MDM4 (MDMX)

MDM4 (MDMX)

MDM4 (also known as MDMX or MDM4) is a critical negative regulator of p53 and plays an important role in genome stability, cell cycle control, and tumor suppression. It is a member of the MDM family of proteins (MDM1, MDM2, MDM4) that regulate p53 activity.

Gene Overview

<div class="infobox infobox-gene">
| Property | Value |
|----------|-------|
| Gene Symbol | MDM4 (MDMX) |
| Full Name | MDM4 Proto-Oncogene |
| Chromosomal Location | 1q32.1 |
| NCBI Gene ID | 4193 |
| OMIM | 602673 |
| Ensembl | ENSG00000198625 |
| UniProt | O15151 |
| Associated Diseases | Retinoblastoma, Li-Fraumeni syndrome, breast cancer, melanoma, neurodegeneration |
</div>

Overview

MDM4 (MDMX)

MDM4 (also known as MDMX or MDM4) is a critical negative regulator of p53 and plays an important role in genome stability, cell cycle control, and tumor suppression. It is a member of the MDM family of proteins (MDM1, MDM2, MDM4) that regulate p53 activity.

Gene Overview

<div class="infobox infobox-gene">
| Property | Value |
|----------|-------|
| Gene Symbol | MDM4 (MDMX) |
| Full Name | MDM4 Proto-Oncogene |
| Chromosomal Location | 1q32.1 |
| NCBI Gene ID | 4193 |
| OMIM | 602673 |
| Ensembl | ENSG00000198625 |
| UniProt | O15151 |
| Associated Diseases | Retinoblastoma, Li-Fraumeni syndrome, breast cancer, melanoma, neurodegeneration |
</div>

Overview

MDM4 is a human gene whose product mDM4 is a nuclear protein that contains a p53-binding domain and functions primarily as a transcriptional repressor["@toledo2007"]:. Variants in MDM4 have been implicated in Cancer, Neurodegeneration. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.

Normal Function

MDM4 is a nuclear protein that contains a p53-binding domain and functions primarily as a transcriptional repressor[@toledo2007]:

p53 Regulation

• Direct Binding: MDM4 binds to p53 transactivation domain, inhibiting p53-mediated gene activation
• Protein Stability: Unlike MDM2, MDM4 does not ubiquitinate p53; instead it stabilizes p53 protein
• Feedback Regulation: p53 activates MDM4 expression, creating a balanced regulatory loop

Cell Cycle Control

• G1/S Transition: MDM4 overexpression promotes G1/S cell cycle progression
• S-Phase Entry: Modulates E2F1 activity for proper S-phase entry
• Checkpoint Response: Negatively regulates p53-dependent cell cycle arrest

DNA Damage Response

• ATM Activation: Involved in ATM/ATR-mediated DNA damage response
• Chk2 Phosphorylation: Modulates checkpoint kinase activation
• Genomic Stability: Loss leads to increased genomic instability

Disease Associations

Cancer

• Oncogenic Driver: MDM4 amplification is common in various cancers[@toledo2021]
• Retinoblastoma: Germline MDM4 mutations predispose to retinoblastoma
• Melanoma: Frequently overexpressed in melanoma
• Breast Cancer: MDM4 overexpression correlates with poor prognosis

Neurodegeneration

• Alzheimer's Disease: MDM4 is upregulated in AD brains and may affect neuronal [apoptosis](/entities/apoptosis)
• P53-mediated Neurodegeneration: Altered MDM4/p53 balance affects neuronal survival
• DNA Repair: MDM4 modulates DNA repair efficiency in [neurons](/entities/neurons)

Expression Pattern

MDM4 shows tissue-specific expression:

• High Expression: Embryonic tissues, testis, thymus
• Moderate Expression: Brain, heart, skeletal muscle
• Low/Restricted Expression: Most adult tissues

Therapeutic Implications

Cancer Therapy

• MDM4 Inhibitors: Small molecules targeting MDM4-p53 interaction in development
• Combination Therapy: MDM4 inhibitors with chemotherapy or radiation

Research Directions

• Understanding MDM4's role in neuronal apoptosis
• Targeting MDM4 in neurodegeneration

Cross-Links

• [TP53](/genes/tp53) - Primary target
• [MDM2](/genes/mdm2) - Family member
• [Cell Cycle](/mechanisms/cell-cycle) - Pathway
• [Apoptosis](/mechanisms/apoptosis) - Pathway

See Also

• [Cell Cycle](/mechanisms/cell-cycle)
• [Apoptosis](/mechanisms/apoptosis)

External Links

• [Ensembl: ENSG00000198625](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000198625)
• [NCBI Gene: MDM4](https://www.ncbi.nlm.nih.gov/gene/?term=MDM4)
• [GeneCards: MDM4](https://www.genecards.org/cgi-bin/carddisp.pl?gene=MDM4)
• [OMIM: MDM4](https://omim.org/search?search=MDM4)
• [Allen Brain Atlas: MDM4](https://human.brain-map.org/microarray/search/show?search_term=MDM4)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving MDM4 (MDMX) discovered through SciDEX knowledge graph analysis: