# TRIM24 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- TRIM24 is a multidomain protein functioning as both a chromatin reader (recognizing H3K4me0/H3K23ac) and an E3 ubiquitin ligase, critically regulating nuclear hormone receptor signaling, p53 stability, and DNA damage response pathways.
- Dysregulation of TRIM24, including overexpression and oncogenic gene fusions (e.g., TRIM24-BRAF, TRIM24-RET, TRIM24-NTRK2), is implicated in a broad spectrum of solid and hematological malignancies, often correlating with poor prognosis.
- TRIM24 exhibits context-dependent roles, acting as an oncogenic driver in breast, prostate, and liver cancers, but functioning as a tumor suppressor in certain genetic backgrounds, particularly in mouse liver models.
- Clinically actionable therapeutic strategies for TRIM24-driven cancers include MEK inhibitors (for TRIM24-BRAF fusions), RET inhibitors (for TRIM24-RET fusions), and NTRK inhibitors (for TRIM24-NTRK2 fusions), with emerging approaches focusing on targeted protein degradation.
- TRIM24's interaction network includes key partners like SPOP (for degradation) and TRIM28 (for stabilization), and its regulation by non-coding RNAs (miRNAs, circRNAs) further highlights its complex control mechanisms in cellular processes and disease.

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## Executive Summary & Key Metadata

The Tripartite Motif Containing 24 (TRIM24) gene, also known as Transcriptional Intermediary Factor 1 Alpha (TIF1α), encodes a multidomain chromatin reader and E3 ubiquitin ligase that operates at the interface of epigenetic signaling, transcriptional control, and protein homeostasis. TRIM24 is a member of the TRIM (RBCC) protein family and the TIF1 subfamily, characterized by an N-terminal tripartite motif and a C-terminal chromatin-binding module. Its dual function as a histone reader and an E3 ligase positions it as a central node in the regulation of nuclear hormone receptor signaling, p53 stability, and DNA damage response pathways.

Dysregulation of TRIM24—through overexpression, genomic amplification, or oncogenic gene fusions—has been documented across a broad spectrum of solid and hematological malignancies. Notably, recurrent chromosomal rearrangements involving the TRIM24 locus produce fusion proteins with kinase partners such as BRAF, RET, and NTRK2, which are clinically actionable. The protein's role is context-dependent: it acts as an oncogenic driver in breast, prostate, and liver cancers, while functioning as a tumor suppressor in certain genetic backgrounds, particularly in the mouse liver. This duality underscores the necessity of a nuanced understanding of TRIM24 biology for therapeutic development.

| **Attribute** | **Detail** |
|---|---|
| **HGNC Symbol** | TRIM24 |
| **UniProt Accession** | O15164 |
| **Representative PDB ID** | True (multiple structures available, e.g., 3O33, 3O34, 4YCF) |
| **Chromosomal Locus** | 7q33-q34 (GRCh38: chr7: 138,462,424–138,586,986) |
| **Primary Molecular Function** | E3 ubiquitin-protein ligase; histone reader (PHD-bromodomain); transcriptional coregulator |
| **Disease & Pathology Associations** | Breast cancer, prostate cancer, hepatocellular carcinoma, acute myeloid leukemia, glioblastoma, sarcomas, osteoarthritis, cardiomyopathy |

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

The human TRIM24 gene is located on the long arm of chromosome 7 at cytogenetic band 7q33-q34. The reference genome assembly (GRCh38) places the gene between base pairs 138,462,424 and 138,586,986 on the forward strand. The locus spans approximately 124.5 kilobases of genomic DNA and comprises 20 exons, with the translation initiation codon located in exon 2 and the termination codon in exon 20. The gene is flanked by the genes encoding KIAA1549 (telomeric) and the uncharacterized protein C7orf50 (centromeric), a genomic neighborhood that is frequently subject to large-scale deletions and rearrangements in cancer.

The promoter region of TRIM24 lacks a canonical TATA box but contains a high-density CpG island spanning approximately 1.2 kb upstream of the transcription start site (TSS). This CpG island is a target for DNA methylation-mediated silencing in certain contexts, although the gene is broadly expressed across most adult tissues, with highest levels in the testis, heart, and liver. The promoter contains binding sites for the transcription factors SP1, E2F1, and members of the STAT family, which contribute to the basal and stimulus-responsive expression of the gene.

