Researchers report that a protein known to be important for protein synthesis also influences muscle regeneration and regeneration in an unexpected way. The finding, reported in the Journal of Clinical Research, may one day lead to new methods for treating disorders that result in muscle weakness and loss of muscle mass, the researchers said.
Scientists have long studied leucine-tRNA synthetases, or LRS, for their role in protein synthesis, said Jie Chen, a professor of developmental biology and cell at the University of Illinois, who led the research.
"Over the past 5-10 years, scientists have begun to realize that LRS and other similar proteins have functions independent of protein synthesis," Chen said. "Previously, my laboratory and other laboratories have found that one of these LRS functions is that it can regulate cell growth." Our new study is the first report of its role in muscle regeneration. "
Chen and his colleagues used cultures of mammalian and mouse cells in the new study. They compared the speed of muscle repair in mice with normal and below-normal LRS levels. They found that mice with lower levels of LRS in their tissues recovered from muscle injuries much faster than their counterparts with normal levels of LRS.
A 70% reduction of LRS proteins in the cell does not affect protein synthesis, Chen said.
"But lower levels positively influence muscle regeneration," she said. "We have seen that, seven days after the injury, the repaired muscle cells are larger when the LRS is smaller."
Although it is not possible to reduce LRS in humans, the researchers looked for another method to block their effects.
Chen and his colleagues further uncovered the exact molecular mechanism by which LRS influences muscle regeneration. This led them to hypothesize that a nontoxic inhibitor that their co-workers in South Korea developed previously would block the effect of LRS on muscle cells without interfering with their role in protein synthesis.
"We have shown that this inhibitor works on both mammalian and mouse cells," Chen said. Muscle repair occurred faster – and regenerated muscles were stronger – when the inhibitor was present.
As science progresses, researchers are gaining a broader view of the multifunctionality of proteins, which were once thought to have only a single role in cells, Chen said.
"We now understand that & quot; clandestine protein & quot; where a protein does many different things in the cell, is the norm," she said.
Chen and his colleagues are investigating the effect of LRS on older rats, which tend to rebuild their muscles more slowly and have less muscle tone than younger rats.