Signal transducer and activator of transcription 3 (STAT3) triggered production of Th-17 cytokines mediates protective immunity against fungi. Mutations affecting the STAT3/interleukin 17 (IL-17) pathway cause selective susceptibility to fungal (Candida) infections, a hallmark of chronic mucocutaneous candidiasis (CMC). In patients with autosomal dominant CMC, we and others previously reported defective Th17 responses and underlying gain-of-function (GOF) STAT1 mutations, but how this affects STAT3 function leading to decreased IL-17 is unclear. We also assessed how GOF-STAT1 mutations affect STAT3 activation, DNA binding, gene expression, cytokine production, and epigenetic modifications. We excluded impaired STAT3 phosphorylation, nuclear translocation, and sequestration of STAT3 into STAT1/STAT3 heterodimers and confirm significantly reduced transcription of STAT3-inducible genes (RORC/IL-17/IL-22/IL-10/c-Fos/SOCS3/c-Myc) as likely underlying mechanism. STAT binding to the high affinity sis-inducible element was intact but binding to an endogenous STAT3 DNA target was impaired. Reduced STAT3-dependent gene transcription was reversed by inhibiting STAT1 activation with fludarabine or enhancing histone, but not STAT1 or STAT3 acetylation with histone deacetylase (HDAC) inhibitors trichostatin A or ITF2357. Silencing HDAC1, HDAC2, and HDAC3 indicated a role for HDAC1 and 2. Reduced STAT3-dependent gene transcription underlies low Th-17 responses in GOF-STAT1 CMC, which can be reversed by inhibiting acetylation, offering novel targets for future therapies.

Cdyl (chromodomain-Y-like) is a chromodomain-containing protein that is predominantly expressed during mouse spermiogenesis. In its carboxy-terminal portion, there is a domain with homology to the coenzyme A (CoA) pocket of the enoyl-CoA hydratase/isomerase, which is shown here to be able to bind CoA and histone deacetylases (HDACs). It also efficiently represses transcription. Moreover, the binding of Hdac1 represses the ability of Cdyl to bind CoA, and a Cdyl-CoA interaction only occurs in the absence of HDACs. These data suggest that Cdyl is primarily a transcriptional co-repressor. However, the degradation of cellular Hdac1 and Hdac2, as observed here in the elongating spermatids, may provide an HDAC-free environment in which Cdyl could bind CoA and participate in the global chromatin remodelling that occurs in these cells.

Histone deacetylase (HDAC) enzymes modulate gene expression through the deacetylation of acetylated lysine residues on histone proteins. They operate in biological systems as part of multiprotein corepressor complexes. To understand the reactivity of isolated HDACs and the contribution of cofactor binding to reactivity, the reaction kinetics of isolated, recombinant human HDACs 1, 2, 3, 6, 8, and 10 were measured using a novel, continuous protease-coupled enzyme assay. Values of k(cat) and k(cat)/K(m) and the pH dependence of these values were determined for the reactions of each isozyme with acetyl-Gly-Ala-(N(epsilon)-acetyl-Lys)-AMC. Values of k(cat) spanned the range of 0.006-2.8 s(-1), and k(cat)/K(m) values ranged from 60 to 110000 M(-1) s(-1). The pH profiles for both k(cat) and k(cat)/K(m) were bell-shaped for all of the HDAC isozymes, with pH optima at approximately pH 8. Values of K(i) for the inhibitor trichostatin A were determined for each isozyme. The inhibition constants were generally similar for all HDAC isozymes, except that the value for HDAC8 was significantly higher than that for the other isozymes. The reaction of HDAC8 with an alternative substrate was performed to assess the steric requirements of the HDAC8 active site, and the effect of phosphorylation on HDAC1 activity was examined. The results are discussed in terms of the biological roles of the HDAC enzymes and the proposed reaction mechanism of acetyllysine hydrolysis by these enzymes.

BACKGROUND

Our recent studies of microRNA (miRNA) expression signature demonstrated that microRNA-874 (miR-874) was significantly downregulated in maxillary sinus squamous cell carcinoma (MSSCC), and a putative tumour-suppressive miRNA in human cancers. Our aim of this study was to investigate the functional significance of miR-874 in cancer cells and to identify novel miR-874-mediated cancer pathways and responsible genes in head and neck squamous cell carcinoma (HNSCC).

