Quantitative analysis by flow cytometry of green fluorescent protein-tagged human phenylalanine hydroxylase expressed in Dictyostelium

Pteridines ◽  
2017 ◽  
Vol 28 (3-4) ◽  
pp. 153-156
Author(s):  
Hye-Lim Kim ◽  
Hyun-Chul Ryu ◽  
Young Shik Park

AbstractWe have developed a fluorescence assay system to monitor the protein levels of human phenylalanine hydroxylase (hPAH). Wild-type (WT) and three mutant hPAHs (I65T, L255V, and S349L) were expressed as green fluorescent protein (GFP)-tagged forms in a PAH knockout mutant (pah−) of Dictyostelium discoideum Ax2. The fluorescence-activated cell sorting (FACS) analysis showed that the GFP positive cells were the most frequent in WT but were rare in pah−, demonstrating the successful expression of GFP-tagged hPAHs in Dictyostelium. The fluorescence levels of mutants relative to WT were higher than expected from the protein amounts determined from the non-tagged forms, probably due to the presence of the N-terminal GFP. However, treatment of the cells with cumene hydroperoxide, which is known to accelerate protein degradation, decreased fluorescence levels, suggesting that protein stability changes in individual mutations can be monitored by FACS analysis. For an evaluation study, a putative pharmacological chaperone effect of yeast extract on S349L was examined by Western blot and FACS analysis. Both the protein amount and the fluorescence levels were increased by yeast extract, supporting that the FACS analysis could replace the time- and labor-consuming procedures such as the Western blot and cell culture. The fluorescence-based cell assay system may be valuable for the high-throughput screening of pharmacological chaperones for phenylketonuria mutations.

1999 ◽  
Vol 112 (16) ◽  
pp. 2705-2714
Author(s):  
E.M. Burns ◽  
L. Christopoulou ◽  
P. Corish ◽  
C. Tyler-Smith

We have measured the mitotic loss rates of mammalian chromosomes in cultured cells. The green fluorescent protein (GFP) gene was incorporated into a non-essential chromosome so that cells containing the chromosome fluoresced green, while those lacking it did not. The proportions of fluorescent and non-fluorescent cells were measured by fluorescence activated cell sorter (FACS) analysis. Loss rates ranged from 0.005% to 0.20% per cell division in mouse LA-9 cells, and from 0.02% to 0.40% in human HeLa cells. The rate of loss was elevated by treatment with aneugens, demonstrating that the system rapidly identifies agents which induce chromosome loss in mammalian cells.


2001 ◽  
Vol 6 (6) ◽  
pp. 421-428
Author(s):  
C. Renee Albano ◽  
Canghai Lu ◽  
William E. Bentley ◽  
Govind Rao

Green fluorescent protein fusions were constructed with several oxidative stress promoters from Escherichia coli. These promoters were chosen for their induction by reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, and hydroxyl radicals. When exposed to various free radical insults, the cells fluoresced with great specificity based on the corresponding ROS. In this work, we propose a way in which these constructs could be used to study the mode of action of a variety of antitumor drugs. This approach offers the possibility of complementing gene chip technology by the creation of living chips for high throughput screening as well as studying differential gene expression.


2003 ◽  
Vol 47 (12) ◽  
pp. 3682-3687 ◽  
Author(s):  
Chartchai Changsen ◽  
Scott G. Franzblau ◽  
Prasit Palittapongarnpim

