CXCR2 Inverse Agonism Detected by Arrestin Redistribution

2009 ◽  
Vol 14 (9) ◽  
pp. 1076-1091 ◽  
Author(s):  
Simone Kredel ◽  
Michael Wolff ◽  
Jörg Wiedenmann ◽  
Barbara Moepps ◽  
G. Ulrich Nienhaus ◽  
...  

To study CXCR2 modulated arrestin redistribution, the authors employed arrestin as a fusion protein containing either the Aequorea victoria—derived enhanced green fluorescent protein (EGFP) or a recently developed mutant of eqFP611, a red fluorescent protein derived from Entacmaea quadricolor. This mutant, referred to as RFP611, had earlier been found to assume a dimeric quarternary structure. It was therefore employed in this work as a “tandem” (td) construct for pseudo monomeric fusion protein labeling. Both arrestin fusion proteins, containing either td RFP611 (Arr td RFP611) or enhanced green fluorescent protein (EGFP; Arr EGFP), were found to colocalize with internalized fluorescently labeled Gro α a few minutes after Gro α addition. Intriguingly, however, Arr td RFP611 and Arr EGFP displayed distinct cellular distribution patterns in the absence of any CXCR2 activating ligand. Under these conditions, Arr td RFP611 showed a largely homoge neous cytosolic distribution, whereas Arr EGFP segregated, to a large degree, into granular spots. These observations indi cate a higher sensitivity of Arr EGFP to the constitutive activity of CXCR2 and, accordingly, an increased arrestin redistribution to coated pits and endocytic vesicles. In support of this interpretation, the authors found the known CXCR2 antagonist Sch527123 to act as an inverse agonist with respect to Arr EGFP redistribution. The inverse agonistic properties of Sch527123 were confirmed in vitro in a guanine nucleotide binding assay, revealing an IC50 value similar to that observed for Arr EGFP redistribution. Thus, the redistribution assay, when based on Arr EGFP, enables the profiling of antagonistic test compounds with respect to inverse agonism. When based on Arr td RFP611, the assay may be employed to study CXCR2 agonism or neutral antagonism. ( Journal of Biomolecular Screening 2009:1076 1091)

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 632
Author(s):  
Yingyun Cai ◽  
Shuiqing Yu ◽  
Ying Fang ◽  
Laura Bollinger ◽  
Yanhua Li ◽  
...  

Simian hemorrhagic fever virus (SHFV) causes acute, lethal disease in macaques. We developed a single-plasmid cDNA-launch infectious clone of SHFV (rSHFV) and modified the clone to rescue an enhanced green fluorescent protein-expressing rSHFV-eGFP that can be used for rapid and quantitative detection of infection. SHFV has a narrow cell tropism in vitro, with only the grivet MA-104 cell line and a few other grivet cell lines being susceptible to virion entry and permissive to infection. Using rSHFV-eGFP, we demonstrate that one cricetid rodent cell line and three ape cell lines also fully support SHFV replication, whereas 55 human cell lines, 11 bat cell lines, and three rodent cells do not. Interestingly, some human and other mammalian cell lines apparently resistant to SHFV infection are permissive after transfection with the rSHFV-eGFP cDNA-launch plasmid. To further demonstrate the investigative potential of the infectious clone system, we introduced stop codons into eight viral open reading frames (ORFs). This approach suggested that at least one ORF, ORF 2b’, is dispensable for SHFV in vitro replication. Our proof-of-principle experiments indicated that rSHFV-eGFP is a useful tool for illuminating the understudied molecular biology of SHFV.


2006 ◽  
Vol 309 (1-2) ◽  
pp. 130-138 ◽  
Author(s):  
Qi-Lai Huang ◽  
Cheng Chen ◽  
Yun-Zi Chen ◽  
Chen-Guang Gong ◽  
Lin Cao ◽  
...  

2010 ◽  
Vol 22 (1) ◽  
pp. 373
Author(s):  
M. Reichenbach ◽  
F. A. Habermann ◽  
H. D. Reichenbach ◽  
T. Guengoer ◽  
F. Weber ◽  
...  

