Fatty acid 2-hydroxylase regulates cAMP-induced cell cycle exit in D6P2T Schwannoma cells[S]

• Published in: Journal of lipid research Vol. 50; no. 6; pp. 1203 - 1208
• Main Authors: Alderson, Nathan L., Hama, Hiroko
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2009; American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: Animals; Bucladesine - pharmacology; Cell Cycle - drug effects; Cell Cycle - physiology; cell cycle control; Cell Line, Tumor; Ceramides - metabolism; cyclin-dependent kinase inhibitor; fatty acid α-hydroxylase; Fatty Acids - metabolism; Gene Silencing; hydroxy fatty acids; Mixed Function Oxygenases - antagonists & inhibitors; Mixed Function Oxygenases - genetics; Mixed Function Oxygenases - metabolism; Neurilemmoma - enzymology; Neurilemmoma - pathology; Rats; RNA, Small Interfering - genetics; sphingolipid; Sphingolipids - metabolism; Up-Regulation - drug effects; hydroxy fatty acids; fatty acid α-hydroxylase; cell cycle control; sphingolipid; cyclin-dependent kinase inhibitor
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M800666-JLR200

Sphingolipids are ubiquitous components of eukaryotic cells that regulate various cellular functions. In many cell types, a fraction of sphingolipids contain 2-hydroxy fatty acids, produced by fatty acid 2-hydroxylase (FA2H), as the N-acyl chain of ceramide [hydroxyl fatty acid (hFA)-sphingolipids]. FA2H is highly expressed in myelin-forming cells of the nervous system and in epidermal keratinocytes. While hFA-sphingolipids are thought to enhance the physical stability of specialized membranes produced by these cells, physiological significance of hFA-sphingolipids in many other cell types is unknown. In this study, we report novel roles for FA2H and hFA-sphingolipids in the regulation of the cell cycle. Treatment of D6P2T Schwannoma cells with dibutyryl-cAMP (db-cAMP) induced exit from the cell cycle with concomitant upregulation of FA2H. Partial silencing of FA2H in D6P2T cells resulted in 60–70% reduction of hFA-dihydroceramide and hFA-ceramide, with no effect on nonhydroxy dihydroceramide and ceramide. Under these conditions, db-cAMP no longer induced cell cycle exit, and cells continued to grow and divide. Immunoblot analyses revealed that FA2H silencing prevented db-cAMP-induced upregulation of cyclin-dependent kinase inhibitors p21 and p27. These results provide evidence that FA2H is a negative regulator of the cell cycle and facilitates db-cAMP-induced cell cycle exit in D6P2T cells.