Periplasmic expression of human growth hormone via plasmid vectors containing the lambdaPL promoter: use of HPLC for product quantification

The influence of different factors acting on Escherichia coli periplasmic expression of recombinant human growth hormone (hGH) in shake flask cultures has been investigated. Bacterial vectors containing the phage lambdaP(L) promoter, which is temperature activated, were utilized. Four different signal peptides were compared: DsbA, npr, STII and one derived from the natural hGH signal peptide, this last used as a reference. Other factors such as medium composition, optimized induction and expression conditions, and different bacterial strains were also studied. The determination of hGH, carried out directly in osmotic shock fluids, was based on an isocratic reversed-phase high-performance liquid chromatography method, which allows direct, rapid evaluation of the quality and quantity of hGH being secreted in the bacterial periplasmic space immediately after or even during fermentation. The level of hGH production increased 2.5-fold compared with the reference vector, reaching a level of 3.9 +/- 0.63 micro g/ml/A(600) (n = 6; coefficient of variation = 16.2%). The expression level was affected by the signal peptide and by the induction conditions, being more effective when activation started in the early logarithmic phase which, however, exhibited remarkably different optical density (OD) according to medium composition. Our results thus indicate that 6 h activation at 40-42 degrees C, starting with an OD (A(600)) of approximately 3 in a very rich medium, were conditions capable of providing the maximum secretion level for a vector utilizing the DsbA signal sequence and E.coli W3110 or RB791 as host cells.     

SUMO fusion system facilitates soluble expression and high production of bioactive human fibroblast growth factor 23 (FGF23)

As a key humoral regulator of phosphate homeostasis and its involvement in the pathogenesis of human disease, human fibroblast growth factor 23 (hFGF23) has become a particularly attractive therapeutic target. To prepare soluble and bioactive recombinant human FGF23 to meet the increasing demand in its pharmacological application, small ubiquitin-related modifier (SUMO)-FGF23 fusion gene and FGF23 non-fusion gene were amplified by standard PCR methods and cloned into vector pET-22b and pET-3c, then transformed into Escherichia coli Rosetta (DE3) and BL21 (DE3). The best combination of plasmid and host strain was screened, and only Rosetta (DE3)/pET-SUMO-FGF23 was screened for rhFGF23 protein expressed. The average bacterial yield and the soluble expression level of recombinant hFGF23 of three batches attained 687?±?18?g and 30?±?1.5%, respectively, after treatment with 0.4?mM isopropyl-thio-β-galactopyranoside for 19?h at 16?°C in a 30-L fermentor, after which it was purified by DEAE Sepharose FF and nickel nitrilotriacetic acid affinity chromatography. Once cleaved by the SUMO protease, the recombinant human FGF23 was released from the fusion protein. The purity of rFGF23 was shown by high performance liquid chromatography to be greater than 90% and the yield was 60?±?1.5?mg/L. In vitro data showed that the purified rFGF23 can induce the phosphorylation of mitogen-activated protein kinases in the glioma U251 cell. The results of in vivo animal experiments also showed that rFGF23 could decrease the concentration in the plasma of normal rats fed with a fixed formula diet.     

Periplasmic secretion of human growth hormone by Escherichia coli

The gene coding for human growth hormone (hGH) was fused to the coding sequence for the signal peptide of a secreted Escherichia coli protein. STII heat-stable enterotoxin. This hybrid gene was expressed in E. coli. The signal peptide is properly processed and hGH is secreted in to the periplasmic space. In E. coli, some of the material made is proteolytically clipped or deamidated. The effect of culture conditions on the expression and secretion of hGH was studied and several important parameters were identified, including culture temperature and duration, cultivation pH, K+ levels, plasmid structure, and nutrient supplements. Alteration of culture conditions significantly improves the recovery yield and product quality of human growth hormone.     

High-yield production of authentic human growth hormone using a plant virus-based expression system

We describe here a high-yield transient expression system for the production of human growth hormone (hGH, or somatotropin) in transfected Nicotiana benthamiana leaves. The system is based on a recently described plant virus-based modular expression vector [Gleba, Y., Marillonnet, S. and Klimyuk, V. (2004) Engineering viral expression vectors for plants: the 'full virus' and the 'deconstructed virus' strategies. Curr. Opin. Plant Biol. 7, 182-188; Marillonnet, S., Giritch, A., Gils, M., Kandzia, R., Klimyuk, V. and Gleba, Y. (2004) In planta engineering of viral RNA replicons: efficient assembly by recombination of DNA modules delivered by Agrobacterium. Proc. Natl. Acad. Sci. USA, 101, 6852-6857], and represents a simple and fast alternative to stable transformation. By using various combinations of provector modules, hGH was produced in three compartments of the cell: the apoplast, the chloroplast and the cytosol. We found that targeting to the apoplast provided the highest amount of correctly processed and biologically active hGH, with a yield of up to 10% of total soluble protein or 1 mg per gram of fresh weight leaf biomass. These results indicate that the use of viral vectors for high-yield production of human therapeutic proteins in plants by transient expression provides an attractive alternative to production protocols using standard expression vectors in transgenic or transplastomic plants.     

