Liver X receptor alpha and beta genes have the potential role on loin lean and fat content in pigs

Liver X receptor alpha (LXRA) and beta (LXRB) are members of the nuclear receptor subfamily and are important regulators of genes involved in lipid, fatty acid and glucose metabolism in liver, and adipose tissue as well as in skeletal muscle. To investigate whether the two LXR genes play a role in influencing lean and fat growth in pigs, we discovered and examined two polymorphisms in LXRA (LXRA Bsl in exon 2, and LXRA HpyCH4 III in intron 8) and one polymorphism in LXRB (LXRB Aci I in exon 5) for genetic linkage and association analyses. Linkage analyses using a three-generation resource family of a cross between the Berkshire and Yorkshire (BY) pig breeds assigned LXRA to SSC2 and LXRB to SSC6. Association analyses were carried out among those polymorphisms and traits evaluated in the BY F(2) family and four pig commercial populations. These analyses indicated that the LXRA HpyCH4 III polymorphism was significantly associated with loin eye area and total lipid in individuals from the BY family. Significant associations were also found between Bsl I polymorphism in LXRA and boneless loin (%), as well as marbling score in one commercial line. The LXRB Aci I polymorphism was significantly associated with lean meat and fat content in the BY family and a number of the commercial lines examined. Our current findings suggested that LXRA and LXRB might have potential effects, especially for loin lean and fat content.