Disease-modifying therapies are needed for Fragile X Syndrome (FXS), as at present there are no effective treatments or cures. Herein, we report on a tetrahydroquinoline-based selective histone deacetylase 6 (HDAC6) inhibitor SW-100, its pharmacological and ADMET properties, and its ability to improve upon memory performance in a mouse model of FXS, Fmr1-/- mice. This small molecule demonstrates good brain penetrance, low-nanomolar potency for the inhibition of HDAC6 (IC50 = 2.3 nM), with at least a thousand-fold selectivity over all other class I, II, and IV HDAC isoforms. Moreover, through its inhibition of the α-tubulin deacetylase domain of HDAC6 (CD2), in cells SW-100 upregulates α-tubulin acetylation with no effect on histone acetylation and selectively restores the impaired acetylated α-tubulin levels in the hippocampus of Fmr1-/- mice. Lastly, SW-100 ameliorates several memory and learning impairments in Fmr1-/- mice, thus modeling the intellectual deficiencies associated with FXS, and hence providing a strong rationale for pursuing HDAC6-based therapies for the treatment of this rare disease.

Department of Medicinal Chemistry and Pharmacognosy College of Pharmacy University of Illinois at Chicago Chicago Illinois 60612 United States

Department of Psychiatry and Behavioral Sciences Miller School of Medicine University of Miami Miami Florida 33136 United States

Division of Genetics and Development Krembil Research Institute University Health Network Toronto Ontario M5G 2C4 Canada

Laboratory of Neurobiology Center for Brain and Disease KU Leuven B 3000 Leuven Belgium

Laboratory of Structural Biology Institute of Biotechnology of the Czech Academy of Sciences Prumyslova 595 252 50 Vestec Czech Republic

Promega Corporation Madison Wisconsin 53711 United States

StarWise Therapeutics LLC Madison Wisconsin 53719 United States

Zobrazit více v PubMed

Prevalence of Fragile X Syndrome: https://fragilex.org/understanding-fragile-x/fragile-x-101/prevalence/ (accessed Oct. 20, 2018).

Penagarikano O, Mulle JG, and Warren ST (2007) The pathophysiology of fragile x syndrome. Annu. Rev. Genomics Hum. Genet 8, 109–29. PubMed

Khandjian EW, Corbin F, Woerly S, and Rousseau F (1996) The fragile X mental retardation protein is associated with ribosomes. Nat. Genet 12, 91–3. PubMed

Laggerbauer B, Ostareck D, Keidel EM, Ostareck-Lederer A, and Fischer U (2001) Evidence that fragile X mental retardation protein is a negative regulator of translation. Hum. Mol. Genet 10, 329–38. PubMed

Darnell JC, Van Driesche SJ, Zhang C, Hung KY, Mele A, Fraser CE, Stone EF, Chen C, Fak JJ, Chi SW, Licatalosi DD, Richter JD, and Darnell RB (2011) FMRP stalls ribosomal translocation on mRNAs linked to synaptic function and autism. Cell 146, 247–61. PubMed PMC

Bear MF, Huber KM, and Warren ST (2004) The mGluR theory of fragile X mental retardation. Trends Neurosci 27, 370–7. PubMed

Michalon A, Sidorov M, Ballard TM, Ozmen L, Spooren W, Wettstein JG, Jaeschke G, Bear MF, and Lindemann L (2012) Chronic pharmacological mGlu5 inhibition corrects fragile X in adult mice. Neuron 74, 49–56. PubMed PMC

Krueger DD, and Bear MF (2011) Toward fulfilling the promise of molecular medicine in fragile X syndrome. Annu. Rev. Med 62, 411–29. PubMed PMC

Youssef EA, Berry-Kravis E, Czech C, Hagerman RJ, Hessl D, Wong CY, Rabbia M, Deptula D, John A, Kinch R, Drewitt P, Lindemann L, Marcinowski M, Langland R, Horn C, Fontoura P, Santarelli L, Quiroz JA, and FragXis Study, G. (2018) Effect of the mGluR5-NAM Basimglurant on Behavior in Adolescents and Adults with Fragile X Syndrome in a Randomized, Double-Blind, Placebo-Controlled Trial: FragXis Phase 2 Results. Neuropsychopharmacology 43, 503–12. PubMed PMC

