Histone deacetylase 5 deacetylates the phosphatase PP2A for positively regulating NF-κB signaling

Abstract

Histone deacetylase 5 (HDAC5) has been reported to have a strong regulatory function in the proinflammatory response, but the mechanism is still unknown. Here, we identified HDAC5 as a positive regulator of NF-κB signaling in vivo. HDAC5-deficient mice exhibited enhanced survival in response to LPS challenge. Using LPS, TNFα, different kinds of viruses, hydrogen peroxide, or ultraviolet stimulation, we demonstrate that HDAC5-mediated regulation of NF-κB occurs in manners both dependent on and independent of IKK, an upstream kinase in the NF-κB signaling pathway. Deficiency in HDAC5 impaired the phosphorylation of IKKβ, subsequent phosphorylation of the NF-κB inhibitor protein IκBα and NF-κB subunit p65. We also show that the phosphatase PP2A repressed transcriptional activation of NF-κB by decreasing phosphorylation of IKKβ, p65, and IκBα. In vitro deacetylation experiments and site-directed mutagenesis experiments indicated that HDAC5 directly deacetylated PP2Ac at Lys136, which resulted in the deactivation of PP2A. Our data add mechanistic insight into the cross talk between epigenetic and posttranslational modifications regulating NF-κB signaling and protein phosphatase activation that mediate survival in response to inflammatory challenges. Histone deacetylase 5 (HDAC5) has been reported to have a strong regulatory function in the proinflammatory response, but the mechanism is still unknown. Here, we identified HDAC5 as a positive regulator of NF-κB signaling in vivo. HDAC5-deficient mice exhibited enhanced survival in response to LPS challenge. Using LPS, TNFα, different kinds of viruses, hydrogen peroxide, or ultraviolet stimulation, we demonstrate that HDAC5-mediated regulation of NF-κB occurs in manners both dependent on and independent of IKK, an upstream kinase in the NF-κB signaling pathway. Deficiency in HDAC5 impaired the phosphorylation of IKKβ, subsequent phosphorylation of the NF-κB inhibitor protein IκBα and NF-κB subunit p65. We also show that the phosphatase PP2A repressed transcriptional activation of NF-κB by decreasing phosphorylation of IKKβ, p65, and IκBα. In vitro deacetylation experiments and site-directed mutagenesis experiments indicated that HDAC5 directly deacetylated PP2Ac at Lys136, which resulted in the deactivation of PP2A. Our data add mechanistic insight into the cross talk between epigenetic and posttranslational modifications regulating NF-κB signaling and protein phosphatase activation that mediate survival in response to inflammatory challenges. Histone deacetylases (HDACs) can regulate gene expression via translational modification. HDACs are evolutionarily highly conserved proteins and have emerged as crucial transcriptional corepressors in highly diverse biological systems. Mammalian HDACs have been classified into four classes based on the homology of their catalytic domains, and the class II HDACs are further subdivided into two subclasses, classes IIa (HDAC4, 5, 7, and 9) and IIb (HDAC6 and 10) (1Martin M. Kettmann R. Dequiedt F. Class IIa histone deacetylases: Conducting development and differentiation.Int. J. Dev. Biol. 2009; 53: 291-301Crossref PubMed Scopus (52) Google Scholar). Some classical HDACs have been attributed key roles in immunity and inflammation (2Shakespear M.R. Halili M.A. Irvine K.M. Fairlie D.P. Sweet M.J. Histone deacetylases as regulators of inflammation and immunity.Trends Immunol. 