Ferritin L and H subunits are differentially regulated on a post-transcriptional level.
Ferritin plays an important role in the storage and release of iron, an element utilized in cellular processes such as respiration, gene regulation, and DNA replication and repair. Ferritin in animals is composed of 24 ferritin L (FTL) and ferritin H (FTH) subunits in ratios that vary in different cell types. Because the subunits are not functionally interchangeable, both L and H units are critical for maintaining iron homeostasis and protecting against iron overload. FTL and FTH are regulated primarily at a post-transcriptional level in response to cellular iron concentrations. Individual regulation of FTL and FTH is of much interest, and although transcriptional differences between FTL and FTH have been shown, differences in their post-transcriptional regulation have not been evaluated. We report here that FTL and FTH are differentially regulated in 1% oxygen on a post-transcriptional level. We have designed a quantitative assay system sensitive enough to detect differences between FTL and FTH iron regulatory elements (IREs) that a standard electrophoretic mobility shift assay does not. The FTL IRE is the primary responder in the presence of an iron donor in hypoxic conditions, and this response is reflected in endogenous FTL protein levels. These results provide evidence that FTL and FTH subunits respond independently to cellular iron concentrations and underscore the importance of evaluating FTL and FTH IREs separately.
Sammarco
Mimi C
MC
Department of Genetics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Ditch
Scott
S
Banerjee
Ayan
A
Grabczyk
Ed
E
D001052:Apoferritins / Q000096:biosynthesis* / Q000235:genetics; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004261:DNA Replication / Q000187:drug effects / Q000502:physiology; D005293:Ferritins / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D019190:Iron Overload / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D020218:Response Elements / Q000502:physiology
C507433:FTL protein, human; D005293:Ferritins; D001052:Apoferritins; D007501:Iron; D010100:Oxygen