The Histone Deacetylase HDAC4 Connects Neural Activity to Muscle Transcriptional Reprogramming

Neural activity actively regulates muscle gene expression. This regulation is crucial for specifying muscle functionality and synaptic protein expression. How neural activity is relayed into nuclei and connected to the muscle transcriptional machinery, however, is not known. Here we identify the histone deacetylase HDAC4 as the critical linker connecting neural activity to muscle transcription. We found that HDAC4 is normally concentrated at the neuromuscular junction (NMJ), where nerve innervates muscle. Remarkably, reduced neural input by surgical denervation or neuromuscular diseases dissociates HDAC4 from the NMJ and dramatically induces its expression, leading to robust HDAC4 nuclear accumulation. We present evidence that nuclear accumulated HDAC4 is responsible for the coordinated induction of synaptic genes upon denervation. Inactivation of HDAC4 prevents denervation-induced synaptic acetyl-choline receptor (nAChR) and MUSK transcription whereas forced expression of HDAC4 mimics denervation and activates ectopic nAChR transcription throughout myofibers. We determined that HDAC4 executes activity-dependent transcription by regulating the Dach2-myogenin transcriptional cascade where inhibition of the repressor Dach2 by HDAC4 permits the induction of the transcription factor myogenin, which in turn activates synaptic gene expression. Our findings establish HDAC4 as a neural activity-regulated deacetylase and a key signaling component that relays neural activity to the muscle transcriptional machinery. Neural activity actively regulates muscle gene expression. This regulation is crucial for specifying muscle functionality and synaptic protein expression. How neural activity is relayed into nuclei and connected to the muscle transcriptional machinery, however, is not known. Here we identify the histone deacetylase HDAC4 as the critical linker connecting neural activity to muscle transcription. We found that HDAC4 is normally concentrated at the neuromuscular junction (NMJ), where nerve innervates muscle. Remarkably, reduced neural input by surgical denervation or neuromuscular diseases dissociates HDAC4 from the NMJ and dramatically induces its expression, leading to robust HDAC4 nuclear accumulation. We present evidence that nuclear accumulated HDAC4 is responsible for the coordinated induction of synaptic genes upon denervation. Inactivation of HDAC4 prevents denervation-induced synaptic acetyl-choline receptor (nAChR) and MUSK transcription whereas forced expression of HDAC4 mimics denervation and activates ectopic nAChR transcription throughout myofibers. We determined that HDAC4 executes activity-dependent transcription by regulating the Dach2-myogenin transcriptional cascade where inhibition of the repressor Dach2 by HDAC4 permits the induction of the transcription factor myogenin, which in turn activates synaptic gene expression. Our findings establish HDAC4 as a neural activity-regulated deacetylase and a key signaling component that relays neural activity to the muscle transcriptional machinery. The histone deacetylase HDAC4 and its closely related family member HDAC5 have been implicated in muscle differentiation by virtue of their efficient binding and inhibition of MEF2, a master transcription factor critical for muscle differentiation (1Bassel-Duby R. Olson E.N. Annu. Rev. Biochem. 2006; 75: 19-37Crossref PubMed Scopus (586) Google Scholar). The potent transcriptional repressor activity of HDAC4 and HDAC5, in turn, is negatively regulated by calcium/calmodulin-dependent kinase (CaMK) 3The abbreviations used are: CaMK, calcium/calmodulin-dependent kinase; GFP, green fluorescent protein; FITC, fluorescein isothiocyanate; nAChR, nicotinic acetylcholine receptors; NMJ, neuromuscular junction; MGN, myogenin; wt, wild type. 3The abbreviations used are: CaMK, calcium/calmodulin-dependent kinase; GFP, green fluorescent protein; FITC, fluorescein isothiocyanate; nAChR, nicotinic acetylcholine receptors; NMJ, neuromuscular junction; MGN, myogenin; wt, wild type. (2McKinsey T.A. Zhang C.L. Lu J. Olson E.N. Nature. 