2011; 32: 335-343Abstract Full Text Full Text PDF PubMed Scopus (352) Google Scholar). It has been reported that HDAC5 promotes inflammatory response through NF-κB activation (3Zhao Y. Ma G. Yang X. HDAC5 promotes Mycoplasma pneumoniae-induced inflammation in macrophages through NF-kappaB activation.Life Sci. 2019; 221: 13-19Crossref PubMed Scopus (12) Google Scholar, 4Poralla L. Stroh T. Erben U. Sittig M. Liebig S. Siegmund B. Glauben R. Histone deacetylase 5 regulates the inflammatory response of macrophages.J. Cell Mol. Med. 2015; 19: 2162-2171Crossref PubMed Scopus (36) Google Scholar), but the mechanism is unclear. NF-κB is a critical regulator of diverse cytokine-mediated cellular responses and regulates cell survival, proliferation, apoptosis, and immune responses (5Ghosh S. Hayden M.S. New regulators of NF-kappaB in inflammation.Nat. Rev. Immunol. 2008; 8: 837-848Crossref PubMed Scopus (1004) Google Scholar, 6Kondylis V. Kumari S. Vlantis K. Pasparakis M. The interplay of IKK, NF-kappaB and RIPK1 signaling in the regulation of cell death, tissue homeostasis and inflammation.Immunol. Rev. 2017; 277: 113-127Crossref PubMed Scopus (104) Google Scholar). Normally, NF-κB proteins are inactive, binding to the IκB family. Extracellular stimuli, such as tumor necrosis factor (TNF), interleukin 1 (IL-1), and toll-like receptor (TLR) ligands (7Heyninck K. Beyaert R. Crosstalk between NF-kappaB-activating and apoptosis-inducing proteins of the TNF-receptor complex.Mol. Cell Biol. Res. Commun. 2001; 4: 259-265Crossref PubMed Scopus (76) Google Scholar, 8Zhang G. Ghosh S. Toll-like receptor-mediated NF-kappaB activation: A phylogenetically conserved paradigm in innate immunity.J. Clin. Invest. 2001; 107: 13-19Crossref PubMed Scopus (592) Google Scholar), lead to the phosphorylation and degradation of IκB proteins and also the modifications of NF-κB subunits. The phosphorylation of NF-κB transcription factors was regulated not only by protein serine/threonine kinases but also by protein serine/threonine phosphatases. It had been reported the protein phosphatases (PPs) could regulate the NF-κB activation (9Li H.Y. Liu H. Wang C.H. Zhang J.Y. Man J.H. Gao Y.F. Zhang P.J. Li W.H. Zhao J. Pan X. Zhou T. Gong W.L. Li A.L. Zhang X.M. Deactivation of the kinase IKK by CUEDC2 through recruitment of the phosphatase PP1.Nat. Immunol. 2008; 9: 533-541Crossref PubMed Scopus (116) Google Scholar, 10Chew J. Biswas S. Shreeram S. Humaidi M. Wong E.T. Dhillion M.K. Teo H. Hazra A. Fang C.C. Lopez-Collazo E. Bulavin D.V. Tergaonkar V. WIP1 phosphatase is a negative regulator of NF-kappaB signalling.Nat. Cell Biol. 2009; 11: 659-666Crossref PubMed Scopus (126) Google Scholar). The predominant form of PP2A is a heterotrimeric holoenzyme. In the trimeric forms, the core enzyme component is the 36-kDa catalytic subunit (PP2Ac). A 65-kDa regulatory subunit is PP2Aa. PP2Ab could bind to the core enzyme (PP2Ac) and confer substrate specificity to its dephosphorylating activity (11Mumby M.C. Walter G. Protein serine/threonine phosphatases: Structure, regulation, and functions in cell growth.Physiol. Rev. 1993; 73: 673-699Crossref PubMed Scopus (623) Google Scholar). Treatment with okadaic acid (OA), a specific inhibitor of PP1 and PP2A, induces translocation of NF-κB to the nucleus and activation of NF-κB (12Thevenin C. Kim S.J. Rieckmann P. Fujiki H. Norcross M.A. Sporn M.B. Fauci A.S. Kehrl J.H. Induction of nuclear factor-kappa B and the human immunodeficiency virus long terminal repeat by okadaic acid, a specific inhibitor of phosphatases 1 and 2A.New Biol. 1990; 2: 793-800PubMed Google Scholar). PP2A could dephosphorylate p65 to reduce NF-κB