Construction and application of mCherry red fluorescent protein fusion expression system in lactic acid bacteria / 生物工程学报

In order to enrich the library of domestic research about new red fluorescent marker in lactic acid bacteria (LAB), we described a new fusion expression system in Lactobacillus plantarum WCFS1 based on the pSIP vector. This system contained red fluorescent protein mCherry as a marker and bile salt hydrolase gene (bsh) as a reporter gene. Moreover, in this study, four different promoters (PsppA, PldhL, P32 and PslpA) were used to regulate the expression of the fusion protein mCherry-BSH, completing the inducible and constitutive expression in lactic acid bacteria. The recombinant protein mCherry-BSH presented activity of red fluorescence and bile salt hydrolase (BSH). The successful construction of the fusion expression system in LAB using a red fluorescent protein mCherry provides favorable conditions for the distribution, intestinal colonization and survival rate of lactic acid bacteria, so as to reveal the function mechanism of its probiotic characteristics; and the system also could lay the foundation for researches on protein expression, cellular localization and properties identification of active protein in lactic acid bacteria.

Screening efficient constitutive promoters in Corynebacterium glutamicum based on time-series transcriptome analysis / 生物工程学报

Promoter, an essential regulatory element, is widely used for metabolic engineering of industrial strains. Corynebacterium glutamicum is an important industrial workhorse to produce various amino acids. However, strong constitutive promoters that are applicable to C. glutamicum are rarely reported. In this study, we first performed a time-series transcriptome analysis of a glutamate hyper-producing strain C. glutamicum SL4 by using RNA-Seq. Overall, we picked 10 samples at different time during the fermentation process. By analyzing the time-series transcriptome data, we selected 10 candidate genes with the highest transcriptional level. These genes were all transcribed stably during the fermentation process. We subsequently cloned the promoter sequences and evaluated the promoters' strength in strain SL4 using a red fluorescent protein reporter system. To evaluate the universality of the promoters in different C. glutamicum strains, we further tested the performance of some promoters in wild type C. glutamicum strains, including ATCC 13869 and ATCC 13032. The strongest promoter was further characterized using LacZ as a reporter in all the three C. glutamicum strains. Finally, we successfully obtained three constitutive promoters with universality, PcysK, PgapA and PfumC. PcysK is the most efficient promoter among the three C. glutamicum strains. In strains SL4 and ATCC 13869, the strength of PcysK is 2-fold of the strong inducible promoter Ptac using the red fluorescent protein as a reporter and 4-fold of Ptac using LacZ as a reporter. Moreover, the strength of PcysK reaches 30%-40% of Ptac in strain ATCC 13032. The promoter PcysK is identified as a strong promoter for the first time, which can be used as an efficient biobrick for metabolic engineering of synthesis pathways in C. glutamicum.

Construction of lung tumor cells using RFP and Fluc dual-labeled system / 国际生物医学工程杂志

Objective To establish a human lung cancer cell line that can stably express firefly luciferase (Fluc) and red fluorescent protein (RFP) gene so as to lay the foundation for the further establishment of a live-imaging lung cancer xenograft model in nude mice and therapeutic research.Methods The lentiviral vector pHBLV-FlucRFP containing luciferase and red fluorescent protein was constructed and then transfected into 293T cells for virus packaging.The complete virus was used to infect human lung cancer cell lines A549,H1975 and human B-cell lymphoma cell line K562.The stable cell lines were obtained by puromycin selection.Fluorescence microscopy and quantitative PCR were used to confirm the RFP and Fluc expression.Results The lentiviral vector pHBLV-FlucRFP was successfully constructed.Cancer cell line A549,H1975 and K562 stably expressing Fluc and RFP was obtained.The real-time quantitative PCR results showed that the relative expression of Fluc gene in the three stable infected cells was much higher than that in the corresponding wild-type cells,and the differences were statistically significant(all P＜0.05).Conclusion The human lung cancer cell line A549,H1975 and human B-cell lymphoma cell line K562 with dual expression of RFP and Fluc were obtained,which provided a new model of fluorescent cells for in vivo imaging of immunodeficient mouse models such as nude mice.

