Induction of stearoyl CoA desaturase is associated with high-level induction of emerin RNA

The genes encoding enzymes involved in fatty acid metabolism are regulated by sterols. Stearoyl CoA desaturase, a key enzyme in the synthesis of unsat urated fatty acyl-CoAs is transcriptionally regulated by fat-free diet and sterols. To identify other genes that are induced in rat liver by fat-free diet we performed an in vivo gene expression profile analysis using DNA mic roarrays. Here we report; that among the genes highly expressed is emerin, an integral protein of the inner nuclear membrane. Mutated or nonexpressed emerin occurs in patients with muscular dystrophy. Sterol regulatory elemen t binding proteins activate the transcription of several sterol regulated g enes. To investigate whether sterol regulatory element binding proteins or indirectly cholesterol activates the transcription of stearoyl CoA desatura se and emerin, we cultured Chinese hamster ovary (CHO), either in cholester ol-rich or cholesterol-depleted mediums. We also transiently transfected th e cell culture with plasmid encoding sterol regulatory element binding prot eins in cholesterol-rich medium. Our data show that cholesterol-supplemente d media as well, as the transient transfection induced the expression of st earoyl CoA desaturase RNA 3.5- and 7-fold respectively. However, the RNA le vel of emerin was not altered under these conditions, implying that the par allel induction of emerin is independent of the sterol regulatory element b inding regulation pathway. (C) 2001 Academic Press.