Transcriptional regulation of ferritin H and L subunits in adult erythroid and liver cells from the mouse. Unambiguous identification of mouse ferritin subunits and in vitro formation of the ferritin shells.
Ferritin H and L subunits present cell-specific features of structure, function, and transcriptional regulation. Mouse Friend erythroleukemia cells offer an interesting model to analyze the erythroid-specific expression of ferritin genes for comparison with the liver, an iron-storing tissue. cDNA clones for mouse ferritin H and L subunits have been isolated and sequenced. The two subunits have very similar calculated masses, 20.9 and 20.6 kDa for H and L, respectively. Electrophoretic analysis of the subunits encoded by the cDNA 1) allows unambiguous identification of mouse ferritin subunits; 2) clearly shows that mouse H and L chains can make heteropolymers in vitro; and 3) demonstrates that, at least in vitro, free subunits can coexist with subunits polymerized into complete shells. The mouse ferritin gene family displays a variable degree of complexity, ranging from three homologous sequences for the H genes to 10-14 homologous loci for the L genes. Transcription of ferritin genes exhibits tissue-specific difference. Nuclear transcriptional run-off experiments show that the L gene is more actively transcribed in the liver than in Friend erythroleukemia cells at different stages of maturation. The accumulation of the H subunit mRNA which results from dimethyl sulfoxide induction of Friend cells is the consequence of an increase in the transcription rate of the H gene. However, the H gene mRNA is transcribed at a similar rate in the liver and in induced Friend cells although 5-fold more mRNA accumulates in these cells. Therefore, there is a tissue-specific regulation of mouse ferritin expression at both the transcription and mRNA stability levels.
Beaumont
C
C
Laboratoire de Génétique Moléculaire, Faculté Xavier Bichat, Paris, France.
Dugast
I
I
Renaudie
F
F
Souroujon
M
M
Grandchamp
B
B
D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004920:Erythropoiesis; D005293:Ferritins / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics*; D008099:Liver / Q000502:physiology*; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D046911:Macromolecular Substances; D012333:RNA, Messenger; D004247:DNA; D005293:Ferritins