Mechanism for the decrease in the FIP1L1-PDGFRalpha protein level in EoL-1 cells by histone deacetylase inhibitors.
BACKGROUND
Acetylation and deacetylation of proteins occur in cells in response to various stimuli, and are reversibly catalyzed by histone acetyltransferase and histone deacetylase (HDAC), respectively. EoL-1 cells have an FIP1L1-PDGFRA fusion gene that causes transformation of eosinophilic precursor cells into leukemia cells. The HDAC inhibitors apicidin and n-butyrate suppress the proliferation of EoL-1 cells and induce differentiation into eosinophils by a decrease in the protein level of FIP1L1-PDGFRalpha without affecting the mRNA level for FIP1L1-PDGFRA. In this study, we analyzed the mechanism by which the protein level of FIP1L1-PDGFRalpha is decreased by apicidin and n-butyrate.


METHODS
EoL-1 cells were incubated in the presence of the HDAC inhibitors apicidin, trichostatin A or n-butyrate. The protein levels of FIP1L1-PDGFRalpha and phosphorylated eIF-2alpha were determined by Western blotting. Actinomycin D and cycloheximide were used to block RNA synthesis and protein synthesis, respectively, in the chasing experiment of the amount of FIP1L1-PDGFRalpha protein.


RESULTS
When apicidin- and n-butyrate-treated EoL-1 cells were incubated in the presence of actinomycin D, the decrease in the protein level of FIP1L1-PDGFRalpha was significantly enhanced when compared with controls. In contrast, the protein levels were not changed by cycloheximide among these groups. Apicidin and n-butyrate induced the continuous phosphorylation of eIF-2alpha for up to 8 days.


CONCLUSIONS
The decrease in the level of FIP1L1-PDGFRalpha protein by continuous inhibition of HDAC may be due to the decrease in the translation rate of FIP1L1-PDGFRA.
Ishihara
Kenji
K
Laboratory of Pathophysiological Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan. ishihara@wadalab.mech.tohoku.ac.jp
Kaneko
Motoko
M
Kitamura
Hajime
H
Takahashi
Aki
A
Hong
Jang Ja
JJ
Seyama
Toshio
T
Iida
Koji
K
Wada
Hiroshi
H
Hirasawa
Noriyasu
N
Ohuchi
Kazuo
K
D000107:Acetylation / Q000187:drug effects; D015153:Blotting, Western; D002087:Butyrates / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004804:Eosinophils / Q000187:drug effects* / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000188:drug therapy* / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D010456:Peptides, Cyclic / Q000494:pharmacology*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D039221:mRNA Cleavage and Polyadenylation Factors / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism
D002087:Butyrates; D004791:Enzyme Inhibitors; D015852:Eukaryotic Initiation Factor-2; D056572:Histone Deacetylase Inhibitors; D015514:Oncogene Proteins, Fusion; D010456:Peptides, Cyclic; C102351:apicidin; D039221:mRNA Cleavage and Polyadenylation Factors; C479819:FIP1L1-PDGFRA fusion protein, human; D020796:Receptor, Platelet-Derived Growth Factor alpha; D006655:Histone Deacetylases