HMG BOX PROTEINS IN EARLY T-CELL DIFFERENTIATION

The central theme of this review is the molecular basis for commitment of cells to the T-cell lineage. Principles of transcriptional regulat ion are illustrated by two examples; the role of GATA-1 during erythro id differentiation and the function of MyoD-like proteins in myogenesi s. Several regulatory proteins have been described in the T-cell linea ge. Here, we focus attention on the HMG box family of DNA binding prot eins. This recently defined family can be divided in two subfamilies: the HMG/UBF and the TCF/SOX group. The first group contains at least t wo HMG boxes and binds DNA non-specifically, while the other group of proteins has one HMG box and interacts with DNA sequence-specifically. Characteristics of the most prominent members of both subfamilies wil l be discussed. In particular, we will address the role of HMG box pro teins in controlling the expression of T-cell specific proteins during differentiation.