TY - JOUR
T1 - Functions of BET proteins in erythroid gene expression
AU - Stonestrom, Aaron J.
AU - Hsu, Sarah C.
AU - Jahn, Kristen S.
AU - Huang, Peng
AU - Keller, Cheryl A.
AU - Giardine, Belinda M.
AU - Kadauke, Stephan
AU - Campbell, Amy E.
AU - Evans, Perry
AU - Hardison, Ross C.
AU - Blobel, Gerd A.
N1 - Funding Information:
The authors thank Christopher Vakoc and Chris Hsiung for helpful discussion, Ryan Wychowanec and Hetty Rodriguez for technical assistance, and James Bradner for JQ1. This work was supported by National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases grants R01-DK054937 (G.A.B.), R56-DK065806 (R.C.H., G.A.B), and T32-DK007780 (A.J.S.), National Cancer Institute grant F30-CA189553 (S.C.H.), and a generous donation by the DiGaetano family (G.A.B., P.E.).
Publisher Copyright:
© 2015 by The American Society of Hematology.
PY - 2015
Y1 - 2015
N2 - Inhibitors of bromodomain and extraterminal motif proteins (BETs) are being evaluated for the treatment of cancer and other diseases, yet much remains to be learned about how BET proteins function during normal physiology. We used genomic and genetic approaches to examine BET function in a hematopoietic maturation system driven by GATA1, an acetylated transcription factor previously shown to interact with BETs. We found that BRD2, BRD3, and BRD4 were variably recruited to GATA1-regulated genes, with BRD3 binding the greatest number of GATA1-occupied sites. Pharmacologic BET inhibition impaired GATA1-mediated transcriptional activation, but not repression, genome-wide. Mechanistically, BETs promoted chromatin occupancy of GATA1 and subsequently supported transcriptional activation. Using a combination of CRISPR-Cas9-mediated genomic engineering and shRNA approaches, we observed that depletion of either BRD2 or BRD4 alone blunted erythroid gene activation. Surprisingly, depletion of BRD3 only affected erythroid transcription in the context of BRD2 deficiency. Consistent with functional overlap among BET proteins, forced BRD3 expression substantially rescued defects caused by BRD2 deficiency. These results suggest that pharmacologic BET inhibition should be interpreted in the context of distinct steps in transcriptional activation and overlapping functions among BET family members.
AB - Inhibitors of bromodomain and extraterminal motif proteins (BETs) are being evaluated for the treatment of cancer and other diseases, yet much remains to be learned about how BET proteins function during normal physiology. We used genomic and genetic approaches to examine BET function in a hematopoietic maturation system driven by GATA1, an acetylated transcription factor previously shown to interact with BETs. We found that BRD2, BRD3, and BRD4 were variably recruited to GATA1-regulated genes, with BRD3 binding the greatest number of GATA1-occupied sites. Pharmacologic BET inhibition impaired GATA1-mediated transcriptional activation, but not repression, genome-wide. Mechanistically, BETs promoted chromatin occupancy of GATA1 and subsequently supported transcriptional activation. Using a combination of CRISPR-Cas9-mediated genomic engineering and shRNA approaches, we observed that depletion of either BRD2 or BRD4 alone blunted erythroid gene activation. Surprisingly, depletion of BRD3 only affected erythroid transcription in the context of BRD2 deficiency. Consistent with functional overlap among BET proteins, forced BRD3 expression substantially rescued defects caused by BRD2 deficiency. These results suggest that pharmacologic BET inhibition should be interpreted in the context of distinct steps in transcriptional activation and overlapping functions among BET family members.
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U2 - 10.1182/blood-2014-10-607309
DO - 10.1182/blood-2014-10-607309
M3 - Article
C2 - 25696920
AN - SCOPUS:84964697666
VL - 125
SP - 2825
EP - 2834
JO - Blood
JF - Blood
SN - 0006-4971
IS - 18
ER -
