Cell lines

HepG2

Preparation Method

Tracing the oxidation of 13C16 palmitic acid in HepG2 cells to examine the effect of VB treatment on cellular mitochondrial fatty acid oxidation.

Reaction Conditions

10,50 ?M for 12h

Applications

Delta-Valerobetaine decreased the formation of labeled acetyl-CoA by approximately 75% compared to vehicle . Addition of carnitine back to cells pretreated with delta-Valerobetaine for 12 hours restored the carnitine-dependent formation of mitochondrial acetyl-CoA . Co-treatment of delta-Valerobetaine with the addition of stable isotope-labeled palmitate decreased the formation of labeled acetyl-CoA by approximately 25% compared to vehicle.

Animal models

germ-free (GF) mice

Preparation Method

Delta-Valerobetaine is not present in the sterilized chow (Teklad) used as the control diet for GF and conventionalization experiments. The conventional chow (Labdiet), which was not autoclavable, was used as the control for conventional mouse experiments.

Dosage form

10,25,50,100 mg/kg 6 weeks

Applications

Delta-Valerobetaine alters carnitine shuttle metabolism in male and female mice. VB decreases circulating carnitines in mice. Delta-Valerobetaine decreases circulating and hepatic beta-hydroxybutyrate, produced from mitochondrial fatty acid oxidation during fasting. VB alters neutral lipid profiles liver, heart, and brain of male and female mice. Neutral lipids from untargeted lipidomic profiling with average fold-change greater than 2 in 100 mg/kg Delta-Valerobetaine -treated mice (n = 5 male, n = 5 female) versus control (n = 5 male, n = 5 female).

Delta-Valerobetaine is a precursor of trimethylamine N-oxide (TMAO)^[1]. Delta-Valerobetaine, microbiome-derived metabolite, is a diet-dependent obesogen that is increased with phenotypic obesity and is correlated with visceral adipose tissue mass in humans^[2].

Delta-Valerobetaine is absent in germ-free mice and their mitochondria but present in ex-germ-free conventionalized mice and their mitochondria. Mechanistic studies in vivo and in vitro show Delta-Valerobetaine is produced by diverse bacterial species and inhibits mitochondrial fatty acid oxidation through decreasing cellular carnitine and mitochondrial long-chain acyl-coenzyme As. delta-Valerobetaine administration to germ-free and conventional mice increases visceral fat mass and exacerbates hepatic steatosis with a western diet but not control diet. Delta-Valerobetaine provides a molecular target to understand and potentially manage microbiome-host symbiosis or dysbiosis in diet-dependent obesity. Delta-Valerobetaine is produced in the rumen from free TML that occurs ubiquitously in vegetable kingdom^[3].

Delta-Valerobetaine appears to be degraded by gut microbiota, as it happens for γ-butyrobetaine. In the biochemical pathways for the production and metabolism of TMA and TMAO, compounds containing the trimethylammonium group, such as betaines, choline, carnitine, are metabolized by gut microbiota producing TMA which is absorbed and travels via the portal circulation to the liver, where it is oxidized by flavin monooxygenases (FMO1 and FMO3) to TMAO, a metabolite known to positively correlate to the occurrence of cardiovascular risks^[4-7].

References:
[1]. Servillo L, et al. Ruminant meat and milk contain δ-valerobetaine, another precursor of trimethylamine N-oxide (TMAO) like γ-butyrobetaine. Food Chem. 2018 Sep 15;260:193-199
[2]. Liu K H, Owens J A, Saeedi B, et al. Microbial metabolite delta-valerobetaine is a diet-dependent obesogen[J]. Nature Metabolism, 2021, 3(12): 1694-1705.
[3]. Servillo L, Giovane A, Cautela D, et al. Where does Nε-trimethyllysine for the carnitine biosynthesis in mammals come from?[J]. PloS one, 2014, 9(1): e84589.
[4]. Wang Z, Klipfell E, Bennett B J, et al. Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease[J]. Nature, 2011, 472(7341): 57-63.
[5].Zeisel S H, Warrier M. Trimethylamine N-oxide, the microbiome, and heart and kidney disease[J]. Annual review of nutrition, 2017, 37: 157-181.
[6]. Randrianarisoa E, Lehn-Stefan A, Wang X, et al. Relationship of serum trimethylamine N-oxide (TMAO) levels with early atherosclerosis in humans[J]. Scientific reports, 2016, 6(1): 1-9.
[7]. Subramaniam S, Fletcher C. Trimethylamine N(C)\oxide: breathe new life[J]. British Journal of Pharmacology, 2018, 175(8): 1344-1353.