gag assembly in vitro, and have implications for HIV-1 Gag assembly and pathogenesis in vivo.


Subject(s)
HIV-1/physiology , Nucleic Acids/metabolism , gag Gene Products, Human Immunodeficiency Virus/metabolism , Cell Death , DNA/analysis , DNA, Single-Stranded/metabolism , Electrophoresis, Polyacrylamide Gel , Escherichia coli/metabolism , Flow Cytometry , Hydrogen-Ion Concentration , Microscopy, Electron , Nucleotides/metabolism , RNA, Transfer/metabolism , Temperature , Virion/metabolism , Virus Assembly
18.
Am J Physiol Regul Integr Comp Physiol ; 312(5): R671-R680, 2017 05 01.
Article in English | MEDLINE | ID: mdl-28148493

ABSTRACT

Cytochrome c oxidase (COX) subunit 4 has two paralogs in most vertebrates. The mammalian COX4-2 gene is hypoxia responsive, and the protein has a disrupted ATP-binding site that confers kinetic properties on COX that distinguish it from COX4-1. The structure-function of COX4-2 orthologs in other vertebrates remains uncertain. Phylogenetic analyses suggest the two paralogs arose in basal vertebrates, but COX4-2 orthologs diverged faster than COX4-1 orthologs. COX4-1/4-2 protein levels in tilapia tracked mRNA levels across tissues, and did not change in hypoxia, arguing against a role for differential post-translational regulation of paralogs. The heart, and to a lesser extent the brain, showed a size-dependent shift from COX4-1 to COX4-2 (transcript and protein). ATP allosterically inhibited both velocity and affinity for oxygen in COX assayed from both muscle (predominantly COX4-2) and gill (predominantly COX4-1). We saw some evidence of cellular and subcellular discrimination of COX4 paralogs in heart. In cardiac ventricle, some non-cardiomyocyte cells were COX positive but lacked detectible COX4-2. Within heart, the two proteins partitioned to different mitochondrial subpopulations. Cardiac subsarcolemmal mitochondria had mostly COX4-1 and intermyofibrillar mitochondria had mostly COX4-2. Collectively, these data argue that, despite common evolutionary origins, COX4-2 orthologs of fish show unique patterns of subfunctionalization with respect to transcriptional and posttranslation regulation relative to the rodents and primates that have been studied to date.


Subject(s)
Electron Transport Complex IV/genetics , Electron Transport Complex IV/metabolism , Gene Expression Regulation, Enzymologic/genetics , Tilapia/genetics , Tilapia/metabolism , Animals , Humans , Isoenzymes , Mice , Organ Specificity/genetics , Rats , Sequence Homology , Species Specificity , Tissue Distribution/genetics , Transcriptional Activation/genetics
20.
Crit Rev Biotechnol ; 34(1): 56-76, 2014 Mar.
Article in English | MEDLINE | ID: mdl-23883072

ABSTRACT

Flowering is the most elusive and fascinating of all plant developmental processes. The ability to induce flowering in vitro in orchids would reduce the relatively long juvenile phase and provide deeper insight into the physiological, genetic and molecular aspects of flowering. This review synthesizes all available studies that have been conducted on in vitro flowering of orchids with the objective of providing valuable clues as to the mechanism(s) that is possibly taking place.


Subject(s)
Flowers , Orchidaceae , Tissue Culture Techniques , Models, Biological
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