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

Highlights: • The full length rat SAA4 (rSAA4) mRNA was characterized by rapid amplification of cDNA ends. • rSAA4 mRNA has 1830 bases including a GA dinucleotide tandem repeat in the 5′UTR. • Three consecutive C/EBP promoter elements are crucial for transcription of rSAA4. • rSAA4 is abundantly expressed in the liver on mRNA and protein level. - 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 inmore » 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.« less
Authors:
 [1] ; ;  [2] ; ; ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ; ; ;  [1] ;  [1]
  1. Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz (Austria)
  2. Institute of Human Genetics, Medical University of Graz, Graz (Austria)
  3. Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz (Austria)
  4. Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz (Austria)
  5. (Austria)
  6. Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN (United States)
Publication Date:
OSTI Identifier:
22416702
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 450; Journal Issue: 4; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; FLUORESCENCE; GENES; HEPATOMAS; HUMAN POPULATIONS; INFLAMMATION; LIVER; LUCIFERASE; MESSENGER-RNA; MICE; MICROSCOPY; PROMOTERS; RATS; TRANSCRIPTION; VARIATIONS