activity (13Yang J. Fan G.H. Wadzinski B.E. Sakurai H. Richmond A. Protein phosphatase 2A interacts with and directly dephosphorylates RelA.J. Biol. Chem. 2001; 276: 47828-47833Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar, 14Hsieh C.Y. Hsu M.J. Hsiao G. Wang Y.H. Huang C.W. Chen S.W. Jayakumar T. Chiu P.T. Chiu Y.H. Sheu J.R. Andrographolide enhances nuclear factor-kappaB subunit p65 Ser536 dephosphorylation through activation of protein phosphatase 2A in vascular smooth muscle cells.J. Biol. Chem. 2011; 286: 5942-5955Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). Whether a host factor regulates the function of PP2A remains an open question. Here, we describe that HDAC5 regulates the phosphorylation of IKKβ and p65 by deacetylating and inactivating PP2A. HDAC5 promotes NF-κB activation in a deacetylation-dependent manner. HDAC5 deficiency suppresses the production of cytokines, such as TNF, both in vitro and in vivo. HDAC5 contributes to persistent phosphorylation of IKK, p65, and IκBα by disrupting the phosphatase PP2A activity. The acetylation of PP2Ac at Lys136 is crucial for its phosphatase activity. These results provide insights into the posttranslational modification involved in PP2A activity and established a novel function of HDAC5 as a key protein in the positive feedback mechanism to constitutively maintain NF-κB in an active state during stimulation. In our previous work, we found that HDAC3 and HDAC4 could functionally regulate type I interferon and inflammatory signaling pathway (15Tang J.L. Yang Q. Xu C.H. Zhao H. Liu Y.L. Liu C.Y. Zhou Y. Gai D.W. Pei R.J. Wang Y. Hu X. Zhong B. Wang Y.Y. Chen X.W. Chen J.Z. Histone deacetylase 3 promotes innate antiviral immunity through deacetylation of TBK1.Protein Cell. 2021; 12: 261-278Crossref PubMed Scopus (10) Google Scholar, 16Yang Q. Tang J. Xu C. Zhao H. Zhou Y. Wang Y. Yang M. Chen X. Chen J. Histone deacetylase 4 inhibits NF-kappaB activation by facilitating IkappaBalpha sumoylation.J. Mol. Cell Biol. 2020; 12: 933-945Crossref PubMed Scopus (3) Google Scholar, 17Yang Q. Tang J. Pei R. Gao X. Guo J. Xu C. Wang Y. Wang Q. Wu C. Zhou Y. Hu X. Zhao H. Wang Y. Chen X. Chen J. Host HDAC4 regulates the antiviral response by inhibiting the phosphorylation of IRF3.J. Mol. Cell Biol. 2019; 11: 158-169Crossref PubMed Scopus (14) Google Scholar). We further explored the role of other members of the HDAC family in innate immune signaling pathways. Knockdown of endogenous HDAC5 via shRNA in HEK293T reduced the SeV, IL-1β or TNFα-triggered activation of NF-κB in reporter assays (Fig. 1A). However, knockdown of HDAC5 did not affect the IFNγ-triggered IRF1 promoter activity (Fig. S1A). The production of TNFα or IL-6 in the HDAC5-deficient THP-1 cells or BMDMs was significantly lower compared with the control cells during LPS challenge (Fig. 1, B and C). When we expressed the HDAC5 in the HDAC5 knockdown HEK293T cells, the supplemental HDAC5 could rescue NF-κB reporter's depreciation (Fig. 1D) and the mRNA levels of TNFα, IL-6, and CXCL-10 (Fig. S1B) after TNFα treatment. Collectively, these data suggested that deficiency of HDAC5 negatively regulated NF-κB signaling. To confirm the contribution of HDAC5 to inflammatory responses, we stimulated HDAC5-overexpressing HEK293T cells with SeV or TNFα. The promoter activity of NF-κB was significantly higher when HDAC5 was overexpressed compared with samples transfected with the empty vector or the HDAC5 deacetylase partial inactive mutant (decreased by T. M. HDAC5 catalytic activity suppresses and gene Biol. Chem. 2019; Full Text Full