Scharf SH, Jaeschke G, Wettstein JG, and Lindemann L (2015) Metabotropic glutamate receptor 5 as drug target for Fragile X syndrome. Curr. Opin. Pharmacol 20, 124–34. PubMed

Davenport MH, Schaefer TL, Friedmann KJ, Fitzpatrick SE, and Erickson CA (2016) Pharmacotherapy for Fragile X Syndrome: Progress to Date. Drugs 76, 431–45. PubMed

Torrioli M, Vernacotola S, Setini C, Bevilacqua F, Martinelli D, Snape M, Hutchison JA, Di Raimo FR, Tabolacci E, and Neri G (2010) Treatment with valproic acid ameliorates ADHD symptoms in fragile X syndrome boys. Am. J. Med. Genet., Part A 152A, 1420–7. PubMed

Tabolacci E, De Pascalis I, Accadia M, Terracciano A, Moscato U, Chiurazzi P, and Neri G (2008) Modest reactivation of the mutant FMR1 gene by valproic acid is accompanied by histone modifications but not DNA demethylation. Pharmacogenet. Genomics 18, 738–41. PubMed

Penney J, and Tsai LH (2014) Histone deacetylases in memory and cognition. Sci. Signaling 7, re12. PubMed

Guan JS, Haggarty SJ, Giacometti E, Dannenberg JH, Joseph N, Gao J, Nieland TJ, Zhou Y, Wang X, Mazitschek R, Bradner JE, DePinho RA, Jaenisch R, and Tsai LH (2009) HDAC2 negatively regulates memory formation and synaptic plasticity. Nature 459, 55–60. PubMed PMC

Kim MS, Akhtar MW, Adachi M, Mahgoub M, Bassel-Duby R, Kavalali ET, Olson EN, and Monteggia LM (2012) An essential role for histone deacetylase 4 in synaptic plasticity and memory formation. J. Neurosci 32, 10879–86. PubMed PMC

McQuown SC, Barrett RM, Matheos DP, Post RJ, Rogge GA, Alenghat T, Mullican SE, Jones S, Rusche JR, Lazar MA, and Wood MA (2011) HDAC3 is a critical negative regulator of long-term memory formation. J. Neurosci 31, 764–74. PubMed PMC

Tang BL (2014) Class II HDACs and neuronal regeneration. J. Cell. Biochem 115, 1225–33. PubMed

Pardo M, Cheng Y, Velmeshev D, Magistri M, Eldar-Finkelman H, Martinez A, Faghihi MA, Jope RS, and Beurel E (2017) Intranasal siRNA administration reveals IGF2 deficiency contributes to impaired cognition in Fragile X syndrome mice. JCI insight 2, No. e91782. PubMed PMC

de Ruijter AJ, van Gennip AH, Caron HN, Kemp S, and van Kuilenburg AB (2003) Histone deacetylases (HDACs): characterization of the classical HDAC family. Biochem. J 370, 737–49. PubMed PMC

Boyault C, Sadoul K, Pabion M, and Khochbin S (2007) HDAC6, at the crossroads between cytoskeleton and cell signaling by acetylation and ubiquitination. Oncogene 26, 5468–76. PubMed

Matthias P, Yoshida M, and Khochbin S (2008) HDAC6 a new cellular stress surveillance factor. Cell Cycle 7, 7–10. PubMed

Li T, Zhang C, Hassan S, Liu X, Song F, Chen K, Zhang W, and Yang J (2018) Histone deacetylase 6 in cancer. J. Hematol. Oncol 11, 111. PubMed PMC

Perdiz D, Mackeh R, Pous C, and Baillet A (2011) The ins and outs of tubulin acetylation: more than just a post-translational modification? Cell. Signalling 23, 763–71. PubMed