An alternative approach to classic techniques for the generation of transgenic livestock is the use of viral vectors. Using lentiviral vectors (LV) we previously generated transgenic founder cattle with integrants carrying phosphoglycerate kinase (PGK) promoter-enhanced green fluorescent protein (eGFP) expression cassettes (Hofmann et al. 2004 Biol. Reprod. 71, 405-409). The aim of this work was to investigate the transmission of LV-PGK-eGFP integrants through the female and male germ line of transgenic founder cattle in resulting embryos, fetuses, and offspring. The female founder animal was superovulated and artificially inseminated with a nontransgenic bull. Six of the 16 embryos obtained were transferred to synchronized recipient heifers, resulting in 2 pregnancies and birth of 1 healthy male transgenic calf, expressing eGFP as detected by in vivo imaging and real-time PCR. Cryopreserved semen of the founder bull and matured COC of nontransgenic cows were used for in vitro embryo production as previously described by Hiendleder et al. (2004 Biol. Reprod. 71, 217-223). The rates of cleavage and development to blastocysts in vitro corresponded to 52.3 ± 3.8% and 23.5 ± 4.6%, respectively. In vivo expression of eGFP was observed at blastocyst stage (Day 7 after IVF) and was seen in 93.8% (198/211) of all blastocysts. Twenty-four eGFP-positive embryos were transferred to 9 synchronized recipients. Analysis of 2 embryos flushed on Day 15, 2 fetuses recovered on Day 45, and a healthy male transgenic calf revealed consistent high-level expression of eGFP in all tissues investigated. These observations show for the first time transmission of lentiviral integrants through the germ line of female and male transgenic founder cattle. Although eGFP transgenic cattle have been produced before by nuclear transfer from transfected cells, lentiviral transgenesis has the advantage that only one copy of the provirus is integrated at a particular chromosomal integration site. High-fidelity expression of eGFP in embryos, fetuses, and offspring of founders provides an interesting tool for developmental studies in cattle, including interactions of gametes, embryos, and fetuses with their maternal environment.


2007 ◽  
Vol 196 (s2) ◽  
pp. S313-S322 ◽  
Author(s):  
Hideki Ebihara ◽  
Steven Theriault ◽  
Gabriele Neumann ◽  
Judie B. Alimonti ◽  
Joan B. Geisbert ◽  
...  

2005 ◽  
Vol 86 (12) ◽  
pp. 3201-3208 ◽  
Author(s):  
Long P. Le ◽  
Jing Li ◽  
Vladimir V. Ternovoi ◽  
Gene P. Siegal ◽  
David T. Curiel

Canine adenovirus type 2 (CAV2) has become an attractive vector for gene therapy because of its non-pathogenicity and the lack of pre-existing neutralizing antibodies against this virus in the human population. Additionally, this vector has been proposed as a conditionally replicative adenovirus agent under the control of an osteocalcin promoter for evaluation in a syngeneic, immunocompetent canine model with spontaneous osteosarcoma. In this study, a CAV2 vector labelled with the fluorescent capsid fusion protein IX–enhanced green fluorescent protein (pIX–EGFP) was developed. Expression of the fluorescent fusion-protein label in infected cells with proper nuclear localization, and incorporation into virions, could be detected. The labelled virions could be visualized by fluorescence microscopy; this was applicable to the tracking of CAV2 infection, as well as localizing the distribution of the vector in tissues. Expression of pIX–EGFP could be exploited to detect the replication and spread of CAV2. These results indicate that pIX can serve as a platform for incorporation of heterologous proteins in the context of a canine adenovirus xenotype. It is believed that capsid-labelled CAV2 has utility for vector-development studies and for monitoring CAV2-based oncolytic adenovirus replication.


2004 ◽  
Vol 16 (3) ◽  
pp. 315 ◽  
Author(s):  
P. M. Kragh ◽  
G. Vajta ◽  
T. J. Corydon ◽  
S. Purup ◽  
L. Bolund ◽  
...  

Recently, a zona-free technique for bovine somatic cell nuclear transfer (NT) with no requirement for micromanipulation (i.e. hand-made cloning (HMC)) has been described. The present study demonstrates the application of the HMC technique in the production of transgenic porcine blastocysts. In vitro-matured zona-free porcine oocytes were bisected manually using a microblade and halves containing no chromatin (i.e. the cytoplasts) were selected. Two cytoplasts were electrofused with one transgenic fibroblast expressing enhanced green fluorescent protein and reconstructed embryos were activated in calcium ionophore (A23187) followed by 6-dimethylaminopurine. Subsequently, embryos were cultured in NCSU-23 medium supplemented with 4 mg mL–1 bovine serum albumin for 7 days. In five replicates, 93.0 ± 7.0% (mean ± s.e.m.) of attempted reconstructed embryos fused and survived activation (31/31, 15/23, 28/28, 37/37 and 28/28). On Day 7 after activation, the respective blastocyst rates (per successfully reconstructed embryos) were 6% (2/31), 7% (1/15), 7% (2/28), 3% (1/37) and 7% (2/28), resulting in an average of 6.0 ± 0.8%. Enhanced green fluorescent protein was expressed in all cells of all eight developing blastocysts. Efforts are now directed towards the production of offspring from such transgenic NT blastocysts.


