Sphingolipids modulate many aspects of cell function, including the expression of cytochrome P450, a superfamily of heme proteins that participate in the oxidation of a wide range of compounds of both endogenous (steroid hormones and other lipids) and exogenous (e.g. alcohol, drugs and environmental pollutants) origin. Cytochrome P450-2C11 (CYP 2C11) is down-regulated in response to interleukin-1β (IL-1β), and this response involves the hydrolysis of sphingomyelin to ceramide as well as ceramide to sphingosine, and phosphorylation of sphingosine to sphingosine 1-phosphate. Activation of ceramidase(s) are a key determinant of which bioactive sphingolipid metabolites are formed in response to IL-1β. Ceramidase activation also appears to account for the loss of expression of CYP 2C11 when hepatocytes are placed in cell culture, and the restoration of expression when they are plated on Matrigel; hence, this pathway is influenced by, and may mediate, interactions between hepatocytes and the extracellular matrix. Recent studies using inhibitors of sphingolipid metabolism have discovered that sphingolipids are also required for the induction of CYP 1A1 by 3-methylcholanthrene, however, in this case, the requirement is for de novo sphingolipid biosynthesis rather than the turnover of complex sphingolipids. These findings illustrate how changes in sphingolipid metabolism can influence the regulation of at least severa1 isoforms of cytochrome P450. Copyright (C) 1999 Elsevier Science Ireland Ltd.
|Number of pages||9|
|Journal||Chemistry and Physics of Lipids|
|State||Published - Nov 1999|
Bibliographical noteFunding Information:
This work was supported by GM46368 and G12RR03062 (to A.H.M. and J. S.) and GM46897 (to E.T.M.). We thank Dr Ron Riley for the gift of ISP1.
- Cytochrome P450
- Xenobiotic metabolism
ASJC Scopus subject areas
- Molecular Biology
- Organic Chemistry
- Cell Biology