Third promoter and differential regulation of mouse and human fatty acid translocase/CD36 genes.

Fatty acid translocase (FAT)/CD36 is a multi-functional membrane protein participating in uptake of long-chain fatty acids and oxidized low density lipoprotein, playing an important role in lipid homeostasis. We reported the dual promoter structures of the mouse and human FAT/CD36 genes in relation to the tissue-specific expression and regulation by peroxisome proliferator-activated receptors (PPARs) (Sato et.al. J. Biol. Chem. 277, 15703-15711, 2002). However, these structures alone could not explain a large induction of the mRNA by a PPAR ligand in the mouse intestine. To learn more about the tissue-specific transcriptional regulation of the FAT/CD36 gene for lipid homeostasis at the whole body level, we cloned the cDNA for the induced mRNA in the mouse intestine and identified third promoter close to the first common exon of the gene. The human gene also has essentially the same gene organization. RT-PCR and Northern blot analyses showed that the three promoters are differentially used in various mouse tissues and the cultured human cells. The physiological significance of these complex promoter structures was suggested by the differential responsiveness to a peroxisome proliferator-activated receptor ligand and the differences in translational efficiencies or stabilities of the mRNA among the isoforms.