An over-reaction when protein synthesis stalls can lead to neurodevelopmental disorders in mice.
The link between quality control during protein synthesis in cells and neurological disorders has been made clear for the first time by RIKEN researchers. This discovery could help to develop new treatments for such cognitive disorders.
Complex molecular factories inside cells, ribosomes convert genetic code into protein molecules. This protein synthesis proceeds in fits and starts, and sometimes it grinds to a complete halt.
When this happens, an important quality-control process kicks in and degrades the incomplete protein threads that have been made, which would otherwise damage cells. This mop-up operation is known as ribosome-associated quality control (RQC).
Recently, there has been some evidence suggesting that various brain disorders result when RQC goes awry, but no-one knew how this occurs.
“Previous studies had suggested that dysfunction of RQC may lead to neurodegenerative disorders,” says Motomasa Tanaka of the RIKEN Center for Brain Science. “So we are really interested in what happens in neurons, but most studies so far have focused on cultured cell lines or yeast cells rather than neurons.”
An artist’s impression of a ribosome. It converts genetic material into proteins that cells need to function. RIKEN researchers have now found the connection between dysregulation of ribosome-associated quality control and cognitive disorders.
Now, Ryo Endo, Tanaka, and co-workers have discovered that removing a key gene in RQC in mice neurons leads to developmental defects in neurons.
Specifically, the team found that mice lacking an enzyme known as LTN1 had higher levels of two signaling molecules: TTC3 and UFMylation. “The abundance of the protein TTC3 increased more than tenfold,” notes Tanaka. “That was really surprising as it’s an overkill.”