Biology subjects

Salt, I. P.

Publications and source records attributed to Salt, I. P..

2 recordsLinked to original sources

bioRxiv2022

Asymmetric dimethylarginine positively modulates Calcium-Sensing Receptor signalling to promote lipid accumulation and adiposity

Irreversible methylation of arginine residues generates asymmetric dimethylarginine (ADMA). ADMA is a competitive inhibitor of nitric oxide (NO) synthase and an independent risk factor for cardiovascular disease. Plasma ADMA concentrations increase with obesity and fall following weight loss. Here, we demonstrate that ADMA drives lipid accumulation through a newly identified NO-independent pathway via the amino-acid sensitive calcium-sensing receptor (CaSR). ADMA treatment of 3T3-L1 and HepG2 cells activates mTOR signalling and upregulates a suite of lipogenic genes with an associated increase in triglyceride content. Pharmacological blockade of CaSR inhibits ADMA driven lipid accumulation and ADMA treatment potentiates CaSR signalling via both Gq and Gi/o pathways. Impairment of ADMA metabolism in adipocytes in vivo, by dimethylamine dimethylaminohydrolase-1 (DDAH1) deletion, increases visceral adiposity and adipocyte hypertrophy. This study identifies a signalling mechanism for ADMA as an endogenous ligand of the G protein-coupled receptor CaSR that potentially contributes to the impact of ADMA in cardiometabolic disease.

physiology↗

bioRxiv2020

Microbiome-derived metabolites reproduce the mitochondrial dysfunction and decreased insulin sensitivity observed in type 2 diabetes

Diabetes is a global health problem that was estimated to be the 7th leading cause of death worldwide in 2016. Type 2 diabetes mellitus (T2DM) is classically associated with genetic and environmental factors, however recent studies have demonstrated that the gut microbiome, which is altered in T2DM patients, is also likely to play a significant role in disease development. Despite this, the identity of microbiome-derived metabolites that influence T2DM onset and/or progression remain elusive. Here we demonstrate that a serum biomarker for T2DM, previously of unknown structure and origin, is actually two microbiome-derived metabolites, 3-methyl-4-(trimethylammonio)butanoate (3M-4-TMAB) and 4-(trimethylammonio)pentanoate (4-TMAP). These metabolites are produced by the Lachnospiraceae family of bacteria, which are highly prevalent in the gut microbiome of T2DM patients and are associated with high dietary fat intake. Treatment of human liver cells with 3M-4-TMAB and 4-TMAP results in a distinct change in the acylcarnitine profile in these cells and significantly reduced their insulin sensitivity; both indicators of T2DM. These results provide evidence of a mechanistic link between gut microbiome derived metabolites and T2DM.

microbiology↗