VEGF receptor binding peptide‐linked high mobility box group‐1 box A as a targeting gene carrier for hypoxic endothelial cells

High mobility group box‐1 (HMGB‐1) is a nuclear protein that can bind to and condense plasmid DNA. In this study, we developed a recombinant VEGF receptor binding peptide (VRBP) linked to HMGB‐1 box A (VRBP‐HMGB1A) as a targeting gene carrier to hypoxic endothelial cells. Hypoxic endothelial cells in ischemic tissues of solid tumors are important targets for gene therapy. A recombinant VRBP‐HMGB1A expression vector, pET21a‐VRBP‐HMGB1A was constructed. VRBP‐HMGB1A was over‐expressed in BL21 strain and purified by nickel‐chelate affinity chromatography. Complex formation between VRBP‐HMGB1A and pCMV‐Luc was confirmed by gel retardation assay. pCMV‐Luc was retarded completely at a 2/1 weight ratio (peptide/plasmid). For transfection assays, calf pulmonary artery endothelial (CPAE) cells were incubated under hypoxia for 24 h, prior to transfection to induce the VEGF receptors on the cells. VRBP‐HMGB1A/pCMV‐Luc complexes were transfected to hypoxic CPAE cells. The highest transfection efficiency was at a 30/1 weight ratio (peptide/plasmid). In addition, VRBP‐HMGB1A had higher efficiency than poly‐L ‐lysine (PLL) specifically in hypoxic CPAE cells, However, VRBP‐HMGB1A had lower efficiency than PLL in 293, H9C2, and normoxic CPAE cells. In MTT assay, VRBP‐HMGB1A was less toxic than PLL to cells. In conclusion, VRBP‐HMGB1A is a potential gene carrier for targeting hypoxic endothelial cells and thus, may be useful for cancer gene therapy. J. Cell. Biochem. 110: 1094–1100, 2010. Published 2010 Wiley‐Liss, Inc.     

Expression, purification and characterization of TAT-high mobility group box-1A peptide as a carrier of nucleic acids

High mobility group box 1 (HMGB1) is an abundant nuclear protein that binds to double-stranded DNA. HMGB1 is composed of high mobility (HMG) box A, box B, and C-terminal acidic regions. In this study, a recombinant TAT linked HMGB1 box A (rTAT-HMGB1A) peptide was expressed, purified, and characterized as a carrier of nucleic acids. The HMGB1A cDNA was amplified by PCR, and cloned into the pET21a expression vector with the TAT domain located at the N-terminus. The rTAT-HMGB1A peptide was overexpressed and purified using Nickel affinity chromatography. A recombinant HMGB1A (rHMGB1A) peptide without the TAT domain was also overexpressed and purified as a control. In gel retardation assays, both the rHMGB1A and rTAT-HMGB1A peptides formed complexes with DNA equally well. However, transfection assays showed that the rTAT-HMGB1A peptide had a higher gene transfer efficiency than rHMGB1A. Finally, rTAT-HMGB1A had no cytotoxicity to HEK 293 cells suggesting that rTAT-HMGB1A may be useful as a non-toxic gene delivery carrier.     

Characterization of hydrophobic anti-cancer drug-loaded amphiphilic peptides as a gene carrier

