Sphingosine kinase activity and sphingosine-1 phosphate production in rat pancreatic islets and INS-1 cells: response to cytokines.

Abstract

Sphingosine-1 phosphate (S1P) is a bioactive sphingolipid with the potential to mobilize Ca2+, to inhibit apoptosis, and to promote mitogenesis. Sphingosine kinase (SPHK) and S1P were characterized in INS-1 insulinoma cells and isolated rat islets of Langerhans. SPHK activity increased in INS-1 cell homogenates treated with interleukin-1beta (IL-1beta) or tumor necrosis factor-alpha (TNF-alpha), and responses were additive. IL-1beta or TNF-alpha increased islet SPHK activity within 15 min to 1 h; activity remained elevated after 8 h. SPHK2 was the predominant active isoform in INS-1 cells; little or no SPHK1 activity was detected. Cytokines increased endogenous S1P biosynthesis in 32P(i)-prelabeled INS-1 cells, and cycloheximide inhibited the response after 8 h, suggesting that protein synthesis mediated the response. There was no [32P]S1P release from cells. Compared with basal values, IL-1beta and TNF-alpha induced increases in SPHK1a mRNA levels relative to 18S ribosomal RNA in INS-1 cells within 1 h; relative SPHK2 mRNA levels were unchanged after cytokine treatment. IL-1beta, but not TNF-alpha, induced relative SPHK1a mRNA expression levels within 1 h in islets, whereas SPHK2 mRNA levels were unchanged. Thus, IL-1beta and TNF-alpha induced an early and sustained increase in SPHK activity in INS-1 cells and isolated islets, suggesting that S1P plays a role in the pathological response of pancreatic beta-cells to cytokines.

• Authors: Lucy D Mastrandrea, Shawn M Sessanna, Suzanne G Laychock
• Journal: Diabetes (Diabetes) Vol. 54 Issue 5 Pg. 1429-36 (May 2005) ISSN: 0012-1797 [Print] United States
• PMID: 15855330 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cytokines
• DNA Primers
• Interleukin-1
• Lysophospholipids
• RNA, Messenger
• Tumor Necrosis Factor-alpha
• sphingosine 1-phosphate
• Phosphotransferases (Alcohol Group Acceptor)
• sphingosine kinase
• Sphingosine

Topics

• Animals
• Base Sequence
• Cell Line
• Cell Line, Tumor
• Cytokines (pharmacology)
• DNA Primers
• Interleukin-1 (pharmacology)
• Islets of Langerhans (drug effects, physiology)
• Kinetics
• Lysophospholipids (metabolism)
• Phosphotransferases (Alcohol Group Acceptor) (genetics, metabolism)
• RNA, Messenger (genetics)
• Rats
• Sphingosine (analogs & derivatives, metabolism)
• Substrate Specificity
• Tumor Necrosis Factor-alpha (pharmacology)