scholarly journals Tetracycline-regulated expression enables purification and functional analysis of recombinant connexin channels from mammalian cells

2004 ◽  
Vol 383 (1) ◽  
pp. 111-119 ◽  
Author(s):  
Irina V. KOREEN ◽  
Wafaa A. ELSAYED ◽  
Yu J. LIU ◽  
Andrew L. HARRIS
Keyword(s):  
Mammalian Cells ◽  
Cultured Cells ◽  
Expression System ◽  
Physiological Processes ◽  
Messenger Molecules ◽  
One Step ◽  
Cellular Control

Intercellular coupling mediated by gap junction channels composed of connexin protein underlies numerous physiological processes, such as cellular differentiation, tissue synchronization and metabolic homoeostasis. The distinct molecular permeability of junctional channels composed of different connexin isoforms allows cellular control of coupling via regulation of isoform expression. However, the permeability properties of most connexin isoforms have not been well characterized due to the difficulty of manipulating and measuring the diffusible concentrations of cytoplasmic messenger molecules and metabolites, and to a lack of control over channel isoform composition, in vivo. Here we present a method to express and purify active connexin hemichannels of a single isoform or a consistent ratio of two isoforms from cultured cells using the Tet-On inducible expression system and one-step anti-haemagglutinin immunoaffinity purification. The procedure yields 10–20 μg of pure connexin protein from 2.5×108 HeLa cells. The purified channels are shown to be useful for in vitro permeability analysis using well established techniques. This method has substantial advantages over existing methods for heterologous connexin expression, such as the ease of co-expression of two isoforms at a constant ratio, consistently high expression levels over many passages, and the ability to study channel properties in situ as well as in purified form. Furthermore, the generic cloning site of the new pBI-GT vector and the commercial availability of anti-haemagglutinin (clone HA-7)–agarose make this affinity tagging and purification procedure easily applicable to other proteins.

In situ synthesis of NIR-light emitting carbon dots derived from spinach for bio-imaging applications

2017 ◽  
Vol 5 (35) ◽  
pp. 7328-7334 ◽  
Author(s):  
Liping Li ◽  
Ruiping Zhang ◽  
Chunxiang Lu ◽  
Jinghua Sun ◽  
Lingjie Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
In Situ Synthesis ◽  
Light Emitting ◽  
Nir Light ◽  
Bio Imaging ◽  
One Step

NIR-light emitting CDs (R-CDs) were prepared using spinach as a precursor by one-step solvothermal treatment. The R-CDs exhibited great optical properties, negligible toxicity, and superior labelling capability both in vitro and in vivo.

Immobilization and neutralization of Treponema pallidum attached to cultured mammalian cells

1985 ◽  
Vol 31 (12) ◽  
pp. 1152-1156
Author(s):  
Thomas Fitzgerald
Keyword(s):  
Mammalian Cells ◽  
Neutralizing Antibodies ◽  
Cultured Cells ◽  
Treponema Pallidum ◽  
Immune Serum ◽  
Immune Reactivity ◽  
Complex Environment ◽  
In Vitro Effects

The in vitro effects of antibodies, complement, and (or) macrophages on Treponema pallidum have been previously characterized using relatively simple systems of organisms incubated with the immune components. In vivo, the more complex environment may alter immune reactivity. Experiments were performed to determine whether immobilizing and neutralizing antibodies retained their effectiveness in a more complex environment involving cultured mammalian cells. Two different protocols were used. In protocol A treponemes and normal or immune serum were mixed and added immediately to the cultured cells. In protocol B treponemes were preincubated for 18 h with cultured cells to maximize treponemal attachment; then normal or immune serum was added. With both protocols, attachment of organisms resulted in less effecient immobilization and neutralization. In further experiments, cultured cells were disrupted with Triton X, leaving cytoskeletal remnants on the vessel surface. Identical immobilization and neutralization experiments were performed in the presence of these remnants. In contrast to the findings with viable cultured cells, treponemal attachment to these nonviable remnants did not effect either antibody reaction. Attached organisms were immobilized or neutralized just as efficiently as unattached organisms. Results are discussed in terms of the altered immune reactivity in more complex in vitro environments.

scholarly journals Antimicrobial and Chemoattractant Activity, Lipopolysaccharide Neutralization, Cytotoxicity, and Inhibition by Serum of Analogs of Human Cathelicidin LL-37

2005 ◽  
Vol 49 (7) ◽  
pp. 2845-2850 ◽  
Author(s):  
Cristina D. Ciornei ◽  
Thorgerdur Sigurdardóttir ◽  
Artur Schmidtchen ◽  
Mikael Bodelsson
Keyword(s):  
Amino Acids ◽  
Mammalian Cells ◽  
Cultured Cells ◽  
Antimicrobial Properties ◽  
Neutrophil Granulocytes ◽  
Beneficial Effects ◽  
Hydrophobic Amino Acids ◽  
Conventional Antibiotics

