### HTR1E Gene Overview

#### Gene Summary
**HTR1E** (5-Hydroxytryptamine Receptor 1E) encodes a member of the serotonin receptor family and is primarily involved in G protein-coupled receptor signaling. The receptor functions as a 5-hydroxytryptamine (serotonin) receptor and also has roles in binding to various psychoactive substances and alkaloids. Upon ligand binding, HTR1E undergoes a conformational change that activates G proteins, leading to modulations in the activity of downstream effectors like adenylate cyclase. This signaling pathway is characterized by the inhibition of adenylate cyclase activity, which reduces the levels of cAMP in the cell.

### 1. Associated Genes
While the HTR1E gene itself is primarily known for its role in serotonin signaling, it may be associated with several other genes involved in neurotransmission, mood regulation, and other signaling pathways. Some of the notable genes that have been studied in relation to HTR1E include:

- **HTR1A**: A prominent serotonin receptor that may interact functionally in serotonin signaling pathways.
- **HTR2A**: Another serotonin receptor that plays a role in mood and anxiety disorders.
- **SLC6A4** (Serotonin transporter): Regulates serotonin levels and may influence the receptor's function by modulating serotonin availability.
- **GNAI** (G protein alpha inhibitory): Related to the G protein signaling that HTR1E triggers upon activation.

### 2. Aging and Age-Related Diseases
While specific studies linking HTR1E directly to aging or age-related diseases are limited, serotonin signaling is known to play a role in various physiological processes that change with age. Some pertinent associations are:

- **Cognitive Decline**: Alterations in serotonin signaling, including potential changes in HTR1E function, have been associated with age-related cognitive disorders, including depression and anxiety.
- **Neurodegenerative Diseases**: Impairments in serotonin receptor signaling have been observed in conditions like Alzheimer's disease, suggesting possible involvement of HTR1E in these pathological processes.
- **Mood Disorders**: The role of serotonin in mood regulation implies that HTR1E could potentially be implicated in age-related mood disorders, such as late-life depression.

### 3. Drug Interactions
HTR1E is known to interact with several drugs and classes of drugs, primarily those targeting serotonin systems. Some examples include:

- **Selective Serotonin Reuptake Inhibitors (SSRIs)**: Medications such as fluoxetine and sertraline that enhance serotonin signaling may affect HTR1E activity indirectly.
- **Triptans**: Such as sumatriptan, which are typically used to treat migraines and act on serotonin receptors including HTR1E.
- **Alkaloids**: Compounds like psilocybin and other psychoactive substances that bind to 5-HT receptors, including HTR1E.
- **Antipsychotics**: Certain atypical antipsychotic medications that impact serotonin receptors may also interact with HTR1E.

### 4. Pathways and Biological Processes
HTR1E is involved in several key biological pathways and processes including:

- **G Protein-Coupled Receptor Signaling Pathway**: Critical for transmitting signals from outside the cell to initiate various cellular responses.
- **Regulation of cAMP Metabolic Process**: Via inhibition of adenylate cyclase, influencing cellular energy and signaling.
- **Neurotransmitter Receptor Activity**: Particularly in the context of serotonin signaling affecting mood, emotion, and cognition.
- **Cellular Response to Hormones**: Given its role in signaling cascades that modulate cellular responsiveness to hormonal signals.
  
Overall, the HTR1E gene plays a crucial role in serotonin signaling, influencing numerous biological processes, and is implicated in pharmacological interactions, particularly with substances affecting mood and cognition.