High-level production of bioactive human beta-defensin-4 in Escherichia coli by soluble fusion expression

Human beta-defensin-4 (hBD4) is a cationic 50-amino acid antimicrobial peptide with three conserved cysteine disulfide bonds. It exhibits a broad antimicrobial spectrum. This study describes the synthesis of hBD4 gene, the heterologous fusion expression of the peptide in Escherichia coli, and the bioactive assay of released hBD4. A PCR-based gene SOEing (splicing by overlap extension) synthesis method was used in the synthesis of the hBD4 gene with optimized codons. By constructing the expression plasmid (pET32-smhBD4), high concentration of soluble hBD4 fusion protein (1.9 g/l) can be obtained in E. coli. Further optimization studies showed that the expression system was very efficient to produce soluble target protein, and the solubility of the target protein could attain more than 99% even when the culture temperature was as high as 37°C. The highest productivity (2.68 g/l) of the hBD4 fusion protein was achieved by cultivating the E. coli (pET32-smhBD4) in MBL medium at 34°C, inducing the culture at the mid-exponential phase with 0.4-mM isopropyl β-d-galactopyranoside (IPTG), and collecting the broth after 6-h expression. The soluble target protein accounted for 64.6% of the total soluble proteins, and the mature hBD4 expression level was stoichiometrically estimated to be 0.689 g/l. This fusion protein was then purified and cleaved to get the mature hBD4 peptide that showed antimicrobial activity against E. coli and Pseudomonas aeruginosa.     

Parathyroid hormone induces hepatic production of bioactive interleukin-6 and its soluble receptor

Interleukin-6 (IL-6) is an important mediator of parathyroid hormone (PTH)-induced bone resorption. Serum levels of IL-6 and its soluble receptor (IL-6sR) are regulated in part by PTH. The PTH/PTH-related protein type 1 receptor is highly expressed in the liver, and in the current study we investigated whether the liver produces IL-6 or IL-6sR in response to PTH. Perfusion of the isolated rat liver with PTH-(1-84) stimulated rapid, dose-dependent production of bioactive IL-6 and the IL-6sR. These effects were observed at near physiological concentrations of the hormone such that 1 pM PTH induced hepatic IL-6 production at a rate of approximately 0.6 ng/min. In vitro, hepatocytes, hepatic endothelial cells, and Kupffer cells, but not hepatic stellate cells, were each found to produce both IL-6 and IL-6sR in response to higher (10 nM) concentrations of PTH. Our data suggest that hepatic-derived IL-6 and IL-6sR contribute to the increase in circulating levels of these cytokines induced by PTH in vivo and raise the possibility that PTH-induced, liver-derived IL-6 may exert endocrine effects on tissues such as bone.     

Periplasmic production of correctly processed human growth hormone in Escherichia coli: natural and bacterial signal sequences are interchangeable

We have studied the synthesis, secretion, and processing of human growth hormone (hGH) in Escherichia coli transformed with plasmids engineered for the expression of hGH as a secreted product. In one plasmid, pPreHGH207-2, the coding sequence of the natural hGH precursor (pre-hGH) is placed under the control of the E. coli trp promoter. In a second plasmid, pAPH-1, a DNA fragment containing the E. coli alkaline phosphatase promoter and signal sequence codons is fused to the mature hGH coding sequence (pho-hGH). Most of the hGH was present in the osmotic shock fluids of E. coli cells containing either plasmid, indicating transport to the periplasmic space. Amino acid sequencing of the N termini of the pre-hGH and pho-hGH gene products revealed that both were processed correctly. Electrophoretic analysis of these polypeptides on reducing and nonreducing sodium dodecyl sulfate (SDS)-polyacrylamide (PA) gels indicates that periplasmic hGH is monomeric and contains the same two disulfide bonds as authentic hGH.     

High level expression of bioactive recombinant human growth hormone in the milk of a cloned transgenic cow

Transgenic farm animals have been proposed as an alternative to current bioreactors for large scale production of biopharmaceuticals. However, the efficiency of both methods in the production of the same protein has not yet been established. Here we report the production of recombinant human growth hormone (hGH) in the milk of a cloned transgenic cow at levels of up to 5 g l(-1). The hormone is identical to that currently produced by expression in E. coli. In addition, the hematological and somatometric parameters of the cloned transgenic cow are within the normal range for the breed and it is fertile and capable of producing normal offspring. These results demonstrate that transgenic cattle can be used as a cost-effective alternative for the production of this hormone.     

