A study, published in the journal eLife, reports a recent discovery at the Stowers Institute for Medical Research. It reveals a new function of ribosomes in human cells. According to the study, ribosomes play a role in destroying healthy mRNAs, the messages that decode DNA into protein.
For a long time, ribosomes have been popular for their passive role in the cellular processes. However, new studies indicate that they potentially regulate gene expression, including in human cells. The findings of this study lead to a further understanding of mRNA’s role and the causes of gene misregulation in human diseases.
Ribosomes serve as the site for biological synthesis of proteins. They read codons in an mRNA message to determine which amino acid is to be added to the growing polypeptide chain. This process is termed as “translation.” For your information, codons are sets of three consecutive nucleotides determining the amino acid sequence of a protein. In addition, ribosomes also act as quality control and trigger the destruction of improperly made mRNA as well.
Scientists have also come across the role of ribosomes in affecting the stability (life) of properly processed mRNAs. Thereby, they act as a key factor in modulating mRNA stability, level of mRNA, and protein production. The studies concluding these findings were carried employing organisms such as yeast, E. coli, and zebrafish. However, this study shows that ribosomes affect mRNA stability in human cell lines as well.
According to the researchers, the amount of gene expression is a combination of mRNA production (transcription) and stability. The exact amount of total mRNAs includes the amount of both mRNAs being produced and mRNAs being broken down. These findings help you to better understand how ribosomes trigger mRNA destruction, the molecular mechanism of which is still unknown.
What does the study reveal?
Just like ribosomes, molecules called “tRNAs” or “transfer RNAs” also carry out protein synthesis. They recognize codons in mRNA and provide corresponding amino acids to ribosomes. Moreover, they have a strong regulatory role in the development and in human diseases as well.
The study also enumerates how this newly discovered regulatory molecular mechanism may be related to genes associated with human diseases. Human genome sequencing and its success have revealed that individuals sometimes have a “silent mutation.” It is a change in DNA sequence and codons that don’t change the amino acid makeup of the resulting protein. This is because many amino acids are coded by multiple codons. However, the silent mutation might still have an effect if it leads to ribosomes destroying healthy mRNA.
One of the most fundamental concepts of biology is how genes are regulated and how those regulations drive cell specialization. Scientists are usually more interested in studying how post-transcription mechanisms work. In particular, they are keen to know how ribosomes trigger mRNA destruction and how they activate or recruit factors to carry out this process.
Understanding the molecular basis of how translation affects mRNA expression allows the researchers to start thinking about how mRNA translation might shape gene expression in cancer, aging, or viral infection.