title: Characterization of rat serum amyloid A4 (SAA4): a novel member of the SAA superfamily.
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.
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Rossmann
authors.affiliation: Institute of Human Genetics, Medical University of Graz, Graz, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Windpassinger
authors.affiliation: Institute of Human Genetics, Medical University of Graz, Graz, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Brunner
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Alenka
authors.initials: A
authors.lastname: Kovacevic
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Natascha
authors.initials: N
authors.lastname: Schweighofer
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Malli
authors.affiliation: Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz, Austria.
authors.forename: Rufina
authors.initials: R
authors.lastname: Schuligoi
authors.affiliation: Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria; Institute of Biochemistry, Graz University of Technology, Graz, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Prokesch
authors.affiliation: Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Kluve-Beckerman
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Wolfgang F
authors.initials: WF
authors.lastname: Graier
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Kratky
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sattler
authors.affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria. Electronic address: ernst.malle@medunigraz.at.
authors.forename: Ernst
authors.initials: E
authors.lastname: Malle
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D008099:Liver / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D000685:Serum Amyloid A Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C000592765:SAA4 protein, rat; D000685:Serum Amyloid A Protein
keywords: Inflammation; Luciferase assay; Promoter activity; Rat SAA