Text PDF PubMed Scopus Google (Fig. of HDAC5 did not affect IFNγ-triggered IRF1 promoter activity (Fig. The production of TNFα or IL-6 was higher in HDAC5-overexpressing THP-1 cells after stimulated with LPS (Fig. we HDAC5 that to the and nucleus and The promoter activity of NF-κB was enhanced with the expression of HDAC5 or HDAC5 but not the nuclear HDAC5 (Fig. The TNFα could the HDAC5 deacetylase activity in a (Fig. These results suggested that the deacetylation activity and of HDAC5 positive roles in regulating inflammatory signaling. To further the of HDAC5 in inflammation in we a to mice which of HDAC5 in cells via expressed the gene We these mice with LPS and found that was lower that of the (Fig. mice TNFα or IL-6 in response to LPS (Fig. The of TNFα or IL-6 BMDMs mice was impaired compared with the BMDMs stimulated by SeV, or LPS (Fig. HDAC5 was for the production of inflammatory To the mechanism by which HDAC5 regulates inflammatory we the of HDAC5 knockdown on NF-κB activation by Knockdown of HDAC5 significantly NF-κB reporter activity by upstream and IKKβ, but not p65 (Fig. These results indicated that HDAC5 p65 The phosphorylation of p65 at Ser536 to the nucleus and the activity. The nuclear of p65 was lower in samples to control samples during SeV in HEK293T The data that the significantly p65 to to the nucleus in THP-1 cells during LPS (Fig. A and In cell or the levels of p65 by TNFα or LPS significantly impaired HDAC5 (Fig. A and The responses in the signaling of different cells with to HDAC5 regulates inflammatory signaling. In HEK293T cells, the phosphorylation of p65, and IκBα was reduced after SeV or TNFα (Fig. B and C). was also in the THP-1 cells during the LPS challenge (Fig. phosphorylation of p65, and IκBα in the BMDMs was significantly reduced in the control during SeV, or LPS challenge (Fig. It had been reported that the IKKβ could the IκBα and p65 H. H. H. T. kinases NF-kappaB p65 subunit on in the Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). These data suggested that HDAC5 could regulate the NF-κB NF-κB could through such as with hydrogen or ultraviolet K. M. S. P. and activation of NF-kappaB by J. PubMed Scopus Google Scholar), we knockdown HDAC5 NF-κB activation by or Knockdown of HDAC5 in HEK293T cells the IκBα degradation and the p65 phosphorylation at Ser536 (Fig. These results that HDAC5 could affect and NF-κB we the activity in regulating NF-κB HDAC5 did not affect the acetylation of p65 at (Fig. A and HDAC5 had on the between the signaling pathway (Fig. The in vitro IKK kinase indicated that HDAC5 did not directly regulate the kinase activity of or IKKβ (Fig. The phosphorylation was regulated by protein serine/threonine kinases and protein serine/threonine phosphatases. It has been reported that the and could the activation of NF-κB signaling by decreasing phosphorylation of IKKβ (9Li H.Y. Liu H. Wang C.H. Zhang J.Y. Man J.H. Gao Y.F. Zhang P.J. Li W.H. Zhao J. Pan X. Zhou T. Gong W.L. Li A.L. Zhang X.M. Deactivation of the kinase IKK by CUEDC2 through recruitment of the phosphatase PP1.Nat. Immunol. 