U. researchers identify 2 key muscle proteins

They found that two previously unrelated proteins, Selenoprotein (SepN) and ryanodine receptors (RyR), are needed for a single biochemical pathway that regulates calcium release, which is important for normal muscle development. If the proteins are not present because of a genetic defect, babies are born with congenital myopathies, or skeletal muscle weakness.

"Our work got to the heart of what these genes were doing," said Michael Jurynec, Ph.D. and postdoctoral fellow in human genetics at the U.

Congenital myopathies, though rare, may delay walking, cause respiratory problems and cause joints to deform, Jurynec said.

Previous research showed mutation of many genes, including SepN and RyR, may have caused myopathies, but the recent discovery simplifies research on myopathies.

The researchers used zebrafish because they have the same proteins for muscle development that humans have, which Jurynec attributes to evolution.

Because the zebrafish has an embryo similar to a human embryo, Jurynec said researchers can watch the fish embryo from fertilization and investigate when protein mutations occur.

He said he and other researchers added normal SepN from a zebrafish to human muscle tissue and found they were able to restore RyR activity in the diseased muscle, which he said may help people with myopathies restore their muscle function.

They also studied a diseased human muscle that lacked SepN, and discovered that the muscle must have SepN in order for the RyR to have normal activity.

The relationship between the two proteins was previously unknown.

Unfortunately, restoring muscle function isn't possible yet.

"We have the tools to do this in a fish," Jurynec said, but human testing is in the future. He said researchers would have to extend the research to mice before human clinical trials could begin

"The next step is a way off," Jurynec said.

Jurynec said future research could find other unknown protein relationships, other mutations and causes of other myopathies, and treatments for the muscle diseases.

E-mail: lwilde@desnews.com

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