2000; 408: 106-111Crossref PubMed Scopus (860) Google Scholar, 3Zhao 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 (114) Google Scholar). CaMK-mediated phosphorylation promotes 14-3-3 association and nuclear export of HDAC4 and HDAC5, resulting in MEF2 activation. The active intracellular trafficking of HDAC4 and related class IIA HDACs was considered a key regulatory mechanism for MEF2 transcriptional activity. As potent repressors of MEF2, HDAC4 and HDAC5 were logically proposed to act as inhibitors of skeletal muscle differentiation, and their nuclear exclusion induced by CaMK was thought to allow differentiation to proceed (2McKinsey T.A. Zhang C.L. Lu J. Olson E.N. Nature. 2000; 408: 106-111Crossref PubMed Scopus (860) Google Scholar). Surprisingly, our previous analysis, however, showed that HDAC4 became concentrated to rather than excluded from the nuclei upon C2C12 myotube formation (3Zhao 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 (114) Google Scholar). This unexpected finding is incompatible with a simple model that nuclear HDAC4 prevents muscle differentiation. Instead, the import of HDAC4 into nuclei of myotubes likely reflects a specific function of HDAC4 in the differentiated myofiber. However, any potential role for HDAC4 in the regulation of muscle function in vivo has not been established. Muscle can undergo remodeling to meet changing functional demands. This remodeling is largely accomplished by specific transcriptional reprogramming induced by neural activity (1Bassel-Duby R. Olson E.N. Annu. Rev. Biochem. 2006; 75: 19-37Crossref PubMed Scopus (586) Google Scholar). The intimate relationship between neural activity and muscle gene transcription is best illustrated by the dynamic regulation of synaptic gene expression. The expression of synaptic proteins, such as nicotinic acetylcholine receptors (nAChRs), are exquisitely sensitive to innervation status (reviewed in Ref. 4Sanes J.R. Lichtman J.W. Nat. Rev Neurosci. 2001; 2: 791-805Crossref PubMed Scopus (793) Google Scholar). During embryonic development before muscles are innervated, nAChRs are expressed throughout muscle fibers. This high level of nAChRs confers acetylcholine supersensitivity and may be important for the subsequent formation of synaptic structures upon innervation. After innervation, a dramatic repression of nAChR expression occurs throughout muscle except for a small number of nuclei adjacent to the neuromuscular junction (NMJ), the site of nerve-muscle communication. This active repression of “extra-synaptic” transcription contributes to the high concentration of nAChR at the NMJ, a spatial organization that is critical for efficient propagation of electrical signals from motor neurons. Remarkably, this repression can be readily reversed upon denervation, leading to rapid induction of nAChR and other synaptic genes (5Neville C. Schmidt M. Schmidt J. Neuroreport. 1991; 2: 655-657Crossref PubMed Scopus (11) Google Scholar). The tight regulation of nAChR expression illustrates the dominant effect of neural activity on muscle gene transcription and function. The critical issue of how neural signals originating at the NMJ are relayed to the transcriptional machinery in the nucleus remains poorly understood. The bHLH transcription factor myogenin (MGN) is a critical regulator for nAChR expression. MGN binds and activates E-box elements (CANNTG) present in the promoters of activity-regulated synaptic genes including nAChRϵ, nAChRδ, and MUSK (6Bessereau J.L. Stratford-Perricaudet L.D. Piette J. Le Poupon C. Changeux J.P. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: 1304-1308Crossref PubMed Scopus (71) Google Scholar, 7Merlie J.P. Mudd J. Cheng T.C. Olson E.N. J. Biol. Chem. 1994; 269: 2461-2467Abstract Full Text PDF PubMed Google Scholar). In normal innervated muscle, myogenin transcription is repressed, ensuring low expression of nAChR in extra-synaptic nuclei. Upon surgical denervation, MGN becomes induced, resulting in the expression of nAChR and other NMJ components (5Neville C. Schmidt M. Schmidt J. Neuroreport. 1991; 2: 655-657Crossref PubMed Scopus (11) Google Scholar). Thus, myogenin expression is central to activity-regulated synaptic gene expression. Myogenin expression appears to be regulated by at least two mechanisms. HDAC9 (MITR) is thought to repress myogenin expression through inhibition of MEF2 (20Mejat A. Ramond F. Bassel-Duby R. Khochbin S. Olson E.N. Schaeffer L. Nat. Neurosci. 