MBP-FGF2-Immobilized Matrix Maintains Self-Renewal and Myogenic Differentiation Potential of Skeletal Muscle Stem Cells

The robust capacity of skeletal muscle stem cells (SkMSCs, or satellite cells) to regenerate into new muscles in vivo has offered promising therapeutic options for the treatment of degenerative muscle diseases. However, the practical use of SkMSCs to treat muscle diseases is limited, owing to their inability to expand in vitro under defined cultivation conditions without loss of engraftment efficiency. To develop an optimal cultivation condition for SkMSCs, we investigated the behavior of SkMSCs on synthetic maltose-binding protein (MBP)-fibroblast growth factor 2 (FGF2)-immobilized matrix in vitro. We found that the chemically well-defined, xeno-free MBP-FGF2-immobilized matrix effectively supports SkMSC growth without reducing their differentiation potential in vitro. Our data highlights the possible application of the MBP-FGF2 matrix for SkMSC expansion in vitro.

Recombinant expression of hepatoma associated gene and its protein function / 中南大学学报(医学版)

OBJECTIVE@#To recombinant express hepatoma associated gene(HTA) and pre-test the function of HTA to determine the role of HTA in the development of liver cancer.@*METHODS@#HTA338-616 was amplified from HepG2 cells and cloned into the prokaryotic expression vector pET21a(+)-MBP. The proteins MBP and MBP-HTA were induced, purified by His-tag magnetic bead purification kit and identified by Western blot and ELISA. HepG2 cells were stimulated with MBP or MBP-HTA proteins. MTT assay and colony formation assay were employed to examine the proliferation of these cells and the changes of cell cycle distribution were determined by flow cytometry.@*RESULTS@#The prokaryotic expression plasmid pET21a(+)-MBP-HTA was successfully constructed. We got a 52 kD purified purpose protein.The proliferation of HepG2 cells stimulated with MBP-HTA was significantly higher than those stimulated with MBP and negative controls. HepG2 cells stimulated with MBP-HTA showed significant decrease fraction in G1 phase and increase fraction in S phase, and the cell proliferation was enhanced.@*CONCLUSION@#HTA protein can significantly promote the proliferation of HepG2 cells, which may be related to the promotion of G1 phase to S phase.

Expression, purification and characterization of non-specific Serratia nuclease in Escherichia coli / 生物工程学报

To efficiently produce non-specific nuclease (NU) of Serratia marcescens through recombinant overexpression approach and to characterize the purified NU. The nuclease gene was amplified from the genomic DNA of Serratia marcescens by PCR and fused into vector pMAL-c4X with maltose binding protein (MBP) tag. The recombinant vector verified by DNA sequencing was transformed into Escherichia coli BL21. The expressed MBP-NU was purified through the amylose resin and its catalytic characters were analyzed. The results showed the NU gene had 97% identities with the reported S. marcescens nuclease gene and intracellularly expressed in E. coli BL21. The optimal expression conditions were 37 degrees C, 0.75 mmol/L IPTG with 1.5 h induction. The purified MBP-NU exhibited non-specific nuclease activity, able to degrade various nucleic acids, including RNA, single-stranded DNA and double-stranded DNA that was circular or linear. Its optimal temperature was 37 degrees C and optimal pH 8.0. From 1 L culture broth 10.8 mg NU could be purified with a specific activity of 1.11x10(6) U/mg. The catalytic activity of NU was not inhibited by reagents such as EDTA (0.5 mmol/L), PMSF (1 mmol/L) and KCl (150 mmol/L) commonly used in protein purification.

Expression, purification and identification of Abeta fusion protein with enhanced solubility / 南方医科大学学报

<p><b>OBJECTIVE</b>To economically obtain the Abeta peptide for Alzheimer's disease (AD) research by expressing the Abeta peptide fused with the maltose binding protein (MBP) possessing high solubility in E.coli.</p><p><b>METHODS</b>The cDNA-coding sequence of Abeta peptide was modified by the addition of a BamH I site at the 5' end and a Hind III site at the 3' end using PCR. The modified sequence was ligated into the maltose-binding protein (MBP) fusion expression vector pMAL-c2 containing an thrombin cleavage site, which was transformed into competent E.coli DH5alpha cells. After identification of the single clones by PCR and DNA sequencing, the recombinant plasmid was transformed into E.coli TB1 and induced to express MBP-Abeta fusion protein. The expressed fusion protein was purified using amylose resin column and identified by SDS-PAGE and Western blotting.</p><p><b>RESULTS</b>The result of DNA sequencing verified the consistency between the inserted sequence and Abeta (1-42) sequence. SDS-PAGE electrophoresis showed that MBP-Abeta fusion protein was highly expressed in E.coli TB1, and Western blotting demonstrated that the purified fusion protein and the separated Abeta peptide could be recognized by specific anti-Abeta (22-35) antibody.</p><p><b>CONCLUSION</b>MBP-Abeta fusion protein highly expressed in E. coli TB1 cells with enhanced solubility and the separated Abeta peptide with good immunogenicity obtained may lend support to AD research.</p>