Dynamic distribution of calmodulin labeled with red fluorescent protein in the polar growth of Aspergillus fumigatus / 中华皮肤科杂志

Objective To construct a native promoter-regulated Aspergillus fumigatus strain containing red fluorescent protein-labeled calmodulin (CaM-RFP),and to observe the dynamic distribution of calmodulin during the growth of Aspergillus fumigatus.Methods Bilateral flanking sequences of Aspergillus fumigatus calmodulin gene were designed,and plasmids containing the two flanking sequences and mRFP-Aspergillus fumigatus pyrG gene (mRFP-AfpyrG) were amplified separately.The final linear PCR product for transformation was generated from the above three PCR products by fusion PCR.Then,the above linear fragment was transferred into the Aspergillus fumigatus strain by protoplast transformation,so as to construct the CaM-RFP Aspergillus fumigatus strain.The monoclonal colony was picked from the screening medium and subjected to culture.Then,the stablest fluorescent monoxenic strain of Aspergillus fumigatus was selected,and the transformant was verified by PCR.The recombinant strain and wild-type stain were cultured on solid nutrient media separately,and the morphology of these strains was observed by fluorescence microscopy at different time points.Additionally,the above 2 strains were cultured in liquid media separately,and XTT assay was performed to evaluate the growth activity of strains.Microscopy was also conducted to dynamically observe the CaM-RFP Aspergillusfumigatus strain,and analyze the spatial and temporal distribution of calmodulin during the growth and development of Aspergillus fumigatus.Results The fluorescent phenotype and PCR identification results both indicated the successful construction of the CaM-RFP Aspergillus fumigatus strain.The growth activity at 24 hours did not differ between the recombinant strain and wild-type stain (A490:0.689 ± 0.081 vs.0.678 ± 0.054,t =1.32,P ＞0.05),so did the morphology.During the polarized growth of Aspergillus fumigatus,calmodulin was always at the top of the hyphae,germination site of the hyphal branch and the top of new branches.Conclusion Calmodulin may be involved in the regulation of spore germination and polar hyphal growth of Aspergillus fumigatus.

Experimental study of glioma stem cell-mediated immune tolerance in tumor microenvironment / 中华肿瘤杂志

Objective@#To investigate the tumor microenvironment of immune tolerance induced by glioma stem cells (GSC).@*Methods@#Human GSC SU3 cells transfected with red fluorescent protein (SU3-RFP) gene were implanted into the brain, subcutis (armpit and foot), liver and abdominal cavity of transgenic green fluorescence protein (GFP) nude mice to establish RFP+ /GFP+ dual fluorescence solid tumor model. The re-cultured cells derived from implanted tumor tissues, SU3-RFP cells co-cultured with peritoneal fluid of transgenic GFP nude mice and malignant ascites of tumor-bearing mice were observed by fluorescence microscopy and real-time video image tracing to analyze the microenvironment of immune tolerance mediated by RFP+ /GFP+ implanted tumor.@*Results@#Dual fluorescence labeled frozen section showed that all of cells in the tumor microenvironment were GFP+ , while the pressed tissue-patch showed that the tumor blood vessels exhibited a RFP+ /GFP+ double-positioning yellow. In the GFP single fluorescence labeled tumor tissue, all of cells in the microenvironment were green, including tumor edge, necrotic foci and blood vessel. Among them, CD68+ , F4/80+ , CD11c+ , CD11b+ and CD80+ cells were observed. In the dual fluorescence labeled co-cultured cells, the phagocytosis and fusion between green host cells and red tumor cells were also observed, and these fusion cells might transfer to the malignant dendritic cells and macrophages.@*Conclusions@#The tumor microenvironment of immune tolerance induced by GSC is not affected by the tissue types of tumor-inoculated sites, and the immune tolerance mediated by inflammatory cells is associated with the inducible malignant transformation, which may be driven by cell fusion.