An amphiphilic peptide with a 3-arginine stretch and a 6-valine stretch was evaluated as a gene carrier. The short amphiphilic peptide, R3V6, not only formed micelles in aqueous solution, but was also able to deliver plasmid DNA (pDNA) into cells without toxicity. In this research, various amphiphilic peptides were synthesized with a 3-arginine stretch and a 6-valine, -alanine, -leucine, or -phenylalanine stretch. In vitro transfection assays in human embryonic kidney 293 cells showed that R3V6 and R3L6 peptides had higher transfection efficiencies than R3A6, R3F6, and poly-L-lysine (PLL). Since the peptide micelles had hydrophobic cores, a hydrophobic anti-cancer drug, bis-chloronitrosourea (BCNU),was able to be loaded into the cores of the micelles. The incorporation of the hydrophobic drug into the cores of the peptide micelles may stabilize the micelle structure and increase the transfection efficiency. The in vitro transfection assay with BCNU-loaded R3V6 (R3V6-BCNU) or R3L6 (R3L6-BCNU) showed that the BCNU-loaded peptide micelles had a higher transfection efficiency than the peptide micelles without BCNU. R3V6-BCNU and R3L6-BCNU had the highest transfection at a 0.8:1 weight ratio (BCNU:R3V6) and a 1.2:1 weight ratio (BCNU:R3L6), respectively. Furthermore, compared to simple diffusion, a more efficient delivery of the drug into cells may be facilitated by endocytosis of the micelles. R3L6-BCNU and R3V6-BCNU had higher cell toxicity to cells than BCNU alone. Therefore, the R3V6- and R3L6-BCNU may be useful for drug and gene combination cancer therapy.     

Amphiphilic peptides with arginines and valines for the delivery of plasmid DNA

A non-toxic and efficient gene carrier is one requirement for clinical gene therapy. In this study, amphiphilic peptides composed of arginines and valines were synthesized and characterized as plasmid DNA (pDNA) carriers. The peptides have a cationic region containing 1-4 arginines and a hydrophobic region containing 6 valines. The arginine-valine peptides (RV peptides) formed micelles in aqueous solution with a critical micelle concentration (CMC) of 1.35 mg/ml. In gel retardation assay, the RV peptides retarded all pDNA at weight ratios (pDNA:RV peptide) of 1:3 for R1V6, 1:2 for R2V6 and R3V6, and 1:1 for R4V6. A heparin competition assay showed that the R3V6 peptide formed tighter complexes with pDNA than poly-L-lysine (PLL). In vitro transfection assay into HEK293 cells showed that the R1V6 and R2V6 peptides had the highest transfection efficiencies at 1:30 weight ratios (pDNA:RV peptide), while the R3V6 and R4V6 peptides had the highest efficiencies at 1:20 weight ratios. Under optimal conditions, the R3V6 peptide had the highest transfection efficiency of all the RV peptides and PLL. MTT assay showed that the RV peptides did not have any detectable toxicity to cells. Therefore, the RV peptide may be useful for the development of non-toxic gene carriers.     

DNA transfer into human lung cells is improved with Tat-RGD peptide by caveoli-mediated endocytosis

Cell lines and primary cells exhibit varying degrees of resistance to DNA transfection strategies. In this study, we employed the synthetic peptide Tat-RGD (TR), composed of the HIV-1 derived translocation peptide Tat fused to the integrin binding RGD motif, as a tool for improving DNA transfer into pulmonary cells. Binding experiments between DNA and TR and cytotoxicity measurements of TR treated cells were undertaken to optimize DNA and TR concentrations for transfection. Addition of a complex of TR and DNA (TRD) to A549 cells yielded significant transgene expression. When TRD was combined with Lipofectamine (TRDL), the expression was increased by 5-fold over Lipofectamine (DL) and by approximately 30-fold over TRD-mediated transfections. Also, in primary smooth muscle cells (SMC) and fibroblasts (FB) derived from pulmonary arteries, an increase in TRDL-mediated transfection efficiency was observed by a factor of approximately 2 and approximately 3 over that of DL. Laser scanning confocal microscopy for visualizing TR-dependent DNA uptake demonstrated that the internalization of TRDL complexes is linked to caveoli in the plasma membrane. Interfering with caveoli formation by methyl-b-cyclo-dextrin drastically decreased the transfection efficiency by TR. In conclusion, the Tat-RGD peptide mediates efficient gene delivery in human pulmonary cells, in particular when combined with a standard cationic lipid based transfection reagent. The enhancement of DNA uptake by Tat-RGD is suggested to be mediated by caveoli-dependent endocytosis.     

