Doig 2019 bioRxiv
|Doig CD, Zelinska AE, Oakey LA, Fletcher RS, El Hassan Y, Garten A, Cartwright D, Heising S, Tennant DA, Watson D, Adamski J, Lavery GG (2019) Induction of the nicotinamide riboside kinase NAD+ salvage pathway in skeletal muscle of H6PDH KO mice. bioRxiv doi: https://doi.org/10.1101/567297 .|
Abstract: Hexose-6-Phosphate Dehydrogenase (H6PDH) is the only known generator of the pyridine nucleotide NADPH from NADP+ in the Endoplasmic/Sarcoplasmic Reticulum (ER/SR). However, its ability to influence cell wide pyridine biosynthesis and metabolism is unclear.
Skeletal muscle from H6PDH Knockout mice (H6KO) and Wild type controls (WT) was subject to metabolomic assessment and pathway analysis. NAD boosting was performed through intraperitoneal injection of Nicotinamide Riboside (NR) (400mg/kg) twice daily for 4 days. Mice were culled and skeletal muscle tissue collected the next day. Double knockout mice were generated through to breeding of H6KO with NRK2 knockout mice. These mice were assessed for NAD levels and ER stress response.
H6KO skeletal muscle shows significant changes in the pathway regulating NAD+ biosynthesis with the Nicotinamide Riboside Kinase 2 gene (NRK2) being the most elevated gene. Assessment of the metabolic impacts of this dysregulation showed decreases in mitochondrial respiration and Acylcarnitine metabolism. Pharmacologically boosting NAD+ levels with NR had no significant impact over ER stress or Acetyl-CoA metabolism. A duel H6-NRK2 KO mouse exhibited changes in NAD+ levels but no overt change in metabolism compared to the H6KO mouse.
This work shows a relationship between ER/SR status and wider muscle cell metabolism. The utility of NAD+ boosting to skeletal muscle is demonstrated however, it is also evident that the extent of cellular stress and/or REDOX status may overcome any beneficial impact.
• Keywords: Hexose-6-Phosphate Dehydrogenase, Endoplasmic/Sarcoplasmic Reticulum, Skeletal muscle, Nicotinamide Riboside, Nicotinamide Adenine Dinucleotide • Bioblast editor: Plangger M • O2k-Network Lab: UK Birmingham Lavery GG
Labels: MiParea: Respiration, Genetic knockout;overexpression
Organism: Mouse Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue Enzyme: Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase
Coupling state: LEAK, OXPHOS, ET Pathway: F, N, S, NS, ROX HRR: Oxygraph-2k