2005; 8: 313-321Crossref PubMed Scopus (138) Google Scholar). More recently, a Dachschund related transcriptional co-repressor, Dach2, was reported to inhibit myogenin expression in innervated muscle (8Tang H. Goldman D. Proc. Natl. Acad. Sci. U. S. A. 2006; 103: 16977-16982Crossref PubMed Scopus (58) Google Scholar). Interestingly, Dach2 expression itself is suppressed by denervation, suggesting a model whereby reduction of Dach2 leads to transcriptional induction of myogenin and subsequent activation of nAChR in extrasynaptic myofibers (8Tang H. Goldman D. Proc. Natl. Acad. Sci. U. S. A. 2006; 103: 16977-16982Crossref PubMed Scopus (58) Google Scholar). How neural activity is connected to the nuclear Dach2/myogenin transcriptional cascade, however, is not known. Here we present evidence that HDAC4 is a critical component that relays neural input into the nucleus for the regulation of Dach2, myogenin, and nAChR gene expression. In innervated muscle, we found that HDAC4 is expressed at low levels and concentrated at the NMJ, where it co-localizes with CaMKIIδ and 14-3-3 proteins. Importantly, upon reduced neural activity by surgical denervation or defects associated with neuromuscular disease, HDAC4 dissociates from the NMJ, becomes transcriptionally induced and accumulates in nuclei. Thus, HDAC4 levels and subcellular localization are tightly controlled by neural activity. Supporting a critical role for HDAC4 in relaying neural activity into muscle nuclei, we showed that HDAC4 is required for the active repression of Dach2 and the induction of nAChR in response to denervation. Conversely, elevated HDAC4 levels mimic the effect of denervation and induce ectopic nAChR throughout myofibers. We propose that HDAC4 is a critical link between neural activity and muscle gene expression that enables muscle remodeling in response to changing neural input. Plasmids and Antibodies—HDAC4wt and HDAC4-3SA DNA fragments containing 5′ EcoRI and 3′ SmaI sites were cloned into the RI/SmaI site on the vector GFP-expressing plasmid, pEGFP-C1, to generate N-terminal GFP-tagged HDAC4wt and HDAC4-3SA mutant used in Fig. 4 electroporation experiments. HDAC4 polyclonal antibody (clone 186) was previously described (3Zhao 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 (114) Google Scholar). P-HDAC4-S467 antibody was generated by Pocono Rabbit Farm using the following peptide against human HDAC4-S467: NH2-CRQHRPLGRTQSAP-LPQN-COOH phosphorylated on serine residue. Antibody was affinity purified and specificity was confirmed (see supplemental Figs. S1 and S2). 14-3-3 and CAMKIIδ antibodies are from Santa Cruz Biotechnology. Mouse Procedures—6-week-old C57/BL mice (Jackson Laboratories) were anesthetized with a ketamine/xylazine mixture (25 mg/ml ketamine, 1 mg/ml xylazine in 0.9% NaCl; 100 μl used per mouse. Hair was removed from area surrounding muscle. For denervation, sciatic nerve was exposed and ∼5-mm piece of nerve was cut and removed. Incision was sutured, and mice were allowed to recover. For overexpression electroporation analysis, 25 μg of GFP, HDAC4-GFP, or HDAC4-3SA-GFP was used for injection. For siRNA experiments, 500 pmol of siRNA oligo was used per injection. DNA or siRNA were directly injected into TA muscles using cemented MicroSyringe (VWR). ECM 830 electroporator (BTX) was used for all electroporations. Tweezertrodes (Model 520) were coated with transmission gel and were placed outside the skin around the muscle belly and pulsed 5 times at 50 V, 60-ms duration, with 200-ms interval time. Mice were allowed to recover in their cages. Stealth siRNA duplexed oligos are from Invitrogen. Sequences are as follows: mouse HDAC4: 5′-CACCGGAACCUGAACCACUGCAUUU-3′, mouse HDAC5: 5′-GGUCCUCAUCGUGGACUGGGAUAUU-3′. All mice were housed at the Duke University mouse facilities in accordance with the Institutional Animal Care and Use Committee. Western Analysis—Tibialis muscles were isolated and frozen in liquid nitrogen. Muscles were Dounce-homogenized on ice using 1 ml of glass-on-glass homogenizers and grinded in radio-immune precipitation assay buffer (0.05 m NaCl, 0.02 m Tris, pH 7.6, 1 mm EDTA, supplemented with leupeptin, and 1 mm were with for of at and at for to was using the assay The HDAC4 polyclonal antibody was used as described previously T.A. Yao T.P. J. Neurosci. 