Molecular Cloning and Characterization of a Novel Histone Deacetylase HDAC10

Abstract

The growing number of proteins controlled by reversible acetylation suggests the existence of a large number of acetyltransferases and deacetylases. Here, we report the identification of a novel class II histone deacetylase, HDAC10. Homology comparison indicates that HDAC10 is most similar to HDAC6. Both contain a unique, putative second catalytic domain not found in other HDACs. In HDAC10, however, this domain is not functional. This tandem organization of two catalytic domains confers resistance to the inhibitors trapoxin B and sodium butyrate, which potently inhibit the deacetylase activity of all other HDAC members. Thus, HDAC10 and HDAC6 share unusual structural and pharmacological characteristics. However, unlike HDAC6, which is normally a cytoplasmic deacetylase, HDAC10 resides in both the nucleus and cytoplasm. In the nucleus, when tethered to a promoter, HDAC10 represses transcription independent of its deacetylase activity, indicating that HDAC10 contains a distinct transcriptional repressor domain. These observations suggest that HDAC10 might uniquely play roles both in the nucleus, as a transcriptional modulator, and in the cytoplasm in an unidentified role. Together, our results identify HDAC10 as a novel deacetylase with distinct structure, pharmacology and localization and further expand the complexity of the HDAC family. The growing number of proteins controlled by reversible acetylation suggests the existence of a large number of acetyltransferases and deacetylases. Here, we report the identification of a novel class II histone deacetylase, HDAC10. Homology comparison indicates that HDAC10 is most similar to HDAC6. Both contain a unique, putative second catalytic domain not found in other HDACs. In HDAC10, however, this domain is not functional. This tandem organization of two catalytic domains confers resistance to the inhibitors trapoxin B and sodium butyrate, which potently inhibit the deacetylase activity of all other HDAC members. Thus, HDAC10 and HDAC6 share unusual structural and pharmacological characteristics. However, unlike HDAC6, which is normally a cytoplasmic deacetylase, HDAC10 resides in both the nucleus and cytoplasm. In the nucleus, when tethered to a promoter, HDAC10 represses transcription independent of its deacetylase activity, indicating that HDAC10 contains a distinct transcriptional repressor domain. These observations suggest that HDAC10 might uniquely play roles both in the nucleus, as a transcriptional modulator, and in the cytoplasm in an unidentified role. Together, our results identify HDAC10 as a novel deacetylase with distinct structure, pharmacology and localization and further expand the complexity of the HDAC family. histone deacetylase sodium butyrate p53 target protein in the deacetylases complexes trapoxin B trichostatin A nuclear localization signal phosphate-buffered saline It has been known for many years that histone acetylation, a post-translational modification on specific lysine residues, is important for regulating the transcription of many genes (1Allfrey V.G. Faulkner R. Mirsky A.E. Proc. Natl, Acad. Sci. U. S. A. 1964; 61: 768-794Google Scholar). It is generally believed that hypo-acetylated histones have an increased charge, allowing chromatin condensation and, consequently, are associated with transcriptionally silent regions. Conversely, hyper-acetylation of histones neutralizes this charge, permitting chromatin decondensation and, thus, is associated with transcriptionally active regions (reviewed by Wade et al.(2Wade P.A. Pruss D. Wolffe A.P. Trends Biochem. Sci. 1997; 22: 128-132Abstract Full Text PDF PubMed Scopus (411) Google Scholar)). The acetylation of these lysine residues is catalyzed by histone acetyltransferases, whereas the removal of the acetyl group is carried out by histone deacetylases (HDACs).1 Recent studies, however, have expanded the substrate repertoire of histone acetyltransferases and HDACs, suggesting that the function of acetylation is not limited to histone metabolism or transcription but may regulate a variety of biological processes. Indeed, acetylation has been shown to regulate the DNA binding activity of several transcription factors (3Boyes J. Byfield P. Nakatani Y. Ogryzko V. Nature. 