Expression system for recombinant human growth hormone production from Bacillus subtilis

We demonstrate for the first time, an expression system mimicking serine alkaline protease synthesis and secretion, producing native form of human growth hormone (hGH) from Bacillus subtilis. A hybrid‐gene of two DNA fragments, i.e., signal (pre‐) DNA sequence of B. licheniformis serine alkaline protease gene (subC) and cDNA encoding hGH, were cloned into pMK4 and expressed under deg‐promoter in B. subtilis. Recombinant‐hGH (rhGH) produced by B. subtilis carrying pMK4::pre(subC)::hGH was secreted. N‐terminal sequence and mass spectrometry analyses of rhGH confirm the mature hGH sequence, and indicate that the signal peptide was properly processed by B. subtilis signal‐peptidase. The highest rhGH concentration was obtained at t = 32 h as C_rhGH = 70 mg L^?1 with a product yield on substrate Y_rhGH/S = 9 g kg^?1, in a glucose based defined medium. Fermentation characteristics and influence of hGH gene on the rhGH production were investigated by comparing B. subtilis carrying pMK4::pre(subC)::hGH with that of carrying merely pMK4. Excreted organic‐acid concentrations were higher by B. subtilis carrying pMK4::pre(subC)::hGH, whereas excreted amino‐acid concentrations were higher by B. subtilis carrying pMK4. The approach developed is expected to be applicable to the design of expression systems for heterologous protein production from Bacillus species. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

转人生长激素鼠胚成纤维细胞的暂态表达方法的初步确立

探讨作为转基因克隆动物核供体的、不具备分泌人生长激素（hGH）功能的转hGH鼠胚胎成纤维细胞（tEF）体外表达人生长激素的简便的暂态表达方法。首先,转染,3d后筛选出G418,与无hGH分泌的人乳腺癌细胞株（MCF-7）在聚乙二醇（PEG）作用下融合,培养1～2d,放射免疫分析方法检测相同数量的MCF-7组、转染MCF-7组、tEF组以及融合细胞共4组培养液中hGH的表达。结果显示tEF组和MCF-7组均无hGH表达;二者的融合细胞组培养液中hGH表达量可高达0.84mIU/L。可见,不表达hGH的tEF与MCF-7融合形成的杂种细胞,可作为暂态表达系统检测转基因细胞的表达。     

Periplasmic production of human pancreatic prokallikrein in Escherichia coli

Summary The human pancreatic prokallikrein gene has been fused to the DNA sequence coding for the signal peptide of the Escherichia coli major outer membrane protein F (OmpF) and expressed under the control of tac promoter in E. coli. By induction with isopropyl--d-thiogalactopyranoside, the cells produced prokallikrein very efficiently. The fused OmpF signal peptide was verified as being processed correctly at the cleavage site of the OmpF signal peptide, and the N-terminal amino acid sequence of the product was found to be identical to that of native human prokallikrein. However, the prokallikrein produced by E. coli formed insoluble aggregates and was always collected in the insoluble fraction. An electron micrograph of prokallikrein-producing cells indicated that the prokallikrein was secreted into the periplasmic space and formed insoluble inclusion bodies there. By treating the insoluble inclusion bodies with oxidized and reduced glutathione in 1 M guanidine-HCl solution, a portion of them could be solubilized in water and showed kallikrein activity of 8 units (approx. 264 g kallikrein) per litre of culture by trypsin activation.     

人生长激素基因的cDNA克隆,原核高效表达及纯化

用ＲＴ－ＰＣＲ方法,从含有全长人生长激素（ＨＧＨ）基因的ＣＨＯ细胞中获得ｈｇｈ的ｃＤＮＡ,将其克隆入ｐＥＴ－１１ｂ载体中,在大肠杆菌中获得高效表达,表达量占菌体蛋白总量的２０％。经色谱纯化后,纯度大于９５％。     

Extracellular production of an intact and biologically active human growth hormone by the Bacillus brevis system

The characteristic features of the Bacillus brevis system are very high productivity of heterologous proteins and very low extracellular protease activity. However, degradation of some heterologous proteins, especially mammalian proteins, can be observed and resulted in a lowering of protein productivity. By using a mutant expressing low levels of proteases and the addition of EDTA to the medium, intact human growth hormone (hGH) was successfully produced with the B. brevis system. Signal peptide modification with higher basicity in the amino terminal region and higher hydrophobicity in the middle region brought about a twelve-fold increase in hGH production. The hGH yield was further elevated to 240 mg L⁻¹ by optimization of culture conditions. Thus, biologically active and mature hGH can be efficiently produced directly in the medium with the B. brevis system. Received 06 March 1997/ Accepted in revised form 03 July 1997     