Effect of different tags on pulldown assays implemented by LMO2 fusion protein / 生物工程学报

Pulldown assay is an in vitro method for studies of protein-protein interactions, in which tagged proteins are usually expressed as the bait to enrich other proteins that could bind to them. In this technology, the GST tag is broadest used for its modest size and hydrophilic property. In most cases, the GST tag could increase the hydrophility of the fusion protein and help to avoid the formation of inclusion bodies. However, in the other few cases, the target protein may be strongly hydrophobic or have complicated structures that were hard to fold and assemble in correct conformations without champerons, and even the existence of GST tag could not make them soluble. These proteins were always expressed as inclusion bodies and had no functions. LMO2 was a small molecular weight and insoluble protein, in this study, GST system and MBP system were used to express GST-LMO2 and MBP-LMO2 fusion proteins, respectively. We found that GST-LMO2 fusion protein was expressed as inclusion bodies whereas MBP-LMO2 fusion protein was expressed in soluble form. Moreover, the production rate of MBP-LMO2 was also much higher than GST-LMO2. Then MBP-LMO2 fusion proteins and renatured GST-LMO2 fusion proteins were used as bait in pulldown assay to study the interaction between LMO2 and endogenous GATA1 in K562 cells. Western blot analyses showed that both of these proteins could bind to endogenous GATA1 in K562 cells, but recovered GATA1 protein by MBP-LMO2 fusion protein was much more than GST-LMO2 fusion protein. These results suggest that using of MBP system is a helpful attempt in the case of studying small molecular weight, strong hydrophobic proteins.

Fusion expression of D-amino acid oxidase from Trignoposis variabilis with maltose binding protein and Vitreoscilla hemoglobin / 生物工程学报

D-amino acid oxidase (DAAO) is one of important industrial enzymes. To increase the solubility and activity of the TvDAAO from Trignoposis variabilis expressed in recombinant Escherichia coli (E. coli), a maltose binding protein (MBP) and Vitreoscilla hemoglobin (VHb) was introduced to fuse with N-terminal of the TvDAAO, respectively. Fusion protein of MBP-TvDAAO was constitutively expressed in JM105/pMKC-DAAO and inductively expressed in JM105/pMKL-DAAO. With respect to the control strain of BL21 (DE3)/pET-DAAO without MBP fusion, the constitutive fusion expression obtained 28% of soluble protein with 3.7 folds of solubility improvement. As for the inductive fusion expression, corresponding results changed to 17% and 1.8 folds, respectively. However, the DAAO activity significantly decreased in the MBP-fusing expression. Fusion protein of VHb-TvDAAO was constructed and inductively expressed in BL21 (DE3)/pET-VDAAO. Its DAAO activity highly reached 3.24 u/mL in flask culture, about 90% increase in contrast to the control without VHb.

Construction of human PPARalphaLBD fusion protein expression vector and optimization of inducing conditions / 生物医学工程学杂志

Peroxisome proliferator-activated receptoralpha (PPARalpha) is a ligand-activated transcription factor which plays a pivotal role in the regulations of metabolism. A cDNA encoding ligand binding domain (LBD) of PPARalpha was amplified by RT-PCR from human hepatic tissue and the product was inserted into the downstream of the malE gene in the vector pMAL-p2X,which encodes maltose-binding protein (MBP). The recombinant plasmid containing MBP-PPARalpha gene was transformed into E. coli. TB1, and then the growth conditions of the recombinant strain were studied, which remarkably influenced the final yield of protein expression. With the use of SDS-PAGE and Bio-Rad Quantity One gel image analysis, we found the best expression condition as follows: The induction was started as OD600 reached 0.5 by the adding of IPTG to a final concentration of 0.4 mmol/L, and then the incubation continued 6 hours at 30 degrees C. The maximum yield of fusion protein was 31.34% of the total mass of cytoplasm proteins. Moreover, the soluble form of the target protein is useful for further work on purification and on screening the ligands of PPARalpha.

