### NRG3 Gene Overview

**Gene Symbol:** NRG3  
**Gene Family:** Neuregulin gene family  
**Function:** Encodes neuregulin 3, a ligand for ERBB3 and ERBB4 tyrosine kinase receptors, involved in various signaling pathways critical for cell functions such as proliferation and differentiation.

### 1. Associated Genes
In addition to ERBB3 and ERBB4, NRG3 has associations with:

- **NRG1**: Another member of the neuregulin family, which has roles in similar pathways related to neurodevelopment and cell signaling.
- **SHC1**: An adaptor protein that can facilitate signaling pathways downstream of the ERBB receptors.
- **PIK3CA and PIK3R1**: Components of the PI3K signaling pathway, which may be activated upon NRG binding to ERBB4.
- **AKT1**: A downstream target of PI3K signaling crucial for cell survival and metabolism.

### 2. Aging and Age-Related Diseases
**Aging:** Research indicates that neuregulins, including NRG3, may play a role in neuroprotection and the maintenance of neuronal health. Changes in NRG signaling may be implicated in age-related neuronal degeneration.

**Age-related Diseases:**
- **Schizophrenia and Schizoaffective Disorders:** Genetic studies have highlighted NRG3 as a susceptibility locus.
- **Neurodegenerative Diseases:** Altered levels of NRG signaling pathways have been implicated in conditions like Alzheimer’s disease, where neuron survival is compromised.

### 3. Drug Interactions
While specific pharmaceuticals directly targeting NRG3 are limited, drugs affecting the ERBB signaling pathways can indirectly influence NRG3 activity. Some relevant drug classes might include:

- **ERBB Inhibitors**: Such as Monoclonal Antibodies targeting ERBB receptors (e.g., Trastuzumab) or Tyrosine Kinase Inhibitors (e.g., Lapatinib).
- **Neuroprotective Agents**: Compounds that might modulate neurotrophic factors, affecting NRG signaling indirectly.

### 4. Pathways and Biological Processes
NRG3 is involved in several critical biological processes and signaling pathways, including:

- **Neurodevelopment**: Acts in neurogenesis and neural differentiation through interactions with ERBB4.
- **Cell Proliferation and Migration**: Influences cellular responses during development, particularly in mammary tissue and the central nervous system.
- **Apoptotic Signaling**: May contribute to mediating survival signals, especially for oligodendrocytes.
- **Synaptic Plasticity and Higher Cognitive Functions**: Implicated in synaptic transmission and modulation of neuronal networks.

### Summary
The NRG3 gene encodes a growth factor that plays pivotal roles in neuronal and mammary differentiation, demonstrating significance in both normal development and various neuropsychiatric disorders. Ongoing research aims to elucidate its complete impact on aging and potential therapeutic targets for associated conditions.