Original Article

Chinese hamster ovary cells overexpressing the oxysterol binding protein (OSBP) display enhanced synthesis of sphingomyelin in response to 25-hydroxycholesterol

Correspondence to: Neale D. Ridgway

25-Hydroxycholesterol negatively regulates cholesterol synthesis and activates cholesterol esterification in a variety of cultured cells. Concurrent with these effects, 25-hydroxycholesterol also stimulates the synthesis of sphingomyelin in Chinese hamster ovary (CHO)-K1 cells. The role of oxysterol binding protein (OSBP), a high affinity receptor for 25-hydroxycholesterol, in activation of SM synthesis was assessed by overexpression in CHO-K1 cells. When compared to mock transfected controls, three CHO-K1 clones overexpressing OSBP by 10- to 15-fold displayed a 2- to 3-fold enhancement of [³H]serine incorporation into sphingomyelin when treated with 25-hydroxycholesterol. Closer examination of one of these clones (CHO-OSBP cells) revealed a >8.5-fold stimulation of sphingomyelin synthesis after a 6-h treatment with 25-hydroxycholesterol compared to 3.5-fold in controls, slightly higher basal levels of sphingomyelin synthesis, and a more rapid response to 25-hydroxycholesterol. [³H]serine incorporation into phosphatidylserine, phosphatidylethanolamine, ceramide, or glucosylceramide was affected by <15%. Synthesis of sphingomyelin from exogenous [³H]sphinganine-labeled ceramide was enhanced in overexpressing cells treated with 25-hydroxycholesterol. However, in vitro activities of sphinganine N-acyltransferase, sphingomyelin synthase, and serine palmitoyltransferase were not affected by OSBP overexpression or 25-hydroxycholesterol. Overexpression of OSBP or 25-hydroxycholesterol did not significantly affect the ceramide content of Golgi-enriched fractions from control or overexpressing cells. However, diglyceride mass was reduced in Golgi-enriched fractions from overexpressing cells and by treatment with 25-hydroxycholesterol.

Results from overexpressing cells show that OSBP potentiates the stimulatory effects of 25-hydroxycholesterol on sphingomyelin synthesis. 25-Hydroxycholesterol promotes translocation of OSBP to the Golgi apparatus where it appears to stimulate conversion of ceramide to sphingomyelin.—Lagace, T. A., D. M. Byers, H. W. Cook, and N. D. Ridgway. Chinese hamster ovary cells overexpressing the oxysterol binding protein (OSBP) display enhanced synthesis of sphingomyelin in response to 25-hydroxycholesterol. J. Lipid Res. 1999. 40: 109–116.

Supplementary key words: sphingomyelin, 25-hydroxycholesterol, oxysterol binding protein, ceramide

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				K. Bowden and N. D. Ridgway OSBP Negatively Regulates ABCA1 Protein Stability J. Biol. Chem., June 27, 2008; 283(26): 18210 - 18217. [Abstract] [Full Text] [PDF]

				G. D'Angelo, M. Vicinanza, A. Di Campli, and M. A. De Matteis The multiple roles of PtdIns(4)P - not just the precursor of PtdIns(4,5)P2 J. Cell Sci., June 15, 2008; 121(12): 1955 - 1963. [Abstract] [Full Text] [PDF]

				M. Kawano, K. Kumagai, M. Nishijima, and K. Hanada Efficient Trafficking of Ceramide from the Endoplasmic Reticulum to the Golgi Apparatus Requires a VAMP-associated Protein-interacting FFAT Motif of CERT J. Biol. Chem., October 6, 2006; 281(40): 30279 - 30288. [Abstract] [Full Text] [PDF]

				J. Dong, J. Liu, B. Lou, Z. Li, X. Ye, M. Wu, and X.-C. Jiang Adenovirus-mediated overexpression of sphingomyelin synthases 1 and 2 increases the atherogenic potential in mice J. Lipid Res., June 1, 2006; 47(6): 1307 - 1314. [Abstract] [Full Text] [PDF]

				R. J. Perry and N. D. Ridgway Oxysterol-binding Protein and Vesicle-associated Membrane Protein-associated Protein Are Required for Sterol-dependent Activation of the Ceramide Transport Protein Mol. Biol. Cell, June 1, 2006; 17(6): 2604 - 2616. [Abstract] [Full Text] [PDF]

				M. Johansson, M. Lehto, K. Tanhuanpaa, T. L. Cover, and V. M. Olkkonen The Oxysterol-binding Protein Homologue ORP1L Interacts with Rab7 and Alters Functional Properties of Late Endocytic Compartments Mol. Biol. Cell, December 1, 2005; 16(12): 5480 - 5492. [Abstract] [Full Text] [PDF]

				R. J. Perry and N. D. Ridgway The role of de novo ceramide synthesis in the mechanism of action of the tricyclic xanthate D609 J. Lipid Res., January 1, 2004; 45(1): 164 - 173. [Abstract] [Full Text] [PDF]

				J. Silva, A. Beckedorf, and E. Bieberich Osteoblast-derived Oxysterol Is a Migration-inducing Factor for Human Breast Cancer Cells J. Biol. Chem., July 3, 2003; 278(28): 25376 - 25385. [Abstract] [Full Text] [PDF]

				M. Johansson, V. Bocher, M. Lehto, G. Chinetti, E. Kuismanen, C. Ehnholm, B. Staels, and V. M. Olkkonen The Two Variants of Oxysterol Binding Protein-related Protein-1 Display Different Tissue Expression Patterns, Have Different Intracellular Localization, and Are Functionally Distinct Mol. Biol. Cell, March 1, 2003; 14(3): 903 - 915. [Abstract] [Full Text] [PDF]

				J. P. Wyles, C. R. McMaster, and N. D. Ridgway Vesicle-associated Membrane Protein-associated Protein-A (VAP-A) Interacts with the Oxysterol-binding Protein to Modify Export from the Endoplasmic Reticulum J. Biol. Chem., August 9, 2002; 277(33): 29908 - 29918. [Abstract] [Full Text] [PDF]

				S. Laitinen, M. Lehto, S. Lehtonen, K. Hyvarinen, S. Heino, E. Lehtonen, C. Ehnholm, E. Ikonen, and V. M. Olkkonen ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism J. Lipid Res., February 1, 2002; 43(2): 245 - 255. [Abstract] [Full Text] [PDF]

				M. Lehto, S. Laitinen, G. Chinetti, M. Johansson, C. Ehnholm, B. Staels, E. Ikonen, and V. M. Olkkonen The OSBP-related protein family in humans J. Lipid Res., August 1, 2001; 42(8): 1203 - 1213. [Abstract] [Full Text] [PDF]

				T. P. Levine and S. Munro Dual Targeting of Osh1p, a Yeast Homologue of Oxysterol-binding Protein, to both the Golgi and the Nucleus-Vacuole Junction Mol. Biol. Cell, June 1, 2001; 12(6): 1633 - 1644. [Abstract] [Full Text] [PDF]

				G. J. Schroepfer Jr. Oxysterols: Modulators of Cholesterol Metabolism and Other Processes Physiol Rev, January 1, 2000; 80(1): 361 - 554. [Abstract] [Full Text] [PDF]

				M. Medhora, M. Bousamra II, D. Zhu, L. Somberg, and E. R. Jacobs Upregulation of collagens detected by gene array in a model of flow-induced pulmonary vascular remodeling Am J Physiol Heart Circ Physiol, February 1, 2002; 282(2): H414 - H422. [Abstract] [Full Text] [PDF]