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 unsaturated 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 microarrays. 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 element binding proteins activate the transcription of several sterol regulated genes. To investigate whether sterol regulatory element binding proteins or indirectly cholesterol activates the transcription of stearoyl CoA desaturase and emerin, we cultured Chinese hamster ovary (CHO), either in cholesterol-rich or cholesterol-depleted mediums. We also transiently transfected the cell culture with plasmid encoding sterol regulatory element binding proteins in cholesterol-rich medium. Our data show that cholesterol-supplemented media as well as the transient transfection induced the expression of stearoyl CoA desaturase RNA 3.5- and 7-fold respectively. However, the RNA level of emerin was not altered under these conditions, implying that the parallel induction of emerin is independent of the sterol regulatory element binding regulation pathway.