scholarly journals Real Time Visualization of Agonist-mediated Redistribution and Internalization of a Green Fluorescent Protein-tagged Form of the Thyrotropin-releasing Hormone Receptor

1998 ◽  
Vol 273 (37) ◽  
pp. 24000-24008 ◽  
Author(s):  
Tomas Drmota ◽  
Gwyn W. Gould ◽  
Graeme Milligan
2001 ◽  
Vol 59 (2) ◽  
pp. 375-385 ◽  
Author(s):  
D. Alex Groarke ◽  
Tomas Drmota ◽  
Daljit S. Bahia ◽  
Nicholas A. Evans ◽  
Shelagh Wilson ◽  
...  

1999 ◽  
Vol 340 (2) ◽  
pp. 529-538 ◽  
Author(s):  
Tomas DRMOTA ◽  
Jiri NOVOTNY ◽  
Gwyn W. GOULD ◽  
Petr SVOBODA ◽  
Graeme MILLIGAN

The rat thyrotropin-releasing hormone receptor-1 (TRHR-1) was modified by the addition of green fluorescent protein (GFP) and expressed stably in HEK293 cells. Extensive overlap of plasma membrane distribution of autofluorescent TRHR-1-GFP with that of the phosphoinositidase C-linked G-proteins Gqα/G11α, identified by indirect immunofluorescence, was monitored concurrently. Addition of thyrotropin-releasing hormone resulted in rapid separation of TRHR-1-GFP and Gqα/G11α signals as the receptor was internalized. This situation persisted for more than an hour. At longer time periods a fraction of the cellular Gqα/G11α was also internalized, although much of the Gqα/G11α immunoreactivity remained associated with the plasma membrane. Parallel experiments, in which the cellular distribution of TRHR-1-GFP and Gqα/G11α immunoreactivity were monitored in sucrose-gradient fractions following cell disruption, also demonstrated a rapid, agonist-induced movement of TRHR-1-GFP away from the plasma membrane to low-density vesicular fractions. At later time points, a fraction of the cellular Gqα/G11α immunoreactivity was also redistributed to overlapping, but non-identical, low-density-vesicle-containing fractions. Pretreatment of the cells with cytochalasin D or nocodazole prevented agonist-induced redistribution of G-protein but not TRHR-1-GFP, further indicating resolution of the mechanics of these two processes. The combination of a GFP-modified receptor and immunostaining of the G-proteins activated by that receptor allows, for the first time, concurrent analysis of the varying dynamics and bases of internalization and redistribution of two elements of the same signal-transduction cascade.


2006 ◽  
Vol 50 (8) ◽  
pp. 2806-2813 ◽  
Author(s):  
T. Ueno ◽  
Y. Eizuru ◽  
H. Katano ◽  
T. Kurata ◽  
T. Sata ◽  
...  

ABSTRACT Promyelocytic leukemia (PML) bodies are discrete nuclear foci that are intimately associated with many DNA viruses. In human cytomegalovirus (HCMV) infection, the IE1 (for “immediate-early 1”) protein has a marked effect on PML bodies via de-SUMOylation of PML protein. Here, we report a novel real-time monitoring system for HCMV-infected cells using a newly established cell line (SE/15) that stably expresses green fluorescent protein (GFP)-PML protein. In SE/15 cells, HCMV infection causes specific and efficient dispersion of GFP-PML bodies in an IE1-dependent manner, allowing the infected cells to be monitored by fluorescence microscopy without immunostaining. Since a specific change in the detergent solubility of GFP-PML occurs upon infection, the infected cells can be quantified by GFP fluorescence measurement after extraction. With this assay, the inhibitory effects of heparin and neutralizing antibodies were determined in small-scale cultures, indicating its usefulness for screening inhibitory reagents for laboratory virus strains. Furthermore, we established a sensitive imaging assay by counting the number of nuclei containing dispersed GFP-PML, which is applicable for titration of slow-growing clinical isolates. In all strains tested, the virus titers estimated by the GFP-PML imaging assay were well correlated with the plaque-forming cell numbers determined in human embryonic lung cells. Coculture of SE/15 cells and HCMV-infected fibroblasts permitted a rapid and reliable method for estimating the 50% inhibitory concentration values of drugs for clinical isolates in susceptibility testing. Taken together, these results demonstrate the development of a rapid, sensitive, quantitative, and specific detection system for HCMV-infected cells involving a simple procedure that can be used for titration of low-titer clinical isolates.


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