### PLXNB3 Gene Overview

**Gene Symbol:** PLXNB3  
**Location:** Chromosome 3, P21.31  
**Protein Family:** Plexin family

**Function:**  
PLXNB3 encodes a receptor for the semaphorin 5A (SEMA5A) and plays significant roles in various cellular processes, including axon guidance, cell migration, and invasive growth. The protein is involved in signaling pathways that stimulate neurite outgrowth and promote cell adhesion properties through Ca²⁺/Mg²⁺-dependent mechanisms. In glioma cells, activation of PLXNB3 by SEMA5A leads to structural changes in the cytoskeleton, inhibiting cell migration and invasion by affecting focal adhesions and stress fiber dynamics.

### 1. Associated Genes

While the summaries provided focus on PLXNB3’s interaction with SEMA5A, several other genes and their interactions also play a role in its signaling pathways:

- **RAC1:** A member of the Rho family of GTPases involved in mediating cytoskeletal dynamics and cell motility.
- **ARHGDIA:** Functions in inhibiting RAC1 activity, which is essential for the effects on cell migration and adhesion when PLXNB3 is activated.
- **PLXNA1:** Another member of the plexin family that shares functional pathways with PLXNB3.
- **PTEN:** A tumor suppressor that may interact with pathways involving PLXNB3 during cell growth and survival signaling.

### 2. Aging and Age-Related Diseases

While specific studies directly associating PLXNB3 with aging or age-related diseases are limited, its roles in cell migration and growth can contribute to a variety of age-related conditions:

- **Cancer:** Dysregulation of cell migration and invasion is a hallmark of cancer; thus, PLXNB3 may be relevant in understanding gliomas and other tumors, whose incidence increases with age.
- **Neurodegenerative Disorders:** Given its role in neuronal growth and migration, PLXNB3 may play a part in neurodegenerative processes or in the maintenance of neural structures during aging.
- **Vascular Health:** As it relates to cell migration and adhesion, aberrant signaling could impact processes such as atherosclerosis or other vascular aging-related issues.

### 3. Drug Interactions 

As of the latest available information, there are no specific drugs or drug classes explicitly mentioned that directly act on PLXNB3. However, given its involvement in cancer and cellular migration, drugs targeting similar pathways, such as those inhibiting RAC1 or other components of the cytoskeletal signaling pathway, could be relevant.

### 4. Pathways and Biological Processes

PLXNB3 is associated with several key biological pathways:

- **Semaphorin Signaling Pathway:** A critical pathway for regulating neuronal development, axon guidance, and cell signaling related to migration and adhesion.
- **Regulation of Actin Cytoskeleton:** Through its interactions with small GTPases like RAC1, PLXNB3 plays a role in the reorganization of the actin cytoskeleton.
- **Cell Adhesion and Migration:** Aspects of tumor biology are tied to its ability to influence these cellular processes.
- **Neurite Outgrowth:** Implications in neural connectivity and structural integrity in the nervous system.

### Conclusion

PLXNB3 is a vital gene in the plexin family, critically involved in axon guidance, migration, and invasion processes. While its specific interactions with drugs need more exploration, its pathway connections suggest its relevance in cancer biology and possibly in neurodegenerative conditions related to aging. Further studies could illuminate its comprehensive role in these processes.