ABSTRACT The green fluorescent protein (GFP) gene offers many advantages as a viability reporter for high-throughput antimicrobial drug screening. However, screening for antituberculosis compounds by using GFP driven by the heat shock promoter, hsp60, has been of limited utility due to the low signal-to-noise ratio. Therefore, an alternative promoter was evaluated for its enhanced fluorescence during microplate-based culture and its response to 18 established antimicrobial agents by using a green fluorescent protein microplate assay (GFPMA). Mycobacterium tuberculosis strains H37Rv, H37Ra, and Erdman were transformed with pFPCA1, which contains a red-shifted gfp gene driven by the acetamidase promoter of M. smegmatis mc2155. The pFPCA1 transformants achieved higher levels of GFP-mediated fluorescence than those carrying the hsp60 construct, with signal-to-noise ratios of 20.6 to 27.8 and 3.8 to 4.5, respectively. The MICs of 18 established antimicrobial agents for all strains carrying pFPCA1 in the GFPMA were within 1 to 2 twofold dilutions of those determined by either the fluorometric or the visual microplate Alamar Blue assay (MABA). No significant differences in MICs were observed between wild-type and pFPCA1 transformants by MABA. The optimized GFPMA is sufficiently simple, robust, and inexpensive (no reagent costs) to be used for routine high-throughput screening for antituberculosis compounds.


2013 ◽  
Vol 27 (5) ◽  
pp. 741-753 ◽  
Author(s):  
Qunsheng Dai ◽  
Anish A. Shah ◽  
Rachana V. Garde ◽  
Bryan A. Yonish ◽  
Li Zhang ◽  
...  

Abstract The cDNA for a novel truncated progesterone receptor (PR-M) was previously cloned from human adipose and aortic cDNA libraries. The predicted protein sequence contains 16 unique N-terminal amino acids, encoded by a sequence in the distal third intron of the progesterone receptor PR gene, followed by the same amino acid sequence encoded by exons 4 through 8 of the nuclear PR. Thus, PR-M lacks the N terminus A/B domains and the C domain for DNA binding, whereas containing the hinge and hormone-binding domains. In this report, we have localized PR-M to mitochondria using immunofluorescent localization of a PR-M-green fluorescent protein (GFP) fusion protein and in Western blot analyses of purified human heart mitochondrial protein. Removal of the putative N-terminal mitochondrial localization signal obviated association of PR-M with mitochondria, whereas addition of the mitochondrial localization signal to green fluorescent protein resulted in mitochondrial localization. Immunoelectron microscopy and Western blot analysis after mitochondrial fractionation identified PR-M in the outer mitochondrial membrane. Antibody specificity was shown by mass spectrometry identification of a PR peptide in a mitochondrial membrane protein isolation. Cell models of overexpression and gene silencing of PR-M demonstrated a progestin-induced increase in mitochondrial membrane potential and an increase in oxygen consumption consistent with an increase in cellular respiration. This is the first example of a truncated steroid receptor, lacking a DNA-binding domain that localizes to the mitochondrion and initiates direct non-nuclear progesterone action. We hypothesize that progesterone may directly affect cellular energy production to meet the increased metabolic demands of pregnancy.


2005 ◽  
Vol 71 (5) ◽  
pp. 2338-2346 ◽  
Author(s):  
Anders Norman ◽  
Lars Hestbjerg Hansen ◽  
Søren J. Sørensen

ABSTRACT Four different green fluorescent protein (GFP)-based whole-cell biosensors were created based on the DNA damage inducible SOS response of Escherichia coli in order to evaluate the sensitivity of individual SOS promoters toward genotoxic substances. Treatment with the known carcinogen N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) revealed that the promoter for the ColD plasmid-borne cda gene had responses 12, 5, and 3 times greater than the recA, sulA, and umuDC promoters, respectively, and also considerably higher sensitivity. Furthermore, we showed that when the SOS-GFP construct was introduced into an E. coli host deficient in the tolC gene, the minimal detection limits toward mitomycin C, MNNG, nalidixic acid, and formaldehyde were lowered to 9.1 nM, 0.16 μM, 1.1 μM, and 141 μM, respectively, which were two to six times lower than those in the wild-type strain. This study thus presents a new SOS-GFP whole-cell biosensor which is not only able to detect minute levels of genotoxins but, due to its use of the green fluorescent protein, also a reporter system which should be applicable in high-throughput screening assays as well as a wide variety of in situ detection studies.


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