METHODS

Gain-of-function studies using mature miR-874 were performed to investigate cell proliferation and cell cycle distribution in HNSCC cell lines (SAS and FaDu). To identify miR-874-mediated molecular pathways and targets, we utilised gene expression analysis and in silico database analysis. Loss-of-function assays were performed to investigate the functional significance of miR-874 target genes.

RESULTS

Expression levels of miR-874 were significantly downregulated in HNSCC tissues (including oral, pharyngeal and laryngeal SCCs) compared with normal counterpart epithelia. Restoration of miR-874 in SAS and FaDu cell lines revealed significant inhibition of cell proliferation and induction of G2/M arrest and cell apoptosis. Our expression data and in silico analysis demonstrated that miR-874 modulated the cell cycle pathway. Moreover, histone deacetylase 1 (HDAC1) was a candidate target of miR-874 regulation. Luciferase reporter assays showed that miR-874 directly regulated HDAC1. Silencing of the HDAC1 gene significantly inhibited cell proliferation and induced G2/M arrest and cell apoptosis in SAS cells.

CONCLUSIONS

Downregulation of miR-874 was a frequent event in HNSCC. miR-874 acted as a tumour suppressor and directly targeted HDAC1. Recognition of tumour-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of HNSCC oncogenesis and suggests novel therapeutic strategies for the disease.

PIASy, a member of the protein inhibitor of activated STAT (PIAS) family, represses the transcriptional activity of the androgen receptor (AR). In this report, we investigate the mechanism of PIASy-mediated repression of AR. We show that AR binds to the RING-finger like domain of PIASy. PIASy contains two transcriptional repression domains, RD1 and RD2. RD1, but not RD2, is required for PIASy-mediated repression of AR. We show that the RD1 domain binds HDAC1 and HDAC2 and that HDAC activity is required for PIASy-mediated AR repression. PIAS proteins possess small ubiquitin-related modifier (SUMO) E3 ligase activity. Conjugation of SUMO-1 to AR has been implicated in the regulation of AR activity. We examine if the SUMO ligase activity of PIASy is required for PIASy to repress AR. We show that a mutant PIASy, defective in promoting sumoylation, retains the ability to repress AR transcription. In addition, mutation of all the known sumoylation acceptor sites of AR does not affect the transrepression activity of PIASy on AR. Our results suggest that PIASy may repress AR by recruiting histone deacetylases, independent of its SUMO ligase activity.

Prenatal alcohol exposure (EtOH) results in insulin resistance in rats of both sexes with increased expression of hepatic gluconeogenic genes and glucose production. To investigate whether hepatic insulin signaling is defective, we studied 3-mo-old female offspring of dams that were given EtOH during pregnancy compared with those from pair-fed and control dams. We performed an intraperitoneal pyruvate tolerance test, determined the phosphorylation status of hepatic phosphoinositide-dependent protein kinase-1 (PDK1), Akt, and PKCzeta before and after intravenous insulin bolus, and measured mRNA and in vivo acetylation of TRB3 (tribbles 3) and PTEN (phosphatase and tensin homolog deleted on chromosome ten) as well as the expression of the histone acetylase (HAT) PCAF (p300/CREB-binding protein-associated factor), histone deacetylase-1 (HDAC1), and HAT and HDAC activities. In EtOH compared with pair-fed and control offspring, basal and pyruvate-induced blood glucose was increased, insulin-induced PDK1, Akt, and PKCzeta phosphorylation was reduced, and expression of PTEN and TRB3 was increased while their acetylation status was decreased in association with increased HDAC and decreased HAT activities. Thus female adult rats prenatally exposed to EtOH have increased gluconeogenesis, reduced insulin signaling, and increased PTEN and TRB3 expression in the liver. In addition, PTEN and TRB3 are hypoacetylated, which can contribute to Akt-inhibiting activity. These results suggest that hepatic insulin resistance in rats prenatally exposed to EtOH is explained, at least in part, by increased PTEN and TRB3 activity due to both increased gene expression and reduced acetylation.