Periplasmic expression of soluble single chain T cell receptors is rescued by the chaperone FkpA

Background  

Efficient expression systems exist for antibody (Ab) molecules, which allow for characterization of large numbers of individual Ab variants. In contrast, such expression systems have been lacking for soluble T cell receptors (TCRs). Attempts to generate bacterial systems have generally resulted in low yields and material which is prone to aggregation and proteolysis. Here we present an optimized periplasmic bacterial expression system for soluble single chain (sc) TCRs.     

Characterization of soluble and particulate parathyroid hormone receptors using a biotinylated bioactive hormone analog

A bioactive biotin-containing derivative of the synthetic bovine parathyroid hormone analog [Nle8,Nle18,Tyr34]bovine parathyroid hormone-(1-34) (bPTH-(1-34] amide was prepared by reacting the peptide with N-biotinyl-epsilon-aminocaproic acid N-hydroxysuccinimide ester. The derivative was incubated with particulate renal plasma membranes or with detergent [3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) extracts of renal cortical membranes, and two membrane components were identified. Labeling of these components was competitively inhibited by underivatized bPTH-(1-34) or bPTH-(3-34) but not by insulin, adrenocorticotropin, or oxidized rat PTH-(1-34). PTH-binding components that were immobilized on nitrocellulose could be detected by incubating the membrane with biotinyl-bPTH-(1-34). Binding components of apparent molecular mass 68, 70, and 150 kDa were specifically labeled in plasma membranes derived from canine, human, and porcine renal cortex, rat liver, and human fibroblasts. The 68-kDa binding protein was found to be consistently more acidic than the 70-kDa binding protein in human, porcine, and canine renal membranes analyzed by two-dimensional electrophoresis. The 68-70-kDa receptor doublet could be specifically isolated by streptavidin-agarose chromatography of solubilized membrane extracts that had first been incubated with biotinyl-BPTH-(1-34). Biotinyl-bPTH-(1-34) should be useful as a tool for further characterization and purification of the PTH receptor.     

Immunoreactive growth hormone production by human lymphocyte cell lines

1. Two human lymphocyte cell lines, a T-cell line and a B-cell line, were shown to produce and secrete immunoreactive growth hormone (irGH). The irGH molecules secreted by the two cell lines appeared to be de novo synthesized and their molecular size was similar to that of pituitary GH as well as irGH secreted by peripheral blood lymphocytes. 2. Affinity-purified irGH molecules had human growth hormone (hGH)-like mitogenic activity on Nb2 cells. These findings indicate that the irGH molecules produced by H9 and IM9 were similar to hGH in structure. 3. However, the irGH messages could not be amplified by polymerase chain reaction (PCR) primers which had been demonstrated to be able to amplify reverse-transcribed hGH messenger RNA successfully, suggesting that the lymphocyte-derived irGH and pituitary hGH are not exactly identical molecules. 4. We conclude that the H9 and IM9 cells produce a growth hormone-related molecule whose structure is different from that in the anterior pituitary.     

Production of bioactive human beta-defensin 5 and 6 in Escherichia coli by soluble fusion expression

This work reports the first successful recombinant expression and purification of human beta-defensin 5 (HBD5) and human beta-defensin 6 (HBD6) in Escherichia coli. HBD5 and HBD6 are cationic antimicrobial peptides with three conserved cysteine disulfide bonds. Two codon-optimized sequences coding the HBD5 gene (sHBD5) and HBD6 gene (sHBD6), respectively, were synthesized, and each gene fused with thioredoxin A (TrxA) to construct the expression vectors. The plasmids were transformed into E. coli BL21 (DE3) strains and cultured in MBL medium, which gave high volumetric productivity of HBD5 and HBD6 fusion proteins of up to 1.49 g L⁻¹ and 1.57 g L⁻¹, respectively. Soluble HBD5 and HBD6 fusion proteins account for 95.2% and 97.6% of the total fusion proteins, respectively. After cell disruption, the soluble fusion proteins were recovered by affinity chromatography and cleaved by enterokinase. Pure HBD5 and HBD6 were recovered using cationic exchange chromatography. The overall recoveries of HBD5 and HBD6 were 38% and 35%, respectively. Importantly, both HBD5 and HBD6 products showed antimicrobial activity against E. coli but not Staphylococcus aureus. Antimicrobial activity against E. coli of both HBD5 and HBD6 were suppressed by NaCl.