Steroid receptor coactivator

Definition

A steroid receptor coactivator is a protein that enhances the transcriptional activity of nuclear hormone receptors, particularly steroid hormone receptors. These coactivators play a critical role in mediating the effects of steroid hormones by facilitating the recruitment of additional proteins necessary for gene expression, ultimately influencing various physiological processes such as metabolism, development, and reproduction.

5 Must Know Facts For Your Next Test

1. Steroid receptor coactivators can modify chromatin structure to enhance the accessibility of DNA for transcription.
2. They often act in conjunction with other cofactors to form large multiprotein complexes that are essential for effective gene regulation.
3. Coactivators can be recruited by various post-translational modifications of steroid hormone receptors, such as phosphorylation and acetylation.
4. Different steroid receptor coactivators can have distinct tissue-specific functions, impacting how steroid hormones influence various biological pathways.
5. The dysregulation of steroid receptor coactivators has been implicated in several diseases, including cancer and metabolic disorders.

Review Questions

• How do steroid receptor coactivators interact with nuclear receptors to influence gene expression?
  • Steroid receptor coactivators interact with nuclear receptors by binding to their activation domains once the receptors are activated by their respective steroid hormones. This interaction enhances the recruitment of additional transcriptional machinery necessary for effective gene expression. By modifying chromatin structure and facilitating the assembly of transcriptional complexes, these coactivators play a pivotal role in regulating target gene expression in response to hormonal signals.
• Discuss the functional differences between steroid receptor coactivators and corepressors in regulating nuclear receptor activity.
  • Steroid receptor coactivators enhance nuclear receptor activity by promoting gene transcription, while corepressors perform the opposite function by inhibiting transcription. Coactivators achieve their effect through mechanisms such as chromatin remodeling and recruiting RNA polymerase II, whereas corepressors bind to nuclear receptors and prevent the recruitment of coactivators and the transcriptional machinery. This balance between coactivators and corepressors is crucial for maintaining appropriate gene expression levels in response to hormonal signals.
• Evaluate the implications of dysregulated steroid receptor coactivator activity in disease states such as cancer or metabolic disorders.
  • Dysregulation of steroid receptor coactivator activity can lead to inappropriate gene expression patterns that contribute to disease states like cancer and metabolic disorders. For example, overexpression of certain coactivators may drive oncogenic pathways, promoting tumor growth and survival. In metabolic disorders, altered coactivator function can disrupt normal hormonal signaling, leading to insulin resistance or obesity. Understanding these implications highlights the importance of steroid receptor coactivators as potential therapeutic targets in treating these diseases.

Related terms

Nuclear Receptors: A class of proteins that function as transcription factors, which are activated by ligands such as steroid hormones and regulate the expression of specific genes.

Corepressor: A protein that inhibits the transcriptional activity of nuclear receptors by preventing the recruitment of coactivators and other transcriptional machinery.

Transcription Factors: Proteins that bind to specific DNA sequences and regulate the transcription of genes, playing a key role in cellular processes such as growth, differentiation, and response to external signals.