AA amyloidosis-resistant CE/J mice have Saa1 and Saa2 genes that encode an identical SAA isoform. (March 2014)

• Record Type: Journal Article
• Authors: Mori, Masayuki; Tiang, Geng; Higuchi, Keiichi
• Is Part Of: Amyloid. Volume 21:Number 1(2014:Mar.)
• Page Start: 1
• Page End: 8
• Publication Date: 2014-03
• Subjects: Amyloidosis -- Periodicals; 616.3995
• DOI: 10.3109/13506129.2013.852529
• Languages: English
• ISSNs: 1350-6129

Abstract

<abstract> <title>Abstract</title> <p>The CE/J mouse strain is resistant to amyloid A protein (AA) amyloidosis. In contrast to AA amyloidosis-susceptible mouse strains that concomitantly express serum amyloid A precursor protein (SAA) types 1 and 2 isoforms encoded by the <italic>Saa1</italic> and <italic>Saa2</italic> genes, respectively, in response to inflammatory stimulation from the liver, CE/J mice express only a single SAA isoform named SAA2.2. In addition, CE/J mice uniquely possess a Q30L amino acid substitution in SAA2.2 that inhibits amyloidogenesis. To elucidate the genetic basis underlying the expression of only a single SAA isoform in this strain, we conducted PCR cloning and nucleotide sequencing of the <italic>Saa1</italic> and <italic>Saa2</italic> genes from the CE/J genome. We revealed that CE/J mice possess functional <italic>Saa1</italic> and <italic>Saa2</italic> genes. Intriguingly, the two genes were identical with respect to amino acid sequence, each encoding the SAA2.2 isoform. RT-PCR analysis of inflamed liver tissue from CE/J mice demonstrated that both genes are expressed at equivalent levels. Reporter assays revealed that promoter/enhancer sequences of <italic>Saa1</italic> and <italic>Saa2</italic> genes in CE/J are also functional. These results indicate that the SAA2.2 isoform in CE/J is a mixture of <italic>Saa1</italic> and <italic>Saa2</italic> gene products.</p> </abstract>