title: Caspase-mediated specific cleavage of human histone deacetylase 4.
abstract: Histone deacetylase 4 (HDAC4) is a class II HDAC implicated in controlling gene expression important for diverse cellular functions, but little is known about how its expression and stability are regulated. We report here that this deacetylase is unusually unstable, with a half-life of less than 8 h. Consistent with the instability of HDAC4 protein, its mRNA was also highly unstable (with a half-life of less than 4 h). The degradation of HDAC4 could be accelerated by exposure of cells to ultraviolet irradiation. HDAC4 degradation was not dependent on proteasome or CRM1-mediated export activity but instead was caspase-dependent and was detectable in diverse human cancer lines. Of two potential caspase consensus motifs in HDAC4, both lying within a region containing proline-, glutamic acid-, serine-, and threonine-rich (PEST) sequences, we identified, by site-directed mutagenesis, Asp-289 as the prime cleavage site. Notably, this residue is not conserved among other class IIa members, HDAC5, -7, and -9. Finally, the induced expression of caspase-cleavable HDAC4 led to markedly increased apoptosis. These results therefore unexpectedly link the regulation of HDAC4 protein stability to caspases, enzymes that are important for controlling cell death and differentiation.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania School of Medicine, John Morgan 180H, Philadelphia, PA 19104, USA
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Melissa
authors.initials: M
authors.lastname: Dowling
authors.forename: Xiang-Jiao
authors.initials: XJ
authors.lastname: Yang
authors.forename: Gary D
authors.initials: GD
authors.lastname: Kao
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D017209:Apoptosis; D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D001692:Biological Transport; D016466:CHO Cells; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002470:Cell Survival; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004318:Doxycycline / Q000494:pharmacology; D005822:Genetic Vectors; D018698:Glutamic Acid / Q000737:chemistry; D006367:HeLa Cells; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009097:Multienzyme Complexes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011392:Proline / Q000737:chemistry; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000737:chemistry; D013912:Threonine / Q000737:chemistry; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D009097:Multienzyme Complexes; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D012097:Repressor Proteins; D003609:Dactinomycin; D013912:Threonine; D001224:Aspartic Acid; D018698:Glutamic Acid; D012694:Serine; D003513:Cycloheximide; D011392:Proline; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C400300:HDAC4 protein, human; D006655:Histone Deacetylases; D004318:Doxycycline