Arce CA, Casale CH, and Barra HS (2008) Submembraneous microtubule cytoskeleton: regulation of ATPases by interaction with acetylated tubulin. FEBS J 275, 4664–74. PubMed

Hammond JW, Huang CF, Kaech S, Jacobson C, Banker G, and Verhey KJ (2010) Posttranslational modifications of tubulin and the polarized transport of kinesin-1 in neurons. Mol. Biol. Cell 21, 572–83. PubMed PMC

Hirokawa N, Niwa S, and Tanaka Y (2010) Molecular motors in neurons: transport mechanisms and roles in brain function, development, and disease. Neuron 68, 610–38. PubMed

Gardiner J, Barton D, Marc J, and Overall R (2007) Potential role of tubulin acetylation and microtubule-based protein trafficking in familial dysautonomia. Traffic 8, 1145–9. PubMed

Liu XA, Rizzo V, and Puthanveettil SV (2012) Pathologies of Axonal Transport in Neurodegenerative Diseases. Transl. Neurosci 3, 355–72. PubMed PMC

Jochems J, Boulden J, Lee BG, Blendy JA, Jarpe M, Mazitschek R, Van Duzer JH, Jones S, and Berton O (2014) Antidepressant-like properties of novel HDAC6-selective inhibitors with improved brain bioavailability. Neuropsychopharmacology 39, 389–400. PubMed PMC

Wang Z, Leng Y, Wang J, Liao HM, Bergman J, Leeds P, Kozikowski A, and Chuang DM (2016) Tubastatin A, an HDAC6 inhibitor, alleviates stroke-induced brain infarction and functional deficits: potential roles of alpha-tubulin acetylation and FGF-21 up-regulation. Sci. Rep 6, 19626. PubMed PMC

Pinho BR, Reis SD, Guedes-Dias P, Leitao-Rocha A, Quintas C, Valentao P, Andrade PB, Santos MM, and Oliveira JM (2016) Pharmacological modulation of HDAC1 and HDAC6 in vivo in a zebrafish model: Therapeutic implications for Parkinson’s disease. Pharmacol. Res 103, 328–39. PubMed

Zhang L, Liu C, Wu J, Tao JJ, Sui XL, Yao ZG, Xu YF, Huang L, Zhu H, Sheng SL, and Qin C (2014) Tubastatin A/ACY-1215 improves cognition in Alzheimer’s disease transgenic mice. J. Alzheimer’s Dis 41, 1193–205. PubMed

Zhang L, Sheng S, and Qin C (2013) The role of HDAC6 in Alzheimer’s disease. J. Alzheimer’s Dis 33, 283–95. PubMed

Selenica ML, Benner L, Housley SB, Manchec B, Lee DC, Nash KR, Kalin J, Bergman JA, Kozikowski A, Gordon MN, and Morgan D (2014) Histone deacetylase 6 inhibition improves memory and reduces total tau levels in a mouse model of tau deposition. Alzheimer’s Res. Ther 6, 12. PubMed PMC

d’Ydewalle C, Krishnan J, Chiheb DM, Van Damme P, Irobi J, Kozikowski AP, Vanden Berghe P, Timmerman V, Robberecht W, and Van Den Bosch L (2011) HDAC6 inhibitors reverse axonal loss in a mouse model of mutant HSPB1-induced Charcot-Marie-Tooth disease. Nat. Med 17, 968–74. PubMed

Kim JY, Woo SY, Hong YB, Choi H, Kim J, Choi H, Mook-Jung I, Ha N, Kyung J, Koo SK, Jung SC, and Choi BO (2016) HDAC6 Inhibitors Rescued the Defective Axonal Mitochondrial Movement in Motor Neurons Derived from the Induced Pluripotent Stem Cells of Peripheral Neuropathy Patients with HSPB1Mutation. Stem Cells Int 2016, 9475981. PubMed PMC

Benoy V, Vanden Berghe P, Jarpe M, Van Damme P, Robberecht W, and Van Den Bosch L (2017) Development of Improved HDAC6 Inhibitors as Pharmacological Therapy for Axonal Charcot-Marie-Tooth Disease. Neurotherapeutics 14, 417–28. PubMed PMC

