### PPARD Gene Overview

**Gene Symbol:** PPARD  
**Gene Location:** Chromosome 6 (6p21.2)  

**Function:**
The PPARD gene encodes the peroxisome proliferator-activated receptor delta (PPARδ), a crucial member of the nuclear hormone receptor superfamily. This receptor functions primarily as a transcription factor that regulates the expression of genes involved in lipid metabolism, glucose homeostasis, and energy expenditure. PPARδ enhances fatty acid oxidation and regulates the peroxisomal beta-oxidation pathway. 

#### 1. **Associated Genes:**
While multiple genes are influenced by or interact with PPARD, some notable genes include:

- **PPARA (Peroxisome proliferator-activated receptor alpha):** Involved in fatty acid oxidation and lipid metabolism.
- **PPARG (Peroxisome proliferator-activated receptor gamma):** Plays a role in adipogenesis and insulin sensitivity.
- **ACOX1 (Acyl-CoA oxidase 1):** A key enzyme in the beta-oxidation of fatty acids.
- **FABP4 (Fatty acid-binding protein 4, also known as aP2):** Involved in lipid metabolism and storage.
- **SREBF1 (Sterol regulatory element-binding protein 1):** Involved in the regulation of lipid biosynthesis.

#### 2. **Connection to Aging and Age-Related Diseases:**
PPARD’s role in lipid metabolism can be pertinent to aging, as changes in lipid profiles and energy metabolism are observed with age. Some of the associations include:

- **Metabolic Dysfunction:** Alterations in PPARδ activity may contribute to age-related metabolic disorders, such as obesity and type 2 diabetes.
- **Cognitive Decline:** Research indicates a potential role for PPARδ in promoting myelination, which could be relevant to neurodegenerative diseases.
- **Cancer:** Variability of PPARD expression in colorectal cancer may suggest its influence on cancer risk or progression, tying into age-related increases in cancer incidence.

#### 3. **Drug Interactions:**
PPARD can interact with several drugs or drug classes, particularly those that are designed to activate the PPAR pathway:

- **Fibrates:** A class of hypolipidemic agents (e.g., fenofibrate, gemfibrozil) that activate PPARα but may also exhibit some cross-activation of PPARδ.
- **Thiazolidinediones (TZDs):** Primarily activate PPARγ but have been reported to also engage PPARδ under certain contexts.
- **PPAR Modulators:** Synthetic ligands such as GW501516, a selective PPARδ agonist, are known to activate this receptor specifically and are often investigated in metabolic disease research.

#### 4. **Pathways and Biological Processes:**
PPARD is involved in several critical pathways and biological processes, including:

- **Fatty Acid Metabolism:** Regulates genes involved in both the synthesis and oxidation of fatty acids.
- **Inflammatory Response:** PPARD modulates the expression of genes associated with inflammation, potentially impacting chronic inflammatory conditions.
- **Cell Proliferation and Differentiation:** Implicated in the proliferation of keratinocytes and myelination processes, influencing skin health and neurological function.
- **Energy Homeostasis:** Involved in the regulation of energy balance, linking nutrition and metabolic processes.

### Conclusion
The PPARD gene plays a multifaceted role in various biological processes, particularly in lipid metabolism and energy homeostasis. Its interactions with other genes and potential implications in aging and diseases highlight its significance in health and disease. Understanding PPARD’s functions and mechanisms may provide insights into therapeutic approaches for metabolic disorders, cancer, and neurodegenerative conditions.