How tumour suppressor p53 bifurcates cell cycle arrest and apoptosis and executes these distinct pathways is not clearly understood. We show that BAX and PUMA promoters harbour an identical MAR element and are transcriptional targets of SMAR1. On mild DNA damage, SMAR1 selectively represses BAX and PUMA through binding to the MAR independently of inducing p53 deacetylation through HDAC1. This generates an anti-apoptotic response leading to cell cycle arrest. Importantly, knockdown of SMAR1 induces apoptosis, which is abrogated in the absence of p53. Conversely, apoptotic DNA damage results in increased size and number of promyelocytic leukaemia (PML) nuclear bodies with consequent sequestration of SMAR1. This facilitates p53 acetylation and restricts SMAR1 binding to BAX and PUMA MAR leading to apoptosis. Thus, our study establishes MAR as a damage responsive cis element and SMAR1-PML crosstalk as a switch that modulates the decision between cell cycle arrest and apoptosis in response to DNA damage.

The tumor suppressor retinoblastoma protein family members pRb, p107, and pRb2/p130 are potent negative transcriptional regulators. The best understood target is the transcription factor E2F, which activates cell cycle-dependent transcription of genes controlling and promoting the cell division cycle (e.g., cyclin A). pRb2/p130 is known to be important in implementing cell cycle exit into G0 due to serum deprivation or various differentiation programs. Several recent studies demonstrated the effect histone acetylases and histone deacetylases (HDACs) have on fine-tuning transcriptional regulation of eucaryotic cells. In this study, we demonstrate that pRb2/p130 binds to HDAC1. This interaction increases the ability of pRb2/p130 to inhibit transcription of the E2F-dependent cyclin A promoter in vivo. We also identify the COOH-terminal 35aa as being necessary for stable interaction between HDAC1 and pRb2/p130.

Liver, pancreas and lung originate from the presumptive foregut in temporal and spatial proximity. This requires precisely orchestrated transcriptional activation and repression of organ-specific gene expression within the same cell. Here, we show distinct roles for the chromatin remodelling factor and transcriptional repressor Histone deacetylase 1 (Hdac1) in endodermal organogenesis in zebrafish. Loss of Hdac1 causes defects in timely liver specification and in subsequent differentiation. Mosaic analyses reveal a cell-autonomous requirement for hdac1 within the hepatic endoderm. Our studies further reveal specific functions for Hdac1 in pancreas development. Loss of hdac1 causes the formation of ectopic endocrine clusters anteriorly to the main islet, as well as defects in exocrine pancreas specification and differentiation. In addition, we observe defects in extrahepatopancreatic duct formation and morphogenesis. Finally, loss of hdac1 results in an expansion of the foregut endoderm in the domain from which the liver and pancreas originate. Our genetic studies demonstrate that Hdac1 is crucial for regulating distinct steps in endodermal organogenesis. This suggests a model in which Hdac1 may directly or indirectly restrict foregut fates while promoting hepatic and exocrine pancreatic specification and differentiation, as well as pancreatic endocrine islet morphogenesis. These findings establish zebrafish as a tractable system to investigate chromatin remodelling factor functions in controlling gene expression programmes in vertebrate endodermal organogenesis.

A variety of stress stimuli, including ischemia-reperfusion (I/R) injury, induce the transcriptional repressor ATF3 in the kidney. The functional consequences of this upregulation in ATF3 after renal I/R injury are not well understood. Here, we found that ATF3-deficient mice had higher renal I/R-induced mortality, kidney dysfunction, inflammation (number of infiltrating neutrophils, myeloperoxidase activity, and induction of IL-6 and P-selectin), and apoptosis compared with wild-type mice. Furthermore, gene transfer of ATF3 to the kidney rescued the renal I/R-induced injuries in the ATF3-deficient mice. Molecular and biochemical analysis revealed that ATF3 interacted directly with histone deacetylase 1 (HDAC1) and recruited HDAC1 into the ATF/NF-kappaB sites in the IL-6 and IL-12b gene promoters. The ATF3-associated HDAC1 deacetylated histones, which resulted in the condensation of chromatin structure, interference of NF-kappaB binding, and inhibition of inflammatory gene transcription after I/R injury. Taken together, these data demonstrate epigenetic regulation mediated by the stress-inducible gene ATF3 after renal I/R injury and suggest potential targeted approaches for acute kidney injury.

