X-linked thrombocytopenia with thalassemia from a mutation in the amino finger of GATA-1 affecting DNA binding rather than FOG-1 interaction.
Transcription factor GATA-1 is essential for the development of erythroid cells and megakaryocytes. Each of its 2 zinc fingers is critical for normal function. The C-terminal finger is necessary for DNA binding. The N finger mediates interaction with FOG-1, a cofactor for GATA-1, and also modulates DNA-binding affinity, notably at complex or palindromic GATA sites. Residues of the N finger-mediating interaction with FOG-1 lie on the surface of the N finger facing away from DNA. Strong sequence conservation of residues facing DNA suggests that this other surface may also have an important role. We report here that a syndrome of X-linked thrombocytopenia with thalassemia in humans is caused by a missense mutation (Arg216Gln) in the GATA-1 N finger. To investigate the functional consequences of this substitution, we used site-directed mutagenesis to alter the corresponding residue in GATA-1. Compared with wild-type GATA-1, Arg216Gln GATA-1 shows comparable affinity to single GATA sites but decreased affinity to palindromic sites. Arg216Gln GATA-1 interacts with FOG-1 similarly with wild-type GATA-1. Arg216Gln GATA-1 supports erythroid maturation of GATA-1 erythroid cells, albeit at reduced efficiency compared with wild-type GATA-1. Together, these findings suggest that residues of the N finger of GATA-1-facing DNA contribute to GATA-1 function apart from interaction with the cofactor FOG-1. This is also the first example of beta-thalassemia in humans caused by a mutation in an erythroid transcription factor.
Division of Hematology/Oncology, Department of Medicine, Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
Channing
C
Yu
Kathy K
KK
Niakan
Mark
M
Matsushita
George
G
Stamatoyannopoulos
Stuart H
SH
Orkin
Wendy H
WH
Raskind
D019943:Amino Acid Substitution; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D050981:Erythroid-Specific DNA-Binding Factors; D004920:Erythropoiesis / Q000235:genetics; D005192:Family Health; D050982:GATA1 Transcription Factor; D008040:Genetic Linkage; D006801:Humans; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000378:metabolism*; D010375:Pedigree; D011485:Protein Binding / Q000235:genetics; D013577:Syndrome; D013789:Thalassemia / Q000150:complications / Q000235:genetics*; D013921:Thrombocytopenia / Q000150:complications / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014960:X Chromosome
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D009687:Nuclear Proteins; D014157:Transcription Factors; C498432:ZFPM1 protein, human; D004247:DNA