1998; 396: 594-598Crossref PubMed Scopus (636) Google Scholar, 4Martinez-Balbas M.A. Bauer U.M. Nielsen S.J. Brehm A. Kouzarides T. EMBO J. 2000; 19: 662-671Crossref PubMed Scopus (575) Google Scholar), nuclear import (5Bannister A.J. Miska E.A. Gorlich D. Kouzarides T. Curr. Biol. 2000; 10: 467-470Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar), microtubule function (6Piperno G. LeDizet M. Chang X.J. J. Cell Biol. 1987; 104: 289-302Crossref PubMed Scopus (687) Google Scholar), 2C. Hubbert, A. Guardiola, R. Shao, A. Ito, A. Nixon, M. Yoshida, X. F. Wang, and T.-P. Yao, submitted for publication. and protein-protein interactions (7Waltzer L. Bienz M. Nature. 1998; 395: 521-525Crossref PubMed Scopus (327) Google Scholar). Additionally, acetylation is an important modification in the pathway that leads to p53 activation and stabilization (8Ito A. Lai C.H. Zhao X. Saito S. Hamilton M.H. Appella E. Yao T.P. EMBO J. 2001; 20: 1331-1340Crossref PubMed Scopus (447) Google Scholar). These results suggest that acetylation is a critical post-translational modification that, like phosphorylation, has diverse biological effects. Recent studies have identified nine members of the mammalian HDAC family, and they are divided into two classes, originally defined by size and sequence homology to the yeast prototypic HDACs. The class I HDACs, which are about 400–500 amino acids in size, include HDAC1 (9Taunton J. Hassig C.A. Schreiber S.L. Science. 1996; 272: 408-411Crossref PubMed Scopus (1561) Google Scholar), HDAC2 (10Yang W.M. Inouye C. Zeng Y. Bearss D. Seto E. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 12845-12850Crossref PubMed Scopus (488) Google Scholar), HDAC3 (11Yang W.M. Yao Y.L. Sun J.M. Davie J.R. Seto E. J. Biol. Chem. 1997; 272: 28001-28007Abstract Full Text Full Text PDF PubMed Scopus (406) Google Scholar), and HDAC8 (12Hu E. Chen Z. Fredrickson T. Zhu Y. Kirkpatrick R. Zhang G.F. Johanson K. Sung C.M. Liu R. Winkler J. J. Biol. Chem. 2000; 275: 15254-15264Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar) and share homology to the yeast prototype Rpd3. The larger class II members, all about 1000 amino acids, include HDAC4, HDAC5, HDAC6 (13Grozinger C.M. Hassig C.A. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4868-4873Crossref PubMed Scopus (670) Google Scholar), HDAC7 (14Kao H.Y. Downes M. Ordentlich P. Evans R.M. Genes Dev. 2000; 14: 55-66Crossref PubMed Google Scholar), and HDAC9 (15Zhou X. Marks P.A. Rifkind R.A. Richon V.M. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: 10572-10577Crossref PubMed Scopus (210) Google Scholar) and are homologous to the yeast Hda1p. The complexity of this family is illustrated by the subcellular localization patterns of the two classes. Although the class I HDACs are primarily nuclear, the class II HDAC4 and -5 can shuttle between the nucleus and cytoplasm. Their shuttling is involved in the regulation of myogenesis and controlled by calmodulin-dependent kinase-mediated phosphorylation (16McKinsey T.A. Zhang C.L. Lu J. Olson E.N. Nature. 2000; 408: 106-111Crossref PubMed Scopus (882) Google Scholar,17Zhao X. Ito A. Kane C.D. Liao T.S. Bolger T.A. Lemrow S.M. Means A.R. Yao T.P. J. Biol. Chem. 2001; 276: 35042-35048Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar). Although predominantly nuclear, HDAC7 was found to bind the membrane-associated endothelin receptor A, implying that HDAC7 might also have a function in the cytoplasm (18Lee H.J. Chun M. Kandror K.V. J. Biol. Chem. 2001; 276: 16597-17600Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). Unlike any previously identified HDAC, human HDAC6 is a cytoplasmic deacetylase (19Verdel A. Curtet S. Brocard M.P. Rousseaux S. Lemercier C. Yoshida M. Khochbin S. Curr. Biol. 2000; 10: 747-749Abstract Full Text Full Text PDF PubMed Scopus (187) Google Scholar).2 The discovery of non-histone acetylated proteins and cytoplasmic localization of the class II HDACs implies that acetylation is an important post-translational modification required for the proper regulation of a variety of biological processes. Indeed, HDAC inhibitors such as trichostatin A (TSA) and suberoylamide hydroxamic acid have anti-tumor effects as they can arrest cell growth (20Richon V.M. Emiliani S. Verdin E. Webb Y. Breslow R. Rifkind R.A. Marks P.A. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 3003-3007Crossref PubMed Scopus (854) Google Scholar, 21Yoshida M. Horinouchi S. Beppu T. Bioessays. 1995; 17: 423-430Crossref PubMed Scopus (670) Google Scholar), induce differentiation of transformed cells in culture (21Yoshida M. Horinouchi S. Beppu T. Bioessays. 1995; 17: 423-430Crossref PubMed Scopus (670) Google Scholar, 22Richon V.M. Webb Y. Merger R. Sheppard T. Jursic B. Ngo L. Civoli F. Breslow R. Rifkind R.A. Marks P.A. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 5705-5708Crossref PubMed Scopus (426) Google Scholar), and prevent tumor growth in mice models (23Cohen L.A. Amin S. Marks P.A. Rifkind R.A. Desai D. Richon V.M. Anticancer Res. 1999; 19: 4999-5005PubMed Google Scholar). These results suggest that the inhibition of HDACs is a potential therapeutic approach for more potent cancer treatment. The emerging numbers of diverse and important proteins that are reversibly acetylated argue that different members of the HDAC family have a unique set of substrates and regulate different biological processes. Therefore, the identification of all acetyltransferases and deacetylases might hold significant insight into the full picture and complexity of acetylation biology. Here we report the identification of a novel histone deacetylase, HDAC10. Our analysis indicates that HDAC10 is most similar to HDAC6. Both HDAC10 and -6 contain two spaced catalytic domains. Although the second catalytic domain in HDAC10 is not functional, its presence confers resistance to the inhibitors trapoxin B (TPX-B) and sodium butyrate (NaB). Despite their similar structural and pharmacological characteristics, HDAC10 and HDAC6 localize to different subcellular compartments. Unique among all the HDACs identified so far, HDAC10 resides in both the nuclear and cytoplasmic compartments. In the nucleus, HDAC10 is capable of repressing transcription via a deacetylase-independent mechanism. Therefore, our results suggest that HDAC10 is a novel deacetylase that could have both nuclear and cytoplasmic functions. The amino acid sequence of HDAC6 catalytic domains (amino acids 138–782) was used in a protein-protein BLAST search of the NCBI data base for novel class II HDACs. A putative deacetylase was found in a bacterial clone of chromosome 22q13.31–13.33 (GenBankTM accession number AL022328). Sequence-specific primers were used to generate a C-terminal FLAG-tagged HDAC10 by PCR from a K562 library (PCR primers: 5′ primer, 5′-GCGGTACCATGGGGACCGCGCTTGTGTACCAT-3′ and 5′-GGAATTCTTTATCATCATCATCTTTATAGTCAGCCACCAGGTGAGGATGG-3′) and inserted at the KpnI and EcoRI sites of pCMX-PL2. The FLAG tag was incorporated into the reverse primer. The Gal4-HDAC10-NLS construct was generated by PCR using the same 5′ primer and a 3′ primer including the SV40 NLS (5′-GAAGATCTACTTACCTTTCTCTTCTTTTTTGGTTTATCATCATCATCTTTATAGTC-3′). The HDAC10pCMX-PL2 H135A mutant was generated using the QuikChange site-directed mutagenesis kit (Stratagene). U2OS cells were maintained in Dulbecco's modified Eagle's medium supplemented with 10% fetal clone serum, penicillin/streptomycin and grown at 37 °C humidified atmosphere with 5% CO2. 293T cells were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, penicillin/streptomycin and grown at 37 °C at 5% CO2. Transfections were done using the calcium phosphate method (24Yao T.P. Segraves W.A. Oro A.E. McKeown M. Evans R.M. Cell. Full Text PDF PubMed Scopus Google Scholar). and were by Zhang of at and to were by were by E. of were in for at °C and by at for of protein were with the of and of protein for The proteins were by and to were in of of were by with protein for at were as HDAC were in a HDACs, 10% and were with or for on the of were for at 37 of was and of was to the was in a U2OS cells were on in cells were with the FLAG-tagged HDAC cells