Evolution of the acute phase response: iron release by echinoderm (Asterias forbesi) coelomocytes, and cloning of an echinoderm ferritin molecule.
That the plasma concentration of certain divalent cations change during an inflammatory insult provides a major host defense response in vertebrate animals. This study was designed to investigate the involvement of iron sequestration in invertebrate immune responses. A ferritin molecule was cloned from an echinoderm coelomocyte cDNA library. The amino acid sequence showed sequence homology with vertebrate ferritin. The cDNA contained a conserved iron responsive element sequence. Studies showed that stimulated coelomocytes released iron into in vitro culture supernatants. The amount of iron in the supernatants decreased over time when the amebocytes were stimulated with LPS or PMA. Coelomocytes increased expression of ferritin mRNA after stimulation. In vertebrates, cytokines can cause changes in iron levels in macrophages. Similarly, echinoderm macrokines produced decreases in iron levels in coelomocyte supernatant fluids. These results suggest that echinoderm ferritin is an acute phase protein and suggest that sequestration of iron is an ancient host defense response in animals.
Beck
Gregory
G
Department of Biology, University of Massachusets at Boston, 100 Morrissey Blvd, ., Boston, MA 02125-3393, USA. greg.beck@umb.edu
Ellis
Thomas W
TW
Habicht
Gail S
GS
Schluter
Samuel F
SF
Marchalonis
John J
JJ
D000210:Acute-Phase Reaction; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D004447:Echinodermata / Q000145:classification / Q000235:genetics / Q000276:immunology*; D005293:Ferritins / Q000235:genetics*; D015723:Gene Library; D007375:Interleukin-1 / Q000494:pharmacology; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D010586:Phagocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D007375:Interleukin-1; D005293:Ferritins; D007501:Iron