Detection of green fluorescent protein in a single bacterium by capillary electrophoresis with laser-induced fluorescence.

Green fluorescence protein (GFP) is a common reporter used to monitor protein expression in single cells. However, autofluorescence from endogenous components can mask the signal from GFP, particularly at low expression levels in prokaryotes. We employ capillary electrophoresis with laser-induced fluorescence for the analysis of the expression of green fluorescent protein in a single bacterium. Capillary electrophoresis separates GFP from native cellular autofluorescent components, reducing the background signal and improving detection limits. Our system provides 100 ymol (60 copies) limits of detection for GFP. To demonstrate the performance of this instrument, we employ a model system of Deinococcus radiodurans that has been engineered to express GFP under the control of the recA promoter. We report resolution and detection of GFP and autofluorescent components in a single D. radiodurans bacterium. This paper presents the first example of expression of GFP in D. radiodurans and the first detection of GFP in a single bacterium by capillary electrophoresis.

Regulation of fibronectin and metalloproteinase expression by Wnt signaling in rheumatoid arthritis synoviocytes.

OBJECTIVE: The enhanced release of extracellular matrix proteins by fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients is suggestive of joint remodeling. Because Wnt proteins play a critical role in joint development, we investigated whether up-regulated Wnt signaling plays a role in the enhanced synthesis of extracellular matrix proteins. The purpose of the present experiments was to determine the role of Wnt-1-like molecules in the expression of matrix proteins by RA FLS and to ascertain the effects of Wnt antagonists on RA FLS function and survival. METHODS: Transfection with a reporter plasmid (TOPflash) was performed to assess whether Wnt signaling is active in RA FLS. Wnt signaling was up-regulated in normal FLS by transfection with a Wnt-1 expression plasmid and was down-regulated in RA FLS by transfection with dominant-negative lymphoid enhancer factor 1 (LEF-1)/T cell factor 4 (TCF-4) and secreted Frizzled receptor protein 1 (sFRP-1) expression plasmids. Recombinant sFRP-1 and anti-Wnt-1 antibody were also administered to RA FLS to block Wnt signaling. RESULTS: RA FLS had constitutive activation of the canonical Wnt signaling pathway. Transfection of normal FLS with a Wnt-1 expression vector enhanced not only fibronectin, but also pro-matrix metalloproteinase 3 (proMMP-3) expression. In a complementary manner, interference with Wnt signaling using anti-Wnt-1 antibody, the Wnt antagonist sFRP-1, or dominant-negative vectors that inhibited the transcription factors TCF-4/LEF-1 blocked the expression of fibronectin by RA FLS and reduced cell survival. Anti-Wnt-1 antibody and sFRP-1 also blocked the expression of proMMP-3. CONCLUSION: Our results indicate that the canonical Wnt pathway regulates fibronectin and metalloproteinase expression in RA FLS.

Capillary sieving electrophoresis-micellar electrokinetic chromatography fully automated two-dimensional capillary electrophoresis analysis of Deinococcus radiodurans protein homogenate.

We report the one- and two-dimensional (1-D and 2-D) capillary electrophoresis separation of Deinococcus radiodurans protein homogenate. Proteins are labeled with the fluorogenic reagent 3-(2-furoyl)quinoline-2-carboxaldehyde (FQ), which reacts with lysine residues and creates a highly fluorescent product. Detection is by laser-induced fluorescence. 1-D capillary sieving electrophoresis (CSE) produces over 150,000 plates and micellar electrokinetic capillary chromatography (MEKC) produces over 900,000 plates for components in a D. radiodurans protein homogenate. In a 2-D separation, proteins are first separated by CSE. Fractions are repetitively transferred to a second capillary for further separation based on MEKC. The 2-D separation has a approximately 550 spot capacity. Over 150 components are partially resolved from the homogenate. Resolution is limited in the first dimension by diffusion of proteins during the long separation period and in the second dimension by the combination of a long fraction-transfer time and short separation period.