Controlling α-globin: A review of α-globin expression and its impact on β-thalassemia

Synthesis of α-globin and α-globin subunits of hemoglobin occurs at high levels during erythrocyte differentiation in a tightly controlled and co-ordinated fashion. Expression of α-globin is a fascinatingly complex process which has been meticulously defined in several recent studies, from chromatin modifications to Pol II recruitment. Following this, α-globin transcripts are processed and stabilized by a protein complex which binds the 3′ untranslated region. Transcription and stabilization contribute to high level expression of α-globin. However, translation of α-globin at levels exceeding α-globin expression damages cellular membranes and results in β-thalassemia. It is, therefore, crucial that α-globin proteins are properly folded and stabilized, processes which are dependent on the presence of haem and AHSP. The exceedingly well-characterized process of α-globin expression elegantly illustrates the complex interaction of factors which are required to balance necessary high expression against the negative impacts of overexpression.