Goat liver X receptor α, molecular cloning, functional characterization and regulating fatty acid synthesis in epithelial cells of goat mammary glands.
The liver X receptor α (LXRα) is a nuclear receptor of the transcription factor and is known to play a crucial role in lipid metabolism processes such as bile acid and fatty acid synthesis in humans and rodents. However, very little information is available on the role of LXRα in the regulation of fatty acid synthesis in the goat mammary gland. In this investigation, a cDNA was isolated from the mammary gland of Xinong Saanen dairy goats and designated as goat LXRα. RT-PCR and RACE gave rise to the full-length cDNA of LXRα, which was comprised of 1654 bp and characterized by an ORF of 1344 bp and 5'- and 3'-UTR regions of 150 and 160 bp, respectively. The deduced amino acid sequence encodes 477 amino acids with a predicted molecular weight (MW) of 50.4kDa and a theoretical isoelectric point (pI) of 6.3. Additionally, homology search and sequence multi-alignment indicated that the putative goat LXRα amino acid sequence is very similar to those of cattle, mice, rats, swine, and humans. Bioinformatic predictions demonstrated that the LXRα protein is located in the nucleus, containing characteristic signatures of a nuclear receptor with DNA-binding domain (DBD) and ligand-binding domain (LBD). Real-time quantitative PCR suggested that LXRα was predominantly expressed in the small intestine, liver, spleen and mammary gland. Treatment of goat mammary gland epithelial cells (GMEC) with different concentrations (i.e., 0.01, 0.1, 1 μM) of T0901317, a synthetic agonist of LXRα, resulted in elevated sterol regulatory element binding protein 1 (SREBP1) and fatty acid synthase (FASN) mRNA levels in response to LXRα activation. The association between different T0901317 concentrations and fatty acid composition in GMEC also was examined using gas chromatography (GC). The results showed that activation of LXRα significantly increased GMEC C18:1 and C18:2 contents, but did not affect levels of saturated fatty acids (SFA). These discoveries are consistent with the notion that LXRα plays a key role in controlling lipogenesis and regulating synthesis of unsaturated fatty acids (UFA) in the mammary gland of goats, which may prove useful in regulation of milk fat production.
Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China. wangweixn007@nwsuaf.edu.cn
Wei
W
Wang
Jun
J
Luo
Yu
Y
Zhong
Xian-Zi
XZ
Lin
Heng-Bo
HB
Shi
Jiang-Jiang
JJ
Zhu
Jun
J
Li
Yu-Ting
YT
Sun
Wang-Sheng
WS
Zhao
D000818:Animals; D002417:Cattle; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D064429:Fatty Acid Synthases / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D006041:Goats / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007526:Isoelectric Point; D000071518:Liver X Receptors; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D016366:Open Reading Frames / Q000502:physiology; D009928:Organ Specificity / Q000502:physiology; D057093:Orphan Nuclear Receptors / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D020218:Response Elements / Q000502:physiology; D016415:Sequence Alignment; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D005227:Fatty Acids; D000071518:Liver X Receptors; C000605213:NR1H3 protein, human; C000605214:Nr1h3 protein, mouse; C000605215:Nr1h3 protein, rat; D057093:Orphan Nuclear Receptors; D051780:Sterol Regulatory Element Binding Protein 1; D064429:Fatty Acid Synthases