In addition to repressing ERBB2 promoter function, histone deacetylase (HDAC) inhibitors induce the accelerated decay of mature ERBB2 transcripts; the mechanism mediating this transcript destabilization is unknown but depends on the 3' untranslated region (UTR) of ERBB2 mRNA. Using ERBB2-overexpressing human breast cancer cells (SKBR3), the mRNA stability factor HuR was shown to support ERBB2 transcript integrity, bind and endogenously associate with a conserved U-rich element within the ERBB2 transcript 3' UTR, coimmunoprecipitate with RNA-associated HDAC activity, and colocalize with HDAC6. HDAC6 also coimmunoprecipitates with HuR in an RNA-dependent manner and within 6 hours of exposure to a pan-HDAC inhibitor dose, that does not significantly alter cytosolic HuR levels or HuR binding to ERBB2 mRNA. Cellular ERBB2 transcript levels decline while remaining physically associated with HDAC6. Knockdown of HDAC6 protein by small interfering RNA partially suppressed the ERBB2 transcript decay induced by either pan-HDAC or HDAC6-selective enzymatic inhibitors. Three novel hydroxamates, ST71, ST17, and ST80 were synthesized and shown to inhibit HDAC6 with 14-fold to 31-fold greater selectivity over their binding and inhibition of HDAC1. Unlike more potent pan-HDAC inhibitors, these HDAC6-selective inhibitors produced dose-dependent growth arrest of ERBB2-overexpressing breast cancer cells by accelerating the decay of mature ERBB2 mRNA without repressing ERBB2 promoter function. In sum, these findings point to the therapeutic potential of HuR and HDAC6-selective inhibitors, contrasting ERBB2 stability effects induced by HDAC6 enzymatic inhibition and HDAC6 protein knockdown, and show that ERBB2 transcript stability mechanisms include exploitable targets for the development of novel anticancer therapies.

OBJECTIVE

HDAC inhibitors (HDI) are anti-neoplastic drugs with preliminary successful clinical applications in Hodgkin's lymphoma (HL). Systematic investigations of HDAC expression in HL, based on histology and immunohistochemistry are yet rare.

METHODS

We investigated the expression of HDAC1, 2 and 3 in 283 HL on tissue microarrays.

METHODS

Expression of HDAC isoforms was scored in Hodgkin and Reed-Sternberg cells (HRSC) and background infiltrate and compared with freedom of treatment failure (FTF) in 118 cases, for which all data was available.

RESULTS

All analyzable HL expressed the HDAC isoforms 2 (n = 194) and 3 (n = 207) in over 50%, mostly 100%, of HRSC and almost all background lymphocytes. HDAC1 was expressed in 169 of 179 analyzable HL in a mean of 82% and in 172 out of 179 analyzable cases in a mean of 83% of infiltrating lymphocytes. HDAC1 of below 75% in HRSC correlated with worse FTF with 16 out of 32 events, compared with 16 out of 82 in cases with over 75% HDAC1-expressing HRSC.

CONCLUSIONS

HDAC isoforms 1, 2 and 3 are highly expressed in HL. In addition, decreased HDAC1 expression is accompanied by worse outcome in HL.

The mammalian DNA (cytosine-5) methyltransferase (Dnmt1) is involved in the maintenance of methylation patterns in the genome during DNA replication and development. The retinoblastoma gene product, Rb, is a cell cycle regulator protein that represses transcription by recruiting histone deacetylase (HDAC1). In vivo, histone deacetylase associates with Dnmt1. Here we show that Rb itself associates with human Dnmt1 (hDnmt1) independently of its own phosphorylation status. Methyltransferase activity was co-purified with Rb. The regulatory domain of hDnmt1 binds strongly to the B and C pockets of Rb (amino acids 701-872) and inhibits methyltransferase activity by disruption of the hDnmt1-DNA binary complex. Weak interaction of Rb pockets A and B with Dnmt1 was also observed. Overexpression of Rb leads to hypomethylation of the cellular DNA, suggesting that Rb may modulate Dnmt1 activity during DNA replication in the cell cycle.