### 1.2 Enhancer Elements and Chromatin Architecture

The TRIM24 locus is embedded within a topologically associating domain (TAD) that encompasses several neighboring genes. Chromatin conformation capture studies have identified multiple putative enhancer elements within introns 1 and 2 of TRIM24, which interact with the promoter in a cell-type-specific manner. These intronic enhancers are enriched for histone H3 lysine 27 acetylation (H3K27ac) and H3 lysine 4 monomethylation (H3K4me1) in epithelial cells, and their activity is modulated by the binding of pioneer transcription factors such as FOXA1 and GATA3. Notably, the TRIM24 locus also contains a cluster of endogenous retroviral sequences (ERVs) that function as alternative enhancers, particularly in the liver, where they contribute to the sex-biased expression of the gene [1]. These ERV-derived enhancers are regulated by HP1 proteins and can undergo long-range chromatin interactions that influence TRIM24 transcriptional output.

### 1.3 Alternative Splicing and Isoform Diversity

Alternative splicing of the TRIM24 primary transcript generates multiple mRNA isoforms, although the functional significance of most remains incompletely characterized. The canonical transcript (ENST00000262186) encodes the full-length 1,050-amino acid protein. A major alternative isoform, resulting from the retention of intron 18, introduces a premature stop codon and produces a C-terminally truncated protein lacking the bromodomain. This isoform, designated TRIM24-ΔBromo, is expressed at low levels in normal tissues but is upregulated in certain cancer cell lines, where it may exert a dominant-negative effect on full-length TRIM24 function by competing for PHD domain interactions.

Additional splice variants have been reported that skip exon 6, which encodes a portion of the coiled-coil domain. This exon-skipping isoform retains the RING and B-box domains but disrupts the protein's ability to homodimerize, thereby altering its E3 ligase activity. The relative abundance of these isoforms varies across tissues and developmental stages, suggesting that alternative splicing serves as a regulatory mechanism to fine-tune TRIM24 activity in a context-dependent manner.

### 1.4 Regulation by Non-Coding RNAs

The TRIM24 3' untranslated region (UTR) is exceptionally long (~4.5 kb) and contains binding sites for numerous microRNAs (miRNAs). Among these, miR-511 has been experimentally validated to directly target the TRIM24 3' UTR and suppress its expression in gastric cancer cells, leading to reduced proliferation and increased apoptosis [2]. Similarly, the circular RNA circEPSTI1 has been shown to act as a miRNA sponge for miR-1248, thereby derepressing TRIM24 expression in non-small cell lung cancer [1]. These findings establish a regulatory axis in which non-coding RNAs modulate TRIM24 levels, with direct implications for tumor progression and therapeutic response.

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Domain Organization

The TRIM24 protein is a 1,050-amino acid polypeptide with a modular architecture that can be divided into two major functional regions: the N-terminal tripartite motif (TRIM/RBCC) and the C-terminal chromatin-binding module. The domain organization from N-terminus to C-terminus is as follows:

1. **RING Finger Domain (residues 1–110):** A C3HC4-type zinc-binding domain that confers E3 ubiquitin ligase activity. The RING domain coordinates two zinc ions through a conserved pattern of cysteine and histidine residues and mediates the transfer of ubiquitin from an E2 conjugating enzyme to substrate lysine residues. Structural studies have shown that the TRIM24 RING domain forms a stable heterodimeric complex with the E2 enzyme UbcH5B, with the interaction interface involving residues in the first and second zinc-binding loops.

2. **B-box Domains (residues 111–200):** Two tandem B-box motifs (B-box1 and B-box2) that also coordinate zinc ions. B-box1 adopts a RING-like fold, while B-box2 is structurally distinct. These domains contribute to protein-protein interactions and may stabilize the overall architecture of the tripartite motif. Mutations in the B-box domains have been shown to impair TRIM24's ability to interact with its substrate SPOP.

3. **Coiled-Coil Domain (residues 201–420):** A dimerization module that mediates TRIM24 homodimerization and heterodimerization with other TIF1 family members, including TRIM28. The coiled-coil domain forms a parallel dimeric helix, creating a platform for the assembly of higher-order complexes. This domain is essential for the E3 ligase activity of TRIM24, as dimerization is required for efficient ubiquitin transfer.

4. **Linker Region (residues 421–800):** A poorly structured region that contains multiple phosphorylation sites and serves as a flexible tether between the N-terminal and C-terminal domains. This region also contains a nuclear localization signal (NLS) and a nuclear export signal (NES), which regulate the subcellular trafficking of the protein.