Soluble expression of recombinant human BMP6 in Escherichia coli and its purification and bioassay in vitro / 生物工程学报

BMP6 is a potent protein for future treatment strategies of bone regeneration as it is a very important regulator of bone homeostasis. Active BMP6 is a dimer containing multidisulfide bonds and is a highly hydrophobic protein prone to aggregation. To obtain soluble and active BMP6 in Escherichia coli, we compared the effects of four N-terminal fusion tags (TRX, GST, MBP and CBD) and N-terminal His6-tag. The expression and solubility were tested under the different conditions (expression hosts, temperatures and inductor concentrations). A series of experiments leads to the finding that the placement of MBP before the BMP6 is best in availing the soluble expression of the protein. Our study alsodemonstrates that in E. coli BL21trxB(DE3) cytoplasm, which is a thioredoxin reductase mutant strain, soluble homodimeric BMP6 can be formed. The overexpressed MBP-BMP6 fusion protein is purified by chromatography, and shown to be functionally active.

Identification of interaction partners and function analysis of new splicing product of human LMO2 gene / 中华血液学杂志

<p><b>OBJECTIVE</b>To identify the interaction partners of a new splicing product of LMO2 gene (LMO2-C), and study its function in K562 cells.</p><p><b>METHODS</b>Maltose binding protein (MBP) pull down and mammalian two-hybrid assay (MTHA) were used to identify the interaction partners of LMO2-C in K562 cells. Semiquantitative RT-PCR was used to detect the expression of hematopoietic specific gene glycoprotein (GPA) in K562 cells.</p><p><b>RESULTS</b>MBP-LMO2-C fusion protein was expressed and purified in soluble form successfully. Endogenous GATA1 and LDB1 proteins were confirmed to bind to LMO2-C by MBP pull down analysis. The MTHA also showed that LMO2-C had comparable binding affinities to LDB1 with LMO2-L, and over expression of LMO2-C prevented LMO2-L from binding to LDB1, the inhibition rate being (81.13 +/- 0.68)%. RT-PCR results showed that the expression level of GPA was reduced [(51.00 +/- 1.58)%] in K562 cells while LMO2-C overexpressed.</p><p><b>CONCLUSION</b>LMO2-C can bind endogenous GATA1 and LDB1 protein in K562 cells and down regulates the expression of GPA.</p>

Sequence analysis on sorbitol fermentation related genes in Vibrio cholerae / 中华流行病学杂志

<p><b>OBJECTIVE</b>To Investigate the differences of sorbitol fermentation related genes and optimize molecular analysis method for distinguishing an epidemic with nonepidemic strains of Vibrio cholerae.</p><p><b>METHODS</b>Sequence analysis on four genes of sugar fermentation stimulation protein, periplasmic maltose-binding protein, periplasmic phosphate-binding protein and periplasmic amino acid-binding protein.</p><p><b>RESULTS</b>In this study, the following data was noticed: for O1 serogroup El Tor biotype V. cholerae, twenty-four epidemic and eight nonepidemic strains were chosen; For O139 serogroup V. cholerae, five epidemic and four nonepidemic strains were chosen. With those genes of sugar fermentation stimulation protein, there were three point mutations. The 106th, 150th, 378th oligonucleotide in epidemic strains were A, A and T, comparing to the nonepidemic strains which were G, G and C. When comparing the protein sequences, epidemic strains had a Threonine at 36th amino acid, whereas nonepidemic strains had an Alanine. The results in O139 serogroup were consistent with those in O1 serogroup El Tor biotype strains. Another two point mutations were found in the genes of periplasmic maltose-binding protein. The 999th, 1003rd oligonucleotides in epidemic strains were A and C, while in nonepidemic which were G and T. For the gene of periplasmic amino acid-binding protein, two point mutations were noticed. The 504th and 690th oligonucleotides in epidemic strains were T and C, but were C and T in nonepidemic. However, no amino acid differences were found in periplasmic maltose-binding protein and periplasmic amino acid-binding protein. For periplasmic amino acid-binding protein gene, there was no difference on oligonucleotide between epidemic and nonepidemic strains.</p><p><b>CONCLUSION</b>Results suggested that SNPs in these genes might serve as a useful tool to distinguish the epidemic strains from nonepidemic strains. The 36th amino acid mutation of sugar fermentation stimulation protein in epidemic and nonepidemic strains might change the activity of the protein which might be associated with sorbitol fermentation.</p>

Development of Human Antibody Inhibiting RNase H Activity of Polymerase of Hepatitis B Virus Using Phage Display Technique

