Every cell in our body has a “just right” size.
If cells grow too large or too small, the consequences can be serious, contributing to conditions such as anemia, cancer, and developmental disorders.
Despite its importance, scientists have struggled for decades to understand how cells control their size. Now, a new discovery has revealed an unexpected answer hidden in a part of our DNA once thought to do nothing at all.
In a study published in Nature Communications, researchers at The Hospital for Sick Children, also known as SickKids, have identified the first non-coding gene that can directly control cell size.
The gene, called CISTR-ACT, belongs to a class of genetic material known as long non-coding RNA.
Unlike traditional genes, non-coding genes do not make proteins. Instead, they produce RNA molecules that help regulate how other genes behave.
These genes are part of the non-coding genome, which makes up about 98% of our DNA and was long dismissed as “junk.” This new research adds to growing evidence that this vast genetic landscape plays a crucial role in keeping our cells and bodies healthy.
CISTR-ACT was already known to be linked to rare genetic diseases affecting cartilage, but its role in controlling cell size had never been shown.
Using advanced gene-editing tools such as CRISPR and powerful computational methods, the researchers examined how this gene behaves in different cell types and organisms.
They found that CISTR-ACT acts like a growth regulator. When the gene was reduced or removed in experimental models, cells grew larger than normal.
Red blood cells became oversized, and changes appeared in brain structure that closely matched what has been observed in human patients. When researchers increased the amount of CISTR-ACT, cells became smaller. This clear cause-and-effect relationship confirmed that the gene directly controls cell size.
The team also discovered how CISTR-ACT does its job. It helps guide a protein called FOSL2 to specific genes that are involved in cell growth, structure, and how cells stick to one another.
This interaction is especially important in tissues such as the brain and bone marrow, where precise cell size is critical for normal development and function.
What makes the discovery particularly striking is that the same effect was seen across different species and cell types. This suggests that the role of CISTR-ACT is evolutionarily conserved, meaning it has been important for a very long time.
Researchers say the findings open new directions for medical science. Understanding how cell size is controlled could eventually lead to more targeted treatments for diseases where cell growth goes wrong. It also raises the possibility that other non-coding genes may be quietly controlling essential processes we have yet to uncover.
Far from being genetic filler, the non-coding genome is proving to be a powerful regulator of life at the cellular level—and CISTR-ACT is the first clear example of its role in controlling cell size.
Source: KSR.
