A 5' REGULATORY SEQUENCE CONTAINING 2 ETS MOTIFS CONTROLS THE EXPRESSION OF THE WISKOTT-ALDRICH-SYNDROME PROTEIN (WASP) GENE IN HUMAN HEMATOPOIETIC-CELLS

The recently-identified Wiskott-Aldrich syndrome protein gene (WASP) i s responsible fbr the Wiskott-Aldrich X-linked immunodeficiency as wel l as for isolated X-linked thrombocytopenia (XLT). To characterize the regulatory sequences of the WASP gene, we have isolated, sequenced an d functionally analyzed a 1.6-Kb DNA fragment upstream of the WASP cod ing sequence. Transfection experiments showed that this fragment is ca pable of directing efficient expression of the reporter chloramphenico l acetyltransferase (CAT) gene in all human hematopoietic cell lines t ested. Progressive 5' deletions showed that the minimal sequence requi red for hematopoietic-specific expression consists of 137 bp upstream of the transcription start site. This contains potential binding sites for several hematopoietic transcription factors and, in particular, t wo Ets-1 consensus that proved able to specifically bind to proteins p resent in nuclear extracts of Jurkat cells. Overexpression of Ets-1 in HeLa resulted in transactivation of the CAT reporter gene under the c ontrol of WASP regulatory sequences. Disruption of the Ets-binding seq uences by side-directed mutagenesis abolished CAT expression in Jurkat cells, indicating that transcription factors of the Ets family play a key role in the control of WASP transcription. (C) 1998 by The Americ an Society of Hematology.