Characterization of rat serum amyloid A4 (SAA4): A novel member of the SAA superfamily

Christine Rossmann, Christian Windpassinger, Daniela Brunner, Alenka Kovacevic, Natascha Schweighofer, Roland Malli, Rufina Schuligoi, Andreas Prokesch, Barbara Kluve-Beckerman, Wolfgang F. Graier, Dagmar Kratky, Wolfgang Sattler, Ernst Malle*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The serum amyloid A (SAA) family of proteins is encoded by multiple genes, which display allelic variation and a high degree of homology in mammals. The SAA1/2 genes code for non-glycosylated acute-phase SAA1/2 proteins, that may increase up to 1000-fold during inflammation. The SAA4 gene, well characterized in humans (hSAA4) and mice (mSaa4) codes for a SAA4 protein that is glycosylated only in humans. We here report on a previously uncharacterized SAA4 gene (rSAA4) and its product in Rattus norvegicus, the only mammalian species known not to express acute-phase SAA. The exon/intron organization of rSAA4 is similar to that reported for hSAA4 and mSaa4. By performing 5′- and 3′RACE, we identified a 1830-bases containing rSAA4 mRNA (including a GA-dinucleotide tandem repeat). Highest rSAA4 mRNA expression was detected in rat liver. In McA-RH7777 rat hepatoma cells, rSAA4 transcription was significantly upregulated in response to LPS and IL-6 while IL-1α/β and TNFα were without effect. Luciferase assays with promoter-truncation constructs identified three proximal C/EBP-elements that mediate expression of rSAA4 in McA-RH7777 cells. In line with sequence prediction a 14-kDa non-glycosylated SAA4 protein is abundantly expressed in rat liver. Fluorescence microscopy revealed predominant localization of rSAA4-GFP-tagged fusion protein in the ER.

Original languageEnglish
Pages (from-to)1643-1649
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume450
Issue number4
DOIs
Publication statusPublished - 8 Aug 2014

Keywords

  • Inflammation
  • Luciferase assay
  • Promoter activity
  • Rat SAA

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fields of Expertise

  • Human- & Biotechnology

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)
  • Experimental

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