Gold WA, Lacina TA, Cantrill LC, and Christodoulou J (2015) MeCP2 deficiency is associated with reduced levels of tubulin acetylation and can be restored using HDAC6 inhibitors. J. Mol. Med 93, 63–72. PubMed

Guo W, Naujock M, Fumagalli L, Vandoorne T, Baatsen P, Boon R, Ordovas L, Patel A, Welters M, Vanwelden T, Geens N, Tricot T, Benoy V, Steyaert J, Lefebvre-Omar C, Boesmans W, Jarpe M, Sterneckert J, Wegner F, Petri S, Bohl D, Vanden Berghe P, Robberecht W, Van Damme P, Verfaillie C, and Van Den Bosch L (2017) HDAC6 inhibition reverses axonal transport defects in motor neurons derived from FUS-ALS patients. Nat. Commun 8, 861. PubMed PMC

Ross-Inta C, Omanska-Klusek A, Wong S, Barrow C, Garcia-Arocena D, Iwahashi C, Berry-Kravis E, Hagerman RJ, Hagerman PJ, and Giulivi C (2010) Evidence of mitochondrial dysfunction in fragile X-associated tremor/ataxia syndrome. Biochem. J 429, 545–52. PubMed PMC

Kaplan ES, Cao Z, Hulsizer S, Tassone F, Berman RF, Hagerman PJ, and Pessah IN (2012) Early mitochondrial abnormalities in hippocampal neurons cultured from Fmr1 pre-mutation mouse model. J. Neurochem 123, 613–21. PubMed PMC

Chen S, Owens GC, Makarenkova H, and Edelman DB (2010) HDAC6 regulates mitochondrial transport in hippocampal neurons. PLoS One 5, No. e10848. PubMed PMC

Xu X, Kozikowski AP, and Pozzo-Miller L (2014) A selective histone deacetylase-6 inhibitor improves BDNF trafficking in hippocampal neurons from Mecp2 knockout mice: implications for Rett syndrome. Front. Cell. Neurosci 8, 68. PubMed PMC

Uutela M, Lindholm J, Louhivuori V, Wei H, Louhivuori LM, Pertovaara A, Akerman K, Castren E, and Castren ML (2012) Reduction of BDNF expression in Fmr1 knockout mice worsens cognitive deficits but improves hyperactivity and sensorimotor deficits. Genes Brain Behav 11, 513–23. PubMed

Langley B, D’Annibale MA, Suh K, Ayoub I, Tolhurst A, Bastan B, Yang L, Ko B, Fisher M, Cho S, Beal MF, and Ratan RR (2008) Pulse inhibition of histone deacetylases induces complete resistance to oxidative death in cortical neurons without toxicity and reveals a role for cytoplasmic p21(waf1/cip1) in cell cycle-independent neuroprotection. J. Neurosci 28, 163–76. PubMed PMC

Rivieccio MA, Brochier C, Willis DE, Walker BA, D’Annibale MA, McLaughlin K, Siddiq A, Kozikowski AP, Jaffrey SR, Twiss JL, Ratan RR, and Langley B (2009) HDAC6 is a target for protection and regeneration following injury in the nervous system. Proc. Natl. Acad. Sci. U. S. A 106, 19599–604. PubMed PMC

Wang XX, Wan RZ, and Liu ZP (2018) Recent advances in the discovery of potent and selective HDAC6 inhibitors. Eur. J. Med. Chem 143, 1406–18. PubMed

Yee AJ, Bensinger WI, Supko JG, Voorhees PM, Berdeja JG, Richardson PG, Libby EN, Wallace EE, Birrer NE, Burke JN, Tamang DL, Yang M, Jones SS, Wheeler CA, Markelewicz RJ, and Raje NS (2016) Ricolinostat plus lenalidomide, and dexamethasone in relapsed or refractory multiple myeloma: a multicentre phase 1b trial. Lancet Oncol 17, 1569–78. PubMed

Clinical trials for ACY-1215 https://clinicaltrials.gov/ct2/results?term=ACY-1215&Search=Search (accessed Sep. 28, 2018).