Fanconi anemia (FA) is an autosomal recessive cancer susceptibility syndrome. The phenotype includes developmental defects, bone marrow failure, and cell cycle abnormalities. At least eight complementation groups (A-H) exist, and although three of the corresponding complementation group genes have been cloned, they lack recognizable motifs, and their functions are unknown. We have isolated a binding partner for the Fanconi anemia group C protein (FANCC) by yeast two-hybrid screening. We show that the novel gene, FAZF, encodes a 486 amino acid protein containing a conserved amino terminal BTB/POZ protein interaction domain and three C-terminal Krüppel-like zinc fingers. FAZF is homologous to the promyelocytic leukemia zinc finger (PLZF) protein, which has been shown to act as a transcriptional repressor by recruitment of nuclear corepressors (N-CoR, Sin3, and HDAC1 complex). Consistent with a role in FA, BTB/POZ-containing proteins have been implicated in oncogenesis, limb morphogenesis, hematopoiesis, and proliferation. We show that FAZF is a transcriptional repressor that is able to bind to the same DNA target sequences as PLZF. Our data suggest that the FAZF/FANCC interaction maps to a region of FANCC deleted in FA patients with a severe disease phenotype. We also show that FAZF and wild-type FANCC can colocalize in nuclear foci, whereas a patient-derived mutant FANCC that is compromised for nuclear localization cannot. These results suggest that the function of FANCC may be linked to a transcriptional repression pathway involved in chromatin remodeling.

Vitamin D(3) upregulated protein 1 (VDUP1) is a candidate tumor suppressor, the expression of which is dramatically reduced in various tumor tissues. In this study, we found that VDUP1 expression is suppressed during human hepatic carcinogenesis, and mice lacking VDUP1 are much more susceptible to diethylnitrosamine-induced hepatocarcinogenesis compared with wild type mice. VDUP1-deficient tumors proliferated significantly more than wild type tumors and had corresponding changes in the expression of key cell cycle regulatory proteins. In addition, the hepatomitogen-induced response was associated with a considerable increase in the release of TNF-α and subsequent enhancement of NF-κB activation in VDUP1-deficient mice. When cells were treated with TNF-α, the VDUP1 level was markedly reduced, concomitant with elevated NF-κB activation. Furthermore, the overexpression of VDUP1 resulted in the robust suppression of TNF-α-activated NF-κB activity via association with HDAC1 and HDAC3. These results indicate that VDUP1 negatively regulates hepatocarcinogenesis by suppressing TNF-α-induced NF-κB activation.

We identified three heterozygous nonsynonymous single nucleotide polymorphisms in the small heterodimer partner (SHP, NROB2) gene in normal subjects and CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy)-like patients, including two novel missense mutations (p.R38H, p.K170N) and one of the previously reported polymorphism (p.G171A). Four novel heterozygous mutations were also identified in the intron ((Intron)1265T->>A), 3'-untranslated region ((3'-UTR)101C->>G, (3'-UTR)186T->>C), and promoter ((Pro)-423C->>T) of the SHP gene. The exonic R38H and K170N mutants exhibited impaired nuclear translocation. K170N made SHP more susceptible to ubiquitination mediated degradation and blocked SHP acetylation, which displayed lost repressive activity on its interacting partners ERRgamma and HNF4alpha but not LRH-1. In contrast, G171A increased SHP mRNA and protein expression and maintained normal function. In general, the interaction of SHP mutants with LRH-1 and EID1 was enhanced. K170N also markedly impaired the recruitment of SHP, HNF4alpha, HDAC1, and HDAC3 to the apoCIII promoter. Molecular dynamics simulations of SHP showed that G171A stabilized the nuclear receptor boxes, whereas K170N promoted the conformational destabilization of all the structural elements of the receptor. This study suggests that genetic variations in SHP are common among human subjects and the Lys-170 residue plays a key role in controlling SHP ubiquitination and acetylation associated with SHP protein stability and repressive function.