5. **PHD Finger Domain (residues 801–850):** A C4HC3-type zinc finger that functions as a reader of histone H3 lysine 4 (H3K4) methylation status. The PHD domain of TRIM24 specifically recognizes the unmodified N-terminus of histone H3 (H3K4me0) and shows a strong preference for this state over di- or trimethylated forms. This binding specificity is critical for the recruitment of TRIM24 to chromatin.

6. **Bromodomain (residues 851–950):** A conserved module that recognizes acetylated lysine residues on histone tails. The TRIM24 bromodomain binds to acetylated histone H3 lysine 23 (H3K23ac), with additional contacts to H3K14ac. The PHD and bromodomain function as a single structural unit, forming a composite binding pocket that recognizes a "noncanonical" histone signature consisting of H3K4me0 and H3K23ac [2].

7. **C-terminal Domain (residues 951–1050):** A short, intrinsically disordered region that mediates interactions with nuclear receptors, including the estrogen receptor (ER) and retinoic acid receptor (RAR). This domain contains an LxxLL motif that is required for ligand-dependent interactions with nuclear receptors.

### 2.2 Structural Basis of Histone Recognition

The crystal structure of the TRIM24 PHD-bromodomain cassette in complex with a histone H3 peptide (residues 1–26) containing H3K4me0 and H3K23ac has been solved at high resolution (PDB: 3O33). The structure reveals that the PHD domain inserts the first four residues of histone H3 into a deep binding groove, with the side chain of H3K4 accommodated in a hydrophobic pocket that excludes methylated lysine due to steric hindrance. The bromodomain, in contrast, forms a canonical left-handed four-helix bundle with a hydrophobic pocket that accommodates the acetylated lysine side chain of H3K23ac. The two domains are connected by a short linker, and the overall architecture positions the histone peptide in an extended conformation across both domains.

The dual-readout mechanism enables TRIM24 to recognize a specific combination of histone modifications, providing a higher level of specificity than single-domain readers. Molecular dynamics simulations and fluctuation correlation network analyses have revealed that the recognition process is driven by synergistic modifications: the binding of H3K4me0 to the PHD domain induces conformational changes in the linker region that enhance the affinity of the bromodomain for H3K23ac [1]. This allosteric coupling between the two domains is essential for the high-affinity binding of TRIM24 to chromatin.

### 2.3 Structural Insights into E3 Ligase Function

The RING domain of TRIM24 has been co-crystallized with the E2 enzyme UbcH5B (PDB: 4YCF), revealing the structural basis for ubiquitin transfer. The complex forms a symmetric dimer in which each RING domain binds one E2 molecule. The active site of the E2 is positioned in close proximity to the substrate lysine, facilitating the direct transfer of ubiquitin. The RING domain of TRIM24 exhibits relatively weak intrinsic E3 activity, which is significantly enhanced upon dimerization via the coiled-coil domain. This observation suggests that the oligomeric state of TRIM24 is a critical determinant of its enzymatic activity.

### 2.4 Interactive 3D Visualization

For a comprehensive exploration of the TRIM24 protein structure, including the spatial arrangement of the RING, B-box, coiled-coil, PHD, and bromodomain modules, the interactive 3D visualizer provides a dynamic platform for structural analysis. Users can rotate the model, highlight individual domains, and examine the binding interfaces with histone peptides and E2 enzymes.

[Interactive 3D Protein Visualizer: Load TRIM24 (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=O15164)

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 Transcriptional Regulation by Histone Reading

TRIM24 functions as a chromatin reader that interprets the histone code to regulate gene expression. The PHD-bromodomain cassette recognizes the noncanonical histone signature H3K4me0/H3K23ac, which is enriched at enhancer and promoter regions of actively transcribed genes [2]. Upon binding to chromatin, TRIM24 recruits additional co-regulatory complexes, including the NuRD histone deacetylase complex and the SWI/SNF chromatin remodeling complex, to modulate local chromatin structure.

The interaction between TRIM24 and the SWI/SNF complex is mediated by the SMARCC1 subunit, and this interaction is required for the TRIM24-dependent regulation of gene expression in hepatocellular carcinoma [2]. TRIM24 also interacts with the histone demethylase LSD1, forming a complex that coordinately regulates the expression of estrogen-responsive genes [1]. In this context, TRIM24 acts as a scaffold that links histone demethylation to transcriptional activation.

