Role of Helix-Loop-Helix Proteins during Differentiation of Erythroid Cells

Abstract

Helix-loop-helix (HLH) proteins play a profound role in the process of development and cellular differentiation. Among the HLH proteins expressed in differentiating erythroid cells are the ubiquitous proteins Myc, USF1, USF2, and TFII-I, as well as the hematopoiesis-specific transcription factor Tal1/SCL. All of these HLH proteins exhibit distinct functions during the differentiation of erythroid cells. For example, Myc stimulates the proliferation of erythroid progenitor cells, while the USF proteins and Tal1 regulate genes that specify the differentiated phenotype. This minireview summarizes the known activities of Myc, USF, TFII-I, and Tal11/SCL and discusses how they may function sequentially, cooperatively, or antagonistically in regulating expression programs during the differentiation of erythroid cells.

ACKNOWLEDGMENTS

We thank our colleagues in the Huang and Bungert laboratories for stimulating discussions.

This work was supported by grants from the NIH (J.B., RO1DK052356; J.B. and J.S., RO1DK083389; S.H., RO1HL090589 and RO1HL091929) and the American Heart Association (J.B.).