Various hormones such as steroid, thyroid, sterol, and retinoid hormones, each have their specific Hormone Response Elements (HREs) on DNA. Interestingly, researchers have discovered that these HREs contain a common sequence within their structure. This finding raises questions, as it implies that a same sequence may mediate the actions of multiple hormones. However, several explanations could account for this phenomenon:
- Firstly, it is possible that varying concentrations of hormone receptors in different cell types may restrict which HREs they can bind to.
- Secondly, there may be subtle sequence differences among HREs that are challenging to detect.
- Thirdly, the availability of the ligand (hormone) could limit which HREs are activated.
- Finally, HREs may not function as isolated elements; rather, they likely interact with cis/trans regulatory elements, forming complex networks to mediate their effects. Due to these intricate interactions, researchers refer to these complexes as Hormone Response Units.
