Vrljicak et al. — Cell Reports
Gene expression in the endometrium changes dramatically across the menstrual cycle — but the mechanisms coordinating those changes at the cellular level have remained poorly understood. This study, published in Cell Reports, takes a high-resolution look at what's driving cycle-dependent gene activity in endometrial cells.
Using single-cell ATAC-seq (scATAC-seq), the research team mapped chromatin accessibility — essentially, which regions of the genome are physically open and available to transcription factors — across endometrial cell types at multiple points in the cycle.
What they found Temporal shifts in chromatin accessibility were found to coordinate transcription factor access to regulatory DNA elements, providing a molecular mechanism for how the endometrium switches gene programs across phases. The opening of the implantation window, in particular, coincided with a striking finding: the sequential co-option of both old and young transposable elements into the regulatory chromatin landscape of decidualizing stromal cells.
Transposable elements — once considered genomic junk — are increasingly recognized as drivers of evolutionary innovation in placental mammals. This study adds to that picture, suggesting they play an active role in fine-tuning the endometrial environment at the precise moment the window for embryo implantation opens.