2008; 9: 533-541Crossref PubMed Scopus (116) Google Scholar, 10Chew J. Biswas S. Shreeram S. Humaidi M. Wong E.T. Dhillion M.K. Teo H. Hazra A. Fang C.C. Lopez-Collazo E. Bulavin D.V. Tergaonkar V. WIP1 phosphatase is a negative regulator of NF-kappaB signalling.Nat. Cell Biol. 2009; 11: 659-666Crossref PubMed Scopus (126) Google Scholar, J. Fan G.H. Wadzinski B.E. Sakurai H. Richmond A. Protein phosphatase 2A interacts with and directly dephosphorylates RelA.J. Biol. Chem. 2001; 276: 47828-47833Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar, M. T. M. R. G. F. Y. M. M. and nuclear factor-kappa B signaling in Full Text Full Text PDF PubMed Scopus Google Scholar). We further HDAC5 regulated NF-κB signaling by The the HDAC5 could not the mRNA levels of (Fig. in THP-1 cells with or LPS stimulation. assays indicated that and PP2Ac with HDAC5 (Fig. in previous of the catalytic subunit or PP2Ac significantly the IKKβ HDAC5 the IKKβ phosphorylation only when with but not and (Fig. HDAC5 could the dephosphorylation of IKKβ, p65, and IκBα by PP2Ac (Fig. which was further by NF-κB reporter assays (Fig. When the HDAC5 cells with PP2A inhibitor the phosphorylation of IKKβ and p65 was significantly enhanced (Fig. These results that HDAC5 negatively regulates PP2A, the inhibitor of NF-κB to NF-κB signaling. The or endogenous experiments indicated that the PP2Ac could with IKKβ, or p65, which suggested that these proteins the substrate of PP2Ac (Fig. and the IKKβ, and PP2Ac in the However, HDAC5 did not the between IKKβ and PP2Ac (Fig. the partial enzyme active mutant of HDAC5 or of HDAC5 had on the of IKKβ and PP2Ac (Fig. These results suggested that HDAC5 IKKβ, and p65 phosphorylation by regulating PP2Ac activity. The that the deacetylase activity of HDAC5 was to regulate NF-κB signaling (Fig. indicated that deacetylation of of PP2Ac involved in regulating phosphatase activity. endogenous PP2Ac was in and THP-1 (Fig. and LPS or TNFα acetylation of PP2Ac (Fig. of HDAC5 resulted in of the acetylation of PP2Ac in BMDMs in the of LPS was enhanced in the LPS challenge (Fig. The acetylation of PP2Ac was reduced HDAC5 (Fig. the acetylation of PP2Ac was when with the HDAC5 inhibitor A (Fig. The acetylation of PP2Ac was higher in cells the HDAC5 deacetylase partial inactive mutant in cells the HDAC5 (Fig. the mutant did not the dephosphorylation of IKKβ, p65, and IκBα by PP2Ac (Fig. These results that acetylation of PP2Ac is for its phosphatase and HDAC5 PP2Ac to the phosphorylation and activation of To PP2Ac interacts with we HDAC5 with in (Fig. The results that the of HDAC5 was for the of PP2Ac with HDAC5 (Fig. Collectively, these data suggested that HDAC5 could PP2Ac to the phosphorylation and activation of HDAC5 did not affect the of trimeric of PP2A not We to the acetylation of identified was into to the state of the by and reporter the still partial to the NF-κB reporter (Fig. only the mutant resulted in higher phosphorylation of IKKβ and p65 (Fig. the mutant into a to the state of the reduced the phosphorylation of IKKβ and p65 compared with the and the enzyme activity mutant was as a positive control (Fig. in vitro PP2A phosphatase a PP2A phosphatase enzyme a lower phosphatase activity in or PP2A and HDAC5 compared with the and (Fig. To further the of HDAC5 on regulating the phosphatase activity of PP2A, we an in vitro PP2A phosphatase that PP2Ac but not the could the phosphorylation of IKKβ at or phosphorylation of p65 at The of but not the enhanced the phosphorylation of IKKβ or p65 (Fig. These results indicated that IKKβ and p65 are of PP2A, and the deacetylase activity of HDAC5 could negatively regulate PP2A phosphatase activity. in the acetylation of PP2Ac compared with and other such as These results suggested that the Lys136 is the acetylation of we PP2Ac THP-1 during LPS stimulation. We found that the acetylation of PP2Ac at Lys136 by p65 phosphorylation (Fig. HDAC5 regulated NF-κB activation by the acetylation of which the phosphatase activity. In the is in We that HDAC5 is a novel positive regulator of the NF-κB pathway in vitro