CCAR1/CoCoA pair-mediated recruitment of the Mediator defines a novel pathway for GATA1 function.
The MED1 subunit of the Mediator transcriptional coregulator complex coactivates GATA1 and induces erythropoiesis. Here, we show the dual mechanism of GATA1- and MED1-mediated transcription. MED1 expression levels in K562 erythroleukemia cells paralleled the levels of GATA1-targeted gene transcription and erythroid differentiation. An N-terminal fragment of MED1, MED1(1-602), which is incapable of interacting with GATA1, enhanced GATA1-targeted gene transcription and erythroid differentiation, and introduction of MED1(1-602) into Med1(-/-) mouse embryonic fibroblasts (MEFs) partially rescued GATA1-mediated transcription. The C-terminal zinc-finger domain of GATA1 interacts with the MED1(1-602)-interacting coactivator CCAR1, CoCoA and MED1(681-715). CCAR1 and CoCoA synergistically enhanced GATA1-mediated transcription from the γ-globin promoter in MEFs. Recombinant GATA1, CCAR1, CoCoA and MED1(1-602) formed a complex in vitro, and GATA1, CCAR1, CoCoA and MED1 were recruited to the γ-globin promoter in K562 cells during erythroid differentiation. Therefore, in addition to the direct interaction between GATA1 and MED1, CoCoA and CCAR1 appear to relay the GATA1 signal to MED1, and multiple modes of the GATA1-MED1 axis may help to fine-tune GATA1 function during GATA1-mediated homeostasis events.
Laboratory of Hematology, Division of Medical Biophysics, Kobe University Graduate School of Health Sciences, Kobe, 654-0142, Japan.
Shumpei
S
Mizuta
Tomoya
T
Minami
Haruka
H
Fujita
Chihiro
C
Kaminaga
Keiji
K
Matsui
Ruri
R
Ishino
Azusa
A
Fujita
Kasumi
K
Oda
Asami
A
Kawai
Natsumi
N
Hasegawa
Norinaga
N
Urahama
Robert G
RG
Roeder
Mitsuhiro
M
Ito
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D050982:GATA1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D008297:Male; D056913:Mediator Complex Subunit 1 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D055545:gamma-Globins / Q000235:genetics
D051017:Apoptosis Regulatory Proteins; C540324:CCAR1 protein, mouse; D002135:Calcium-Binding Proteins; C586920:Calcoco1 protein, mouse; D018797:Cell Cycle Proteins; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; C494689:Gata1 protein, mouse; C538855:MED1 protein, human; D056913:Mediator Complex Subunit 1; D014157:Transcription Factors; D055545:gamma-Globins