2000 ◽  
Vol 182 (11) ◽  
pp. 3254-3258 ◽  
Author(s):  
D. K. Stafslien ◽  
P. P. Cleary

ABSTRACT A glutathione-S-transferase (GST)–C5a–green fluorescent protein (GFP) fusion protein was designed for use as a substrate for the streptococcal C5a peptidase (SCPA). The substrate was immobilized on a glutathione-Sepharose affinity matrix and used to measure wild-type SCPA activity in the range of 0.8 to 800 nM. The results of the assay demonstrated that SCPA is highly heat stable and has optimal activity on the synthetic substrate at or above pH 8.0. SCPA activity was unaffected by 0.1 to 10 mM Ca2+, Mg2+, and Mn2+ but was inhibited by the same concentrations of Zn2+. The assay shows high sensitivity to ionic strength; NaCl inhibits SCPA cleavage of GST-C5a-GFP in a dose-dependent manner. Based on previously published computer homology modeling, four substitutions were introduced into the putative active site of SCPA: Asp130-Ala, His193-Ala, Asn295-Ala, and Ser512-Ala. All four mutant proteins had over 1,000-fold less proteolytic activity on C5a in vitro, as determined both by the GFP assay described here and by a polymorphonuclear cell adherence assay. In addition, recombinant SCPA1 and SCPA49, from two distinct lineages of Streptococcus pyogenes (group A streptococci), and recombinant SCPB, fromStreptococcus agalactiae (group B streptococci), were compared in the GFP assay. The three enzymes had similar activities, all cleaving approximately 6 mol of C5a mmol of SCP−1liter−1 min−1.


2011 ◽  
Vol 23 (1) ◽  
pp. 168
Author(s):  
M. I. Hiriart ◽  
R. J. Bevacqua ◽  
R. Fernandez-Martin ◽  
D. F. Salamone

Isolated blastomeres from 2- and 4-cell embryos are able to generate live offspring. However, the development of each cell of an 8-cell embryo is limited. Tetraploid embryos are used for aggregation with other embryos, embryonic stem cells, and iPS cells, and they are selected against during development of the fetal tissues, but persist in extraembryonic membranes. The objective of this work was to generate a new and simple method for cloning 8-cell bovine embryos and also to explore more efficient methods to multiply transgenic embryos by aggregation of each blastomere from a day-3 embryo with putative tetraploid embryos. To this aim, bovine cumulus–oocyte complexes were in vitro matured in standard conditions and subjected to IVF (day 0) according to Bracket and Oliphant (1975). After IVF, a group of presumptive zygotes was injected with ooplasmic vesicles incubated with 50 ng mL–1 of linearized pCX–egfp. Other group was cultured for 25 additional hours (day 1). At that time 2-cell embryos were electrofused twice at 40V for 25 μs at 100-ms intervals to generate putative tetraploid embryos, visualised as a single blastomere 1 h after the fusion pulse (fused embryos, F). Two aggregation groups were included. A synchronic group (S): IVF for the production of both transgenic embryos and fused embryos was done on the same day; and an asynchronic group (AS): IVF for transgenic embryos took place 1 day before IVF for fused embryos production, so embryos from the A group were younger. Controls consisted of the same S and AS groups, but no fusion was included (NF). On day 3, the enhanced green fluorescent protein [EGFP(+)] blastomeres were selected. Using the well of well system, 1 or 2 embryos of each fusion group (S or AS and F or NF) were removed of their ZP and aggregated in a microwell with one EGFP(+) blastomere from a 5- to 8-cell stage embryo (day 3). In vitro development of the aggregates and green fluorescent protein expression localization of blastocysts were analysed. Blastocysts were obtained for all groups; however, the 2A-F and 2A-NF groups showed the highest rates (44%, P < 0.05) compared with one embryo aggregation. The highest aggregation rates of the EGFP(+) blastomere were observed for 2A-F (67%) and 2A-NF (44%) groups, too. A very poor integration was noted in the 2S-NF (100%), 2S-F (94%), 1A-NF (89%), and 1S-NF (80%) groups. Localised EGFP distribution was also high in the 2A-F group (42%). In all cases, EGFP expression seemed to localise by the inner cell mass. We demonstrated that it is possible to multiply 8-cell embryos of genetic value and also transgenic embryos, in theory reducing mosaicism rates in future offspring. Moreover, our results give rise to the possibility of using EGFP like a reporter gene that could be used to evaluate aggregation efficiency by a fluorescence microscope.


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