ABSTRACT Antimicrobial peptides have been evaluated in vitro and in vivo as alternatives to conventional antibiotics. Apart from being antimicrobial, the native human cathelicidin-derived peptide LL-37 (amino acids [aa] 104 to 140 of the human cathelicidin antimicrobial peptide) also binds and neutralizes bacterial lipopolysaccharide (LPS) and might therefore have beneficial effects in the treatment of septic shock. However, clinical trials have been hampered by indications of toxic effects of LL-37 on mammalian cells and evidence that its antimicrobial effects are inhibited by serum. For the present study, LL-37 was compared to two less hydrophobic fragments obtained by N-terminal truncation, named 106 (aa 106 to 140) and 110 (aa 110 to 140), and to a previously described more hydrophobic variant, the 18-mer LLKKK, concerning antimicrobial properties, lipopolysaccharide neutralization, toxicity against human erythrocytes and cultured vascular smooth muscle cells, chemotactic activity, and inhibition by serum. LL-37, fragments 106 and 110, and the 18-mer LLKKK inhibited the growth of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans in a radial diffusion assay, inhibited lipopolysaccharide-induced vascular nitric oxide production, and attracted neutrophil granulocytes similarly. While fragments 106 and 110 caused less hemolysis and DNA fragmentation in cultured cells than did LL-37, the 18-mer LLKKK induced severe hemolysis. The antibacterial effect of fragments 106 and 110 was not affected by serum, while the effect of LL-37 was reduced. We concluded that the removal of N-terminal hydrophobic amino acids from LL-37 decreases its cytotoxicity as well as its inhibition by serum without negatively affecting its antimicrobial or LPS-neutralizing action. Such LL-37-derived peptides may thus be beneficial for the treatment of patients with sepsis.

In-vitro and in-vivo consequences of mutations in the von Willebrand factor cleaving protease ADAMTS13 in thrombotic thrombocytopenic purpura

2006 ◽  
Vol 96 (10) ◽  
pp. 454-464 ◽  
Author(s):  
Roberta Donadelli ◽  
Federica Banterla ◽  
Miriam Galbusera ◽  
Cristina Capoferri ◽  
Sara Bucchioni ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand Factor ◽  
Protease Activity ◽  
Mammalian Cells ◽  
Expression System ◽  
Thrombocytopenic Purpura ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThrombotic thrombocytopenic purpura (TTP) is a disease characterized by microvascular thrombosis, often associated with deficiency of the von Willebrand factor (VWF) cleaving protease ADAMTS13.We investigated the spectrum of ADAMTS13 gene mutations in patients with TTP and congenital ADAMTS13 deficiency to establish the consequences on ADAMTS13 processing and activity. We describe five missense (V88M, G1239V, R1060W, R1123C and R1219W), 1 nonsense (W1016Stop) and 1 insertion (82_83insT) mutations. In two patients no mutation was identified despite undetectable protease activity. Expression in HEK293 mammalian cells (V88M, G1239V, R1123C and R1219W) documented that three missense mutants were not secreted, whereas theV88M was secreted at low levels and with reduced activity. We also provide evidence that impaired secretion of ADAMTS13 mutants observed in vitro translates into severely reduced ADAMTS13 antigen levels in patients in vivo. To evaluate whether the small amounts of mutant protease present in the circulation of patients had VWF cleaving activity, WT and mutant rADAMTS13 were stably expressed in Drosophila S2 cells under the influence of the Drosophila BiP protein signal sequence, which allows protein secretion. Drosophila expression system showed a 40–60% protease activity in the mutants. Several single nucleotide polymorphisms (SNPs) within exons and intron boundaries were found in patients, suggesting that the interplay of SNPs could at least in part account for ADAMTS13 functional abnormalities in patients without mutations. In conclusion, defective secretion and impaired activity of the mutants concur to determine an almost complete deficiency of ADAMTS13 activity in patients with a homozygous or two heterozygous ADAMTS13 mutations.

scholarly journals Development of SpyTag/SpyCatcher-Bacmid Expression Vector System (SpyBEVS) for Protein Bioconjugations Inside of Silkworms

2019 ◽  
Vol 20 (17) ◽  
pp. 4228 ◽  
Author(s):  
Jian Xu ◽  
Tatsuya Kato ◽  
Enoch Y. Park
Keyword(s):  
Expression System ◽  
Vector System ◽  
Proof Of Concept ◽  
Silkworm Larvae ◽  
Protein Partners ◽  
Split Protein ◽  
One Step ◽  
And Function