BACKGROUND: To develop a novel treatment strategy for hepatitis B virus infection, a major cause of liver chirosis and cancer, we aimed to make human monoclonal antibodies inhibiting RNase H activity of P protein playing in important role in HBV replication. In this regard, phage display technology was employed and demonstrated as an efficient cloning method for human monoclonal antibody. So this study analysed the usability of human monoclonal antibody as protein based gene therapy. METHODS: RNase H of HBV was expressed as fusion protein with maltose binding protein and purified with amylose resin column. Single chain Fv (scFv) phage antibody library was constructed by PCR cloning using total RNAs of PBMC from 50 healthy volunteers. Binders to RNase H were selected with BIAcore 2000 from the constructed library, and purified as soluble antibody fragment. The affinity and sequences of selected antibody fragments were analyzed with BIAcore and ABI automatic sequencer, respectively. And finally RNase H activity inhibiting assay was carried out. RESULTS: Recombinant RNase H expressed in E. coli exhibited an proper enzyme activity. Naive library of 4.46 X 10(9) cfu was screened by BIAcore 2000. Two clones, RN41 and RN56, showed affinity of 4.5 X 10(-7) M and 1.9 X 10(-7) M, respectively. But RNase H inhibiting activity of RN41 was higher than that of RN56. CONCLUSION: We cloned human monoclonal antibodies inhibiting RNase H activity of P protein of HBV. These antibodies can be expected to be a good candidate for protein-based antiviral therapy by preventing a replication of HBV if they can be expressed intracellularly in HBV-infected hepatocytes.

Cloning and Expression of the Gene Encoding the 32-kDa Protein of Rickettsia typhi

The crystalline surface layer protein (SLP) and a 28-32 kDa antigen of Rickettsia typhi were known as strong immunogens. We previously reported a cloning and sequence analysis of the SLP gene of R. typhi (slpT) and showed that the open reading frame of this gene encodes both the SLP and a 32-kDa protein. Our study also showed that a 48-kDa protein reacted strongly with polyclonal antiserum of a patient with murine typhus. In this study, we produced three recombinant proteins (SLP, 32-kDa, and 48-kDa protein) in E. coli as fusion proteins with maltose binding proteins. The reactivity of these proteins with patients' sera was investigated.

Molecular Cloning of the Major Immunogen of Orientia tsutsugamushi Thai Strains and Development Passive Hemagglutination Test

The 56-kilodalton protein genes of Orientia tsutsugamushi TA678, TA686, TA716, TA763 strains were amplified by PCR. The amplified products were sequenced and cloned into pIH821 vector. The recombinant proteins were expressed in Escherichia coli as fusion proteins with maltose binding protein. The recombinant proteins were purified and used for the sensitization of sheep RBCs and the reactivity of the recombinant 56-kDa proteins of Orientia tsutsugamushi TA 678, TA686, TA716 strains were analyzed with 40 sera from scrub typhus patients in Korea, 40 sera from scrub typhus in Thailand, Malaysia and Philippines. The 56-kDa protein coding DNA sequence of Orientia tsutsugamushi TA678, TA686, TA716 show 70 to 88% homology with other known strains and four variable regions are also observed. 39 of 40 sera from scrub typhus patients in Korea showed the strongest reactivity to the recombinant protein of Boryong strain and one sera showed the strongest reactivity to the recombinant protein of Gilliam strain. 14 of 40 sera from patients in Thailand, Malaysia and Philippines showed the strongest reactivity to the recombinant protein of TA686 strain and 12 sera showed the strongest reactivity to the recombinant protein of TA716 strain. No serum from patients in Thailand, Malaysia and Philippines showed the strongest reactivity to the recombinant protein of Boryong strain.

Generation of Monoclonal Antibodies Against Human Papillomavirus Type16 E7 Protein : Usefulness for Various E7 Detection Systems

The gene encoding E7 oncoprotein of human papillomavirus type 16 was cloned and expressed in Escherichia coli, and the monoclonal antibodies (Mabs) against this expressed protein were generated. For the efficient immunization, two kind of recombinant E7 protein in fusion form were produced. One was maltose binding protein (MBP) fusion type (MBP-E7) and the other was T7 phage gene 10 product fusioa type (gene 10-E7). Immunization with these two fusion protein to mice, finally two Mabs (VD6 and IB10) were obtained. VD6 and IB10 showed reactivities with E7 protein in CaSki cell but not in HeLa by Western blot analysis. In addition, the Mab, VD6, reacted with COS-7 cell transfected with E7 gene majorly in cytoplasm by immunofluorescence test. Also VD6 could detect E7 protein in cytoplasm and nucleus of CaSki ceU by immunogold electron microscopy. Based on these results, the Mab VD6 was could be used for various E7 detection system such as Western blot analysis and immunohistochemical methods.