Human DNA is made up of long chains of three‑letter units called codons. These codons tell the cell how to build proteins, and many of them can be different but still produce the same amino acid. Until now, scientists assumed that those different codons with the same meaning were interchangeable.
However, a research team from Kyoto University and RIKEN, led by scientists Osamu Takeuchi and Takuhiro Ito, has shown that cells don’t treat all codons equally. Some codons are more efficient at producing proteins, while others are weaker. The team discovered that cells actively recognize and silence the less efficient messages, giving stronger instructions priority in gene expression.
Central to this process is a protein called DHX29, which acts like a quality controller. The researchers found that DHX29 attaches to the ribosome the cell’s protein‑making machinery especially when it encounters these weaker codons. Once there, DHX29 recruits another set of proteins, the GIGYF2•4EHP complex, to selectively suppress the weaker genetic messages.
Co‑corresponding author Masanori Yoshinaga explained the importance of the findings:
“Together, these findings reveal a direct molecular link between synonymous codon choice and the control of gene expression in human cells.”
This discovery challenges the long‑held assumption that synonymous codons are functionally the same, revealing a hidden layer of genetic control. It could deepen scientific understanding of critical biological processes such as cell differentiation, balance within cells, and even the development of diseases like cancer.
The researchers say they will continue to explore how DHX29 influences gene activity in both normal physiology and disease.
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