### E2F3 Gene Overview

**Gene Symbol**: E2F3  
**Location**: Chromosome 6p22.3

**Function**: E2F3 encodes a transcription factor critical in regulating the cell cycle, particularly in the transition from G1 to S phase. Through binding to DP proteins, E2F3 recognizes specific DNA motifs in gene promoters, influencing the expression of genes involved in cell proliferation and DNA replication. It interacts with the retinoblastoma protein (pRB), which is essential for the modulation of cell cycle progression.

### 1. Associated Genes
While the summary mentions the retinoblastoma protein (RB1), E2F3 is also associated with several other genes involved in similar pathways. These include:
- **E2F1 and E2F2**: Other members of the E2F transcription factor family.
- **DP1 and DP2**: Interaction partners that are essential for E2F function.
- **CCNE1 (Cyclin E1)**: Regulates the transition from G1 to S phase.
- **CDK2 (Cyclin-dependent kinase 2)**: Collaborates with cyclins to promote progression through the cell cycle.
- **CACNA1 (Calcium Voltage-Gated Channel Subunit Alpha1)**: Involved in signaling pathways that may interact with E2F3 regulation.

### 2. Age-Related Associations
E2F3 has been implicated in cellular senescence and tumorigenesis, making it relevant to aging and age-related diseases. It plays a significant role in the regulation of genes related to cellular proliferation and has been observed to have altered expression and activity in various age-related conditions, such as:
- **Cancer**: Changes in E2F3 expression can lead to uncontrolled cell division, contributing to tumor progression and malignancy, a common factor in aging populations.
- **Neurodegeneration**: There is emerging evidence suggesting dysregulation of cell cycle proteins like E2F3 in neurodegenerative diseases, potentially linking it to aging.

### 3. Drug Interactions
While there may not be specific drugs that directly target E2F3, several drug classes have been noted to have effects on its associated pathways:
- **CDK Inhibitors** (e.g., Palbociclib): Targeting cyclin-dependent kinases involved in cell cycle regulation, which E2F3 is part of.
- **Retinoblastoma Protein Pathway Modulators**: Compounds that affect the retinoblastoma pathway indirectly influence E2F3 activity.
- **Chemotherapeutic Agents**: Drugs that work by interfering with DNA replication and cell cycle processes may indirectly affect the functions of E2F3.

### 4. Pathways and Biological Processes
E2F3 is involved in numerous signaling pathways and biological processes, including but not limited to:
- **Cell Cycle Regulation**: E2F3 is pivotal in controlling the transcription of genes necessary for cell cycle progression, notably from G1 to S phase.
- **DNA Replication**: It regulates genes that ensure proper DNA synthesis and replication.
- **Apoptosis**: E2F3 can influence pathways related to programmed cell death, especially in contexts where cell proliferation is aberrant.
- **Cellular Growth and Proliferation**: E2F3 has roles in promoting cellular growth through gene activation pathways.
- **Regulation of Metabolism**: It is involved in processes that influence metabolic functions, including adipogenesis inhibition.

### Summary
E2F3 is a crucial transcription factor influencing the cell cycle and associated with various cancer pathologies and potentially relevant to aging and age-related disorders. Its interactions with additional genes, involvement in significant biological processes, and associations with therapeutic targets reflect its critical role in cellular proliferation mechanisms.