XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells. (https://pubmed.ncbi.nlm.nih.gov/38181737/)

These scientists wanted to understand how a special type of RNA called XIST helps control the activity of genes on the X chromosome. The X chromosome is one of the chromosomes that determines if someone is a boy or a girl. In girls, one of their X chromosomes is turned off in a process called X chromosome inactivation (XCI). The scientists were curious about what XIST does when it is not turning off the X chromosome.

They studied cells called human pluripotent stem cells, which are special cells that can turn into many different types of cells in our bodies. In these stem cells, the XIST RNA was spread out across the X chromosome and not turned off. The scientists discovered that even when XIST is not turning off the X chromosome, it still affects the activity of genes on the X chromosome. It makes them less active.

But here's the surprising part: the scientists also found that XIST can also affect genes on other chromosomes called autosomes. It makes them less active too. This helps to balance the amount of gene activity between boys and girls, but it also creates differences in gene activity on the autosomes.

The scientists also noticed that the XIST RNA is spread out and affects autosomes in a temporary way when X chromosome inactivation is starting in mouse pluripotent stem cells.

So, this study tells us that XIST is not only important for turning off genes on the X chromosome, but it also has a role in controlling gene activity on other chromosomes. It helps to make sure that boys and girls have similar amounts of gene activity on the X chromosome, but it also creates differences in gene activity on other chromosomes.

Dror I., Chitiashvili T., Tan SYX., Cano CT., Sahakyan A., Markaki Y., Chronis C., Collier AJ., Deng W., Liang G., Sun Y., Afasizheva A., Miller J., Xiao W., Black DL., Ding F., Plath K. XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells. Cell. 2024 Jan 4;187(1):110-129.e31. doi: 10.1016/j.cell.2023.11.033.