### CAPN1 Gene Overview

**Gene Symbol**: CAPN1  
**Location**: Human chromosome 11p15.5  
**Function**: CAPN1 encodes the large subunit of calpain 1, a calcium-dependent cysteine protease involved in various cellular processes such as cytoskeletal remodeling and signal transduction through limited proteolysis of substrate proteins.

### 1. Associated Genes

CAPN1 has several known interactions with various other genes. Some noteworthy gene associations include:

- **CAPN2**: Another calpain family member, functioning similarly to CAPN1 but with some distinct substrates and roles. 
- **Caspase genes (e.g., CASP3, CASP7)**: CAPN1 interacts with caspases, indicating its role in apoptosis and cell signaling pathways.
- **CTBP1**: As noted, CAPN1 cleaves this transcriptional regulator at specific sites.
- **P53**: Involved in various cellular stress responses and may be influenced by calpain activity.
- **Cytoskeletal proteins**: Interactions with various cytoskeleton-related genes reflect CAPN1's role in cytoskeletal dynamics.

### 2. Aging and Age-Related Diseases

CAPN1 has been implicated in several age-related diseases and processes, notably:

- **Neurodegeneration**: Elevated activity of calpains, including calpain 1, has been associated with neurodegenerative diseases such as Alzheimer's disease, where they are thought to contribute to apoptosis and tau protein modifications.
- **Muscle Degeneration**: In conditions like sarcopenia (age-related muscle loss), calpain activity is altered and may influence muscle protein turnover.
- **Cardiovascular Diseases**: Dysregulation of calpain activity has been linked to myocardial infarction and hypertrophy, indicating a potential role in age-related cardiovascular decline.

### 3. Drug Interactions

CAPN1 does not have specific drugs that target it directly; however, there are drug classes and compounds known to modulate calpain activity, including:

- **Calpain inhibitors**: These include compounds like SNJ-1945 and calpastatin-like peptides, which could potentially be therapeutics in conditions where calpain activity is detrimental.
- **Nonsteroidal anti-inflammatory drugs (NSAIDs)**: Some studies suggest that these may have indirect effects on calpain activity in inflammatory pathways.
  
Due diligence on specific interactions is necessary, as therapeutic approaches may change with ongoing research.

### 4. Pathways and Biological Processes

CAPN1 is involved in various biological pathways, including:

- **Caspase-Dependent Apoptosis**: It plays a role in the apoptotic signaling cascade through interaction with caspases.
- **Cell Cycle Regulation**: Calpain 1 influences various aspects of cell cycle regulation via proteolytic activity on key regulatory proteins.
- **Cytoskeletal Remodeling**: It is involved in rearranging the cytoskeletal architecture, essential for processes like cell motility, division, and differentiation.
- **Response to Stress**: Calpain 1 activity is upregulated during stress responses, highlighting its role in cellular adaptation to damage.
- **Inflammatory Response**: Research suggests it may influence signaling pathways that regulate inflammation.

### Summary

The CAPN1 gene encodes an essential protease involved in various critical cellular processes. Its interactions, particularly in aging and disease, make it a significant molecule for further research in therapeutic developments against age-related pathologies and disorders involving apoptosis and cellular signaling modifications.