Clinical trials for ACY-241 https://clinicaltrials.gov/ct2/results?term=ACY-241&Search=Search (accessed Sep. 28, 2018).

Lee HY, Fan SJ, Huang FI, Chao HY, Hsu KC, Lin TE, Yeh TK, Lai MJ, Li YH, Huang HL, Yang CR, and Liou JP (2018) 5-Aroylindoles Act as Selective Histone Deacetylase 6 Inhibitors Ameliorating Alzheimer’s Disease Phenotypes. J. Med. Chem 61, 7087–102. PubMed

Fan SJ, Huang FI, Liou JP, and Yang CR (2018) The novel histone de acetylase 6 inhibitor, MPT0G211, ameliorates tau phosphorylation and cognitive deficits in an Alzheimer’s disease model. Cell Death Dis 9, 655. PubMed PMC

Yu CW, Chang PT, Hsin LW, and Chern JW (2013) Quinazolin-4-one derivatives as selective histone deacetylase-6 inhibitors for the treatment of Alzheimer’s disease. J. Med. Chem 56, 6775–91. PubMed

Strebl MG, Campbell AJ, Zhao WN, Schroeder FA, Riley MM, Chindavong PS, Morin TM, Haggarty SJ, Wagner FF, Ritter T, and Hooker JM (2017) HDAC6 Brain Mapping with [(18)F]Bavarostat Enabled by a Ru-Mediated Deoxyfluorination. ACS Cent. Sci 3, 1006–14. PubMed PMC

Wager TT, Chandrasekaran RY, Hou X, Troutman MD, Verhoest PR, Villalobos A, and Will Y (2010) Defining desirable central nervous system drug space through the alignment of molecular properties, in vitro ADME, and safety attributes. ACS Chem. Neurosci 1, 420–34. PubMed PMC

Wager TT, Hou X, Verhoest PR, and Villalobos A (2010) Moving beyond rules: the development of a central nervous system multiparameter optimization (CNS MPO) approach to enable alignment of druglike properties. ACS Chem. Neurosci 1, 435–49. PubMed PMC

Wager TT, Hou X, Verhoest PR, and Villalobos A (2016) Central Nervous System Multiparameter Optimization Desirability: Application in Drug Discovery. ACS Chem. Neurosci 7, 767–75. PubMed

Porter NJ, Mahendran A, Breslow R, and Christianson DW (2017) Unusual zinc-binding mode of HDAC6-selective hydroxamate inhibitors. Proc. Natl. Acad. Sci. U. S. A 114, 13459–64. PubMed PMC

Wagner FF, Olson DE, Gale JP, Kaya T, Weiwer M, Aidoud N, Thomas M, Davoine EL, Lemercier BC, Zhang YL, and Holson EB (2013) Potent and selective inhibition of histone deacetylase 6 (HDAC6) does not require a surface-binding motif. J. Med. Chem 56, 1772–6. PubMed

Porter NJ, Wagner FF, and Christianson DW (2018) Entropy as a Driver of Selectivity for Inhibitor Binding to Histone Deacetylase 6. Biochemistry 57, 3916–24. PubMed PMC

Shen S, Benoy V, Bergman JA, Kalin JH, Frojuello M, Vistoli G, Haeck W, Van Den Bosch L, and Kozikowski AP (2016) Bicyclic-Capped Histone Deacetylase 6 Inhibitors with Improved Activity in a Model of Axonal Charcot-Marie-Tooth Disease. ACS Chem. Neurosci 7, 240–58. PubMed PMC

Gaisina IN, Lee SH, Kaidery NA, Ben Aissa M, Ahuja M, Smirnova NN, Wakade S, Gaisin A, Bourassa MW, Ratan RR, Nikulin SV, Poloznikov AA, Thomas B, Thatcher GRJ, and Gazaryan IG (2018) Activation of Nrf2 and Hypoxic Adaptive Response Contribute to Neuroprotection Elicited by Phenyl-hydroxamic Acid Selective HDAC6 Inhibitors. ACS Chem. Neurosci 9, 894–900. PubMed PMC

