How do steroid hormones affect gene expression?

Steroid hormones affect gene expression by binding to specific receptors and activating or repressing transcription.

Steroid hormones are lipid-soluble molecules that can easily cross the cell membrane and bind to specific receptors in the cytoplasm or nucleus of target cells. Once bound, the hormone-receptor complex can enter the nucleus and directly affect gene expression by binding to specific DNA sequences called hormone response elements (HREs) located in the promoter regions of target genes.

Depending on the specific hormone-receptor complex and the target gene, steroid hormones can either activate or repress transcription. Activated hormone-receptor complexes can recruit coactivator proteins that help to recruit RNA polymerase and initiate transcription, while repressed hormone-receptor complexes can recruit corepressor proteins that inhibit transcription.

In addition to direct effects on gene expression, steroid hormones can also affect gene expression indirectly by modulating the activity of other transcription factors or signalling pathways. For example, some steroid hormones can activate or inhibit the activity of kinases or phosphatases that regulate the activity of transcription factors such as AP-1 or NF-κB.

Overall, steroid hormones play a critical role in regulating gene expression in a wide range of physiological processes, including development, metabolism, and immune function. Understanding the mechanisms by which steroid hormones affect gene expression is therefore essential for understanding the underlying biology of these processes and developing new therapies for diseases that involve dysregulation of steroid hormone signalling.