### GPR155 Gene Overview
The GPR155 gene encodes a protein that plays a crucial role in cholesterol sensing and regulation of cellular processes through the mTORC1 signaling pathway. GPR155 is implicated in processes related to cognition and cellular metabolism.

### 1. Associated Genes
GPR155 interacts or is associated with several other genes that are part of the mTOR signaling pathway and cholesterol metabolism. While specific names may not be explicitly mentioned in the summaries provided, the following genes are directly involved in similar pathways:
- **GATOR1 Complex Genes**: This includes genes such as **DEPDC5, NPRL2**, and **NPRL3** that are part of the GATOR1 complex which regulates mTORC1 signaling.
- **KICSTOR Complex Genes**: This may include genes like **ATG13** and **KICSTOR** components which interact with mTORC1.
- **Other Cholesterol Metabolism Genes**: There may be associations with genes like **SREBF1** and **ABCA1** which are crucial in cholesterol homeostasis.

### 2. Aging and Age-Related Diseases
While specific literature directly linking GPR155 to aging or age-related diseases is limited, the gene’s involvement in cholesterol binding and mTOR signaling places it within contexts important to aging. The mTOR signaling pathway is well-known for its role in regulating cellular growth and metabolism, which decreases with age and can contribute to age-related diseases like:
- **Neurodegenerative Diseases**: Given its role in cognition and potential interactions in brain pathways, aberrations in GPR155 may influence conditions like Alzheimer's or Parkinson’s disease.
- **Metabolic Disorders**: Cholesterol metabolism is often disrupted in aging populations, raising the possibility that GPR155 could have implications in metabolic syndromes or cardiovascular diseases.

### 3. Drug Interactions
As of October 2023, explicit information about specific drugs or drug classes that directly target GPR155 is not widely documented. However, compounds that influence cholesterol metabolism or mTOR pathways may indirectly affect its activity. Some classes of relevant drugs could include:
- **Statins**: Cholesterol-lowering agents that might influence GPR155 indirectly through modulating overall cholesterol levels in cells.
- **mTOR Inhibitors**: Drugs like rapamycin and its analogs might have relevance due to their effect on the mTOR pathway, but specific targeting of GPR155 by these drugs is not confirmed.

### 4. Pathways and Biological Processes
GPR155 is involved in several key biological pathways:
- **mTOR Signaling Pathway**: It primarily regulates the activation of mTORC1 signaling based on cellular cholesterol levels.
- **Lipid Metabolism**: By functioning as a cholesterol sensor, GPR155 plays a role in lipid homeostasis and metabolism.
- **Exosome Pathway**: The extracellular exosome localization suggests a potential role in cell communication and signaling processes.

In summary, GPR155 is a cholesterol-binding protein that acts as a pivotal regulator of mTORC1 signaling, linking cholesterol levels to cell growth and function. Further research may elucidate more about its roles in aging and potential therapeutic interactions.