Transferencia génica asistida por campos magnéticos: Estudios en células gliales / Magnetic field-assisted gene transfer: Studies in glial cells / Transferência gênica assistida por camposmagnéticos: Estudos em células gliais

Las nanopartículas magnéticas (MNP) complejadas con vectores génicos pueden, en presencia de un campo magnético externo, amplificar sustancialmente la eficiencia de la transferencia génica. Esta técnica, denominada magnetofección, es de gran interés en el campo de la terapia génica. En este estudio se caracterizó la mejora de transferencia génica en células gliales B92 utilizando complejos constituidos por diferentes proporciones de MNP asociadas a dos vectores adenovirales, a saber: los complejos entre las MNP denominadas PEI-Mag2 asociadas al adenovector RAd-GFP que expresa la proteína fluorescente verde GFP o al adenovector RAd-DsRed que expresa la proteína fluorescente roja DsRed2. Se demostró que para ambos vectores, a medida que la relación MNP/partícula viral física (PVF) va aumentando, la amplificación de la transfección también aumenta hasta que se llega a una relación MNP/PVF a partir de la cual el factor de amplificación alcanza un plateau. Se determinó que para el complejo PEI-Mag2/RAd-GFP la relación a partir de la cual se alcanza el plateau es de aproximadamente 0,5 fg Fe/PVF mientras que para el complejo PEI-Mag2/RAd-DsRed, esta relación corresponde a aproximadamente 71 fg Fe/PVF. Se concluye que los dos complejos magnéticos estudiados representan promisorias herramientas para mejorar la eficiencia en la terapia génica en células cerebrales.

It is known that certain types of magnetic nanoparticles (MNPs) complexed to gene vectors can, in the presence of an external magnetic field, greatly enhance gene transfer into cells. This technique, called magnetofection, is of great relevance to gene therapy. In the present study the ability of MNP/adenovector complexes to enhance gene transfer to B92 glial cells was assessed. Two complexes were assessed, namely PEI-Mag2/RAd-GFP and PEI-Mag2/RAd-DsRed, which are constituted by the MNP PEI-Mag2 complexed to the adenovector RAd-GFP (expressing the green fluorescent protein GFP) and RAd-DsRed (expressing the red fluorescent protein DsRed2), respectively. It was shown that for both vectors, an increase in the ratio MNP/PVP (physical viral particle) is paralleled by an increase in transduction efficiency, up to a certain threshold value at which an efficiency plateau is reached. This threshold value was 0.5 fg Fe/PVP for the RAd-GFP complex and about 71 fg Fe/PVP for the RAd-DsRed complex. It can be concluded that both magnetic complexes assessed in this study represent promising tools for enhancing the efficiency of gene therapy in brain cells.

As nanopartículas magnéticas (MNPs) complexadas com vetores de genes podem, em presença de um campo magnético externo, aumentar consideravelmente a eficiência da transferência gênica. Esta técnica, chamada magnetofecção, é de grande relevância para a terapia genética. No presente estudo, foi caracterizada a melhoria de transferência de genes em células gliais B92 utilizando complexos constituídos por diferentes proporções de MNP associadas a dois vetores adenovirais, a saber: os complexos entre as MNP denominadas PEI-Mag2 associadas ao adenovetor RAd-GFP que expressa a proteína fluorescente verde GFP ou ao adenovetor RAd-DsRed que expressa a proteína fluorescente vermelha DsRed2. Foi demonstrado que para ambos os vetores, enquanto a relação MNP/partícula viral física (PVF) vai aumentando, a amplificação da transfecção também aumenta até que se chega a uma relação MNP/PVF a partir da qual o fator de amplificação alcança um limiar. Determinou-se que para o complexo PEI-Mag2/RAd-GFP a relação a partir da qual se atinge o limiar é de aproximadamente 0,5 fg Fe/PVF ao passo que para o complexo PEI-Mag2/RAd-DsRed, esta relação corresponde a aproximadamente 71 fg Fe/PVF. Conclui-se que os dois complexos magnéticos estudados representam promissoras ferramentas para melhorar a eficiência na terapia de genes em células cerebrais.

Application of dual-color tagging strategy with GFP/RFP in tumor cell imaging / 肿瘤研究与临床

Imaging with fluorescent proteins has been revolutionary and has led to the new field of cell biology in vivo.Many new applications of this technology have been developed in recent years.Multicolor imaging technique of fluorescent protein tags get more attention,particularly the green fluorescent protein and red fluorescent protein,which has been used in many research applications.This article will make a briefly review on it.

