### NEDD4 Gene Overview:

**Gene Symbol:** NEDD4

**Function:**  
NEDD4 (Neural Precursor Cell-Expressed Developmentally Downregulated 4) is a protein-coding gene that encodes a member of the NEDD4 family of HECT (homologous to E6-AP carboxyl terminus) ubiquitin ligases. NEDD4 plays a crucial role in the ubiquitin-proteasome system, where it facilitates protein degradation by tagging substrates with ubiquitin molecules. Its protein structure is characterized by a calcium and phospholipid binding C2 domain, several WW domains, and a C-terminal HECT domain critical for its enzymatic activity in ubiquitination.

### Additional Information:

1. **Associated Genes:** 
   - **PTEN**: Previously mentioned, regulated by NEDD4 polyubiquitination.
   - **RAPGEF2**: Ubiquitination facilitated by NEDD4.
   - **EGFR**: NEDD4 plays a role in the degradation of the EGF receptor.
   - **FGFR1**: Ubiquitination leading to receptor degradation.
   - **ERBB4**: The intracellular domain is ubiquitinated.
   - **TNK2**: Ubiquitinated by NEDD4, affecting EGF response.
   - **VPS34**: Involved in autophagy and its stability is regulated by NEDD4.
   - **USP13**: Part of a deubiquitination complex with NEDD4.

2. **Age-related Details:**
   - NEDD4 is implicated in various cancer processes, given its role in regulating tumor suppressor proteins like PTEN. Abnormalities in NEDD4 function may contribute to tumor development and progression, which can be more prevalent with aging.
   - Studies have suggested NEDD4 may influence cell senescence and longevity pathways through its interactions with age-related signaling molecules, though specific connections to aging phenotypes require further exploration.

3. **Drug Interactions:**
   - While no specific drugs have been universally established to directly target NEDD4, certain compounds that modulate ubiquitination pathways may affect its function indirectly. 
   - **Drug Classes**: 
     - Proteasome inhibitors (e.g., Bortezomib) may impact the pathways NEDD4 is involved in, through modulation of protein degradation processes.
     - Other potential anticancer agents may indirectly influence NEDD4 activity, given its role in oncogenic processes.

4. **Pathways and Biological Processes:**
   - **Ubiquitin-mediated proteolysis**: NEDD4 is a critical component of this process, tagging proteins for degradation.
   - **Receptor-mediated endocytosis**: NEDD4 ubiquitinates various receptors leading to their internalization.
   - **EGFR signaling pathway**: Involved in EGF receptor degradation, thus influencing cellular growth and proliferation.
   - **Neurite outgrowth**: NEDD4 is implicated in neuronal development and the extension of dendrites.
   - **Autophagy**: Stabilizes VPS34, promoting autophagosome formation.
   - **Cancer-related pathways**: Involved in signaling pathways that regulate tumor suppressors and oncogenes.

### Summary:
NEDD4 is an integral ubiquitin ligase influencing multiple cellular processes, especially in the context of cancer biology and receptor regulation. Its interactions, potential aging implications, and involvement in various biological pathways point to its pivotal role in cell signaling and maintenance processes.