Stearoyl-coenzyme A (CoA) desaturase (SCD) is a key enzyme involved in the
conversion of saturated fatty acids into monounsaturated fatty acids. Previ
ously, two members of this gene family namely, Scdl and Scd2, have been rep
orted. Here we report the identification and characterization of a novel me
mber of this family, Scd3, whose expression is restricted to mouse skin, sp
ecifically to the sebaceous gland. The Scd2 gene codes for a transcript of
similar to4.9 kb with an open reading frame that results in a 359-amino-aci
d protein, Scd3 shares 91 and 88% identity in the protein-coding region wit
h Scdl and Scd2, respectively, and maps to mouse chromosome 19 in very clos
e proximity to Scd1 and Scd2. Unlike Scd1, Scd3 expression is higher in mal
e mouse skin than in female mouse skin. The promoter sequence of Scd3 revea
ls similarity with Scdl in the proximal region but also possesses several d
istinctive features including the polyunsaturated fatty acid-response eleme
nt. Scd3 is expressed in the skin of young asebia mutant mice (SCd1(ab2J)/
Scd1(ab2J)) in the absence of Scd1. Scd3 expression changes during the mous
e hair cycle but not as dramatically as Scd1. The tissue-specific and sex-d
ependent expression of Scd3 suggests the presence of gene- and hormonal-spe
cific control mechanisms. (C) 2001 Academic Press.