Histone deacetylase 2 is required for chromatin condensation and subsequent enucleation of cultured mouse fetal erythroblasts.
BACKGROUND
During the final stages of differentiation of mammalian erythroid cells, the chromatin is condensed and enucleated. We previously reported that Rac GTPases and their downstream target, mammalian homolog of Drosophila diaphanous 2 (mDia2), are required for enucleation of in vitro cultured mouse fetal liver erythroblasts. However, it is not clear how chromatin condensation is achieved and whether it is required for enucleation.


METHODS
Mouse fetal liver erythroblasts were purified from embryonic day 14.5 pregnant mice and cultured in erythropoietin-containing medium. Enucleation was determined by flow-cytometry based analysis after treatment with histone deacetylase inhibitors or infection with lentiviral short hairpin RNA.


RESULTS
We showed that histone deacetylases play critical roles in chromatin condensation and enucleation in cultured mouse fetal liver erythroblasts. Enzymatic inhibition of histone deacetylases by trichostatin A or valproic acid prior to the start of enucleation blocked chromatin condensation, contractile actin ring formation and enucleation. We further demonstrated that histone deacetylases 1, 2, 3 and 5 are highly expressed in mouse fetal erythroblasts. Short hairpin RNA down-regulation of histone deacetylase 2, but not of the other histone deacetylases, phenotypically mimicked the effect of trichostatin A or valproic acid treatment, causing significant inhibition of chromatin condensation and enucleation. Importantly, knock-down of histone deacetylase 2 did not affect erythroblast proliferation, differentiation, or apoptosis.


CONCLUSIONS
These results identify histone deacetylase 2 as an important regulator, mediating chromatin condensation and enucleation in the final stages of mammalian erythropoiesis.
Ji
Peng
P
Whitehead Institute for Biomedical Research, Cambridge, 9 Cambridge Center, Cambridge, MA, USA.
Yeh
Victor
V
Ramirez
Tzutzuy
T
Murata-Hori
Maki
M
Lodish
Harvey F
HF
D000107:Acetylation; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism*; D004900:Erythroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004920:Erythropoiesis / Q000187:drug effects; D005260:Female; D005333:Fetus; D056464:Histone Deacetylase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D006877:Hydroxamic Acids / Q000494:pharmacology; D008099:Liver; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D011247:Pregnancy; D034622:RNA Interference; D014635:Valproic Acid / Q000494:pharmacology
D002843:Chromatin; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; C012589:trichostatin A; D014635:Valproic Acid; D056464:Histone Deacetylase 2
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