and in vivo. HDAC5 IKKβ, p65, and IκBα phosphorylation in response to stimuli, TNF, or We have that HDAC5 deacetylated the PP2Ac directly to its phosphatase activity. the acetylation of PP2Ac at Lys136 is for the phosphatase and deacetylated PP2Ac IKKβ, p65, and IκBα in a active these to the that HDAC5 functions as a positive that regulates NF-κB as in the of such as In our of HDAC5 in macrophages was with significantly levels of proinflammatory TNFα and The that HDAC5 significantly TNFα and IL-6 the of a partial inactivating had a proinflammatory We that the of the HDAC is for the inflammatory regulatory function of IKK activity was a key to the NF-κB activation by IKK activity was by kinases and phosphatases to (9Li H.Y. Liu H. Wang C.H. Zhang J.Y. Man J.H. Gao Y.F. Zhang P.J. Li W.H. Zhao J. Pan X. Zhou T. Gong W.L. Li A.L. Zhang X.M. Deactivation of the kinase IKK by CUEDC2 through recruitment of the phosphatase PP1.Nat. Immunol. 2008; 9: 533-541Crossref PubMed Scopus (116) Google Scholar, H. M. and function of IKK and PubMed Scopus Google Scholar). In response to with or IKK could but higher activity to a activity after stimulation, an role F. H. A. Li J. M. M. A. A. and kinases for NF-kappaB PubMed Scopus Google Scholar). a of was on IKK activation and deactivation the regulation involved in deactivation factors such as to the PP2A active the core enzyme subunit (PP2Ac) is to different posttranslational modifications and to the and of different PP2A Here, we reported that HDAC5 could the core enzyme We identified Lys136 as the key acetylation of which the phosphatase activity of The PP2Ac mutant a compared with PP2Ac or PP2Ac The mechanism for that the state and of PP2Ac by its catalytic activity was also We that the acetylation was enhanced and during or LPS stimulation, with the of IKK It was also that dephosphorylation is an in the of transcription factors after a with PP2Ac and stimulation, p65 was by protein serine/threonine p65 was the to the nucleus to the expression of the transcription factor form a with PP2A and by It that the of dephosphorylation had to active to maintain a state of phosphorylation of p65, which was for the of the transcription the in phosphorylation and activation of the transcription We found that HDAC5 is involved in the regulation of phosphatase activity. The HDAC5 could regulate the NF-κB The a of mRNA after the of LPS L. Stroh T. Erben U. Sittig M. Liebig S. Siegmund B. Glauben R. Histone deacetylase 5 regulates the inflammatory response of macrophages.J. Cell Mol. Med. 2015; 19: 2162-2171Crossref PubMed Scopus (36) Google Scholar). Our results suggested the HDAC5 deacetylase activity could enhanced during TNFα (Fig. suggested that HDAC5 regulates the NF-κB activation and is PP2A regulated the activity of key proteins cell and These proteins and Full Text Full Text PDF PubMed Scopus Google Scholar, S. Zhou M. Protein phosphatase 2A regulates signaling by dephosphorylating and on critical binding Biol. Full Text Full Text PDF PubMed Scopus Google Scholar, P.J. K. H. R. A the protein phosphatase 2A subunit as a inhibitor of PubMed Scopus Google Scholar, Y. Wang J. R. X. of by of and protein phosphatase Commun. 