Development of a Bioluminescent High-Throughput Screening Assay for Nicotinamide Mononucleotide Adenylyltransferase (NMNAT).
Level 5 - mechanism / opinion, no new human data
In vitro assay development and chemical screen
PubMed 31583955 · doi:10.1177/2472555219879644
What was done
Researchers developed a 384-well bioluminescent enzymatic assay using Photinus pyralis ATP-dependent luciferase to measure NMNAT1 activity (forward and reverse production of NAD+ from NMN+ and ATP) and assess time dependence and substrate competition. The assay was used to screen 912 small molecules from the National Cancer Institute (NCI) Mechanistic Diversity Set II and Approved Oncology Set VI at 20 µM against recombinant NMNAT1.
What was found
The screen identified 20 compounds producing >35% inhibition at 20 µM. Mechanistic follow-up determined that 7 hits were time-dependent inhibitors. The most potent hit, 2,3-dibromo-1,4-naphthoquinone, inhibited the forward and reverse reactions with IC50 values of 0.76 µM and 0.26 µM, respectively, and exhibited competitive inhibition with both NMN and ATP.
Why it matters
This establishes an HTS-compatible bioluminescent format to identify and mechanistically classify novel small-molecule modulators of NAD+ biosynthesis, an enzyme pathway relevant to neurodegenerative diseases and cancer therapeutics.
Limits
The study is restricted to in vitro biochemical testing against recombinant NMNAT1 without cellular, pharmacokinetic, or in vivo validation. Compound screening was limited to a relatively small library (912 molecules), and potential off-target effects or direct luciferase interference require careful consideration in downstream applications.
Cited by
- contradicts In cellular biochemistry, two NMN molecules are put together to form NAD inside a cell.