Histone deacetylase (HDAC) plays an important role in chromatin remodeling in response to a variety of neurochemical signalings and behavioral manipulations, and may be a therapeutic target for modulation of psychostimulant behavioral sensitization. In this study, we investigated the molecular interaction between histone deacetylase inhibitor (HDACi) and psychostimulant in vivo of mice after repeated treatment with the HDACi, butyric acid (BA) and valproic acid (VPA), alone or in combination with amphetamine. Repeated treatment with amphetamine produced HDACi-like effects: enhanced global histone H4 acetylation level by Western blot as well as specific histone H4 acetylation associated with fosB promoter by chromatin immunoprecipitation in the striatum. Conversely, repeated treatment with BA or VPA produced amphetamine-like effects: enhanced cAMP responsive element binding protein (CREB) phosphorylation at Ser(133) position and increased DeltaFosB protein levels in the striatum. Furthermore, co-administration of BA or VPA with amphetamine produced additive effects on histone H4 acetylation as well as CREB phosphorylation in the striatum. The interplay of HDAC and CREB was also supported by co-immunoprecipitation assays demonstrating that repeated treatment with VPA reduced the association of CREB and HDAC1 in the striatum. Finally, the additive effect of VPA/BA and amphetamine on histone H4 acetylation, phosphorylated CREB, and DeltaFosB was associated with potentiated amphetamine-induced locomotor activity. Thus, HDACi may interact additively with psychostimulants at both histone acetylation and CREB phosphorylation through the CREB:HDAC protein complex in the striatum to modulate DeltaFosB protein levels and psychomotor behavioral sensitization.

Histone deacetetylases (HDACs) are a group of corepressors of transcriptional activators and their levels of expression are potentially dysregulated in prostate cancer. Certain inhibitors of histone deacetylases show anti-tumor activity in prostate cancer cell lines. Here, we systemically studied the expression of HDACs in human prostate cancer and the suppression of prostate cancer growth and invasion by HDAC inhibitor SAHA. HDAC1-5 showed increased expression using a combination of DNA microarray, in-situ hybridization, and immunohistochemistry in benign and malignant human prostate tissue as well as RT-PCR and Western blot analysis on various PCa cell lines. Importantly, HDAC inhibitor SAHA suppressed, in particular, prostate cancer cell growth and invasion determined using cell proliferation and Matrigel invasion assays. The findings of this study show that the expression of HDACs and their associated corepressors are increased in prostate cancer in humans and HDAC inhibitor SAHA could serve as a potential therapeutic agent in prostate cancer in addition to anti-androgens.

While cytotoxic chemotherapy remains the hallmark of cancer treatment, intensive regimens fall short in many malignancies, including high-risk neuroblastoma. One alternative strategy is to therapeutically promote tumor differentiation. We created a gene expression signature to measure neuroblast maturation, adapted it to a high-throughput platform, and screened a diversity oriented synthesis-generated small-molecule library for differentiation inducers. We identified BRD8430, containing a nine-membered lactam, an ortho-amino anilide functionality, and three chiral centers, as a selective class I histone deacetylase (HDAC) inhibitor (HDAC1>> 2>> 3). Further investigation demonstrated that selective HDAC1/HDAC2 inhibition using compounds or RNA interference induced differentiation and decreased viability in neuroblastoma cell lines. Combined treatment with 13-cis retinoic acid augmented these effects and enhanced activation of retinoic acid signaling. Therefore, by applying a chemical genomic screening approach, we identified selective HDAC1/HDAC2 inhibition as a strategy to induce neuroblastoma differentiation.

Altered transforming growth factor-β (TGF-β) signalling has been implicated in tumour development and progression. However, the molecular mechanism behind this alteration is poorly understood. Here we show that profilin-2 (Pfn2) increases Smad2 and Smad3 expression via an epigenetic mechanism, and that profilin-2 and Smad expression correlate with an unfavourable prognosis of lung cancer patients. Profilin-2 overexpression promotes, whereas profilin-2 knockdown drastically reduces, lung cancer growth and metastasis. We show that profilin-2 suppresses the recruitment of HDAC1 to Smad2 and Smad3 promoters by preventing nuclear translocation of HDAC1 through protein-protein interaction at the C terminus of both proteins, leading to the transcriptional activation of Smad2 and Smad3. Increased Smad2 and Smad3 expression enhances TGF-β1-induced EMT and production of the angiogenic factors VEGF and CTGF. These findings reveal a new regulatory mechanism of TGF-β1/Smad signalling, and suggest a potential molecular target for the development of anticancer drugs.

UNASSIGNED

Inflammatory bowel disease (IBD)-associated dysbiosis is characterized by a loss of Faecalibacterium prausnitzii, whose supernatant exerts an anti-inflammatory effect. However, the anti-inflammatory substances in F. prausnitzii supernatant and the mechanism in ameliorating colitis in IBD have not yet been fully investigated.