Bergman JA, Woan K, Perez-Villarroel P, Villagra A, Sotomayor EM, and Kozikowski AP (2012) Selective histone deacetylase 6 inhibitors bearing substituted urea linkers inhibit melanoma cell growth. J. Med. Chem 55, 9891–9. PubMed PMC

Robers MB, Dart ML, Woodroofe CC, Zimprich CA, Kirkland TA, Machleidt T, Kupcho KR, Levin S, Hartnett JR, Zimmerman K, Niles AL, Ohana RF, Daniels DL, Slater M, Wood MG, Cong M, Cheng YQ, and Wood KV (2015) Target engagement and drug residence time can be observed in living cells with BRET. Nat. Commun 6, 10091. PubMed PMC

Jin X, Luong TL, Reese N, Gaona H, Collazo-Velez V, Vuong C, Potter B, Sousa JC, Olmeda R, Li Q, Xie L, Zhang J, Zhang P, Reichard G, Melendez V, Marcsisin SR, and Pybus BS (2014) Comparison of MDCK-MDR1 and Caco-2 cell based permeability assays for anti-malarial drug screening and drug investigations. J. Pharmacol. Toxicol. Methods 70, 188–94. PubMed

Wang Q, Rager JD, Weinstein K, Kardos PS, Dobson GL, Li J, and Hidalgo IJ (2005) Evaluation of the MDR-MDCK cell line as a permeability screen for the blood-brain barrier. Int. J. Pharm 288, 349–59. PubMed

Ghose AK, Herbertz T, Hudkins RL, Dorsey BD, and Mallamo JP (2012) Knowledge-Based, Central Nervous System (CNS) Lead Selection and Lead Optimization for CNS Drug Discovery. ACS Chem. Neurosci 3, 50–68. PubMed PMC

Tam KY, Avdeef A, Tsinman O, and Sun N (2010) The permeation of amphoteric drugs through artificial membranes—an in combo absorption model based on paracellular and transmembrane permeability. J. Med. Chem 53, 392–401. PubMed

Wu YJ, Guernon J, McClure A, Luo G, Rajamani R, Ng A, Easton A, Newton A, Bourin C, Parker D, Mosure K, Barnaby O, Soars MG, Knox RJ, Matchett M, Pieschl R, Herrington J, Chen P, Sivarao DV, Bristow LJ, Meanwell NA, Bronson J, Olson R, Thompson LA, and Dzierba C (2017) Discovery of non-zwitterionic aryl sulfonamides as Nav1.7 inhibitors with efficacy in preclinical behavioral models and translational measures of nociceptive neuron activation. Bioorg. Med. Chem 25, 5490–505. PubMed

Hamdouchi C, Maiti P, Warshawsky AM, DeBaillie AC, Otto KA, Wilbur KL, Kahl SD, Patel Lewis A, Cardona GR, Zink RW, Chen K, Cr S, Lineswala JP, Neathery GL, Bouaichi C, Diseroad BA, Campbell AN, Sweetana SA, Adams LA, Cabrera O, Ma X, Yumibe NP, Montrose-Rafizadeh C, Chen Y, and Miller AR (2018) Discovery of LY3104607: A Potent and Selective G Protein-Coupled Receptor 40 (GPR40) Agonist with Optimized Pharmacokinetic Properties to Support Once Daily Oral Treatment in Patients with Type 2 Diabetes Mellitus. J. Med. Chem 61, 934–45. PubMed

Shen S, and Kozikowski AP (2016) Why Hydroxamates May Not Be the Best Histone Deacetylase Inhibitors—What Some May Have Forgotten or Would Rather Forget? ChemMedChem 11, 15–21. PubMed PMC

Pieretti M, Zhang FP, Fu YH, Warren ST, Oostra BA, Caskey CT, and Nelson DL (1991) Absence of expression of the FMR-1 gene in fragile X syndrome. Cell 66, 817–22. PubMed

