Bethesda, Md. (Sept. 22, 2011) -- Maintaining fluid balance in the body is essential to survival, from the tiniest protozoa to the mightiest of mammals. By researching recent genomic data, Swiss researchers have found genetic evidence that links this intricate process to a turning point in evolution.
The study was led by Bernard Rossier, Professor Emeritus, University of Lausanne, along with colleagues Romain A. Studer, Emilie Person, and Marc Robinson-Rechavi. Dr. Rossier will discuss the team's findings at the 7th International Symposium on Aldosterone and the ENaC/Degenerin Family of Ion Channels, sponsored by the American Physiological Society. Dr. Rossier's presentation, "Evolution of ENaC and Na-K-ATPase as Limiting Factors of Aldosterone Action," is based in part on the team's recent article published in the journal Physiological Genomics.
Timing Is Everything
In humans, the hormone aldosterone affects fluid balance by controlling the epithelial sodium channel (ENaC), a protein that traverses a cell's membrane and facilitates the movement of salt into and out of the cell. By searching for genes that descended from a common ancestral DNA sequence (homologs), the researchers found that the emergence of ENaC and Na, K-ATPase (sodium pump), an enzyme that also plays a role in sodium transport, coincided with the emergence of multi-celled organisms.
Dr. Rossier and his team focused their analysis on eukaryotesorganisms whose cells contain complex structures within enclosed membranesand sought to determine when and where on the eukaryotic family tree ENaC first appeared. When tracing the alpha, beta, and gamma subunits of ENaC back, the team found that the beta subunit appeared slightly before the emergence of Metazoans (multicellular animals with differentiated tissues) roughly 750 million years ago.
"The alpha subunit is an old protein found everywhere, in any kind of organism, but the beta and gamma subu
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American Physiological Society