In vivo fluorescence image analysis system in assessing efficacies of pVAX1-Ag85A and pVAX1-Ag85B DNA vaccines in treatment of bladder cancer cell-implanted tumors in mice / 中国肿瘤生物治疗杂志

Objective: To use in vivo fluorescence image analysis system for evaluating the efficacies of pVAX1-Ag85A and pVAX1-Ag85B DNA vaccines in treatment of bladder cancer cell-implanted tumors in mice. Methods: Discosomasp red fluorescent protein (DsRed) stably transfected bladder cancer BTT cell line (BTT-DsRed) was established and BTT-DsRed cell-implanted mouse model was constructed. Six days later, 24 BTT-DsRed-bearing mice were randomly divided into pVAX1-Ag85A DNA vaccine group, pVAX1-Ag85B DNA vaccine group, and saline group through injecting the pVAX1-Ag85A, pVAX1-Ag85B, and saline into the right hind limbs of mice, respectively. The growth and metastasis of implanted BTT-DsRed tumors were examined by in vivo fluorescence image analysis system. Results: BTT cell line stably transfected with DsRed (BTT-DsRed) was successfully established. Fluorescence visible mouse model was successfully es-tablished by inoculating BTT-DsRed cells into hind limbs of mice. After treatment with pVAX1-Ag85A or pVAX1-Ag85B for 2 weeks, the in vivo tumor fluorescence intensity in pVAX1-Ag85B group was significantly lower than that in the saline group (P <0.05). After 3 weeks, tumor fluorescence intensities in both pVAX1-Ag85A and pVAX1-Ag85B groups were significantly lower than that in the saline group (P < 0.01). But the efficacies of pVAX1-Ag85A and pVAX1-Ag85B groups were similar (P > 0.05). The distant lymphatic metastasis rate in pVAX1-Ag85B group was significantly lower than those in the saline (25.0% vs 87.5%) and pVAX1-Ag85A groups (25.0% vs 62.5%) (P <0.05). Conclusion: In vivo fluorescence image analysis system can dynamically, sensitively and visually evaluate the anti-tumor effects of DNA vaccines against bladder cancer cell-implanted tumors. Both pVAX1-Ag85A and pVAX1-Ag85B DNA vaccines have anti-tumor effects for bladder cancers.

Optical Spectra Diversity and in vitro Molecular Evolution of Red Fluorescent Proteins / 生物化学与生物物理进展

Red fluorescent proteins (RFPs) produced from a number of Anthozoa species have been subjected to a series of in vitro molecular evolution, resulting in various emission spectra ranging from 570 nm to 655 nm and thus providing powerful tools for cellular imaging or even body imaging. This article briefly reviewed the optical properties, structures and mutagenesis of RFPs and their applications.

Transfer pDsRed1-N1 into primary rabbit bone marrow stromal cells by nucleofection / 解放军医学杂志

Objective To approach the feasibility of transfecting the DNA plasmid of encoding red fluorescent protein directly into the nucleus of rabbit primary bone marrow stromal cell with recently developed nucleofection technique. Methods Rabbit primary bone marrow stromal cells (BMSCs) were harvested by means of density gradient centrifugation following a thighbone puncture. The primary BMSCs were cultured and either transfected to pDsRed1-N1 by nucleofectorTM technique (as DsRed group) or left uninfected(as control group) in vitro. The cellular viability, adhesive rate, the growth curves and the efficiency of transfection of both DsRed and control groups were analyzed. Result DsRed were successfully expressed at 48h after nucleofection. Similar morphology evolvement, adhesive rates and growth curves were obtained from the two groups. The positive DsRed expression enhanced gradually alone with a prolonged culturing time, and reached its peak value at the 10th day after marked, with about 54.2% of DsRed-positive cells in the total BMSCs. The DsRed did not attenuate even until 1 month following the mark. Conclusion Neuclofection of pDsRed1-N1 showed no significant effect on the proliferation of rabbit BMSCs. DsRed worked efficiently for the purpose of stable gene marking of rabbit BMSCs, and nucleofection is an efficient method for transferring genes into primary rabbit BMSCs.