Enhancement of gene delivery using novel homodimeric tat peptide formed by disulfide bond

Cationic liposomes have been actively used as gene delivery vehicle because of their minimal toxicity, but their relatively low efficiency of gene delivery is the major disadvantage of these vectors. Recently, cysteine residue incorporation to HIV-1 Tat peptide increased liposomemediated transfection compared with unmodified Tat peptide. Therefore, we designed a novel modified Tat peptide having a homodimeric (Tat-CTHD, Tat-NTHD) and closed structure (cyclic Tat) simply by using the disulfide bond between cysteines to develop a more efficient and safe nonviral gene delivery system. The mixing of Tat-CTHD and Tat-NTHD with DNA before mixing with lipofectamine increased the transfection efficiency compared with unmodified Tat peptide and lipofectamine only in MCF-7 breast cancer cells and rat vascular smooth muscle cells. However, cyclic Tat did not show any improvement in the transfection efficiency. In the gel retardation assay, Tat-CTHD and Tat-NTHD showed more strong binding with DNA than unmodified Tat and cyclic Tat peptide. This enhancement was only shown when Tat-CTHD and Tat-NTHD were mixed with DNA before mixing with lipofectamine. The effects of Tat- CTHD and Tat-NTHD were also valid in the experiment using DOTAP and DMRIE instead of lipofectamine. We could not find any significant cytotoxicity in the working concentration and more usage of these peptides. In conclusion, we have designed a novel transfection-enhancing peptide by easy homodimerization of Tat peptide, and the simple mix of these novel peptides with DNA increased the gene transfer of cationic lipids more efficiently with no additional cytotoxicity.     

人高迁移率族蛋白B1，高迁移率族蛋白B1Abox和Bbox的原核表达、纯化及高迁移率族蛋白B1多克隆抗血清的制备

目的：获取重组人高迁移率族蛋白B1（HMGB1）,HMGB1Abox和Bbox的纯化蛋白,制备HMGB1的多克隆抗血清。方法：采用PCR方法扩增人HMGB1,HMGB1的Abox和Bbox目的基因片段,构建原核表达载体,进行原核表达与蛋白纯化,然后用HMGB1免疫新西兰大白兔,制备多克隆抗血清。采用ELISA检测抗血清效价,用免疫组化检测HMGB1在小鼠肝损伤组织中的表达。结果：成功构建了人HMGB1,HMGB1的Abox和Bbox原核表达载体pET28-HMGB1、pET28一Abox、pET28-Bbox,在E．co1iBL21中表达,镍亲和层析柱提纯,获取纯净目的蛋白。HMGB1免疫新西兰大白兔后,抗血清效价为1：2,000,000,具有高度特异性。免疫组化显示小鼠坏死肝组织HMGB1表达增加。结论：本研究获得了人HMGB1以及HMGB1的Abox和Bbox的纯化蛋白,制备了人HMGB1的多克隆抗血清,为HMGB1的结构、组织表达谱及其功能的研究奠定了基础。     

Characterization of PLL-g-PEG-DNA nanoparticles for the delivery of therapeutic DNA

Local and controlled DNA release is a critical issue in current gene therapy. As viral gene delivery systems are associated with severe security problems, nonviral gene delivery vehicles were developed. Here, DNA-nanoparticles using grafted copolymers of PLL and PEG to increase their biocompatibility and stealth properties were systematically studied. Ten different PLL-based polymers with no, low, and high PEG grafting and PEG molecular weights as well as different PLL backbone lengths were complexed with plasmids containing 3200 to 10,100 base pairs. Stable complexes were formed and selected for cytotoxicity and transfection efficiency. Predominantly, PLL-g-PEG-DNA nanoparticles grafted with 4 or 5% PEG moieties of 5 kDa transfected 40% COS-7 cells without reduction of cell viability when formed at N/P ratios between 0.1 and 12.5. The molecular weight of PLL did not significantly affect transfection efficiency or cytotoxicity indicating that a specific cationic charge-density-to-PEG-ratio is important for efficient transfection and low cytotoxicity. The PLL-g-PEG-DNA nanoparticles were spherical with a diameter of approximately 100 nm and did not aggregate over 2 weeks. Moreover, they protected included plasmid DNA against serum components and DNase I digestion. Therefore, such storage stable and versatile PLL-g-PEG-DNA nanoparticles might be useful to deliver differently sized therapeutic DNA for in vivo applications.     

