Regulation of the tissue-specific expression of transferrin gene

Transferrin (Tf), the plasma protein involved in iron transport, seems to play complex physiological roles related to cell function, differentiation and proliferation. The protein is essentially synthesized in hepatocytes, but also in Sertoli cells, in the epithelial cells of the choroid plexus in rodents and in oligodendrocytes in all species analyzed. In this manuscript, we review the results obtained on Tf gene expression in the different cellular systems in which the protein is synthesized. In vitro and ex vivo experiments indicate that different combinations of transcription factors are necessary in different subsets of cells to achieve Tf tissue-specific expression. Several lines of transgenic mice were generated in which the expression of reporter genes is under the control of different Tf regulatory regions. More recently, transgenic mice were obtained using the complete human Tf gene and its 5' and 3' flanking sequences. These mice constitute the first model in which the physiological consequences of a specific Tf over expression in oligodendrocytes can be studied. Although much information is now available, further work is still necessary for a full understanding of the in vivo mechanisms responsible for the regulation of Tf gene expression.