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NSF Press Release

 


NSF PR 01-14 - February 26, 2001

Media contact:

 Tom Garritano, NSF

 (703) 292-8070

 tgarrita@nsf.gov

Program contact:

 Randoph Addison, NSF

 (703) 292-8442

 raddison@nsf.gov

 

 Wolfgang Dostmann,
 University of Vermont

 (802) 656-0381

 dostmann@salus.med.uvm.edu


This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.

Biologists Create a New Tool for Observing a "Messenger" Molecule in Living Cells
Understanding a key molecule that affects fundamental cell processes

Researchers have developed an important tool for understanding how one key molecule regulates a wide range of physiological activity in mammals. Using the natural tendency of certain proteins to glow - their fluorescence - research funded in part by the National Science Foundation (NSF) has revealed some surprising variations in how even cells of the same type behave.

Cyclic guanosine monophosphate (cGMP) is a messenger molecule that influences muscle tone, nerve sensitivity, sexual response, vision and learning, among other physiological processes. Understanding cGMP behavior could in turn yield techniques for regulating its positive or negative effects in humans.

The NSF-funded portion of the research was conducted by Wolfgang Dostmann at the University of Vermont. He and University of California, San Diego colleague Roger Tsien - who is funded by the National Institutes of Health and the Howard Hughes Medical Institute - drew on methods from molecular biology, protein/peptide chemistry and cell biology to construct a set of fluorescent indicators named "cygnets," for cyclic GMP indicator using energy transfer.

According to Randolph Addison, program officer in NSF's Signal Transduction Program, "Dostmann and Tsien ingeniously created genetically encoded indicators that can help us solve fundamental questions such as how cells perceive and respond to other cells."

Until now, cGMP could only be observed invasively, by killing and homogenizing the tissue. Such techniques can yield unreliable results, compared with examining cells in their natural circumstances. The non-invasive cygnet technique, because it allows study of living tissue, is yielding much more detailed and reliable results.

This crucial molecule has been mystifying because it may appear very briefly and in small concentrations within a cell. To be announced in the February 27, 2001 issue of Proceedings of the National Academy of Sciences, Dostmann's and Tsien's results demonstrate that, even in cells of the same type, cGMP can appear in widely varying concentrations and will react to stimuli in surprising ways. For instance, some cells respond quickly to stimuli by producing cGMP, while others under the same stimulation may yield no perceptible traces of the molecule.

Still other cells exhibit what appears to be microscopic "tides" of cGMP that travel perceptibly from one side of the cell to another. The researchers created the detector cygnets by sandwiching a cGMP-sensitive protein between two colors of a protein that spontaneously becomes fluorescent when placed in mammalian cells. By using cygnets, biologists may be able to explain fundamental cell behaviors that until now were difficult or impossible to observe.

 

Emission of cGMP as traced by cygnets; caption is below
See a video clip:
cygnets.avi     2.5 mb

This video clip shows the emission of cGMP as traced by cygnets. The red pattern represents a "wave" of cGMP passing through the cell.

stages of cygnet; caption is below
In panels A and B, the localization of cygnet in a cultured cell as demonstrated by light emission at 475 nanometers (A) and at 525 nanometers (B). One nanometer (nm) is a billionth of a meter.

In panels C and D, the pseudocolor of the ratio of fluorescence of a cultured cell with cygnet in the absence (C) and in the presence (D) of a stimulus (i.e., cGMP).

A brain cell containing cygent (E) and a brain cell exposed to an antibody against a protein that binds cGMP (F). The two images were then superimposed to reveal in yellow where cygnet and the cGMP-protein were localized.

A larger version is here.

 

-NSF-

For an animation of cGMP, see: http://nsf.gov/od/lpa/news/press/01/pr0114.htm
For the Dostmann/Tsien article in Proceedings of the National Academy of Sciences, see: http://www.pnas.org

 

 
 
     
 

 
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