Three functional ferritin genes have been identified so far in mammals, and they encode the cytosolic Heavy (FTH) and Light chain (FTL) and the mitochondrial ferritin. The expression of a transcript by a fourth ferritin-like gene (Ferritin-Heavy-Polypeptide-Like-17, FTHL17) on the X chromosome was reported in mouse spermatogonia and in early embryonic cells.METHODS:The intronless human FTHL17 gene encodes a protein with 64% identity to human FTH with substitution of key residues of the ferroxidase center. The gene was cloned into vectors for expression in Escherichia coli and mammalian cells, linked to a flag-tag.RESULTS:The recombinant FTHL17 from E. coli purified as an assembled 24-mer ferritin devoid of ferroxidase activity and with a reduced physical stability. When transiently expressed in mammalian cells the flag-FTHL17 assembled in ferritin shells that showed reduced stability to denaturants compared with flag H and L ferritins. Immunocytochemistry with anti-flag antibody decorated the nuclei of flag-FTHL17 transfected COS cells, but not those of the cells transfected with flag-FTH or flag-FTL.CONCLUSIONS:We concluded that FTHL17 encodes a ferritin-like protein without ferroxidase activity. Its restricted embryonic expression and partial nuclear localization suggest that this novel ferritin type may have functions other than iron storage.GENERAL SIGNIFICANCE:The work confirms the presence of a fourth functional human ferritin gene with properties distinct from the canonical cytosolic ones.

The Ferritin-Heavy-Polypeptide-Like-17 (FTHL17) gene encodes a ferritin with low stability and no ferroxidase activity and with a partial nuclear localization

REGONI, Maria;
2015-01-01

Abstract

Three functional ferritin genes have been identified so far in mammals, and they encode the cytosolic Heavy (FTH) and Light chain (FTL) and the mitochondrial ferritin. The expression of a transcript by a fourth ferritin-like gene (Ferritin-Heavy-Polypeptide-Like-17, FTHL17) on the X chromosome was reported in mouse spermatogonia and in early embryonic cells.METHODS:The intronless human FTHL17 gene encodes a protein with 64% identity to human FTH with substitution of key residues of the ferroxidase center. The gene was cloned into vectors for expression in Escherichia coli and mammalian cells, linked to a flag-tag.RESULTS:The recombinant FTHL17 from E. coli purified as an assembled 24-mer ferritin devoid of ferroxidase activity and with a reduced physical stability. When transiently expressed in mammalian cells the flag-FTHL17 assembled in ferritin shells that showed reduced stability to denaturants compared with flag H and L ferritins. Immunocytochemistry with anti-flag antibody decorated the nuclei of flag-FTHL17 transfected COS cells, but not those of the cells transfected with flag-FTH or flag-FTL.CONCLUSIONS:We concluded that FTHL17 encodes a ferritin-like protein without ferroxidase activity. Its restricted embryonic expression and partial nuclear localization suggest that this novel ferritin type may have functions other than iron storage.GENERAL SIGNIFICANCE:The work confirms the presence of a fourth functional human ferritin gene with properties distinct from the canonical cytosolic ones.
2015
Embryonic cell
Ferritin
Ferroxidase center
Protein stability
Amino Acid Sequence
Animals
Apoferritins
COS Cells
Cell Differentiation
Cell Nucleus
Cercopithecus aethiops
Embryonic Stem Cells
Escherichia coli
Gene Expression Regulation
Developmental
Hep G2 Cells
Humans
Mice
Molecular Sequence Data
Molecular Structure
Protein Denaturation
Protein Stability
Recombinant Proteins
Transfection
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11768/139356
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