Transcript variant of the porcine liver X receptor alpha (LXRα) expressed in the thymus and spleen

The liver X receptor alpha (LXRα) is a ligand-inducible transcription factor that belongs to a member of the nuclear receptor superfamily. LXRα functions as a transcriptional regulator of several important genes involved in the metabolism of cholesterol, fatty acids, and glucose. We determined the nucleotide sequences of the porcine LXRα cDNA by using full-length cDNA clones derived from porcine cDNA libraries. Two porcine LXRα transcript variants that differed only in the 5'-untranslated region (5'-UTR) were identified, and designated as porcine LXRα-1 and LXRα-2. The length of the 5'-UTR of the porcine LXRα-1 is 183 bp, whereas that of LXRα-2 is 216 bp. Both transcripts have an identical 1344-bp putative protein-coding region that encodes 447 amino acids. The 38bp of 3'side of the 5'-UTR is identical between LXRα-1 and LXRα-2. The LXRα-1 is similar to the mRNA of porcine LXRα (DQ059138) . The 5'-UTR of LXRα-1 is 34bp longer than that of DQ059138. The 5'-UTR sequence of LXRa-1 and DQ059138 is similar to the sequence of the exonl of the human LXRα gene and the mouse LXRα gene. The 54bp of the upstream region of the 5'-UTR of LXRα-2 is similar to the exon6 of human ACP2 gene. By using RT-PCR, the expression of the porcine LXRα-1 transcript was detected in the liver, kidney, small intestine, heart, muscle, thymus, spleen, and brain, whereas the porcine LXRα-2 transcript was expressed in the thymus and spleen.