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Principal Investigator: Gerta N/A Hoxhaj
Organization: UT SOUTHWESTERN MEDICAL CENTER
Fiscal Year: 2024
Award: $328,000
Funding agency: National Institute of General Medical Sciences
SUMMARY: To grow and proliferate, cells need to fulfill three key metabolic demands: increased biosynthesis,
sufficient energy supply, and maintenance of redox homeostasis. The latter demand is particularly important for
sustained growth, because increased rate of cellular metabolic activity during cell proliferation results in elevated
levels of reactive oxygen species (ROS), which can have detrimental effects on cell growth. Nicotinamide
adenine dinucleotide phosphate (NADPH) is a principal supplier of reducing power for biosynthesis of
macromolecules and protection against oxidative stress. The total cellular pool of NADPH is regulated by the
activity of NAD kinases (NADK), enzymes that catalyze the phosphorylation of NAD+ to NADP+, the rate-limiting
substrate for NADPH production. Mammalian cells express two NAD kinases, cytosolic NADK, and mitochondrial
NADK2, which generate compartment-specific reducing power. Recently, we discovered that the activity of
NADK is stimulated by the phosphoinositide 3-kinase (PI3K) - Akt pathway to boost the NADP(H) production for
cell growth, but the importance of NADK2 and the overall role of mitochondrial NADPH in cell growth has yet to
be established. Mutations in NADK2 have been observed in patients with various neurological and
developmental disorders. Therefore, defining the key functions of NADK2 and mitochondrial NADP(H) is critical
and relevant to human health. This proposal builds on our finding that decreasing mitochondrial NADP(H) levels
through depletion of NADK2 renders cells uniquely proline auxotroph. Cells with NADK2 deletion fail to
synthesize proline and rely on exogenous proline for their growth. Proline is critical for protein synthesis, and,
unexpectedly, for nucleotide synthesis, in NADK2-deficient cells. We propose three Specific Aims to establish
the functions of NADK2 and mitochondrial NADP(H) that are essential for cell growth and proliferation and
relevant for proliferative diseases and NADK2 deficiency in humans. In Aim 1, we propose to define the molecular
mechanisms by which NADK2 and mitochondrial NADPH support proline biosynthesis and evaluate the effects
of NADK2 patient mutations on proline synthesis. In Aim 2, we will determine the mechanisms of how NADK2
deficiency and reduced proline abundance affect flux through the de novo and salvage nucleotide synthesis
pathways. In Aim 3, we will assess the requirement of NADK2 and mitochondrial NADPH for tumor growth and
evaluate the therapeutic potential of targeting NADK2 in combination with dietary restriction of proline. This
proposal will establish the primary functions of mitochondrial NADP(H) and NADK2 that are essential for cell
growth and proliferation, thereby informing us on new therapeutic strategies to combat proliferative diseases and
NADK2 deficiency in humans.
Terms: <1H-Purin-6-amine><Active Oxygen><Adenine><Affect><Anabolism><Antioxidants><Autoregulation><Biochemical><Biology><Biomass><Cancers><Cell Body><Cell Growth in Number><Cell Multiplication><Cell Proliferation><Cell Protection><Cells><Cellular Expansion><Cellular Growth><Cellular Metabolic Process><Cellular Proliferation><Coenzyme II><Coupled><Cytoprotection><D-Glucose><Data><Degenerative Neurologic Disorders><Development><Dextrose><Disease><Disorder><Drug Metabolic Detoxication><Drug Metabolic Detoxification><Energy Supply><Enzyme Gene><Enzymes><Exhibits><Future><Generalized Growth><Genetic Alteration><Genetic Change><Genetic defect><Gln><Glucose><Glutamine><Goals><Growth><Health><Health Benefit><Homeostasis><Human><Human Cell Line><Hypoxanthines><Inositide Phospholipids><Inositol Phosphoglycerides><Inositol Phospholipids><Isotopes><Kinases><Knock-out><Knockout><L-Glutamine><L-Proline><Lipids><Maintenance><Malignant Neoplasms><Malignant Tumor><Mammalian Cell><Mass Photometry/Spectrum Analysis><Mass Spectrometry><Mass Spectroscopy><Mass Spectrum><Mass Spectrum Analyses><Mass Spectrum Analysis><Measurement><Mediating><Metabolic><Metabolic Drug Detoxications><Metabolism of Toxic Agents><Methods><Mitochondria><Modern Man><Molecular><Mutation><NAD phosphate><NAD(H) phosphate><NAD+ kinase><NADH phosphate><NADP><NADPH><Nervous System Degenerative Diseases><Nervous System Diseases><Nervous System Disorder><Neural Degenerative Diseases><Neural degenerative Disorders><Neurodegenerative Diseases><Neurodegenerative Disorders><Neurologic><Neurologic Degenerative Conditions><Neurologic Disorders><Neurologic Manifestations><Neurologic Signs and Symptoms><Neurologic Symptoms><Neurological><Neurological Disorders><Neurological Manifestations><Neurological Signs and Symptoms><Nicotinamide-Adenine Dinucleotide Phosphate><Nucleotide Biosynthesis><Nucleotide Synthesis><Nucleotides><Oxidation-Reduction><Oxidative Stress><Oxygen Radicals><Pathway interactions><Patients><Phenotype><Phosphatidyl Inositol><Phosphatidylinositols><Phosphoinositides><Phosphorylation><Phosphotransferase Gene><Phosphotransferases><Physiological Homeostasis><Pro-Oxidants><Production><Proliferating><Proline><Protein Biosynthesis><Protein Phosphorylation><PtdIns><Purines/Pyrimidines/Nucleotides/Nucleic Acids Metabolism><Q Levoglutamide><Q. Levoglutamide><Reactive Oxygen Species><Redox><Ribosomal Peptide Biosynthesis><Ribosomal Protein Biosynthesis><Ribosomal Protein Synthesis><Role><Science><Source><Supplementation><Supporting Cell><Symptoms><Testing><Therapeutic><Therapeutic Intervention><Tissue Growth><Transphosphorylases><Triphosphopyridine Nucleotide><Vitamin B4><Withdrawal><biosynthesis><cell growth><cell metabolism><cellular metabaolism><cofactor><combat><cytoprotective><degenerative diseases of motor and sensory neurons><degenerative neurological diseases><detoxification><developmental><developmental disease><developmental disorder><diet restriction><dietary restriction><enzyme biosynthesis><experiment><experimental research><experimental study><experiments><gene synthesis><genome mutation><in vivo><intervention therapy><macromolecule><malignancy><mitochondrial><mutant><neoplasm/cancer><neural manifestation><neurodegenerative illness><neurological disease><new therapeutic approach><new therapeutic intervention><new therapeutic strategies><new therapy approaches><new treatment approach><new treatment strategy><novel therapeutic approach><novel therapeutic intervention><novel therapeutic strategies><novel therapy approach><nucleotide metabolism><ontogeny><oxidation reduction reaction><pathway><protein synthesis><restricted diet><social role><tumor><tumor growth>