were with B for were for with in with and with for in 10% serum, cells were with the in in for at with and with for by with were using a U2OS cells were in the cells were with of DNA including DNA binding and the as in were activity was as in Yao et (24Yao T.P. Segraves W.A. Oro A.E. McKeown M. Evans R.M. Cell. Full Text PDF PubMed Scopus Google Scholar) and by protein The amino acid sequence of the HDAC6 catalytic domains was used to the NCBI data base for novel human class II HDACs. The search identified a novel HDAC on chromosome that we HDAC10. by the HDAC10 has two that are and in their most C-terminal shown in the the which contains an the at base an a so that the into on the HDAC10 primers were and used to the sequence of by PCR from a K562 shown in has a sequence of base and an amino acid sequence of amino acids the sequence by (amino acids The presence of these amino acids in the sequence is to an of the of and the of potential post-translational modification sites were including a at putative protein phosphorylation and several putative II phosphorylation sites these sites are modified in to are also of regions that could as potential nuclear for the HDAC10 The and are a which contains an in a and an in amino acid sequence for number originally submitted the sequence as However, the of this HDAC, which is a of transcriptional repressor was (15Zhou X. Marks P.A. Rifkind R.A. Richon V.M. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: 10572-10577Crossref PubMed Scopus (210) Google Scholar). our clone HDAC10, and the number this amino acids for is potential regions or post-translational modification sites are as A putative is potential phosphorylation sites potential II phosphorylation sites are also regions that could as potential nuclear localization are sequence of the catalytic domain and regions of human HDAC4 (13Grozinger C.M. Hassig C.A. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4868-4873Crossref PubMed Scopus (670) Google HDAC6 (13Grozinger C.M. Hassig C.A. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4868-4873Crossref PubMed Scopus (670) Google and The catalytic domain is by the analysis of the known mammalian histone deacetylases and the yeast of the deacetylase I and The were used for (9Taunton J. Hassig C.A. Schreiber S.L. Science. 1996; 272: 408-411Crossref PubMed Scopus (1561) Google Scholar), (10Yang W.M. Inouye C. Zeng Y. Bearss D. Seto E. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 12845-12850Crossref PubMed Scopus (488) Google Scholar), (11Yang W.M. Yao Y.L. Sun J.M. Davie J.R. Seto E. J. Biol. Chem. 1997; 272: 28001-28007Abstract Full Text Full Text PDF PubMed Scopus (406) Google Scholar), (13Grozinger C.M. Hassig C.A. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4868-4873Crossref PubMed Scopus (670) Google Scholar), (14Kao H.Y. Downes M. Ordentlich P. Evans R.M. Genes Dev. 2000; 14: 55-66Crossref PubMed Google Scholar), E. Chen Z. Fredrickson T. Zhu Y. Kirkpatrick R. Zhang G.F. Johanson K. Sung C.M. Liu R. Winkler J. J. Biol. Chem. 2000; 275: 15254-15264Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar). of several class II histone deacetylases. The histone deacetylase catalytic domain is as as the transcriptional repressor homologous domain of human HDAC4 and a homology domain in human HDAC6. The the putative nuclear of analysis that HDAC10 is most homologous to the class II HDACs. It is 37 and to HDAC4 and HDAC6, with the of homology between regions and including the catalytic domains analysis the that HDAC6 and HDAC10 are more to other to the other class II deacetylases Unlike all other previously identified HDACs, HDAC6 and HDAC10 contain an catalytic a and a second C-terminal catalytic domain The C-terminal catalytic domain of HDAC10, however, is and the active residues required for activity J.R. A. Richon V.M. Rifkind R.A. Marks P.A. Breslow R. Nature. 