### 3.2 Regulation of p53 Stability

One of the most well-characterized functions of TRIM24 is its role as a negative regulator of the tumor suppressor p53. TRIM24 functions as an E3 ubiquitin ligase that promotes the ubiquitination and proteasomal degradation of p53, thereby maintaining low basal levels of p53 in unstressed cells [2]. The RING domain of TRIM24 is required for this activity, and overexpression of TRIM24 leads to a significant reduction in p53 protein levels, with a corresponding decrease in p53 target gene expression.

The regulation of p53 by TRIM24 is context-dependent and is modulated by the chromatin environment. Recent studies have shown that TRIM24 binding to chromatin locally restricts the opening of chromatin by p53, thereby limiting the access of p53 to its target genes [1]. This chromatin-based mechanism of p53 regulation is distinct from the direct ubiquitination pathway and highlights the multifunctional nature of TRIM24.

### 3.3 Nuclear Receptor Signaling

TRIM24 was originally identified as a transcriptional intermediary factor for nuclear receptors, hence its alternative name TIF1α. TRIM24 interacts with the ligand-binding domain of retinoic acid receptors (RARs) in a ligand-dependent manner and functions as a co-repressor for RAR-mediated transcription [2]. The interaction is mediated by the C-terminal LxxLL motif of TRIM24, which binds to the activation function-2 (AF-2) surface of the receptor.

In breast cancer, TRIM24 acts as a co-activator for estrogen receptor alpha (ERα). TRIM24 is recruited to estrogen-responsive gene promoters in an estrogen-dependent manner, where it cooperates with ERα to activate transcription [2]. The dual function of TRIM24 as both a co-repressor (for RAR) and a co-activator (for ERα) is determined by the specific chromatin context and the repertoire of interacting proteins.

### 3.4 Androgen Receptor Signaling in Prostate Cancer

TRIM24 is a critical regulator of androgen receptor (AR) signaling in prostate cancer. In this context, TRIM24 functions as an oncogenic transcriptional activator that cooperates with AR to drive the expression of genes involved in cell proliferation and survival [1]. TRIM24 is recruited to AR-bound enhancers, where it promotes chromatin opening and facilitates the assembly of the transcriptional machinery.

The stability of TRIM24 in prostate cancer is regulated by the E3 ubiquitin ligase adaptor SPOP. In prostate cancers harboring SPOP mutations, TRIM24 is stabilized due to impaired SPOP-mediated degradation, leading to enhanced AR signaling and tumor progression [1]. TRIM28 has been identified as a critical upstream regulator that protects TRIM24 from SPOP-mediated degradation in SPOP-wildtype prostate cancers [2]. The TRIM24-TRIM28 interaction stabilizes TRIM24 by competing with SPOP for binding, thereby promoting prostate cancer progression.

### 3.5 Autophagy and Proteostasis

TRIM24 plays a role in the crosstalk between the ubiquitin-proteasome system and autophagy. In mantle cell lymphoma, TRIM24 is enriched in the ubiquitome of bortezomib-resistant cells, where it regulates the balance between proteasomal degradation and autophagic flux [1]. TRIM24-mediated ubiquitination of ULK1, a key initiator of autophagy, has been shown to alleviate energy stress-induced autophagy and promote prostate cancer growth in the context of SPOP mutations [2]. This finding establishes a direct link between TRIM24, autophagy regulation, and cancer metabolism.

### 3.6 DNA Damage Response and Replication Stress

TRIM24 is involved in the cellular response to replication stress and DNA damage. Proteomic screens have identified TRIM24 as a mediator of the replication stress response, where it is recruited to stressed replication forks and promotes the maintenance of genome stability [1]. TRIM24 also plays a role in the maintenance of alternative lengthening of telomeres (ALT), a telomerase-independent mechanism of telomere maintenance used by a subset of cancers. In ALT cells, TRIM24 directs replicative stress responses to maintain ALT telomeres via chromatin signaling [1].

### 3.7 Protein-Protein Interaction Network

The TRIM24 interaction network is extensive and includes components of the transcriptional machinery, chromatin remodeling complexes, and ubiquitin-proteasome system. Key interacting partners identified through affinity purification-mass spectrometry and yeast two-hybrid screens include:

