Fluorescent Protein From Unagi Eel To Revolutionize Liver Clinical Test

Researchers found a fluorescent protein in Japanese freshwater eel that could to used in a clinical test for liver function.

AsianScientist (Jun. 17, 2013) – Researchers at Japan’s RIKEN Brain Science Institute have found a fluorescent protein in Japanese freshwater eel that could be used in a clinical test for liver function.

Best known as a culinary delicacy from Japan, the freshwater eel unagi (Anguilla japonica) and related species have seen a worldwide decrease in population, and is on the brink of extinction in Japan. Yet almost nothing is known about the biology of the eel.

Drs. Atsushi Miyawaki, Akiko Kumagai, and their team cloned a gene from unagi for an unusual protein that allows eels to glow in the dark. The protein, which they named Unagi Green protein (UnaG), is the first fluorescent protein found in vertebrates; previously they were thought to exist only in simple animals like jellyfish.

But what makes UnaG truly unique in nature is that it needs a natural chemical to activate its powerful green light emission. In a surprise twist, the compound was identified by the authors to be bilirubin, a slippery molecule universally used in clinical labs around the world as a human blood marker for liver function.

Bilirubin is the breakdown product of blood hemoglobin and is toxic if present in excess in the body like in the characteristic yellow skin and eye color conditions seen in newborn babies born with jaundice. It is also a common marker in blood tests to assess liver function and hemolysis, the loss of red blood cells in anemia.

By analyzing the structure of UnaG, the team discovered a novel mechanism of fluorescence enabling bilirubin to bind to UnaG and activate its light emission. Using this property, they developed a new assay for bilirubin with high sensitivity, accuracy, and speed that may someday become the global clinical standard in liver tests.

“We believe that UnaG provides an unexpected foothold into several important but currently obscure areas of human health including bilirubin metabolism and muscle physiology during endurance exercise,” Miyawaki said. “Before the discovery of UnaG, I couldn’t imagine that basic science could have such a direct impact on human health. From a simple eel, we found a new path to the clinic.”

The article can be found at: Kumagai A et al. (2013) A Bilirubin-Inducible Fluorescent Protein from Eel Muscle.


Source: RIKEN.
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