Bromodomain-containing protein 4, bromodomain 1 (BRD4-BD1)

Bromodomain-containing protein 4, bromodomain 1 (BRD4-BD1) is the first of two highly conserved N-terminal bromodomains in the BRD4 protein, a key member of the Bromodomain and Extra-Terminal (BET) family. It functions as an epigenetic reader that recognizes and binds to acetylated lysine residues on histone tails, particularly H4K5ac and H4K8ac, as well as on various non-histone proteins (UniProt P52732; NIH PMC5505533). This binding anchors BRD4 to chromatin, facilitating the recruitment of transcriptional machinery, including the Mediator complex and the positive transcription elongation factor b (P-TEFb), to promote gene expression (Wikipedia; PubMed 31215391). BRD4-BD1 is particularly critical for the transcription of key oncogenes such as MYC, making it a high-priority target in oncology for treating hematologic malignancies and solid tumors (NIH PMC7082114). In addition to its role in cancer, BRD4-BD1 is involved in regulating inflammatory gene networks and maintaining the integrity of the blood-brain barrier (NIH PMC11641443). Small-molecule inhibitors, such as JQ1 and OTX015, competitively bind to the acetyl-lysine binding pocket of BD1, thereby displacing BRD4 from chromatin and suppressing the expression of downstream target genes (PubMed 32193348). While many current inhibitors are pan-BET agents that target both BD1 and BD2, the development of BD1-selective inhibitors like GSK778 aims to achieve more precise therapeutic effects with a potentially improved safety profile (BenchChem). Clinical use of these inhibitors is often limited by side effects such as thrombocytopenia and gastrointestinal distress, which are thought to arise from the broad physiological roles of BET proteins (NIH PMC7835111).

Other names

BRD4HUNK1MCAPFSHRG4HUNKICAPBromodomain-containing protein 4 (BD1)

Competitive inhibition of acetyl-lysine binding to the bromodomain pocket, preventing recruitment of transcriptional machinery to chromatin.