### KLHL21 Gene Overview

The **KLHL21** gene, also known as **Kelch-like 21**, encodes a protein that participates in various cellular processes, including chromosomal organization and cytokinesis. It is a member of the cullin-RING E3 ubiquitin ligase complex, which plays an essential role in protein ubiquitination and subsequent degradation through the proteasome, albeit not always leading to degradation as noted for certain substrates like AURKB.

### 1. Associated Genes
The KLHL21 gene is primarily known for its interaction with the following genes and proteins:

- **CUL3**: Cullin 3, a core component of the Cullin-RING E3 ubiquitin ligase complex.
- **RBX1**: Ring-box 1, the RING finger protein that facilitates the transfer of ubiquitin from E2 ubiquitin-conjugating enzymes to substrate proteins.
- **AURKB**: Aurora kinase B, a crucial serine/threonine kinase involved in chromosome alignment and segregation during cell division.
- **BUB1**: Budding uninhibited by benzimidazoles 1, involved in monitoring chromosome segregation.

These associations highlight the role of KLHL21 in cell cycle regulation and the fidelity of chromosome segregation.

### 2. Aging and Age-related Diseases
As of now, there are limited specific studies directly linking KLHL21 to aging or age-related diseases. However, given its role in cell division, abnormalities in KLHL21 function or expression could contribute to processes commonly associated with aging, such as:

- **Tumorigenesis**: Deregulation of cell cycle genes, including those involved in ubiquitination processes, could play a role in cancer development, which is more prevalent in aging populations.
- **Genomic Instability**: The impact of improper chromosome alignment and segregation could lead to age-related chromosomal abnormalities.

Further research may elucidate the potential implications of KLHL21 in aging processes.

### 3. Drug Interactions
Currently, specific drugs or drug classes directly interacting with KLHL21 are not well established. However, potential research avenues could include:

- **Proteasome inhibitors**: As KLHL21 is involved in ubiquitin-protein transferase activity, drugs that inhibit the proteasome might influence its functional outcomes, although the direct interaction has not been specifically characterized.

Future research may provide insights into more direct pharmacological interactions.

### 4. Pathways and Biological Processes
KLHL21 is involved in several important biological pathways, including:

- **Ubiquitin-mediated proteolysis**: The biochemical process through which proteins are marked for degradation via ubiquitination.
- **Cytokinesis**: The final step of cell division where two daughter cells are formed.
- **Chromosome Passenger Complex (CPC) Pathway**: Involvement in the proper functioning and localization of the CPC, essential for ensuring accurate segregation of chromosomes during cell division.
- **Cell Cycle Regulation**: Specifically active during anaphase of mitosis to facilitate chromosome alignment and proper cell division.

### Conclusion
The KLHL21 gene plays a critical role in cell cycle regulation and protein ubiquitination, contributing to essential processes such as cytokinesis and chromosome alignment. While direct links to aging and specific pharmacological interactions remain to be fully explored, its functions underscore its importance in maintaining cellular integrity and stability. Further research is essential to delineate its full scope of influence in health and disease.