The transferrin receptor is the cell surface protein responsible for iron transport into mammalian cells. In this study the regulation of the transferrin receptor at the mRNA level will be studied. A myeloid cell line, HL-60, will be used as a model system. Transferrin receptor levels are known to be sensitive to differentiation, exogenous concentrations of non- transferrin iron and iron chelators. It has been hypothesized that receptor levels fluctuate during the cell cycle. A cDNA probe for the receptor will be used to measure the levels of mRNA. The size of the mRNA will be determined by Northern analysis. Transcriptional activity and the stability of mRNA will also be analyzed. These methods will be used to evaluate the level at which transferrin receptor mRNA is controlled when HL-60 cells are induced to differentiate along a monocytic pathway (with 12-0-tetradecanoyl phorbol-13-acetate) or along a granulocytic pathway (with dimethyl sulfoxide). The effects of externally added iron sources and iron chelators on the regulation of transferrin receptor mRNA levels and on the intracellular iron pools will also be measured, and the relationship between cell cycle phase and transferrin receptor mRNA levels and synthesis will be determined. This is a Research Opportunities for Women Career Advancement Award. This award will permit Dr. Enns to extend her studies of the control of cellular transferrin uptake to the level of receptor gene expression by enabling her to gain experience in techniques of molecular genetics.
