Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/1997
Publication Date: N/A
Interpretive Summary: This research was focused on the isolation of the gene that encodes the swine apolipoprotein E (apo-E). Apo-E has several functions including the transport and metabolism of cholesterol and triglycerides. In humans, there are naturally occurring variants of apo-E, and some of them have been found to be associated with problems like type III hyperlipoproteinemia and atherosclerosis. Pigs are excellent models for studying problems like these because they have similar cardiovascular and gastrointestinal physiology to that of humans. Therefore, the goal of this work was to characterize the gene that encodes apo-E in pigs. In order to investigate this, a pig genomic library was searched with DNA from the mouse apo-E gene to locate the DNA for the swine apo-E gene. A clone containing the DNA for the pig apo-E gene was found and characterized with respect to its naturally occurring arrangement in the pig genome. The swine apo-E protein was also analyzed and compared to the same protein found in other species to search for differences and similarities from one species to the next. A repetitive sequence of DNA called a microsatellite was found in the pig apo-E gene and used to map the position of the apo-E gene within a large pig reference family. This linkage mapping was used with fluorescent mapping techniques to localize this gene to the middle region (called q2.1) of swine chromosome 6.
Technical Abstract: This report describes the isolation and genetic characterization of the porcine apolipoprotein E gene. A single positive recombinant phage clone containing a 10.7 Kb insert was isolated from a porcine genomic library and a 4.2 Kb fragment subcloned and sequenced. The fragment contained the entire apo-E gene in addition to upstream and downstream sequences (GenBank accession number 470240). The porcine apo-E gene is made up of four exons and three introns and encodes for a a preapo-E protein comprised of a signal peptide of 18 amino acids and a mature protein of 299 amino acids. The apo-E gene contains a (CG)13 microsatellite marker within intron three which is unique to the pig. This microsatellite is moderately polymorphic and at least four alleles were evident at this locus among 10 individuals per breed from Yorkshire, Hampshire, Landrace and Duroc animals. Finally, localization of the porcine apo-E gene to chromosome 6 band q2.1 was determined by fluorescent in situ hybridization and confirmed by genetic linkage analysis.