Protein conjugations at post-translational levels are known to be essential to protein stability and function. Recently, it has been proven that the split protein CnaB2 (SpyTag/SpyCatcher, ST/SC) from Streptococcus pyogenes can induce covalent conjugation rapidly and efficiently under various conditions. The protein of interest fused with the split protein SC/ST could be assembled spontaneously. In light of this finding, we introduced the ST/SC protein coupling concept into the silkworm-bacmid protein expression system (SpyBEVS). As a proof of concept, we first examined and confirmed that a competent ligation occurred between ST/SC-fused protein partners in vitro in cultured silkworm cells and in vivo in silkworm larvae by co-infection of several recombinant baculoviruses. The protein conjugation could be also achieved sufficiently by a simple one-step mixture of purified ST/SC-tagged peptide-protein pairs in vitro. Given the flexibility and robustness of silkworm-BEVS, our results on SpyBEVS show an alternative method for enabling the production of protein decorations in vitro and inside of silkworms.

scholarly journals Near-Infrared Genetically Encoded Positive Calcium Indicator Based on GAF-FP Bacterial Phytochrome

2019 ◽  
Vol 20 (14) ◽  
pp. 3488 ◽  
Author(s):  
Oksana M. Subach ◽  
Natalia V. Barykina ◽  
Konstantin V. Anokhin ◽  
Kiryl D. Piatkevich ◽  
Fedor V. Subach
Keyword(s):  
Calcium Ions ◽  
Mammalian Cells ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Dynamic Range ◽  
Cultured Cells ◽  
Infrared Region ◽  
Calcium Indicator

A variety of genetically encoded calcium indicators are currently available for visualization of calcium dynamics in cultured cells and in vivo. Only one of them, called NIR-GECO1, exhibits fluorescence in the near-infrared region of the spectrum. NIR-GECO1 is engineered based on the near-infrared fluorescent protein mIFP derived from bacterial phytochromes. However, NIR-GECO1 has an inverted response to calcium ions and its excitation spectrum is not optimal for the commonly used 640 nm lasers. Using small near-infrared bacterial phytochrome GAF-FP and calmodulin/M13-peptide pair, we developed a near-infrared calcium indicator called GAF-CaMP2. In vitro, GAF-CaMP2 showed a positive response of 78% and high affinity (Kd of 466 nM) to the calcium ions. It had excitation and emission maxima at 642 and 674 nm, respectively. GAF-CaMP2 had a 2.0-fold lower brightness, 5.5-fold faster maturation and lower pH stability compared to GAF-FP in vitro. GAF-CaMP2 showed 2.9-fold higher photostability than smURFP protein. The GAF-CaMP2 fusion with sfGFP demonstrated a ratiometric response with a dynamic range of 169% when expressed in the cytosol of mammalian cells in culture. Finally, we successfully applied the ratiometric version of GAF-CaMP2 for the simultaneous visualization of calcium transients in three organelles of mammalian cells using four-color fluorescence microscopy.

In Situ One-Step Fluorescence Labeling Strategy of Exosomes via Bioorthogonal Click Chemistry for Real-Time Exosome Tracking In Vitro and In Vivo

2020 ◽  
Vol 31 (5) ◽  
pp. 1562-1574 ◽  
Author(s):  
Sukyung Song ◽  
Man Kyu Shim ◽  
Seungho Lim ◽  
Yujeong Moon ◽  
Suah Yang ◽  
...  
Keyword(s):  
Click Chemistry ◽  
Real Time ◽  
Fluorescence Labeling ◽  
One Step

scholarly journals Establishing F1A-CreERT2 Mice to Trace Fgf1 Expression in Adult Mouse Cardiomyocytes

Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 121
Author(s):  
Yi-Chao Hsu ◽  
Yu-Fen Chung ◽  
Mei-Shu Chen ◽  
Chi-Kuang Wang ◽  
Si-Tse Jiang ◽  
...  
Keyword(s):  
Troponin T ◽  
Lineage Tracing ◽  
Mouse Line ◽  
Protein Coding ◽  
Physiological Processes ◽  
Mrna Variants ◽  
Alternatively Spliced

Fibroblast growth factor 1 (FGF1) regulates many biological and physiological processes. In mice, Fgf1 gene contains at least three upstream promoters and are alternatively spliced to the first protein coding exon, giving rise to different Fgf1 mRNA variants (1A, 1B and 1G). Among them, the Fgf1A transcript is predominantly expressed in the heart. FGF1 can induce cardiomyocyte regeneration and cardiogenesis in vitro and in vivo. Here, we generated a novel mouse line using the Fgf1A promoter (F1A) driving the expression of the inducible Cre recombinase (CreERT2). We firstly demonstrated that the highest mRNA expression of CreERT2 were detected in the heart specifically of F1A-CreERT2 mice, similar to that of Fgf1A mRNA. The F1A-CreERT2 mice were crossed with ROSA26 mice, and the F1 mice were analyzed. The LacZ-positive signals were detected exclusively in the heart after tamoxifen administration. The CreERT2-mediated recombination in the tissues is monitored through LacZ-positive signals, indicating the in situ localization of F1A-positive cells. Consistently, these F1A-positive cells with RFP-positive signals or LacZ-positive blue signals were co-localized with cardiomyocytes expressing cardiac troponin T, suggesting cardiomyocyte-specific activation of Fgf1A promoter. Our data suggested that the F1A-CreERT2 mouse line could be used for time-dependent and lineage tracing of Fgf1A-expressing cells in vivo.

