CST-polymerase alpha-primase solves a second telomere end-replication problem. (https://pubmed.ncbi.nlm.nih.gov/38418884/)

These scientists were studying a process that happens in our cells to protect the ends of our chromosomes, which are like the shoelaces at the end of our DNA strands. They found that there are two main issues that can happen when our cells try to copy the ends of these chromosomes.

The first issue is when the part of the chromosome called the G-rich strand gets shorter during the copying process. This can be fixed by a special enzyme called telomerase, which adds more of the G-rich part back on to keep the chromosome ends from getting too short.

The second issue they discovered is related to the C-rich part of the chromosome. When our cells copy this part, sometimes it doesn't get fully duplicated, which can cause problems. To solve this, another group of proteins called CST-Polalpha-primase helps to fill in the missing parts of the C-rich strand during the copying process.

In their experiments, the scientists found that when cells didn't have the CST-Polalpha-primase proteins, the C-rich part of the chromosome got shorter over time. This showed that these proteins are important for maintaining the length of the chromosome ends.

Overall, the scientists concluded that our cells have two main challenges when copying chromosome ends, and they rely on telomerase and CST-Polalpha-primase to keep the G-rich and C-rich parts intact, respectively.

Takai H., Aria V., Borges P., Yeeles JTP., de Lange T. CST-polymerase alpha-primase solves a second telomere end-replication problem. Nature. 2024 Feb 28. doi: 10.1038/s41586-024-07137-1.