Metallothionein isogene transcription in red blood cell precursors from human cord blood

The in vitro transcription patterns for 10 functional metallothionein (MT) isogenes have been investigated in red blood cell (RBC) precursors from hum an cord blood. Active transcription status of the isogenes, MT-0, MT-1A, MT -1B, MT-IE, MT-1G, MT-1X, and MT-2A, was detected in both ex vivo expanded RBC precursors (burst-forming unit-erythroid) and glycophorin A(+) and CD71 (+) cells separated by magnetic cell sorting. Transcription patterns of the se isogenes were analyzed at different times of incubation with the additio n of Zn supplement. In neither the ex vivo expanded precursors nor glycopho rin A(+) and CD71(+) cells could MT-1F and MT-3 be detected. Transcripts of MT-4 were detected in glycophorin Ai and CD71(+) cells. Erythropoietin-res ponsive constitutive transcription of MT-1X and possible interleukin-3-resp onsive downregulation of MT-2A in ex vivo expanded precursors reveal their effect on MT biosynthesis. Biosynthesis and induction of MT at the protein level in the RBC precursors was also demonstrated by immunoblotting.