2005; PubMed Scopus Google Scholar). antibody was For HDAC4 50 μg of protein was and HDAC4 antibody was analysis, TA muscles were Dounce-homogenized in 1 ml of and at μl of was and were at for was to 500 μl of and at for was with and in for For μg of was on a was and using fragments of HDAC4 or generated from were exposed for at For analysis, was using and 1 μg was used for using were and 5 μl of was used per was using green on the was μl per and specificity of were confirmed by and DNA on was All were to or as All were confirmed with In vivo overexpression are on to which is to 1 the all a with fibers. are as follows: HDAC4: HDAC5: HDAC9 muscle were and placed in containing (VWR). or were using a at C. were at For were for in at After in 5 were in for and with antibody are as follows: HDAC4 (clone 186) (clone 14-3-3 Santa Cruz CAMKIIδ Santa Cruz were in 5 in and in antibody for with or as antibodies used were from and and or was used were in for All were with a with a or Muscle HDAC4 in to and with HDAC4 as of the induced genes in muscle to (see S1 in Ref. S. L. 2001; PubMed Scopus Google Scholar). As a reduction in neuromuscular we HDAC4 is regulated by neural activity in skeletal muscle. a mouse denervation model of was mice were for and muscles were to Western with As in Fig. HDAC4 protein is dramatically in muscle with the The induction of HDAC4 occurs denervation and appears to be by that HDAC4 protein is and induced in response to denervation. induction of HDAC4 occurs at the protein level or transcription from and muscle was by and As in Fig. showed that denervation a dramatic induction of the HDAC4 a transcriptional of regulation on HDAC4 HDAC4 to the that HDAC4 levels are induced by than (see Fig. Interestingly, HDAC5 is induced by denervation, and HDAC9 levels are not or that HDAC4 may be a of a muscle transcriptional in response to neural activity by denervation is a of neuromuscular HDAC4 is in skeletal muscle associated with neuromuscular disease, we HDAC4 levels in two of muscle mice and mice C.L. Full Text Full Text PDF PubMed Scopus Google Scholar, T.P. S.M. PubMed Scopus Google Scholar). As in Fig. HDAC4 is dramatically induced in skeletal muscle from and Interestingly, at was motor HDAC4 was induced in muscle not in the muscle. This finding is in with previous that in mice are sensitive to than connecting HDAC4 induction to neuromuscular In by in the and by in the S.M. 2006; PubMed Scopus Google which are in the of neuromuscular showed of HDAC4 HDAC4 is induced in response to neural as to muscle HDAC4 in to class IIA HDACs have been to between the nucleus and the we determined the subcellular localization of HDAC4 is regulated by neural activity and by denervation. muscle were from and muscle, and was using a specific HDAC4 As in Fig. muscles with nuclear suggesting a level of nuclear HDAC4 normal Remarkably, a dramatic of HDAC4 is in in muscle to denervation This finding that HDAC4 becomes accumulated in the nucleus in response to During the of HDAC4 subcellular localization in we structures that for with which binds the nAChR, that structures are neuromuscular sites where nerve activity is Interestingly, the NMJ is using a antibody that HDAC4 phosphorylated on serine a site The NMJ is in the of antibody specificity (see supplemental Figs. S1 and S2). As binds and HDAC4 and is the that neural we determined is a component of the as in Fig. we found that the CaMKIIδ and 14-3-3 are concentrated at the NMJ, that HDAC4 and its are to the electrical activity is by L. Goldman D. J. PubMed Scopus Google Scholar, Schmidt J. 1994; PubMed Scopus Google Scholar, A. Changeux J.P. Proc. Natl. Acad. Sci. U. S. A. PubMed Google we that HDAC4 be controlled by in by neural activity. We determined HDAC4 localization to the NMJ is regulated by nerve activity. As in Fig. a denervation induced a rapid of HDAC4 from the NMJ, CaMKIIδ localization to the NMJ largely not two of regulation on HDAC4 in response to nerve the activity-dependent localization of HDAC4 to the NMJ as a potential of nerve and the transcriptional induction and nuclear of HDAC4 in response to HDAC4 for Dach2, MGN, and nAChR that a transcription nuclear