The **NADK2** gene encodes an enzyme that plays a crucial role in the cellular metabolism of nicotinamide adenine dinucleotide (NAD) and its phosphorylated form, NADP. Here’s an expanded overview based on your request:

### 1. Associated Genes
NADK2 is known to have interactions with several other genes involved in metabolic pathways and mitochondrial function. Some genes of interest include:
- **NADK**: This gene encodes another form of NAD kinase that has overlapping but distinct functions.
- **ACADS (Acyl-CoA Dehydrogenase, C-2 to C-3 Short Chain)**: Mutations in NADK2 can lead to disruptions in the metabolism of fatty acids that ACADS also processes.
- **SIRTUINS (SIRT1, SIRT3, SIRT6)**: These genes are involved in NAD+ metabolism and are important for cellular responses to stress, linking NADK2 to longevity and aging processes.

### 2. Aging and Age-Related Diseases
Research has suggested that NAD+ metabolism is crucial for cellular health, especially in aging. Alterations in this pathway can contribute to several age-related diseases, such as:
- **Metabolic syndromes**: NADK2's involvement in NADP production relates to fatty acid metabolism and insulin sensitivity.
- **Neurodegenerative diseases**: Dysregulation of NAD+/NADP+ can affect neuroprotection and inflammation, both of which are critical in diseases like Alzheimer’s and Parkinson’s.
- **Cardiovascular diseases**: NADP+ influences cellular redox balance and may impact aging of the cardiovascular system.

### 3. Drug Interactions
As of now, specific drugs directly targeting NADK2 are not widely reported. However, the metabolic pathways associated with NAD+ and NADP+ indicate potential interactions with:
- **NAD+ precursors**: Such as nicotinamide riboside and nicotinamide mononucleotide, often investigated for their potential in longevity and metabolic health.
- **Poly(ADP-ribose) polymerase inhibitors**: Since those can influence cellular NAD+ levels indirectly impacting NADK2 activity.

### 4. Pathways and Biological Processes
NADK2 is involved in several important biochemical pathways and processes:
- **NADP biosynthesis**: Essential for the oxidative phase of the pentose phosphate pathway.
- **Nucleotide metabolism**: As it relates to the synthesis and recycling of NADP+.
- **Oxidative stress response**: By regulating the NADPH pool, it plays a key role in cellular defense mechanisms against oxidative damage.
- **Fatty acid metabolism**: Through its association with acyl-CoA reactions.

In summary, NADK2 is a vital gene in mitochondrial metabolism, particularly in regulating NAD and NADP levels, which have far-reaching implications in energy metabolism, aging, and related diseases. Further research continues to clarify its role and therapeutic potential against age-related conditions and metabolic disorders.