Journal
JOURNAL OF LIPID RESEARCH
Volume 50, Issue 4, Pages 602-610Publisher
ELSEVIER
DOI: 10.1194/jlr.M800206-JLR200
Keywords
sphingosine 1-phosphate; differentiation; adipose tissue
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Funding
- Nankai Ikuei Foundation ( to T. H., Kagawa, Japan)
- Mochida Memorial Foundation for Medical and Pharmaceutical Research
- Ministry of Education, Culture, Sports, Science and Technology of Japan [19790650, 17790151]
- Grants-in-Aid for Scientific Research [17790151, 19790650] Funding Source: KAKEN
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Sphingosine 1-phosphate (S1P) is a lysophospholipid mediator that exerts numerous biological activities both as a receptor ligand and as an intracellular second messenger. In the present study, we explored roles of sphingosine kinase (SphK), an S1P-producing enzyme, in adipose tissue. We utilized mouse 3T3-L1 cells as an in vitro model of adipogenesis, using a mixture of insulin/dexamethasone/3-isobutyl-1-methylxanthine (IBMX) to induce differentiation. Real-time quantitative PCR (qRT-PCR) assays revealed that the expression levels of transcripts encoding both isoforms of SphK-1 and SphK-2 are up-regulated during adipogenesis (37.6- and 6.6-fold vs. basal, P, 0.05, respectively). Concomitantly, SphK-1/SphK-2 protein abundance and S1P contents of these cells increased at 3 days after hormonal stimulation. Loss-of-function approaches by pharmacological inhibition of SphK activity as well as by transfection with small interfering RNA (siRNA) against SphK-1 led to significant attenuation of lipid droplet accumulation and adipocyte marker gene expression. We detected marked elevation of SphK-1 mRNA in adipose tissue derived from 13-week-old ob/ob mice with obese phenotype than their lean littermates. These results suggest that increased expression of SphK, an S1P-producing enzyme, plays a significant role during adipogenesis, potentially providing a novel point of control in adipose tissue. -Hashimoto, T., J. Igarashi, and H. Kosaka. Sphingosine kinase is induced in mouse 3T3-L1 cells and promotes adipogenesis. J. Lipid Res. 2009. 50: 602-610.
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