Unusual X chromosome inactivation maintenance in female alveolar type 2 cells is correlated with increased numbers of X-linked escape genes and sex-biased gene expression.
Level 5 - mechanism / opinion, no new human data
Preclinical laboratory study using mouse and human cell models without clinical trial data.
PubMed 36638790 · doi:10.1016/j.stemcr.2022.12.005
What was done
Researchers evaluated X chromosome inactivation (XCI) maintenance, epigenetic markers, and sex-specific transcriptomic profiles in male and female alveolar type 2 (AT2) cells from human and mouse models.
What was found
The inactive X chromosome in human and mouse AT2 cells lacked robust canonical Xist RNA clouds and showed reduced enrichment of heterochromatic modifications. In mouse AT2 cells, approximately 68% of expressed X-linked genes (including Ace2) escaped XCI, accompanied by broad genome-wide expression differences between male and female AT2 cells.
Why it matters
These findings identify a potential epigenetic mechanism for sex-biased differences in respiratory physiology and diseases, such as COVID-19 and pulmonary fibrosis, driven by high rates of X-chromosome gene escape in regenerative lung cells.
Limits
The abstract does not state the exact sample sizes or the number of human and animal donors analyzed. As an in vitro and ex vivo mechanistic study, the findings do not directly measure clinical disease outcomes or therapeutic responses in patients.
Cited by
- supports The ACE2 gene is located on the X chromosome and escapes X-inactivation, leading to higher ACE2 levels in women.