The box A domain of high mobility group box-1 protein as an efficient siRNA carrier with anti-inflammatory effects

High mobility group box‐1 (HMGB‐1) is a DNA binding nuclear protein and pro‐inflammatory cytokine. The box A domain of HMGB‐1 (rHMGB‐1A) exerts an anti‐inflammatory effect, inhibiting wild‐type HMGB‐1 (wtHMGB‐1). In this study, HMGB‐1A was evaluated as an siRNA carrier with anti‐inflammatory effects. HMGB‐1A was expressed and purified by consecutive nickel chelate chromatography, cationic exchange chromatography, and polymixin B chromatography. Purified rHMGB‐1A demonstrated an anti‐inflammatory effect, reducing tumor necrosis factor‐α (TNF‐α) in wtHMGB‐1 or lipopolysaccharide (LPS) activated macrophages. In gel retardation assay, rHMGB‐1A formed a stable complex with siRNA at or above a 1:2 weight ratio (siRNA:rHMGB‐1A). A heparin competition assay showed that an siRNA/rHMGB‐1A complex released siRNA more easily than an siRNA/polyethylenimine (PEI, 25 kDa) complex. Luciferase siRNA/rHMGB‐1A reduced firefly luciferase expression at a similar level as luciferase siRNA/PEI complex. Furthermore, TNF‐α siRNA/rHMGB‐1A synergistically reduced TNF‐α expression in LPS activated macrophages. Therefore, rHMGB‐1A may be useful as an siRNA carrier with anti‐inflammatory effects in siRNA therapy for various inflammatory diseases. J. Cell. Biochem. 113: 122–131, 2012. © 2011 Wiley Periodicals, Inc.     

人高迁移率族蛋白B1，高迁移率族蛋白B1 A box和B box的原核表达、 纯化及高迁移率族蛋白B1多克隆抗血清的制备

目的:获取重组人高迁移率族蛋白B1(HMGB1),HMGB1Abox和Bbox的纯化蛋白,制备HMGB1的多克隆抗血清。方法:采用PCR方法扩增人HMGB1,HMGB1的Abox和Bbox目的基因片段,构建原核表达载体,进行原核表达与蛋白纯化,然后用HMGB1免疫新西兰大白兔,制备多克隆抗血清。采用ELISA检测抗血清效价,用免疫组化检测HMGB1在小鼠肝损伤组织中的表达。结果:成功构建了人HMGB1,HMGB1的Abox和Bbox原核表达载体pET28-HMGB1、pET28-Abox、pET28-Bbox,在E.coli BL21中表达,镍亲和层析柱提纯,获取纯净目的蛋白。HMGB1免疫新西兰大白兔后,抗血清效价为1:2,000,000,具有高度特异性。免疫组化显示小鼠坏死肝组织HMGB1表达增加。结论:本研究获得了人HMGB1以及HMGB1的Abox和Bbox的纯化蛋白,制备了人HMGB1的多克隆抗血清,为HMGB1的结构、组织表达谱及其功能的研究奠定了基础。     

High‐mobility group box‐1 induces vascular remodelling processes via c‐Jun activation