scholarly journals Differences in decorin expression by papillary and reticular fibroblasts in vivo and in vitro

1993 ◽  
Vol 290 (3) ◽  
pp. 893-899 ◽  
Author(s):  
E Schönherr ◽  
L A Beavan ◽  
H Hausser ◽  
H Kresse ◽  
L A Culp
Keyword(s):  
In Situ Hybridization ◽  
Cultured Cells ◽  
Chondroitin Sulphate ◽  
Cell Types ◽  
Specific Pattern ◽  
Dermatan Sulphate ◽  
Sulphate Proteoglycan

Immunostaining of adult human skin shows that the small dermatan sulphate proteoglycan decorin is abundant in the whole dermal layer but absent from the epidermis. In the papillary layer adjacent to the dermal-epidermal border, more decorin was detected than in the reticular layer of the dermis. Expression of decorin mRNA by cells in the papillary dermis could also be shown by in situ hybridization. In contrast, biglycan, another small chondroitin sulphate/dermatan sulphate proteoglycan, is found only at the dermal-epidermal border. Therefore the biosynthesis of these two proteoglycans by papillary and reticular fibroblasts from two different donors was compared in tissue culture. Papillary fibroblasts secrete up to 5.9 times more decorin than reticular fibroblasts, while the amounts of cell-associated decorin in both cell types are similar. By Northern blot analysis as well as by in situ hybridization it was shown that papillary fibroblasts contain more mRNA coding for decorin than do reticular cells. In addition, no mosaic pattern of decorin expression was found in the cultured cells. The expression and synthesis of biglycan compared with decorin was about 10 times lower and did not show any significant differences for the two cells types. The kinetics of secretion and the rate of endocytosis of decorin were similar for both types of fibroblasts. These results were found with fibroblasts between the 9th and 15th passage from a newborn subject as well as from a 78-year-old donor, indicating that the pattern of decorin synthesis is not age-dependent in the range investigated. These results further show that fibroblasts from different layers of the dermis have a specific pattern of synthesis of small chondroitin sulphate/dermatan sulphate proteoglycans, and they also maintain these patterns in cell culture.

scholarly journals Lentivirus-mediated long-term overexpression of specific microRNA for complementary miRNA pairs in mammalian cells

2019 ◽  
Author(s):  
Shupei Qiao ◽  
Yufang Zhao ◽  
Kai Li ◽  
Yulu Sun ◽  
Liuke Sun ◽  
...  
Keyword(s):  
Mirna Expression ◽  
Mammalian Cells ◽  
Expression System ◽  
Seed Region ◽  
Future Studies ◽  
Mirna Degradation ◽  
Mirna Seed

AbstractThe establishment of a method that would overexpress or suppress of specific microRNA activity is essential for the functional analysis of these molecules and for the development of miRNA therapeutic applications. There already exist excellent ways to inhibit miRNA function in vitro and in vivo by overexpressing miRNA target sequences, which include miRNA ‘decoys’, ‘sponges’, or ‘antagomirs’ that are complementary to an miRNA seed region. Conversely, no methods to induce stable gain-of-function phenotypes for specific miRNAs have, as yet, been reported. Furthermore, the discovery of complementary miRNA pairs raises suspicion regarding the existing methods used for miRNA overexpression. In our study, we will study whether the traditional methods for miRNA overexpression can be used for specific miRNA overexpression while complementary miRNA pairs exist. In addition, we test various miRNA-expression cassettes that were designed to efficiently overexpress specific miRNA through the shRNA lentivirus expression system. We report the optimal conditions that were established for the design of such miRNA-expression cassettes. We finally demonstrate that the miRNA-expression cassettes achieve efficient and long-term overexpression of specific miRNAs. Meanwhile, our results also support the notion that miRNA–miRNA interactions are implicated in potential, mutual regulatory patterns and beyond the seed sequence of miRNA, extensive pairing interactions between a miRNA and its target also lead to target-directed miRNA degradation. Our results indicate that our method offers a simple and efficient means to over-express the specific miRNA with long-term which will be very useful for future studies in miRNA biology, as well as contributed to the development of miRNA-based therapy for clinical applications.

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