upon of nerve activity. are with the proposed factor that neural activity to muscle transcription. We HDAC4 is required for the transcriptional regulation of the cascade in response to denervation. we determined the of HDAC4 induction in to Dach2, MGN, and nAChR gene expression, a in response to denervation. Mice were and muscles were at for As in Fig. HDAC4 levels by at at which Dach2 levels to MGN and nAChR levels to around This that the induction of HDAC4 with the repression of Dach2, and that this regulation may required for the subsequent induction of including We determined HDAC4 regulates Dach2 expression. this GFP, HDAC4 and the nuclear were into mouse muscle (see Fig. for and were and by As in Fig. and the HDAC4-3SA mutant were of Dach2 levels in this Dach2 is by with this mutant HDAC4 and HDAC4-3SA expression to induction of MGN, nAChR, and MUSK with fibers. We that HDAC4-3SA mutant is not active than HDAC4 in this This be by its expression (see Fig. of the associated with nuclear class IIA HDACs J. Olson E.N. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). that elevated levels of HDAC4 are to repress Dach2 and induce synaptic gene expression, the effect of denervation. the of HDAC4 in the activity-dependent transcriptional cascade, in vivo was using siRNA (see Fig. siRNA or HDAC4 siRNA was into mouse muscle, and electroporation mice were for by As previously reported (8Tang H. Goldman D. Proc. Natl. Acad. Sci. U. S. A. 2006; 103: 16977-16982Crossref PubMed Scopus (58) Google and as in Fig. and Dach2 levels are reduced denervation with a induction of the activity-dependent genes MGN, nAChR, and Importantly, of HDAC4 the repression of Dach2 that occurs denervation. with this the induction of MGN, nAChR, and MUSK are all in muscles with HDAC4 siRNA (see Fig. Interestingly, siRNA of HDAC4 and HDAC5 a to that of the HDAC4 a critical role for HDAC4 in the regulation of this that HDAC4 is required for activity-dependent induction of synaptic gene expression, and that HDAC4 this effect through of the myogenin HDAC4 nAChR in nAChR levels are elevated and the of the muscle outside the the of HDAC4 in activity-regulated nAChR expression, we the localization of nAChR in and HDAC4 siRNA muscle before and denervation. the of we a GFP-expressing with or HDAC4 siRNA As in Fig. 5 muscle not any nAChR, with the of nAChR in extrasynaptic muscle. In muscle the siRNA showed a dramatic induction of nAChR with the of extrasynaptic nAChR in response to (see Fig. Remarkably, the of nAChR is in HDAC4 myofibers that HDAC4 is required for extrasynaptic nAChR expression in response to denervation. Neural activity-regulated gene expression is crucial for specifying muscle a coordinated remodeling that confers muscles to to demands. the that neural activity to nuclear gene expression is critical issue in muscle In this we evidence that the histone deacetylase HDAC4 is that neural activity to muscle transcriptional machinery important for synaptic protein gene expression. The localization to the NMJ HDAC4 in to where neural activity is and in muscle. we showed that HDAC4 levels and subcellular localization are regulated by neural activity. The of HDAC4 in activity-dependent gene expression is by its for the repression of Dach2 and the subsequent induction of MGN, nAChR, and MUSK transcription upon denervation. findings establish HDAC4 as a signaling component critical for the of activity-regulated gene expression and a to how neural activity is relayed into the nucleus to muscle transcription HDAC4 and Muscle gene transcription skeletal muscle the functional for changing demands. The that relays neural activity into muscle nuclei, is a crucial component that the of nerve activity and muscle our found that a potent MEF2 repressor thought to inhibit muscle differentiation, a critical role in connecting neural activity to muscle gene expression. This finding that HDAC4 not act to inhibit skeletal muscle differentiation the function of and the related HDAC5 and is to muscle transcription that muscle can specific functionality by neural Our evidence that key function of HDAC4 in skeletal muscle is to synaptic gene expression in response to neural activity. Our that HDAC4 is required for the robust transcriptional induction of the synaptic genes