TfR mRNA expression in erythroid and nonerythroid cells.
RNA samples from erythroid (SCF progenitors, c-Kit overexpressing erythroblasts, v-Ski progenitors, and HD3E22 cells) and nonerythroid cell types (MC29-HD11 macrophages, CEF, and LMH cells) were subjected to Northern blot analysis. Erythroid cell types were cultured in the presence of 1 mg/mL Tf (+Tf), HD3E22 erythroblasts (additionally for direct comparison), and the nonerythroid cells under standard conditions (without extra iron source). Northern blots were sequentially hybridized with a 32P-labeled probe specific for chicken TfR, and for normalization with 18S rRNA. The signals of the PhosphoImages were quantified by using ImageQuant software (Molecular Dynamics) and are expressed in relative units (ru; maximum value for each cell type set to 100). To facilitate comparison, the results of TfR protein expression measurements on the cell surface are indicated on top of the diagram. Abbreviations are the same as those in Figure 1.
