• Home
  • Search Results
  • Overexpression of sphingosine kinase 1 in liver reduces triglyceride content in mice fed a low but not high-fat diet.

Overexpression of sphingosine kinase 1 in liver reduces triglyceride content in mice fed a low but not high-fat diet.

Biochimica et biophysica acta (2014-12-10)
Greg M Kowalski, Joachim Kloehn, Micah L Burch, Ahrathy Selathurai, Steven Hamley, Stéphanie A M Bayol, Séverine Lamon, Matthew J Watt, Robert S Lee-Young, Malcolm J McConville, Clinton R Bruce
ABSTRACT

Hepatic insulin resistance is a major risk factor for the development of type 2 diabetes and is associated with the accumulation of lipids, including diacylglycerol (DAG), triacylglycerols (TAG) and ceramide. There is evidence that enzymes involved in ceramide or sphingolipid metabolism may have a role in regulating concentrations of glycerolipids such as DAG and TAG. Here we have investigated the role of sphingosine kinase (SphK) in regulating hepatic lipid levels. We show that mice on a high-fat high-sucrose diet (HFHS) displayed glucose intolerance, elevated liver TAG and DAG, and a reduction in total hepatic SphK activity. Reduced SphK activity correlated with downregulation of SphK1, but not SphK2 expression, and was not associated with altered ceramide levels. The role of SphK1 was further investigated by overexpressing this isoform in the liver of mice in vivo. On a low-fat diet (LFD) mice overexpressing liver SphK1, displayed reduced hepatic TAG synthesis and total TAG levels, but with no change to DAG or ceramide. These mice also exhibited no change in gluconeogenesis, glycogenolysis or glucose tolerance. Similarly, overexpression of SphK1 had no effect on the pattern of endogenous glucose production determined during a glucose tolerance test. Under HFHS conditions, normalization of liver SphK activity to levels observed in LFD controls did not alter hepatic TAG concentrations. Furthermore, DAG, ceramide and glucose tolerance were also unaffected. In conclusion, our data suggest that SphK1 plays an important role in regulating TAG metabolism under LFD conditions.

MATERIALS
Product Number
Brand
Product Description

USP
Acetone, United States Pharmacopeia (USP) Reference Standard
Supelco
Acetone, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Sodium chloride, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Acetone, suitable for HPLC, ≥99.8%
Sigma-Aldrich
Acetone, suitable for HPLC, ≥99.9%
Sigma-Aldrich
Acetone, histological grade, ≥99.5%
Sigma-Aldrich
Acetone, HPLC Plus, for HPLC, GC, and residue analysis, ≥99.9%
Supelco
Chlorotrimethylsilane, for GC derivatization, LiChropur, ≥99.0% (GC)
Sigma-Aldrich
Acetone, ACS reagent, ≥99.5%
Sigma-Aldrich
Acetone, puriss., meets analytical specification of Ph. Eur., BP, NF, ≥99% (GC)
Sigma-Aldrich
Acetone, ACS reagent, ≥99.5%
Sigma-Aldrich
Acetone, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99.5% (GC)
Sigma-Aldrich
Acetone, Laboratory Reagent, ≥99.5%
Sigma-Aldrich
Sodium chloride solution, 5 M
Sigma-Aldrich
Sodium chloride solution, 5 M in H2O, BioReagent, for molecular biology, suitable for cell culture
Sigma-Aldrich
Sodium chloride, BioUltra, for molecular biology, ≥99.5% (AT)
Supelco
Acetone, analytical standard
Sigma-Aldrich
Chlorotrimethylsilane, produced by Wacker Chemie AG, Burghausen, Germany, ≥99.0% (GC)
Sigma-Aldrich
Sodium chloride, tested according to Ph. Eur.
Sigma-Aldrich
Chlorotrimethylsilane, ≥98.0% (GC)
Sigma-Aldrich
Chlorotrimethylsilane, puriss., ≥99.0% (GC)
Supelco
Sodium chloride, certified reference material for titrimetry, certified by BAM, ≥99.5%
Supelco
N,O-Bis(trimethylsilyl)trifluoroacetamide with trimethylchlorosilane, for GC derivatization, LiChropur, contains 1% TMCS, 99% (excluding TMCS)
Sigma-Aldrich
Sodium chloride, meets analytical specification of Ph. Eur., BP, USP, 99.0-100.5%
Supelco
N,O-Bis(trimethylsilyl)trifluoroacetamide with trimethylchlorosilane, with 1% trimethylchlorosilane, for GC derivatization, LiChropur
Sigma-Aldrich
Sodium chloride, BioXtra, ≥99.5% (AT)
Sigma-Aldrich
Sodium chloride solution, 0.9% in water, BioXtra, suitable for cell culture
Sigma-Aldrich
Bicinchoninic acid disodium salt hydrate, ≥98% (HPLC)
Sigma-Aldrich
Sodium chloride, for molecular biology, DNase, RNase, and protease, none detected, ≥99% (titration)
Sigma-Aldrich
Sodium chloride, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99%