### PPP2R2D Gene Overview

The **PPP2R2D** gene encodes the regulatory subunit B of protein phosphatase 2A (PP2A), specifically termed PR55-delta. It plays a crucial role in regulating cell cycle processes, especially in controlling entry into and exit from mitosis. Its activity varies throughout the cell cycle, being high in interphase and suppressed during mitosis due to interactions with specific inhibitors.

### 1. Associated Genes

While the summaries provided focus heavily on the PPP2R2D gene itself, it is associated with multiple other genes that are part of the PP2A complex or involved in cell cycle regulation. Some of these include:

- **PPP2R1A**: The A regulatory subunit of PP2A.
- **PPP2CA**: The catalytic subunit of PP2A, also involved in diverse cellular processes.
- **ENSA** and **ARPP19**: Inhibitors of PP2A activity, particularly during mitosis.
- **CDK1**: Cyclin-dependent kinase 1, which regulates cell cycle progression and interacts with PP2A.
  
Additional partners and substrates may also include genes involved in signaling pathways, such as **AKT1** or **MAPK1**, owing to the regulatory role of PP2A.

### 2. Aging or Age-Related Diseases

While direct studies specifically linking PPP2R2D to aging or age-related diseases may be limited, the role of protein phosphatase 2A in cellular signaling and mitotic regulation implicates it in age-related processes. Dysregulation of PP2A activity has been observed in several age-associated diseases, including:

- **Cancer**: Altered PP2A activity is linked to various cancers, indicating a potential role in tumor progression and cellular aging.
- **Neurodegeneration**: Abnormal PP2A activity has been associated with neurodegenerative diseases, including Alzheimer's disease, implicating it in the regulation of pathways affecting cellular senescence.

Research into the impact of PPP2R2D on aging specifically remains an active area of investigation, especially regarding its involvement in cellular stress responses and regulation of longevity-associated signaling pathways.

### 3. Known Drug Interactions

While specific drugs targeting PPP2R2D have not been extensively documented, there are a few classes of compounds known to affect PP2A activity broadly:

- **PP2A Activators**: Compounds like FTY720 (Fingolimod) are known to activate PP2A, which can indirectly influence PPP2R2D function.
- **Inhibitors of Phosphorylation**: Certain inhibitors that target kinase activity (such as CDK inhibitors) could affect the regulatory dynamics of PPP2R2D by altering its interaction with phosphorylated substrates.

No specific drugs are directly marketed for targeting PPP2R2D alone, but the modulation of general PP2A activity through pharmacological means suggests potential therapeutic implications.

### 4. Pathways and Biological Processes

PPP2R2D is involved in several critical biological processes and signaling pathways, including:

- **Cell Cycle Regulation**: Participation in the exit of mitosis and coordination of cell cycle transitions through dephosphorylation of key substrates, such as cyclins and CDKs.
- **Apoptosis**: Regulation of apoptotic signaling pathways, possibly through interactions with various phosphoproteins involved in cell survival and death.
- **Signal Transduction**: Involvement in multiple signaling pathways including those related to growth factor signaling, like the AKT and MAPK pathways, owing to its function as a phosphatase regulating protein substrate interactions.

PPP2R2D's role as part of the PP2A complex underscores its significance in maintaining cell homeostasis and function across various biological contexts. 

In summary, the PPP2R2D gene plays a vital regulatory role in the cell cycle and has implications in aging and disease states, with various associated genes, potential drug interactions, and pathways contributing to its function.