UNASSIGNED

Experimental colitis models were induced and evaluated by clinical examination and histopathology. Levels of cytokines and ratio of T cells were detected by enzyme-linked immunosorbent assay and flow cytometry analysis, respectively. F. prausnitzii supernatant was separated by macroporous resins. After extraction, the substances in supernatant were identified by gas chromatography-mass spectrometer. T-cell differentiation assay was conducted in vitro. Changes in signaling pathways were examined by immunoblot, immunohistochemistry, and immunofluorescent staining.

UNASSIGNED

We found that the supernatant of F. prausnitzii could regulate T helper 17 cell (Th17)/regulatory T cell (Treg) differentiation. Then, we identified butyrate produced by F. prausnitzii that played the anti-inflammatory effects by inhibiting interleukin (IL)-6/signal transducer and the activator of transcription 3 (STAT3)/IL-17 pathway and promoting forkhead box protein P3 (Foxp3). Finally, we demonstrated that the target of butyrate was histone deacetylase 1 (HDAC1).

UNASSIGNED

It is butyrate, instead of other substances produced by F. prausnitzii, that maintains Th17/Treg balance and exerts significant anti-inflammatory effects in colorectal colitis rodents, by inhibiting HDAC1 to promote Foxp3 and block the IL-6/STAT3/IL-17 downstream pathway. F. prausnitzii could be an option for further investigation for IBD treatment. Targeting the butyrate-HDAC1-T-cell axis offers an effective novel approach in the treatment of inflammatory disease.

DNA topoisomerase II (topo II) is a ubiquitous nuclear enzyme that is involved in DNA replication, transcription, chromosome segregation, and apoptosis. Here we show by immunoprecipitation, pull down with glutathione S-transferase fusion proteins, and yeast two-hybrid analysis that both topo IIalpha and -beta physically interact with the histone deacetylase HDAC1. The in vitro DNA decatenation activity of recombinant topo IIalpha and -beta is inhibited by association with catalytically inactive, recombinant HDAC1. We provide evidence for the in vivo significance of the topo II-HDAC1 association, showing that inhibition of HDAC activity with trichostatin A suppresses apoptosis induced by the topo II poison etoposide, but not by the topoisomerase I inhibitor camptothecin. We suggest that chromatin remodeling by an HDAC-containing complex facilitates both topo II-catalyzed DNA rearrangement and etoposide-induced DNA damage in vivo.

Increased levels of fetal hemoglobin (HbF) can ameliorate the severity of the β-hemoglobin disorders, sickle cell disease (SCD) and β-thalassemia, which are major sources of morbidity and mortality worldwide. As a result, there has been a longstanding interest in developing therapeutic approaches for inducing HbF. For more than 3 decades, the majority of HbF inducers developed were based on empiric observations and have had limited success. Recently, human genetic approaches have provided insight into previously unappreciated regulators of the fetal-to-adult hemoglobin switch and HbF silencing, revealing molecular targets to induce HbF. This article reviews these developments and discusses how molecules including BCL11A, KLF1, MYB, SOX6, miRNAs 15a and 16-1, and histone deacetylase 1 and 2 (HDAC1/2) could be important targets for HbF induction in humans. The current understanding of how these molecules function and the benefits and drawbacks of each of these potential therapeutic targets are also examined. The identification of these regulators of HbF expression is extremely promising and suggests that rationally designed approaches targeting the very mechanisms mediating this switching process could lead to better, less toxic, and more effective strategies for HbF induction.

Methyl-CpG-binding protein 2 (MeCP2) contains a transcriptional repression domain (TRD), which can act by recruitment of a large transcriptional co-repressor complex containing histone deacetylases HDAC1 and 2. We demonstrate here that transient transcription from the SV40 enhancer/promoter or the SV40 promoter is strongly repressed in a histone deacetylase-independent manner, since repression is not alleviated by Trichostatin A (TSA). In a mutational analysis, repression depends on a conserved 30 residue sequence containing two clusters of basic amino acids. Mutation of the first of these clusters inhibits in vitro interaction between TRD and mSin3A. Furthermore, a subdomain of the TRD containing the conserved 30-residue sequence and 16 flanking amino acids was sufficient to compromise VP16-activated transcription. In summary, our results indicate an alternative, histone deacetylase-independent pathway of transcriptional repression by MeCP2.