### PRKACA Gene Overview

**Gene Symbol**: PRKACA  
**Description**: The PRKACA gene encodes a catalytic subunit of Protein Kinase A (PKA), a critical enzyme involved in various signaling pathways mediating cell metabolism, growth, and differentiation. PKA is part of a tetrameric holoenzyme composed of two regulatory subunits and two catalytic subunits, which is activated by cyclic AMP (cAMP). 

### 1. Associated Genes
While the provided summaries mention several substrate genes phosphorylated by PRKACA and pathways it interacts with, here are additional genes associated with PRKACA or involved in its biological processes:

- **RICTOR**: Involved in mTOR signaling pathway.
- **AKT1**: Regulatory interactions in cell survival and growth.
- **GSK3B**: Glycogen synthase kinase that is phosphorylated and regulated by PKA, influencing multiple pathways including metabolism and cell cycle.
- **PLCG1**: Phospholipase C gamma, which can interact with signaling pathways downstream of PKA.
- **CREB1**: The transcription factor that is phosphorylated by PKA, important for cAMP signaling.
- **MAPK1 (ERK2)**: Associated with signaling pathways that cross-talk with PKA mediated responses.

### 2. Aging and Age-Related Diseases
PRKACA has been associated with numerous cellular processes, and dysregulation of its activity is linked to various age-related conditions:

- **Cancer**: Aberrant activation of PRKACA due to mutations or structural alterations is implicated in adrenal tumors and other malignancies, which can be detected more frequently in older populations.
- **Metabolic Disorders**: PKA is involved in insulin signaling and glucose metabolism, thus, dysregulation could contribute to age-associated diseases like type 2 diabetes.
- **Neurodegenerative Diseases**: There is evidence suggesting that PKA participates in pathways involved in neuron survival and function, potentially influencing age-related cognitive decline.
- **Osteoporosis**: Age-related inhibition of osteogenic differentiation (for example, through PRKACA activity) could play a role in bone density loss associated with aging.

### 3. Drug Interactions
Several drug classes and specific compounds can modulate the activity of PRKACA, either directly or indirectly, including:

- **Phosphodiesterase inhibitors** (e.g., sildenafil): These drugs increase cAMP levels, hence indirectly activating PKA.
- **Cyclic AMP analogs** (e.g., 8-Br-cAMP): These can be used in experimental settings to study PKA function and might show therapeutic potential in various diseases.
- **Protein kinase inhibitors**: While specific inhibitors targeting PKA have yet to be widely established therapeutically, emerging selective small molecules are being investigated.
- **Antioxidants**: Some studies suggest a linkage between oxidative stress response and PKA pathways.

### 4. Pathways and Biological Processes
PRKACA is part of numerous signaling pathways and biological processes, including but not limited to:

- **cAMP Signaling Pathway**: The primary pathway that activates PKA.
- **Regulation of Cell Cycle and Apoptosis**: By regulating proteins like CDC25B and GLI.
- **Insulin Signaling Pathway**: Participates in glucose metabolism and energy homeostasis.
- **Hedgehog Signaling**: Down-regulates this critical developmental pathway influencing embryonic development and morphogenesis.
- **Regulation of Calcium Signaling**: Involved in modulation of calcium release in cardiac and other muscle cells.
- **Fatty Acid Metabolism and Lipid Homeostasis**: Affecting adipogenesis and potentially playing a role in obesity.
- **Embryonic Development**: Functioning through the modulation of cell signaling that affects differentiation and organogenesis.

Overall, PRKACA plays a multifaceted role in numerous biological functions and processes that are vital to organism development, metabolism, and responses to external stimuli. Its dysregulation is linked to serious health conditions, particularly as animals and humans age.