P300/CBP

Definition

p300/CBP refers to two closely related transcriptional co-activators, p300 and CREB-binding protein (CBP), which play essential roles in the regulation of gene expression in eukaryotic cells. These proteins are involved in various cellular processes by facilitating the assembly of transcriptional machinery and modifying chromatin structure, thus enhancing the transcription of specific genes in response to various signals.

5 Must Know Facts For Your Next Test

1. p300/CBP is known for its histone acetyltransferase activity, which modifies histones and facilitates a more relaxed chromatin structure, making DNA more accessible for transcription.
2. These co-activators interact with various transcription factors, enabling them to enhance the expression of genes in response to extracellular signals such as hormones and growth factors.
3. Mutations or dysregulation of p300/CBP have been associated with several diseases, including cancer and congenital disorders, highlighting their importance in normal cellular function.
4. p300 and CBP can also recruit additional proteins, such as chromatin remodeling complexes, to further aid in the transcriptional activation process.
5. They play a critical role in cellular signaling pathways, integrating various signals and translating them into changes in gene expression that are crucial for processes like differentiation and development.

Review Questions

• How do p300/CBP enhance the activity of transcription factors during gene expression?
  • p300/CBP enhance transcription factor activity by acting as co-activators that facilitate the assembly of the transcriptional machinery at gene promoters. They achieve this through their histone acetyltransferase activity, which leads to histone modification and an open chromatin structure. This allows for easier access of RNA polymerase II and other necessary proteins to the DNA, thereby promoting increased levels of transcription.
• What role does histone acetylation by p300/CBP play in regulating chromatin structure and gene expression?
  • Histone acetylation by p300/CBP is crucial for regulating chromatin structure because it neutralizes the positive charge on histones, reducing their affinity for negatively charged DNA. This results in a more relaxed chromatin configuration that is associated with active gene transcription. Consequently, this modification allows transcription factors and RNA polymerase II easier access to the promoter regions of target genes, leading to enhanced expression.
• Evaluate the implications of p300/CBP dysregulation in human diseases, including potential mechanisms and outcomes.
  • Dysregulation of p300/CBP has significant implications for human diseases, particularly cancer and developmental disorders. For example, mutations in these co-activators can lead to aberrant gene expression patterns that promote uncontrolled cell growth or inhibit normal differentiation processes. The altered activity of p300/CBP may also affect cellular responses to external signals, resulting in resistance to therapies or progression of disease. Understanding these mechanisms opens up potential avenues for targeted treatments that could rectify the misregulation of these important co-activators.

Related terms

Transcription Factors: Proteins that bind to specific DNA sequences to regulate the transcription of target genes by promoting or inhibiting the recruitment of RNA polymerase.

Histone Acetylation: The process of adding acetyl groups to histone proteins, leading to a more open chromatin structure that promotes gene transcription.

RNA Polymerase II: An enzyme responsible for synthesizing messenger RNA (mRNA) from DNA templates during the transcription process in eukaryotic cells.