August 17, 1994
Media Contact:Joann Rodgers
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"The hardest part of being a complex organism is that a skin cell has to know it's a skin cell, a hair cell has to know it's a hair cell, and all of them have the same genes."
Scientists at The Johns Hopkins Medical Institutions and the University of Michigan have proved that a technique used to study molecular structures is accurate enough to analyze a class of proteins that help control the activity of genes.
The finding is important because scientists could not be certain until now that the information obtained through this technique, extended X-ray absorption fine spectroscopy (EXAFS), was completely accurate.
Information from the study should also help scientists improve EXAFS, making it easier to examine zinc-fingers' role in some forms of cancer, in growth and development processes, and in other important biological phenomena.
For this investigation, Hopkins researchers supplied a number of chemicals known as zinc-binding proteins. The compositions of these chemicals were already well characterized through other methods. Michigan researchers then tried to determine the same information using EXAFS.
"We wanted to see if we could use this technique to find out what we already knew," says Jeremy Berg, Ph. D., director of Hopkins' biophysics department.
They were successful: using EXAFS, they determined much of the same information about the zinc-finger proteins.
First identified in 1985, zinc-finger proteins have since been found in a wide array of biological systems. Scientists believe they play an important role in making genes active or inactive.
"The hardest part of being a [complex] organism is that a skin cell has to know it's a skin cell, and a hair cell has to know it's a hair cell, and all of them have the same genes," explains Berg. "Zinc finger proteins are an important key to how the same genes can do so many different things."
Scientists are just beginning to understand how this process works. For example, Wilm's tumor, a common inherited childhood kidney tumor, has been linked to a mutation in a gene known as WT1, a gene that directs the production of a zinc-finger protein. This protein will normally turn off genes that promote growth of the kidney. When WT1 mutates, though, this growth continues unchecked, producing tumors.
The Hopkins and Michigan researchers will present their findings on EXAFS at the American Chemical Society's August meeting in Washington, D.C. The researchers are currently attempting to use EXAFS to study zinc levels in zebrafish eggs. If they can successfully detect zinc proteins in living tissue, they are hoping to learn more about zinc's role in gene regulation by studying how zinc levels change as the eggs mature into adults.