The Dutch-Belgian Fragile X Consortium, Bakker CE, Verheij C, Willemsen R, et al. (1994) Fmr1 knockout mice: a model to study fragile X mental retardation. Cell 78, 23–33. PubMed

Franklin AV, King MK, Palomo V, Martinez A, McMahon LL, and Jope RS (2014) Glycogen synthase kinase-3 inhibitors reverse deficits in long-term potentiation and cognition in fragile X mice. Biol. Psychiatry 75, 198–206. PubMed PMC

Yuskaitis CJ, Mines MA, King MK, Sweatt JD, Miller CA, and Jope RS (2010) Lithium ameliorates altered glycogen synthase kinase-3 and behavior in a mouse model of fragile X syndrome. Biochem. Pharmacol 79, 632–46. PubMed PMC

Wang XX, Wan RZ, and Liu ZP (2018) Recent advances in the discovery of potent and selective HDAC6 inhibitors. Eur. J. Med. Chem 143, 1406–18. PubMed

Li L, and Yang XJ (2015) Tubulin acetylation: responsible enzymes, biological functions and human diseases. Cell. Mol. Life Sci 72, 4237–55. PubMed PMC

Taes I, Timmers M, Hersmus N, Bento-Abreu A, Van Den Bosch L, Van Damme P, Auwerx J, and Robberecht W (2013) Hdac6 deletion delays disease progression in the SOD1G93A mouse model of ALS. Hum. Mol. Genet 22, 1783–90. PubMed

Fernandez-Barrera J, Correas I, and Alonso MA (2018) Age-related neuropathies and tubulin acetylation. Aging 10, 524–25. PubMed PMC

Erck C, Peris L, Andrieux A, Meissirel C, Gruber AD, Vernet M, Schweitzer A, Saoudi Y, Pointu H, Bosc C, Salin PA, Job D, and Wehland J (2005) A vital role of tubulin-tyrosine-ligase for neuronal organization. Proc. Natl. Acad. Sci. U. S. A 102, 7853–8. PubMed PMC

Ventura R, Pascucci T, Catania MV, Musumeci SA, and Puglisi-Allegra S (2004) Object recognition impairment in Fmr1 knockout mice is reversed by amphetamine: involvement of dopamine in the medial prefrontal cortex. Behav. Pharmacol 15, 433–42. PubMed

Pacey LK, Tharmalingam S, and Hampson DR (2011) Subchronic administration and combination metabotropic glutamate and GABAB receptor drug therapy in fragile X syndrome. J. Pharmacol. Exp. Ther 338, 897–905. PubMed PMC

Eadie BD, Cushman J, Kannangara TS, Fanselow MS, and Christie BR (2012) NMDA receptor hypofunction in the dentate gyrus and impaired context discrimination in adult Fmr1 knockout mice. Hippocampus 22, 241–54. PubMed

King MK, and Jope RS (2013) Lithium treatment alleviates impaired cognition in a mouse model of fragile X syndrome. Genes Brain Behav 12, 723–31. PubMed PMC

Miyake Y, Keusch JJ, Wang L, Saito M, Hess D, Wang X, Melancon BJ, Helquist P, Gut H, and Matthias P (2016) Structural insights into HDAC6 tubulin deacetylation and its selective inhibition. Nat. Chem. Biol 12, 748–54. PubMed

Pardo M, King MK, Perez-Costas E, Melendez-Ferro M, Martinez A, Beurel E, and Jope RS (2015) Impairments in cognition and neural precursor cell proliferation in mice expressing constitutively active glycogen synthase kinase-3. Front. Behav. Neurosci 9, 55. PubMed PMC

Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem 72, 248–54. PubMed

Selectivity of Hydroxamate- and Difluoromethyloxadiazole-Based Inhibitors of Histone Deacetylase 6 In Vitro and in Cells

Structural and in Vivo Characterization of Tubastatin A, a Widely Used Histone Deacetylase 6 Inhibitor

The disordered N-terminus of HDAC6 is a microtubule-binding domain critical for efficient tubulin deacetylation