nAChR and MUSK by denervation and In ectopic expression of HDAC4 is to mimic denervation and induce expression of MGN, nAChR, and MUSK In this regulatory we Dach2 as critical transcriptional of We showed that repression of Dach2 transcription with the induction of a of Dach2 expression by HDAC4 This is with that transcriptional repression of Dach2 required activity (8Tang H. Goldman D. Proc. Natl. Acad. Sci. U. S. A. 2006; 103: 16977-16982Crossref PubMed Scopus (58) Google Scholar). the specific mechanism by which HDAC4 Dach2 expression remains to be this regulation is likely a as assay that HDAC4 with the of J. our showed that HDAC4 induced by denervation is required for the transcriptional repression of The repression of Dach2 by HDAC4 the induction of MGN, which in turn activates nAChR and other genes responsible for NMJ formation D. Goldman D. Neurosci. 2006; PubMed Scopus Google Scholar). with a role for HDAC4 in synaptic gene expression, we have expression of HDAC4 in nuclei in innervated muscle (see supplemental Fig. establish HDAC4 as a key for neural activity-regulated synaptic gene expression. Our that activity-dependent muscle gene transcription a regulation of HDAC4 subcellular localization and In innervated muscle, we found that HDAC4 and are present at the NMJ, where neural activity in muscle. Interestingly, it was reported that not the closely related HDAC5, binds active J. S. S. Olson E.N. J. 2006; PubMed Scopus Google Scholar). sensitive to H. PubMed Scopus Google is a in neural activity on The of HDAC4 and at the NMJ model whereby HDAC4 and to activity at the NMJ by virtue of its functional with (see Fig. Upon reduced neural HDAC4 dissociates from the NMJ and accumulates in the nucleus where it induces specific transcriptional neural activity and muscle gene transcription. In this the localization as as the levels of HDAC4 may the muscle transcriptional on neural input. IIA HDACs and a More to our that HDAC5 is induced in response to denervation. Importantly, muscle with HDAC4 or showed defects in myogenin or nAChR expression (see Fig. and suggesting that HDAC4 a dominant role in synaptic gene expression in this The dramatic induction of HDAC4 in however, is in to the repression of the of HDAC9 the (20Mejat A. Ramond F. Bassel-Duby R. Khochbin S. Olson E.N. Schaeffer L. Nat. Neurosci. 2005; 8: 313-321Crossref PubMed Scopus (138) Google Scholar). (20Mejat A. Ramond F. Bassel-Duby R. Khochbin S. Olson E.N. Schaeffer L. Nat. Neurosci. 2005; 8: 313-321Crossref PubMed Scopus (138) Google previously showed that as a myogenin and that denervation leads to repression and subsequent activation of our confirmed a reduction of HDAC9 expression in muscle findings are as HDAC9 (MITR) and HDAC4 repress MEF2 are regulated by neural activity. HDAC4 and muscle have effect on MGN expression and Ref. A. Ramond F. Bassel-Duby R. Khochbin S. Olson E.N. Schaeffer L. Nat. Neurosci. 2005; 8: 313-321Crossref PubMed Scopus (138) Google Scholar). More be required to how the reduction of and the induction of HDAC4 to denervation-induced nAChR expression. however, are with the of and regulation of nAChR as reported by and Goldman (8Tang H. Goldman D. Proc. Natl. Acad. Sci. U. S. A. 2006; 103: 16977-16982Crossref PubMed Scopus (58) Google Scholar). Our that the sensitive is by Dach2 repression whereas the is controlled by findings important role for class IIA HDACs in activity-dependent muscle gene transcription. HDAC4 and have found that HDAC4 levels are dramatically induced in muscles of and neuromuscular This finding that HDAC4 be in the development of muscle associated with or other neuromuscular inhibition of HDAC4 by specific inhibitors potential to neuromuscular In this has been to the in the mouse model H. J. F. J. 2005; PubMed Scopus Google Scholar). Our that HDAC4 be a key for the of Neural activity-dependent muscle remodeling a critical role for skeletal muscle to to functional by changing specific transcription important for nAChR expression, gene expression and Our HDAC4 as a key that the activity-dependent The of HDAC4 in other of muscle remodeling HDAC4 is a master regulator of muscle functionality controlled by neural activity. We for HDAC4 polyclonal We Olson for We and for on the We and for and antibody We for and with