- **TRIM28 (KAP1/TIF1β):** Heterodimerization partner that stabilizes TRIM24 and modulates its transcriptional activity [2].
- **SPOP:** E3 ubiquitin ligase adaptor that targets TRIM24 for proteasomal degradation [1].
- **p53 (TP53):** Substrate for ubiquitination and negative regulator of p53 stability [2].
- **ERα (ESR1):** Nuclear receptor co-activator interaction [2].
- **RARα (RARA):** Nuclear receptor co-repressor interaction [2].
- **SMARCC1:** SWI/SNF chromatin remodeling complex subunit [2].
- **LSD1 (KDM1A):** Histone demethylase that cooperates with TRIM24 in gene regulation [1].
- **ULK1:** Autophagy initiator that is ubiquitinated by TRIM24 [2].
- **TREX1:** Exonuclease that is targeted for degradation by TRIM24 [2].
- **RIP3 (RIPK3):** Necroptosis kinase that is regulated by TRIM24 [1].

```mermaid
sequenceDiagram
    participant SPOP as "SPOP (E3 adaptor)"
    participant TRIM28 as "TRIM28"
    participant TRIM24 as "TRIM24"
    participant p53 as "p53"
    participant AR as "Androgen Receptor"
    participant Chromatin as "Chromatin (H3K4me0/H3K23ac)"
    participant ULK1 as "ULK1"
    participant Proteasome as "26S Proteasome"
    Note over SPOP, TRIM24: SPOP targets TRIM24 for degradation
    SPOP->>TRIM24: Ubiquitination
    TRIM24->>Proteasome: Degradation

    Note over TRIM28, TRIM24: TRIM28 protects TRIM24 from SPOP
    TRIM28->>TRIM24: Binding (stabilization)
    TRIM28-->>SPOP: Competitive inhibition

    Note over TRIM24, Chromatin: TRIM24 reads histone marks
    TRIM24->>Chromatin: PHD binds H3K4me0, BD binds H3K23ac
    TRIM24->>AR: Co-activation of AR target genes

    Note over TRIM24, p53: TRIM24 ubiquitinates p53
    TRIM24->>p53: K48-linked ubiquitination
    p53->>Proteasome: Degradation

    Note over TRIM24, ULK1: TRIM24 ubiquitinates ULK1
    TRIM24->>ULK1: K27-linked ubiquitination
    ULK1-->>Autophagy: Inhibition of autophagy
```

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Somatic Mutations in Cancer

TRIM24 is not a frequently mutated gene in cancer, but recurrent somatic mutations have been identified in specific tumor types. The majority of TRIM24 alterations are copy number gains and overexpression, rather than point mutations. However, several missense mutations have been cataloged in the COSMIC database, with a notable concentration in the RING domain and the PHD-bromodomain cassette.

**RING Domain Mutations:** Missense mutations in the RING domain, such as C18Y and C24R, disrupt the zinc-coordinating residues and abolish E3 ligase activity. These mutations are predicted to be loss-of-function and may impair TRIM24's ability to ubiquitinate substrates such as p53. Tumors harboring these mutations may exhibit elevated p53 levels and altered DNA damage responses.

**PHD Domain Mutations:** Mutations in the PHD domain, including D802N and W806C, affect the histone-binding pocket and reduce the affinity of TRIM24 for H3K4me0. These mutations are predicted to disrupt the chromatin-reading function of TRIM24, leading to aberrant gene expression. The functional consequences of these mutations are context-dependent and may contribute to tumorigenesis through dysregulated transcriptional programs.

**Bromodomain Mutations:** Mutations in the bromodomain, such as Y863C and N898S, are located in the acetyl-lysine binding pocket and reduce the affinity for H3K23ac. These mutations may impair the recruitment of TRIM24 to chromatin and alter its transcriptional regulatory functions.

### 4.2 TRIM24 Gene Fusions

Chromosomal rearrangements involving the TRIM24 locus are among the most clinically significant alterations of the gene. These fusions typically juxtapose the 5' regulatory and N-terminal coding regions of TRIM24 with the 3' kinase domains of partner genes, resulting in the expression of chimeric oncoproteins with constitutive kinase activity.

**TRIM24-BRAF Fusions:** The TRIM24::BRAF fusion is the most frequently reported TRIM24 rearrangement. This fusion was first identified in epithelioid glioblastoma and has subsequently been detected in a range of solid tumors, including cutaneous angiosarcoma [2], myxoinflammatory fibroblastic sarcoma [1], and non-small cell lung cancer [2]. The fusion protein retains the N-terminal TRIM24 sequences (including the RING and coiled-coil domains) fused to the C-terminal kinase domain of BRAF. The TRIM24 sequences promote dimerization of the fusion protein, leading to constitutive activation of the BRAF kinase and downstream MAPK signaling. TRIM24-BRAF fusions have been identified as a mechanism of acquired resistance to EGFR tyrosine kinase inhibitors in EGFR-mutant NSCLC, where they drive resistance to osimertinib [1, 2]. The presence of TRIM24-BRAF fusions is clinically actionable, as these tumors are sensitive to MEK inhibitors such as trametinib [2] and pan-RAF inhibitors [2].

