Arg216Gln GATA-1 allows erythroid maturation in G1E cells.

G1E cells, which lack GATA-1, undergo erythroid differentiation after retroviral infection with GATA-1.8 Stable introduction of estrogen-receptor fusion versions of GATA-1 (GATA-1/ER) allows this differentiation to be controlled by the addition of β-estradiol, which activates the GATA-1/ER fusion protein.19,29 (A) Wild-type and Arg216Gln versions of GATA-1/ER fusion proteins allow G1E cells to undergo erythroid differentiation, evidenced here by quantitation of benzidine-positive cells 90 hours after induction by β-estradiol of 12 independent clones from each group. The mean percentage of benzidine-positive cells is slightly lower in the Arg216Gln clones (t test, P = .06). No benzidine-positive cells are observed in the Val205Gly clones. (B) GATA-1/ER protein is expressed at varying levels in wild-type (top) and Arg216 (bottom) clones. Corresponding percentages of benzidine-positive cells 90 hours after induction by β-estradiol (from panel A) in individual clones are indicated below the blots. (C) Benzidine staining of clones of G1E cells following stable introduction of wild-type GATA-1/ER (the ensuing clones are named G1E-ER2) or Arg216Gln GATA-1/ER, or G1E cells alone. Benzidine-positive cells (black) are visible after β-estradiol treatment (right panels) when wt GATA-1/ER or Arg216Gln GATA-1/ER is present. Origninal magnification, × 200. (D) GATA-1/ER protein levels of clones pictured in panel C.