2015; PubMed Scopus Google Scholar, G. S. S. S. M. M. K. H. A. T. F. M. The and PP2A regulate phosphorylation to levels and cell survival 2017; Full Text Full Text PDF PubMed Scopus Google Scholar). HDAC5 could regulate phosphatase activity which suggested that HDAC5 involved in regulating these signaling pathways. The of the in the still further In we have an mechanism for regulating the PP2A We have identified HDAC5 as a key regulator of NF-κB our results that HDAC5 PP2Ac at Lys136 to its phosphatase activity and maintain the phosphorylation of IKKβ, and p65. and human the indicated The in are in in to the for the and of by the of in and the by the at of of mice on the of mice of by of the mice and specific in of cell in a at with The HEK293T THP-1 and cells and cells in with and THP-1 cells in with and virus and virus by with was by virus and as (15Tang J.L. Yang Q. Xu C.H. Zhao H. Liu Y.L. Liu C.Y. Zhou Y. Gai D.W. Pei R.J. Wang Y. Hu X. Zhong B. Wang Y.Y. Chen X.W. Chen J.Z. Histone deacetylase 3 promotes innate antiviral immunity through deacetylation of TBK1.Protein Cell. 2021; 12: 261-278Crossref PubMed Scopus (10) Google Scholar, 17Yang Q. Tang J. Pei R. Gao X. Guo J. Xu C. Wang Y. Wang Q. Wu C. Zhou Y. Hu X. Zhao H. Wang Y. Chen X. Chen J. Host HDAC4 regulates the antiviral response by inhibiting the phosphorylation of IRF3.J. Mol. Cell Biol. 2019; 11: 158-169Crossref PubMed Scopus (14) Google Scholar). with SeV or for the indicated stimulated with LPS or for the indicated to the into the vector and into HEK293T after the and to HEK293T or THP-1 cells in the of The cells with for at 5 HDAC5 and BMDMs the and of and HDAC5-deficient mice and in at for with and was at Mammalian expression for or HDAC5 and its or PP2Ac and its site-directed and by by and a of was in The NF-κB promoter reporter was was The for IKKβ, NF-κB p65, by our The IRF1 promoter reporter was by Mammalian expression for was by transfected into HEK293T cells with the HEK293T in was transfected with NF-κB or reporter and reporter with HDAC5 or empty control the cells stimulated with virus or for and with by the between activity and activity. in cell or mice and IL-6 to the The transfected at a of to the The of specific for HDAC5 and The in HEK293T cells by of the or and and into the vector or the was and to cells, by cell through HDAC5 shRNA and was with the by the The data to the expression of the for The was to expression The for are in and cells with 1 1 and a inhibitor for in 4 Cell at for at 4 and the the and in the and with protein and with specific for with at 4 Protein immune by at for 1 at with and in by to and for 1 with by with the The proteins and substrate and with a to the HEK293T cells on and transfected with the indicated by or stimulated as the indicated with with and with with the indicated and the with with a HEK293T cells transfected with indicated The expressed proteins by the indicated The with cell and with kinase by of as indicated with kinase and at for in by and by with indicated HEK293T cells transfected with indicated The expressed PP2Ac proteins by the indicated The with by with through a assays in of for at The levels in the a to the HEK293T cells transfected with PP2Ac or HDAC5 or and IKKβ or p65 indicated after of four IKKβ, p65, or was The PP2Ac was with HDAC5 or to the deacetylation of the indicated proteins in phosphatase 1 5 at for was by of HEK293T cells stimulated with TNFα for the indicated the endogenous HDAC5 proteins by the specific The with by with HDAC The HDAC activity was a HDAC to the between the in the 5 and and was reported as highly with results are as The during the are the on The that have of with the of We for its during the of for the core of of for We Zhao in for C. X. data C. J. Q. Y. Y. and X. C. C. Y. and J. J. Chen X. C. and J. Chen X. C. C. X. and J. T. Q. Y. and H. J. Chen J. Chen and was by the and of to X. C. and to Y. the for in to J. C.

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