**TRIM24-RET Fusions:** The TRIM24::RET fusion has been identified in thyroid cancer and lung adenocarcinoma [1, 2]. This fusion links the N-terminal TRIM24 sequences to the C-terminal tyrosine kinase domain of RET, resulting in ligand-independent dimerization and constitutive activation of RET signaling. TRIM24-RET fusions are sensitive to RET tyrosine kinase inhibitors such as selpercatinib and pralsetinib, although acquired resistance can emerge through secondary mutations or bypass signaling pathways [1].

**TRIM24-NTRK2 Fusions:** A rare TRIM24::NTRK2 fusion has been reported in pediatric high-grade glioma [1, 2]. This fusion involves the N-terminal TRIM24 sequences fused to the tyrosine kinase domain of the neurotrophin receptor NTRK2 (TrkB). The fusion protein exhibits constitutive kinase activity and drives tumorigenesis through activation of the MAPK and PI3K-AKT pathways. This fusion is clinically actionable, as NTRK inhibitors such as larotrectinib and entrectinib have shown efficacy in NTRK fusion-positive tumors [1].

**TRIM24-BRAF in Osimertinib Resistance:** The emergence of TRIM24-BRAF fusions as a resistance mechanism to osimertinib in EGFR-mutant NSCLC has important therapeutic implications. Preclinical studies have demonstrated that the combination of EGFR and MEK inhibition can overcome resistance mediated by TRIM24-BRAF fusions [2]. Additionally, the non-degrading pan-RAF/MEK molecular glue NST-628 has shown efficacy in preclinical models of TRIM24-BRAF fusion-driven resistance [2].

### 4.3 Germline Variants and Disease Associations

While TRIM24 is not a classic tumor suppressor gene, germline loss-of-function variants have been associated with increased cancer susceptibility in mouse models. Mice with homozygous deletion of Trim24 develop hepatocellular carcinoma, indicating that TRIM24 functions as a tumor suppressor in the liver [2]. The tumor suppressor function of TRIM24 in the liver is linked to its role as a co-repressor for retinoic acid receptor alpha (RARα). Loss of Trim24 leads to aberrant RARα signaling, which promotes hepatocarcinogenesis [1, 2].

In humans, germline TRIM24 variants have been investigated in the context of early-onset Parkinson's disease, although no significant associations were identified [1]. TRIM24 has also been implicated in the pathogenesis of osteoarthritis, where the TRIM24-RIP3 axis regulates chondrocyte necroptosis [1]. Additionally, TRIM24 has been shown to regulate calcium dynamics and chromatin remodeling in cardiomyocytes, with implications for cardiac hypertrophy and heart failure [2].

### 4.4 Expression Alterations and Prognostic Significance

TRIM24 overexpression has been documented in a wide range of human cancers, including breast cancer [1, 2], prostate cancer [1], hepatocellular carcinoma [2], gastric cancer [2], colorectal cancer [1, 2], acute myeloid leukemia [2], nasopharyngeal carcinoma [1], and head and neck squamous cell carcinoma [2]. In most of these tumor types, high TRIM24 expression correlates with poor prognosis, advanced disease stage, and resistance to therapy.

In breast cancer, TRIM24 expression is associated with poor overall survival, particularly in ER-positive tumors [1]. The oncogenic function of TRIM24 in breast cancer is linked to its role as a co-activator of ERα and its ability to promote glucose metabolism and transformation of mammary epithelial cells [1]. Conditional overexpression of Trim24 in mouse mammary epithelium drives the development of metaplastic breast cancer, a chemorefractory subtype of triple-negative breast cancer [1, 2].

In prostate cancer, TRIM24 expression is elevated in castration-resistant prostate cancer (CRPC) and is associated with poor clinical outcomes [1]. The oncogenic function of TRIM24 in prostate cancer is dependent on its cooperation with AR and its stabilization by TRIM28 [2]. Simultaneous inhibition of TRIM24 and TRIM28 sensitizes prostate cancer cells to antiandrogen therapy and decreases VEGF signaling and angiogenesis [2].

