Frog Eggs Used as Incubators to Study How Influenza Proteins Damage Human Lung Cells

Researchers used a simple frog eggs system to study how an influenza virus protein interferes with the ability of human lung cell membranes to control the passage of fluids.

Investigators at the University of Alabama (Birmingham, USA) used eggs from the frog Xenopus as natural mixing chambers to examine the interaction between the influenza M2 protein and human lung cell epithelial sodium channels (ENaCs). They found that M2 reduced the amount of functional ENaCs, which would decrease the lung cells' ability to regulate fluid transport. Removing a 10 amino acid segment from the C-terminal end of M2 was sufficient to abolish this activity.

After repeating this study in human airway cells, the investigators then showed that M2 protein increased steady-state concentrations of reactive oxygen intermediates that simulated protein kinase C and decreased ENaCs by enhancing endocytosis and its subsequent destruction by the proteasome. These findings were published in the July 13, 2009, issue of The Journal of the Federation of American Societies for Experimental Biology (FASEB).

"We were able to understand the basic mechanisms by which the flu damages key components of the lungs in a simple system, such as the frog eggs, and then confirm these findings in human lung cells,” said senior author Dr. Sadis Matalon, professor of anesthesiology at the University of Alabama. "Under normal conditions, oxidants play an important role, as they destroy pathogens in cells. But our findings suggest that lowering the number of oxidants, or preventing their increase, would prevent damage to the lungs resulting from the M2 protein.”

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