Proc Natl Acad Sci U S A.
December 1, 1991;
Expression of GATA-binding proteins during embryonic development in Xenopus laevis.
Proteins that recognize the core sequence GATA are important regulators of hematopoietic-specific gene transcription. We have characterized cDNAs encoding the Xenopus laevis homologues of three related transcription factors, designated GATA-1
, -2, and -3. Comparative sequence analysis reveals strong conservation of the zinc-finger DNA-binding domain among all vertebrate GATA-binding proteins. GATA-2
polypeptides are homologous throughout their entire sequences, whereas GATA-1
sequence is conserved only in the region responsible for DNA binding. In Xenopus, RNAs encoding GATA-binding proteins are expressed in both larval and adult erythroid cells. GATA-1
, -2, and -3 RNAs are first detectable in early gastrula
(Nieuwkoop developmental stage 11
). This is earlier than the appearance of the early larval alpha T1 globin RNA (stage 15
), beta T1 globin RNA (stage 26
), or blood island
formation (stage 30). The expression of GATA-1
, -2, and -3 in early development may signal an early commitment of mesoderm
to form hematopoietic tissue
Proc Natl Acad Sci U S A.
GM42341 NIGMS NIH HHS
, HL02347 NHLBI NIH HHS
, HL32259 NHLBI NIH HHS
[+] show captions
FIG. 1. Comparison of the predicted amino acid sequences of vertebrate GATA-binding proteins. The zinc-finger DNA-binding domain is
underlined. The conserved amino acids outside the DNA-binding domain are marked (*). x, Xenopus; c, chicken; mn, mouse; h, human. (For
sequences, see refs. 14, 15, 18-23, and 46.)
FIG. 2. Distinctive features of the finger region of the vertebrate GATA-binding proteins. Amino acids 314-409 of the finger domains of
mGATA-1 are shown at the top with positions of divergence noted by X. Amino acid residues characteristic of the various GATA family members
are shown below. Intervening sequence position is marked based on the structure of the murine GATA-1 gene (30).
FIG. 3. Expression of GATA-binding protein genes in Xenopus
erythroid cells. Total cell RNAs (15 ,ug) were subjected to Northern
blot analysis and hybridized with a xGATA-1B cDNA probe (A) or
a xGATA-3 probe (B). Cells studied include Xenopus eggs or oocytes
(egg), tadpole erythroid cells, adult erythroid cells, adult reticulocytes
(retic), XTC cell line, XL cell line, murine erythroleukemia
cells (MEL), and human erythroleukemia cells (K562).
FIG. 4. Developmental expression of xGATA-binding protein
and larval globin genes. (A) Total cellular RNAs (1 /g) from staged
Xenopus embryos were subjected to RT-PCR using specific primers
for ,T1 globin, xGATA-1, xGATA-2, xGATA-3, and xMyoD. Controls
consisted of RT-PCR products from total RNA from Xenopus
adult erythroid cells and HeLa cells and H20. Lanes: 1, oocyte; 2,
4-cell embryo; 3, 32-cell embryo; 13, erythroid cells; 14, HeLa cells;
15, H20. The Nieuwkoop stage is indicated in the following lanes.
Lanes: 4, 7; 5, 9; 6, 11; 7, 12.5; 8, 13; 9, 18; 10, 24; 11, 26; 12, 30. (B)
Total cellular RNAs from staged Xenopus embryos were subjected
to Northern blot analysis and hybridized with an aT1 globin cDNA
probe (37). Nieuwkoop stages are as follows. Lanes: 1, 10.5; 2, 12;
3, 13; 4, 15; 5, 17; 6, 20; 7, 24; 8, 26; 9, 30; 10, 33; 11, 38; 12,