Biomedical subjects

Wensheng Luo

Publications and source records attributed to Wensheng Luo.

5 recordsLinked to original sources

PubMed2006

Analysis of the function of enteropathogenic Escherichia coli EspB by random mutagenesis.

Enteropathogenic Escherichia coli (EPEC) is an important cause of infantile diarrhea, especially in developing countries. EspB, a key virulence factor of EPEC, is required for the attaching and effacing effect characteristic of EPEC and enterohemorrhagic E. coli and has been posited to play several functions in the process of infection. Attaching and effacing activity is associated with the accumulation of filamentous actin beneath adherent bacteria as measured in the fluorescence actin staining (FAS) test. To determine whether different domains of EspB are responsible for different functions, 42 plasmids carrying mutated espB were introduced into an espB deletion mutant. Two major groups of espB mutants were identified. One group of 17 mutants exhibited positive FAS results and normal levels of hemolytic activity. Another group of 22 mutants exhibited negative FAS results and low levels of hemolytic activity. Three mutants were exceptional. One mutant was FAS positive but had significantly reduced hemolytic activity. Conversely, a second mutant was FAS negative but had full hemolytic activity. A third mutant had a significantly reduced FAS level compared to the wild type but full hemolytic activity. The results of EspF and Tir translocation assays confirmed that FAS-negative insertions disrupt effector translocation and mutants with FAS-positive insertions retain protein translocation activity. These results suggest that EspB has distinct domain functions involved in effector translocation that can be distinguished from its role as a component of the translocation pore.

Actins↗

PubMed2005

A SAGE-based comparison between glomerular and aortic endothelial cells.

Endothelial cells have many characteristics in common, but significant morphological and functional differences exist between endothelial cells from different anatomic sites. The specific glomerular endothelial (GEn) cell transcript repertoire is unknown. We sought to determine whether endothelial cells derived from bovine glomeruli display a distinct transcriptional profile compared with bovine aortic endothelium (BAE) under identical conditions. Serial analysis of gene expression (SAGE), which includes known and unknown transcripts, was used to make the comparison. The GEn and BAE SAGE libraries contain 36,844 and 26,452 total tag sequences, respectively. Among 6,524 unique tag sequences represented at least 2 times in the 2 libraries, 2,094 (32%) were matched to well-characterized bovine cDNA sequences (358 tags) or expressed sequence tags (EST). Identification of the human homolog was achieved for 1,035 of these tags. Forty-two tags were differentially expressed in GEn. For 25 of these, the bovine cDNA or EST, and for 17 the human homolog was identified. Among all transcripts with a known bovine and human tag, seven were expressed at levels more than 10-fold higher in cultured GEn cells compared with all other SAGE libraries. The transcript "DKFZp564B076" was localized by in situ hybridization to glomerular endothelium in vivo and was shown by real-time RT-PCR to be highly abundant in glomeruli compared with aortic intima. This work supports the concept that differences in the transcriptional profile of endothelial cells from distinct origins are observed under otherwise equivalent conditions. Furthermore, we have identified the first known transcript predominant in glomerular endothelium in vivo.

Animals↗

PubMed2005

c-di-GMP (3'-5'-cyclic diguanylic acid) inhibits Staphylococcus aureus cell-cell interactions and biofilm formation.

Staphylococcus aureus is an important pathogen of humans and animals, and antibiotic resistance is a public health concern. Biofilm formation is essential in virulence and pathogenesis, and the ability to resist antibiotic treatment results in difficult-to-treat and persistent infections. As such, novel antimicrobial approaches are of great interest to the scientific, medical, and agriculture communities. We recently proposed that modulating levels of the cyclic dinucleotide signaling molecule, c-di-GMP (cyclic diguanylate [3',5'-cyclic diguanylic acid], cGpGp), has utility in regulating phenotypes of prokaryotes. We report that extracellular c-di-GMP shows activity against human clinical and bovine intramammary mastitis isolates of S. aureus, including methicillin-resistant S. aureus (MRSA) isolates. We show that chemically synthesized c-di-GMP is soluble and stable in water and physiological saline and stable following boiling and exposure to acid and alkali. Treatment of S. aureus with extracellular c-di-GMP inhibited cell-to-cell (intercellular) adhesive interactions in liquid medium and reduced (>50%) biofilm formation in human and bovine isolates compared to untreated controls. c-di-GMP inhibited the adherence of S. aureus to human epithelial HeLa cells. The cyclic nucleotide analogs cyclic GMP and cyclic AMP had a lesser inhibitory effect on biofilms, while 5'-GMP had no major effect. We propose that cyclic dinucleotides such as c-di-GMP, used either alone or in combination with other antimicrobial agents, represent a novel and attractive approach in the development of intervention strategies for the prevention of biofilms and the control and treatment of infection.

Animals↗

PubMed2004

Inhibition of accelerated graft arteriosclerosis by gene transfer of soluble fibroblast growth factor receptor-1 in rat aortic transplants.

OBJECTIVE: Because increased fibroblast growth factor-1 (FGF-1) and FGF receptor (FGFR) expression correlate with the development of accelerated graft arteriosclerosis in transplanted human hearts, this study sought to determine whether local gene transfer of soluble FGFR-1, capable of binding both FGF-1 and FGF-2, could blunt the development of accelerated graft arteriosclerosis in the rat aortic transplant model. METHODS AND RESULTS: A construct encoding the FGFR-1 ectodomain, capable of neutralizing FGF-2 action, was expressed in rat aortic allografts, using adenoviral gene transfer at the time of transplantation. Neointima formation was inhibited in aortic allografts transduced with soluble FGFR-1, compared with allografts transduced with Null virus. CONCLUSIONS: FGFs play a causal role in the development of accelerated graft arteriosclerosis in the rat aortic transplant model. Targeted interruption of FGF function could potentially reduce neointima formation in patients with heart and kidney transplants.

Adenoviridae↗

PubMed2004

SepL, a protein required for enteropathogenic Escherichia coli type III translocation, interacts with secretion component SepD.

Enteropathogenic Escherichia coli (EPEC), an important cause of infantile diarrhoea in the developing world, disrupts host cell microvilli, causes actin rearrangements and attaches intimately to the host cell surface. This characteristic phenotype, referred to as the attaching and effacing (A/E) effect, is encoded on a 36 kb pathogenicity island called the locus of enterocyte effacement (LEE). The LEE includes genes involved in type III secretion and translocation, the eae gene encoding an outer membrane adhesin known as intimin, the tir gene for the translocated intimin receptor, a regulator and various genes of unknown function. Among this last group is sepL. To determine the role of SepL in EPEC pathogenesis, we constructed and tested a non-polar sepL mutant. We found that this sepL mutant is deficient for A/E and that it secretes markedly reduced quantities of those proteins involved in translocation (EspA, EspB and EspD), but normal levels of those proteins presumed to be effectors (Tir, EspF and EspG). Despite normal levels of secretion, the mutant strain was unable to translocate EspF and Tir into host cells and formed no EspA filaments. Fractionation studies revealed that SepL is a soluble cytoplasmic protein. Yeast two-hybrid and affinity purification studies indicated that SepL interacts with the LEE-encoded protein SepD. In contrast to SepL, we found that SepD is required for type III secretion of both translocation and effector proteins. Together, these results demonstrate that SepL has a unique role in type III secretion as a functional component of the translocation system that interacts with an essential element of the secretion machinery.

Bacterial Adhesion↗