Extracellular high‐mobility group box‐1 (HMGB1) acts as a signalling molecule during inflammation, cell differentiation and angiogenesis. Increased abundance of HMGB1 is associated with several pathological disorders such as cancer, asthma and chronic obstructive pulmonary disease (COPD). In this study, we investigated the relevance of HMGB1 in the pathological remodelling present in patients with idiopathic pulmonary arterial hypertension (IPAH) and pulmonary hypertension (PH) associated with COPD. Remodelled vessels present in COPD with PH and IPAH lung samples were often surrounded by HMGB1‐positive cells. Increased HMGB1 serum levels were detected in both patient populations compared to control samples. The effects of physiological HMGB1 concentrations were then examined on cellular responses in vitro. HMGB1 enhanced proliferation of pulmonary arterial smooth muscle cells (PASMC) and primary human arterial endothelial cells (PAEC). HMGB1 stimulated p38, extracellular signal‐regulated kinase (ERK) and c‐Jun N‐terminal kinase (JNK) phosphorylation. Furthermore, activation of the downstream AP‐1 complex proteins c‐Fos and c‐Jun was observed. Silencing of c‐Jun ablated the HMGB1‐induced proliferation in PASMC. Thus, an inflammatory component such as HMGB1 can contribute to PASMC and PAEC proliferation and therefore potentially to vascular remodelling and PH pathogenesis.     

Improved biological activity of antisense oligonucleotides conjugated to a fusogenic peptide.

Recently several groups reported a dramatic improvement of reporter gene transfection efficiency using a fusogenic peptide, derived from the Influenza hemagglutinin envelop protein. This peptide changes conformation at acidic pH and destabilizes the endosomal membranes thus resulting in an increased cytoplasmic gene delivery. We describe the use of a similar fusogenic peptide in order to improve the antiviral potency of antisense oligodeoxynucleotides (anti TAT) and oligophosphorothioates (S-dC28) on de novo HIV infected CEM-SS lymphocytes in serum-free medium. We observed as 5 to 10 fold improvement of the anti HIV activities of the phosphodiester antisense oligonucleotides after chemical coupling to the peptide in a one to one ratio by a disulfide or thioether bond. No toxicities were observed at the effective doses (0.1-1 microM). No sequence specificity was obtained and the fusogenic peptide possessed some antiviral activities on its own (IC50: 6 microM). A S-dC28-peptide disulfide linked conjugate and a streptavidin-peptide-biotinylated S-dC28 adduct showed similar activities as the free S-dC28 oligonucleotide (IC50: 0.1-1 nM). As expected, all the compounds were less potent in the presence of serum but the relative contribution of peptide coupling was maintained.     

Immobilization of HIV-1 TAT peptide on gold nanoparticles: A feasible approach for siRNA delivery

RNA interference is one of the prosperous approaches for cancer treatment. However, small interfering RNA (siRNA) delivery to cancer cells has been faced with various challenges restricting their clinical application over the decades. Since ROR1 is an onco-embryonic gene overexpressed in many malignancies, suppression of ROR1 by siRNA can potentially fight cancer. Herein, a delivery system for ROR1 siRNA based on HIV-1 TAT peptide-capped gold nanoparticles (GNPs) was developed to treat breast cancer. Besides, we introduced a new feasible method for conjugating the peptide to the nanoparticles. Since the GNPs have high affinity to the sulfur, the findings demonstrated the peptide successfully conjugated to the nanoparticles via Au–S bonds. As positively charged nanoparticles showed high cellular uptake, we could use a low concentration of nanoparticles led to high efficient gene transfection with negligible cytotoxicity that was confirmed by flow cytometry, confocal microscopy, gel retardation, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Following transfection, downregulation of ROR1 and its targeted gene, CCND1, induced apoptosis in cancer cells. In conclusion, the reported capped GNPs could be potentially utilized for delivering negatively charged therapeutic agents in particular genes.     

