Study of aminoacidic sequences of vitamin D binding proteins involved in macrophage activation
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1
University of Florence, Department of Experimental Biomedical and Clinical Sciences, Italy
Vitamin D binding protein-derived macrophage activating factor (DBP-MAF) is a powerful activator of macrophages. Polymorphisms of the gene coding for vitamin D receptor (VDR) were associated with differential responses to DBP-MAF in human monocytes. Here we examined the relationships between these vitamin D binding proteins, i.e. DBP-MAF and VDR. VDR and two isoforms of DBP share 20% identity of aminoacid (aa) sequence in the tract coded for by exons 1, 2, 3 ,4, 5, i.e. aa 1-197. An higher degree of identity (40%) was observed in the tract coded for by exons 6, 7, 8, i.e. aa 217-330. The aa in position 445 was of particular interest; VDR and isoforms 1 and 3 of the DBP show a histidine in this position, whereas the isoform 2 shows an arginine. The observation that the VDR and isoforms 1 and 3 of the DBP have the same aa, at variance with the isoform 2, suggests that this variation is implicated in the evolutionary divergence in the genes coding for these vitamin D binding proteins. In fact, isoform 2 has a lysine in position 420 at variance with isoforms 1 and 3 that have a threonine that in turn is glycosylated so that DBP-MAF can be produced from isoforms 1 and 3 but not from isoform 2. These results are consistent with the concept that all the component of the vitamin D axis, i.e. vitamin D, DBP, DBP-MAF, and VDR participate in the regulation of the immune system through macrophage activation.
Acknowledgements
Marco Ruggiero, Stefania Pacini and Massimo Gulisano received grants from the University of Firenze and the Project PRIN 2009.
Keywords:
Vitamin D,
vitamin D receptor,
Evolution, Molecular,
Macrophages,
Sequence Homology, Amino Acid
Conference:
15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013.
Presentation Type:
Abstract
Topic:
Immune receptors and signaling
Citation:
Fiore
MG,
Magherini
S,
Gulisano
M,
Pacini
S and
Ruggiero
M
(2013). Study of aminoacidic sequences of vitamin D binding proteins involved in macrophage activation.
Front. Immunol.
Conference Abstract:
15th International Congress of Immunology (ICI).
doi: 10.3389/conf.fimmu.2013.02.01124
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Received:
15 Jul 2013;
Published Online:
22 Aug 2013.
*
Correspondence:
Dr. Maria G Fiore, University of Florence, Department of Experimental Biomedical and Clinical Sciences, Florence, Italy, mariagiulia.fiore@unifi.it