ISOBUTYRAMIDE ACTIVATES TRANSCRIPTION OF HUMAN FETAL γ- AND MURINE EMBRYONIC εy-GLOBIN GENES
摘要
Objective. To examine the effect of isobutyramide synthesized in our laboratory on human and murine globingene expression and to test cell toxicity of the drug.Methods. ME L cells were transfected with the recombinant construct μLCRAγψβδβ3 and the stable transfor-mants were cultured in the medium with different concentrations of isobutyramide. The experimental mice and rab-bit were injected with different doses of isobutyramide. The globin mRNAs were analyzed by RNase protection as-say. The hematologdcal toxicity and electrolyte toxicity of the drug were tested.Results. An inducible and dose-dependent expression of the human γγ-, ββ- and mouse Aa-globin gene was ob-served in the transfected MEL cells. The induction of the human γ-globin gene is significant stronger than that ofthe ββ-globin gene. With 2.5 ～ 5 mmol/L isobutyramide, the induction of the human γ-globin gene is even moreeffective than that of mouse aa-globin gene. After a 15-day injection under the doses of 500 ～ 900mg * kg- 1 * d-1,the level of the mouse embryonic ey-globin mRNA could be significantly induced up to 3 ～ 4 fold of that of uninject-ed controls. The changes of hemoglobin(Hb), RBC, hematocrit(HCT), WBC, derived from mice injected withdifferent doses of isobutyramide at the interval of 24 hours for 2 ～4 weeks, were generally within the normalrange. In rabbits injected with isobutyramide in the same regiment for 2 weeks, the concentration of blood K+,Na +, C1- and CO.2 were all within normal range and serum ionic osmotic pressure remained stable as well.Conclusion. Our results suggested that isobutyramide is a weak inducer of cell differentiation, but it canselectively activate transcription of human γy-globin gene at a certain degree, and it can act on early stages of ery-throid progenitor differentiation in adult mice and activate transcription of embryonic ey-globin gene and have nohematological toxicity. Our results have further proved the potential value of isobutyramide in treatment ofβ