Fluorescent proteins to see cancer molecules

26 Jan 2009, 2203 hrs IST, IANS

WASHINGTON: Novel new tools, developed by researchers, can now spotlight cellular molecules inside a cancer cell, transforming biomedical research.
They are photoactivatable fluorescent proteins (PAFPs) and other fluorescent proteins (FPs), several of which have been developed by Vladislav Verkhusha, associate professor of anatomy & structural biology at Albert Einstein College of Medicine.

It is possible, for example, to follow cancer cells as they seek out blood vessels and spread throughout the body or to watch how cells manage intracellular debris, preventing premature aging.

These new fluorescent proteins add considerably to the biomedical imaging revolution started by the 1992 discovery that the gene for a green fluorescent protein (GFP) found in a jellyfish could be fused to any gene in a living cell.
When the target gene is expressed, GFP lights up (fluoresces), creating a visual marker of gene expression and protein localisation, via light (optical) microscopy. Three scientists won The 2008 Nobel Prize in Chemistry for their GFP-related discoveries.

However, many cellular structures, which could hold the key to managing or curing disease, are a small fraction of that size? Just a few nanometers or more.
Using a sophisticated combination of lasers, computers, and highly sensitive digital cameras, scientists have been able to surmount the barriers of optical imaging.
The first generation of these new imaging devices, collectively known as super-resolution (SR) fluorescence microscopes, were able to capture images as small as 15 to 20 nanometres - the scale of single molecules.

But this could be done only in non-living cells. The addition of PAFPs, more versatile versions of FPs, made it possible to do real-time SR fluorescence microscopy in living cells. Last month, Nature Methods selected SR fluorescence microscopy as the 2008 Method of the Year.

Verkhusha has developed a variety of PAFPs and FPs for use in imaging mammalian cells, expanding the applications of fluorescence microscopy.

Among these are PAFPs that can be turned on and off with a pulse of light, FPs that can fluoresce in different colours, and FPs that have better resolution for deep-tissue imaging, said an Einstein release.

Several studies have employed Verkhusha's PAFPs, revealing new insights into a variety of biological processes.