Enhanced nuclear import and transfection efficiency of TAT peptide-based gene delivery systems modified by additional nuclear localization signals

Cellular uptake and nuclear localization are two major barriers in gene delivery. In order to evaluate whether additional nuclear localization signals (NLSs) can improve gene transfection efficiency, we introduced different kinds of NLSs to TAT-based gene delivery systems to form three kinds of complexes, including TAT-PV/DNA, TAT/DNA/PV, and TAT/DNA/HMGB1. The DNA binding ability of different vectors was evaluated by agarose gel electrophoresis. The in vitro transfections mediated by different complexes under different conditions were carried out. The cells treated by different complexes were observed by confocal microscopy. The MTT assay showed that all complexes did not exhibit apparent cytotoxicity in both HeLa and Cos7 cell lines even at high N/P ratios. The luciferase reporter gene expression mediated by TAT-PV/DNA complexes exhibited about 200-fold enhancement as compared with TAT/DNA complexes. Confocal study showed that, except TAT/DNA/PV, all other complexes exhibited enhanced nuclear accumulation and cellular uptake in both HeLa and Cos7 cell lines. These results indicated that the introduction of nuclear localization signals could enhance the transfection efficacy of TAT-based peptides, implying that the TAT peptide-based vectors demonstrated here have promising potential in gene delivery.     

基于人HMGB1-B box的抑制性小肽筛选及其抗炎功能分析

目的从噬菌体构象型7肽库中筛选人HMGB1-Bbox的抑制性小肽。方法以重组人HMGB1-Bbox为靶分子对噬菌体构象型7肽库进行6轮亲和筛选,获得Bbox结合的克隆,并经ELISA验证。选取亲和力高的克隆进行DNA测序,并推导出呈现的多肽序列,通过IL-6 ELISA检测噬菌体呈现的小肽对人HMGB1-B box致炎功能的抑制作用。结果经过6轮亲和筛选,噬菌体的回收率增加,阳性克隆得到富集。挑选15个结合力强的克隆进行测序,推导出2个多肽序列。所获两个阳性噬菌体克隆能特异性地抑制人HMGB1-B box刺激THP-1细胞产生炎症因子的能力。结论获得了噬菌体呈现的能够抑制人HMGB1-B box的两个小肽。     

pET28a-TAT-LacZ重组子的构建

为了构建高表达pET28a-TAT-LacZ重组子,观察表达的融合蛋白TAT-β-Gal能否穿过生物膜,使用人工合成编码TAT蛋白转导区的DNA片段,插入载体pET28a组氨酸编码区后再连接lacZ基因,组成pET28a-TAT-LacZ重组表达子,转化大肠杆菌,利用组氨酸亲和层析柱纯化TAT-β-Gal融合蛋白,将融合蛋白加入培养的平滑肌细胞。得到高度纯化的、有活性的TAT-β-Gal融合蛋白, TAT-β-Gal在短时间内进入体外培养平滑肌细胞,成功地构建了高表达pET28a-TAT-LacZ重组子,并在体外培养的细胞中证实TAT-β-Gal融合蛋白穿透生物膜的能力,为肽类、生物大分子药物进入组织细胞内发挥治疗作用提供了理论基础。     

时钟基因Bmal1促进血管平滑肌细胞增殖

摘要 目的：观察时钟基因Bmal1的过表达对血管平滑肌细胞增殖的影响,进一步探讨生物节律对于血管发育的具体影响。方法：采用包装GV341-Bmal1载体的慢病毒转染的方法构建大鼠胸主动脉平滑肌细胞（A7R5）稳定转染Bmal1的细胞系,实时定量PCR和细胞爬片Bmal1的免疫荧光染色的方法判断所构建细胞系是否稳定过表达Bmal1,细胞爬片Ki67的免疫荧光染色的方法观察时钟基因Bmal1的过表达对血管平滑肌细胞增殖的影响。结果：实时定量PCR结果显示稳定转染Bmal1组细胞Bmal1的表达是对照组的11.2倍（P<0.01）;细胞爬片的免疫荧光染色结果显示稳定转染Bmal1组细胞BMAL1的表达明显升高（P<0.05）,且稳定转染Bmal1组Ki67阳性细胞比例明显升高（P<0.05）。结论：通过慢病毒转染的方法成功构建了血管平滑肌细胞稳定转染Bmal1的细胞系,细胞片Ki67的免疫荧光染色结果显示Bmal1的过表达促进了血管平滑肌细胞的增殖。