1999; PubMed Scopus Google Scholar). Thus, unlike HDAC6, which has two catalytic sequence analysis suggests that HDAC10 has active domain. these sequence suggest that HDAC10 is a novel class II histone deacetylase in a with HDAC6. HDAC10 as a deacetylase and the second catalytic domain of HDAC10 is functional. this we generated a mutant of HDAC10 to the catalytic domain. FLAG-tagged of several class II HDACs and the HDAC10 H135A mutant were into 293T with and using a histone by analysis of cell HDAC4, and the HDAC10 H135A mutant were at similar HDAC10 was at about in with the shown in HDAC10 deacetylase activity, HDAC6 activity was both HDAC4 and of its two independent catalytic domains. HDAC10 activity was to a potent HDAC the HDAC10 H135A mutant activity, that the second catalytic domain of HDAC10 is not a deacetylase domain Although all mammalian deacetylases are by a report has shown that HDAC6 is to the HDAC R. Y. Khochbin S. Yoshida M. Horinouchi S. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: PubMed Scopus Google Scholar). shown in HDAC6 activity is to we have found that HDAC6 is also to of the sequence between HDAC6 and we to HDAC10 also this pharmacological of HDAC6. shown in HDAC1 activity was by all inhibitors In the activity of HDAC10 was more to and Thus, similar to HDAC6, HDAC10 also resistance to and two can this unique pharmacological of HDAC6 and their catalytic domain might resistance to and the presence of the second or catalytic domain this to and both of the catalytic domains of HDAC6 are (13Grozinger C.M. Hassig C.A. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4868-4873Crossref PubMed Scopus (670) Google Scholar), we a mutant that the catalytic domain of HDAC6, to between these two shown in the HDAC6 mutant was to these suggesting that the catalytic domain is not for this the second we an HDAC10 mutant that the C-terminal catalytic domain. This HDAC10 C-terminal mutant similar to and as to suggesting that the presence of two catalytic domains is to this resistance these results further the that HDAC6 and HDAC10 a the class II deacetylases their similar pharmacological are unlike any other known The subcellular localization of the class II deacetylases their roles in regulating distinct processes. to identify the subcellular localization of HDAC10, a FLAG-tagged HDAC10 construct was into U2OS and the localization of HDAC10 was by In to HDAC6, which an cytoplasmic HDAC10 both to the nucleus and the cytoplasm The nuclear to the In most the nuclear was more the cytoplasmic The cytoplasmic of HDAC10, however, is most not an of the the same of and was in cell that we have not the presence of putative nuclear the cytoplasmic localization of HDAC10 was not to B an of suggesting that the cytoplasmic localization of HDAC10 is not a of nuclear The in HDAC6 and HDAC10 suggests that these class II HDACs are involved in different processes. The nuclear localization of HDAC10 to has transcription nuclear localization of HDAC10, an was generated that incorporated the SV40 NLS signal as a C-terminal to FLAG-tagged The of HDAC10 on a binding was by of this with the Gal4-HDAC10-NLS shown in similar to a known HDAC4, Gal4-HDAC10-NLS transcription in a the that HDAC10 can function as a transcriptional the of the also activity, suggesting that HDAC10 contains an active transcription domain independent of its deacetylase a nuclear HDAC1 in several complexes including the and complexes (reviewed in and Cell. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar)). These transcription complexes contain a to other complexes of and a histone HDAC10 represses transcription by with factors of the or a of was with to factors unique to the as as all of these factors to with FLAG-tagged HDAC1 its in transcription of these proteins were in the HDAC10 indicating that HDAC10 is in a distinct from HDAC1 in the identification of HDAC10, are class I deacetylases and class II HDACs in to at more HDAC, which a class Ito, K. and T.-P. Yao, analysis that HDAC10 is most to HDAC6, a unique of the class II HDACs. analysis indicates that HDAC10 and HDAC6 a the class II they are in a from the other known class II HDACs, HDAC4, and Indeed, unlike any other class II members, these two HDACs share a similar domain in that they contain two spaced catalytic with HDAC10 a second domain. Although all the known mammalian deacetylases are to they different to and et R. Y. Khochbin S. Yoshida M. Horinouchi S. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: PubMed Scopus Google Scholar) have previously that HDAC6 is to the In this we for the that HDAC6 is also to Our analysis of HDAC10 that is also to these two inhibitors in to all other which are to and This unique pharmacological of both HDAC6 and HDAC10, further the that they a of the class II deacetylases. is the for this unique pharmacological is an that and the et R. Y. Khochbin S. Yoshida M. Horinouchi S. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: PubMed Scopus Google Scholar) suggest that HDAC6 is to to R. Y. Khochbin S. Yoshida M. Horinouchi S. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: PubMed Scopus Google Scholar). However, HDAC6 is also to a acid that not inhibit HDACs by this is Our that the HDAC6 mutant with an catalytic domain to these inhibitors that is that the of the catalytic domains of HDAC6 or is for the or the presence of a second catalytic of is functional, is the for this Indeed, the of the second catalytic domain of HDAC10 to and that the two catalytic domains to a that binding to but not or this argue that the second catalytic domain may not involved in as in the of HDAC10, to the and, consequently, to the function of HDAC10 and HDAC6. the of the catalytic domain of histone protein J.R. A. Richon V.M. Rifkind R.A. Marks P.A. Breslow R. Nature. 1999; PubMed Scopus Google Scholar), a of the HDAC6 or HDAC10 catalytic domains and to this in to the HDAC4 and HDAC5, which in to regulate the that the homologous HDAC6 and HDAC10 function in similar biological is not by in deacetylase HDAC10 not deacetylase activity an HDAC6 Their subcellular localization is also different these two deacetylases not to in not Thus, in sequence and pharmacological HDAC6 and HDAC10 have different in further the repertoire of the HDAC family. The diverse of the class II HDACs are by their subcellular localization they all or cytoplasmic with this HDAC10 is found both in the nucleus and in the cytoplasm the same in to the shuttling HDAC4 and cytoplasmic HDAC6. HDAC10 cytoplasmic localization is not by B. HDAC10 has putative nuclear these results that these are or HDAC10 is a protein and is in the cytoplasm. Additionally, this subcellular localization suggests that HDAC10 may play several in transcription as as in an unidentified in the cytoplasm. Indeed, when tethered to HDAC10 has transcription activity in to which catalytic activity for its transcription activity C.A. T. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: PubMed Scopus Google Scholar), is independent of its catalytic activity This deacetylase has also been for HDAC4, which contains several repressor domains that are independent of its catalytic domain. Zhao and T.-P. Yao, It is that the is to an associated HDAC deacetylases have been shown to with other (13Grozinger C.M. Hassig C.A. Schreiber S.L. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4868-4873Crossref PubMed Scopus (670) Google Scholar). This is however, deacetylase activity with the HDAC10 mutant with this has a on not the activity is not to the or complexes the of a defined nuclear localization signal implies that the nuclear localization of HDAC10 is most by with a transcription of potential of HDAC10 in both the nucleus and cytoplasm to its studies that HDAC inhibitors have activity in culture cells and in mice T. K. K. S. T. E. J. 2000; PubMed Scopus Google Scholar, in Scholar, T. S. S. F. K. J. PubMed Scopus Google Scholar, A. T. Y. Y. K. T. T. T. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: PubMed Scopus Google Scholar). However, all the HDACs or members of the deacetylases are of the This report with that by et R. Y. Khochbin S. Yoshida M. Horinouchi S. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: PubMed Scopus Google Scholar) that is to that inhibit a of the HDAC family. These not the critical to the unique of a HDAC but also might have the potential to function as specific cancer therapeutic with Y. Zhang for to and for E. for M. Yoshida for and S. Schreiber and C. M. for the HDAC6 and HDAC6 mutant also T. J. T. and X. F. Wang, and D. for critical of this