Construction of red fluorescent protein reporter gene vector containing HMGB1 promotor and its activity under mechanical stretch / 第三军医大学学报

Objective To construct the red fluorescent protein reporter gene vector containing high mobility group box 1 protein(HMGB1) promoter sequence and study the regulation mechanism of the expression of HMGB1gene under mechanical stretch.Methods HMGB1 promoter was subcloned into a red fluorescent protein vector,pDsRed1-1.After identified by PCR,enzyme digestion and DNA sequencing,the recombinant vector pDsRed1-1-HMGB1P was then transfected into HEK293 cells.Blank vector or pDsRed-1 was transfected into 293 cells and served as controls.The expression of red fluorescent protein and its reaction to mechanical stretch were observed under a fluorescent microscope.HEK293 cells transfected with pDsRed1-1 vector served as control.Results PCR,double restriction enzyme digestion and DNA sequence analysis showed that the recombinant vector,pDsRed1-1-HMGB1P,was constructed correctly.This vector was lowly expressed in HEK293 cells of resting state.But after stimulated by mechanical stretch,strong red fluorescence was observed.No red fluorescence was observed in the control cells.Conclusion A red fluorescent protein reporter gene vector containing HMGB1 promoter sequence has been constructed successfully and expressed highly in mammalian cells.Since it responds to mechanical stretch effectively,it can thus provide a convenient tool to study the regulation mechanism of the expression of HMGB1 gene by mechanical stress.

Construction and expression of red fluorescent protein vectors containing different regions of human eNOS promoter / 中国病理生理杂志

AIM: To construct the plasmid vectors containing different regions of human eNOS promoter coupled to a red fluorescent protein reporter gene, which may express in mammalian cells. METHODS: Different regions of human eNOS promoter were subcloned respectively into a red fluorescent protein vector, pDsRed1-1. These recombinant vectors, pDsF1033Red, pDsF494Red and pDsF166Red, were then transfected into NIH3T3 cell lines, followed by the observation under a fluorescent microscope. RESULTS: After identified to be right by double restriction enzyme digestion, PCR and sequencing, the vectors might be effectively expressed in NIH3T3 cells. 95 % of the red fluorescent emitted by a red fluorescent protein dispersed all over the cells, appearing at 48-60 h after transfection, reaching peak at 96-144 h, becoming the strongest in light at 144 h, gradually disappearing after 168 h and remaining little red fluorescent in 21 days. The quantity and intensity in expressions of red fluorescent protein drived by different regions of human eNOS promoter were clearly lower than by a strong promoter, p CMVIE . CONCLUSION: The red fluorescent protein reporter gene vectors containing different regions of human eNOS promoter are successfully constructed and may efficaciously express in mammalian cells, appearing not strong transcriptional activities, which provide practical and feasible tools to study functions of different regions of human eNOS promoter and roles of cis-elements in it. [

Membrane translocation and location in cells of red fluorescent protein fusion vector incorporated HIV-TAT protein / 解放军医学杂志

Objective To construct the vector that expresses the fusion protein of HIV-Tat protein and red fluorescent protein(mCherry) in mammalian cells,and observe by fluorescence microscopy the intracellular transduction and localization of recombinant protein in cells,in order to obtain a useful tool for the study of the uptake mechanism and intracellular localization of HIV-TAT.Methods With the designed primer coding mCherry sequence,the mCherry gene was amplified by PCR with the vector pmCherry-C2 as template,and inserted into vector pET14b-His-TAT to construct the expression vector pET14b-His-TAT-mCherry.The constructed vector was then transformed into E.coli BL21(DE3),which had been identified by PCR and double digested with restriction endonuclease,followed by sequencing.After IPTG induction,the recombinant protein of His-TAT-mCherry was lyzed and analyzed with SDS-PAGE.Purified His-TAT-mCherry recombinant protein was added to Hela cells and the fluorescence was observed to evaluate the transduction efficiency.Results The results of identification by PCR,digestion with restriction endonuclease and sequencing indicated that the vector His-TAT-mCherry was correctly constructed.His-TAT-mCherry fusion protein was expressed in mammalian Hela cell line and purified successfully,and the fusion protein showed cellular transduction activity.It was found by fluorescence microscopy that the red fluorescence protein located mainly over the cytoplasm,and also the membrane to some extent.Conclusion The expression vector is successfully constructed for HIV-TAT labeled with mCherry sequence.Effective expression and purification of this fusion protein is achieved.It has been observed that the constructed vector may be expressed in mammalian Hela cell under active condition.Thus,it might be useful in the study of uptake mechanism and intracellular localization of HIV-TAT.