TY - JOUR
T1 - Expression cloning of an oxysterol 7α-hydroxylase selective for 24- hydroxycholesterol
AU - Li-Hawkins, Jia
AU - Lund, Erik G.
AU - Bronson, Amy D.
AU - Russell, David W.
PY - 2000/6/2
Y1 - 2000/6/2
N2 - The synthesis of 7α-hydroxylated bile acids from oxysterols requires an oxysterol 7α-hydroxylase encoded by the Cyp7b1 locus. As expected, mice deficient in this enzyme have elevated plasma and tissue levels of 25- and 27-hydroxycholesterol; however, levels of another major oxysterol, 24- hydroxycholesterol, are not increased in these mice, suggesting the presence of another oxysterol 7α-hydroxylase. Here, we describe the cloning and characterization of murine and human cDNAs and genes that encode a second oxysterol 7α-hydroxylase. The genes contain 12 exons and are located on chromosome 6 in the human (CYP39A1 locus) and in a syntenic position on chromosome 17 in the mouse (Cyp39a1 locus). CYP39A1 is a microsomal cytochrome P450 enzyme that has preference for 24-hydroxycholesterol and is expressed in the liver. The levels of hepatic CYP39A1 mRNA do not change in response to dietary cholesterol, bile acids, or a bile acid-binding resin, unlike those encoding other sterol 7α-hydroxylases. Hepatic CYP39A1 expression is sexually dimorphic (female > male), which is opposite that of CYP7B1 (male > female). We conclude that oxysterol 7α-hydroxylases with different substrate specificities exist in mice and humans and that sexually dimorphic expression patterns of these enzymes in the mouse may underlie differences in bile acid metabolism between the sexes.
AB - The synthesis of 7α-hydroxylated bile acids from oxysterols requires an oxysterol 7α-hydroxylase encoded by the Cyp7b1 locus. As expected, mice deficient in this enzyme have elevated plasma and tissue levels of 25- and 27-hydroxycholesterol; however, levels of another major oxysterol, 24- hydroxycholesterol, are not increased in these mice, suggesting the presence of another oxysterol 7α-hydroxylase. Here, we describe the cloning and characterization of murine and human cDNAs and genes that encode a second oxysterol 7α-hydroxylase. The genes contain 12 exons and are located on chromosome 6 in the human (CYP39A1 locus) and in a syntenic position on chromosome 17 in the mouse (Cyp39a1 locus). CYP39A1 is a microsomal cytochrome P450 enzyme that has preference for 24-hydroxycholesterol and is expressed in the liver. The levels of hepatic CYP39A1 mRNA do not change in response to dietary cholesterol, bile acids, or a bile acid-binding resin, unlike those encoding other sterol 7α-hydroxylases. Hepatic CYP39A1 expression is sexually dimorphic (female > male), which is opposite that of CYP7B1 (male > female). We conclude that oxysterol 7α-hydroxylases with different substrate specificities exist in mice and humans and that sexually dimorphic expression patterns of these enzymes in the mouse may underlie differences in bile acid metabolism between the sexes.
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U2 - 10.1074/jbc.M001810200
DO - 10.1074/jbc.M001810200
M3 - Article
C2 - 10748047
AN - SCOPUS:0034595650
SN - 0021-9258
VL - 275
SP - 16543
EP - 16549
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 22
ER -