Construction and evaluation of a pUC-type prokaryotic promoter reporter system based on lacZ gene / 生物工程学报

To construct a prokaryotic promoter report system with wide applicability, a series of pFGH reporter vectors based on lacZ gene and pUC replicon were constructed from plasmid pFLX107 through the replacement of multiple cloning sites and sequence modifications. The plasmid with the lowest background activity was selected as the final report system with the lacZ gene deletion strain MC4100 as the host bacterium, following by testing with inducible promoter araBAD and the constitutive promoter rpsM. The background activity of pFGH06 was significantly lower than that of other plasmids of the same series, and even lower than that of reference plasmid pRCL at 28 °C (P<0.01). Further evaluation tests show that the plasmid pFGH06 could be used to clone and determine the activity of inducible promoter or constitutive promoter, and the complete recognition of the target promoter could be achieved through blue-white selection in the simulation test of promoter screening. Compared with the reported prokaryotic promoter report systems, pFGH06 has the advantages of smaller size, more multiple clone sites, adjustable background activity, high efficiency of promoter screening and recognition, thus with a wide application prospect.

Cathepsin L derived from skeletal muscle cells transfected with bFGF promotes endothelial cell migration

Gene transfer of basic fibroblast growth factor (bFGF) has been shown to induce significant endothelial migration and angiogenesis in ischemic disease models. Here, we investigate what factors are secreted from skeletal muscle cells (SkMCs) transfected with bFGF gene and whether they participate in endothelial cell migration. We constructed replication-defective adenovirus vectors containing the human bFGF gene (Ad/bFGF) or a control LacZ gene (Ad/LacZ) and obtained conditioned media, bFGF-CM and LacZ-CM, from SkMCs infected by Ad/bFGF or Ad/LacZ, respectively. Cell migration significantly increased in HUVECs incubated with bFGF-CM compared to cells incubated with LacZ-CM. Interestingly, HUVEC migration in response to bFGF-CM was only partially blocked by the addition of bFGF-neutralizing antibody, suggesting that bFGF-CM contains other factors that stimulate endothelial cell migration. Several proteins, matrix metalloproteinase-1 (MMP-1), plasminogen activator inhibitor-1 (PAI-1), and cathepsin L, increased in bFGF-CM compared to LacZ-CM; based on 1-dimensional gel electrophoresis and mass spectrometry. Their increased mRNA and protein levels were confirmed by RT-PCR and immunoblot analysis. The recombinant human bFGF protein induced MMP-1, PAI-1, and cathepsin L expression in SkMCs. Endothelial cell migration was reduced in groups treated with bFGF-CM containing neutralizing antibodies against MMP-1 or PAI-1. In particular, HUVECs treated with bFGF-CM containing cell-impermeable cathepsin L inhibitor showed the most significant decrease in cell migration. Cathepsin L protein directly promotes endothelial cell migration through the JNK pathway. These results indicate that cathepsin L released from SkMCs transfected with the bFGF gene can promote endothelial cell migration.

Cardiac expression profiles of the naked DNA vectors encoding vascular endothelial growth factor and basic fibroblast growth factor

We investigated expression profiles and biological effects of the naked DNA vectors in the heart. To this end, naked DNA vector was injected into the apex of the beating rat heart after thorocotomy. When the expression of LacZ reporter was examined by reverse transcription-PCR and histochemical staining for b-galactosidase, LacZ expression was detected only in the heart, suggesting limited dissemination of the injected vector in vivo. Even within the heart, LacZ expression was limited to the injection area (apex). Similar observations were made with other transgenes such as VEGF and basic fibroblast growth factor (bFGF), where 77% and 69% of the total transgene exprssion were detected in the heart segments containing the apex. Although VEGF and bFGF expressions were detected until 2 weeks after DNA injection, the highest levels of VEGF and bFGF were observed on day 5 and day 1, respectively. The optimal doses of the vectors were 10 mg and 25 mg for the VEGF and bFGF vectors, respectively. Interestingly, injection of bFGF vector led to 50% increase in the level of endogenous murine VEGF expression. Consistent with this finding, the number of vessels that stained positive for alpha-smooth muscle actin was increased in the bFGF vector-injected heart. These results suggest that simple injection of naked DNA vector may be sufficient to induce significant angiogenesis in the myocardium and that naked DNA gene therapy may be a feasible approach for the treatment of ischemic heart disease.

Wide host range plasmid probe for the heterologous transmission of escherichia coli lac genes

El operon lac de escherichia coli, es un sistema genético que ha sido útil para elucidar principios básicos de variación y expresión genética y para la construcción de cepas microbianas de proyección industrial. En este contexto, hemos derivado por clonación in vivo, un plasmidio de amplio rango de hospedero (pUCV3), que contiene los genes lac de e. coli, los cuales pueden ser ahora transmitidos con facilidad a todos los microorganismos capaces de incorporar replicones IncPa, grupo de compatibilidad al que pertenece pUCV3. Como ejemplo este plasmidio fue transmitido a bacterias marinas y a cytophaga johsonae, microorganismos en los cuales se apreció la expresión regulada del sistema lac. En consecuencia, pUCV3, puede ser usado como sonda para evaluar en comportamiento del operón lac en variados transfondos genéticos microbianos