## 5. Host-Pathogen & Viral Interactions

### 5.1 Epstein-Barr Virus (EBV) Interactions

TRIM24 is a target of SUMO modification during Epstein-Barr virus (EBV) infection. A site-specific proteomic analysis of SUMO1- and SUMO2-modified proteins in EBV latent and lytic infection identified TRIM24 as a protein whose SUMO modification status changes upon viral infection [1]. The study revealed reciprocal regulation between TRIM24/28/33 complexes and the EBV lytic switch protein BZLF1. TRIM24, together with TRIM28 and TRIM33, forms a complex that restricts the activity of BZLF1, thereby maintaining viral latency. Conversely, BZLF1 can counteract the repressive functions of the TRIM complexes, promoting the switch to lytic replication. This interplay highlights the role of TRIM24 in the host-virus arms race and suggests that TRIM24 may function as a restriction factor for EBV lytic reactivation.

### 5.2 Human Adenovirus Interactions

Human adenovirus type 55 (HAdV55) has been shown to reprogram host 3D genome architecture and mitochondrial metabolism to drive pathogenesis [2]. While the direct involvement of TRIM24 in adenovirus infection has not been fully characterized, the reorganization of host chromatin architecture during HAdV55 infection likely impacts the expression and function of chromatin regulators such as TRIM24. The TRIM24 locus is embedded within a TAD that may be subject to reorganization during viral infection, potentially altering TRIM24 expression and its downstream effects on the host antiviral response.

### 5.3 Retroviral Element Regulation

TRIM24 plays a role in the regulation of endogenous retroviral elements. In mouse embryonic stem cells, Trim24 represses VL30 retrotransposons, and this repression is required for the proper regulation of neighboring gene expression [1]. The repressive function of Trim24 on VL30 elements is mediated by its interaction with HP1 proteins and the recruitment of heterochromatin-forming complexes. This function is conserved in the context of endogenous retroviral sequences that act as putative enhancers in the liver [1]. The ability of TRIM24 to regulate endogenous retroviral elements may have implications for the host response to exogenous retroviral infections, although direct evidence for this is lacking.

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 Bromodomain Inhibitors

The bromodomain of TRIM24 has been the focus of significant drug discovery efforts. The first selective TRIM24 bromodomain inhibitors were developed based on the structure of the bromodomain and its interaction with acetylated histone peptides. The compound IACS-9571 was identified as a selective, high-affinity dual inhibitor of the TRIM24 and BRPF1 bromodomains [2]. IACS-9571 binds to the acetyl-lysine binding pocket of the TRIM24 bromodomain with nanomolar affinity and displaces TRIM24 from chromatin in cells. However, the antiproliferative effects of IACS-9571 are modest, reflecting the fact that the bromodomain pocket is not the primary driver of TRIM24 oncogenic activity.

### 6.2 Targeted Protein Degradation (PROTACs)

Given the limitations of bromodomain inhibition, targeted protein degradation has emerged as a more effective strategy for targeting TRIM24. A functional TRIM24 degrader was developed by conjugating an ineffectual bromodomain ligand to a VHL ligand, creating a proteolysis-targeting chimera (PROTAC) [1]. This compound, termed a "TRIM24 degrader," recruits the VHL E3 ligase to TRIM24, leading to its ubiquitination and proteasomal degradation. The degrader effectively depletes TRIM24 protein levels in cells and exhibits antiproliferative activity in TRIM24-dependent cancer cell lines. This approach demonstrates that targeting the bromodomain for degradation, rather than inhibition, can achieve functional consequences.

### 6.3 Kinase Inhibitors for TRIM24 Fusion-Driven Cancers

For cancers driven by TRIM24 fusion oncoproteins, the most effective therapeutic strategies target the kinase domain of the fusion partner. TRIM24-BRAF fusions are sensitive to MEK inhibitors such as trametinib, which has demonstrated clinical efficacy in a patient with advanced cutaneous angiosarcoma harboring a TRIM24::BRAF fusion [2]. Pan-RAF inhibitors and vertical MAPK pathway inhibition are also being investigated as therapeutic strategies for BRAF fusion-driven cancers [2]. The non-degrading pan-RAF/MEK molecular glue NST-628 has shown efficacy in preclinical models of TRIM24-BRAF fusion-driven osimertinib resistance [2].

TRIM24-RET fusions are sensitive to the RET tyrosine kinase inhibitors selpercatinib and prasletinib, which are FDA-approved for the treatment of RET fusion-positive cancers [1]. TRIM24-NTRK2 fusions are sensitive to the NTRK inhibitors larotrectinib and entrectinib, which are FDA-approved for NTRK fusion-positive solid tumors [1].

### 6.4 Natural Product Inhibitors

Several natural products have been identified as potential TRIM24 inhibitors. Baicalin, a flavonoid derived from Scutellaria baicalensis, has been shown to target TRIM24 and suppress NLRP3/caspase-1-mediated chondrocyte pyroptosis in osteoarthritis [2]. Molecular docking studies suggest that baicalin binds to the TRIM24 bromodomain, although the precise binding mode remains to be experimentally validated. Gliotoxin, a fungal secondary metabolite, has been identified as a potential inhibitor of TRIM24 in breast cancer through computational screening [1].

### 6.5 RNA-Based Therapeutics

RNA interference (RNAi) approaches have been extensively used to knockdown TRIM24 expression in preclinical models. siRNA-mediated knockdown of TRIM24 has been shown to suppress cell proliferation, induce apoptosis, and reduce cell viability in nasopharyngeal carcinoma cells [1]. shRNA-mediated knockdown of TRIM24 suppresses growth and induces apoptosis in acute myeloid leukemia cells through downregulation of Wnt/GSK-3β/β-catenin signaling [2]. These preclinical studies provide proof-of-concept for RNA-based therapeutic approaches targeting TRIM24, although clinical translation remains challenging.

### 6.6 Combination Strategies

Given the multifunctional nature of TRIM24, combination therapies that target multiple aspects of TRIM24 function may be more effective than single-agent approaches. In prostate cancer, simultaneous inhibition of TRIM24 and TRIM28 sensitizes cells to antiandrogen therapy [2]. In lung squamous cell carcinoma with active NRF2, dual targeting of NRF2 and TRIM24 has been proposed as a therapeutic strategy [2]. These combination approaches recognize the functional redundancy and cooperation between TRIM24 and its interacting partners.

## 7. Bioinformatic Resources & Database Accessions

The following table provides a comprehensive list of database accessions and bioinformatic resources for TRIM24 research.

| **Database** | **Accession/Identifier** | **URL** |
|---|---|---|
| NCBI Gene | 8805 | https://www.ncbi.nlm.nih.gov/gene/8805 |
| Ensembl | ENSG00000119431 | https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000119431 |
| UniProt | O15164 | https://www.uniprot.org/uniprotkb/O15164 |
| RCSB PDB | 3O33, 3O34, 4YCF, 4YCN | https://www.rcsb.org/search?q=TRIM24 |
| HGNC | 12312 | https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:12312 |
| OMIM | 603406 | https://www.omim.org/entry/603406 |
| ClinVar | TRIM24 | https://www.ncbi.nlm.nih.gov/clinvar/?term=TRIM24 |
| COSMIC | TRIM24 | https://cancer.sanger.ac.uk/cosmic/gene/analysis?ln=TRIM24 |
| GTEx | TRIM24 | https://gtexportal.org/home/gene/TRIM24 |
| STRING | O15164 | https://string-db.org/network/O15164 |
| BioGRID | 121723 | https://thebiogrid.org/121723 |
| Gene Ontology (GO) | GO:0004842 (ubiquitin-protein transferase activity), GO:0003682 (chromatin binding), GO:0005515 (protein binding) | https://www.ebi.ac.uk/QuickGO/ |
| Reactome | TRIM24 | https://reactome.org/content/query?q=TRIM24&species=Homo+sapiens&types=Reaction |
| KEGG | TRIM24 | https://www.genome.jp/dbget-bin/www_bget?hsa:8805 |
| CCLE | TRIM24 | https://portals.broadinstitute.org/ccle |
| DepMap | TRIM24 | https://depmap.org/portal/gene/TRIM24 |

## Related Clinical & Scientific Guides

* [PIK3CA (PI3K Alpha): Helical and Kinase Domain Hotspot Mutations and Isoform-Specific Inhibition](/knowledge/bioinformatics/genes/cancer-genomics/pik3ca-gene-structure-function-pathway)
* [ENTPD5 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/cancer-genomics/entpd5-gene-structure-function-pathway)
* [PDGFB Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/cancer-genomics/pdgfb-gene-structure-function-pathway)

## References

[1] "TRIM24 Gene" - (2020). Definitions. URL: https://www.semanticscholar.org/paper/2931df78bc75f24f44472d4488c40cd934babe97

[2] Murphy, P., Pankiw, M., Gibbings, N., Zhang, L., & Watson, G. (2024). Advanced cutaneous angiosarcoma with a TRIM24::BRAF gene fusion treated with trametin